Background

[0001] It is known to measure or monitor biometric characteristics or vital signs of a person, such as blood oxygen saturation level or pulse rate, to assess the general health of that person. The devices used for monitoring vital signs in a hospital environment are typically relatively bulky and uncomfortable and therefore may not be suitable for use in other environments, such as in space.

[0002] It is desirable to find a more comfortable solution for users, such as astronauts, to log medical data, such as data relating to biometric characteristics of a user, for example for a prolonged period of time, without impeding day to day activities of the user.

Brief Description of the Drawings

[0003] Further features will become apparent from the following description, given by way of example only, which is made with reference to the accompanying drawings.

[0004] FIG. 1 shows schematically an earpiece according to an example;

[0005] FIG. 2 shows the earpiece of FIG. 1 mounted behind an ear;

[0006] FIG. 3 shows a further view of the earpiece of FIG. 1 mounted behind an ear;

[0007] FIGS. 4a and 4b show schematically an example circuit for use with an earpiece;

[0008] FIG. 5 shows schematically an example printed circuit board (PCB) for use with an earpiece;

[0009] FIGS. 6a, 6b, 6c and 6b show schematically further examples of an earpiece; and

[0010] FIG. 7 shows schematically an example of a monitoring system;

[0011] FIG. 8 shows schematically an example sensing circuit for use with an earpiece;

[0012] FIG. 9 shows schematically an example arrangement of radiation sources and radiation detectors for use with an earpiece; and

[0013] FIG. 10 shows schematically the location of example circuitry within an example earpiece.

Detailed Description

[0014] Details of the earpiece and monitoring system according to examples will become apparent from the following description, with reference to the figures. In this description, for the purpose of explanation, numerous specific details of certain examples are set forth. Reference in the specification to "an example" or similar language means that a particular feature, structure or characteristic described in connection with the example is included in at least that one example, but not necessarily in other examples. It should further be noted that certain examples are described schematically with certain features omitted and/or necessarily simplified for ease of explanation and understanding of the concepts underlying the examples.

[0015] The earpiece and the monitoring system described herein were inspired by the current limitations of wearable space technologies. Cumbersome clothing not only has the problem of interfering with daily movements, but is also susceptible to solar radiation when microchips are incorporated into fabrics. When researching the lives of astronauts, the inventors surprisingly realised that there was one area of the body that had been ignored by designers: that imperceptibly small space behind the concha of the ear and the neck.

[0016] Accordingly, examples described herein include an earpiece mountable behind an ear of a user. The earpiece includes a casing and, disposed within the casing, a power source and circuitry for measuring a biometric characteristic of the user using reflectance pulse oximetry. The power source is arranged to supply power to the circuitry.

[0017] The earpiece in such examples can be mounted behind the concha of the ear, so that the earpiece lies between the back or rear side of the ear and the head of the user. With appropriate attachment, this allows the earpiece to be worn comfortably for long periods of time, for example allowing real time monitoring of a biometric characteristic of a user, such as a blood oxygen saturation level, a pulse rate or a respiratory rate, continuously for hours, days, weeks or months at a time. This can be beneficial in a space environment, in which it is desirable to constantly monitor the health of astronauts. Furthermore, as the earpiece is mountable behind the ear of the user, the earpiece is protected between the ear and the head of the user and thus may remain secure throughout a variety of activities of the user such as during exercise, while sleeping or even during a spacewalk. In addition, the mounting of the earpiece behind the ear of the user means that the user can wear in-ear headphone buds, glasses, over- ear headphones or in-ear hearing aids at the same time as the earpiece. This means that the user can wear the earpiece without altering their usual activities, such as listening to music or receiving commands via headphones.

[0018] Moreover, the head benefits from central blood circulation, which allows a more reliable measurement of biometric characteristics, such as blood oxygen saturation level, pulse rate or respiratory rate, to be taken than other regions of the body. For example, in shock, the body shuts down the blood supply to the hands, making measurements of biometric characteristics based on a pulse oximetry on the finger or wrist less reliable than measurements taken behind the ear. Accordingly, measurements taken by the earpiece in examples described herein may be more accurate than with other devices that take measurements from different body locations. Measurements taken by the earpiece may also suffer from lower noise than measurements taken elsewhere on the body because humans naturally keep their heads in a relatively stable or constant position, to protect the brain and to ensure a relatively stable field of view. Hence, there may be reduced noise due to motion artifacts in data obtained by the earpiece than in data taken from a device located on the hand or wrist for example, which tend to move to a much greater extent than the head.

[0019] Further examples relate to a monitoring system including an earpiece mountable behind an ear of a user. The earpiece may be similar to that described above and may include a casing and, disposed within the casing, a power source and circuitry for measuring a biometric characteristic of the user using reflectance pulse oximetry. The power source of the earpiece is arranged to supply power to the circuitry. The monitoring system also includes a charging apparatus for charging the power source of the biometric monitoring earpiece. These further examples may therefore allow an earpiece to be charged, for example so that the earpiece can be worn independently of the charging apparatus. This provides further flexibility for the monitoring system and for example allows the earpiece to be worn in situations in which mains power may be absent or intermittent, such as in space.

[0020] In some examples, the charging apparatus may be arranged to wirelessly charge the power source of the earpiece, allowing for easy recharging of the earpiece, for example without having to take the earpiece off. This may simplify charging of the earpiece in space, as astronauts may be able to charge the earpiece without having to take off helmets or other space apparel.

[0021] The monitoring system may include a gas sensing device arranged to measure a proportion of a predetermined gas, such as carbon dioxide, in a gas sample incident on the gas sensing device. The gas sensing device may include the charging apparatus, to reduce the number of separate components of the monitoring system. The charging apparatus may for example be a wearable charging apparatus, allowing further portability, so that the earpiece may be charged during normal day-to-day activities of the user, without the user having to go to a particular location for charging of the earpiece.

[0022] To put the examples described herein into context, the benefits of a particular example of a monitoring system with an earpiece, a charging apparatus arranged to wirelessly charge the power source of the earpiece and the gas sensing device including the charging apparatus will first be described in section 1 below, before further examples are described with reference to the figures in section 2. As will be appreciated, the example of section 1 is merely illustrative and further examples are envisaged, such as the examples of section 2.

1. Monitoring system example

[0023] In this particular example, the monitoring system includes a vital signs monitor and carbon dioxide alarm designed to be worn constantly by astronauts. It detects specific levels of gas in the air and oxygen levels in the blood. In space, this solves the problem of alerting astronauts to carbon dioxide pockets. It also gives researchers an accurate picture of biometrics. Low power, internet of things technology enables a pulse oximeter, wirelessly rechargeable battery and Bluetooth transmitter to be fitted in the earpiece. A mission patch contains the carbon dioxide detector and transmits wireless power to the earpiece. Different mission patches will detect different gases, for example in the military and emergency services, mountaineering, tunnels and mines. In hospitals, the earpiece on its own can be used to gather vitals for all patients. This example monitoring system is a life-saver for wearers and those who benefit from the research it enables.

[0024] The example monitoring system is designed for space: it provides comfortable, unobtrusive biomedical and CO2 monitoring of vitals in a package designed to last in space. The monitoring system includes a vital signs monitor, with earthbound applications in medicine, mining and tunneling industries, mountaineering, and the armed forces.

[0025] The example monitoring system of carbon dioxide (CO2) monitor patch and earpiece acts as a lifeline to the wearer, simultaneously monitoring their heart rate, blood oxygen, and atmospheric CO2 levels. This allows the issue of CO2 pocket build ups within spacecraft to be addressed, for example. The example monitoring system has an audible danger threshold alarm to alert the wearer when they need to head back to safety. Data is automatically transferred by Bluetooth Low Energy to iOS and Android apps or even hospital eHealth wardware using the industry-standard Bluetooth Pulse Oximetry Profile. [0026] The CO2 monitor patch contains the CO2 monitor and batteries that provide wireless charging power to the earpiece as well as sending data of CO2 levels to the monitor hardware. The patch may therefore be considered to be a charging apparatus for charging a power source of a biometric monitoring device such as the earpiece. The patch in examples has a power source, such as wireless power source, and a datalink with the earpiece, which may be a wireless datalink. A suitable sensor for use as a CO2 monitor is the K-30 sensor, available from C02Meter, 131 Business Center Drive, Ormond Beach, FL 32174 USA.

[0027] The earpiece contains the blood oxygenation and heart rate monitor and transmits those body vital signs to the monitor hardware. The earpiece has battery capacity to run for over an hour or longer away from the CO2 monitor patch that charges it. The earpiece is for example a biometric monitoring device.

[0028] During the fast-paced ergonomics design process during the design of the example monitoring system, one of the inventors had a panic about the loss of one of the key prototypes only to realise that they had been wearing it for the previous 6 hours underneath their headphones. A testament to the non-intrusive wearability of the earpiece and the advantage of anchoring technologies to this part of the body.

[0029] The benefits of this example monitoring system mark it out as the future of wearable tech vital signs monitoring. It is unobtrusive and non-invasive, allowing the wearer to change clothes, sleep undisturbed, and put headphones over it without the worry of it catching onto surrounding items. It analyses large data sets meaning that as well as detecting problems in ventilation systems, it can also help to fix them by supplying feedback about problem areas. The ability to gain continuous blood oxygen and heart rate data from individuals in space provides other research benefits, allowing changes to human physiology in space to be better monitored and planning for long duration spaceflight to be improved. In addition, its hard case may protect the delicate microchips within from solar radiation. This can be beneficial for use of the example monitoring system in space.

[0030] The example monitoring system is primarily designed for use on long-haul space missions, aboard space stations, and for commercial use in space hotels. As well as this, the example monitoring system has a bounty of life-saving earth-bound applications. Hazardous gases, such as CO2 or other gases, remain a huge problem for mining industries and tunneling, and the introduction of the example monitoring system provides a solution for the reduction of casualties. Use in hospitals offers the ability for doctors to monitor whole wards of patients constantly, allowing them the opportunity to respond to critical warning signs earlier; this is especially critical for cardiac arrests, strokes and Intensive Care Units. Mountaineers require blood oxygen readings regularly when facing the pitfalls of changing altitude levels. Military applications in war- zones are vast, counteracting chemical warfare as well as keeping tabs on soldiers' vital signs.

[0031] To ensure that the aesthetic design ambitions were realistic, the inventors designed the circuitry required by the device to allow them to accurately assess the space requirements needed.

[0032] From the start the inventors realised that battery size and capacity would be one of the biggest hurdles to overcome to make the device useful and hassle-free for users. As one of the priorities for the inventors was to minimise the mass that needed to be placed on a user's ear, the inventors made the decision to sacrifice battery capacity and install a wireless charging system, allowing the system to have almost continuous power supplied from an easily accessible source. This system allows the primary device power to be supplied externally, but also provides a small battery to act as a buffer, ensuring continuous data collection and transmission is maintained. The battery is for example a power source arranged to supply power to circuitry arranged to measure a biometric characteristic of a user, such as the circuitry described and illustrated in the figures below. A suitable power source for the earpiece is a V250H battery, available from VARTA Microbattery GmbH, DaimlerstraBe 1, D-73479 EUwangen, Germany, with a 240 miUiampere hour (mAh) capacity. The V250H battery for example allows the earpiece to operate independently of the patch for a period of time. The Appendix provides calculations of the estimated charging time of the power source of the earpiece according to this particular example and conservative estimates for the amount of time the earpiece would be able to operate using its power source alone, for example using battery power when disconnected from a further, for example wireless, power source such as a power source provided by the charging apparatus described above.

[0033] To further minimise the size of the ear-based unit the inventors installed a combined Bluetooth and processor system on chip. To measure heart rate and SO2 (oxygen saturation, for example the percentage of haemoglobin which is fully combined with oxygen) levels, the chip (for example a Nordic Semiconductor nRF52832) pulses an infrared light emitting diode (IR LED) into the blood vessels behind the wearer's ear. The reflected signals from this diode are then picked up by an IR detector, where changes in light intensity are converted to a varying voltage signal. This signal is then amplified by an Op-amp, operating in non-inverting amplification mode, and fed into an input on the nRF52831. The signal is sampled by the nRF52831 and temporarily stored in memory before being transferred via BLE (Bluetooth Low Energy) to the user's smartphone or to central medical server. An example of circuitry for use with this particular example monitoring system is provided in FIGS. 4a, 4b and 5.

2. Description of Figures

[0034] FIG. 1 illustrates schematically an example earpiece 100 in plan view, with some of the internal components visible. Other internal components of the earpiece 100 are omitted, for clarity. The earpiece 100 of FIG. 1 is mountable behind the ear of a user, as described further below with reference to FIGS. 2 and 3. An earpiece is for example an item or article that is designed or otherwise arranged to be attached, applied or supported by the ear. For example, the earpiece may be entirely supported by the ear when mounted behind the ear. In examples, the earpiece is arranged to fit over or contact an external part of the ear, for example the rear of the ear, an upper portion of the ear and a lobe of the ear, without contacting or entering the inner ear or ear canal. In such cases, the earpiece may be supported by an outer portion of the auricle or pinna of the ear and for example may not touch or contact the inner surface of the concha of the ear or the ear canal.

[0035] The earpiece 100 has a casing 102. The casing 102 can be manufactured using additive manufacturing techniques (sometimes referred to as "3D printing"), although other manufacturing techniques are possible. The casing 102 may have a concave surface 104 for correspondence with at least part of a rear surface of the ear corresponding to a concha of the ear. FIG. 1 shows such an example. In FIG. 1, the concave surface 104 of the earpiece 100 has a shape which is similar to or approximately the same as the shape of the rear surface of the ear corresponding to the concha. In some examples, the concave surface 104 may have a predetermined or standard shape to conform with a rear surface of a concha of an average person, for example based on an estimated shape of the concha of the average person. In other examples, though, the concave surface 104 may be user- specific. For example, the rear surface of the ear corresponding to the concha of a particular user may be scanned, using a three- dimensional scanner for example, to obtain data representing a shape of this rear surface for that user. The casing 102 may then be manufactured, for example using 3D printing, to match or conform to the shape of the rear surface of the ear corresponding to the concha, based on the data obtained from the scan. Any suitable material, such as plastic or metal, may be used for the casing 102. The casing 102 may for example be waterproof, so that the internal components of the earpiece 100 do not become damaged due to contact with water or other liquids. The casing 102 may be waterproof up to a depth of 10 metres, for example, allowing the earpiece 100 to be worn in underwater settings as well as in dry environments.

[0036] Disposed within the casing 102, the earpiece 100 includes a power source 106. The power source 106 may be any suitable power source such as one or more batteries. As described above with reference to the particular example monitoring system, a suitable battery is the V250H battery. The power source 106 may be wirelessly chargeable, as will be described further below with reference to FIGS. 4a, 4b and 5. The earpiece 100 also includes, within the casing 102, circuitry for measuring a biometric characteristic of the user, such as blood oxygen saturation level, pulse rate or respiratory rate, using reflectance pulse oximetry. In the example of FIG. 1, the circuitry includes a radiation source and detector for reflectance pulse oximetry, labelled schematically in FIG. 1 with the reference numeral 108. The circuitry in this example also includes a processor 110 such as the Nordic Semiconductor nRF52832 chip, although other processors are possible in other examples. The power source 106 is arranged to supply power to the circuitry. The power source 106, the radiation source and detector 108 and the processor 110 in the example of FIG. 1 are each connected to or form part of a printed circuit board 112, which for example has a trapezoidal shape (as can be seen further in FIG. 5), which allows the printed circuit board 112 to be mounted securely within the casing 102. The connections between the components of the earpiece 100 are not illustrated in FIG. 1, for clarity, but are described further below with reference to FIGS. 4a, 4b and 5.

[0037] The casing 102 may be any suitable shape for containing the electronic components described above, so that the earpiece can function as a biometric monitoring device, for measuring a biometric characteristic of a user for example, and so that the earpiece 100 can be mounted behind the ear of the user. For example, a width of the earpiece 100 may taper towards an end of the earpiece 100. FIG. 1 shows such an example. In FIG. 1, the earpiece 100 tapers from an upper end towards a lower end.

[0038] The earpiece 100 may for example have a first portion and a second portion narrower than the first portion, the power source 106 located in the first portion (which is the wider portion). In such examples, at least part of the circuitry, which in this example includes the radiation source and detector 108 and the processor 110, may be located in the second portion. The power source 106 may be heavier, more massive or larger than the circuitry or than other components of the earpiece 100. For example, the power source 106 may be the most massive and/or the largest of the components of the earpiece 100. By locating the power source 106 in a wider portion, the space or cavity within the casing 102 can be used most effectively, minimising the overall size of the earpiece 100. This can improve the comfort of the earpiece 100 for the user, as slimmer or smaller earpieces 100 may fit behind the ear more comfortably than larger or heavier earpieces.

[0039] The first portion may be between a centre point 114 of the earpiece 100 and a first end 116 of the earpiece 100 and the second portion may be between the centre point 114 and a second end 118 of the earpiece. The first end 116 for example includes the uppermost point of the earpiece 100 with the earpiece 100 orientated for mounting behind the ear of the user and the second end 118 for example includes the lowermost point of the earpiece 100 with the earpiece 100 orientated for mounting behind the ear. For example, the first end 116 of the earpiece 100 or a region of the earpiece 100 including the first end 116 may be configured to be mounted adjacent to, in contact with or facing an upper portion of the ear, for example corresponding with a rear surface of the helix of the ear. Similarly, the second end 118 of the earpiece or a region of the earpiece 100 including the second end 118 may be configured to be mounted adjacent to a lobe of the ear.

[0040] With this arrangement, the first portion may correspond with an upper half of the earpiece 100 and the second portion may correspond with a lower half of the earpiece 100. Thus, the power source 106 may be located in a first half of the earpiece 100 including the first end 116 and at least part of the circuitry, for example the radiation source and detector 108, may be located in a second half of the earpiece 100 including the second end 118. By locating the power source 106 in the first portion or in the first half, the earpiece 100 may be more stable when mounted behind the ear, as will be described further below. For example, a centre of mass of the earpiece 100 may be closer to the first end 116 of the earpiece 100 than the second end of the earpiece 100. This may give the earpiece 100 an asymmetric or top-heavy mass distribution, which may help to anchor the earpiece 100 to the ear when mounted behind the ear.

[0041] In examples such as that of FIG. 1 , the earpiece 100 includes a first attachment element 120 for contacting a first portion of the ear and a second attachment element 122 for contacting a second portion of the ear. The first attachment element 120 may extend from a first end portion 124 of the casing 102 and the second attachment element may extend from a second end portion 126 of the casing 102, opposite to the first end portion 124 of the casing 102. The first end portion 124 and the second end portion 126 may each be any region of the casing that includes one of the extremities of the casing 102. For example, the first end portion 124 may be any section of the casing 102 that includes the upper end of the casing 102 with the casing 102 orientated for mounting on the ear of the user. For example, the first end portion 124 of the casing 102 may include the first end 116 of the earpiece 100. Similarly, the second end portion 118 may be any section of the casing 102 that includes the lower end of the casing 102 with the casing 102 orientated for mounting on the ear of the user, and may include the second end 118 of the earpiece.

[0042] The first attachment element 112 may be configured to contact an upper portion of the ear and the second attachment element 114 may be configured to contact a lower portion of the ear, such as a lobe of the ear. FIG. 1 shows such an example. This is illustrated further in FIGS. 2 and 3.

[0043] FIG. 2 shows the earpiece 100 of FIG. 1 mounted behind an ear 128 and FIG. 3 shows a further view of the earpiece 100 of FIG. 1 mounted behind an ear 128, with some of the internal components of the earpiece 100 shown, to indicate the relative position between the internal components of the earpiece 100 and the ear 128. Some of the labels shown in FIG. 1 are omitted in FIGS. 2 and 3 and the earpiece 100 is illustrated with dashed lines in FIG. 3, for clarity.

[0044] In examples such as FIGS. 2 and 3, the first portion of the ear, which the first attachment element 120 may be configured to contact, includes an upper portion of the ear and the second portion of the ear, which the second attachment element 122 may be configured to contact, includes a lobe of the ear. Thus, the first attachment element 120 and the second attachment element 122 may be configured to affix the upper and lower ends of the casing 102 to the upper and lower portions of the ear, respectively. There may be a gap or space between a free end of the first attachment element 120 (such as the end of the first attachment element 120 that is not in contact with, connected to or does not extend from the casing 102) and a free end of the second attachment element 122. For example, a combination of the first attachment element 120 and the second attachment element 122 may have a length smaller than a height of an average ear, so that the first attachment element 120 and the second attachment element 122 do not touch or overlap each other with the earpiece 100 mounted behind the ear of the user. This may mean that one or both of the first attachment element 120 or the second attachment element 122 do not extend to contact an inner portion of the ear, for example the ear canal. For example, one or both of the first attachment element 120 or the second attachment element 122 may be configured for contact solely with an exterior of the ear of the user. This may improve the comfort of the earpiece 100 compared with attachment elements that intrude into an ear canal of the user.

[0045] The design of one or both of the first attachment element 120 and the second attachment element 122 may also be selected to improve the comfort of the earpiece 100 when mounted behind the ear of the user. For example, the second attachment element may have a shape to cup a lobe of the ear without substantially compressing the lobe. In other words, the second attachment element may be shaped or configured to cradle the lobe without clamping onto the lobe or pinching the lobe. This may be more comfortable than a clip, which may be painful if worn for an extended period of time. For example, a clip typically is a sprung or hinged element with two opposing surfaces or jaws that are biased against each other to compress an object, such as a body part, between the jaws. In contrast, the second attachment element may merely rest on or touch the lobe without applying inward or compressive pressure to the lobe. Thus, this allows the earpiece 100 to be worn for a longer continuous period of time than otherwise. For example, as shown in FIGS. 2 and 3, the second attachment element 122 may be a substantially v-shape or a substantially u-shape, such as a shape which is a v- shape or a u-shape or approximately or recognizably a v-shape or a u-shape without necessarily being a perfect v-shape or u-shape, for example a u-shape or a v-shape within manufacturing tolerances.

[0046] The first attachment element 120 may also or alternatively have a shape to avoid pinching, clamping or other pressure on the ear of the user. For example, the first attachment element 120 may have a shape to hook over an upper portion of the ear, as shown in FIGS. 2 and 3. Such a shape may be a curved shape, which may curve towards and around the upper portion of the ear.

[0047] One or both of the first attachment element 120 and the second attachment element 122 may be reversibly deformable, for example by hand. In other words, the first attachment element 120 and/or the second attachment element 122 may be bendable, mouldable or pliable by hand, to allow the earpiece 100 to be mounted behind the ear of the user. For example, the first attachment element 120 and the second attachment element 122 may each be or include a flexible wire.

[0048] The example earpiece 100 of FIGS. 2 and 3 may be mounted behind the ear, for the first time for a particular user, by placing the earpiece 100 behind the ear and moving the earpiece 100 in an upwards direction, so the second attachment element 122 cups the lobe of the ear. The first attachment element 120 may then be folded or bent in a downwards direction to fit over the top of the ear, for example over the helix of the ear. The earpiece 100 may be removed from the ear without readjusting or further deforming the first attachment element 120. For example, the second attachment element 122 may first be pulled away from the head and away from the lobe of the ear. Subsequently, the earpiece 100 may be lifted away from the ear, for example in an upwards or backwards direction with respect to a direction a user is facing. To refit the earpiece 100 or remount it behind the ear subsequently for the same user, the first attachment element 120 may be hooked or hung over the top of the ear, and the second attachment element 122 may be pushed under the lobe of the ear until the second attachment element 122 cradles the lobe, with the earpiece 100 positioned behind the ear of the user. The earpiece 100 may be worn on either ear.

[0049] With first and second attachment elements 120, 122 such as those described above, the earpiece 100 may be securely mounted behind the ear of the user. This can allow the earpiece 100 to be used in turbulent environments or in zero-gravity environments, such as space, without falling off or being pulled off. Thus, the earpiece 100 can be worn while the user is participating in various different activities, such as exercise, while asleep or during a space walk, without being dislodged. This allows biometric data of the user, such as the blood oxygen saturation level, pulse rate or respiratory rate, to be measured or monitored continuously, without interruptions.

[0050] Example circuitry for use with the earpiece 100 of FIGS. 1 to 3 is illustrated in FIG. 4a and FIG. 4b. FIG. 4a illustrates schematically the left side of an example circuit 130 for use with the earpiece 100 and FIG. 4b illustrates schematically the right side of the example circuit 130 of which the left side is shown in FIG. 4a. A full description of every component of the example circuit 130 of FIGS. 4a and 4b is omitted here, as the skilled person would readily understand the function of standard electronic components such as resistors and capacitors, which are illustrated using standard symbols. However, some of the components of the example circuit 130 of FIGS. 4a and 4b will be discussed, to explain the functioning of the earpiece 100 in more detail.

[0051] The example circuit 130 includes a wireless power receiver 132, which in this example is a bq51050b wireless power receiver, available from Texas Instruments, Inc., Box 660199, 12500 TI Boulevard, Dallas, Texas 75266-0199, United States of America (although other wireless power receivers are possible in other examples). The wireless power receiver 132 receives power wirelessly and can be used to supply power to the power source. The power source itself is not shown in FIG. 4a. However, the position of the power source connectors 134 for connection to the power source are illustrated.

[0052] The wireless power receiver 132 may receive power from a charging apparatus, which may be plugged into mains power for example. This may be a suitable arrangement for example where the earpiece 100 is used by a patient in hospital or at home. For example, the charging apparatus may be attached or coupled to a headboard of a hospital bed or placed on a bedside table close to the patient's bed. In other examples, the charging apparatus may include a relatively large power capacity, such as a few thousand miUiampere hours (mAh), allowing the monitoring system of the earpiece 100 and the charging apparatus to be used away from mains power for a relatively long time. Such an arrangement may be suitable for example where the monitoring system is used in space, for mountaineers or in mining environments, in which mains power may not be easily or readily accessible. In such cases, the charging apparatus may itself be recharged using mains power when the user is able to access mains power.

[0053] The charging apparatus itself may be wearable. For example, the charging apparatus may be incorporated into clothes that are wearable by the user. This may be suitable where the user expects to wear a particular outfit or uniform for an extended period of time such as an astronaut on the International Space Station. In other examples, the charging apparatus may be in the form of a brooch or badge that may be fastened or detached to clothing or accessories. For example, the charging apparatus may be incorporated into a mission patch for astronauts, that can be pinned to the chest of the astronaut or a patch including the charging apparatus may be pinned to a rucksack of a mountaineer. In further examples, the charging apparatus may be incorporated in or attachable to headgear such as a hat or a helmet, for example for a miner.

[0054] The charging apparatus may be located at a distance from the earpiece, for example at a distance of between 0.5 centimetres and 50 centimetres, allowing the earpiece to charge wirelessly. However, in examples, the earpiece may be operable at further distances from the charging apparatus for a limited time period, such as 30 minutes, one hour or longer.

[0055] The left side of the example circuit 130 (shown in FIG. 4a) also includes a radiation source 136 configured to emit radiation of at least one predetermined wavelength and a radiation detector 138 configured to detect radiation of the at least one predetermined wavelength, although in other examples the circuitry may include a plurality of radiation sources and/or a plurality of radiation detectors. Together, the radiation source 136 and the radiation detector 138 form part of circuitry for measuring a biometric characteristic of a user, such as a blood oxygen saturation level, a pulse rate or a respiratory rate.

[0056] The blood oxygen saturation level is for example the concentration of oxy- haemoglobin in the blood divided by the sum of the concentration of the oxy- and deoxy- haemoglobin in the blood. The circuitry may for example be arranged to measure the peripheral oxygenation (Sp0 ₂ ), although in other examples the circuitry may measure the tissue oxygenation (St0 ₂ ) or the venous oxygenation (Sv0 ₂ ). A pulse rate is for example the number of heartbeats of a user over a predetermined time period such as one minute. A respiratory rate in examples is the number of breaths per minute.

[0057] In this example, the radiation source 136 is an infrared radiation source and the radiation detector 138 is an infrared radiation detector, although in other examples, the radiation source and the radiation detector may be configured to emit or detect radiation of other wavelengths than infrared, such as ultraviolet or visible light. As the skilled person will appreciate, infrared radiation is for example within the range of 700 nanometres to 1000 nanometres. In the example of FIG. 4a, the radiation source 136 is a VSMY2943G infrared emitter, available from Vishay Intertechnology, Inc., 63 Lancaster Avenue, Malvern, Pennsylvania 19355-2143, United States of America, although other radiation sources may be used in other examples. A suitable radiation detector 138 is a radiation detector 138 from the TSOP312, TSOP323, TSOP325, TSOP341, TSOP343 or TSOP345 series, also available from Vishay Intertechnology. Other examples of radiation sources and radiation detectors are given further below with reference to FIG. 8.

[0058] The radiation detector 138 is configured to detect radiation emitted from the radiation source 136 incident on the user and reflected back from the user to the radiation detector 138. The radiation source 136 in examples emits radiation with a pulsed or time-varying intensity, and may for example emit pulsed radiation at a plurality of different frequencies. For example, the radiation source 136 may alternately emit radiation within two different frequency bands. The intensity of the radiation detected by the radiation detector 138 for example depends on the blood volume and the concentration of oxy-haemoglobin in the blood. The haemoglobin in the blood has a different absorptivity depending on whether it is bound to oxygen or not and on the wavelength of radiation. Accordingly, the oxygenation of the blood can be determined from the intensity of the radiation detected by the radiation detector 138. The pulse rate and the respiratory rate of the user can also be determined from the intensity of the radiation detected by the radiation detector 138, as discussed further below.

[0059] To allow the radiation to be passed through blood vessels of the user, from the earpiece 100, the casing 102 may include a transmissive portion 140 transmissive for the radiation of the at least one predetermined wavelength emitted by the radiation source 136 and detected by the radiation detector 138. The transmissive portion 140 in examples is arranged for at least one of: the radiation of the at least one predetermined wavelength emitted by the radiation source 136 to exit the casing 102 or the radiation of the at least one predetermined wavelength to enter the casing 102 for detection by the radiation detector 138. For example, the transmissive portion 140 may be positioned in a region of the casing 102 which, with the earpiece 100 mounted behind the ear of the user, is adjacent to a particular region of the user's anatomy that is suitable for reflectance pulse oximetry.

[0060] The transmissive portion 140 is illustrated in FIG. 1. In examples such as FIG. 1, the casing 102 has a surface configured to be mounted adjacent to a head of the user, the surface including the transmissive portion 140. In FIG. 1, this surface is the far surface of the casing 102. The transmissive portion 140 may be of any suitable material and may be transmissive for more wavelengths of light than the at least one wavelength. For example, the transmissive portion may be transmissive for at least a portion of visible light.

[0061] As described above with reference to FIG. 1, in this example earpiece 100, the radiation source 136 and the radiation detector 138 for measuring the biometric characteristic of the user, together shown schematically with the reference numeral 108 in FIG. 1, is in the lower half of the earpiece 100. In this example, the transmissive portion 140 is located to be adjacent to a portion of a head of the user substantially behind a lower half of the ear of the user, with the earpiece 100 mounted behind the ear of the user. The portion of the head substantially behind the lower half of the ear may include a region of the head overlapped by the ear, for example within plus or minus 10% of the area overlapped by the ear. This portion of the head may therefore include the region of the head behind the lobe of the ear.

[0062] Measuring the biometric characteristic of the user may include detecting radiation reflected from a portion of a head of the user substantially behind a lower half of the ear of the user, with the earpiece 100 mounted behind the ear of the user. In such cases, the circuitry itself may be located such that it is adjacent to this portion of the head, with the earpiece 100 mounted behind the ear of the user, for example with the transmissive portion 140, the radiation source 136 and/or the radiation detector 138 also located adjacent to this portion of the head. For example, the radiation source may be arranged to emit the radiation of the at least one predetermined wavelength such that at least a portion of the at least one predetermined wavelength of radiation is incident on a portion of a head of a user substantially behind a lower half of the ear of the user, with the earpiece mounted behind the ear of the user.

[0063] In other examples, though, the radiation source 136 and/or the radiation detector 138 may be located away from this portion of the head. In such examples, the radiation may be directed towards this portion of the head for example using a similar optical arrangement, involving one or more reflectors for directing the radiation appropriately from the radiation source 136 to this portion of the head and for directing radiation received from this portion of the head to the radiation detector 138.

[0064] The radiation detector 138 in examples converts the changes in intensity of the radiation into a varying voltage signal. In the example circuit 130 of FIGS. 4a and 4b, the voltage signal produced by the radiation detector 138 is transferred to an amplifier 140, which amplifies the voltage signal for further analysis. The amplifier in this example is an operational amplifier, in this case a MCP601T-I/OT operational amplifier, available from Mouser Electronics, Artisan Building, Suite C, First Floor, Hillbottom Road, High Wycombe, Buckinghamshire HP12 4HJ, United Kingdom, although other amplifiers are possible in other examples. The amplifier 140 may for example operate in a non-inverting amplification mode.

[0065] The amplified voltage signal is transferred from the amplifier 140 to a processor 142, which is shown in FIG. 4b, which shows the right side of the example circuit 130, the left side of which is shown in FIG. 4a. The processor in this example is a nRF52832 processor, available from Nordic Semiconductor ASA, P.O. Box 436, Sk0yen, 0213 Oslo, Norway, although other processors are possible in other examples. The processor may include a microprocessor, a general purpose processor, a digital signal processor (DSP), an application specific integrated circuit (ASIC), a field programmable gate array (FPGA) or other programmable logic device, a discrete gate or transistor logic, discrete hardware components, or any suitable combination thereof designed to perform the functions described herein. A processor may also be implemented as a combination of computing devices, e.g., a combination of a DSP and a microprocessor, a plurality of microprocessors, one or more microprocessors in conjunction with a DSP core, or any other such configuration. For example, the circuitry may include at least one processor, such as a plurality of processors.

[0066] The at least one processor may for example include or be coupled to at least one memory, cache or storage. The at least one memory may include at least one of volatile memory and non-volatile memory. For example, the at least one memory may include a Random Access Memory (RAM), for example Static RAM (SRAM) or Dynamic RAM (DRAM) or a Read Only Memory (ROM). The at least one memory may be removable or non-removable from the earpiece 100. In the example of FIGS. 4a and 4b, the nRF52832 is a system on-a-chip including a Cortex-M4F processor, 512 kB (kilobytes) flash memory and 64 kB of RAM.

[0067] The at least one processor may be configured to control the operation of the earpiece 100, for example to measure the biometric characteristic of the user. In such cases, the at least one processor may be considered to form part of the circuitry

[0068] The at least one processor may be further configured to further process or analyse the data captured by the components of the example circuitry 130, such as the intensity data output by the radiation detector 138, representing the intensity of radiation reflected from blood vessels of the user. For example, the at least one processor may be configured to measure a plurality of biometric characteristics of the user.

[0069] For example, the circuitry (which may include the radiation source 136, the radiation detector 138 and the at least one processor 140, which itself may include or be coupled to at least one memory) may be further configured to measure at least one of a pulse rate of the user, a respiratory rate of the user, a temperature of the user, a vigilance level of the user (which sometimes corresponds to or is indicative of a consciousness or alertness level of the user) or a head acceleration of the user. In these examples, the circuitry may be arranged to generate measurement data indicative of at least one of these characteristics. The measurement data may be used in a variety of different ways, depending on the environment the earpiece 100 is to be used in and the health or expected health of the user (for example, whether the user is susceptible to health conditions, either due to their environment or due to an ongoing medical condition of the user).

[0070] The pulse rate of the user may be determined from the intensity of the radiation detected by the radiation detector 138. As the extent of absorption of the radiation differs for oxygenated blood and deoxygenated blood, the intensity of the radiation detected by the radiation detector 138 will also vary periodically because the amount of oxygenated blood varies over time, increasing with each heartbeat. This allows the pulse rate of the user to be determined. For example, the varying voltage signal representing the varying intensity of the radiation detected by the radiation detector 138 amplified by the amplifier 140 may be processed by the processor 142 to obtain the pulse rate.

[0071] The respiratory rate of the user may also be determined or estimated from the output of the radiation detector 138, for example the intensity of the radiation detected by the radiation detector 138, as the skilled person will appreciate.

[0072] The earpiece may also include an accelerometer, which can be used to measure the head acceleration of the user, and/or a temperature sensor for measuring the temperature of the user.

[0073] The vigilance level may be determined based on processing of other biometric characteristics of the user, for example based on a combination of the blood oxygen saturation level, the pulse rate and/or the respiratory rate.

[0074] The measurement of at least one biometric characteristic, such as a pulse rate of the user, a respiratory rate of the user, a temperature of the user, a vigilance level of the user or a head acceleration of the user, may be controlled by software or hardware. For example, appropriate firmware may be run on the at least one processor to perform measurements of at least one of these biometric characteristics. In examples, the circuitry may be configurable (for example by altering the software run by the circuitry or the hardware of the circuitry) to enable a range of physiological measurements to be carried out using data obtained using the earpiece. For example, the at least one memory may have sufficient capacity to enable complex algorithms to be run on the earpiece, in real time or in a time that is negligible or not noticeable to the user of the earpiece. The at least one processor may also or alternatively have a sufficiently large processing capability to enable measurement data obtained using the circuitry to be processed using complex algorithms, without having to transfer the measurement data to an external device for processing. [0075] For example, the earpiece may include an audible alarm system configured to sound an audible alarm in dependence on the measurement data. The audible alarm may be arranged to emit warning sounds that are sufficiently loud to wake a user up even in a noisy environments, for example with an ambient noise environment of up to 90 A-weighted decibels (db(A)).

[0076] In these examples, the audible alarm system may be sounded where one or more of the measured characteristics of the user meets or exceeds a threshold condition, such as a threshold condition representing a safe or normal level of the characteristic. If the earpiece is used in space, for example, the circuitry may be configured to sound the audible alarm when the blood oxygen saturation level of the user is at a level indicative of a potential onset of hypoxaemia, such as a blood oxygen saturation level of lower than 90%. In examples in which the circuitry is configured to measure the pulse rate of the user, the audible alarm may be sounded for example where the pulse rate of the user is determined to be less than 40 beats per minute. Where the circuitry is configured to measure the respiratory rate of the user, the audible alarm may be sounded for example where the respiratory rate of the user is above 30 breaths per minute. In cases where the circuitry is configured to measure the temperature of the user, the audible alarm may be sounded where the temperature is measured to be over 39 degrees Celsius. In all cases in which the earpiece includes an audible alarm system, the thresholds at which the audible alarm is sounded may be configurable, for example by a user, or the thresholds may be predetermined or preset.

[0077] In other examples, the earpiece may merely log events that meet or exceed a threshold or may alert the user in a different manner, for example via a notification on a client device, a text message or an email. The threshold at which an event is logged may differ from a threshold at which the audible alarm is sounded. For example, an event may be logged where a characteristic is determined to differ from a normal or acceptable operating band, but where the deviation is not sufficient for the health of the user to be at considerable risk. For example, the circuitry may be configured to log one or more of: a heart rate accelerating event, a heart rate decelerating event, a heart rate of over 110 beats per minute, a heart rate of under 50 beats per minute, active periods such as periods of moving, standing and doing exercise, periods in bed, sleeping periods, so-called "nodding dog" events where the user is falling asleep (and an audible alarm may be sounded for such events), transitions in consciousness, a respiratory rate of over 20 breaths per minute (tachypnoea), a temperature of the user of over 38 degrees Celsius, a temperature of the user of less than 35 degrees Celsius.

[0078] In further examples, the circuitry of the earpiece may be configured to predict future medical events based on the measurement data. For example, the circuitry may be configured to generate a predicted likelihood of onset of a medical condition, such as a stroke or a heart attack, based on the measurement data. Likelihood predictions such as this may be made based on processing of the measurement data using the at least one processor of the earpiece, which may implement any suitable algorithm for predicting medical events or the onset, start or escalation of medical conditions based on biometric characteristics such as blood oxygen saturation level, pulse rate, respiratory rate, vigilance level, head acceleration and/or temperature.

[0079] In these cases, the circuitry may be configured to sound an audible alarm in dependence on the predicted likelihood. For example, if the predicted likelihood satisfies a likelihood condition, such as a condition that indicates that the onset of the medical condition is imminent or very likely, the audible alarm may be sounded to alert the user to take immediate action to avoid the onset of the medical condition. In other examples, the user be alerted in an alternative manner such as via an application notification, via text message or via e-mail.

[0080] The measurement data generate by the circuitry may be transmitted wirelessly for receipt by a client device such as a mobile device or smartphone, a laptop, a server device, a tablet device or another electronic or computing device such as a central medical server of a hospital or medical centre. In the example of FIGS. 4a and 4b, the processor 142 supports Bluetooth Low Energy and therefore can be used to transfer the measurement data from the on-chip memory of the processor 142 via Bluetooth Low Energy to the client device. For example, measurement can be transferred over a distance of up to around 6 metres using Bluetooth 4 wireless technology. The earpiece can typically operate for an extended period of time, such as up to around 48 hours, without being synced, for example without the measurement data being transferred to a client device, without losing data. In examples, the Bluetooth Low Energy (LE) Pulse Oximeter Profile standard may be used as a primary interface to third-party applications (apps). The measurement data may be transmitted to the client device periodically or at regular intervals, in response to a request for transmission of the data (for example from the client device), in dependence on a measured characteristic meeting or exceeding a threshold level, or in dependence on a positive prediction that a medical event is likely to occur. For example, if the circuitry determine that a likelihood of a medical event such as a stroke or heart attack meets or exceeds a threshold likelihood, the measurement data or an alert may be transferred to the client device, alone or in conjunction with the sounding of an audible alarm.

[0081] The client device may include appropriate software for collating or receiving data from the earpiece. For example, the measurement data may be displayed on the client device for the user to see or the software may forward the measurement data to secure data services on a remote server or on the cloud. The measurement data may be displayed using dashboards displaying real time measurements of the characteristics of the user or particular, predetermined or user-selected measurements of the characteristics. The client device may receive measurement data from a plurality of different earpieces, for example mounted on a plurality of different users. In such cases, a dashboard may display information relating to a plurality of different users, such as a ward of patients or a spacecraft of astronauts.

[0082] An example of a printed circuit board (PCB) 144 showing the position of the components of the example circuit 130 of FIGS. 4a and 4b relative to each other is shown in FIG. 5. The PCB 144 in examples such as FIG. 5 has a trapezoidal shape to minimise the size of the casing 102 to house the PCB 144. This shape also ensures the PCB is firmly secured inside the earpiece casing, ensuring the system's longevity. In other examples, though, the PCB 144 may have other shapes. The PCB 144 includes three mounting holes 146a, 146b, 146c present on the board, although in other examples the PCT 144 may be mounted differently or may include more or fewer mounting holes.

[0083] The example circuit 130 schematics and printed circuit board (PCB) 144 layout illustrated in FIGS. 4a, 4b and 5 do not show the locations of the antennas needed for operation of the bq51050b wireless power receiver and charger. However, any suitable location may be used, as the skilled person will appreciate. In examples, the Rx antenna (receiver antenna) trace is positioned between AC1 and AC2 shown in FIG. 4a.

[0084] The PCB 144 layout shown in FIG. 5 differs from the layout of the components in the example of FIGS. 1 to 3. In FIG. 5, the connectors 134 for the power source (and hence the power source itself), the radiation source 136 and the radiation detector 138 are all at one end of the PCB 144. In this example, the power source, the radiation source 136 and the radiation detector 138 are all located in the upper half of the earpiece 100, with the earpiece 100 orientated for mounting behind the ear of the user. However, in the example of FIGS. 1 to 3, the power source 106 (and the connectors for the power source, not illustrated in FIGS. 1 to 3), is in the upper half of the earpiece 100, whereas the radiation source and detector 108 are in the lower half of the earpiece 100 with the earpiece orientation for mounting behind the ear of the user. As will appreciated, there are a variety of different possible shapes or positionings for the earpiece and components of the earpiece.

[0085] FIGS. 6a to 6d show some examples of different earpieces 200, 300, 400, 500. Features of FIGS. 6a to 6d similar to corresponding features of FIG. 1 are labelled with the same reference numerals but incremented by 100, 200, 300 and 400 respectively; corresponding descriptions are to be taken to apply. In FIGS. 6a to 6d, solid elements are shown with dotted shading.

[0086] The earpiece 200 of FIG. 6a is similar to that of FIG. 1 but has a wider middle section and a more tapered or narrower upper end section and the first attachment element 202 is formed of a wire with a solid element at the free end of the wire, which in this example is in the shape of sphere. The second attachment element 222 is similar to that of the first attachment element 122 and has a substantially v-shape but is formed of a loop of wire rather than a single, non-looped, length of wire.

[0087] The earpiece 300 of FIG. 6b is similar to that of FIG. 6a but is narrower and the solid element at the end of the first attachment element 320 is an elongate or tear drop shape rather than a sphere or ball shape.

[0088] The earpiece 400 of FIG. 6c is similar to that of FIG. 6b but does not include a first attachment element, instead including solely a second attachment element 422. The earpiece 400 of FIG. 6c may for example include an adhesive surface for attaching behind the ear of the user.

[0089] The earpiece 500 of FIG. 6d is similar to that of FIG. 1 but has a solid first attachment element 520 which is thicker than the first attachment element 120 of FIG. 1. However, the first attachment element 520 of FIG. 6d may also be flexible or reversibly deformable.

[0090] The above embodiments are to be understood as illustrative examples. Further embodiments are envisaged. The examples of FIGS. 1 to 6 are examples relating to an earpiece, for example for biometric monitoring of a user. However, as described above in section 1, which describes a particular example, in other examples an earpiece may be used in conjunction with a gas sensing device. The gas sensing device may be any suitable gas sensor, such as the K-30 sensor described above for detecting carbon dioxide. In such cases, data relating to the concentration, proportion or level of a particular or predetermined gas in a gas sample incident on the gas sensing device may also be transferred to the circuitry of the earpiece, for example to the memory of the earpiece for processing by the processor of the earpiece. This data may be transferred via a wired connection or wirelessly, for example via Bluetooth Low Energy. In such examples, the data relating to the proportion of the predetermined gas in the gas sample may be analysed or processed together with the measurement data relating to one or more characteristics of the user, for example to assess whether the environment the user is exposed to is safe, or whether an audible alarm should be sounded to warn the user to move to a different environment. For example, a threshold condition above which an audible alarm is sounded may depend on both the proportion of the predetermined gas as well as the level of the particular characteristics of the user measured by the circuitry of the earpiece.

[0091] In other examples, the monitoring system may include an environmental sensor arranged to measure at least one environmental characteristic. The at least one environmental characteristic comprises at least one of: a proportion of particulate matter in a gas sample; a pollen level; a radiation level; an ambient light level; or a noise level. Particulate matter may for example me microscopic solid or liquid matter suspended in the gas sample such as air or an ambient gas. The radiation level may be for example the level, proportion or quantity of harmful radiation such as gamma radiation or particle radiation such as alpha radiation, beta radiation or neutron radiation, which may be measured using a Geiger counter, for example. The ambient light level for example may be detected by a photosensor or photodetector and may be indicative of the intensity of light incident on the photosensor or photodetector. The environmental sensor may be any suitable sensor for measuring an environmental characteristic such as these, and may be capable of measuring a plurality of different environmental characteristics. In examples, the environmental system may include a gas sensing device such as that described above.

[0092] The gas sensing device and/or the environmental sensor may include the charging apparatus described above with reference to FIG. 4a, for example. For example, the gas sensing device and/or the environmental sensor and the charging apparatus may be incorporated in an item of clothing or wearable patch. This can simplify the use of the monitoring system, reducing the number of separate components to be kept track of or carried by the user.

[0093] FIG. 7 shows schematically an example of a monitoring system 148. In the example of FIG. 7, an earpiece 100 (which in this example is the earpiece 100 of FIG. 1) receives power wirelessly via at least one network 150. In this example, the earpiece 100 receives the power wirelessly from a charging apparatus 152, such as that described above, via a wireless charging protocol. The charging apparatus 152 in this example includes an environmental sensor 154; the charging apparatus 152 and the environmental sensor 154 in this case are integrated into a mission patch for an astronaut. Thus, references to an environmental sensor or a gas sensing device including a charging apparatus may be considered to also refer to the charging apparatus including the environmental sensor or gas sensing device, or to the charging apparatus and the environmental sensor or gas sensing device being co-located or present within a common component, item of clothing or accessory.

[0094] Measurement data generated by the earpiece 100 is transferred to a client device 156, such as a mobile phone or smartphone, a personal digital assistant, a tablet or laptop computer or a personal computer, via Bluetooth Low Energy in this example, as the at least one network 150 in this example includes a Bluetooth network. However, in other examples, the measurement data or data based on the measurement data may be transferred from the earpiece 100 to the client device 156 via a different network. For example, the at least one network 150 may include a Public Switched Telephone Network (PSTN) or a cable provider's network system. Alternatively, the at least one network 150 may include wireless telecommunications systems such as those using the Universal Mobile Telecommunications System (UMTS) or any of the Long Term Evolution (LTE) standards, which may provide a communications medium for fixed or mobile client devices. These latter network systems may in turn be connected to a series of one or more networks comprising servers, routers and other networking equipment that communicate using protocols such as Transmission Control Protocol (TCP) and Internet Protocol (IP). If the client device 156 includes a mobile device such as a smartphone it may have an integrated telecommunications module for wirelessly communicating with a core network coupled to one or more TCP/IP networks; likewise, if the client device 156 includes a laptop or tablet computer it may have an externally-coupled telecommunications modem (a so- called "dongle", typically coupled via USB) for wireless communication with the core network and the wider Internet.

[0095] In the example of FIG. 7, a server device 158 is arranged to receive the measurement data or data based on the measurement data from the client device 156 via the at least one network 150. The server device 158 may store this data securely, for example for future access or analysis by the client device or by another computing device. In examples, the server device 158 forms part of a cloud computing storage system.

[0096] FIG. 8 shows schematically an example sensing circuit 160 for measuring a biometric characteristic of a user using reflectance pulse oximetry, which may be used with the earpiece 100 of FIG. 1 for example. As in the description of the example circuit 130 of FIGS. 4a and 4b, a full description of every component of the example sensing circuit 160 of FIG. 8 is omitted here, as the standard symbols are used for standard electronic components.

[0097] The sensing circuit 160 of FIG. 8 is for measuring a biometric characteristic of a user and will typically receive power from a power source such as a battery (not illustrated in FIG. 8). The power may be received wirelessly, as described above with reference to FIGS. 4a and 4b.

[0098] The sensing circuit 160 in the example of FIG. 8 includes two pulse oximetry integrated circuits 162a, 162b, each for controlling the operation of two sets of light emitting diodes (LEDs) 164a, 164b respectively, each set including three individual LEDs, and the operation of a photosensor 166a, 166b respectively. In this example, the pulse oximetry integrated circuits 162a, 162b are each AFE4404 integrated circuits, available from Texas Instruments, although other circuitry may be used to control at least one radiation source and at least one radiation detector for reflectance pulse oximetry in other examples. The pulse oximetry integrated circuits 162a, 162b in this example also amplify and sample the outputs of the two photosensors 166a, 166b, although in other examples the amplification and/or sampling may be performed using separate components or amplification and/or sampling may be omitted.

[0099] In this example, there are six LEDs, each arranged to emit radiation of a different wavelength or frequency. However, in other examples there may be more or fewer than 6 radiation sources. For example, there may be four light sources: one arranged to emit infrared light, one arranged to emit red light, one arranged to emit green light and one arranged to emit blue light.

[00100] An example arrangement of the six LEDs 164a, 164b and the photosensors 166a, 166b of the sensing circuit 160 of FIG. 8 is illustrated in FIG. 9. In FIG. 9, a first set of three LEDs 164a controlled or driven by a first pulse oximetry integrated circuit 162a (labelled with the reference numerals 164a', 164a", 164a' ") are arranged to surround an infrared detector 166a and a second set of three LED si 64b controlled or driven by a second pulse oximetry integrated circuit 162b (labelled with the reference numerals 164b', 164b", 164b' ") are arranged to surround a photodetector 166b, sometimes referred to as a visible radiation sensor. In examples at least one of the first set of LEDs is arranged to emit infrared radiation and at least one of the second set of LEDs is arranged to emit visible radiation. The first and second sets of LEDs 164a, 164b are orientated to emit light in a direction of a region of the head behind the ear for reflectance pulse oximetry, with the earpiece 100 mounted behind the ear of the user. For example, the first and second sets of LEDS 164a, 164b may be located to emit light towards a region of the head behind or substantially behind a lower half of the ear of the user, with the earpiece 100 mounted behind the ear of the user.

[00101] As will be appreciated, the arrangement of the LEDs illustrated in FIG. 9 is merely an example. In other examples, the arrangement of the LEDs and/or the infrared detector and/or the photodetector may differ. For example, there may be solely one radiation detector for detecting radiation over a plurality of different wavelengths.

[00102] Referring back to FIG. 8, the example sensing circuit 160 also includes additional sensors for performing additional measurements than those using data obtained from the output of the photosensor 166a, 166b. In this example, the sensing circuit 160 includes a temperature sensor 168, which in this example is a MCP9800-A0T-M/OT, available from Microchip Technology Inc., 2355 West Chandler Boulevard, Chandler, Arizona 85224-6199, United States of America, and an accelerometer 170, which in this example is a combined three-axis accelerometer and three-axis gyroscope integrated circuit, such as the LSM330DLC, available from STMicroelectronics S.A., Chemin du Champ des Filles, Plan-les-Ouates, Switzerland. In other examples, though, the sensing circuit may include other sensors.

[00103] The sensing circuit 160 is controlled similarly to the example circuit 130 of FIGS. 4a and 4b by at least one processor 172, which in this example is a nRF52832 chip. The at least one processor 172 in this example is connected to an audible alarm 174, in this example an onboard buzzer, for alerting the user for example in dependence on the measurement data or on the predicted likelihood discussed above.

[00104] An example of the positioning of various components of the example sensing circuit 160 of FIG. 8 is illustrated schematically in FIG. 10. FIG. 10 shows an earpiece 600, which may have a casing 602 similar to the casing 102 of the earpiece 100. The earpiece 600 of FIG. 10 may also include a first attachment element and/or a second attachment element similar to or the same as the first attachment element and/or the second attachment element of the earpieces 100, 200, 300, 400, 500 of any of FIG. 1 or FIGS. 6a, 6b, 6c or 6d. The example earpiece 600 of FIG. 10 is illustrated in an orientation suitable for mounting behind an ear of a user. In other words, the upper end of the earpiece 600 would correspond with the upper ear and the lower end of the earpiece 600 would correspond with the lobe of the ear, with the earpiece 600 mounted behind the ear.

[00105] In FIG. 10, in addition to the sensing circuit 160 of FIG. 8, further components are shown, including connectors 176 for connecting a power source, which may be similar to the power source described above with reference to FIG. 1. Accordingly, in this example, the power source would be located in an upper portion or upper half of the earpiece 600, such that the earpiece 600 remains stably positioned behind the ear of the user.

[00106] In FIG. 10, the pulse oximetry components 178, which in this example include the first and second sets of LEDs 164a, 164b and the two radiation detectors or photosensors 166a, 166b illustrated in FIGS. 8 and 9, are located towards an opposite end of the earpiece 600 than the connectors 176 for the power source. Thus, in this example, the pulse oximetry components 178 are arranged for performing pulse oximetry based on reflectance of the emitted radiation from a portion of the head behind a lower part of the ear, such as a portion of the head behind the lobe of the ear. In examples, measurements taken in this region of the head may be more accurate than readings taken elsewhere.

[00107] Further examples relate to an earpiece mountable behind an ear of a user, the earpiece including a casing and, disposed within the casing, a power source and circuitry arranged to measure a biometric characteristic of a user, the power source arranged to supply power to the circuitry. The earpiece in these further examples may be similar to or the same as the earpiece described in examples above, for example the earpieces 100, 200, 300, 400, 500 illustrated in FIGS. 1, 6a, 6b, 6c and 6d but with the circuitry for measuring a biometric characteristic of the user using reflectance pulse oximetry replaced with circuitry arranged to measure a biometric characteristic of the user using other measuring devices or apparatus. The biometric characteristic may be at least one of: a blood oxygen saturation level of the user, a pulse rate of the user, a respiratory rate of the user, a temperature of the user, a consciousness level of the user, or a head acceleration of the user, for example. For example, the circuitry may be similar to that for performing reflectance pulse oximetry, and may include a radiation source and a radiation detector similarly to the example circuit 130 of FIGS. 4a and 4b, but arranged to output a different biometric characteristic than those described above. Alternatively, and as the skilled person will appreciate, the circuitry may differ from that of the example circuit 130 of FIGS. 4a and 4b, for example for obtaining a biometric characteristic using other methods than reflectance pulse oximetry. For example, the circuitry may include other measurement devices such as at least one of a temperature sensor, an accelerometer, a global positioning system (GPS) or a microphone.

[00108] Yet further examples are envisaged in accordance with the following numbered clauses:

1. A monitoring system comprising:

a biometric monitoring device comprising:

a power source; and

circuitry arranged to measure a biometric characteristic of a user, the power source arranged to supply power to the circuitry; and a charging apparatus for charging the power source of the biometric monitoring device.

2. The monitoring system according to clause 1, wherein the charging apparatus is arranged to wirelessly charge the power source of the biometric monitoring device.

3. The monitoring system according to clause 1 or clause 2, wherein the charging apparatus is comprised by a gas sensing device arranged to measure a proportion of a predetermined gas in an incident gas incident on the gas sensing device.

4. The monitoring system according to clause 3, wherein the predetermined gas is carbon dioxide.

5. The monitoring system according to any one of clauses 1 to 4, wherein the biometric characteristic is at least one of: a heart rate or a blood oxygen saturation level of the user.

[00109] It is to be understood that any feature described in relation to any one embodiment may be used alone, or in combination with other features described, and may also be used in combination with one or more features of any other of the embodiments, or any combination of any other of the embodiments. Furthermore, equivalents and modifications not described above may also be employed without departing from the scope of the accompanying claims. APPENDIX

[0001] For an example bq5105b wireless power receiver and battery charger clip, the maximum current during charging (Icharging) is 1.5 amps (A) and the output potential is 4.20 volts (V), 4.35 V, 4.40 V. The input power may be received from a "receiver coil" placed between pins AC1 and AC2 as shown in FIG. 4a.

[0002] From the datasheet for the nRF52832 chip (which is for example the processor controlling the operation of the earpiece), the worst case typical power consumption is 477.96 mV (millivolts).

[0003] With a maximum discharge current of 480 mA (milliamps) and software on the nRF52832 chip (which is the largest power consumer) that limits the power-intensive operations when the unit is operating only on battery power. For example, if the Varta V250H battery is used, this battery would be suitable for providing on-board buffer power. The life expectancy of up to 6 years makes the battery suitable for high amounts of charging and discharging expected from operation in the earpiece device.

[0004] Assuming a fast charging current of 120 mA is applied and wireless power transfer to the device has a 25% efficiency (although the actual efficiency is likely to be higher), the charging current from the bq5105b wireless power receiver maybe calculated as:

Icharging = 0.25 X 1.5 = 0.375

[0005] Using on-board power control circuity, the output potential and current from the bq5105b can be converted to a required battery input of 1.2 V at 120 mA. This enables the onboard battery to charge (in a worst case scenario when the battery is completely discharged) in 3 hours, making earpiece only operation (i.e. with no external power) viable.

[0006] The nominal capacity of the battery is 240 mAh (milliampere hours). As the typical peak power consumption of the device can be managed to be around 480 mA, a nominal device lifetime of 30 minutes can be achieved with this setup (i.e. a battery that fits in the earpiece).

[0007] Relevant details of the nRF52832 chip used in the calculation above are taken from the product specification of the nRF52832 chip.