CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. provisional patent application No. 62/613,112, filed on January 3, 2018, and entitled "SYSTEMS FOR MONITORING ACTIVITY OF AN INDIVIDUAL AND RELATED METHODS," the disclosure of which is expressly incorporated herein by reference in its entirety.

BACKGROUND

[0002] Assistive technologies are products that assist users in overcoming limitations on their ability to function in the workplace, home, or other non-institutional setting. The goal of the technology is to aid with everyday living and functioning, but not to ameliorate a disease state. The assistive technology market sector includes a broad range in devices, from large-print books to wireless monitoring devices. In the United States, the market is projected to grow from $43.1 billion in 2015 to $58.3 billion in 2020 (Compound annual growth rate (CAGR): 6.2%).

[0003] There are many types of assistive devices including wheelchairs/scooters, which are found within the "Mobility Aids" sector. The "Mobility" sub-sector is expected to exceed $3.9 billion in 2020, with a CAGR of 2.8%. Wheelchairs and scooters account for 44% of this market, with powered wheelchairs taking up the largest component of that sector with 29% of the market. The drivers of the market include aging populations, obesity, and medical conditions in younger people that include strokes, osteoarthritis, loss of limbs, and other diseases.

SUMMARY

[0004] An example system (e.g., pressure sensing mat) for monitoring activity of an individual is described herein. This disclosure contemplates that the system can be incorporated into a mobile assistance device such as a wheelchair or scooter (e.g., in a seat thereof). The system can include a plurality of sensor pads, and a controller operably coupled to the sensor pads. Each of the sensor pads can include a flexible substrate, a plurality of coplanar electrodes arranged on the flexible substrate, and a conductive ink having variable resistivity arranged on the flexible substrate. The coplanar electrodes can be electrically connected by the conductive ink. Additionally, the controller can include a processor and memory operably coupled to the processor. The processor can execute instructions stored on the memory such that the processor is configured to receive a respective signal from each of the sensor pads, and characterize activity of the individual based on the respective signals.

[0005] In some implementations, the coplanar electrodes include a plurality of elongate interdigitated fingers.

[0006] Alternatively or additionally, the sensor pads can be arranged at approximate locations of a plurality of anatomical landmarks of the individual. For example, the anatomical landmarks can be a femur (e.g., left and/or right femur), an ischial tuberosity (e.g., left and/or right ischial tuberosity), or a sacrum of the individual. In some implementations, at least two of the sensor pads can optionally be arranged at the approximate location of a ischial tuberosity (e.g., left and/or right ischial tuberosity) of the individual.

[0007] Alternatively or additionally, the controller can further include a potentiometer configured to adjust a sensitivity of at least one of the sensor pads.

[0008] Alternatively or additionally, the controller can further include a multiplexer configured to individually select each of the sensor pads for measurement.

[0009] Alternatively or additionally, the system can further include a rechargeable battery.

[0010] Alternatively or additionally, each of the sensor pads can be hermetically sealed, for example laminated between sheets of polymer.

[0011] Alternatively or additionally, the step of characterizing activity of the individual based on the respective signals can include predicting changes in a postural position of the individual. For example, the postural position of the individual can be a neutral posture, an anterior pelvic tilt posture, a posterior pelvic tilt posture, a pelvic rotation posture, a pelvic obliquity posture, a forward lean posture, or a side lean posture. In some implementations, changes in a postural position of the individual can be predicted by applying a moving average filter to the respective signals, and detecting a percentage change in one or more of the respective signals relative to a threshold level.

[0012] Alternatively or additionally, the processor can be further configured to measure frequency or duration of the changes in the postural position of the individual.

[0013] Alternatively or additionally, the processor can be further configured to generate display data representing a respective relative pressure applied to each of the sensor pads.

[0014] Alternatively or additionally, the conductive ink can be a carbon based conductive ink.

[0015] It should be understood that the above-described subject matter may also be implemented as a computer-controlled apparatus, a computer process, a computing system, or an article of manufacture, such as a computer-readable storage medium.

[0016] Other systems, methods, features and/or advantages will be or may become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features and/or advantages be included within this description and be protected by the accompanying claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The components in the drawings are not necessarily to scale relative to each other. Like reference numerals designate corresponding parts throughout the several views.

[0018] FIGURE 1 illustrates an example activity monitoring system according to implementations described herein. [0019] FIGURES 2A and 2B illustrate coplanar electrodes for use in the activity monitoring system of Fig. 1. Fig. 2A is a plan view of the coplanar electrodes. Fig. 2B is a perspective view of the coplanar electrodes.

[0020] FIGURE 3 illustrates an example computing device.

[0021] FIGURE 4 illustrates the original SitSmart prototype .

[0022] FIGURE 5 illustrates another SitSmart prototype including coplanar electrodes and Kapton sealing layers according to an implementation described herein.

[0023] FIGURE 6 illustrates another SitSmart prototype including coplanar electrodes and Kapton sealing layers according to an implementation described herein.

[0024] FIGURE 7 illustrates another SitSmart prototype configured for standard connectivity according to an implementation described herein.

[0025] FIGURE 8 illustrates an example controller for use with the original SitSmart prototype of Fig. 4.

[0026] FIGURE 9 illustrates an example controller for use with the SitSmart prototype of

Fig. 5.

[0027] FIGURE 10 illustrates an example controller for use with the SitSmart prototype of Fig. 6.

[0028] FIGURE 11 illustrates an example controller for use with the SitSmart prototype of Fig. 7.

[0029] FIGURE 12 illustrates an example controller for use with the activity monitoring system of Fig. 1.

[0030] FIGURES 13A and 13B illustrate graphical representations of the layout of the sensor pads of the activity monitoring system of Fig. 1

[0031] FIGURE 14 illustrates an example SitSmart App user interface according to an implementation described herein. [0032] FIGURE 15 illustrates modeling and data interpretation of sensor signals measured by the sensor pads of the activity monitoring system of Fig. 1.

[0033] FIGURE 16 illustrates fitted response to a step input at multiple postures at one of the sensor pads of the activity monitoring system of Fig. 1.

[0034] FIGURE 17 is a table of first order model characteristics for a step response at each of the sensor pads of the activity monitoring system of Fig. 1.

[0035] FIGURE 18 illustrates relative sensitivity of the sensor pads on different cushions.

[0036] FIGURE 19 illustrates results of dynamic testing of the activity monitoring system of Fig. 1 with predictive algorithm.

[0037] FIGURES 20A-20C are schematic circuit diagrams that illustrate a Processor & Memory Unit (Fig. 20A), a Power Management Unit (Fig. 20B), and a Signal Conditioning Unit (Fig. 20C) of the activity monitoring system controller of Fig. 1.

DETAILED DESCRIPTION

[0038] 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. Methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present disclosure. As used in the specification, and in the appended claims, the singular forms "a," "an," "the" include plural referents unless the context clearly dictates otherwise. The term "comprising" and variations thereof as used herein is used synonymously with the term "including" and variations thereof and are open, non-limiting terms. The terms "optional" or "optionally" used herein mean that the subsequently described feature, event or circumstance may or may not occur, and that the description includes instances where said feature, event or circumstance occurs and instances where it does not. Ranges may be expressed herein as from "about" one particular value, and/or to "about" another particular value. When such a range is expressed, an aspect includes from the one particular value and/or to the other particular value. Similarly, when values are expressed as approximations, by use of the antecedent "about," it will be understood that the particular value forms another aspect. It will be further understood that the endpoints of each of the ranges are significant both in relation to the other endpoint, and independently of the other endpoint. While implementations will be described for a wheelchair incorporating an activity monitoring system, it will become evident to those skilled in the art that the implementations are not limited thereto, but are applicable for other applications including, but not limited to, other mobile assistance devices (e.g., scooters) and patient beds.

[0039] Referring now to Fig. 1, an example system (also sometimes referred to as a "pressure sensing mat") for monitoring activity of an individual is shown. As described herein, the system can be incorporated into a mobile assistance device such as a wheelchair or scooter (e.g., in a seat thereof). This disclosure contemplates that the system can be incorporated into other devices where there is a desire to measure contact force(s) at the interface between a user and a device, e.g., the interface between a user's lower extremities and the seat of a wheelchair as described in the examples below. Alternatively, the system can be incorporated into other devices including, but not limited to, a bed (e.g., in or on a mattress thereof). The pressure sensing mat can include a plurality of sensor pads 102A-102G (collectively referred to herein as "sensor pads 102"), and a controller 104 operably coupled to the sensor pads 102. Fig. 1 illustrates opposite sides of the pressure sensing mat, e.g., showing top of the sensor pads 102 on the right hand side of Fig. 1, and showing bottom of the sensor pads 102 on the left hand side of Fig. 1. Optionally, in some implementations, each of the sensor pads 102 can be hermetically sealed, for example laminated between sheets of polymer. For example, this disclosure contemplates hermetically sealing the sensor pads 102 with a polyamide such as Kapton (yellow-tinted polyamide) or a polypropylene-like variant that is clear in color. It should be understood that these materials are provided only as examples and that other materials can be used to seal the sensor pads 102. The encapsulation of all sensor pads 102 protects the pressure sensing mat from moisture and other environmental effects, which would otherwise compromise the functionality of the pressure sensing mat. The system can be used to provide real-time feedback to an individual (e.g., patient) and/or the individual's caregivers (e.g., medical provider). The real-time feedback can be provided locally, for example at a computing device such a mobile phone or tablet computing device of the individual, and/or remotely over a network, for example telehealth.

[0040] The sensor pads 102 can be arranged at approximate locations of a plurality of anatomical landmarks of an individual. This disclosure contemplates that the individual can be a person using the mobile assistance device into which the system of Fig. 1 is incorporated, for example. In one implementation, the anatomical landmarks can be a femur (e.g., left and/or right femur), an ischial tuberosity (e.g., left and/or right ischial tuberosity), or a sacrum of the individual. As shown in Fig. 1, the system includes seven sensor pads 102, where sensor pads 102A and 102B are arranged at the approximate locations of the individual's right and left femurs, sensor pads 102C-102F are arranged at the approximate locations of the individual's right and left ischial tuberosities, and sensor pad 102G is arranged at the approximate location of the individual's sacrum. As shown in Fig. 1, a plurality of sensor pads can optionally be arranged at the approximate location of one anatomical landmark, e.g., two sensor pads are arranged at the approximate locations of each ischial tuberosity of the individual. Additionally, the sensor pads 102 can optionally be sized and/or shaped differently depending on the anatomical landmark. For example, as shown in Fig. 1, sensor pads 102A and 102B (i.e., pads for sensing pressure at the individual's femurs) have a different size as compared to sensor pads 102C-102F (i.e., pads for sensing pressure at the individual's ischial tuberosities) or sensor pad 102G (i.e., pad for sensing pressure at the individual's sacrum). It should be understood that the number, size, shape, and/or arrangement of the sensor pads 102 shown in Fig. 1 are provided only as an example. This disclosure contemplates a system having a different number, size, shape, and/or arrangement of sensor pads.

[0041] As shown in Fig. 1, each of the sensor pads 102 can include a flexible substrate 106, a plurality of coplanar electrodes 108 arranged on the flexible substrate 106, and a conductive ink 110 having variable resistivity arranged on the flexible substrate 106. In some implementations, the coplanar electrodes 108 can optionally be conductive ink such as a silver-based conductive ink, for example. It should be understood that silver-based conductive ink is provided only as an example and that the coplanar electrodes 108 can be made of other materials. In Fig. 1, the coplanar electrodes 108 and conductive ink 110 are only labeled with respect to sensor pad 102A. It should be understood that each of the other sensor pads 102B-102G includes coplanar electrodes 108 and conductive ink 110. In some implementations, the flexible substrate 106 can optionally be a printed circuit board, and the coplanar electrodes 108 can be conductive traces provided thereon.

In some implementations, the coplanar electrodes 108 can be formed of conductive ink and applied to the flexible substrate 106 by printing, for example. The coplanar electrodes 108 can be provided on the same surface of the flexible substrate 106. Alternatively or additionally, the coplanar electrodes 108 can be a pair of coplanar electrodes having a plurality of elongate interdigitated fingers, where each one of the pair of coplanar electrodes has a trunk (e.g., reference characters 108A and 108B shown in Figs. 2A-2B) with a plurality of elongate fingers extending in a direction substantially perpendicular to the trunk. The elongate fingers of each one of the pair of coplanar electrodes can be interdigitated with elongate fingers of the other. As described herein, the geometrical parameters of the coplanar electrodes 108 (e.g., surface area and/or spacing between electrodes) can be selected to obtain a desired level of pressure sensing sensitivity. This disclosure contemplates that the flexible substrate 106 can be made of materials including, but not limited to, polymer, polyester, and fabric-based material. Additionally, this disclosure contemplates that the thickness of the pressure sensing mat can be uniformly minimized (e.g., to a few millimeters) by using coplanar electrodes 108 and conductive ink 110, which reduces the influence the pressure sensing mat has on the user.

[0042] As described above, geometrical parameters of the coplanar electrodes can be selected to obtain a desired level of pressure sensing sensitivity. For example, the sensor area depicts the largest pressure at a single point (force) exerted onto/by the user's anatomy which resides within, and is in contact with the sensor area. This ultimately dictates the individual sensor resolution, defined for example, as the certainty which one can identify the exact location that is being sensed/measured. This differs from the sensing resolution which can be defined for example as the certainty with which one can differentiate measured values between two points within the overall sensing area, i.e., how many sensing elements are within the total sensing area and what is their individual sensor resolution. The spacing between opposing electrodes (e.g., the elongate fingers of the coplanar electrodes) dictates sensor sensitivity. This is because the resistance is a function of length which in this case is the shortest distance between the opposing electrode fingers, which differ in potential. The larger this characteristic distance is the larger the resistance will be and the less a user can influence the change in this resistance. The area of the individual finger (e.g., the elongate fingers of the coplanar electrodes) dictates the sensing range (difference between largest and smallest measurable force). This is because the larger the finger area, the higher the finger resistance will be and creates a higher base resistance. The higher a base resistance in the sensor network is, the less a change in the resistance will affect the overall measurement.

[0043] The coplanar electrodes 108 can be electrically connected to each other by the conductive ink 110 having variable resistivity. For example, the conductive ink 110 can be printed on, or otherwise applied to, the flexible substrate 106 to provide an electrical connection between the coplanar electrodes 108. The conductive ink 110 can have variable resistivity such that the resistance of the conductive ink 110 varies according to the force applied thereto. For example, the conductive ink 110 can exhibit relatively larger resistance in response to lesser applied forces (or lack of applied force) and relatively smaller resistance in response to greater applied forces. In other words, the resistance of the conductive ink 110 can decrease with increasing amounts of applied force. Optionally, the conductive ink 110 can be a carbon based conductive ink. Carbon based conductive ink can significantly increase the full-scale range of the sensor pads 102, for example as compared to using other variable resistive materials such as pressure sensitive conductive sheets such as LINQSTAT from Caplinq Corp. of Fleemskerk, The Netherlands or VELOSTAT from 3M Corp. of Maplewood, MN. It should be understood that carbon based conductive ink is provided only as an example. This disclosure contemplates using other types of conductive ink. Conductive inks are well known in the art and are therefore not described in further detail below. The sensor pads 102 described herein have a number of advantages over conventional sensing technologies including, but not limited to, increased durability and flexibility, which facilitate the ability of the sensor pads 102 to match the contours of the individual's body, for example when the system is incorporated into a mobility assistance device. These advantages are due, at least in part, to the use of flexible materials and/or conductive traces and/or conductive inks.

[0044] The sensor pads 102 can be operably coupled to the controller 104. The sensor pads 102 and the controller 104 can be coupled through one or more communication links.

Additionally, the controller 104 can be operably coupled to a remote computer (e.g., mobile computing device, tablet computer, laptop computer, and/or other computing device) through one or more communication links. This disclosure contemplates the communication links are any suitable communication link. For example, a communication link may be implemented by any medium that facilitates data exchange between the sensor pads 102 and the controller 104 (and optionally a remote computer) including, but not limited to, wired, wireless and optical links.

Example communication links include, but are not limited to, a LAN, a WAN, a MAN, Ethernet, the Internet, or any other wired or wireless link such as WiFi, WiMax, 3G or 4G.

[0045] Optionally, as shown in Fig. 1, electrical traces 112 can extend from each of the sensor pads 102 to an electrical connector 114 that interfaces with the controller 104. In some implementations, the electrical traces 112 can be formed of conductive ink. In some

implementations, the electrical traces 112 can optionally be conductive ink such as a silver-based conductive ink, for example. It should be understood that silver-based conductive ink is provided only as an example and that the electrical traces 112 can be made of other materials. The use of conductive ink (as opposed to wires) to connect the sensor pads 102 to the controller 104 increases durability of the sensor pads 102, which facilitates the ability of the sensor pads 102 to match the contours of the individual's body. Optionally, in some implementations, the controller 104 can be operably coupled to the remote computer using a wireless communication link such as WiFi or Bluetooth (i.e., for lower power). In addition, the controller 104 can include a processor and memory (e.g., at least the basic configuration of computing device 300 of Fig. 3). Another example controller is shown in Fig. 12. As described herein, the controller 104 can be configured to receive a respective signal from each of the sensor pads 102, and characterize activity of the individual based on the respective signals.

[0046] Optionally, in some implementations, the controller 104 can further include a potentiometer configured to adjust a sensitivity of at least one of the sensor pads 102. Optionally, a potentiometer can be provided for each of the sensor pads 102 such that the respective sensitivity of each of the sensor pads 102 can be individually controlled. The individual can adjust the resistance of the potentiometer(s) to adjust the sensitivity of the sensor pads 102. This can optionally be accomplished using an application (e.g., SitSmart app of Fig. 14) running on a computing device. The potentiometer can be included in the Signal Conditioning Unit shown in Fig. 20C, for example. Alternatively or additionally, the controller 104 can optionally further include a multiplexer (e.g., a complementary metal-oxide-semiconductor (CMOS) multiplexer) configured to individually select each of the sensor pads 102 for measurement. Using a multiplexer, each of the sensor pads 102 can be individually sampled, and the respective signal provided to the processor. The multiplexer also eliminates crosstalk between the sensor pads 102 since the sensor pads 102 are sampled one at a time. Including a multiplexer eliminates the need to have a digital potentiometer for each sensor pad as the processor unit can store the preset values of each sensor pad. Then, when switching between sensor pads, it is also possible to switch the potentiometer values. In this sense, it is possible to individually calibrate each sensor pad. The multiplexer can be included in the Signal Conditioning Unit shown in Fig. 20C, for example. Alternatively or additionally, the system can optionally further include a rechargeable battery such as a lithium phosphorous oxy-nitride (UPON) battery. Optionally, the controller 104 can include a power management module (e.g., the Power

Management Unit shown in Fig. 20B) to control the state of the battery charge. [0047] As described above, the controller 104 can be configured to receive a respective signal from each of the sensor pads 102, and characterize activity of the individual based on the respective signals. The step of characterizing activity of the individual based on the respective signals can include predicting changes in a postural position of the individual. For example, the postural position of the individual can be a neutral posture, an anterior pelvic tilt posture, a posterior pelvic tilt posture, a pelvic rotation posture, a pelvic obliquity posture, a forward lean posture, or a side lean posture. In some implementations, changes in a postural position of the individual can be predicted by applying a moving average filter to the respective signals, and detecting a percentage change in one or more of the respective signals relative to a threshold level. Alternatively or additionally, the controller 104 can be further configured to measure frequency or duration of the changes in the postural position of the individual. Alternatively or additionally, the controller 104 can be further configured to generate display data representing a respective relative pressure applied to each of the sensor pads 102. This disclosure contemplates that the display data can be transmitted from the controller 104 to a remote computer (e.g., mobile phone, tablet computer, laptop computer, or other computing device) over one or more communication links for display on a display device.

[0048] It should be appreciated that the logical operations described herein with respect to the various figures may be implemented (1) as a sequence of computer implemented acts or program modules (i.e., software) running on a computing device (e.g., the computing device described in Fig. 3), (2) as interconnected machine logic circuits or circuit modules (i.e., hardware) within the computing device and/or (3) a combination of software and hardware of the computing device. Thus, the logical operations discussed herein are not limited to any specific combination of hardware and software. The implementation is a matter of choice dependent on the performance and other requirements of the computing device. Accordingly, the logical operations described herein are referred to variously as operations, structural devices, acts, or modules. These operations, structural devices, acts and modules may be implemented in software, in firmware, in special purpose digital logic, and any combination thereof. It should also be appreciated that more or fewer operations may be performed than shown in the figures and described herein. These operations may also be performed in a different order than those described herein.

[0049] Referring to Fig. 3, an example computing device 300 upon which embodiments of the invention may be implemented is illustrated. It should be understood that the example computing device 300 is only one example of a suitable computing environment upon which embodiments of the invention may be implemented. Optionally, the computing device 300 can be a well-known computing system including, but not limited to, personal computers, servers, handheld or laptop devices, multiprocessor systems, microprocessor-based systems, network personal computers (PCs), minicomputers, mainframe computers, embedded systems, and/or distributed computing environments including a plurality of any of the above systems or devices. Distributed computing environments enable remote computing devices, which are connected to a

communication network or other data transmission medium, to perform various tasks. In the distributed computing environment, the program modules, applications, and other data may be stored on local and/or remote computer storage media.

[0050] In its most basic configuration, computing device 300 typically includes at least one processing unit 306 and system memory 304. Depending on the exact configuration and type of computing device, system memory 304 may be volatile (such as random access memory (RAM)), non-volatile (such as read-only memory (ROM), flash memory, etc.), or some combination of the two. This most basic configuration is illustrated in Fig. 3 by dashed line 302. The processing unit 306 may be a standard programmable processor that performs arithmetic and logic operations necessary for operation of the computing device 300. The computing device 300 may also include a bus or other communication mechanism for communicating information among various components of the computing device 300.

[0051] Computing device 300 may have additional features/functionality. For example, computing device 300 may include additional storage such as removable storage 308 and non- removable storage 310 including, but not limited to, magnetic or optical disks or tapes. Computing device 300 may also contain network connection(s) 316 that allow the device to communicate with other devices. Computing device 300 may also have input device(s) 314 such as a keyboard, mouse, touch screen, etc. Output device(s) 312 such as a display, speakers, printer, etc. may also be included. The additional devices may be connected to the bus in order to facilitate communication of data among the components of the computing device 300. All these devices are well known in the art and need not be discussed at length here.

[0052] The processing unit 306 may be configured to execute program code encoded in tangible, computer-readable media. Tangible, computer-readable media refers to any media that is capable of providing data that causes the computing device 300 (i.e., a machine) to operate in a particular fashion. Various computer-readable media may be utilized to provide instructions to the processing unit 306 for execution. Example tangible, computer-readable media may include, but is not limited to, volatile media, non-volatile media, removable media and non-removable media implemented in any method or technology for storage of information such as computer readable instructions, data structures, program modules or other data. System memory 304, removable storage 308, and non-removable storage 310 are all examples of tangible, computer storage media. Example tangible, computer-readable recording media include, but are not limited to, an integrated circuit (e.g., field-programmable gate array or application-specific 1C), a hard disk, an optical disk, a magneto-optical disk, a floppy disk, a magnetic tape, a holographic storage medium, a solid-state device, RAM, ROM, electrically erasable program read-only memory (EEPROM), flash memory or other memory technology, CD-ROM, digital versatile disks (DVD) or other optical storage, magnetic cassettes, magnetic tape, magnetic disk storage or other magnetic storage devices.

[0053] In an example implementation, the processing unit 306 may execute program code stored in the system memory 304. For example, the bus may carry data to the system memory

304, from which the processing unit 306 receives and executes instructions. The data received by the system memory 304 may optionally be stored on the removable storage 308 or the non removable storage 310 before or after execution by the processing unit 306.

[0054] It should be understood that the various techniques described herein may be implemented in connection with hardware or software or, where appropriate, with a combination thereof. Thus, the methods and apparatuses of the presently disclosed subject matter, or certain aspects or portions thereof, may take the form of program code (i.e., instructions) embodied in tangible media, such as floppy diskettes, CD-ROMs, hard drives, or any other machine-readable storage medium wherein, when the program code is loaded into and executed by a machine, such as a computing device, the machine becomes an apparatus for practicing the presently disclosed subject matter. In the case of program code execution on programmable computers, the computing device generally includes a processor, a storage medium readable by the processor (including volatile and non-volatile memory and/or storage elements), at least one input device, and at least one output device. One or more programs may implement or utilize the processes described in connection with the presently disclosed subject matter, e.g., through the use of an application programming interface (API), reusable controls, or the like. Such programs may be implemented in a high level procedural or object-oriented programming language to communicate with a computer system. However, the program(s) can be implemented in assembly or machine language, if desired. In any case, the language may be a compiled or interpreted language and it may be combined with hardware implementations.

[0055] Example

[0056] An example activity monitoring system for an individual using a wheelchair or scooter is described below. The activity monitoring system is referred to as the "SitSmart." The SitSmart demonstrates the ability to utilize a pressure measurement mat (e.g., sensor pads 102 of Fig. 1), a controller (e.g., controller 104 of Fig. 1), a user interface (e.g., SitSmart App of Fig. 14), and data analysis algorithms to monitor and characterize the activity of seated individuals, specifically individuals who utilize a wheelchair or scooter. The SitSmart has applications in consumer and medical markets, with the ultimate goal of improving the quality of life of individuals with disabilities. SitSmart has advantages over other products currently on the market in terms of its durability, reliability of sensor pads, cost, and algorithms. Current pressure mats used in healthcare applications rely on high resolution mats, are designed for use over short periods of time (e.g., <60 minutes) in the medical setting, and do not measure an individual's overall activity. SitSmart is designed as an activity monitor for use over long periods of time in the community setting.

Furthermore, unlike current pressure mats, SitSmart is designed to provide real-time feedback to the individual using a wheelchair or scooter. SitSmart provides a platform for adding additional activity monitors specifically focused on individual with mobility related disabilities. The goal of the system is to provide real-time feedback in order to improve the quality of life of individuals with mobility related disabilities.

[0057] SitSmart's data analysis algorithm can include a calibration phase in order to characterize the individual's postural positions, as well as the individual's pressure relieving movements, when using the seating system. The postural positions include the neutral (or baseline) posture, anterior and posterior pelvic tilt postures, a pelvic rotation posture, a pelvic obliquity posture, and forward and side lean postures. The pressure relieving movements can be performed manually (e.g. push-up or side lean) or via the power seating system (e.g. tilt recline). Some of the postural and pressure relieving positions can be the same, as some individuals use forward and side lean postures to perform activities of daily living and to perform a pressure relief. Following the calibration phase, the data analysis algorithm measures the frequency and duration of the postural changes and pressure relieving movements in order to quantify an individual's activity while seated in a wheelchair or scooter.

[0058] The SitSmart began as a prototype pressure sensing mat that used neoprene as a substrate and conductive string for circuit traces. The force sensitive resistor (FSR) material used to register the pressure applied to each sensing area was Velostat which is a polymer impregnated with carbon black. As described herein, other FSR materials can be used including, but not limited to, Linqstat. This design provided evidence that an activity monitoring system could be made for an affordable price for the average consumer. This design, however, lacked key characteristics, specifically durability, consistency, and transient response. The original SitSmart prototype is shown in Fig. 4.

[0059] Building on the original SitSmart prototype, a new concept for sensing was implemented which produced a more robust product. The goal was to re-evaluate the design and the pressure sensing characteristics in order to increase the potential for commercialization. The sensing concept chosen was based on the principle of coplanar electrodes connected by a force sensitive material.

[0060] As described herein, the SitSmart (e.g., the activity monitoring system) can include a plurality of coplanar electrodes (e.g., coplanar electrodes 108 of Fig. 1). The coplanar electrodes can be single point sensors, which are capable of sensing a pressure or force in a small region of space and have a single output. Common structures for single point sensors are parallel plate electrodes, fringe electrodes, and coplanar electrodes. The parallel plate electrode configuration produces capacitive characteristics, while the fringe electrode configuration produces non-uniform resistivity. Both the parallel plate electrode and the fringe electrode configurations require an extra process of alignment between the two electrode layers resulting in larger uncertainty and reduced predictability. On the other hand, an advantageous aspect of the coplanar electrode structure is that both electrodes (e.g., coplanar electrodes of Figs. 1, 2A, and 2B) can be attached to the same substrate, which saves space, cost, and manufacturing complexity.

[0061] Optimizing the resistance of the coplanar electrodes to allow full resolution of the sensing material is a component to the ability to register pressure. As resistance is the inverse of conductance, geometrical parameters of the coplanar electrodes are related to performance of the sensing material. The key geometrical parameters are described in the following equation.

[0062] — = WL -

RVR S [0063] s = electrical conductivity —J

[0064] WL = surface area of planar electrodes (m ² )

[0065] 5 = distance between electrodes (m)

[0066] The electrode design determines the characteristics of the sensor's robustness in terms of capacitance and resistivity. More commonly referred to as the impedance, the combination of the two properties dictates the response characteristic under a transient input (Force). The impedance is as follows:

[0068] Where N is the number of elongate fingers, L is the length of the elongate fingers, and W is the width of the elongate fingers (e.g., see Figs. 2A-2B).

[0069] Issues of durability, consistency, and transient response of the original SitSmart prototype were addressed. For example, the circuitry (e.g., flexible substrate 106, coplanar electrodes 108, conductive ink 110, etc. of Fig. 1) can be laminated between two layers of Kapton (e.g., thin sheets of polymer). In other words, the pressure sensing mat and/or the sensor pads can be hermetically sealed. Therefore, the sensor pads can withstand shear forces that may otherwise peel off the adhered traces. Additionally, the lamination allows for the possibility of a water proof seal. Additionally, the conductive ink (e.g., ink used for electrical traces such as electrical traces 112 of Fig. 1) characteristics were improved by using a carbon filler, aqueous based solution and therefore is removable with water. This was done in order to survive prolonged agitation such as bending, creasing, compression and tension. The SitSmart prototype including coplanar electrodes and Kapton sealing layers is shown in Fig. 5. [0070] In some implementations, the conductive ink (e.g., ink used for electrical traces such as electrical traces 112 of Fig. 1) can be a silver filler, solvent based solution. This consequently increases the adhesion and conductivity of the conductive traces. The silver filler, solvent based ink significantly increased the robustness of the sensor pads which improves the ability of the sensor pads to withstand conditions encountered as a consumer based product. Another SitSmart prototype including coplanar electrodes and Kapton sealing layers is shown in Fig. 6. The SitSmart prototype of Fig. 6 was able to withstand substantial testing procedures over several weeks.

Transient properties were vastly improved as the time constant for the system was orders of magnitude faster than that of the response time of a human subject. Over the multi-week period of testing, degradation was noticed in the sensitivity of the FSR material. This intrinsic property of the sensing material ultimately led to an enhancement in the signal processing hardware.

[0071] The SitSmart can be configured for standard connectivity for improved reliability, durability and ease of connecting the pressure sensing mat to the electronics. An electrical connector (e.g., connector 114 of Fig. 1) that interfaces with a standard 14 pin ribbon cable adapter can be used to connect the sensor pads to a controller (e.g., controller 104 of Fig. 1). This step provides the capability to extract the signals from the sensor pads in a form that aligns with the standard industry practice. It also introduces a thicker substrate for a more durable product. An adhesive spray was added between layers to re-enforce the contact between traces and Linqstat, and increase the resistance to water damage. Another SitSmart prototype configured for standard connectivity is shown in Fig. 7. The SitSmart prototype of Fig. 7 was able to produce consistent characteristics over a series of manufactured mats. The SitSmart prototype of Fig. 7 provided all the traits that were lacking with the original SitSmart prototype of Fig. 1.

[0072] Referring again to Fig. 1, an activity monitoring system (e.g., another SitSmart prototype) is shown. The system of Fig. 1 is printed with conductive ink (e.g., coplanar electrodes 108, electrical traces 112 of Fig. 1) onto a flexible substrate (e.g., flexible substrate 106 of Fig. 1).

Focus for the system of Fig. 1 lies in the repeatability, manufacturability, and overall product cost, which are the fundamental traits for the successful commercialization of a consumer product. A run of ten prototypes demonstrated that tight tolerances can be achieved with printed electronics technology. The FSR portion of the sensor pads (e.g., sensor pads 102 of Fig. 1) was implemented with variable resistive carbon based ink in Fig. 1, as opposed to Velostat or Linqstat in Figs. 4-7. This enhancement vastly increases the full-scale range of the SitSmart, allowing the inclusion of an even greater portion of the population in terms of anthropometric measurements. In large scale, the cost of the SitSmart is incredibly affordable and provides the ergonomic properties desired for a consumer and the functional traits required by healthcare technology.

[0073] The controller for the original SitSmart prototype (Fig. 4) was an ensemble of buffer amplifiers, an ARDUINO MICRO microcontroller, and IK resistors along with an assortment of wires. The controller for the original SitSmart prototype of Fig. 4 is shown in Fig. 8. The buffer amplifiers are implemented to allow impedance matching between the high impedance of the SitSmart and the high impedance of the analog input of the microcontroller. The principle of sensor circuitry is that the output impedance of a sensor should be much lower than the input impedance of the analog-to-digital converter (ADC) unit. The buffer introduces an exceedingly high impedance at the input of the device and a very low output impedance. This allows for the impedance to be matched, all the while maintaining the original signal. The resistors allow for a voltage divider to be implemented so that the change in voltage can be measured. As a result, the change in force applied to the sensor is proportional to the change in voltage. The main disadvantage of this technique is that sensitivity is dependent on the ratio of the set resistor value, R _d , and the sensor resistor value, P _S ( ). Since the resitance of the sensor varies nonlinearly with pressure, the sensitivity is non constant as pressure varies. This can be seen as the relationship of sensitivity, is dependent on

the ratio of ^Rs ^ and R _S (P ) is porportional to— ln(P). Therefore, the trick is to choose R _d to be as

Rd

close as possible to R _S (P ) at the maximum pressure. dV _A R _S (P)

- oc - dP R _d

R _S (P ) oc— ln(P)

[0074] The controller for the SitSmart prototype of Fig. 5 is shown in Fig. 9. On a circuitry level this controller is identical to the controller of Fig. 8. The essential upgrade lies in securing all the components into a portable module. This allows then two separate products to be engineered, the SitSmart and the SitSmart Controller. As the SitSmart is improved and enhanced so is the controller to match and even improve the performance of the sensor pads. The objective in each revision of the controller is to improve the robustness so that it may accommodate the changing characteristics of the individual sensor pads as they age. The controller is engineered over several revisions to solve the intrinsic issues discovered in the design cycle of the SitSmart. These include the degradation of the signal over long periods of continued use, communication to the user for essential feedback, and power management.

[0075] The controller for the SitSmart prototype of Fig. 6 is shown in Fig. 10. This controller is reengineered to integrate the controller with the SitSmart. As a first attempt to remove all wires, the connector was designed to attach directly to the sensor pads. To do so, a 3D printed mold was used for securing the traces from the mat to the controller's ADC unit. The traces were sent to a header allowing the controller to be modularly attached. This allows for different boards to be tested with the mat. It also enables a quick redesign cycle with minimum cost without impeding the quality of the signal. This controller also included an addition memory device to enable remote logging for testing purposes.

[0076] The controller for the SitSmart prototype of Fig. 7 is shown in Fig. 11. This is a giant leap forward in the design cycle of the SitSmart Controller. It was redesigned with electronic computer aided design (ECAD) software to allow a printed circuit board (PCB) module to be ordered and assembled. This controller scales down the controller by four-fold, and enables the repeatable manufacturing of the controller, a crucial step in the commercialization process. The circuitry again is very similar to the controllers of Figs. 8-10 with the only difference being in the adjustment of the resistor values and the surface mount technology (SMT) connector.

[0077] The controller for use with the activity monitoring system of Fig. 1 is shown in Fig. 12. This controller brings the powerhouse features of a power management system (e.g., Fig. 20B), signal condition system (e.g., Fig. 20C), a memory system (e.g., Fig. 20A), and an upgraded microcontroller (e.g., Fig. 20A) that features a handful of wireless communication capabilities.

Robustness is added by including digital potentiometers to control the sensitivity of each sensor. The controller also includes a complimentary metal-oxide-semiconductor (CMOS) multiplexer which cuts the required buffer amps down from eight to just one. The multiplexer also eliminates any crosstalk between sensors as it samples just one at a time with a switching time of a few hundred

nanoseconds. The power management system includes a recharging module for a 3.3V UPON battery, eliminating the need to hookup to an external power source. The Red Bear DUO includes WIFI, Bluetooth and Cloud based communication. The controller also allows over the air updates to a network of controllers.

[0078] The next step in introducing the product to market is the successful transition from a research tool to a consumer product. Of course, there are numerous potential access points along this route, such as health care data and network accessible data (telehealth). The main focus in the current design cycle is to present the information in such a way that activity can be quantified and interpreted. Figs. 13A and 13B illustrate graphical representations of the layout of the sensor pads of the activity monitoring system of Fig. 1. Figs. 13A and 13B provide a visualization of signals from a non-engaged (Fig. 13A) and fully engaged (Fig. 13B) sensor pads. The vertical axis represents the relative pressure being exerted onto the sensor area (e.g., each of the sensor pads). The units are in terms of the percentage of the maximum measurable value. There is no need to calibrate the sensor pads in units of pressure since the full scale range accommodates the entirety of a person's mass. This allows the system to then measure the change in voltage thereby tracking the change in activity. [0079] An example SitSmart App user interface is shown in Fig. 14. The SitSmart app was created to demonstrate the ability to communicate wirelessly. The app allows the user to control the sensitivity by adjusting the set resistance within the voltage divider. It also allows the user to switch between sensors and to view two separate sensors' responses simultaneously. The app

demonstrates the true robustness of the controller as it communicates through Bluetooth Low Energy. It also allows the update of programs wirelessly and mass network updates.

[0080] The data collected from the SitSmart is shown in Figs. 15-19. The process of modeling the transient response begins with fitting a first order system equation to the step response of the sensor pads. Once the parameters are equated, the analytical model can be accessed and tested. This all leads to the ability to quantify the sensitivity of the response on different surfaces. Characterizing these responses, one can then develop a predicative algorithm to recognize and track different activities.

[0081] The prediction is based off a moving average algorithm. It introduces a delay as it windows the signal. Then it recognizes the percentage change in the signal, registering it if this characteristic rises above a certain threshold. The frequency of the change in posture for the individual can be tracked and presented back to the user.

[0082] Although the subject matter has been described in language specific to structural features and/or methodological acts, it is to be understood that the subject matter defined in the appended claims is not necessarily limited to the specific features or acts described above. Rather, the specific features and acts described above are disclosed as example forms of implementing the claims.