CROSS-REFERENCE TO RELATED APPLICATIONS

[001] Pursuant to 35 U. S. C. § 1 19 (e), this application claims priority to the filing date of U.S. Provisional Patent Application Serial No. 61/122,723 filed on December 15, 2008; U.S. Provisional Patent Application Serial No. 61/160,289 filed on March 13, 2009; U.S. Provisional Patent Application Serial No.: 61/240,571 filed on September 8, 2009; and U.S. Provisional Patent Application Serial No.: 61/251 ,088 filed on October 13, 2009, the disclosures of which applications are herein incorporated by reference. This application is also a continuation- in-part of U.S. Patent Application Serial No. 1 1/912,475 filed on April 28, 2006 and a continuation-in-part of U.S. Patent Application Serial No. 12/324,798 filed on November 26, 2008, the disclosures of which applications are herein incorporated by reference.

FIELD OF THE INVENTION

[002] The present invention relates to receivers in a communication system and, more specifically, to receivers that detect data transmission encoded in current flow through a conducting solution with the ability to manage power and control dosage.

INTRODUCTION

[003] There are many instances in both medical and non-medical applications where one desires to note a personal event, i.e., an event that is specific to a given individual. Examples of medical applications where one may wish to note an event that is specific to a given individual include, but are not limited to, the onset of one or more physiological parameters of interest, including disease symptoms, the administration of a medication, etc. Examples of non-medical applications where one desires to note an event that is specific to a given individual include, but are not limited to: the ingestion of certain types of foods (e.g., for individuals on controlled diets), the commencement of an exercise regimen, etc.

[004] Because there are many instances where one wishes to note a personal event, a variety of different methods and technologies have been developed to make such notation possible. For example, log books and techniques have been developed in which individuals, e.g., patients and/or their health care provides, can record, e.g., by manually writing or data entry, time and date of an event. However, there continues to be a need for improvements in personal event monitoring. For example, manually logging when an event takes place can be time consuming and prone to error.

SUMMARY

[005] Receivers, which may be external, implantable, semi-implantable, etc., are provided. Aspects of receivers of the invention include the presence of one or more of: a high power-low power module; an intermediary module; a power supply module configured to activate and deactivate one or more power supplies to a high power processing block; a serial peripheral interface bus connecting master and slave blocks; and a multi-purpose connector. Receivers of the invention may be configured to receive a conductively transmitted signal. Also provided are systems that include the receivers, as well as methods of using the same.

BRIEF DESCRIPTION OF THE FIGURES

[006] FIG. 1 is a representation of a receiver for detection of data transmission through a living subject. [007] FIG. 1 A is a block diagram representation of the receiver of FIG. 1 in accordance with the teachings of the present invention. [008] FIG. 1 B is a block diagram representation of a power management module of the receiver of FIG. 1 A in accordance with the teaching of the present invention. [009] FIG. 2 is a functional block diagram of a demodulation circuit that performs coherent demodulation that may be present in a receiver, according to one aspect [010] FIG. 3A illustrates a beacon switching module providing a sniff period longer than a transmit signal repetition period. [011] FIG. 3B illustrates a beacon switching module providing a short but frequent sniff period and a long transmit packet are provided. [012] FIG. 3C illustrates a flow chart for a sniff procedure performed by a sniff module, according to an aspect. [013] FIG. 3D illustrates a functional block diagram for a beacon module within a receiver, according to one aspect. [014] FIG. 4 illustrates a beacon functionality wherein a beacon is associated with one frequency and a message is associated with another frequency. [015] FIG 5 illustrates a functional block diagram of an ECG sensing module that may be present in a receiver, according to one aspect. [016] FIG. 6 illustrates a functional block diagram of an accelerometer module that may be present in a receiver of the invention, according to one aspect. [017] FIG. 7 is a block diagram of the different functional modules that may be present in a receiver, according to one aspect. [018] FIG. 8 is a block diagram of a receiver, according to one aspect. [019] FIG. 9 provides a block diagram of a high frequency signal chain in a receiver, according to one aspect. [020] FIG. 10 is a three-dimensional view of an external signal receiver, according to one aspect. [021] FIG. 1 1 provides an exploded view of the signal receiver shown in

FIG. 10, according to one aspect. [022] FIG. 12 provides an exploded view of the adhesive patch component of the signal receiver shown in FIGS. 10 and 1 1 , according to one aspect. [023] FIGS 13A to 13E provide various views of a two-electrode external signal receiver, according to one aspect. [024] FIGS. 14A to 14D provide block diagrams of hardware configurations that may be present in a signal receiver as shown in FIGS.

13A to 13E, according to one aspect. [025] FIG. 15A provides a diagram of how a system that includes a signal receiver and an ingestible event marker may be employed, according to one aspect. [026] FIG. 15B provides a pharmaceutical delivery system that receives control information form a receiver and control the dosage delivery. [027] FIG. 16 provides a block diagram showing a receiver connected to a patient. [028] FIG. 17 provides a block diagram showing a receiver connected to an external power charger. [029] FIG. 18 provides a block diagram showing a receiver connected to an external control and data communication device. [030] FIGS. 19A-19B show a diagram of a router according to an aspect of the invention that discriminates a signal based on voltage level. [031 ] FIGS. 20A-20C show a diagram of a router according to an aspect of the invention that discriminates a signal based on frequency. [032] FIG. 21 shows a diagram of a router according to an aspect of the invention that discriminates a signal by employing active switches. [033] FIGS. 22A-C (referred to collectively as FIG. 22) provide a circuit schematic for multi-purpose electrode connections in accordance with an aspect of the invention. [034] FIGS. 23A-B (referred to collectively as FIG. 23) provide a circuit schematic for an internal power source block of an external receiver in accordance with an aspect of the invention. [035] FIGS. 24A-C(referred to collectively as FIG. 24) provide a circuit schematic for an internal power source block of an external receiver in accordance with an aspect of the invention [036] FIG. 25 provides a schematic of component / functionality relationships. [037] FIGS. 26A-B (referred to collectively as FIG. 26) provide a circuit diagram of circuitry for controlling the power supply to various components of a receiver that includes a multi-purpose connector, according to one aspect. [038] FIG. 27 provides a circuit diagram modeling the drive scheme in an electrode impedance measurement module, according to one aspect. [039] FIG. 28 provides a circuit diagram for an electrode impedance measurement module using a 3-wire ohmmeter, according to one aspect of the invention. [040] FIG. 29 shows state flow diagram for the power management module and operation of the receiver. [041 ] FIG. 30 provides a block diagram of a hardware accelerator module, according to one aspect.

DETAILED DESCRIPTION

[042] Receivers, which may be external or implantable, are provided. Aspects of receivers of the invention include the presence of one or more of: a high power-low power module; an intermediary module; a power supply module configured to activate and deactivate one or more power supplies to a high power processing block; a serial peripheral interface bus connecting master and slave blocks; and a multi-purpose connector. Receivers of the invention may be configured to receive a conductively transmitted signal. Also provided are systems that include the receivers, as well as methods of using the same.

[043] Receivers of the present invention are electrical devices that include circuitry and logic present in a housing, where the devices are configured to perform one or more medical functions. The term "medical" is used broadly to refer to any type of function that is performed in regard to the health of a living subject, such as a patient. As such, a device is considered to be medical device if it functions to receive data with respect to one or more parameters of a subject, whether the subject is in a healthy or in a disease state. Parameters of interest include those described in greater detail below, such as physiologic parameters, signals from other medical devices, such as ingestible event marker (IEM) devices, etc. As such, medical devices of interest are those that may be used in therapeutic applications or non-therapeutic applications, e.g., as described in greater detail below. 4] In certain embodiments of the present invention, the receivers are devices that are sized to be stably associated with a living subject, e.g., patient, in a manner that does not substantially impact movement of the living subject and yet provides an intended function, such as signal receiving functionality, for extended periods of time. The term "patient" as used herein refers broadly to subjects suspected of or known to be suffering from a disease or abnormality, as well as subjects who are healthy. Receivers in accordance with the teaching of the invention may be associated with a patient's body by any convenient means, such as attaching the device to a patient's body or clothing, e.g., with tape, or by use of a clip, loop, or belt. Alternatively, the device may be placed in a compartment of clothing worn by the patient, such as the patient's pocket. Where desired, the device may be configured to be continuously associated with the patient for an extended period of time, e.g., minutes to months. In one example, the device may be configured to be continually associated with the patient for one week or more. In some instances, the devices are configured by associated directly with a topical skin site of a subject. In yet other aspects, the devices are configured to be implantable. As the devices are sized to be stably associated with a living subject in a manner that does not substantially impact movement of the living subject, aspects of the devices have dimensions that, when employed with a subject, such as a human subject, will not cause the subject to experience any difference in its ability to move. As such, in these aspects, the device is dimensioned such that its size and shape do not hinder the ability of the subject to physically move. Devices of the invention may have a size that provides for functionality when applied to a topical body location, for example as described above. In such instances, the devices may have a total volume of 50 cm ³ or less, such as 30 cm ³ or less, including 25 cm ³ or less, such as 20 cm ³ or less. In certain aspects, the device has a small size, where in certain aspects, the device occupies a volume of space of about 5 cm ³ or less, such as about 3 cm ³ or less, including about 1 cm ³ or less. Devices of the invention may have a longest dimension that is 30 cm or less, such as 20 cm or less, including 1 5 cm or less.

[045] Despite the small size of the receivers, the devices can operate for extended time periods. As such, the receivers may operate for periods of one week or longer, such as two weeks or longer, including one month or longer, three months or longer, six months or longer, including twelve months or longer. To provide for this operation over extended time periods and in view of the small size of the receivers, the devices are configured for low power consumption. By low power consumption is meant that the average power consumption of the device for a 24 hour period is mA or less, such as 100 μA or less, and including 10 μA or less. The average current draw of the receiver when present in an idle mode (described in greater detail below) is 100 μA or less, such as 10 μA or less and including μA or less. The average current draw of the receiver when present in a storage mode (described in greater detail below) is 10μA or less, such as 1 μA or less and including 0.1 μA or less. In some instances, the current draw of the receiver when present in an active state (as described in greater detail below) ranges from 3μA to 30 mA, such as from 30μA to 3 mA, and including from 30μA to 300μA.

[046] In certain aspects, the receivers of the invention are signal receivers. Signal receivers are devices that are configured to receive a signal from another device, such as a trans-body conductively transmitted signal (reviewed in greater detail below). Where the receivers are signal receivers, the receivers may be configured to receive an ingestible event marker emitted signal, as described in greater detail below.

[047] Receivers of the invention may include a variety of different modules which are configured, e.g., via hardware and/or software implementation, to perform one or more functions of the device. Modules are made up of one or more functional blocks which act in concert to perform a particular function, which is the purpose of the module. A given module may be implemented as hardware, software or a combination thereof. Modules that may be present in receivers of the invention are now reviewed in greater detail below.

[048] Aspects of the devices include a high power-low power module. High power-low power modules are modules that include high power functional block and a low power functional block. By low power functional block is meant a functional block that performs processing and requires low current draw and power consumption. The low power functional block performs at least one discrete function — e.g., a function requiring non-high performance processing, where examples of such functions include maintaining an idle state, monitoring a bus, awaiting an occurrence of a signal, such as an interrupt signal, etc. Of interest as low power functional blocks are functional blocks that draw a current of 10 μA or less and including 1 μA or less. By high power functional block is meant a functional block that performs higher performance processing requiring larger current draw and power consumption than the low power functional block. The high power functional block performs at least one discrete function, such as processing conductively transmitted signals, processing received physiological data, etc. The larger computational processing may involve, for example, executing digital signal processing algorithms (such as, Finite Impulse Response (FIR) filters, Fast Fourier transforms (FFTs), etc.). Examples of high power functional blocks are functional blocks that draw a current of 30 μA or more, such as 50μA or more in order to perform their designated functions.

[049] The low and high power functional blocks may be implemented in a variety of different ways. For example, the low and high power functional blocks may be implemented on separate processors or may be implemented as separate circuit elements of a system on chip (SOC) structure, among other configurations. Further details regarding hardware implementations of interest are provided below. Receivers of interest include at least one low power functional block and at least one high power functional block. In some instances, the receivers will include additional low and/or high power functional blocks, as desired to implement a particular receiver.

[050] Receivers of the invention may also include an intermediary module which is configured to cycle the high power functional block between active and inactive states. By active state is meant a state in which the functional block is performing its designated function or functions, such as demodulating and/or processing a received signal, processing physiological data, etc. By inactive state is meant a state in which the functional block is not performing its designated function or functions, where the inactive state may be an idle or sleep state, e.g., where the functional block draws minimal current (such as 1 μA or less, including 0.1 μA or less) or an off state, where the functional block draws no current. By "cycle" is meant that the intermediary module transitions the high power functional block between active and inactive states. In other words, the intermediary module changes the state of the functional block from active to inactive, or vice versa. The intermediary module may cycle the high power functional block between an active and inactive state according to different inputs, such as a predetermined schedule (for example as providing by programming of the receiver) or an applied stimulus. In some instances, the intermediary module may cycle the high power functional block between active and inactive states according to a predetermined schedule. For example, the intermediary module may cycle the high power functional block between active and inactive states every 20 sec, such as every 10 sec, and including every 5 sec. In some instances, the intermediary module may cycle the high power functional block between active and inactive states according to an applied stimulus, such as receipt of a conductively transmitted signal, in response to one or more predetermined physiological parameters, in response to user instructions (for example as implemented by depressing an operational button on the receiver or sending a command signal to the receiver) etc.

[051 ] The receiver may be configured to have various states — e.g., an idle state or one or more active states. Accordingly, the intermediary module may cycle the high power functional block between an active and inactive state as needed, depending on the desired function at a given time of the device. In the active state, the receiver is performing one or more active functions, such as receiving a signal, processing a signal, transmitting a signal, obtaining physiological data, processing physiological data, etc. In an idle state, the receiver draws minimal current, for example as described above. In the idle state, the receiver may perform minimal functions in order to minimize current draw, such as maintain configurations, maintain sleep modes, etc. However, in the idle state the receiver does not perform functions that require more than the minimal current draw. The intermediary module may cycle the receiver between active and idle states according to different inputs, such as a predetermined schedule (for example as provided by receiver programming) or applied stimulus, such as described above.

[052] Receivers of interest may be configured to perform a transbody conductive signal (such as an IEM or smart parenteral device signal) detection protocol. Such devices may be viewed as signal receivers. Transbody conductive signal detection protocols are processes in which the signal receiver is in a state in which it can receive a signal emitted by an IEM or smart parenteral device, and process the signal as desired, e.g., by performing one or more tasks, such as decoding the signal, storing the signal, time-stamping the signal, and retransmitting the signal, as described in greater detail below.

[053] Receivers of interest, such as signal receivers, may also be configured to perform a physiological data detection protocol when present in an active state, e.g., to obtain ECG data, accelerometer data, temperature data, etc., as described in greater detail below.

[054] Referring now to FIGS. 1 , 1A, and 1 B illustrate one embodiment of a receiver of the present invention. The receiver 100 is shown in position on a living subject 102. The receiver 100 is shown attached to a left midsection of the subject 102. However, the scope of the present invention is not limited by the location of the receiver 100 on the subject 102.

[055] Referring now to FIG. 1A, the receiver 100 includes a power unit or power source 200, an operation unit 202 that includes an electrode 202A, an operation or processing unit 204, and a memory unit 206. The receiver 100 also includes a power management module 208 that controls the power consumption. The receiver 100 is capable of communicating with other near-by devices using a transmission module 210. Furthermore, the receiver 100 may include various features such as an accelerometer for detection of the orientation of the receiver 100. In instances where the subject is laying down or in a horizontal position, the receiver 100 is capable of detecting that position and the duration of time that the subject remains in that position.

[056] Additionally, the receiver 100 may further include one or more distinct physiological parameter sensing abilities. By physiological parameter sensing ability is meant a capability of sensing a physiological parameter or biomarker, such as, but not limited to: heart rate, respiration rate, temperature, pressure, chemical composition of fluid, e.g., analyte detection in blood, fluid state, blood flow rate, accelerometer motion data, IEGM (intra cardiac electrogram) data, etc.

[057] Accordingly, the receiver 100 may include physiological parameter measuring tools that allows it to determine if the subject is simply laying down or if the subject has suffered some medical condition that has caused them to end-up in that position. For example, the subject may have had a heart attack and the receiver 100 can detect that condition and in conjunction with information from the accelerometer 212, the receiver 100 is able to determine that the patient has a potentially serious medical condition. Another example would include the instant where the subject suffers from an epileptic seizure. The accelerometer 212 would provide information to the receiver 100 and the information from the accelerometer 212 combined with the measured physiological parameters would allow the receiver 100 to determine that a medical condition is taking place that will require immediate attention.

[058] Referring now to FIG. 1 B, the power management module 208 includes a high power operation module 300, an intermediate power operation module 302, and a low power operation module 304. The power management module 208 controls the power supplied to the components of the receiver 100 through the beacon switching module 306. The beacon switching module 306 generates a signal that allows the power management module 208 to transition the state of the receiver from active to active non-operation to inactive state depending on the information provided by the various modules and unit of the receiver 100.

[059] As discussed above, in the embodiment set forth in FIG. 1 , the receiver 100 may move from one state to another depending on the information provided by the environment. At an idle or inactive state the receiver 100 is not performing any active function and remains idle. The receiver 100 may transition between inactive state and other states depending on the required function(s) to be performed. Depending on the function, the intermediate power operation module may cycle the receiver 100 between the inactive state (e.g., idle) and the active state. For example, when the receiver 100 transitions from inactive state to detecting or active non-operational in order to collect ECG and/or accelerometer data, the intermediary module cycles the receiver 100 from an inactive (such as idle) state to an active state. When the receiver 100 is done collecting the ECG and accelerometer data, the intermediary module cycles the receiver 100 back to an inactive (such as idle state), and the receiver 100 returns to inactive state.

[060] When the receiver 100 transitions from inactive state to a sniff state for active non-operational condition in order to scan for data transmission signals (for examples by using a sniff module, such as described in greater detail below) associated with ionic emission for producing current flow with the data transmission encoded as a part thereof or for detection of data transmission associated with wireless communication, the intermediary module cycles the receiver 100 from an inactive (such as idle) state to an active non-operational state. If the receiver 100 receives a signal during this scanning or sniffing period, the receiver 100 then goes to active operational state and the high power operation module 300 of FIG. 1 B supplies high power to the operation unit 202, the processing unit 204, and the memory unit 206 all of FIG. 1 A. Then the receiver 100 processes the signal, e.g., demodulates, time-stamps and stores the signal as described in greater detail below, at the active operational state. When the receiver 100 completes processing the signal, the power management module 208 cycles the receiver 100 back to the inactive (such as idle state), and the receiver 100 returns to the inactive state.

[061] In some aspects, scanning for data transmission signals from a communication module within the subject 102 of Fig. 1 , such as the active non-operation state 130, the receiver 100 does not require high power to be cycled to the active non-operational state. In such cases the high power demand is not needed until a signal is detected for demodulation and decoding.

[062] In accordance with the teaching of the present invention, the signal receiver aspects of the receiver 100 may be configured to receive a conductively transmitted signal. The conductively transmitted signal may be a signal that is conductively transmitted signal by any physiologic part of the body or from a device that conductively transmits a signal through a body using ionic emission through controlled release of mass from solid into a conducting solution or fluid. The signal may be produced by an ionic emission module or an ingestible event marker (IEM) or a smart-parenteral delivery system. Ingestible event markers of interest include those described in PCT application serial no. PCT/US2006/016370 published as WO/2006/1 16718; PCT application serial no. PCT/US2007/082563 published as WO/2008/052136; PCT application serial no. PCT/US2007/024225 published as WO/2008/063626; PCT application serial no. PCT/US2007/022257 published as WO/2008/066617; PCT application serial no. PCT/US2008/052845 published as WO/2008/095183; PCT application serial no. PCT/US2008/053999 published as WO/2008/101 107; PCT application serial no. PCT/US2008/056296 published as WO/2008/1 12577; PCT application serial no. PCT/US2008/056299 published as WO/2008/1 12578; and PCT application serial no. PCT/US2008/077753 published as WO 2009/042812; the disclosures of which applications are herein incorporated by reference. Smart parenteral delivery systems are described in PCT application serial no. PCT/US2007/015547 published as WO 2008/008281 ; each of the foregoing disclosures is herein incorporated by reference in its entirety. 3] As the receiver of these aspects is configured to receive data encoded in current flow through a conductive fluid, the receiver and the device that emits the signal (such as an IEM) use the living body with which they are associated as a communication medium. To employ the body as a communication medium for the signal, the body fluids act as the conducting fluid and the body of the patient is used as a conduction medium for communication. As such, the signal that is transferred between ionic emission device and any other signal emitting device and the receiver, such as the receiver 100 of Fig. 1 , travels through the body of the subject 102. The conductively transmitted signal of interest may be transmitted through and received from the skin and other body tissues of the subject body in the form of electrical alternating current (a.c.) signals that are conducted through the body tissues. As a result, such receivers do not require any additional cable or hard wire connection between the device emitting the signal and the receiver.

[064] As the signal receivers are configured to receive a conductively transmitted signal, they may include a transbody conductive communication module. The transbody conductive communication module is a functional module that is configured to receive a conductively transmitted signal, such as a signal emitted by an IEM. Where desired, the transbody conductive communication module may be implemented by a high power functional block, such as described above. In some instances, the signal which the transbody conductive communication module is configured to receive is an encoded signal, by which is meant that the signal has been modulated in some manner (for example using a protocol such as binary phase shift keying (BPSK), frequency shift keying (FSK), amplitude shift keying (ASK), etc.). In such instances, the receivers and transbody conductive communication module thereof are configured to decode a received encoded signal, such as a signal emitted by an ingestible event marker. The receivers may be configured to decode the encoded signal in a low signal to noise ratio (SNR) environment, e.g., where there may be substantial noise in addition to the signal of interest, e.g., an environment having an SNR of 7.7 dB or less. The receivers may be further configured to decode the encoded signal with substantially no error. In certain aspects, the signal receiver has a high coding gain, e.g., a coding gain ranging from 6 dB to 12 dB, such as a coding gain ranging from 8dB to 10 dB, including a coding gain of 9 dB. The signal receivers of aspects of the invention can decode encoded signals with substantially no error, e.g., with 10% error or less.

[065] In those aspects where the received signal is encoded, such as where the received signal is an encoded IEM signal, the transbody conductive communication module may be configured to process the received signal with at least one demodulation protocol, where the transbody conductive communication module may be configured to process the received signal with two or more, three or more, four or more, etc., different demodulation protocols, as desired. When two or more different demodulation protocols are employed to process a given encoded signal, the protocols may be run simultaneously or sequentially, as desired. The received signal may be processed using any convenient demodulation protocol. Demodulation protocols of interest include, but are not limited to: Costas Loop demodulation (for example, as described in PCT Application Serial No. PCT/US07/024225 and published as WO 2008/063626, the disclosure of which is herein incorporated by reference); coherent demodulation (for example, as described in PCT Application Serial No. PCT/US07/024225 and published as WO 2008/063626, the disclosure of which is herein incorporated by reference); accurate, low overhead iterative demodulation (for example, as described in PCT Application Serial No. PCT/US07/024225 and published as WO 2008/063626, the disclosure of which is herein incorporated by reference); incoherent demodulation; and differential coherent demodulation.

[066] In some instances, a coherent demodulation protocol is employed. Coherent demodulation modules that may be employed in aspects of the receivers include, but are not limited to, those described in PCT Application Serial No. PCT/US2007/024225; the disclosure of which is herein incorporated by reference.

[067] In some instances, a differential coherent demodulation protocol is employed. Differentially coherent demodulation compares the phase of adjacent bits in a Binary phase-shift keying modulated signal (BPSK). For example an 8 bit binary code of 1 1001010 would result in a differential signal of 0101 1 1 1 . Since the technique leverages phase differences between adjacent bits, it is inherently more robust against signal frequency instability and drift than a coherent demodulation scheme.

COHERENT DEMODULATION

[068] The demodulation of BPSK in the presence of AWGN (Additive White Gaussian Noise) is performed in certain embodiments to minimize BER (Bit Error Rate) using coherent demodulation.

[069] In these embodiments, the in vivo transmitter facilitates the receiver coherent demodulation process by sending a pilot carrier in the "front porch" of each burst of BPSK modulation. This protocol provides a stable carrier at full amplitude and a reference phase that corresponds with the transmission of a 0 bit. The presence of a front porch gives a useful detection signature to the receiver and a large number of carrier cycles for accurate estimation of the carrier frequency and phase.

[070] An additional practical use is made of the carrier frequency to simplify derivation of the data rate. The transmitted signal is formatted to have the data clock frequency an integer division of the carrier frequency. This permits easy and rapid data clock acquisition once the carrier acquisition has been accomplished.

[071] The receiver samples the incoming signal at a rate of around 4 times the carrier frequency in certain embodiments. This signal is mixed with a DDS (Direct Digital Synthesizer) set to the nominal carrier frequency to create complex baseband (real and imaginary components). The output of the mixer is low pass filtered and decimated. The low pass filter bandwidth must be sufficiently wide to capture frequencies in the band due to carrier oscillator uncertainty and frequency hopping dither. The frequency of the BPSK is subsequently in the vicinity of 0 Hz with a frequency accuracy of +/- 20%.

[072] The receiver squares the complex baseband BPSK signal to create a strong double frequency line. The front porch signal and following BPSK modulation all contribute to this line. The squared complex time domain signal is transformed to the frequency domain using an FFT (Fast Fourier Transform). The peak energy bin is identified as the 2x carrier frequency. This frequency is divided by two to provide an estimate of the carrier offset frequency to about 0.1 % accuracy using a 1024 point FFT.

[073] The complex baseband signal is then mixed a second time with the determined offset frequency. The result after narrow band low pass filtering is a complex BPSK signal centered at 0 Hz with an accuracy of 0.1 %. The bandwidth of the narrow band low pass filter corresponds with the half bandwidth of the BPSK signal.

[074] The front porch signal is then extracted. The frequency offset is determined by first computing the phase (phi = arctan(imag/real)) of all sample points in the front porch, and then estimating the slope of phi vs. time using a least mean square fit to a line. The slope of the line corresponds to the residual frequency offset. The complex baseband signal is then mixed a third time to remove this frequency offset with an accuracy better than 0.01 %.

[075] The complex signal front porch is then averaged to determine the mean imaginary and real values. The arctan(mean imag/mean real) provides the front porch phase. A rotator factor is computed based on this phase to rotate the BPSK on to the imaginary axis with the front porch at 270 degrees.

[076] A second averaging is then performed on the entire rotated BPSK signal to identify the center of gravity of the 90 degree (data =1 ) and the BPSK is rotated in a similar manner to center this on the imaginary axis. The imaginary signal is then sliced to extract the data.

[077] The sliced data is strobed with a data clock that is derived from the prior determination of the carrier frequency and apriori knowledge of the integer factor relating the carrier frequency to the data clock frequency.

[078] In embodiments of the above protocols, it is assumed that the carrier frequency holds to a sufficient accuracy in frequency and phase through the duration of the entire burst.

[079] Aspects of Coherent Demodulation modules that may be employed in embodiments of the receivers include, but are not limited to, those described in PCT Application Serial No. PCT/US2007/024225; the disclosure of which is herein incorporated by reference.

ACCURATE, LOW OVERHEAD ITERATIVE DECODING

[080] In certain embodiments, the receivers include an accurate, low overhead interactive decoder, also referred to herein as a communications decoder. The communications decoder provides highly accurate communications in a simple, elegant, and cost-effective manner despite the presence of significant signal distortion due to noise and other factors. The communications decoder utilizes error correcting codes and a simple, iterative process to achieve the decoding results. The communications decoder can be used across multiple and varied applications to realize a low cost, high coding gain.

[081] Broadly, an embodiment of a communications decoder provides decoding capabilities for data communications. An embodiment of a communications decoder provides a high coding gain with minimal overhead. In some instances, the communications decoder facilitates data transmission rates close to the theoretical maximum, the Shannon Limit, while minimizing processing overhead. The low overhead ensures cost- effective implementations. Various implementations of the present invention include hardware, software, and circuitry.

[082] Various embodiments of the inventive communications decoder of the present invention use error correcting codes and a simple, unique process to "urge" a measurement signal associated with a bit in error toward a measurement signal associated with the correct, original bit, thus improving the likelihood of identifying destination data that matches the data encoded at origin and significantly improving data accuracy at destination. The simple, unique process facilitates efficient implementations. The low overhead associated with the simple, unique process minimizes costs. LDPC decoding is far less complex by using the iterative communications decoder of the present invention.

[083] Generally, the decoder module generates the decoded data via variations of the following technique. For each bit set of the encoded data, a set of measured signals associated with the encoded data is rounded to the nearest most likely possible measurement if no noise were present, e.g., to a nearest transmission symbol. The set of transmission symbols is converted into a set of hard code decision values. An error check is performed on the set of hard code decision values. The set of measured signals is adjusted based on an outcome of the error check of the set of hard code decision values. The foregoing is performed in passes across all measured signal sets of the encoded data until a predetermined stopping condition is met. Aspects of Accurate, Low Overhead Iterative Decoding modules that may be employed in embodiments of the receivers include, but are not limited to, those described in PCT Application Serial No. PCT/US2007/024225; the disclosure of which is herein incorporated by reference.

FORWARD ERROR CORRECTION

[084] In certain embodiments, the receiver is configured for use with an in vivo transmitter that employs FEC (Forward Error Correction) to provide additional gain to combat interference from other unwanted signals and noise. The error correction is simple in the transmitter and receiver, and provides high coding gain. This functionality is achieved using single parity check product codes and a novel SISO (Soft In Soft Out) iterative decoding algorithm.

[085] The transmitter encodes the message by arranging it in rows and columns. Each row has an appended parity bit, and similarly each column has an appended parity bit. For example, a 100 bit message could be arranged in a 10 by 10 bit array. Parity bits would be added to create a final 1 1 by 1 1 bit array that would then be transmitted on the channel using BPSK. For additional gain, additional dimensions could be used, such as three if a cube were created to arrange the message and parity bits.

[086] The receiver decodes the message by an iterative process to achieve high coding gain. Each bit is sampled and saved in "soft" form. Assuming ideal samples (i.e., hard decision points) are normalized to -1 and +1 , received bits would come in a range between say, -2.0 and +2.0. A hard decision is made on all samples and parity checked. If a row or column has a parity error, the samples of that row or column are repulsed from their corresponding hard decision point by a small delta. If the row or column has no parity error, the samples of that row or column are attracted to their corresponding hard decision point by a small delta. Using a properly selected delta, based on expected channel SNR (Signal to Noise Ratio), ten iterations is usually sufficient to achieve an 8 to 10 dB coding gain on AWGN (Additive White Gaussian Noise). This method is easy to implement in stored program DSP or FPGA/ASIC logic. It also comes within one or two dB of the Shannon limit for forward error correction given the particular coding rate.

[087] Aspects of Forward Error Correction modules that may be employed in embodiments of the receivers include, but are not limited to, those described in PCT Application Serial No. PCT/US2007/024225 published as WO 2008/063626; the disclosure of which is herein incorporated by reference.

BEACON FUNCTIONALITY MODULE

[088] Various aspects may employ the beacon functionality module. In various aspects, the beacon functionality sub-module may employ one or more of the following: a beacon wakeup module, a beacon signal module, a wave/frequency module, a multiple frequency module, and a modulated signal module.

[089] The beacon functionality module may be associated with beacon communications, e.g., a beacon communication channel, a beacon protocol, etc. For the purpose of the present disclosure, beacons are typically signals sent either as part of a message or to augment a message (sometimes referred to herein as "beacon signals"). The beacons may have well-defined characteristics, such as frequency. Beacons may be detected readily in noisy environments and may be used for a trigger to a sniff circuit, such as those described above.

[090] In one aspect, the beacon functionality module may comprise the beacon wakeup module, having wakeup functionality. Wakeup functionality generally comprises the functionality to operate in high power modes only during specific times, e.g., short periods for specific purposes, e.g., to receive a signal, etc. An important consideration on a receiver portion of a system is that it be of low power. This feature may be advantageous in an implanted receiver, to provide for both small size and to preserve a long-functioning electrical supply from a battery. The beacon wakeup module may enable these advantages by having the receiver operate in a high power mode for very limited periods of time. Short duty cycles of this kind can provide optimal system size and energy draw features.

[091] In practice, the receiver may "wake up" periodically, and at low energy consumption, to perform a "sniff function" via, for example, a sniff circuit. For the purpose of the present application, the term "sniff function" generally refers to a short, low-power function to determine if a transmitter is present. If a transmitter signal is detected by the sniff function, the device may transition to a higher power communication decode mode. If a transmitter signal is not present, the receiver may return, e.g., immediately return, to sleep mode. In this manner, energy is conserved during relatively long periods when a transmitter signal is not present, while high- power capabilities remain available for efficient decode mode operations during the relatively few periods when a transmit signal is present.

[092] Several modes, and combination thereof, may be available for operating the sniff circuit. By matching the needs of a particular system to the sniff circuit configuration, an optimized system may be achieved.

[093] Further examples of beacon functionality modules are described in PCT Application Serial No. PCT/US08/85048; the disclosure of which is herein incorporated by reference.

FREQUENCY HOPPING FUNCTIONALITY MODULE

[094] Various aspects may employ frequency hopping functionality module. The frequency hopping functionality module may be associated with the specific communications channel(s), frequency hopping protocol, etc. As such, various aspects may utilize one or more frequency hopping protocols. For example, the receiver may search the designated range of frequencies, e.g., two or more different frequencies, in which the transmission could fall. When a single proper decode is achieved, the in vivo transmitter has accomplished its mission of communicating its digital information payload to the receiver.

[095] In some instances, a transmitted frequency uncertainty provided by random frequency hopping, e.g., via a random module, may create multiple benefits. One example of such a communication protocol is frequency hopping spread spectrum communication (FHSS). FHSS is a method of transmitting radio signals by rapidly switching a carrier among many frequency channels, using a pseudorandom sequence known to both the transmitter and the receiver. One such benefit, for example, may be easy implementation on a small die. To illustrate, the in vivo transmitter carrier frequency oscillator can be an inaccurate free running oscillator that is easily implemented on a small portion of a 1 mm die. Accuracies on the order of +/- 20 are easily tolerated. This is because the receiver employs frequency searching algorithms.

[096] Another such benefit may be extended battery life. To illustrate, over the course of the transmitter battery life, e.g., three to ten minutes, the probability of the transmitter transmitting on a clear channel that can be received by the frequency agile receiver may be significantly enhanced due to random frequency hopping.

[097] Still another benefit may be minimized collision events in high volume environments. To illustrate, minimization of collision probability when multiple in vivo transmitters, e.g., ingestible event markers, are potentially transmitting simultaneously, such as in instances where the multiple ingestible event markers are ingested concurrently or in close temporal proximity. Stated differently, without frequency hopping functionality, there may be a high probability that ingestible event markers of a similar lot will transmit on the same (or nearly the same) frequency, resulting in multiple collisions.

[098] In certain aspects, the useful frequency spectrum for use in volume conduction applications ranges from about 3 kHz to 150 kHz. Through detailed animal studies it has been observed that in some environments, the in vivo transmitter, supra, having a received signal level in the range of 1 to 100 μV may compete with narrow band interfering signals on the order of hundreds to thousands of μV in the same frequency spectrum. To mitigate the destructive nature of interfering signals, a frequency hopping channel or protocol may be employed in which the in vivo transmitter randomly frequency hops a narrow band transmitted signal, e.g., a modulated signal such as a binary phase shift keying (BPSK) signal or FSK signal, output on each transmission.

[099] Further examples of Frequency Hopping modules are described in PCT Application Serial No. PCT/US08/85048; the disclosure of which is herein incorporated by reference.

COLLISION AVOIDANCE FUNCTIONALITY MODULE

[0100] Various aspects may employ a collision avoidance functionality module. The collision avoidance functionality module may be associated with the specific communications channel(s), collision avoidance protocols, etc. As such, various aspects may utilize various collision avoidance protocol techniques associated with the specific communications channel(s). Collision avoidance techniques may be particularly useful, for example, in environments where two or more in vivo transmitters are present, e.g., where an individual ingests multiple IEMs. In such an environment, if the various in vivo transmitters send their signals continuously, the transmission of one may obscure the transmission from all the other in vivo transmitters. As a result, failure to detect signals may increase significantly.

[0101] Various aspects may include various collision avoidance approaches, alone or in various combinations.

[0102] One such approach employs multiple transmit frequencies. By using frequency-selective filtering, the transmitter broadcasting at f1 can be distinguished from the transmitter broadcasting at f2, even if they are transmitting simultaneously.

[0103] Further examples of Collision Avoidance modules are described in PCT Application Serial No. PCT/US08/85048; the disclosure of which is herein incorporated by reference. PHYSIOLOGICAL SENSING

[0104] In addition to receiving a conductively transmitted signal, such as one emitted by an identifier of an ingestible event marker, the signal receiver may further include one or more distinct physiological parameter sensing abilities. By physiological parameter sensing ability is meant a capability of sensing a physiological parameter or biomarker, such as, but not limited to: cardio-data, including heart rate, electrocardiogram (ECG), and the like; respiration rate, temperature; pressure; chemical composition of fluid, e.g., analyte detection in blood, fluid state, blood flow rate, accelerometer motion data, etc. Where the signal receiver has physiological parameter or biomarker sensing capability, the number of distinct parameters or biomarkers that the signal receiver may sense may vary, e.g., 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, etc. The term "biomarker" refers to an anatomic, physiologic, biochemical, or molecular parameter associated with the presence and severity of specific disease states. Biomarkers are detectable and measurable by a variety of methods including physical examination, laboratory assays and medical imaging. Depending on the particular embodiment, the signal receiver may accomplish one or more of these sensing functions using the signal receiving element, e.g., using electrodes of the receiver for signal receiving and sensing applications, or the signal receiver may include one or more distinct sensing elements that are different from the signal receiving element. The number of distinct sensing elements that may be present on (or at least coupled to) the signal receiver may vary, and may be 1 or more, 2 or more, 3 or more, 4 or more, 5 or more, 10 or more, etc.

[0105] In certain embodiments, the signal receiver includes a set of 2 or more, such as 2 or 3, electrodes that provide for dual functions of signal receiving and sensing. For example, in addition to receiving signal, the electrodes can also serve additional sensing functions. In certain embodiments, the electrodes are used to generate electrocardiogram data. From that data, there are many kinds of processing that can be done, e.g., to detect various cardiac events, such as tachycardia, fibrillations, heart rate, etc. The obtained electrocardiogram data can be used to titrate medications, or be used for alerts when an important change or significant abnormality in the heart rate or rhythm is detected. This data is also helpful in certain embodiments for monitoring heart rate in patients who do not have pacemakers or as an alternative to patients who might normally require a Holter monitor or a Cardiac Event Monitor, portable devices for continuously monitoring the electrical activity of the heart for 24 hours or other devices. An extended recording period is useful for observing occasional cardiac arrthymias that are difficult to identify in shorter time periods. 06] As described above, two or more different demodulation protocols may be employed to decode a given received signal. In some instances, both a coherent demodulation protocol and a differential coherent demodulation protocol may be employed. FIG. 2 provides a functional block diagram of how a receiver may implement a coherent demodulation protocol, according to one aspect of the invention. It should be noted that only a portion of the receiver is shown in FIG. 2. FIG. 2 illustrates the process of mixing the signal down to baseband once the carrier frequency (and carrier signal mixed down to carrier offset) is determined. A carrier signal 221 is mixed with a second carrier signal 222 at mixer 223. A narrow low-pass filter 220 is applied of appropriate bandwidth to reduce the effect of out-of-bound noise. Demodulation occurs at functional blocks 225 in accordance with the coherent demodulation scheme of the present invention. The unwrapped phase 230 of the complex signal is determined. An optional third mixer stage, in which the phase evolution is used to estimate the frequency differential between the calculated and real carrier frequency can be applied. The structure of the packet is then leveraged to determine the beginning of the coding region of the BPSK signal at block 240. Mainly, the presence of the sync header, which appears as an FM porch in the amplitude signal of the complex demodulated signal is used to determine the starting bounds of the packet. Once the starting point of the packet is determined the signal is rotated at block 250 on the IQ plane and standard bit identification and eventually decoded at block 260. [0107] In addition to demodulation, the transbody communication module may include a forward error correction module, which module provides additional gain to combat interference from other unwanted signals and noise. Forward error correction functional modules of interest include those described in PCT Application Serial No. PCT/US2007/024225; the disclosure of which is herein incorporated by reference. In some instances, the forward error correction module may employ any convenient protocol, such as Reed-Solomon, Golay, Hamming, BCH, and Turbo protocols to identify and correct (within bounds) decoding errors.

[0108] Receivers of the invention may further employ a beacon functionality module. In various aspects, the beacon switching module 306 may employ one or more of the following: a beacon wakeup module, a beacon signal module, a wave/frequency module, a multiple frequency module, and a modulated signal module.

[0109] The beacon switching module 306 of Fig. 1 B may be associated with beacon communications, e.g., a beacon communication channel, a beacon protocol, etc. For the purpose of the present disclosure, beacons are typically signals sent either as part of a message or to augment a message (sometimes referred to herein as "beacon signals"). The beacons may have well-defined characteristics, such as frequency. Beacons may be detected readily in noisy environments and may be used for a trigger to a sniff circuit, such as described below.

[0110] In one aspect, the beacon switching module 306 may comprise the beacon wakeup module, having wakeup functionality. Wakeup functionality generally comprises the functionality to operate in high power modes only during specific times, e.g., short periods for specific purposes, to receive a signal, etc. An important consideration on a receiver portion of a system is that it be of low power. This feature may be advantageous in an implanted receiver, to provide for both small size and to preserve a long-functioning electrical supply from a battery. The beacon switching module 306 enables these advantages by having the receiver operate in a high power mode for very limited periods of time. Short duty cycles of this kind can provide optimal system size and energy draw features. [0111] In practice, the receiver 100 may "wake up" periodically, and at low energy consumption, to perform a "sniff function" via, for example, a sniff circuit. For the purpose of the present application, the term "sniff function" generally refers to a short, low-power function to determine if a transmitter is present. If a transmitter signal is detected by the sniff function, the device may transition to a higher power communication decode mode. If a transmitter signal is not present, the receiver may return, e.g., immediately return, to sleep mode. In this manner, energy is conserved during relatively long periods when a transmitter signal is not present, while high- power capabilities remain available for efficient decode mode operations during the relatively few periods when a transmit signal is present. Several modes, and combination thereof, may be available for operating the sniff circuit. By matching the needs of a particular system to the sniff circuit configuration, an optimized system may be achieved.

[0112] FIG. 3A illustrates a beacon switching module 306 wherein a sniff period 301 is longer than a transmit signal repetition period 303. The time function is provided on the x axis. As shown, the transmit signal repeats periodically, with a sniff function also running. In practice, effectively, the sniff period 301 may be longer than the transmit signal repetition period 303. In various aspects, there may be a relatively long period of time between the sniff periods. In this way, the sniff function, e.g., implemented as a sniff circuit, is guaranteed to have at least one transmission to occur each time the sniff circuit is active.

[0113] Referring now to FIG. 3B illustrates the beacon switching module 306 wherein a short but frequent sniff period 305 and a long transmit packet 307 are provided. The sniff circuit will activate at some point during the transmit time. In this manner, the sniff circuit may detect the transmit signal and switch into a high power decode mode.

[0114] An additional beacon wakeup aspect is to provide the "sniffing" function in a continuous mode. In contrast to the approaches provided above, this aspect of the transbody beacon transmission channel may exploit the fact that the total energy consumption is the product of average power consumption and time. In this aspect, the system may minimize the total energy consumption by having very short periods of activity, in which case the periods of activity are averaged down to a small number. Alternately, a low continuous sniff activity is provided. In this case, the configuration provides a sufficiently low power so that the transmission receiver runs continuously with total energy consumption at an appropriate level for the parameters of a specific system. 15] A functional flow diagram of the beacon switching module 306 of Fig. 1 B is shown in FIG. 3C. In FIG. 3C, the beacon switching module is shown as sniff module 310. The sniff module 310 is configured to scan for data encoded in current flow produced by ionic emission. The data is received at the receiver as a conductive signal at a set schedule, e.g., every 20 seconds. At step 315, the period during active sniff is limited, e.g., 300 msec. This relatively low duty-cycle allows for lower average power functionality for extended system life. At step 320, the receiver determines if a signal is present and if that signal has a valid ID. If no signal having a valid ID is detected during active sniff (as illustrated by arrow 320), the process returns to step 315 and the active sniff is turned off until the next predetermined active period. If at step 320 a signal having a valid ID is received, then the process moves to step 322. At step 322, the receiver determines if the signal received is from a previously detected ionic transmitter. If the signal is from a previously detected ionic transmitter, then the process moves to step 326. At step 326 the receiver determines whether the count (in other words, individual valid detections of the same ID) in the current wake up cycle (specified time since the last reported ID, such as 10 minutes) is greater than a specified number (such as 50) as measured by a threshold counter. If the count exceeds this threshold as determined by the threshold counter, the receiver returns to sniff mode. If the count does not exceed the threshold value, then the process moves to step 330 and the receiver operates in 100% detection mode to analyze the received data encoded in the current flow by the ionic emission. Once the received data is decoded and analyzed, the process return to step 315. If at step 322, the receiver determines that the data encoded in the current flow is coming from a different valid source than previously detected, then the process moves to step 328. At step 328 the threshold counter is reset.

[0116] Another view of a beacon module is provided in the functional block diagram shown in FIG. 3D. The scheme outlined in FIG. 3D outlines one technique for identifying a valid beacon. The incoming signal 360 represents the signals received by electrodes, bandpass filtered (such as from 10 KHz to 34 KHz) by a high frequency signaling chain (which encompasses the carrier frequency), and converted from analog to digital. The signal 360 is then decimated at block 361 and mixed at the nominal drive frequency (such as, 12.5 KHz, 20 KHz, etc.) at mixer 362. The resulting signal is decimated at block 364 and low-pass filtered (such as 5 KHz BW) at block 365 to produce the carrier signal mixed down to carrier offset-signal 369. Signal 369 is further processed by blocks 367 (fast Fourier transform and then detection of two strongest peaks) to provide the true carrier frequency signal 368. This protocol allows for accurate determination of the carrier frequency of the transmitted beacon.

[0117] FIG. 4 illustrates a beacon functionality wherein a beacon is associated with one frequency, e.g., a beacon channel, and a message is associated with another frequency, e.g., a message channel. This configuration may be advantageous, for example, when the system is dealing with multiple transmit signals. The solid line represents the beacon from Transmit Signal 1 . The dashed line represents the beacon from Transmit Signal 2. In various transmission situations, the Transmit Signal 2's beacon might overlap with that of Transmit Signal 1 , as depicted. Message Signal 1 and Message Signal 2 can be at different frequencies from their respective beacons. One advantage may be that the beacon from Transmit Signal 2 does not interfere with the message from Transmit Signal 1 at all, even though they are transmitted at the same time. While 4 is shown with two transmitters, it will be apparent to one of ordinary skill in the art to modify the system so as to scale it to many more transmitters. The requirements of a particular system may, to some extent, dictate the particular architecture of that system. [0118] Further examples of beacon functionality modules are described in PCT Application Serial No. PCT/US08/85048; the disclosure of which is herein incorporated by reference.

[0119] Various aspects may employ a frequency hopping functionality module. The frequency hopping functionality module may be associated with the specific communications channel(s), frequency hopping protocol, etc. As such, various aspects may utilize one or more frequency hopping protocols. For example, the receiver may search the designated range of frequencies, e.g., two or more different frequencies, in which the transmission could fall. When a single proper decode is achieved, the in vivo transmitter has accomplished its mission of communicating its digital information payload to the receiver.

[0120] In some instances, a transmitted frequency uncertainty provided by random frequency hopping, e.g., via a random module, may create multiple benefits. One such benefit, for example, may be easy implementation on a small die. To illustrate, an in vivo transmitter carrier frequency oscillator can be an inaccurate free running oscillator that is easily implemented on a small portion of a 1 mm die. Accuracies on the order of +/- 20 are easily tolerated because the receiver employs frequency searching algorithms.

[0121] Another such benefit may be extended battery life. To illustrate, over the course of the transmitter battery life, e.g., three to ten minutes, the probability of the transmitter transmitting on a clear channel that can be received by the frequency agile receiver may be significantly enhanced due to random frequency hopping.

[0122] Still another benefit may be minimized collision events in high volume environments. To illustrate, minimization of collision probability when multiple in vivo transmitters, e.g., ingestible event markers, are potentially transmitting simultaneously, such as in instances where the multiple ingestible event markers are ingested concurrently or in close temporal proximity. Stated differently, without frequency hopping functionality, there may be a high probability that ingestible event markers of a similar lot will transmit on the same (or nearly the same) frequency, resulting in multiple collisions. [0123] In certain aspects, the useful frequency spectrum for use in volume conduction applications ranges from about 3 kHz to 150 kHz. Through detailed animal studies it has been observed that in some environments, the in vivo transmitter, supra, having a received signal level in the range of 1 to 100 μV may compete with narrow band interfering signals on the order of hundreds to thousands of μV in the same frequency spectrum. To mitigate the destructive nature of interfering signals, a frequency hopping channel or protocol may be employed in which the in vivo transmitter randomly frequency hops a narrow band transmitted signal, e.g., a modulated signal such as a binary phase shift keying (BPSK) signal or FSK signal, output on each transmission.

[0124] Further examples of Frequency Hopping modules are described in PCT Application Serial No. PCT/US08/85048; the disclosure of which is herein incorporated by reference.

[0125] Various aspects of the receivers may employ a collision avoidance functionality module. The collision avoidance functionality module may be associated with the specific communications channel(s), collision avoidance protocols, etc. As such, various aspects may utilize various collision avoidance protocol techniques associated with the specific communications channel(s). Collision avoidance techniques may be particularly useful, for example, in environments where two or more in vivo transmitters are present, e.g., where an individual ingests multiple IEMs. In such an environment, if the various in vivo transmitters send their signals continuously, the transmission of one may obscure the transmission from all the other in vivo transmitters. As a result, failure to detect signals may increase significantly.

[0126] Various aspects may include various collision avoidance approaches, alone or in various combinations.

[0127] One such approach employs multiple transmit frequencies. By using frequency-selective filtering, the transmitter broadcasting at f1 can be distinguished from the transmitter broadcasting at f2, even if they are transmitting simultaneously. [0128] Further examples of Collision Avoidance modules are described in PCT Application Serial No. PCT/US08/85048; the disclosure of which is herein incorporated by reference.

[0129] Additional functional modules that may be included in the transbody communication module of the receivers of the invention include a clock functionality module, which associates a particular time with a given signal, e.g., as described in one or more of PCT Application Serial No. PCT/US08/85048; PCT Application Serial No. PCT/US2007/024225 published as WO 2008/095183 and PCT Application Serial No. PCT/US2007/024225 published as WO 2008/063626; the disclosures of which are herein incorporated by reference.

[0130] As indicated above, the transbody conductive signal may also be a signal produced by smart parenteral delivery systems, e.g., as described in PCT application serial no. PCT/US2007/015547 published as WO 2008/008281 ; the disclosure of which is herein incorporated by reference. In these instances, the body-associate medical device may be configured to derive a number of different types of information about a fluid delivery event from the received signal. Types of information that may be derived include, but are not limited to: that the delivery event is about to occur or has occurred, how much fluid was administered, the identity of the fluid that was administered, etc. For those instances where the receiver is configured to determine how much fluid was administered, the device may be configured to receive variable volume administration data, such that it is configured to receive different values for this data field.

[0131] The receivers may provide a further communication path via which collected data can be transferred from the receiver to another device, such as but not limited to, a smart phone, hospital information system, etc. This further communication path is provided by an "extra-corporeal communication" module. This extra-corporeal communication module may employ a variety of different protocols. Protocols of interest include both wired and wireless communication protocols. For instance, a receiver may include conventional RF circuitry (for example, operating in the 405-MHz medical device band) with which a practitioner can communicate, e.g., by using a data retrieval device, such as a wand or analogous device. Of interest in some aspects are low power wireless communication protocols, such as BLUETOOTH™ wireless communication protocols. Also of interest are communications protocol that employ a multi-purpose connector, such as described in greater detail below.

[0132] Where the receiver includes at least a portion that is external to a living body during use, that portion may have output devices for providing, e.g., audio and/or visual feedback; examples of which include audible alarms, LEDs, display screens, etc. The external portion may also include an interface port via which the component can be connected to a computer for reading out data stored therein. In addition, the external portion may include one or more operation elements, such as buttons or analogous structures, that allow a user to manually interact with the body-associate medical device in some way, e.g., to test operability, to turn the device on, to reset the device, etc.

[0133] In some instances, an extra-corporeal communication module is employed to reconfigure various parameters of the receiver. As such, the communication module may be a two-way communication module. Parameters that may be re-configured include the "Duty Cycle" of the data acquisition, e.g., how often the receiver sniffs for IEMs, how often and for how long the receiver collects ECG or activity data, etc.

[0134] In one aspect, the extra-corporeal communication module may be implemented to have its own power supply so that it may be turned on and off independently from other components of the device, for example, by a microprocessor.

[0135] Receivers in accordance with the teachings of the invention may include one or more distinct physiological sensing modules. By physiological sensing module is meant a capability or functionality of sensing one or more physiological parameters or biomarkers of interest, such as, but not limited to: cardio-data, including heart rate, electrocardiogram (ECG), and the like; respiration rate, temperature; pressure; chemical composition of fluid, e.g., analyte detection in blood, fluid state, blood flow rate, accelerometer motion data, etc. Where the receiver has physiological parameter or biomarker sensing capability, the number of distinct parameters or biomarkers that the signal receiver may sense may vary, e.g., one or more, two or more, three or more, four or more, five or more, ten or more, etc. The term "biomarker" refers to an anatomic, physiologic, biochemical, or molecular parameter associated with the presence and severity of a health state, such as a specific disease state. Depending on the particular aspect, the device may accomplish one or more of these sensing functions using a signal receiving element of the device, such as by using electrodes of the receiver for signal receiving and sensing applications, or the receiver may include one or more distinct sensing elements (such as micro-needles described below) that are different from the signal receiving element. The number of distinct sensing elements that may be present on the (or at least coupled to the) signal receiver may vary, and may be one or more, two or more, three or more, four or more, five or more, ten or more, etc. 36] In certain aspects, the receiver includes a set of two or more, such as two or three, electrodes that provide for dual functions of signal receiving and sensing. For example, in addition to receiving signal, the electrodes can also serve additional sensing functions. In certain aspects, the electrodes are used to generate electrocardiogram data. From that data, there are many kinds of processing that can be done, e.g., to detect various cardiac events, such as tachycardia, fibrillations, heart rate, etc., to detect neurological conditions, such as seizures (e.g., as may occur in epilepsy (see for example devices and modules configured for seizure detection, described in greater detail below), etc. The obtained electrocardiogram data can be used to titrate medications, or can be used for to provide an alert when an important change or significant abnormality in the heart rate or rhythm is detected. These data are also helpful in certain aspects for monitoring heart rate in patients who do not have pacemakers or as an alternative to patients who might normally require a Holter monitor or a Cardiac Event Monitor, portable devices for continuously monitoring the electrical activity of the heart for 24 hours or other devices. An extended recording period is useful for observing occasional cardiac arrhythmias that are difficult to identify in shorter time periods. [0137] As mentioned above, one or more additional physiological sensors distinct from the electrodes may be included in the receiver. For example, a temperature sensor, such as a thermistor, CMOS temperature sensor, resistive temperature devices (RTDs), may be employed to obtain precise measurements of temperature. An additional physiological sensor may include an LED and a photodiode combined into a pulse oximeter, which may be employed to measure blood oxygenation, which would also give information about pulse pressure. In addition, aspects of the signal receivers include a pressure sensor, e.g., where the signal receiver is implanted next to an artery to get measurements of arterial blood pressure. Strain gauges are present in certain aspects to measure pressure deflections, which are then attached to the signal receiver.

[0138] The receivers may also include analyte detection sensors. For example, specific chemical sensors may be incorporated into the signal receivers to detect the presence of various agents, e.g., alcohol, glucose, BNP (B-type Natriuretic peptide, which is associated with cardiac disease), etc. Sensor of interest include those configured to detect the presence of a chemical analyte in a biological fluid sample, where analytes of interest include, but are not limited to: blood sugar (glucose), cholesterol, bilirubin, creatine, various metabolic enzymes, hemoglobin, heparin, hematocrit, vitamin K or other clotting factors, uric acid, carcinoembryonic antigen or other tumor antigens, various reproductive hormones such as those associated with ovulation or pregnancy, drugs of abuse and/or metabolites thereof; blood alcohol concentration, etc. In certain aspects, substances or properties for which the receiver is configured to detect include lactate (important for athletes), oxygen, pH, alcohol, tobacco metabolites, and illegal drugs (important for both medical diagnosis and law enforcement). Where the receiver includes an analyte detecting sensing element, this sensing element can be configured in the receiver in a number of different ways. For example, a sensor that includes a selectively permeable membrane which is permeable to the agent one wants to detect may be provided, where there is an isolated cell behind the membrane and the agent passes through the membrane. Changes in the properties, such as electrical properties, of the cell, are then measured. In certain aspects, a small reservoir on the side of the receiver with a membrane across it is employed, and electrical circuitry behind it is measured. Also of interest are ChemFET sensors, which are based on the binding of analyte to the sensor causing a change in the conductivity. In certain aspects, a material whose electrical properties (or other properties) are changed when the material, e.g., protein analyte, binds to it are employed. Blood alcohol concentration may be determined any number of ways, including but not limited to: sensors that analyze fluid samples, such as perspiration, optical spectroscopic sensors, etc.

[0139] Of interest are receivers that include at least an electrocardiography (ECG) sensor module. An ECG sensor module is a module which is configured to obtain ECG data and, if desired, additionally perform one or more of processing the data in some way, storing the data and retransmitting the data. The ECG data may be employed by the receiver to derive a number of different metrics, including but not limited to: R- wave, heart rate, heart rate variability, respiration rate, etc. Where the receiver includes one or more physiological sensing functionalities, the device may further include sensing modules that are configured to obtain and process data from these sensing functionalities. For example, where the receiver includes an ECG sensing functionality, the device may include an appropriate functional module (for example in the form of programming) that can handle and process the raw data from these sensors. An example of a physiological sensing module of interest is of an ECG sensing module as illustrated in FIG. 5.

[0140] Referring now to FIG. 5, an illustration of an ECG sensing module which implements a modified Hamilton and Tompkins algorithm is shown. FIG. 5 represents one possible implementation of an R-wave detection algorithm, according to one aspect of the invention. As illustrated in FIG. 5, the ECG sensing modules receives signals via electrodes and bandpasses those signals (e.g., 0.3 to 150 Hz) at filter 501 , before converting the signal to a digital signal at A/D converter 502. The signal is then sent to microprocessor 503 and on to digital signal processor 504 for processing. For example, the data signal received by the DSP 504 is bandpass filtered (e.g., at 10-30 Hz) at block 505, differentiated at block 510, and further filtered at block 515 to emphasize and eventually identify the window in which the QRS complex exists at block 520. Logic is then applied to identify the R-wave within each window. At logic block 525, it is determined if the window width is, for example, greater than 140ms. The peak and dip in the window is determined, as shown by logic block 530. If the peak is greater than twice the dip, then the R-wave is equal to the peak. If the dip is greater than twice the peak, then the R-wave is equal to the dip. Otherwise, the R-wave is equal to the ratio of the peak to the dip occurring first. This is shown by logic block 535. Thereafter, the R-wave amplitude and time-to-peak is sent to memory (e.g., flash), as shown by logic block 540.

[0141] Also of interest are accelerometer modules. An accelerometer module is a module which is configured to obtain accelerometer data and, if desired, additionally perform one or more of processing the data in some way, storing the data and retransmitting the data. The accelerometer module may be employed by the receiver to derive a number of different metrics, including but not limited to: data regarding patient activity, mean activity, patient position and angle, activity type, such as walking, sitting, resting (where this data may be obtained with a 3-axis accelerometer); and then save the obtained data. Of interest are both analog accelerometers and digital accelerometers. An example of an accelerometer module of interest is shown in FIG. 6.

[0142] Referring now to FIG. 6, a functional block diagram of a 3-axis accelerometer module that is configured to obtain and process accelerometer data from three different axes, according one aspect of the invention, is shown. Each axis of the accelerometer is processed to determine the mean (as shown at block 601 ), standard deviation (as shown at blocks 602), and auto-correlation (as shown at block 603). The mean is reflective of the orientation of the accelerometer with respect to gravity, whereas the standard deviation and autocorrelation are important metrics describing the amplitude and frequency of the observed motion, for example, peak correlation, associated frequency, and correlation between axes. In order to perform step-counting, the three axes are combined at block 630 and filtered at block 635. The total acceleration is constructed, as shown at block 640. The use of the total acceleration makes the system robust against different orientations of the receiver with respect to the subject. Once the total acceleration is computed the standard deviation and auto correlation are calculated, as shown at block 645. These values are then thresholded (for example standard deviation>0.1 and Auto-correlation >0.25) to determine whether significant, cyclic motion exists, as shown at block 650. Then, as shown at block 655, if the thresholded values are exceeded, the number of steps is determined as the number of zero-crossings of the mean corrected total acceleration.

[0143] In some receivers, the device may include an environmental functional module. Environmental functional modules are modules that are configured to or acquire data related to the environment of the receiver, e.g., the environmental conditions, whether the receiver is connected to a skin surface, etc. For example, the environmental functional module may be configured to obtain receiver ambient temperature data. The environmental functional module may be configured to determine electrode connection, e.g., by impedance measurement. The environmental functional module may be configured to determine battery voltage. The above specific functions of the environmental functional module are merely illustrative and are not limiting.

[0144] A receiver may be configured to handle received data in various ways. In some aspects, the receiver simply retransmits the data to an external device (e.g., using conventional RF communication). In other aspects, the receiver processes the received data to determine whether to take some action such as operating an effector that is under its control, activating a visible or audible alarm, transmitting a control signal to an effector located elsewhere in the body, or the like. In still other aspects, the receiver stores the received data for subsequent retransmission to an external device or for use in processing of subsequent data (e.g., detecting a change in some parameter over time). The receivers may perform any combination of these and/or other operations using received data.

[0145] In certain aspects where the receiver is an IEM signal receiver, the data that are recorded on the data storage element includes at least one of, if not all of, time, date, and an identifier (e.g., global unique serial no.) of each IEM administered to a patient, where the identifier may be the common name of the composition or a coded version thereof. The data recorded on the data storage element of the receiver may further include medical record information of the subject with which the receiver is associated, e.g., identifying information, such as but not limited to: name, age, treatment record, etc. In certain aspects, the data of interest include hemodynamic measurements. In certain aspects, the data of interest include cardiac tissue properties. In certain aspects, the data of interest include pressure or volume measurements, temperature, activity, respiration rate, pH, etc.

[0146] Receivers may include a variety of different types of power sources which provide operating power to the device in some manner. The nature of the power block module may vary. In some instances, the power block may include a battery. When present, the battery may be a onetime use battery or a rechargeable battery. For rechargeable batteries, the battery may be recharged using any convenient protocol. Of interest is a protocol that results in multi-tasking of elements of the receiver. For example, receivers of the invention may include one or more electrodes which are used for a variety of functions, such as receiving conductively transmitted signals, sensing physiological data, etc. The one or more electrodes, when present, may also be employed as power receivers which may be employed for recharging the rechargeable battery, e.g., as further described in the Multi-Purpose Connection Module section below. Alternatively, the power block may be configured to receive a power signal, e.g., where the power block comprises a coil which can impart power to the device when an appropriate magnetic field is applied to the receiver. In yet other instances, the device may include a body-powered power block, such as that described in United States Patent Application Serial No. 1 1/385,986, the disclosure of which is herein incorporated by reference.

[0147] The receiver may include a power supply module which controls when certain states are assumed by the device, e.g., in order to minimize device power usage. For example, the power supply module may implement a duty cycle for data collection based on time of day, or patient activity, or other events, where the implemented duty cycle may be based on a signal factor or multiple factors. For example, the power supply module may cause the receiver to obtain patient activity data (for example by an accelerometer module) when the patient is moving around and not when the patient is at rest. In other aspects, the power management module may have the receiver collect ECG data only at night, for example by using a real time clock in the receiver to collect ECG only in a predetermined time range, e.g., from 9PM to 7AM. 48] As stated earlier, the receiver may be configured to have various states — e.g., an idle state or one or more active states-with the intermediary module cycling the high power functional block between active and inactive states as needed for each desired receiver state. In addition, other receiver elements may be cycled on and off during different states of the receiver by a power supply module. The power supply module may be configured to control the power supply to various circuit blocks within the medical device — e.g., circuit blocks relating to power supply to processors, circuit blocks relating to various peripheral components (e.g., wireless communication module, etc.) and their power supplies, etc. Therefore, during each state of the receiver, the power supply to various components of the receiver may be independently cycled on and off as needed to achieve power efficiency (and independently from the cycling of the high power functional block between active and inactive states as discussed earlier). For example, in some instances, receivers may be configured to be present in two or more different active states, where a different task or set of tasks is performed in each different active state. The receivers of interest may be configured to perform an IEM signal detection protocol when present in a first active state and a physiological data detection protocol when present in a second active state. In these types of receivers, various components of the receiver may be independently cycled on and off as required to achieve power efficiency (and independently from the cycling of the high power functional block between active and inactive states as discussed earlier). [0149] The power supply module may comprise one or more individual power supplies to activate and deactivate power supply to these various components. For example, in one aspect, the power supply module may comprise a high power processing input/output power supply to supply input/output power to the high power processing block; and, a high power processing core power supply to supply core power to the high power processing block. Furthermore, the power supply module may comprise a wireless communication input/output power supply to supply input/output power to the wireless communication module; and, a wireless communication core power supply to supply core power to the wireless communication module.

[0150] It should be understood that a single power supply may be used to provide power to multiple components. For example, a single power supply may provide input/output power to both the high power processing block and to the wireless communication module. In one aspect, the power supply module receives control signals from a low power processing block (for example, the microprocessor) which determines which power supplies are turned on/off.

[0151] Referring now to FIG. 26, a circuit diagram of part of the receiver's circuitry in accordance with the teaching of the present invention is provided. The circuitry 2600 is responsible for controlling the power supply to various components of the receiver. FIG. 26 is connected to FIG. 24 at signal line "VCC_EN_BAT" shown in both figures, and works in conjunction with part of the circuit in FIG. 24 to control the power supplies. As illustrated in FIG. 26, translator 2610 is shown electrically coupled to switch 2620 which is electrically coupled to voltage references 2630 and 2640. Translator 2610 translates data signal VC_ENA on its A bus to signal VC_EN_BAT on its B bus. Signal VCC_EN_BAT is connected to the enable pins of regulators 24155, 24157, and 24159 (illustrated in FIG. 24) which supply power to various components. Therefore, data signal VCC_EN_BAT may enable/disable the power supply for various components of the receiver. For instance, regulator 24155, 24157, and 24159 provide power to the DSP core, DSP & wireless communication I/Os, and wireless communication core, respectively. Therefore, each of these components can be powered off and on with a corresponding enable/disable data signal (VCC_EN_BT) from circuitry 2600.

[0152] Receivers may include a multi-purpose connector module. A multipurpose connector module includes living subject contacts, such as electrodes, as described herein (also referred to hereinafter as "multipurpose connectors"), and may be used for periodic recharging of a power source of the device, reprogramming of a control function of the device and/or data retrieval from the device. This configuration is in contrast to configurations that include a separate connector for each of these functions, such as distinct patient connectors, power connectors and device configuration connectors.

[0153] Receivers that include multi-purpose connector modules are capable of variable connection between a target object, such as a patient or patient-related device, and a second external device, such as an external programming device and an external charger device. The connection may be used to facilitate communication of signals, e.g., electrical signals, digital signals, optical signals, combinations of various types of signals, etc. The term "variable connection", as used herein, refers to the capability of the multi-purpose connector to receive a connecting component associated with one of a living subject, such as a patient, and the second external device and to form a connection based on the specific connecting component, e.g., a connecting component associated with a patient or a connecting component associated with the second external device. The receiver further includes multiple functional blocks to control signals associated with a communication of signals via the connection. In various aspects, the second external device comprises an external programming device and the second functional block comprises a controller functional block to control signals associated with a communication between the external programming device and the receiver. When the receiver is connected to the external programming device via the multi-purpose connector, the external programming device may be used to programmatically control the receiver. In various aspects, the second external device comprises an external charger device and the second functional block comprises a power functional block to control signals associated with a communication between the external charger device and the receiver. When the receiver is connected to the external charger via the multi-purpose connector, the external charger may be used to charge the receiver. In various aspects, the second functional block comprises a patient interactive functional block. When the receiver is connected to the patient or to a patient-related device via the multipurpose connector, the device may be used to interactively communicate with the patient or patient-related device. For example, the receiver may be configured with electrodes to stimulate or sense various patient parameters and physically attached to the patient to facilitate various functional goals, e.g., deliver a pacing stimulation to the patient; receive physiologic information from the patient, etc.

[0154] In some aspects, at least one of the multiple functional blocks is configured as a signal director. The signal director may be any component, subcomponent, or combination thereof capable of carrying out the described functionality. In one example, the receiver is physically associated with, e.g., configured to include, the signal director. Such a configuration may comprise one or more circuits, etc. In another example, the signal director is physically distinct from the receiver. Such a configuration may comprise a router or other network device capable of facilitating the signal functionality described herein. The signal director may comprise a control element configured to control signals, e.g., discriminate the signals. In various aspects, the signal director comprises at least one of software and circuitry.

[0155] Signal control or discrimination may be based on various criteria, e.g., voltage, frequency, manual control, programmatic control, etc. Control element configuration varies accordingly. For example, a control element that discriminates based on voltage may be implemented as one or more diodes, a thermistor, etc. A control element that discriminates based on frequency may be implemented as a high-pass filter or as a low- pass filter. A control element providing manual and/or programmatic control may be implemented as an analog switch, a relay, a multiplexor, etc. Various other implementations may be based on various parameters such as light, temperature, time, etc. [0156] As indicated above, multi-purpose connectors are connector elements that are configured to provide connection to a patient and one or more second external devices, such as an external programming device, an external charger device, or an external data processor. Accordingly, the structure of the multi-purpose connector is such that it can provide connection of the receiver to a patient, either directly or through another device (as described below) and to another device. Accordingly, the receiver can be connected to a patient via the multi-purpose connector at a first time and to another device via the same multi-purpose connector at a second time that is different from the first time, such that the same multipurpose connector is employed to connect the receiver to different entities at different times. As such, the multi-purpose connector may be used to connect, at different times, one or more of the physical implementations of functional blocks of the device to the patient and to at least one or more additional external devices, such as an external charger, an external programming device, or an external data processor.

[0157] The structure of the multi-purpose connector may vary as desired, where connector structures of interest include, but are not limited to: IS-1 connectors, Association for the Advancement of Medical Instrumentation Electrocardiographic (AAMI ECG) cord connectors, and medical grade shrouded multi-pin connectors. In some instances, the connector includes one or more electrodes, such as two to ten electrodes, including three electrodes or four electrodes.

[0158] Where desired, the multi-purpose connector may be configured to connect directly with a patient or other external device, such that no additional connector device is required to provide connection between the multi-purpose connector of the receiver and the patient or other external device. Alternatively, the multi-purpose connector may be configured to connect to the patient or other external device through a physically distinct connector device, such as a cable or cord. The physically distinct electrical connector may have one termination configured to fit into the multi-purpose connector, and another termination configured to perform a specific purpose, such as connecting to a patient or an external device, such as a battery charger or external programming device. It should be noted that where a receiver connects to a patient via a distinct connector, such as wire, the device is still considered a receiver.

[0159] In receivers of the invention, the multi-purpose connector is operatively connected (such as electrically connected, optically connected, etc.) to multiple functional blocks (for example two or more, three or more, four or more, five or more, seven or more, ten or more functional blocks), e.g., as described elsewhere in the present application.

[0160] In addition to being configured to connect a patient, the multipurpose connectors of interest may be configured to connect the receiver to other external devices, including but not limited to external charger devices, external programming devices, data processing devices, modems, keyboards, displays, and/or external storage devices, etc. By using the same connector to connect the receiver to the patient and to other devices, connection of the patient to the receiver while the medical device is connected to another device, such as a charger, is avoided. This configuration enhances patient safety, because it eliminates the possibility that a signal from the other external device, such as the power charger, programming device, data processor, etc., will be transferred to the patient, potentially harming the patient. Using a single connector for multiple functions also makes waterproofing of the device easier because there are fewer openings on the housing of the device.

[0161] The receiver of interest may include a router functionally positioned between the multi-purpose connector and one or more of the multiple functional blocks of the device. By "functionally positioned between" is meant that a signal, such as an incoming signal, outgoing signal, or bidirectional signal, will, after passing through the multi-purpose connector, pass through the router before entering one of the multiple functional blocks. The router may be configured to selectively allow signals to pass through to certain functional blocks depending on one or more parameters. For example, the router may be configured to discriminate the signal based on voltage, e.g., allowing only voltage above or below a certain threshold (or within a certain band) to pass through; frequency, e.g., allowing only signals above or below a threshold frequency (or within a certain frequency band) to pass through; or operating mode, e.g., power- charging mode, data transmission mode, patient interactive mode, etc. In some instances, there may be a router functionally positioned between the multi-purpose connector and only some of the multiple functional blocks. In other words, there may be one or more functional blocks that are not separated from the multi-purpose connector by a router.

[0162] In some instances, the router may be configured to discriminate signals based on the unique characteristics of the signals of interest to the device. A signal measured from the body may be a relatively low voltage, for example 500 mV or less, such as 100 mV or less, or 50 mV or less. Similarly, a signal measured from the body may be of relatively low frequency, for example 20 kHz or less, such as 5 kHz or less, or 1 kHz or less. In comparison, a typical power signal used to recharge the internal battery of a device such as the external medical device may be a relatively higher voltage, such as 1 V or more, 2 V or more, or 5 V or more. A typical signal used for data transmission may have a relatively higher frequency than a body-measured signal, for example 100 kHz or more, such as 1 MHz or more, or 10 MHz or more. Thus, by distinguishing based on frequency and voltage, the router can selectively route a signal to the appropriate functional block or blocks. A router may discriminate the signal based on any characteristic of the signal, including but not limited to voltage, frequency, and the combination of the two. In other instances, the router can route the incoming signal based on the operating mode of the device, which may be set by other circuitry, by software, or by a manual switch or command.

[0163] In certain instances, the router is configured to route a certain type of signal to a particular functional block while isolating the signal from one or more other functional blocks. For example, if it is desired to make a high impedance measurement of the signal from the patient, it can be important to isolate the low impedance of the power functional block. In this case, a router can be placed between the power functional block and the multi-purpose connector which only allows a signal above a certain voltage to pass through. Thus, the relatively low voltage of a signal measured from the patient's body will be isolated from the power functional block, and the patient interactive functional block will be able to properly measure the signal.

[0164] However, in some instances, it may not be important to isolate a particular block from the other functional blocks when it is not being used. As such, in some instances the router may not be configured to disconnect one or more particular functional blocks from the signal. That is, in these instances, the incoming signal will always pass to a particular functional block. However, in some cases, the functional block may only respond to certain types of signals, such as a certain range of frequency or voltage, and will not suffer harm when exposed to other signals. This selective responsiveness may effectively act as a routing means.

[0165] The router, as used here, may itself be made up of multiple functional routing blocks, each one functionally positioned between one or more of the device functional blocks and the multi-purpose connector. In this way, the individual router blocks may discriminate the signal based on different parameters, allowing a different class of signal to reach the respective device functional blocks.

[0166] The router may route signals to the appropriate circuitry either inherently, actively, or by a combination of inherent and active techniques. In some instances, the routers may discriminate the incoming signal based on voltage. For example, a router functionally positioned between the multiple-purpose connector and one or more of the functional blocks may allow only a signal above a certain voltage threshold to pass through to those functional blocks. In some instances this may be done with one or more diodes. In some instances, the diodes may be arranged as a rectifier, e.g., a half-wave rectifier, full-wave rectifier, three phase rectifier, etc. In other instances, the router may allow only a signal below a certain threshold voltage to pass through to the associated functional blocks.

[0167] In other instances, the router may route signals based on frequency. For example, a router functionally positioned between the multiple-purpose connector and one or more of the functional blocks may allow only a signal above a certain frequency to pass through to the associated functional blocks. In other instances, the router may allow only a signal below a certain frequency, within a certain frequency band, or outside of a certain frequency band to pass through. A router that discriminates based on frequency may contain a filter, such as a low-pass filter, a high-pass filter, or a band-pass filter. The filter may have any convenient design, and the filter characteristics may vary depending on the characteristics of the signals that need to be distinguished.

[0168] In some aspects, the router may contain one or more controlled switches that route the signal to the appropriate functional blocks. The switches may include, but are not limited to, analog switches, a multiplexer, relays, etc., or any combination of these. The switches may be controlled by other circuitry which detects the signal present and routes it accordingly. Alternatively, the switches may be controlled by software. In other aspects, the switches may be controlled by the user. For example, there may be a user interface on the housing of the device or on an external controller. The user interface may include, but is not limited to one or more switches, one or more buttons, a touchscreen, etc. by which the user can select the appropriate operating mode and the router switches can be set accordingly. In some instances, the operating mode of the device can be modified by the internal circuitry or software based on the signal input from the multi-purpose connector. The potential operating modes may include, but are not limited to, patient interactive mode, power charging mode, data communication mode, etc. The switches may then be routed according to the operating mode.

[0169] In some instances where data or processing commands are to be sent through the multiple-purpose connector, it may be desirable to select a signaling protocol that is compatible with the patient connection circuitry. To comply with regulatory requirements, the patient electrical connections may have safety capacitors connected to the electrical connections to protect the patient from DC voltages. In these aspects, it may be desirable to select a communication protocol that does not rely on DC levels to represent the data bits, i.e., a 1 or a 0. Instead, a data communication protocol may be chosen that relies on transitions or frequency modulation to represent the data. In other instances, it may not be necessary to avoid a DC data protocol, and any convenient data protocol may be used. [0170] A block diagram of a receiver comprising a multi-purpose connector is shown in FIG. 16, where the device is shown in patient interactive mode. Receiver 1601 is connected to patient 1603 through multi-purpose connector 1605. Multi-purpose connector 1605 is located on housing 1607 and is connected to router 1609. Router 1609 connects to internal power source 161 1 , signal acquisition block 1613, energy output block 1615, and/or controller and data input/output block 1617. As shown, the receiver 1601 is connected to a patient 1603, and thus the router 1609 passes a signal to signal acquisition block 1613 via connection 1619. Energy can be delivered to the patient by energy output block 1615 through connection 1621. Connection 1621 may or may not share the same electrical lines as connection 1619.

[0171] The same receiver is shown in FIG. 17, where the device is shown in power charging mode. External power source 1723 is connected to receiver 1701 through multi-purpose connector 1705. Multi-purpose connector 1705 is connected to router 1709. Router 1709 recognizes that the incoming signal is a power charging signal, and accordingly routes the signal to internal power source 171 1 through connection 1725, thus charging internal power source 171 1 .

[0172] FIG. 18 shows receiver 1801 when the device is in data communication mode. External control and data communication device 1827 is connected to receiver 1801 through multi-purpose connector 1805. Multi-purpose connector 1805 is connected to router 1809. Router 1809 recognizes the incoming signal as a control and/or data communication signal, and accordingly routes the signal to control and data input/output block 1817 along connection 1829. External control and data communication device 1827 may then send a control signal and/or data packet to control and data input/output block 1817 or send a signal requesting data from control and data input/output block 1817. Control and data input/output block 1819 may send data to external control and data communication device 1827 over the same connection 1829, or over a different connection, including a wireless connection.

[0173] An example of a router which can be employed in receivers of the invention is shown in FIGS. 19A and 19B. FIG. 19A depicts a router that discriminates the signal based on voltage level. Only signals that exceed the threshold voltage of router 1931 will be passed from bus 1933 to bus 1935. A simple example of this principle is shown in FIG. 19B, in which diode 1937 acts as the signal director, e.g., router 1909. Only signals which are greater than the threshold voltage of diode 1937 will be passed from bus 1939 to bus 1941.

[0174] FIGS. 2OA and 2OB show examples of routers that discriminate based on the frequency of the incoming signal. FIG. 2OA shows the principle of a router based on frequency with incoming signal bus 2043 and functional block busses 2045 and 2047. Element 2049 has an impedance which increases with frequency, and forms a high pass filter with resistor 2050. Only signals above the design frequency of the high- pass filter will be passed from bus 2043 to bus 2045. Element 2051 has an impedance which reduces with frequency, and forms a low pass filter with resistor 2052. Only signals below the design frequency of the low- pass filter will be passed from bus 2043 to bus 2047. The high-pass filter and low-pass filter may or may not have different design frequencies. FIG. 2OB shows a simple example of this principle. Capacitor 2053 and resistor

2054 form a high-pass filter between bus 2057 and bus 2059, and inductor

2055 and resistor 2056 form a low-pass filter between bus 2057 and bus 2061 . Only those signals above the cutoff frequency are allowed to pass from bus 2057 to bus 2059, while only those signals below the cutoff frequency are allowed to pass from bus 2057 to bus 2061 .

[0175] FIG. 2OC shows another example of a router that discriminates based on the frequency of the incoming signal. High-pass filter 2056 has a gain that drops off below a certain design frequency. Only signals above the design frequency will pass from bus 2058 to bus 2060. Low-pass filter 2062 has a gain that drops off above a second design frequency. Only signals above the design frequency will pass from bus 2058 to bus 2064.

[0176] FIG. 21 shows an aspect of the router that employs active switches. Bus 2163 is separated from busses 2165, 2167, and 2169 by switches 2171 , 2173, and 2175. Busses 2165, 2167, and 2169 each connect to one or more functional blocks of the external receiver. Switches 2171 , 2173, and 2175 may be controlled by other circuitry, software, and/or by the user to open or close as needed to connect or disconnect bus 2163 to the corresponding functional block.

[0177] Receivers of the invention may incorporate circuitry connected to a multi-purpose connector which inherently routes an applied AC voltage, which is above a certain threshold, to a rectifying means, a power conversion means, and then to a battery charger circuit which uses the energy to charge the internal battery. The data acquisition circuitry inside the receiver is immune to the specified applied AC voltage. The receiver also detects the presence of this voltage and can change its operating mode based on that information.

[0178] FIGS. 22-24 show one example of circuitry for an aspect of the receiver. FIG. 22 shows the multi-purpose electrode connections SNAP_E1 2277, SNAP_E2 2279, and SNAP_E3 2281 , along with switches 221 13, 221 15, and 221 17 which connect the electrodes to the signal reception block through signal reception amplifier inputs 22121 and 22123. Diodes 2283, 2285, and 2287 protect the circuitry from damage due to electrostatic discharge (ESD). Inductors 2289, 2291 , and 2293 reduce electromagnetic interference (EMI). Capacitors 2295, 2297, and 2299 protect the patient by preventing any DC voltage from being applied to electrodes 2277, 2279, and 2281. Lines ChargelnACI 22101 , ChargelnAC2 22103, and ChargelnAC3 22105 connect the inputs to the internal power source which is shown in a subsequent figure. Capacitors 22107, 22109, and 221 1 1 prevent any DC voltage from being applied to the signal reception amplifier. Switches 221 13, 221 15, 221 17, and 221 19 are used to select any combination of the three electrodes 2277, 2279, and 2281 to go to the two signal reception amplifier inputs V+diff 22121 and V-diff 22123.

[0179] In the device shown in FIG. 22, it is not possible to disconnect the signal reception block completely. If a power charging signal is applied to the electrodes, it will be passed through the switches and on to the amplifier inputs. However, the amplifier inputs are designed to be immune to the relatively large voltage, so disconnecting the signal reception block is unnecessary. [0180] In an alternative configuration, it may be possible to disconnect the signal reception block when a signal other than a data signal is received on the electrodes. This may be accomplished, for example, by using additional switches and/or a different arrangement of switches.

[0181] The battery charger inputs to the internal power source functional block are shown in FIG. 23. Lines ChargelnACI 22101 , ChargelnAC2 22103, and ChargelnAC3 22103 from FIG. 22 connect to the power source functional block at ChargelnACI 23125, ChargelnAC2 23127, and ChargelnAC3 23129, respectively. Diodes 23131 -23136 form a three- phase rectifier. When the device is connected to an external power charger, the rectifier takes the power charging signal, which may be an alternating current, e.g., a 100 kHz square wave, and converts it to a DC current on net Charger ln 23139. When the voltage present on the inputs is less than about 0.6 V, such as when the device is connected to a patient, the signal is not passed through the rectifier and Charger ln node 23139 is disconnected from inputs 23125, 23127, and 23129. This isolates the low impedance of Charger ln node 23139 from the electrodes when it is needed to make a high impedance measurement of the signal on the patient. Boost converter 23141 boosts the voltage on net Charger ln 23139 to the desired power charging voltage, e.g., about 5V. The boosted voltage is passed on to the battery charger through node 23143. Diode 23145 protects the circuit in case a higher than desired voltage is placed on Charger ln node 23139.

[0182] An aspect of the battery charger circuitry is shown in FIG. 24. Output node 23143 from FIG. 23 connects with the battery charger circuit in FIG. 24 at battery charger input node 24147. Battery charger input 24147 connects to battery charger integrated circuit 24149. In this aspect, battery charger input 24147 is configured to recharge a battery, e.g., a lithium battery, at battery pads 24151 and 24153. The rest of the circuitry shown in FIG. 24 includes regulators 24155, 24157 and 24159 which condition the battery voltage for use in the rest of the circuitry in the device.

[0183] During use, the receiver may be operatively coupled to either a living subject, such as a patient, or another external device via the multi- purpose connector. Other external devices which may be connected include, but are not limited to, an external power charger device, an external programming device, an external data processing device. The receiver may also be operatively coupled to another medical device via the multi-purpose connector, including to the external proximal end of an implanted medical device. When the patient or another device is connected to the external medical device via the multi-purpose connector, when present the router may open and close signal pathways based on the type of signal or characteristics of the signal. As discussed above, the routing may be done inherently, actively, or by a combination of these and other techniques.

[0184] FIG. 25 provides a schematic of component/functionality relationships that may be achieved in aspects that have multi-purpose connectors. The schematic, for example, provides for a signal director 2500. The signal director 2500 comprises a control element 2502. The control element 2502 may control, or be responsive to, voltage 2504, frequency 2506, manual/ programmatic commands 2508, and other criteria 2510. The voltage 2504 may be discriminated via one or more diodes 2512, a thermistor 2514, etc. The frequency 2506 may be discriminated by a high-pass filter 2516, a low-pass filter 2518, etc. Signals may be manually and/or programmatically controlled by manual / programmatic commands 2508 via analog switches 2520, a relay 2522, a multiplexor 2524, etc. Other criteria 2510 for signal control/response may include, for example, light, temperature, time, etc.

[0185] Methods of using devices with multi-purpose connectors of the invention also include disconnecting the receiver from either the patient or one of the other devices discussed above, and operatively coupling the device to another one of either the patient or one of the other devices via the multi-purpose connector. When present, the router in the receiver may route the signal from the second connected device differently than the signal from the first connected device. In addition, the operating mode of the external medical device may change in response to the signal from the second connected device. [0186] Further details regarding receivers that may include multi-purpose connectors of the invention and methods of their use may be found in United States Provisional Patent Application Serial No. 61/122,723 filed on December 15, 2008; the disclosure of which is herein incorporated by reference.

Impedance (EZ) Measurement Module

[0187] Receivers of the invention may include an impedance measurement module, for example where the devices are configured to measure impedance across at least a pair of electrodes of the device. Impedance measurement modules may be configured to determine the loop impedance of the series combination of two electrodes and a resistive load (for example as provided by intervening tissue). The impedance measurement module comprises a current source block to provide current across the electrodes, and a voltage processing block to measure the voltage signal across the resistive load and to determine the electrode impedance. For example, the receiver may be configured to apply a 2 μApp (RMS amplitude is 1 μArms) square wave current across its two electrodes. This is sufficient to detect a detached electrode. Applications may include, but are not limited to receiver diagnostic applications, e.g., where measured impedance is employed to determine if an electrode is disconnected from the patient and/or is not working, patient monitoring applications, such as where impedance is employed to determine one or more physiological parameters, etc.

[0188] FIG. 27 provides a circuit diagram modeling a drive scheme 2700 implemented by the current source block, according to one aspect of the invention. As shown in this aspect, a bipolar current may be derived from a unipolar logic drive, with no "DC" component in the drive scheme. Two currents, "EZ_Carrier" 2720 and "EZ_Balance" 2730, are generated and provide an electrode current lez 2710 across the two electrodes. "EZ_Carrier" 2720 and "EZ_Balance" 2730 may, for example, be generated by the low power processor (e.g., microprocessor), and implemented together in series with capacitor 2740 and resistor 2750 (the unknown electrode impedance).

[0189] The voltage processing block measures a voltage signal 2760 across the electrodes (i.e., across the resistive load — resistor 2710) resulting from electrode current lez 2710. The voltage processing block may then use voltage signal 2710 to determine the electrode impedance. For example, voltage signal 2710 may first be amplified by [Gain=287], band-limited by a 5 KHz HPF and 33 KHZ LPF to reduce noise, and applied to an A/D converter input (e.g., a 12-bit A/D converter sampling at 500 KHz) to provide a digital data stream from the voltage signal. A DSP, for example, may process the digital data stream to determine the electrode impedance. For example, the DSP may mix the input data stream with a sine wave at an EZ Carrier frequency (e.g., 20KHz), apply a Hogenauer ("CIC") filter to low-pass filter, and decimate (e.g., by 16) the data stream. This moves the fundamental of the carrier energy to OHz. The DSP may then calculate the absolute value (magnitude) of the data stream, average that over a 1 second period, and convert to impedance using the formula:

Zelectrode = ( Vc / ( lez ^* Gain ) ) -300

[0190] where: Vc is the measured amplitude at the A/D converter, at the lez carrier frequency (20KHz). Gain setting G3...G0 = 0000; using 287 as the Gain value for calculation. This results in a 300 ohm Tare resistance (electrode impedance) in series with the electrode being measured.

[0191] FIG. 28 provides for a circuit diagram for an electrode impedance measurement using a 3-wire ohmmeter, according to one aspect of the invention. Current source block generates EZ carrier line 2820 and EZ Balance line 2830 to provide electrode current (lez) 2810 flowing through resistive load, electrode resistance En 2850. With a Kelvin connection, and no current flowing through electrode (impedance) Em 2860, the voltage observed by the first stage 2870 will be lez ^* (300 +En). Electrode current lez 2810 may be, for example, 2 μApp = 1 μARMS.

[0192] An impedance measurement module includes control module and processing module and electrodes. Impedance measurement is an example of a sensing capability that may be accomplished with any two electrodes of a receiver. In addition to determining functionality of the device and placement thereof, e.g., whether the electrodes are working and/or connected to the subject as desired, physiological data of interest may be derived from the measured impedance. For example, the measured impedance will have some component which is determined by the trans-thoracic impedance, which relates to respiration. In this manner, the impedance data can be employed to obtain the respiratory rate of the subject. The electrodes 2860may also be employed as sensors of the fluid state of subject. Over time, particularly for a heart failure patient on diuretics, fluid status is a very important quantity. The obtained fluid state can be used to titrate medications and/or provide alerts. In addition to measuring fluid status, impedance measurements could also be used to measure body fat.

MODULE IMPLEMENTATION

[0193] In various aspects, the above described modules, e.g., high power- low power modules, intermediary modules, the transbody conductive communication module, the physiological sensing modules, power supply modules, storage modules, extra-corporeal communications modules, etc., and/or one or a combination of their components, may be implemented as software, e.g., digital signal processing software; hardware, e.g., a circuit; or combinations thereof. As such, additional elements that may be present in the signal receiver include, but are not limited to: a signal demodulator, e.g., for decoding the signal emitted from an IEM; a signal transmitter, e.g., for sending a signal from the signal receiver to an external location; a data storage element, e.g., for storing data regarding a received signal, physiological parameter data, medical record data, etc.; a clock element, e.g., for associating a specific time with an event, such as receipt of a signal; a pre-amplifier; a microprocessor, e.g., for coordinating one or more of the different functionalities of the signal receiver, bandpass filters, etc. [0194] In certain aspects, the modules of the present receivers are present on integrated circuits, where the integrated circuits include a number of distinct functional blocks. Within a given receiver, at least some of, e.g., two or more, up to an including all of, the modules may be present in a single integrated circuit in the receiver (for example, in the form of a system on chip or SOC). By single integrated circuit is meant a single circuit structure that includes all of the different functional blocks. As such, the integrated circuit is a monolithic integrated circuit (also known as IC, microcircuit, microchip, silicon chip, computer chip or chip) that is a miniaturized electronic circuit (which may include semiconductor devices, as well as passive components) that has been manufactured in the surface of a thin substrate of semiconductor material. The integrated circuits of certain aspects of the present invention may be hybrid integrated circuits, which are miniaturized electronic circuits constructed of individual semiconductor devices, as well as passive components, bonded to a substrate or circuit board.

[0195] FIG. 7 provides a block functional diagram of an integrated circuit component of a signal receiver according to an aspect of the invention. In FIG. 7, receiver 700 includes electrode input 710. Electrically coupled to the electrode input 710 are transbody conductive communication module 720 and physiological sensing module 730. In one aspect, transbody conductive communication module 720 is implemented as a high frequency (HF) signal chain and physiological sensing module 730 is implemented as a low frequency (LF) signal chain. Also shown are CMOS temperature sensing module 740 (for detecting ambient temperature) and a 3-axis accelerometer 750. Receiver 700 also includes a processing engine 760 (for example, a microcontroller and digital signal processor), non-volatile memory 770 (for data storage) and wireless communication module 780 (for data transmission to another device, for example in a data upload action).

[0196] FIG. 8 provides a more detailed block diagram of a circuit configured to implement the block functional diagram of the receiver depicted in FIG. 7, according to one aspect of the invention. In FIG. 8, receiver 800 includes electrodes e1 , e2 and e3 (81 1 , 812 and 813) which, for example, receive the conductively transmitted signals by an IEM and/or sense physiological parameters or biomarkers of interest. The signals received by the electrodes 81 1 , 812, and 813 are multiplexed by multiplexer 820 which is electrically coupled to the electrodes.

[0197] Multiplexer 820 is electrically coupled to both high band pass filter 830 and low band pass filter 840. The high and low frequency signal chains provide for programmable gain to cover the desired level or range. In this specific aspect, high band pass filter 830 passes frequencies in the 10 KHz to 34 KHz band while filtering out noise from out-of-band frequencies. This high frequency band may vary, and may include, for example, a range of 3 KHz to 300 KHz. The passing frequencies are then amplified by amplifier 832 before being converted into a digital signal by converter 834 for input into high power processor 880 (shown as a DSP) which is electrically coupled to the high frequency signal chain.

[0198] Low band pass filter 840 is shown passing lower frequencies in the range of 0.5 Hz to 150 Hz while filtering out out-of-band frequencies. The frequency band may vary, and may include, for example, frequencies less than 300 Hz, such as less than 200 Hz, including less than 150 Hz. The passing frequency signals are amplified by amplifier 842. Also shown is accelerometer 850 electrically coupled to second multiplexer 860. Multiplexer 860 multiplexes the signals from the accelerometer with the amplified signals from amplifier 842. The multiplexed signals are then converted to digital signals by converter 864 which is also electrically coupled to low power processor 870.

[0199] In one aspect, a digital accelerometer (such as one manufactured by Analog Devices), may be implemented in place of accelerometer 850. Various advantages may be achieved by using a digital accelerometer. For example, because the signals the digital accelerometer would produce signals already in digital format, the digital accelerometer could bypass converter 864 and electrically couple to the low power microcontroller 870 — in which case multiplexer 860 would no longer be required. Also, the digital signal may be configured to turn itself on when detecting motion, further conserving power. In addition, continuous step counting may be implemented. The digital accelerometer may include a FIFO buffer to help control the flow of data sent to the low power processor 870. For instance, data may be buffered in the FIFO until full, at which time the processor may be triggered to turn awaken from an idle state and receive the data.

[0200] Low power processor 870 may be, for example, an MSP430 microcontroller from Texas Instruments. Low power processor 870 of receiver 800 maintains the idle state, which as stated earlier, requires minimal current draw — e.g., 10μA or less, or 1 μA or less.

[0201] High power processor 880 may be, for example, a VC5509 digital signal process from Texas Instruments. The high power processor 880 performs the signal processing actions during the active state. These actions, as stated earlier, require larger amounts of current than the idle state — e.g., currents of 30 μA or more, such as 50 μA or more — and may include, for example, actions such as scanning for conductively transmitted signals, processing conductively transmitted signals when received, obtaining and/or processing physiological data, etc.

[0202] The receiver may include a hardware accelerator module to process data signals. The hardware accelerator module may be implemented instead of, for example, a DSP. Being a more specialized computation unit, it performs aspects of the signal processing algorithm with fewer transistors (less cost and power) compared to the more general purpose DSP. The blocks of hardware may be used to "accelerate" the performance of important specific function(s). Some architectures for hardware accelerators may be "programmable" via microcode or VLIW assembly. In the course of use, their functions may be accessed by calls to function libraries.

[0203] The hardware accelerator (HWA) module comprises an HWA input block to receive an input signal that is to be processed and instructions for processing the input signal; and, an HWA processing block to process the input signal according to the received instructions and to generate a resulting output signal. The resulting output signal may be transmitted as needed by an HWA output block.

[0204] FIG. 30 provides for a block diagram of a HWA module, according to one aspect of the invention. As shown, input block 3001 is coupled to processing block 3002 which is coupled to output block 3003. Input block 3001 receives input signal 3001 and/or instructions 3015. HWA module 300 may, for example, receive a transbody conductive communication signal from the transbody conductive communication module; and/or, receive physiological data signals from one or more physiological sensing modules.

[0205] The HWA module may receive an analog signal and include an A/D converter to convert the signal to a digital signal, or may receive a digital input signal (e.g., from an A/D converter or microprocessor). For example, the HWA module may be electrically coupled to an A/D converter and a microprocessor, having a state machine collecting data directly from the A/D converter. In another example, the hardware accelerator may be only connected to the microprocessor processing data as directed by the microprocessor.

[0206] Instructions 3015 may be, for example, received from an internal memory, external memory, or by a microprocessor. In one aspect, the HWA module shares memory with the microprocessor (e.g., via dual port memory or via a mux). In another aspect, the HWA module exchanges data via a DMA port.

[0207] The HWA processing block 3002 processes input signal 3010 according to received instructions 3015. Functions such as a DCO (digital controlled oscillator), DDC (digital down converter), FIR filter, CIC decimation may be implemented by such a hardware accelerator. These functions are optimal for IEM-related signal processing, and are also applicable to general purpose data acquisition, impedance measurement, ECG signal processing (Hamilton and Tomkins), accelerometer, etc. The resulting output signal 3020 that is generated by HWA processing block

3002 may be transmitted as needed by a HWA output block 3003. [0208] The HWA module 3000 may further comprise an HWA power block

3030 to enable/disable power to HWA module 3000. For example, HWA module 3000 may be configured to be powered off and on, or configured to be disabled by gating the clock which drives it, etc. The transistor count required to implement it is relatively small (roughly in the 10k to 100k gate range) with most of the static power drawn by the associated memory/buffers. The hardware accelerator is thus capable of low power consumption.

[0209] Also shown in FIG. 8 is flash memory 890 electrically coupled to high power processor 880. In one aspect, flash memory 890 may be electrically coupled to low power processor 870, which may provide for better power efficiency.

[0210] Wireless communication element 895 is shown electrically coupled to high power processor 880 and may include, for example, a BLUETOOTH™ wireless communication transceiver. In one aspect, wireless communication element 895 is electrically coupled to high power processor 880. In another aspect, wireless communication element 895 is electrically coupled to high power processor 880 and low power processor 870. Furthermore, wireless communication element 895 may be implemented to have its own power supply so that it may be turned on and off independently from other components of the receiver — e.g., by a microprocessor.

[0211] FIG. 9 provides a view of a block diagram of hardware in a receiver according to an aspect of the invention related to the high frequency signal chain. In FIG. 9, receiver 900 includes receiver probes (for example in the form of electrodes 91 1 , 912 and 913) electrically coupled to multiplexer 920. Also shown are high pass filter 930 and low pass filter 940 to provide for a band pass filter which eliminates any out-of-band frequencies. In the aspect shown, a band pass of 10 KHz to 34 KHz is provided to pass carrier signals falling within the frequency band. Example carrier frequencies may include, but are not limited to, 12.5 KHz and 20 KHz. One or more carriers may be present. In addition, receiver 900 includes analog to digital converter 950 — for example, sampling at 500 KHz. The digital signal can thereafter be processed by the DSP. Shown in this aspect is DMA to DSP unit 960 which sends the digital signal to dedicated memory for the DSP. The direct memory access provides the benefit of allowing the rest of the DSP to remain in a low power mode.

Example configurations for various states [0212] As stated earlier, for each receiver state, the high power functional block may be cycled between active and inactive states accordingly. Also, for each receiver state, various receiver elements (such as circuit blocks, power domains within processor, etc.) of a receiver may be configured to independently cycle from on and off by the power supply module. Therefore, the receiver may have different configurations for each state to achieve power efficiency. For instance, FIG. 29 shows the receiver to have idle and active states — e.g., idle state 1 10, sniff state 130, demodulate and decode state 140, collect ECG and accelerometer state 120, and transmission state 160). It should be noted that as stated earlier, the beacon signal module may implement various types of sniff signals to achieve low power efficiency, thus the sniff state has been grouped as an inactive state for the following example.

[0213] With the states shown in FIG. 29 in mind, the following paragraphs provide example configurations of receiver components shown in FIG. 8 during various states of the receiver, according to one aspect of the invention. It should be understood that alternative configurations may be implemented depending on the desired application.

[0214] In the state 1 10 the receiver draws minimal current. Receiver 800 is configured such that low power processor 870 is in an inactive state (such as idle state) and high power processor 880 is in an inactive state (such as idle state), and circuit blocks related to peripheral circuitry and their power supplies required during various active states remain off (for example, wireless communication module 895 and the analog front end). For example, the low power processor may have a 32 KHz oscillator active and may consume a few μA current or less, including 0.5 μA or less. In the idle state, the low power processor 870 may, for example, wait for a signal to transfer to an active state. The signal might be external such as an interrupt or internally generated by one of the device's peripherals, such as a timer. During the high power processor's idle state, the high power processor may, for example, be running off a 32 KHz watch crystal. The high power processor may, for example, wait for a signal to transfer to active state. [0215] When the receiver is in the sniff state, low power processor 870 is in an idle state and high power processor 880 is in an idle state. In addition, the circuit blocks relating to the analog front end including A/D converter that is needed for the sniff function are on (in other words, the high frequency signal chain). As stated earlier, the beacon signal module may implement various types of sniff signals to achieve low power efficiency.

[0216] Upon detection of a transmitted signal, a higher power demodulate and decode state may be entered. When the receiver is in the demodulate and decode state, low power processor 870 is in an active state and high power processor 880 is in an active state. High power processor 880 may, for example, be running from a 12 MHz or near crystal oscillator with a PLL-based clock multiplier giving the device a 108 MHz clock speed. The low power processor 870 may, for example, run off an internal R-C oscillator in the range of 1 MHz to 20 MHz and consume power in the range of 250 to 300 uA per MHz clock speed during active states. The active state allows for processing and any transmissions that may follow. Required transmissions may trigger the wireless communication module to cycle from off to on.

[0217] When the receiver is in collect ECG and accelerometer state, the circuit blocks relating to the accelerometer and/or ECG signal conditioning chain are on. The high power processor 880 is in an in idle state during collection, and in an active state (for example, running from a 12 MHz or near crystal oscillator with a PLL-based clock multiplier giving the device a 108 MHz clock speed) during processing and transmission. The low power processor 870 is in an active state during this state and may run off an internal R-C oscillator in the range of 1 MHz to 20 MHz and consume power in the range of 250 to 300 uA per MHz clock speed.

Additional states for the receiver

[0218] In addition to the states of operation where the receiver cycles between idle and active states, the receiver may include other states of operation. Receivers may include a storage state, for example, exhibiting a very low current draw of 10 μA or less, such as 1 μA or less and including 0.1 μA or less. In the storage state the receiver may be configured, for example, so that the low power processor is in an idle state, the high power processor is off, and other receiver elements such as circuit blocks relating to peripheral circuitry needed during active states is off. FIG. 29 illustrates a storage state 170 for a receiver. The receiver may be transitioned from a storage state to a non-storage state according to a variety of inputs, such as a predetermined schedule or an applied stimulus, e.g., in response to a manual manipulation of the receiver (for example by pressing an "on" button or removing a tab from the receiver) or in response to an "on" signal transmitted to the receiver. As shown in FIG. 1 , the receiver may transition from storage state 170 into an idle state 1 10.

[0219] Receivers may also be configured to include a charging state, as shown in FIG. 29 as charging state 150. When the receiver is in the charging state, only the low power processor is on, for example in an idle state. The circuit blocks relating to the power supply of the high power processor and all peripherals are turned off.

[0220] Receivers may also be configured to include a transmission state 160, where data may be transmitted to and/or from the receiver and another extra-corporeal device, for example by using a wireless communication protocol. The high power processor is in an active state, the low power processor is in an active state, and other receiver elements such as circuit blocks related to the wireless communication module are on.

[0221] Receivers may also be configured to include a "diagnostics" state. In a diagnostics state, the receiver may test the operation of one or more functions of the receiver, e.g., signal receiving, physiological data obtainment and/or processing, etc., to determine whether the functions are being performed correctly. The receiver may further be configured to report to a user, e.g., via a signal (which may be audible, visual, relayed to a third device, etc.) the results of the test. For example, the receiver may be configured to report to a user that all functions are operating normally, or that there is a problem with one or more functions. In some aspects, the receiver transitions into and out of a diagnostics state according to different inputs, such as a predetermined schedule (for example as provided by receiver programming) or applied stimulus, such as described above.

Communication via Serial Peripheral Interface Bus

[0222] The low power processor (e.g., MSP shown in FIG. 8) and high power processor (e.g., DSP shown in FIG. 8) may communicate with each other using any convenient communication protocol. In some instances, these two elements, when present, communicate with each via a serial peripheral interface bus (hereinafter "SPI bus"). The following description describes the signaling and messaging scheme implemented to allow the high power processor and low power processor to communicate and send messages back and forth along the SPI bus. For the following description of the communication between the processors, "LPP" and "HPP" are used in place of "low power processor" and "high power processor", respectively, to stay consistent with FIG. 8. The discussion, however, may apply to other processors than those shown in FIG. 8. [0223] The interface is configured so the LPP is the master and the HPP is the slave, and the link is driven only by the LPP side. The HPP can only respond to the LPP via SPI. Furthermore, SPI requires that the HPP respond immediately to the LPP. If the LPP sends data and the HPP is not waiting for the data, then the data are lost. The signaling and messaging configuration for the interface is described below, according to one aspect of the invention, in order to overcome these limitations.

Signaling

[0224] To overcome the limits described above, three "out of band" signals are implemented in the signaling protocol. The LPP has an "Attention" signal that it can assert and de-assert, and the HPP has an "Attention" and a "Grant" signal. [0225] For the LPP to send data (e.g., LPP-initiated messages) to the HPP, the LPP asserts its LPP Attention signal. It then waits until the HPP responds by asserting the HPP Grant signal. This ensures that both sides are ready for the SPI transaction and no data are lost. At this point, the HPP is able to receive messages from the LPP. If currently unable to receive LPP-initiated messages from the LPP, the HPP is then enabled to receive LPP-initiated messages. The HPP remains "on the line" until the LPP de-asserts its LPP Attention signal. The HPP responds to this de- assert by de-asserting its HPP Grant signal. At this point, the HPP is unable to receive messages from the LPP. Since able to receive LPP- initiated messages from the LPP, the HPP is then disabled from receiving LPP-initiated messages). In this case, the system responds to both the change in level of the signals and the levels themselves. In other words, the system sees the signal asserted as a request for action and the system looks at the level of that signal as an indicator of continuing action. Because the HPP does not need to do anything until the LPP asserts its LPP Attention signal, the HPP may enter into a low power idle state. In such case, the LPP Attention signal not only requests the SPI link but also wakes up the HPP.

[0226] For the HPP to send data (e.g., HPP-initiated messages) to the LPP, the HPP asserts its HPP Attention signal. The assert notifies the LPP that the HPP has data. The assert of the HPP Attention signal is what alerts the LPP, not the de-assert of the HPP Attention signal. The HPP need only de-assert this signal before it can assert it again. Once the LPP sees the HPP Attention signal asserted, it will eventually respond by following 1 ) above. There is no requirement that the LPP respond immediately. In this case, it is only the assertion of the signal that matters. The system never looks at the ongoing level of that signal.

Messaging:

[0227] Because of the master/slave designation of the SPI bus, the HPP can only respond to a LPP message. It cannot ask a question of the LPP. In order to enable data flow in both directions, the above signaling is implemented in combination with two types of messaging, as described below.

[0228] For LPP-initiated messages to the HPP, case 1 ) above may be employed to send messages to the HPP. This class of messages never requires a response message from the HPP. One example message may be the command, "Process this ECG". A message tells the HPP to expect ECG data and then the LPP sends a series of messages containing the ECG data to the HPP. Another example may be when the LPP sends a command to the HPP telling it to go sniff for transmitted IEM signals.

[0229] For HPP-initiated messaging, the messages must still originate at the LPP. To accomplish this direction of communication, case 2) above is used to tell the LPP to query the HPP for a message. Before the HPP asserts the HPP attention signal, it prepares the query information (i.e., the HPP-initiated message) so that it can immediately respond to the LPP. The LPP sends a series of messages to get the query from the HPP. The LPP asks for the query length, and does so by sending a "query length" message to the HPP. The LPP then uses that length to request the HPP- initiated message. Because the LPP asks for the query length, the LPP knows exactly how much data to pull from the HPP. The LPP answers the HPP's "question" by sending a query response message to the HPP. With the HPP implemented to have only one outstanding query at a time, it knows to expect this response.

[0230] It should also be pointed out that for the above sequence, the LPP always knows exactly how much data to pull from the HPP because it "clocks" the SPI link. Furthermore, in this aspect, because the LPP always asks the questions and the HPP is always ready to respond to any question from the LPP, the HPP is not guaranteed to always get the "query length" message from the LPP when it wants to send a query.

[0231] In one aspect, error detection and correction may be implemented, e.g., by using a Fletcher checksum algorithm. Because a retry is executed upon error detection, for any messages that require an action to be taken (such as pill sniff, etc.), that action is not taken until the entire case 1 ) above is complete. This is important because the LPP may detect an error while the HPP saw correct data. It is the completion of case 1 ) above that is the final acknowledgement of complete and correct data transmission.

Global Positioning System (GPS) Module

[0232] Receivers of the invention may include a Global Positioning System

(GPS) module. GPS modules as used herein are modules that receive signals from the Global Positioning System of satellites and determine geographical location. Any convenient GPS module may be employed.

RECEIVER CONFIGURATIONS

[0233] Body-associate medical devices of interest include both external and implantable devices. In external aspects, the receiver is ex vivo, by which is meant that the device is present outside of the body during use. Where the receivers are external, they may be configured in any convenient manner, where in certain aspects they are configured to be associated with a desirable skin location. As such, in certain aspects the external receivers are configured to be contacted with a topical skin location of a subject. Configurations of interest include, but are not limited to: patches, wrist bands, jewelry (such as watches, earrings and bracelets), clothing, accessories, e.g., belts and shoes, eyeglasses, etc. In some instances, the receivers are configured to adhere to a skin location, e.g., by use of suitable adhesive, such as described below. In some instances, the receivers are configured to touch a skin location but not adhere thereto, for example where the device is configured as a wrist band, an item of jewelry (such as a watch, an earring and a bracelet), an article of clothing, an accessory, such as a belt and a shoe, and a pair of eyeglasses. In yet other instances, the receivers may be configured to be maintained within some defined distance of a skin surface, such as within 1 cm, including within 0.5 cm.

[0234] In certain aspects, the receiver is an implantable component. By implantable is meant that the receiver is designed, i.e., configured, for implantation into a subject, e.g., on a semi-permanent or permanent basis. In these aspects, the receiver is in vivo during use. By implantable is meant that the receivers are configured to maintain functionality when present in a physiological environment, including a high salt, high humidity environment found inside of a body, for two or more days, such as about one week or longer, about four weeks or longer, about six months or longer, about one year or longer, e.g., about five years or longer. In certain aspects, the implantable receivers are configured to maintain functionality when implanted at a physiological site for a period ranging from about one to about eighty years or longer, such as from about five to about seventy years or longer, and including for a period ranging from about ten to about fifty years or longer. For implantable aspects, the receiver may have any convenient shape, including but not limited to: capsule-shaped, disc-shaped, etc. The receiver may be configured to be placed in a number of different locations, e.g., the abdomen, small of the back, shoulder (e.g., where implantable pulse generators are placed) etc. In certain implantable aspects, the receiver is a standalone device, in that it is not physically connected to any other type of implantable device. In yet other aspects, the receiver may be physically coupled to a second implantable device, e.g., a device which serves as a platform for one or more physiological sensors, where the device may be a lead, such as a cardiovascular lead, where in certain of these aspects the cardiovascular lead includes one or more distinct physiological sensors, e.g., where the lead is a multi-sensor lead (MSL). Implantable devices of interest further include, but are not limited to: implantable pulse generators (e.g., ICDs), neurostimulator devices, implantable loop recorders, etc. 35] Receivers may include a signal receiver element which serves to receive the conductively transmitted signal, such as a signal emitted by an identifier of an ingestible event marker. The signal receiver may include a variety of different types of signal receiver elements, where the nature of the receiver element necessarily varies depending on the nature of the signal produced by the signal generation element. In certain aspects, the signal receiver element may include one or more electrodes for detecting signal emitted by the signal generation element, such as two or more electrodes, three or more electrodes, etc. In certain aspects, the receiver device will be provided with two or three electrodes that are dispersed at some distance from each other. This distance allows the electrodes to detect a differential voltage. The distance may vary, and in certain aspects ranges from 0.1 cm to 1 .0 m, such as 0.1 to 5 cm, such as 0.5 to 2.5 cm, where the distance 1 cm in some instances.

[0236] An example of an external signal receiver aspect of a receiver of interest is shown in FIG. 10. FIG. 10 shows receiver 1000 that is configured to be placed on an external topical location of a subject, such as a chest area. The receiver includes an upper housing plate 1010 (such as may be fabricated from a suitable polymeric material), and includes a manually depressible operation button 1020 and a status identifier LED 1030, which may be used to relay to an observer that the receiver is operating. Manually depressible operation button 1020 can be manually manipulated to transition the receiver from a storage mode to a non- storage mode. When the receiver is in the storage mode, a microcontroller of the receiver may remain in a low duty cycle active state at all times to process input from the on/off button, and the digital signal processor (DSP) of the receiver powered off. When the on/off button is depressed to turn on the receiver, the micro-controller de-bounces the input and powers the DSP into its idle state. While in storage mode, the device may draw less than 10 μA, including 5 μA of current or less, such as 1 μA or less and including 0.1 μA or less.. This configuration enables the device to remain at greater than 90% useful battery life if stored for one month (assuming the presence of a 250 mAH battery). Such a button may also be employed for other functions. For example, such a button may be employed to instruct the receiver to obtain certain types of data. In addition or alternatively, such a button may be employed to manually instruct the receiver to transfer data to another device.

[0237] FIG. 1 1 provides an exploded view of the receiver shown in FIG. 10. As shown in FIG. 1 1 , receiver 1000 includes upper housing plate 1010, rechargeable battery 1 100, integrated circuit component 1 120, and bottom housing plate 1 130. Bottom housing plate 1 130 snap fits into top housing plate 1010 to seal the battery and integrated circuit components, 1 100 and 1 120, in a fluid tight housing. While a snap-fit interaction is illustrated, any convenient mating scheme may be employed, such that the top and bottom housing plates may interact via inter-locking grooves, may be held together via a suitable adhesive, may be welded together, etc. In some instances, the electrical components may be molded into the top and/or bottom housing plates. Also shown is adhesive patch 1 140 which snaps into top housing plate 1010 and includes conductive studs 1 141 to 1 143, which studs serve as electrode contacts with the body during receiver use. In the receiver, studs 1 141 to 1 143 are in electrical contact with integrated circuit component 1 120, e.g. via wires or other conductive members associated with the upper housing 1010. In one instance, upper housing plate 1010 includes conductive members configured to receive studs 1 141 to 1 143 coupled to wires (not shown) which in turn provide electrical connection to the integrated circuit component 1 120. 38] FIG. 12 provides an exploded view of adhesive patch 1 140. Adhesive patch 1 140 includes upper studs 1 141 , 1 142 and 1 143, as described above. These studs are in electrical contact with skin contact studs 1 151 , 1 152 and 1 153. On the skin side surface of skin contact studs 1 151 , 1 152 and 1 153 is a conductive hydrogel layer 1 154. Around each stud 1 151 , 1 152 and 1 153 are non-conductive hydrogel 1 155 and pressure sensitive adhesive 1 156 components. In this portion, any convenient physiologically acceptable adhesive may be employed. In some instances, adhesive that chance their adhesive properties in response to an applied stimulus are employed. For example, adhesives that become less adhesive upon application of light, e.g., UV light, or a chemical, may be employed, so that the adhesive remains strong while it is desired for the receiver to remain associated with the body but is readily weakened to facilitate removal of the receiver from the body when desired. On the non-skin side of each skin contact stud is a layer of dry electrode material, such as Ag/AgCI. On the upper surface of this layer of dry electrode material is a porous layer, such as a carbon vinyl layer. Also shown are upper backing layers 1 180. Though not shown, upper studs 1 141 to 1 143 are in electrical contact through the backing layers 1 180 (for example urethane and polyethylene) with the dry electrode and skin contact studs which are positioned beneath each upper stud. As illustrated, the studs are off center with respect to their dry electrode layer in the direction of the outer edge of the patch in a manner sufficient to increase dipole size between any two given studs. In addition, where desired a conductivity gradient may be associated with each stud, e.g., by altering the pattern of the porous layer 1 170 and/or modifying the composition of the dry electrode layer. Of interest in such aspects is where a conductivity gradient increases in conductivity in the direction of the outer edge of the patch.

[0239] FIGS. 13A to 13E provide various views of an alternative external patch configuration 1300 which includes two electrodes 1310 and 1320 in a flexible structure having an adhesive bandage configuration. Patch 1300 includes upper flexible outer support 1330 and bottom flexible support 1350 which fit together as shown in FIG. 13E to enclose an integrated circuit/battery component 1360 and electrodes 1310 and 1320. As shown in FIG. 13D, the bottom surfaces of electrodes 1310 and 1320 are exposed. As shown in FIG. 13E, electrodes 1310 and 1320 include lead elements 1375 and 1370 which provide for electrical contact between the electrodes and the integrated circuit/battery component 1360. Any convenient adhesive component may be employed, such as those described above.

[0240] FIGS. 14A to 14B provide block diagrams of example hardware configurations that may be present in a receiver as shown in FIGS. 13A to 13E. However, it should be understood that the example hardware configurations are not limited to the aspects shown in FIGS. 13A to 13E.

[0241] FIG. 14A provides a block diagram of an example hardware configuration that may be included in a receiver such as receiver 1300, according to one aspect of the invention. As shown, hardware system 1400 includes first and second electrodes 1310 and 1320 electrically coupled to analog ASIC 1410. ASIC 1410 may include, for example, the analog front end of hardware system 1400 (e.g., the high frequency signal chain, low frequency signal chain, etc.). Just as the analog front end may be implemented in an ASIC, customized logic may replace the DSP. Digital ASIC 1420 is shown electrically coupled to analog ASIC 1410 and performs the digital signal conditioning and processing. Accelerometer 1430, such as a three-axis accelerometer, is shown electrically coupled to digital ASIC 1420. In one aspect, accelerometer 1430 is electrically coupled to analog ASIC 1410. It is also understood that a digital accelerometer may be implemented. Microprocessor 1440 is shown electrically coupled to digital ASIC 1410 and flash memory 1450. Furthermore, microprocessor 1440 is shown electrically coupled to radio 1460, such as a wireless transceiver.

[0242] FIG. 14B provides a block diagram of another example hardware configuration that may be included in a receiver such as receiver 1300, according to one aspect of the invention. Within hardware system 1490, electrodes 1310 and 1320 are shown electrically coupled to optional low noise amplifier (LNA) 1461. Analog ASIC 1462 is shown electrically coupled to LNA 1461 and may include, for example, the analog front end of hardware system 1490. Digital ASIC 1463 is shown electrically coupled to analog ASIC 1462 and performs the digital signal conditioning and processing. In this aspect, digital ASIC 1463 also includes microprocessing unit 1464, which may be any convenient microprocessing unit such as the CORTEX-M3™ microprocessing unit by ARM. Accelerometer 1430 is electrically coupled to analog ASIC 1462, but as noted earlier, may be implemented to be electrically coupled to the digital ASIC 1463 as well as a digital accelerometer. Electrically coupled to digital ASIC 1463 is radio 1460.

[0243] FIG. 14C provides a block diagram of yet another example hardware configuration that may be included in a receiver such as receiver 1300, according to one aspect of the invention. Within hardware system 1480, a single system on chip (SOC) 1470 replaces the two ASICs in FIG. 14A and 14B. For instance, SOC 1470 would replace ASICs 1410 and 1420 shown in FIG. 14A, or ASICs 1462 and 1463 shown in FIG. 14B (in which case optional LNA 1460 is not shown). In this case, radio 1460 is electrically coupled to SOC 1470. [0244] FIG. 14D provides a block diagram of yet another example hardware configuration that may be included in a receiver, such as receiver 1300, according to one aspect of the invention. Within hardware system 1499, optional LNA 1461 is electrically coupled to electrodes 1310 and 1320. SOC 1482 is shown electrically coupled to an optional LNA 1461 , accelerometer 1430, temperature sensor 1494 and radio 1498 (e.g., a wireless communication module including a transceiver). SOC 1492 includes processor 1492, electrode input 1484, analog front end 1486 (e.g., transbody conductive communication module and physiological sensing modules), and software defined radio 1488. Furthermore, a temperature sensor 1496 may also be included in single ASIC 1470 and/or radio 1498 (sensor not shown).

[0245] Where desired, one or more components of the receiver may be covered with a conformal, void-free sealing layer, e.g., as described in United States Application Serial No. 12/296,654, the disclosure of which application is herein incorporated by reference. The conformal, void-free sealing layer may be characterized as a "thin-film" coating in that its thickness is such that it does not substantially increase the total volume of the structure with which it is associated, where any increase in volume of the device that can be attributed to the layer is about 10% or less, such as about 5% or less, including about 1 % or less by volume. According to aspects of the invention, a conformal, void-free sealing layer has a thickness in a range from 0.1 to 10.0 μm, such as in a range from 0.3 to 3.0 μm, and including in a range from 1 .0 to 2.0 μm thick. According to aspects of the present invention, a conformal, void-free sealing layer may be applied using a planar processing protocol, e.g., plasma-enhanced- chemical-vapor deposition, physical-vapor deposition, sputtering, evaporation, cathodic-arc deposition (see e.g., United States Application Serial No. 12/305,894, the disclosure of which application is herein incorporated by reference), low-pressure chemical-vapor deposition, and other such processes. When present, conformal, void-free sealing layers may comprise a variety of different materials. In one aspect, the layer comprises silicon carbide to create a highly corrosion resistant seal. Alternatively, the layer may include silicon dioxide, carbon oxides, carbon oxynitrides, metals, e.g., noble metals and alloys thereof, such as platinum, rhodium, iridium, and alloys thereof, metal suicides, nitrides, e.g., silicon nitrides, carbon nitrides, aluminum nitrides, titanium nitride, tungsten carbide or other carbides. The layer may be a single layer or made up of multiple layers of the same material or different materials. When multiple materials are employed, the coefficients of thermal expansion may also be calculated and designed so that they do not adversely affect the receiver component with which they are associated. In some instances, a conformal, void-free sealing layer covers at least a portion of the outer surface, if not the entire outer surface, of the receiver. In such instances, an electrical connection(s) may be present in the sealing layer to provide for electrical communication between components inside of the receiver and the external environment of the receiver.

Active Agent Delivery

[0246] Receivers of the invention may include an active agent delivery component. The active agent delivery component, when present, may vary. In some instances, the active agent delivery component may be a distinct component of the receiver, where the component may include a source of an active agent composition. The active agent composition may vary and include one or more active agents in combination with a carrier composition, where the carrier composition may be a liquid or solid composition and may be configured to provide for a controlled release delivery profile, as desired. Active agent delivery components of interest include, but are not limited to: solid delivery formats, such as patch and plaster delivery formats, and fluid introduction formats, such as iontophoretic formats and formats that employ a microneedle component, as described in greater detail below. For implantable receivers, any convenient active agent delivery format may be employed. Examples of active agent delivery formats of interest include, but are not limited to, those described in 1 1/897,931 ; the disclosure of which is herein incorporated by reference. Depending on the particular format, the delivery component may include a device component that provides for delivery of an amount of the active agent composition from the source to the patient. The device component may vary widely, where examples of device components include selective membranes, pumps, electric field sources, microneedles, etc. In certain instances, the active agent delivery component may be integrated with another component of the receiver. For example, where receivers include an adhesive component, the adhesive composition of the adhesive component may include one or more active agents, as desired, where the adhesive composition may be formulated to provide for any desired active agent delivery profile. Where active agent delivery is included, the receiver may be configured to deliver the active agent in accordance with a predetermined dosing schedule, in response a received dosing signal, in response to one or more detected physiological parameters (for example where the device is configured as a closed-loop active agent delivery device), etc.

Microneedle

[0247] Receivers of the invention may include a microneedle component, which microneedle component may be configured for analyte detection and/or active agent delivery, for example as described in greater detail below. Microneedle components of interest are configured for transfer of biological fluid from a physiological source to another location (for example external site) in a minimally-invasive, painless, and convenient manner. The microneedle components may be configured to permit in vivo sensing or withdrawal of biological fluids from the body, such as from or through the skin, with minimal or no damage, pain, or irritation to the tissue.

[0248] Microneedle components may include one or more microneedles (where multiple microneedles may be configured in any convenient format, such as in a three-dimensional array), a substrate to which the one or more microneedles are connected, a fluid chamber and/or a sensor in communication with the one or more microneedles.

[0249] The microneedles may be configured to function either as a conduit, a sensing element, or a combination thereof. Conduit microneedles can have a porous or hollow shaft. As used herein, the term "porous" means having pores or voids throughout at least a portion of the microneedle structure, sufficiently large and sufficiently interconnected to permit passage of fluid and/or solid materials through the microneedle. As used herein, the term "hollow" means having one or more substantially annular bores or channels through the interior of the microneedle structure, which have a diameter sufficiently large to permit passage of fluid and/or solid materials through the microneedle. The annular bores may extend throughout all or a portion of the needle in the direction of the tip to the base, extending parallel to the direction of the needle or branching or exiting at a side of the needle, as appropriate. A solid or porous microneedle can be hollow. Where desired, one or more of the microneedles may be coated (if solid, porous, or hollow) and/or at least partially filled (if porous or hollow) with a sensing or diffusion-modifying material.

[0250] The microneedles can be constructed from a variety of materials, including metals, ceramics, semiconductors, organics, polymers, and composites. Construction materials of interest include, but are not limited to: pharmaceutical grade stainless steel, gold, titanium, nickel, iron, tin, chromium, copper, palladium, platinum, alloys of these or other metals, silicon, silicon dioxide, and polymers. Biodegradable polymers of interest include, but are not limited to: polymers of hydroxy acids such as lactic acid and glycolic acid polylactide, polyglycolide, polylactide-co-glycolide, and copolymers with PEG, polyanhydrides, poly(ortho)esters, polyurethanes, poly(butyric acid), poly(valeric acid), and poly(lactide-co- caprolactone). Non-biodegradable polymers of interest include, but are not limited to: polycarbonate, polymethacrylic acid, ethylenevinyl acetate, polytetrafluoroethylene, and polyesters.

[0251] The microneedles can be configured with shafts that have a circular cross-section in the perpendicular, or the cross-section can be non- circular. For example, the cross-section of the microneedle can be polygonal (such as star-shaped, square, triangular), oblong, or another shape. The shaft can have one or more bores. The cross-sectional dimensions may vary, and in some instances range between 1 μm and 500 μm, such as between 10 μm and 100 μm. The outer and inner diameters may also vary, with the outer diameter ranging in some instances between 10 μm and 100 μm, and the inner diameter ranging in some instances between 3 μm and 80 μm. The length of the microneedles may also vary, ranging in some instances between 10 μm and 1 mm, such as between 100 μm and 500 μm, and including between 150 μm and 350 μm.

[0252] The substrate of the device can be constructed from a variety of materials, including metals, ceramics, semiconductors, organics, polymers, and composites. The substrate includes the base to which the microneedles are attached or integrally formed. Where desired, the substrate of the microneedle component can be integrated with another component of the receiver structure.

[0253] A fluid chamber (configured as a fluid collection chamber or an active agent depot) and/or sensor can be attached to the substrate or formed (for example, as part of the substrate) to communicate directly with the base of the microneedles.

[0254] The fluid chamber, when present, may be selectively in connection with the microneedle bores or pores, such that a biological fluid can flow from the tissue surrounding the microneedle, through the microneedle, and into the fluid chamber or an active agent composition can flow from the chamber through the microneedles and into the subject. Where desired, the fluid chamber is attached to, or integrated into, the substrate. The fluid chamber can be substantially rigid or readily deformable. The fluid chamber can be formed from one or more polymers, metals, ceramics, semiconductor, or combinations thereof. In one aspect, the fluid chamber contains a porous or absorbent material, such as a sponge, gel, or paper or polymeric strip. The fluid chamber may include a fluid active agent composition, which includes one or more active agents in combination with a carrier formulation. As such, the fluid chamber can initially be empty or can contain a gas or one or more reagents in any form (such as, liquid or solid particles) or active agent(s), etc., as desired.

[0255] Where desired, the microneedle component may include one or more sensors. The sensors can be located in the microneedle or body of the device (for example in the fluid chamber). The sensors can be in or attached to one or more microneedles, integrated into the substrate, or within or in communication with the fluid chamber. Sensors of interest include sensors of pressure, temperature, chemicals, pH, and/or electromagnetic fields. Sensor of interest include those configured to detect the presence of a chemical analyte in a biological fluid sample, where analytes of interest include, but are not limited to: blood sugar (glucose), cholesterol, bilirubin, creatine, various metabolic enzymes, hemoglobin, heparin, hematocrit, vitamin K or other clotting factors, uric acid, carcinoembryonic antigen or other tumor antigens, various reproductive hormones such as those associated with ovulation or pregnancy, drugs of abuse and/or metabolites thereof; blood alcohol concentration, etc. In certain aspects, substances or properties for which the receiver is configured to detect include lactate (important for athletes), oxygen, pH, alcohol, tobacco metabolites, and illegal drugs (important for both medical diagnosis and law enforcement). Sensors, when present, may be in communication with a microneedle sensor function module, which may include software and/or hardware components and present solely in the microneedle component and/or integrated, at least to some extent, into other parts of the receiver.

SYSTEMS

[0256] In certain aspects, the receivers are part of a body-associated system or network of devices, such as sensors, signal receivers, and optionally other devices, which may be internal and/or external, which provide a variety of different types of information that is ultimately collected and processed by a processor, such as an external processor, which then can provide contextual data about a living subject, such as a patient, as output. For example, the receiver may be a member of an in-body network of devices which can provide an output that includes data about IEM ingestion, one or more physiological sensed parameters, implantable device operation, etc., to an external collector of the data. The external collector, e.g., in the form of a health care network server, etc., of the data then combines this receiver provided data with additional relevant data about the patient, e.g., weight, weather, medical record data, etc., and may process this disparate data to provide highly specific and contextual patient specific data.

[0257] Systems of the invention include, in certain aspects, a signal receiver aspect of a receiver and one or more IEMs. IEMs of interest include those described in PCT application serial no. PCT/US2006/016370 published as WO/2006/1 16718; PCT application serial no. PCT/US2007/082563 published as WO/2008/052136; PCT application serial no. PCT/US2007/024225 published as WO/2008/063626; PCT application serial no. PCT/US2007/022257 published as WO/2008/066617; PCT application serial no. PCT/US2008/052845 published as WO/2008/095183; PCT application serial no. PCT/US2008/053999 published as WO/2008/101 107; PCT application serial no. PCT/US2008/056296 published as WO/2008/1 12577; PCT application serial no. PCT/US2008/056299 published as WO/2008/1 12578; and PCT application serial no. PCT/US2008/077753 published as WO 2009/042812; the disclosures of which applications are herein incorporated by reference.

[0258] In certain aspects the systems include an external device which is distinct from the receiver (which may be implanted or topically applied in certain aspects), where this external device provides a number of functionalities. Such an external device can include the capacity to provide feedback and appropriate clinical regulation to the patient. Such a device can take any of a number of forms. For example, the device can be configured to sit on the bed next to the patient, e.g., a bedside monitor. Other formats include, but are not limited to, PDAs, smart phones, home computers, etc.

[0259] An example of a system of the invention is shown in FIG. 15A. In FIG. 15A, system 1500 includes a pharmaceutical composition 1510 that comprises an IEM. Also present in system 1500 is signal receiver 1520, such as the signal receiver illustrated in FIGS. 10 to 12. Signal receiver 1520 is configured to detect a signal emitted from the identifier of the IEM 1510. Signal receiver 1520 also includes physiologic sensing capability, such as ECG and movement sensing capability. Signal receiver 1520 is configured to transmit data to a patient's an external device or PDA 1530 (such as a smart phone or other wireless communication enabled device), which in turn transmits the data to a server 1540. Server 1540 may be configured as desired, e.g., to provide for patient directed permissions. For example, server 1540 may be configured to allow a family caregiver 1550 to participate in the patient's therapeutic regimen, e.g., via an interface (such as a web interface) that allows the family caregiver 1550 to monitor alerts and trends generated by the server 1540, and provide support back to the patient, as indicated by arrow 1560. The server 1540 may also be configured to provide responses directly to the patient, e.g., in the form of patient alerts, patient incentives, etc., as indicated by arrow 1565 which are relayed to the patient via PDA 1530. Server 1540 may also interact with a health care professional (e.g., RN, physician) 1555, which can use data processing algorithms to obtain measures of patient health and compliance, e.g., wellness index summaries, alerts, cross- patient benchmarks, etc., and provide informed clinical communication and support back to the patient, as indicated by arrow 1580. 60] Another example of the system of the present invention is shown in Fig. 15B. FIG. 15B depicts a system that includes a syringe 15107, a receiver 15105, a glucometer 151 10, a wireless communication unit 151 15, communication links 15150B-E, and a dosage manager 15160. The system generally provides intelligent mechanisms for controlling the delivery of a dosage by the syringe 15107 (e.g., subcutaneous needle insertion or luer connection with an Intra Venous access device). This control may include, for example, detecting that the syringe 15107 is proximate to the patient, measuring the amount of the dose administered by the syringe 15107, communicating the measurement information to other devices, such as the receiver 15105, the glucometer 151 10, the wireless devices 151 15, and/or the dosage manager 15160, and providing feedback information to one or more of those devices. In some implementations, the feedback information may prevent the administration of the dosage to the patient using, for example, an interlock at the syringe 15107 to prevent giving the dosage. The syringe 15107 may, based on the feedback, output a visual indication (e.g., a light emitting diode (LED)) or an aural signal to indicate that the dosage is not to be administered to the patient. For example, the interlock mechanism, LED, and/or sound at the syringe 15107 may signal that the patient is receiving the wrong type of medication, receiving the dosage at the wrong time, and/or receiving the wrong amount of medication.

[0261] In some implementations, the syringe 15107 may be configured in an interlock mode as a default state to prevent the administration of a dosage until the dosage manager 15160 provides feedback information to unlock the syringe 15107 to allow the administration of the agent or medication.

[0262] Moreover, the syringe 15107 may, in some embodiments, include a measurement mechanism to provide measurement information representative of the amount of the dosage. When that is the case, the measurement information may be used by the dosage manager 160 along with other patient information, such as blood pressure, glucose level, heart rate, ingestible event marker (IEM) data, etc., to control when, and/or how much of, a dosage is provided to the patient. Furthermore, the syringe 15107 may activate the measurement mechanism (which provides the measured information) when the syringe 15107 is proximate to (e.g., enters or is close to) the patient's body, at which time the measurement information and other information, such as an identifier associated with the syringe 15107, a patient identifier, etc, are carried by a signal to other devices, such as the receiver 15105, the glucometer 151 10, and/or the wireless device 151 15, for communication to the dosage manager 15160. Moreover, these other devices may monitor the time when the dosage is administered by the syringe 15107. As such, the dosage manager 15160 may receive a precise time when the dosage is administered rather than rely on user-provided dosage administration times. As such, the system may be used to evaluate a specific fluid transfer event between a parenteral fluid delivery device, such as syringe 15107, and a patient [0263] In some aspects of systems of the invention, a receiver of the invention that includes a multi-purpose connector is operatively coupled to either a patient or another device via the multi-purpose connector. As reviewed above, other devices that the receiver may be operatively coupled to include, but are not limited to, an external charger device, an external programming device, an external data processing device, etc. In some instances, the system may include the receiver operatively coupled to a patient, either directly or to an external proximal end of a patient- associated device, such as an implanted medical device.

[0264] Where the receiver is operatively coupled to an external device, it may be directly connected to the external device or connected to the external device through one or more distinct connector devices, such as cables, cords or analogous structure. An example of an external device is an external programming device. The programming device may be configured to change the settings of the receiver. For example, the programming device may change the operating settings of the receiver, for example the parameters for signal measurement on the patient, frequency of measurement, duration of measurement, electrodes to use for measurement, etc. The programming device may also change the operating mode of the receiver. The programming device may also be able to send data to the receiver, such as medical records or other data about the patient. The programming device may be any device suitable for this purpose. Programming devices of interest include, but are not limited to, a computer with a built-in or peripheral monitor (such as may be found in a bedside monitor or a health information system), a personal digital assistant (PDA), a smart phone, a messaging device, or other handheld device, etc.

[0265] Systems of the invention may also include an external data processor configured to receive data from the receiver. The external data processor may receive the electrical signal data directly from the receiver, or via a data relay device (such as a device that receives data from the body-associated signal receiver and then forwards the received data to an extra-corporeal data processor). The external data processor may be configured to receive the data via any convenient wired or wireless protocol, as desired. Some external data processors of interest may receive data from the receiver by connecting to the multi-purpose connector. External data processors of interest are those that can receive the electrical signal data and process the data to produce useful information. The external data processor may also simply store the data for later processing or viewing. The processed data may be output to a user by any convenient medium, such as writing the data on paper, displaying the processed data to a user via a graphical user interface, and the like. The data may be arranged in any useful form, such as a graph, table, or signal. External data processors of the systems of the invention may take a variety of configurations, such as a computer with a built-in or peripheral monitor (for example as embodied in a bedside monitor or a health information system), a personal digital assistant (PDA), a smart phone, a messaging device, etc.

[0266] Systems of the invention enable a dynamic feedback and treatment loop of tracking medication timing and levels, measuring the response to therapy, and recommending altered dosing based on the physiology and molecular profiles of individual patients. For example, a symptomatic heart failure patient takes multiple drugs daily, primarily with the goal of reducing the heart's workload and improving patient quality of life. Mainstays of therapy include angiotensin converting enzyme (ACE) inhibitors, β-blockers and diuretics. For pharmaceutical therapy to be effective, it is vital that patients adhere to their prescribed regimen, taking the required dose at the appropriate time. Multiple studies in the clinical literature demonstrate that more than 50% of Class Il and III heart failure patients are not receiving guideline-recommended therapy, and, of those who are titrated appropriately, only 40-60% adhere to the regimen. With the subject systems, heart failure patients can be monitored for patient adherence to therapy, and adherence performance can be linked to key physiologic measurements, to facilitate the optimization of therapy by physicians.

[0267] In certain aspects, the systems of the invention may be employed to obtain an aggregate of information that includes sensor data and administration data. For example, one can combine the heart rate, the respiration rate, multi-axis acceleration data, something about the fluid status, and something about temperature, and derive indices that will inform about the total activity of the subject, that can be used to generate a physiological index, such as an activity index. For instance, when there is a rise in temperature, heart rate goes up a bit, and respiration speeds up, which may be employed as an indication that the person is being active. By calibrating this, the amount of calories the person is burning at that instant could be determined. In another example, a particular rhythmic set of pulses or multi-axis acceleration data can indicate that a person is walking up a set of stairs, and from that one can infer how much energy they are using. In another aspect, body fat measurement (e.g. from impedance data) could be combined with an activity index generated from a combination of measured biomarkers to generate a physiological index useful for management of a weight loss or cardiovascular health program. This information can be combined with cardiac performance indicators to get a good picture of overall health, which can be combined with pharmaceutical therapy administration data. In another aspect, one might find for example that a particular pharmaceutical correlates with a small increase in body temperature, or a change in the electrocardiogram. One can develop a pharmacodynamic model for the metabolism of the drug, and use the information from the receiver to essentially fit the free parameters in that model to give much more accurate estimation of the levels actually present in the serum of the subject. This information could be fed back to dosing regimens. In another aspect, one can combine information from a sensor that measures uterine contractions (e.g. with a strain gauge) and that also monitors fetal heart rate, for use as a high-risk pregnancy monitor. 68] In certain aspects, the subject specific information that is collected using the systems of the invention may be transmitted to a location where it is combined with data from one or more additional individuals to provide a collection of data which is a composite of data collected from two or more, e.g., five or more, ten or more, twenty five or more, fifty or more, one hundred or more, one thousand or more, etc., individuals. The composite data can then be manipulated, e.g., categorized according to different criteria, and made available to one or more different types of groups, e.g., patient groups, health care practitioner groups, etc., where the manipulation of data may be such as to limit the access of any given group to the type of data that group can access. For example, data can be collected from a hundred different individuals that are suffering from the same condition and taking the same medication. The data can be processed and employed to develop easy to follow displays regarding patient compliance with a pharmaceutical dosage regimen and general health. Patient members of the group can access this information and see how their compliance matches with other patient members of the group, and whether they are enjoying the benefits that others are experiencing. In yet another aspect, doctors can also be granted access to a manipulation of the composite data to see how their patients are matching up with patients of other doctors, and obtain useful information on how real patients respond to a given therapeutic treatment regimen. Additional functionalities can be provided to the groups given access to the composite data, where such functionalities may include, but are not limited to: ability to annotate data, chat functionalities, security privileges, etc.

[0269] The receivers may be part of the systems described in PCT Application Serial No. PCT/US08/85048; PCT Application Serial No. PCT/US2007/024225 published as WO 2008/095183; PCT Application Serial No. PCT/US2007/024225 published as WO 2008/063626 and PCT Application Serial No. US2006/016370 published as WO 2006/116718; the disclosures of which are herein incorporated by reference.

[0270] In accordance with another aspect of the present invention, the receivers may be implemented in various ways, including an implantable device, a semi-implantable device, such as a subcutaneous device, and an externally applied or positioned device, such as a personal signal receiver and each may be used on conjunction with a dosage deliver system. Examples of receiver configurations of interest include, but are not limited to, those described in PCT Application Serial No. PCT/US08/85048 published as WO 2009/070773; PCT Application Serial No. PCT/US2007/ 052845 published as WO 2008/095183; PCT Application Serial No. PCT/US2007/024225 published as WO 2008/063626 and PCT Application Serial No. US2006/016370 published as WO 2006/1 16718; the disclosures of which are herein incorporated by reference. One example of a personal signal receiver for use with dosage delivery systems is a "patch" receiver removably affixed to the skin or apparel of a user. Other implementations include a wristband or an IV access device. In some implementations, the receivers may be implemented as a personal health signal receiver associated with the body, e.g., located inside, or within close proximity to a body, configured to receive and decode a signal from an in vivo transmitter located inside the body.

[0271] The receivers in accordance with the teaching of the present invention may also be configured to receive information from other sources as well, such as intelligent event marker (IEM) data. When that is the case, the receiver 105 may detect data associated with an IEM event, such as the administration of medication including a radio frequency identifier-like marker, process and forward the data to another device, such as glucometer 1 10 and/or wireless device 1 15, for further processing and forwarding to dosage manager 160.

[0272] In certain aspects, the system further includes an element for storing data, i.e., a data storage element. The data storage element may be a computer readable medium. The term "computer readable medium" as used herein refers to any physical storage or transmission medium that participates in providing instructions and/or data to a computer for execution and/or processing. Examples of storage media include floppy disks, magnetic tape, CD-ROM, a hard disk drive, a ROM or integrated circuit, a magneto-optical disk, or a computer readable card such as a PCMCIA card and the like, whether or not such devices are internal or external to the computer. A file containing information may be "stored" on computer readable medium, where "storing" means recording information such that it is accessible and retrievable at a later date by a computer. With respect to computer readable media, "permanent memory" refers to memory that is permanent. Permanent memory is not erased by termination of the electrical supply to a computer or processor. Computer hard-drive ROM (i.e. ROM not used as virtual memory), CD-ROM, floppy disk and DVD are all examples of permanent memory. Random Access Memory (RAM) is an example of non-permanent memory. A file in permanent memory may be editable and re-writable.

[0273] The invention also provides computer executable instructions (i.e., programming) for performing the above methods. The computer executable instructions are present on a physical computer readable medium. Accordingly, the invention provides a computer readable medium containing programming for use in detecting and processing a signal generated by a composition of the invention, e.g., as reviewed above.

[0274] As reviewed above, in certain aspects of interest, the receiver includes a semiconductor support component. Any of a variety of different protocols may be employed in manufacturing the receiver structures and components thereof. For example, molding, deposition and material removal, e.g., planar processing techniques, such as Micro-Electro- Mechanical Systems (MEMS) fabrication techniques, including surface micromachining and bulk micromachining techniques, may be employed. Deposition techniques that may be employed in certain aspects of fabricating the structures include, but are not limited to: electroplating, cathodic arc deposition, plasma spray, sputtering, e-beam evaporation, physical vapor deposition, chemical vapor deposition, plasma enhanced chemical vapor deposition, etc. Material removal techniques included, but are not limited to: reactive ion etching, anisotropic chemical etching, isotropic chemical etching, planarization, e.g., via chemical mechanical polishing, laser ablation, electronic discharge machining (EDM), etc. Also of interest are lithographic protocols. Of interest in certain aspects is the use of planar processing protocols, in which structures are built up and/or removed from a surface or surfaces of an initially planar substrate using a variety of different material removal and deposition protocols applied to the substrate in a sequential manner. Illustrative fabrication methods of interest are described in greater detail in copending PCT application serial no. PCT/US2006/ 016370; the disclosure of which is herein incorporated by reference. [0275] In certain aspects, off-the-shelf components may be employed to fabricate the receivers or components thereof. For example, an off-the- shelf instrumentation amplifier for the input amp may be employed, e.g., in bare die form. Custom logic, either in an FPGA or in an ASIC, that handles the demodulator, the memory, the microprocessor functions, and all the interface functions may be used. The transmitter may be an off-the- shelf chip, e.g., in the mixed communication band, which is approved for medical implants. The clock may be a stand-alone clock, or the device may have a microprocessor that has a clock built in.

[0276] Aspects of the invention further include methods of using receivers. In methods of receivers, a receiver receives an input signal in some manner, where the input signal may vary. Examples of input signals include, but are not limited to: transbody conductively received signals (such as may be received from an IEM or smart parenteral device), signals obtained by device sensors, such as physiological parameter and/or environmental signals, etc. Various aspects of the invention further include the device acting in some manner in response to receiving the input signal, e.g., relaying a signal to a second device, delivering an active agent to a subject with which the device is associated, etc.

[0277] In some methods of invention, as an optional step, a signal is first conductively transmitted from an in vivo transmitter, such as an IEM. The transmitted signal is then received by the receiver, where it may be stored to a memory, retransmitted to another receiver, output to a user, e.g., either directly or via a third device, e.g., an external PDA, etc. In the methods of the subject invention in which the in vivo transmitter is an IEM, the IEM is administered as desired, via ingestion.

[0278] The subject methods find use in the treatment of a variety of different conditions, including disease condition applications. The specific disease conditions treatable by with the subject compositions are as varied as the types of active agents that can be present in the subject compositions. Thus, disease conditions include, but are not limited to: cardiovascular diseases, cellular proliferative diseases, such as neoplastic diseases, autoimmune diseases, hormonal abnormality diseases, infectious diseases, pain management, neurological diseases, e.g., epilepsy, and the like.

[0279] By treatment is meant at least an amelioration of the symptoms associated with the disease condition afflicting the subject, where amelioration is used in a broad sense to refer to at least a reduction in the magnitude of a parameter, e.g. symptom, associated with the pathological condition being treated. As such, treatment also includes situations where the pathological condition, or at least symptoms associated therewith, are completely inhibited, e.g. prevented from happening, or stopped, e.g. terminated, such that the subject no longer suffers from the pathological condition, or at least the symptoms that characterize the pathological condition. Accordingly, "treating" or "treatment" of a disease includes preventing the disease from occurring in an animal that may be predisposed to the disease but does not yet experience or exhibit symptoms of the disease (prophylactic treatment), inhibiting the disease (slowing or arresting its development), providing relief from the symptoms or side-effects of the disease (including palliative treatment), and relieving the disease (causing regression of the disease).

[0280] A variety of subjects are treatable according to the present methods. Generally such subjects are "mammals" or "mammalian," where these terms are used broadly to describe organisms which are within the class mammalia, including the orders carnivore (e.g., dogs and cats), rodentia (e.g., mice, guinea pigs, and rats), and primates (e.g., humans, chimpanzees, and monkeys). In representative aspects, the subjects will be humans.

[0281] In certain aspects, the subject methods, as described above, are methods of managing a disease condition, e.g., over an extended period of time, such as one week or longer, one month or longer, six months or longer, one year or longer, two years or longer, five years or longer, etc. The subject methods may be employed in conjunction with one or more additional disease management protocols, e.g., electrostimulation based protocols in cardiovascular disease management, such as pacing protocols, cardiac resynchronization protocols, etc; lifestyle, such a diet and/or exercise regimens for a variety of different disease conditions; etc. [0282] In certain aspects, the methods include modulating a therapeutic regimen based data obtained from the compositions. For example, data may be obtained which includes information about patient compliance with a prescribed therapeutic regimen. This data, with or without additional physiological data, e.g., obtained using one or more sensors, such as the sensor devices described above, may be employed, e.g., with appropriate decision tools as desired, to make determinations of whether a given treatment regimen should be maintained or modified in some way, e.g., by modification of a medication regimen and/or implant activity regimen. As such, methods of invention include methods in which a therapeutic regimen is modified based on signals obtained from the composition(s).

[0283] In certain aspects, also provided are methods of determining the history of a composition of the invention, where the composition includes an active agent, an identifier element and a pharmaceutically acceptable carrier. In certain aspects where the identifier emits a signal in response to an interrogation, the identifier is interrogate, e.g., by a wand or other suitable interrogation device, to obtain a signal. The obtained signal is then employed to determine historical information about the composition, e.g., source, chain of custody, etc. In certain aspects, this determining step may include accessing a database or analogous compilation of stored history for the composition.

[0284] Receivers of the invention find use in a variety of different applications. Medical aspects of the present invention provide the clinician an important new tool in their therapeutic armamentarium: automatic detection and identification of pharmaceutical agents actually delivered into the body. The applications of this new information device and system are multi-fold. Applications include, but are not limited to: (1 ) monitoring patient compliance with prescribed therapeutic regimens; (2) tailoring therapeutic regimens based on patient compliance; (3) monitoring patient compliance in clinical trials; (4) monitoring usage of controlled substances; and the like. Each of these different illustrative applications is reviewed in greater detail below in PCT Application Serial No. PCT/US08/85048; PCT Application Serial No. PCT/US2007/024225 published as WO 2008/095183; PCT Application Serial No. PCT/US2007/024225 published as WO 2008/063626 and PCT Application Serial No. US2006/016370 published as WO 2006/116718; the disclosures of which are herein incorporated by reference.

[0285] Receivers of interest also find use in conjunction with delivery of therapeutic fluids to a subject. Of interest is the use of the receivers in conjunction with smart parenteral delivery devices, such as described in PCT application serial no. PCT/US2007/015547 published as WO 2008/008281 ; the disclosure of which is herein incorporated by reference. When used in conjunction with such fluid delivery devices (such as a smart parenteral device), the receiver may be configured to receive data regarding the actual amounts of therapeutic fluid that has been administered. The receiver may be configured to combine this particular data with other relevant data, such as analyte testing data, physiological data, etc., where these additional types of data may be obtained with the receiver or another type of test, such as a dedicated home use analyte testing device, etc. Furthermore, the receiver may be configured to take one or more actions based on the received information, including but not limited to: relay data to a second device, modify a therapeutic regimen, etc.

[0286] Also of interest are applications in which the receivers are not used to receive a signal from an IEM or smart-parenteral delivery system. One such application of interest in which receivers of the invention find use is in epileptic seizure detection. Such devices include an epileptic seizure detection module, which module is configured to employ one or more types of received data to determine whether the subject is about to or is suffering from an epileptic seizure. Accordingly, in these applications, one or more types of physiological data are obtained with the receiver and processed to determine whether the subject is about to or is suffering from an epileptic seizure. In other words, the receiver employs obtained physiological data to make a seizure prediction or detect a seizure occurrence. Physiological data that may be obtained and used in these applications include electroencephalograph^ (EEG) data, accelerometer data, heart rate (ECG) data, etc. A single type of data may be obtained or two or more different types of data may be obtained and processed to make a determination as to whether a subject is about or is suffering from an epileptic seizure. In some instances, data obtained by the receiver may be combined with data from other sources and processed to make the determination. Data may include, for example, a distinctive signature on the accelerometer or heart rate variability. Sensor data may be integrated from the EEG, either as part of the system or as an ancillary input, as desired. With multiple data streams one can detect "kindling," the set of events that lead up to a seizure. In such instances, medical therapy may be adjusted based on seizure state, as desired. Neuromodulation devices may be adapted to these needs - measuring EEG or adjusting therapy.

[0287] The receiver may be configured to make the determination using any convenient protocol. One or more algorithms may be employed which use the obtained physiological data to make a determination as to whether a seizure is about to occur or is occurring. Examples of such algorithms include, but are not limited to: algorithms for automated seizure warning (ASWAs)(for example as described in published United States Patent No. 20070213786); algorithms for detecting chirp-like time-frequency variations in an EEG signal (for example as described in Sen et al., "Analysis of Seizure EEG in kindled epileptic rats," Computational and Mathematical Methods in Medicine, Volume 8, Issue 4 December 2007 , pages 225 - 234; etc.

[0288] In such applications, prediction or detection of an epileptic seizure may result in a number of additional actions. In some instances, the receiver may be configured to produce and emit an alert signal. The alert signal may or may not be detectable to the subject. For example, the alert signal may take the form of an audible or visual signal which can be detected by the subject. The alert signal may also be a signal that is sent to a health care profession or other person, e.g., via a wireless communication protocol. The alert signal may be employed in a number of different ways, e.g., to alert a health care profession to provide assistance to the subject, to instigate or modify a therapeutic regimen, etc.

[0289] In some instances, the receiver is configured as a "closed-loop" epileptic therapy device, where the receiver includes an epileptic therapeutic component, such as a pharmacological or electrical therapeutic component. In these instances, the prediction or detection of the epileptic seizure may be employed by the receiver to instigate epileptic therapy (for example by delivery of an active agent and/or electrical stimulation or by directing another device to take one or more of such actions). Alternatively, an existing epileptic therapy protocol may be modified based on the predicted or detected seizure, e.g., in terms of dosage, duration, etc.

[0290] Receivers of the invention also find use in tracking applications, in which one or more persons, e.g., patients, soldiers, etc., are monitored over a given period of time. Receivers employed in these aspects may include a number of a different physiological and/or environmental sensing modules, such as the accelerometer and ECG sensing modules described above, in order to monitor health status of a subject over time. This data may be combined with positional data, e.g., as provided by a GPS module, in order to track a subject with respect to location as a function of time.

[0291] One specific type of tracking application of interest is the tracking personnel, e.g., work personnel in an active employment setting, such as military personnel in a battlefield setting, fire and rescue personnel in a fire setting, health care personnel in a hospital, etc. In such applications, receivers of the invention may include functional modules for determining certain physiological states which are common in the setting of interest. For example, functional modules for determining certain physiological states which are common battlefield conditions may be present. Examples of such functional modules include the accelerometer and ECG functional modules described above, as these particular functional modules provide useful data regarding mobility and vital activity. When one or more of critical limits are reached in or more physiological states of interest (for example the soldier is no longer mobile and/or vital sign activity is no longer adequate), the receiver may be configured to send a warning signal to a leader/medic unit, thereby indicating that a soldier is in need of immediate care. For example, if temperature sensors of the receiver indicate cold weather and that the soldier's body temperature has begun to fall below a specified minimum, receiver may automatically signal the leader/medic unit and a command unit that the soldier is likely suffering from hypothermia. The leader or medic operating the leader/medic unit or a person operating the central control unit may then notify other soldiers or medical personnel in the area that the soldier should be treated for the condition as soon as possible. Similarly, a wounded soldier can be monitored for symptoms and severity of injury or shock ensuing from blood loss.

[0292] In these applications, each receiver may be customized to the particular wearer. Thus, a given receiver may contain information about the individual such as allergies to medications and other medical information which would be important to medical personnel treating the individual. Additionally, the receiver may keep a short physiological history, such as the body temperature, heart rate, body positions, blood pressure, oxygen saturation and movement for the last four hours or some other time period. The information can be forwarded to a field leader/medic unit or the command unit upon request. This can be accomplished either by the remote communications system of the receiver, or by a direct link-up between the receiver and the leader/medic unit when a medic having a leader/medic unit, arrives to treat the user.

[0293] In these applications, the receiver or leader/medic unit could include software/firmware for providing guidance and medical decision support. Additionally, a microprocessor disposed therein, or in the receiver, could be programmed to control fluid infusion, drug delivery, and ventilator support for the patient, thereby enabling efficacious treatment even under battlefield conditions. The receiver may communicate via a variety of predetermined schemes, e.g., with the leader/medic unit or command unit either continuously or in brief bursts so as to prevent enemy combat forces from tracking the communications to locate the soldier. The bursts may occur periodically on schedule, or as indicated by the leader/medic control unit or command unit.

[0294] In these applications, the leader/medic unit may be a portable device worn by medics and other leaders to allow each to monitor those for whom they are responsible. The leader/medic unit may contain a communications system for communicating with the receivers and the command units, and/or may contain a display which allows the user to graphically monitor the locations of personnel on the battlefield, and/or to view the physiological conditions of each soldier within the command structure for that leader. The leader/medic unit may receive information as to the location of the injured soldier, and may receive medical information while the medic is relocating to the site of the soldier. When used by a medic, this unit enables the medic to view vital signs and other information about the injured soldier prior to actually examining the soldier. Thus, the medic is able to conduct an initial evaluation of the injured soldier while in transit to the soldier's location. Additionally, because the receiver also communicates with the command unit, medical personnel at a central command post can instruct the medic on diagnosis and treatment options as the medic is en route to the casualty. By continually monitoring the location and status of the soldiers, significant decreases in casualty rates can be achieved. Additionally, the technology used in the present invention can be modified slightly to maintain high levels of care in civilian medical applications while significantly decreasing the costs.

[0295] While the above description has been provided in terms of tracking military personnel, the receivers may be employed in tracking any type of personnel, particular in an active work setting in which the personnel are located at a stationary position for extended periods of time.

[0296] Non-personnel tracking applications are also provided. Receivers may be employed in hospital settings for patient tracking and management. Rather than requiring nurses to track down patients to take their vital signs, the receivers may be employed by nurses or other health care practitioners to determine a patients' location, as well as their vital signs. If the information received indicated a problem, the location of the patient could be readily determined. Thus, a smaller number of nurses could be used while providing a higher level of care.

[0297] Also provided are kits for practicing the subject methods. Kits may include one or more receivers of the invention, as described above. In addition, the kits may include one or more dosage compositions, e.g., in the form of IEM compositions. The dosage amount of the one or more pharmacological agents provided in a kit may be sufficient for a single application or for multiple applications. Accordingly, in certain aspects of the subject kits a single dosage amount of a pharmacological agent is present and in certain other aspects multiple dosage amounts of a pharmacological agent may be present in a kit. In those aspects having multiple dosage amounts of pharmacological agent, such may be packaged in a single container, e.g., a single tube, bottle, vial, and the like, or one or more dosage amounts may be individually packaged such that certain kits may have more than one container of a pharmacological agent.

[0298] In certain aspects, the kits may also include an external monitor device, e.g., as described above, which may provide for communication with a remote location, e.g., a doctor's office, a central facility etc., which obtains and processes data obtained about the usage of the composition.

[0299] The subject kits may also include instructions for how to practice the subject methods using the components of the kit. The instructions may be recorded on a suitable recording medium or substrate. For example, the instructions may be printed on a substrate, such as paper or plastic, etc. As such, the instructions may be present in the kits as a package insert, in the labeling of the container of the kit or components thereof (i.e., associated with the packaging or sub-packaging) etc. In other aspects, the instructions are present as an electronic storage data file present on a suitable computer readable storage medium, e.g. CD-ROM, diskette, etc. In yet other aspects, the actual instructions are not present in the kit, but means for obtaining the instructions from a remote source, e.g. via the internet, are provided. An example of this aspect is a kit that includes a web address where the instructions can be viewed and/or from which the instructions can be downloaded. As with the instructions, this means for obtaining the instructions is recorded on a suitable substrate.

[0300] Some or all components of the subject kits may be packaged in suitable packaging to maintain sterility. In many aspects of the subject kits, the components of the kit are packaged in a kit containment element to make a single, easily handled unit, where the kit containment element, e.g., box or analogous structure, may or may not be an airtight container, e.g., to further preserve the sterility of some or all of the components of the kit. [0301] It is to be understood that this invention is not limited to particular aspects described, as such may vary. It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting, since the scope of the present invention will be limited only by the appended claims. Where a range of values is provided, it is understood that each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the invention. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the invention, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. Although any methods and materials similar or equivalent to those described herein can also be used in the practice or testing of the present invention, representative illustrative methods and materials are now described. All publications and patents cited in this specification are herein incorporated by reference as if each individual publication or patent were specifically and individually indicated to be incorporated by reference and are incorporated herein by reference to disclose and describe the methods and/or materials in connection with which the publications are cited. The citation of any publication is for its disclosure prior to the filing date and should not be construed as an admission that the present invention is not entitled to antedate such publication by virtue of prior invention. Further, the dates of publication provided may be different from the actual publication dates which may need to be independently confirmed.

[0302] It is noted that, as used herein and in the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. It is further noted that the claims may bθ drafted to exclude any optional element. As such, this statement is intended to serve as antecedent basis for use of such exclusive terminology as "solely," "only" and the like in connection with the recitation of claim elements, or use of a "negative" limitation. As will be apparent to those of skill in the art upon reading this disclosure, each of the individual aspects described and illustrated herein has discrete components and features which may be readily separated from or combined with the features of any of the other several aspects without departing from the scope or spirit of the present invention. Any recited method can be carried out in the order of events recited or in any other order which is logically possible.Although the foregoing invention has been described in some detail by way of illustration and example for purposes of clarity of understanding, it is readily apparent to those of ordinary skill in the art in light of the teachings of this invention that certain changes and modifications may be made thereto without departing from the spirit or scope of the appended claims. Accordingly, the preceding merely illustrates the principles of the invention. It will be appreciated that those skilled in the art will be able to devise various arrangements which, although not explicitly described or shown herein, embody the principles of the invention and are included within its spirit and scope. Furthermore, all examples and conditional language recited herein are principally intended to aid the reader in understanding the principles of the invention and the concepts contributed by the inventors to furthering the art, and are to be construed as being without limitation to such specifically recited examples and conditions. Moreover, all statements herein reciting principles, aspects, and aspects of the invention as well as specific examples thereof, are intended to encompass both structural and functional equivalents thereof. Additionally, it is intended that such equivalents include both currently known equivalents and equivalents developed in the future, i.e., any elements developed that perform the same function, regardless of structure. The scope of the present invention, therefore, is not intended to be limited to the exemplary aspects shown and described herein. Rather, the scope and spirit of present invention is embodied by the appended claims.