Biosensing wearable device with integrated transducers for contact pressure quantification

Abstract

A wearable biosensing system includes a ring frame, a contact chassis, and a biosensing unit. The ring frame defines a passageway to receive a finger of a user therein. The contact chassis applies contact pressure to the skin surface of the user. The biosensing unit is coupled to the contact chassis to measure pressure data suitable for determining physiological signals of the user.

Description

BIOSENSING WEARABLE DEVICE WITH INTEGRATED TRANSDUCERS FOR CONTACT PRESSURE QUANTIFICATIONCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This nonprovisional application claims the benefit and priority, under 35 U.S.C. § 119(e) and any other applicable laws or statutes, to U.S. Provisional Application No. 63 / 571 ,087 filed on March 28, 2024 and U.S. Provisional Application No. 63 / 721 ,01 1 filed on November 15, 2024, the entire disclosures of both of which are hereby expressly incorporated herein by reference.STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT

[0002] This invention was made with government support under Grant No. EEC- 1648451 awarded by the National Science Foundation. The government has certain rights in the invention.FIELD OF THE DISCLOSURE

[0003] The present disclosure relates generally to wearable biosensing systems, and more specifically, to wearable biosensing systems with strain gauges.BACKGROUND

[0004] Wearable devices that capture and monitor various health parameters are highly desirable. For instance, a wearable device that is capable of monitoring risk factors of a disease state of a patient can allow people the comfort and ease of performing daily activities with the confidence that their medical state is being observed. However, such devices are sometimes uncomfortable, invasive, and can suffer from inaccurate, interrupted analysis of parameters. Therefore, there exists a need to develop new devices and methods to provide improved and comprehensive quantification of disease risk factors with greater accuracy.SUMMARY

[0005] The present disclosure may comprise one or more of the following features and combinations thereof.

[0006] According to an aspect of the present disclosure, a wearable biosensing system includes a ring frame sized to receive the finger of a user, a contact chassis, and a biosensing unit. The ring frame extends around an axis to define a passageway that can receive the finger of the user therein. The contact chassis applies a contact pressure to a skin surface of the user. The biosensing unit is coupled to the contact chassis and configured to measure pressure data suitable for determining physiological signals of the user.

[0007] In some embodiments, the ring frame includes an inner wall adapted to contact the skin surface of the user and an outer wall opposite the inner wall. The ring frame defines an interior space between the inner wall and the outer wall.

[0008] In some embodiments, the contact chassis includes a pressure applicator that extends from the interior space into the passageway of the ring frame and a bridge fixed to the ring frame. The biosensing unit is coupled to the bridge and located within the interior space of the ring frame. The biosensing unit illustratively includes a plurality of strain gauges.

[0009] According to another aspect of the present disclosure, a wearable biosensing system includes a case configured to contact a user, a contact chassis, and a biosensing unit. In some embodiments, the case is coupled to the user via a strap. In some embodiments, the case is adhered to the user via an adhesive material. The contact chassis applies a contact pressure to a skin surface of the user. The biosensing unit is coupled to the contact chassis and configured to measure pressure data suitable for determining physiological signals of the user.

[0010] These and other features of the present disclosure will become more apparent from the following description of the illustrative embodiments.BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Fig. 1 is a perspective view of a wearable biosensing system coupled to a finger of a user, the system including a ring frame that extends around the finger, a contact chassis located at least partially in the ring frame, and a biosensing unitlocated in the ring frame and configured to measure pressure data suitable for determining physiological signals of the user;

[0012] Fig. 2 is an enlarged view of the wearable biosensing system of Fig. 1 showing that the contact chassis includes a pressure applicator that extends through the ring frame toward the finger to apply a contact pressure to a skin surface of the finger;

[0013] Fig. 3 is a front sectional view of the system of Fig. 2 showing that the contact chassis includes a bridge coupled to the pressure applicator and extending about the ring frame, and further showing that the biosensing unit includes a plurality of strain gauges coupled to the bridge;

[0014] Fig. 4 is a back sectional view of the system of Fig. 2 showing that the system further includes a power unit having a rechargeable battery and an inductor charge coil configured to wirelessly recharge the rechargeable battery;

[0015] Fig. 5 is a perspective view of another wearable biosensing system coupled to a finger of a user, the system including a ring frame that extends around the finger, a contact chassis located at least partially in the ring frame, and a biosensing unit located in the ring frame and configured to measure pressure data suitable for determining physiological signals of the user;

[0016] Fig. 6 is a front view of the system of Fig. 5;

[0017] Fig. 7 is a back view of the system of Fig. 5 showing that the ring frame is formed to include a wire-relief channel to allow wires to pass therethrough;

[0018] Fig. 8 is a sectional view of the system of Fig. 5 showing that the contact chassis includes a pressure applicator extending partially around the ring frame and a bridge coupled to the pressure applicator;

[0019] Fig. 9 is a sectional view similar to Fig. 8 showing that the contact chassis is moveable relative to the ring frame via a driver to allow the ring frame to fit around fingers of various sizes;

[0020] Fig. 10 is a front view of the system of Fig. 9 showing that the contact chassis further includes a shim that is coupled between the ring frame and the pressure applicator after the ring frame has been sized to fit around the finger of the user;

[0021] Fig. 11 is a perspective view of the contact chassis and the biosensing unit of Fig. 5 showing that the biosensing unit includes a plurality of strain gauges coupled to the bridge;

[0022] Fig. 12 is another perspective view of the contact chassis and the biosensing unit similar to Fig. 11 ;

[0023] Fig. 13 is a perspective view of another wearable biosensing system configured to be coupled to a finger of a user, the system including a ring frame that extends around the finger, a contact chassis located at least partially in the ring frame, and a biosensing unit located in the ring frame and configured to measure pressure data suitable for determining physiological signals of the user;

[0024] Fig. 14 is an exploded view of the system of Fig. 13 showing that the system includes, from top to bottom, a top portion of the ring frame, a communication module, a rechargeable battery, a plurality of screws, the contact chassis with the biosensing unit coupled thereto, an inductor charge coil, and a bottom portion of the ring frame;

[0025] Fig. 15 is an enlarged view of a first bridge of the contact chassis of Fig. 14 showing that a plurality of strain gauges is coupled to the first bridge;

[0026] Fig. 16 is an enlarged view of another embodiment of a first bridge of a contact chassis for use with the wearable biosensing system of Fig. 13;

[0027] Fig. 17 is an exploded view of another wearable biosensing system similar to the wearable biosensing system of Fig. 14;

[0028] Fig. 18 is a perspective view of another wearable biosensing system strapped to an arm of a user;

[0029] Fig. 19 is an enlarged view of the system of Fig. 18 showing that the system includes a case, a contact chassis located inside of the case, and a biosensing unit coupled to the contact chassis and configured to measure pressure data suitable for determining physiological signals of the user;

[0030] Fig. 20 is an exploded view of the system of Fig. 19 showing that the system includes, from top to bottom, a driver, a case, a plurality of screws, two strain gauges, a bridge, two strain gauges, a mount, and a pressure applicator;

[0031] Fig. 21 is a perspective view of another wearable biosensing system strapped to an arm of a user;

[0032] Fig. 22 is an enlarged view of the system of Fig. 21 showing that the system includes a case and a plurality of pressure applicators extending outwardly from the case to apply a contact pressure to the skin surface of the user;

[0033] Fig. 23 is an exploded view of the system of Fig. 22 showing that the system includes, from top to bottom, a top portion of the case, a rechargeable battery, a communication module, a mount, a plurality of bridges, a biosensor, the plurality of pressure applicators, and a bottom portion of the case;

[0034] Fig. 24 is a perspective view of another wearable biosensing system fixed to a skin surface of a user, the system including a biosensing unit configured to measure pressure data suitable for determining physiological signals of the user;

[0035] Fig. 25 is an enlarged view of the system of Fig. 24 showing that the wearable biosensing system includes a case having an adhesive material coupled thereto to adhere to the skin surface of the user;

[0036] Fig. 26 is an exploded view of the system of Fig. 25 showing that the system includes, from top to bottom, a driver, a case, an inductor charge coil, a communication module, a plurality of screws, two strain gauges, a bridge, two strain gauges, a mount, and a pressure applicator;

[0037] Fig. 27 is a perspective view of another wearable biosensing system configured to be fixed to a skin surface of a user, the system including a biosensing unit configured to measure pressure data suitable for determining physiological signals of the user;

[0038] Fig. 28 is an exploded view of the system of Fig. 27 showing that the system includes, from top to bottom, a top portion of a case, a communication module, a biosensor, two strain gauges, a bridge, two strain gauges, a plurality of pressure applicators, a bottom portion of the case, and a plurality of electrodes;

[0039] Fig. 29 is an enlarged view of one of the pressure applicators of Fig. 28;

[0040] Fig. 30 is a perspective view of one of the systems of Figs. 1 -29 extending around a toe of the user or coupled to a leg of the user;

[0041] Fig. 31 is a perspective view of one of the systems of Figs. 18-29 coupled to an arm of the user;

[0042] Fig. 32 is a graph showing a waveform generation by one of the systems of Figs. 1 -31 ;

[0043] Fig. 33 is a graph showing calculated blood pressure of the user based on measurements by one of the systems of Figs. 1 -31 ; and

[0044] Fig. 34 is a graph showing signals from the biosensor unit of one of the systems of Figs. 1 -31 .DETAILED DESCRIPTION OF THE DRAWINGS

[0045] For the purposes of promoting an understanding of the principles of the disclosure, reference will now be made to a number of illustrative embodiments illustrated in the drawings and specific language will be used to describe the same.

[0046] The present disclosure provides a wearable biosensing system 10, 210, 310, 31 O', 410, 510, 610, 710 that is capable of actively monitoring several biomarkers for robust signal acquisition. In some embodiments, the system 10, 210, 310, 310' is ring shaped and configured to extend around a finger or a toe of a user. In some embodiments, the system 410, 510 is configured to be coupled to a wrist, an arm, or a leg of a user via a strap. In some embodiments, the system 610, 710 is configured to adhere to the user via an adhesive material.

[0047] The systems 10, 210, 310, 310', 410, 510, 610, 710 are configured to continuously determine, detect, or measure physiological signals of the user. Analysis of the physiological signals allows for advanced dynamic detection of biomarkers such as, but not limited to, heart rate, heart rate variability (HRV), heart rate morphology, cardiac pulse wave morphology, respiration rate, blood pressure (BP), cardiovascular performance, cardiac output, stroke volume, vascular tone, vascular assessment, hypo or hyperglycemic events, blood oxygenation (SpO2), tissue oxygenation, body systemic pressure, among others. The physiological signals allow biomarkers to be monitored to reveal diseases or conditions, such as, but not limited to, cardiac diseases, heart diseases, cardiac arrhythmias, the onset of hypo / hyperglycemic events, peripheral artery disease, coronary artery diseases, atherosclerosis, blood clots, early onset of a seizure, hypertension, white coat hypertension, masked hypertension, other hypertensive and hypotensive states.

[0048] The wearable biosensing system 10 includes a ring frame 12, a contact chassis 14, and a biosensing unit 16, as shown in Figs. 1-3. The ring frame 12 extends around an axis 11 to define a passageway 18 extending through the ring frame 12. The finger (or toe) of the user is received in the passageway 18. The contact chassis14 is coupled to the ring frame 12 and configured to apply a contact pressure to skin surface of the user, for example, the skin surface of the finger. The biosensing unit 16 is coupled to the contact chassis 14 and configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the contact chassis 14 and the skin surface.

[0049] The ring frame 12 includes an inner wall 121 adapted to contact the skin surface of the user and an outer wall 120 opposite the inner wall 12I, as shown in Fig. 2. The outer wall 120 is located radially outward of the inner wall 121 relative to the axis 1 1 . The ring frame 12 defines an interior space 20 radially between the inner wall 12I and the outer wall 120. The biosensing unit 16 and at least a portion of the contact chassis 14 are located in the interior space 20. The inner wall 121 may be formed to include an opening 22 that a portion of the contact chassis 14 extends through, as shown in Fig. 2. The size of the ring frame 12 (i.e . , a diameter of the ring frame 12) may be adjusted to accommodate different finger or toe sizes.

[0050] The contact chassis 14 includes a pressure applicator 24, a bridge 26, and a mount 28, as shown in Fig. 3. The pressure applicator 24 is coupled to the bridge 26 and extends from the interior space 20, through the opening 22 of the inner wall 12I, and into the passageway 18 of the ring frame 12. In this way, the pressure applicator 24 extends toward the axis 11 and toward the skin surface of the user to apply the contact pressure to the skin surface of the user. The bridge 26 extends circumferentially partway about the axis 11 in the interior space 20 of the ring frame 12. The mount 28 is coupled with the bridge 26 and the ring frame 12 to fix the contact chassis 14 to the ring frame 12.

[0051] The bridge 26 extends between a first end 26A and a second end 26B, as shown in Fig. 3. In some embodiments, the bridge 26 extends only partially circumferentially about the axis 11 . The pressure applicator 24 is located circumferentially between the first end 26A and the second end 26B of the bridge 26. The bridge 26 defines a first straight portion 30, a second straight portion 32 circumferentially spaced apart from the first straight portion 30, and a curved portion 35 extending between and interconnecting the first straight portion 30 and the second straight portion 32. The pressure applicator 24 is coupled to the curved portion 35. At least part of the biosensing unit 16 is coupled to the first and second straight portions 30, 32.

[0052] The mount 28 illustratively includes a first mount 28A coupled to the first end 26A of the bridge 26 and a second mount 28B coupled to the second end 26B of the bridge 26, as shown in Fig. 3. The first mount 28A and the second mount 28B are fixed to the ring frame 12. In some embodiments, the first mount 28A is coupled to a first mount post of the ring frame 12, and the second mount 28B is coupled to a second mount post of the ring frame 12. The mount 28 is located in the interior space 20 of the ring frame 12.

[0053] The biosensing unit 16 is mounted to the bridge 26 of the contact chassis 14, as shown in Fig. 3. The biosensing unit 16 is located in the interior space 20 of the ring frame 12. The biosensing unit 16 illustratively includes a first strain gauge 34 and a second strain gauge 36 circumferentially spaced apart from the first strain gauge 34 about the axis 11 . The first and second strain gauges 34, 36 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 24 and the skin surface. For example, the strain gauges 34, 36 may quantify the strain on the bridge 26. The strain may be linearly correlated with contact pressure and pressure response, which allows the system 10 to measure blood pressure and cardiac differential fluid flow morphology of the user directly.

[0054] The first strain gauge 34 is mounted to the first straight portion 30 of the bridge 26, and the second strain gauge 36 is mounted to the second straight portion 32 of the bridge 26, as shown in Fig. 3. The pressure applicator 24 is located circumferentially between the strain gauges 34, 36.

[0055] In some embodiments, the biosensing unit 16 further includes a third strain gauge 38 and a fourth strain gauge 40, as shown in Fig. 3. The third strain gauge 38 is circumferentially spaced apart from the fourth strain gauge 40 about the axis 1 1 . The third and fourth strain gauges 38, 40 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 24 and the skin surface. The third strain gauge 38 is mounted to the first straight portion 30 of the bridge 26, and the fourth strain gauge 40 is mounted to the second straight portion 32 of the bridge 26. The third strain gauge 38 is located radially outward of the first strain gauge 34 relative to the axis 1 1 . The fourth strain gauge 40 is located radially outward of the second strain gauge 36 relative to the axis 11 . Though shown with one pressure applicator 24,one bridge 26, and four strain gauges 34, 36, 38, 40, any number of pressure applicators, bridges, and strain gauges are contemplated.

[0056] In some embodiments, the biosensing unit 16 further comprises an inertial sensor 46 (i.e. , an accelerometer or a gyroscope), as shown in Fig. 3. The inertial sensor 46 is configured to measure movement of the finger of the user (i.e., movement of the wearable biosensing system 10). In some embodiments, the biosensing unit 16 further comprises a photoplethysmography (PPG) sensor 48, as shown in Fig. 3. The PPG sensor 48 measures blood volume changes of the user. In some embodiments, the PPG sensor 48 is omitted. In some embodiments, the biosensing unit 16 further comprises temperature sensor(s) 53 for skin and ambient monitoring and / or air pressure sensor(s). For example, the biosensing unit 16 may include a skin temperature sensor 53 configured to measure skin temperature of the user. For example, the biosensing unit 16 may include an environmental temperature sensor 53 configured to measure a temperature of an environment around the user. In some embodiments, the biosensing unit 16 may include an electrocardiography (ECG) sensor 55 configured to measure electrical signal from the heart of the user.

[0057] In some embodiments, the wearable biosensing system 10 further includes a power unit 42 configured to provide power to electronics of the wearable biosensing system 10, as shown in Fig. 4. The power unit 42 includes a rechargeable battery 44 and an inductor charge coil 43 configured to wirelessly recharge the rechargeable battery 44. The power unit 42 is located in the interior space 20 of the ring frame 12. The power unit 42 may include a battery management device 45 that controls operation of the rechargeable battery 44, as shown in Fig. 3.

[0058] In some embodiments, the wearable biosensing system 10 further includes a controller 47, an analog-to-digital converter 49, and / or a communication module 51 , as shown in Fig. 3. The controller 47 may include a processor and / or a memory to store data and control operation of other components of the wearable biosensing system 10. The communication module 51 allows for wireless communication of the pressure data, the physiological signals, and / or the contact pressure to an external device, such as a smart watch, a smart phone, a tablet, a computer, the cloud, etc. The communication module 51 may comprise Bluetooth.

[0059] By using strain gauges 34, 36, 38, 40, blood pressure, heart rate, and / or heart rate variability, of the user may be determined without the use of a moretraditional biosensor. Further, knowing the contact pressure that is being applied to the skin surface is important as the signal may change as a function of the contact pressure. By looking at the signal acquisition as a function of or in relation to the contact pressure, the system 10 more accurately detects and / or monitors physiological signals and biomarkers.

[0060] Another embodiment of a wearable biosensing system 210 is shown in Figs. 5-12. The wearable biosensing system 210 is substantially similar to the wearable biosensing system 10 shown in Figs. 1-4 and described herein. Accordingly, similar reference numbers in the 200 series indicate features that are common between the wearable biosensing system 210 and the wearable biosensing system 10. The description of the wearable biosensing system 10 is incorporated by reference to apply to the wearable biosensing system 210, expect in instances when it conflicts with the specific description and the drawings of the wearable biosensing system 210.

[0061] The wearable biosensing system 210 includes a ring frame 212, a contact chassis 214, and a biosensing unit 216, as shown in Figs. 5-8. The ring frame 212 extends around an axis 211 to define a passageway 218 extending through the ring frame 212. The finger (or toe) of the user is received in the passageway 218. The contact chassis 214 is coupled to the ring frame 212 and configured to apply a contact pressure to skin surface of the user, for example, the skin surface of the finger. The biosensing unit 216 is coupled to the contact chassis 214 and configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the contact chassis 214 and the skin surface.

[0062] The ring frame 212 includes an inner wall 212I adapted to contact the skin surface of the user and an outer wall 2120 opposite the inner wall 2121, as shown in Fig. 6. The outer wall 2120 is located radially outward of the inner wall 212I relative to the axis 211 . The ring frame 212 defines an interior space 220 radially between the inner wall 212I and the outer wall 2120. The biosensing unit 216 and at least a portion of the contact chassis 214 are located in the interior space 220. The inner wall 212I may be formed to include an opening 222 that a portion of the contact chassis 214 extends through, as shown in Fig. 9. In some embodiments, the ring frame 212 is formed to include a wire-relief channel 250 that opens into the interior space 220 to allow any wires in the interior space 220 to extend out of the interior space 220, as shown in Fig. 7. In some embodiments, the wire-relief channel 250 may be omitted.

[0063] The contact chassis 214 includes a pressure applicator 224, a bridge 226, and a mount 228, as shown in Fig. 8. The pressure applicator 224 is coupled to the bridge 226 and extends from the interior space 220, through the opening 222 of the inner wall 212I, and into the passageway 218 of the ring frame 212. In this way, the pressure applicator 224 extends toward the axis 211 and toward the skin surface of the user to apply the contact pressure to the skin surface of the user. The bridge 226 extends circumferentially partway about the axis 21 1 in the interior space 220 of the ring frame 212. The mount 228 is coupled with the bridge 226 and the ring frame 212 to couple the contact chassis 214 to the ring frame 212.

[0064] The bridge 226 extends between a first end 226A and a second end 226B, as shown in Fig. 8. The pressure applicator 224 is located between and interconnects the first end 226A and the second end 226B. The bridge 226 is substantially straight, and at least a portion of the biosensing unit 216 is coupled to the bridge 226. The mount 228 is coupled to the bridge 226 and the ring frame 212, as shown in Figs. 8 and 9. The mount 228 is located in the interior space 220 of the ring frame 212.

[0065] As shown in Figs. 8 and 9, the contact chassis 214 is moveable relative to the ring frame 212 between an open position and a closed position. The contact chassis 214 may be moved to adjust a size of the system 210. It will be understood that the contact chassis 214 may be moved to different closed positions, and the closed position depends on the finger size of the user. In this way, the wearable biosensing system 210 may be fit to any user. While in the open position, as shown in Fig. 8, the pressure applicator 224 does not extend substantially into the passageway 218 of the ring frame 212. As shown in Fig. 9, while in the closed position, the pressure applicator 224 may extend into the passageway 218 of the ring frame 212 so that the system 210 fits tightly around the finger of the user. Once moved to the closed position, the pressure applicator 224 applies the contact pressure to the skin surface of the user. The movement of the contact chassis 214 may, thus, be used to control the contact pressure applied to the skin surface of the user.

[0066] In some embodiments, the contact chassis 214 includes a driver 252, as shown in Figs. 8 and 9. The driver 252 allows for movement of the contact chassis 214 relative to the ring frame 212. In some embodiments, the driver 252 includes a screw 254. The screw 254 extends through the outer wall 2120 of the ring frame 212 andinto a threaded hole 228H of the mount 228 of the contact chassis 214. The screw 254 may be rotated by the user to move the contact chassis 214. In some embodiments, the driver 252 may include a bearing 256, as shown in Figs. 8 and 9.

[0067] In some embodiments, the contact chassis 214 includes a shim 258, as shown in Fig. 10. The shim 258 may be positioned between the pressure applicator 224 and the inner wall 212I of the ring frame 212 after the pressure applicator 224 has reached its desired location (i.e., the contact chassis 214 is in the closed position). For example, the shim 258 may be coupled to the pressure applicator 224 via a screw extending through a shim mount hole 224H of the pressure applicator 224, as shown in Figs. 11 and 12. The contact chassis 214 allows for the system 210 to accommodate different finger sizes.

[0068] The biosensing unit 216 is mounted to the bridge 226 of the contact chassis 214 for movement therewith, as shown in Figs. 11 and 12. The biosensing unit 216 is located in the interior space 220 of the ring frame 212. The biosensing unit 216 illustratively includes a first strain gauge 234 and a second strain gauge 236 circumferentially spaced apart from the first strain gauge 234 about the axis 211. The first and second strain gauges 234, 236 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 224 and the skin surface. The first strain gauge 234 and the second strain gauge 236 are both mounted to the bridge 226 to locate the mount 228 therebetween.

[0069] In some embodiments, the biosensing unit 216 further includes a third strain gauge 238 and a fourth strain gauge 240, as shown in Figs. 11 and 12. The third strain gauge 238 is circumferentially spaced apart from the fourth strain gauge 240 about the axis 211 . The third and fourth strain gauges 238, 240 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 224 and the skin surface. The third strain gauge 238 and the fourth strain gauge 240 are mounted to the bridge 226 to locate the mount 228 therebetween. The third strain gauge 238 is located radially outward of the first strain gauge 234 relative to the axis 21 1 . The fourth strain gauge 240 is located radially outward of the second strain gauge 236 relative to the axis 211 .

[0070] Though shown with one pressure applicator 224, one bridge 226, and four strain gauges 234, 236, 238, 240, any number of pressure applicators, bridges, and strain gauges are contemplated.

[0071] Another embodiment of a wearable biosensing system 310 is shown in Figs. 13-15. The wearable biosensing system 310 is substantially similar to the wearable biosensing systems 10, 210. Accordingly, similar reference numbers in the 300 series indicate features that are common between the wearable biosensing system 310 and the wearable biosensing systems 10, 210. The description of the wearable biosensing systems 10, 210 is incorporated by reference to apply to the wearable biosensing system 310, expect in instances when it conflicts with the specific description and the drawings of the wearable biosensing system 310.

[0072] The wearable biosensing system 310 includes a ring frame 312, a contact chassis 314, and a biosensing unit 316, as shown in Figs. 13-15. The ring frame 312 extends around an axis 311 to define a passageway 318 extending through the ring frame 312. The finger (or toe) of the user is received in the passageway 318. The contact chassis 314 is coupled to the ring frame 312 and configured to apply a contact pressure to skin surface of the user, for example, the skin surface of the finger. The biosensing unit 316 is coupled to the contact chassis 314 and configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the contact chassis 314 and the skin surface.

[0073] The ring frame 312 includes an inner wall 312I adapted to contact the skin surface of the user and an outer wall 3120 opposite the inner wall 312I, as shown in Fig. 13. The outer wall 3120 is located radially outward of the inner wall 312I relative to the axis 311 . The ring frame 312 defines an interior space 320 radially between the inner wall 312I and the outer wall 3120. The biosensing unit 316 and at least a portion of the contact chassis 314 are located in the interior space 320. The inner wall 312I may be formed to include a plurality of openings 322 circumferentially spaced apart from one another about the axis 311 . A portion of the contact chassis 314 extends through the plurality of openings 322, as shown in Fig. 13. The size of the ring frame 312 (i.e., a diameter of the ring frame 312) may be adjusted to accommodate different finger or toe sizes.

[0074] In some embodiments, the ring frame 312 includes a top portion 312A and a bottom portion 312B, as shown in Fig. 14. The top portion 312A and the bottom portion 312B cooperate to define the interior space 320, as suggested in Fig. 14.

[0075] The contact chassis 314 includes a plurality of pressure applicators 324, a plurality of bridges 326, and a plurality of mounts 328, as shown in Fig. 14. Each of the pressure applicators 324 is coupled to a respective bridge 326 and extends from the interior space 320, through a respective opening 322 of the inner wall 3121, and into the passageway 318 of the ring frame 312. In this way, the pressure applicators 324 extend toward the axis 311 and the skin surface of the user to apply the contact pressure to the skin surface of the user. Each of the bridges 326 extends circumferentially partway about the axis 31 1 in the interior space 320 of the ring frame 312. Each of the mounts 328 is coupled with a respective bridge 326 and the ring frame 312 to fix the contact chassis 314 to the ring frame 312. The mounts 328 and the bridges 326 are located in the interior space 320 of the ring frame 312.

[0076] The pressure applicators 324 are spaced apart from one another circumferentially about the axis 311 , as shown in Fig. 13. In some embodiments, the plurality of pressure applicators 324 includes four pressure applicators 324, as shown in Figs. 13 and 14. However, any number of pressure applicators 324 is contemplated.

[0077] Each of the bridges 326 extends between a first end 326A and a second end 326B, as shown in Fig. 15. In some embodiments, each bridge 326 only extends partially circumferentially about the axis 311. In some embodiments, the plurality of bridges 326 cooperate to extend entirely circumferentially about the axis 311 , as shown in Fig. 14. In some embodiments, the plurality of bridges 326 includes four bridges 326, as shown in Fig. 14. However, any number of bridges 326 is contemplated.

[0078] Each of the pressure applicators 324 is coupled to a respective bridge 326 circumferentially between the first end 326A and the second end 326B of the respective bridge 326, as shown in Figs. 14 and 15. Each of the bridges 326 defines a first straight portion 330, a second straight portion 332 circumferentially spaced apart from the first straight portion 330, and a curved portion 335 extending between and interconnecting the first straight portion 330 and the second straight portion 332. Each of the pressure applicators 324 is coupled to the respective curved portion 335. At least part of the biosensing unit 316 is coupled to the first and second straight portions330, 332 of each of the plurality of bridges 326. In some embodiments, the straight portions 330, 332 may be curved such that each bridge 326 forms a continuous curve between the portions 330, 332, 335.

[0079] Each of the mounts 328 illustratively includes a first mount 328A coupled to the first end 326A of the respective bridge 326 and a second mount 328B coupled to the second end 326B of the respective bridge 326, as shown in Figs. 14 and 15. The first mount 328A and the second mount 328B are fixed to the ring frame 312. For example, in some embodiments, a plurality of screws 313 extend through the mounts 328A, 328B and into the bottom portion 312B of the ring frame 312, as suggested in Fig. 14. As shown in Fig. 14, the first mount 328A of one of the bridges 326 overlaps with the second mount 328B of an adjacent bridge 326, and one of the screws 313 extends through the first mount 328A and the second mount 328B to couple the two bridges 326 together. The plurality of mounts 328 overlap with one another around the ring frame 312 to form an annular bridge 326. However, in some embodiments, the plurality of mounts 328 may not overlap.

[0080] The biosensing unit 316 is mounted to the plurality of bridges 326 of the contact chassis 314, as shown in Fig. 14. The biosensing unit 316 is located in the interior space 320 of the ring frame 312. The biosensing unit 316 illustratively includes a plurality of strain gauges 334. In some embodiments, the plurality of strain gauges 334 includes sixteen strain gauges 334. A first portion of the plurality of strain gauges 334 are circumferentially spaced apart from one another about the axis 311 . A second portion of the plurality of strain gauges 334 are circumferentially spaced apart from one another about the axis 311 and radially spaced apart from the first portion of the plurality of strain gauges 334.

[0081] Though shown with four pressure applicators 324, four bridges 326, and sixteen strain gauges 334, any number of pressure applicators, bridges, and strain gauges are contemplated.

[0082] The plurality of strain gauges 334 is configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicators 324 and the skin surface. Two of the plurality of strain gauges 334 are mounted to the first straight portion 330 of each of the plurality of bridges 326, and two of the plurality of strain gauges 334 are mounted to the second straight portion 332 of each of the plurality of bridges 326, as shown inFigs. 14 and 15. In this way, the two strain gauges 334 on each of the first straight portions 330 are radially spaced apart from one another on opposing sides of the first straight portions 330, and the two strain gauges 334 on each of the second straight portions 332 are radially spaced apart from one another on opposing sides of the second straight portions 332.

[0083] Some of the strain gauges 334 may be configured to measure pressure data suitable for determining the physiological signals of the user and some of the strain gauges 334 may be configured to measure pressure data suitable for determining contact pressure developed between the contact chassis 314 and the skin surface. In this way, the strain gauges 334 used for contact pressure may compensate for noise, motion artifacts, and variations in the contact pressure that may impact the physiological signals measured by the other strain gauges 334. Contact pressure data may be associated or correlated with the physiological signal data to manage irregularities in the physiological signal data. The irregularities may be due to noise, motion artifacts, variations in contact pressure, pressure applicator placement, and / or individual anatomical differences between users. Thus, by associating the contact pressure data with the physiological signal data, the physiological signal data is improved and optimized.

[0084] In some embodiments, the wearable biosensing system 310 further includes a power unit 342 configured to provide power to electronics of the wearable biosensing system 310, as shown in Fig. 14. The power unit 342 includes a rechargeable battery 344 and an inductor charge coil 343 configured to wirelessly recharge the rechargeable battery 344. The power unit 342 is located in the interior space 320 of the ring frame 312.

[0085] In some embodiments, the wearable biosensing system 310 further includes a controller 347 and / or a communication module 351 , as shown in Fig. 14. The controller 347 may include a processor and / or a memory to store data and control operation of other components of the wearable biosensing system 310. The communication module 351 allows for wireless communication of the pressure data, the physiological signals, and / or the contact pressure to an external device, such as a smart watch, a smart phone, a tablet, a computer, the cloud, etc. The communication module 351 may comprise a 2.4 GHz antenna for Bluetooth.

[0086] Another embodiment of a contact chassis 314" for use with the wearable biosensing system 310 is shown in Fig. 16. The contact chassis 314" is substantially similar to the contact chassis 314. Accordingly, similar reference numbers with a double prime indicate features that are common between the contact chassis 314" and the contact chassis 314. The description of the contact chassis 314 is incorporated by reference to apply to the contact chassis 314", expect in instances when it conflicts with the specific description and the drawings of the contact chassis 314". As compared to the contact chassis 314, the contact chassis 314" has a different shaped bridge 326".

[0087] Another embodiment of a wearable biosensing system 310' is shown in Fig. 17. The wearable biosensing system 310' is substantially similar to the wearable biosensing systems 10, 210, 310. Accordingly, similar reference numbers in the 300 series with a prime symbol indicate features that are common between the wearable biosensing system 310' and the wearable biosensing systems 10, 210, 310. The description of the wearable biosensing systems 10, 210, 310 is incorporated by reference to apply to the wearable biosensing system 310', expect in instances when it conflicts with the specific description and the drawings of the wearable biosensing system 310'.

[0088] As compared to the wearable biosensing system 310, the wearable biosensing system 310' includes two contact chassis 314' stacked on top of one another, as suggested in Fig. 17. In this way, the wearable biosensing system 310' includes eight pressure applicators 324', eight bridges 326', and thirty-two strain gauges 334', as shown in Fig. 17. The wearable biosensing system 310' may include spacers 337' located between the mounts 328' of the two contact chassis 314'.

[0089] Another embodiment of a wearable biosensing system 410 is shown in Figs. 18-20. The wearable biosensing system 410 is substantially similar to the wearable biosensing systems 10, 210, 310, 310'. Accordingly, similar reference numbers in the 400 series indicate features that are common between the wearable biosensing system 410 and the wearable biosensing systems 10, 210, 310, 310’. The description of the wearable biosensing systems 10, 210, 310, 310' is incorporated by reference to apply to the wearable biosensing system 410, expect in instances when it conflicts with the specific description and the drawings of the wearable biosensing system 410.

[0090] The wearable biosensing system 410 includes a case 412, a contact chassis 414, and a biosensing unit 416, as shown in Figs. 18-20. Illustratively, the system 410 is a wearable device that may be worn around a wrist, a leg, an arm, etc. of the user. The case 412 is adapted to be coupled to the user via a strap 452, as shown in Figs. 18 and 19. For example, the strap 452 may extend through a strap buckle 470, as shown in Fig. 20. The contact chassis 414 is mounted for movement relative to the case 412 into contact with the skin surface of the user to apply a contact pressure to the skin surface of the user. The biosensing unit 416 is mounted to the contact chassis 414 for movement therewith relative to the case 412. The biosensing unit 416 is configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the contact chassis 414 and the skin surface.

[0091] The case 412 illustratively houses other components of the system 410 and includes a top wall 454 and a side wall 456 extending downwardly away from the top wall 454, as shown in Fig. 19. The side wall 456 defines a bottom surface 458 adapted to contact the skin surface of the user, as suggested in Fig. 19. The top wall 454 and the side wall 456 cooperate to define an interior space 420.

[0092] In some embodiments, the side wall 456 is formed to include a wire-relief channel 450 that opens into the interior space 420 to allow any wires in the interior space 420 to extend out of the interior space 420, as shown in Figs. 19 and 20. In some embodiments, the wire-relief channel 450 may be omitted.

[0093] In some embodiments, the case 412 further includes a flange 460 extending outwardly away from the side wall 456, as shown in Fig. 19. The flange 460 is adapted to contact the skin surface of the user. In some embodiments, the flange 460 may be omitted.

[0094] The contact chassis 414 includes a pressure applicator 424, a bridge 426, and a mount 428, as shown in Fig. 20. The pressure applicator 424 is coupled to the bridge 426 and extends toward the skin surface of the user to apply the contact pressure to the skin surface of the user. The bridge 426 is coupled with the biosensing unit 416. The mount 428 is coupled with the bridge 426 and the case 412.

[0095] The pressure applicator 424 extends downwardly beyond lower surfaces of the mount 428. In this way, the pressure applicator 424 contacts and applies the contact pressure to the skin surface of the user, while the mount 428 and the bridge426 are spaced apart from the skin surface of the user. The pressure applicator 424 may have any shape or size that allows the pressure applicator 424 to contact the skin surface.

[0096] The bridge 426 extends between and interconnects the pressure applicator 424 and the mount 428, as suggested in Fig. 20. Illustratively, the bridge 426 includes a first bridge 426A and a second bridge 426B, as shown in Fig. 20. The pressure applicator 424 is located between the bridges 426A, 426B. In some embodiments, a plurality of screws 413 couple the bridge 426 to the pressure applicator 424 and the mount 428. For example, one screw 413 extends through the bridge 426 and into the pressure applicator 424 to couple the pressure applicator 424 to the bridge 426.

[0097] The mount 428 is configured to be driven by a driver 462, as shown in Figs. 19 and 20, to move upwardly and downwardly relative to the top wall 454 of the case 412. The driver 462 moves the contact chassis 414 and the biosensing unit 416 relative to the case 412 to change the contact pressure applied by the pressure applicator 424 to the skin surface of the user.

[0098] The driver 462 is coupled with the top wall 454 of the case 412 and the mount 428 of the contact chassis 414 to selectively move the contact chassis 414 and the biosensing unit 416 relative to the case 412 to adjust the contact pressure applied to the skin surface of the user by the pressure applicator 424. The driver 462 illustratively includes a first driver 462A and a second driver 462B spaced apart from the first driver 462A, as shown in Fig. 20. The drivers 462A, 462B extend between the top wall 454 of the case 412 and the mount 428.

[0099] The first driver 462A extends through a first hole in the top wall 454 of the case 412 and into a first hole formed in the mount 428, as shown in Fig. 20. The second driver 462B extends through a second hole in the top wall 454 of the case 412 and into a second hole formed in the mount 428.

[0100] In some embodiments, the drivers 462A, 462B are each provided by a screw 464 extending through the top wall 454 of the case 412 and into the mount 428, a bearing 466, and / or a threaded insert 468, as shown in Fig. 20. The screws 464 rotate to move the contact chassis 414 relative to the case 412. In addition to using the driver 462, the strap 452 may be tightened or loosened to change the contact pressure applied to the skin surface of the user by the pressure applicator 424.

[0101] The biosensing unit 416 is mounted to the bridge 426 of the contact chassis 414, as suggested in Fig. 20. The biosensing unit 416 is located in the interior space 420 of the case 412. The biosensing unit 416 illustratively includes a first strain gauge 434 and a second strain gauge 436 spaced apart from the first strain gauge 434 to locate the pressure applicator 424 therebetween. The first and second strain gauges 434, 436 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 424 and the skin surface. The first strain gauge 434 and the second strain gauge 436 are mounted to a top wall of the bridge 426, as shown in Fig. 20.

[0102] In some embodiments, the biosensing unit 416 further includes a third strain gauge 438 and a fourth strain gauge 440 spaced apart from the third strain gauge 438 to locate the pressure applicator 424 therebetween, as shown in Fig. 20. The third and fourth strain gauges 438, 440 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 424 and the skin surface. The third and fourth strain gauges 438, 440 are mounted to a bottom wall of the bridge 426, as shown in Fig. 20.

[0103] Though shown with one pressure applicator 424, one bridge 426, and four strain gauges 434, 436, 438, 440, any number of pressure applicators, bridges, and strain gauges are contemplated.

[0104] In some embodiments, one or more of the strain gauges 434, 436, 438, 440 are configured to output pressure data suitable for determining the contact pressure developed between the pressure applicator 424 and the skin surface of the user. Based on the contact pressure and the physiological signal data, the contact pressure being applied to the skin surface by the pressure applicator 424 may be adjusted to manage / minimize motion artifacts or other irregularities in the physiological signal data.

[0105] In some embodiments, the system 10 further includes a controller 447, as shown in Fig. 18. The controller 447 is in communication with the strain gauges 434, 436, 438, 440 to receive pressure data therefrom. The controller 447 may include a memory, a processor, a communication module 451 , and / or a user interface. The controller 447 may use the pressure data to determine the contact pressure betweenthe pressure applicator 424 and the skin surface of the user and / or to determine the physiological signals. The controller 447 may associate the contact pressure developed between the pressure applicator 424 and the skin surface with the physiological signal data from the strain gauges 434, 436, 438, 440. The association of the contact pressure with the physiological signal data allows for the management of motion artifacts and other irregularities in the physiological signal data. In other words, the contact pressure is used to optimize and improve the physiological signal data.

[0106] For example, the pressure data is used to calculate, determine, and / or detect biological parameters and biomarkers within the physiological signal data that determine ailments and relative health states of the user. The contact pressure impacts the morphology of the physiological signals such that the contact pressure should be associated with and used when interpreting the physiological signal data. Thus, the contact pressure may be used to better show the user’s physiological state.

[0107] Biosensors that measure similar physiological events through different anatomical mediums are affected by contact pressure differently, which gives way to differential features that identify biomarkers when comparing two signals across a contact pressure gradient and / or when measuring at a single controlled contact pressure. Thus, the controller 447 accounts for the contact pressure when analyzing the physiological signal data for biomarkers. After associating the physiological signal data with the contact pressure, it may be determined that the biomarker detected is in fact a true biomarker, or it may be determined that the biomarker detected is an artifact due to the contact pressure variability (i.e., a false positive biomarker).

[0108] The controller 447 may use the contact pressure as an input for adjustments to operation of the driver 462. The controller 447 is configured to output an instruction associated with an optimized contact pressure to be implemented via adjustment of the driver 462. In some embodiments, the optimized contact pressure is based, at least in part, on a desired biomarker for identification or study. In some embodiments, the optimized contact pressure is based, at least in part, on the pressure data received from the strain gauges 434, 436, 438, 440.

[0109] The controller 447 may compare the contact pressure developed between the pressure applicator 424 and the skin surface with the optimized contact pressure to determine the instruction. For example, the pressure data from the strain gauges 434, 436, 438, 440 may indicate that the contact pressure applied to the userby the pressure applicator 424 is less (or more) than the optimized contact pressure for improved physiological signal data output from the strain gauges 434, 436, 438, 440. The controller 447 may analyze the physiological signal data to determine a level of noise in the data. If the level of noise is greater than a threshold, the instruction may indicate that the contact pressure should be adjusted to decrease the level of noise.

[0110] The instruction associated with the optimized contact pressure may be used for alignment of the contact pressure to the optimized contact pressure. For example, if the pressure data indicates that the contact pressure applied to the user by the pressure applicator 424 is less than desirable, the instruction may indicate that the contact pressure should be increased so that the contact pressure aligns with the optimized contact pressure. To align the contact pressure with the optimized contact pressure, the driver 462 drives the mount 428 away from the top wall 454 of the case 412 to increase the contact pressure between the pressure applicator 424 and the user.

[0111] The controller 447 is configured to output the instruction associated with the optimized contact pressure to the user interface so that the user is informed of the instruction associated with the optimized contact pressure. Based on the instruction, the user may manually adjust the driver 462. The user interface may form a part of a smart watch, a smart phone, a tablet, a computer, etc.

[0112] In some embodiments, the controller 447 is in communication with the driver 462 to provide for automatic adjustment of the contact chassis 414 via the driver 462 without user involvement. The controller 447 is configured to communicate the instruction associated with the optimized contact pressure to the driver 462. Based on the instruction, the driver 462 moves the contact chassis 414. The driver 462 is configured to provide infinitely variable adjustment of the contact chassis 414 so that the contact pressure matches the optimized contact pressure.

[0113] In some embodiments, the biosensing unit 416 further comprises a photoplethysmography (PPG) sensor 448, as shown in Fig. 20. The PPG sensor 448 measures blood volume changes of the user. In some embodiments, the PPG sensor 448 is omitted. In some embodiments, the biosensing unit 416 further comprises an electrocardiography (ECG) sensor that measures the electrical signal when the subject touches the case 412 with the other hand. In some embodiments, the biosensing unit 416 further comprises a temperature sensor that measures the skin surfacetemperature. In some embodiments, the biosensing unit 416 further comprises a temperature sensor that measures the ambient temperature.

[0114] Another embodiment of a wearable biosensing system 510 is shown in Figs. 21 -23. The wearable biosensing system 510 is substantially similar to the wearable biosensing systems 10, 210, 310, 310', 410. Accordingly, similar reference numbers in the 500 series indicate features that are common between the wearable biosensing system 510 and the wearable biosensing systems 10, 210, 310, 310', 410. The description of the wearable biosensing systems 10, 210, 310, 31 O', 410 is incorporated by reference to apply to the wearable biosensing system 510, expect in instances when it conflicts with the specific description and the drawings of the wearable biosensing system 510.

[0115] The wearable biosensing system 510 includes a case 512, a contact chassis 514, and a biosensing unit 516, as shown in Figs. 22 and 23. Illustratively, the system 510 is a wearable device that may be coupled to a wrist, a leg, an arm, etc. of a user. The case 512 is adapted to be coupled to the user via a strap 552, as shown in Fig. 21 . The contact chassis 514 contacts the skin surface of the user to apply a contact pressure to the skin surface of the user. The biosensing unit 516 is mounted to the contact chassis 514 and configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the contact chassis 514 and the skin surface.

[0116] The case 512 illustratively houses other components of the system 510 and includes a top wall 554, a side wall 556 extending downwardly away from the top wall 554, and a bottom wall 557, as shown in Fig. 22. The top wall 554, the side wall 556, and the bottom wall 557 cooperate to define an interior space 520. The top wall 554 and a portion of the side wall 556 define a top portion of the case 512, and another portion of the side wall 556 and the bottom wall 557 define a bottom portion of the case 512, as shown in Fig. 23

[0117] The contact chassis 514 includes a plurality of pressure applicators 524, a plurality of bridges 526, and a mount 528, as shown in Fig. 23. The pressure applicators 524 are coupled to the bridges 526 and extend toward the skin surface of the user to apply the contact pressure to the skin surface of the user. The bridges 526 are coupled with the biosensing unit 516. The mount 528 is coupled with the bridges 526 to support the bridges 526 relative to the case 512.

[0118] Illustratively, the plurality of bridges 526 includes a first bridge 526A, a second bridge 526B, a third bridge 526C, a fourth bridge 526D, and a fifth bridge 526E, as shown in Fig. 23. Each of the bridges 526 is coupled to the mount 528. The first bridge 526A, the second bridge 526B, the third bridge 526C, and the fourth bridge 526D may be mounted to the mount 528 so as to form a rectangular shape.

[0119] The plurality of pressure applicators 524 includes a first pressure applicator 524A, a second pressure applicator 524B, a third pressure applicator 524C, a fourth pressure applicator 524D, and a fifth pressure applicator 524E, as shown in Fig. 23. Each of the pressure applicators 524 is coupled to a respective bridge 526. For example, the first pressure applicator 524A is coupled to the first bridge 526A via a fastener. The first pressure applicator 524A extends through a hole formed in the bottom wall 557 of the case 512 to contact the skin surface of the user. In this way, the pressure applicators 524 contact and apply the contact pressure to the skin surface of the user, while the mount 528 and the bridges 526 are spaced apart from the skin surface of the user.

[0120] Each of the bridges 526 is coupled with the mount 528, as suggested in Fig. 23. For example, fasteners may extend through holes of the mount 528 and into holes of the bridges 526. The bridges 526 are located below the mount 528, and the pressure applicators 524 are located below the bridges 526.

[0121] The biosensing unit 516 is mounted to the bridges 526 of the contact chassis 514, as suggested in Fig. 23. The biosensing unit 516 illustratively includes a plurality of strain gauges 534 configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicators 524 and the skin surface. Each of the bridges 526 has four strain gauges 534 mounted thereto. As shown in Fig. 23, two strain gauges 534 are mounted to a top wall of each bridge 526, and two strain gauges 534 are mounted to a bottom wall of each bridge 526.

[0122] Though shown with five pressure applicators 524, five bridges 526, and twenty strain gauges 534, any number of pressure applicators, bridges, and strain gauges are contemplated.

[0123] In some embodiments, the biosensing unit 516 further comprises a photoplethysmography (PPG) sensor 548, as shown in Fig. 23. The PPG sensor 548 measures blood volume changes of the user. The PPG sensor 548 is mounted to thepressure applicator 524E, which is mounted to the bridge 526E. The bridge 526E is located between the bridges 526A, 526B, 526C, 526D. In some embodiments, the biosensing unit 516 further comprises a temperature sensor that measures the skin surface temperature. In some embodiments, the biosensing unit 516 further comprises a temperature sensor that measures the ambient temperature.

[0124] In some embodiments, the system 510 is strapped to the user so that the third, fourth, and fifth pressure applicators 524C, 524D, 524E are overlying or aligned along an artery of the user. In this way, the strain gauges 534 coupled to the third bridge 526C and the fourth bridge 526D may measure pressure data suitable for determining physiological signals of the user and the strain gauges 534 coupled to the first bridge 526A and the second bridge 526B may measure pressure data suitable for determining the contact pressure developed between the pressure applicators 524A, 524B and the skin surface of the user.

[0125] The strain gauges 534 coupled to the third bridge 526C and the fourth bridge 526D may be referred to as main strain gauges, while the strain gauges 534 coupled to the third bridge 526C and the fourth bridge 526D may be referred to as compensation strain gauges or reference strain gauges. The compensation strain gauges compensate for noise, motion artifacts, and variations in the contact pressure that may impact the physiological signals measured by the main strain gauges. For example, movement of the user may result in noise or motion artifacts in physiological signal data from the main strain gauges. Contact pressure data from the compensation strain gauges may be associated or correlated with the physiological signal data to manage irregularities in the physiological signal data. The irregularities may be due to noise, motion artifacts, variations in contact pressure, pressure applicator placement, and / or individual anatomical differences between users. Thus, by associating the contact pressure data with the physiological signal data, the physiological signal data is improved and optimized.

[0126] In some embodiments, the wearable biosensing system 510 further includes an inductor charge coil 543 and a rechargeable battery 544 configured to provide power to electronics of the wearable biosensing system 510, as shown in Fig. 23. The rechargeable battery 544 is located in the interior space 520 of the case 512.

[0127] In some embodiments, the wearable biosensing system 510 further includes a controller 547, a communication module 551 , and / or an inertial sensor 546,as shown in Fig. 23. The controller 547 may include a processor and / or a memory to control operation of other components of the wearable biosensing system 510. The controller 547 may associate the contact pressure data with the physiological signal data. The communication module 551 allows for wireless communication of the pressure data, the physiological signals, and / or the contact pressure to an external device, such as a smart watch, a smart phone, a tablet, a computer, the cloud, etc. The communication module 551 may comprise Bluetooth.

[0128] In some embodiments, the system 510 may further include a plurality of ECG electrodes 580 coupled to the strap 552 in spaced apart relation to one another, as shown in Fig. 21 . The ECG electrodes 580 measure electrical signals, such as single-sided ECG, from the heart of the user.

[0129] Another embodiment of a wearable biosensing system 610 is shown in Figs. 24-26. The wearable biosensing system 510 is substantially similar to the wearable biosensing systems 10, 210, 310, 310', 410, 510. Accordingly, similar reference numbers in the 600 series indicate features that are common between the wearable biosensing system 610 and the wearable biosensing systems 10, 210, 310, 31 O', 410, 510. The description of the wearable biosensing systems 10, 210, 310, 31 O', 410, 510 is incorporated by reference to apply to the wearable biosensing system 610, expect in instances when it conflicts with the specific description and the drawings of the wearable biosensing system 610.

[0130] The wearable biosensing system 610 includes a case 612, a contact chassis 614, and a biosensing unit 616, as shown in Figs. 25 and 26. Illustratively, the system 610 is a wearable device that may be worn on a chest, a wrist, a leg, an arm, etc. of a user. The case 612 is adapted to be coupled to the user via an adhesive material 652, as shown in Fig. 25. The contact chassis 614 is mounted for movement relative to the case 612 into contact with the skin surface of the user to apply a contact pressure to the skin surface of the user. The biosensing unit 616 is mounted to the contact chassis 614 for movement therewith relative to the case 612. The biosensing unit 616 is configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the contact chassis 614 and the skin surface.

[0131] The case 612 illustratively houses other components of the system 610 and includes a top wall 654 and a side wall 656 extending downwardly away from thetop wall 654, as shown in Fig. 25. The side wall 656 defines a bottom surface 658 adapted to contact the skin surface of the user, as suggested in Fig. 26. The top wall 654 and the side wall 656 cooperate to define an interior space 620.

[0132] In some embodiments, the case 612 further includes a flange 660 extending outwardly away from the side wall 656, as shown in Figs. 25 and 26. The flange 660 is adapted to contact the skin surface of the user. In some embodiments, the flange 660 may be omitted.

[0133] The adhesive material 652 is configured to adhere the case 612 to the skin surface of the user, as suggested in Fig. 24. In some embodiments, the adhesive material 652 is provided by tape that overlaps with the flange 660 of the case 612 to contact the flange 660 of the case 612 and the skin surface of the user. In some embodiments, the adhesive material 652 is provided by double-sided tape. The double-sided tape may be provided on the bottom surface 658 of the side wall 656, for example, in embodiments in which the flange 660 is omitted, or on a bottom surface of the flange 660 and / or the bottom surface 658 of the side wall 656.

[0134] The contact chassis 614 includes a pressure applicator 624, a bridge 626, and a mount 628, as shown in Fig. 26. The pressure applicator 624 is coupled to the bridge 626 and extends toward the skin surface of the user to apply the contact pressure to the skin surface of the user. The bridge 626 is coupled with the biosensing unit 616. The mount 628 is coupled with the bridge 626 and the case 612.

[0135] The pressure applicator 624 extends downwardly beyond a lower surface of the mount 628. In this way, the pressure applicator 624 contacts and applies the contact pressure to the skin surface of the user, while the mount 628 and the bridge 626 are spaced apart from the skin surface of the user. The pressure applicator 624 may have any shape or size that allows the pressure applicator 624 to contact the skin surface.

[0136] The bridge 626 extends between and interconnects the pressure applicator 624 and the mount 628, as suggested in Fig. 26. Illustratively, the bridge 626 includes a first bridge 626A and a second bridge 626B, as shown in Fig. 26. The pressure applicator 624 is located between the bridges 626A, 626B. In some embodiments, a plurality of screws 613 coupled the bridge 626 to the pressure applicator 624 and the mount 628. For example, one of the screws 613 extendsthrough the bridge 626 and into the pressure applicator 624 to couple the pressure applicator 624 to the bridge 626.

[0137] The mount 628 is configured to be driven by a driver 662 to move upwardly and downwardly relative to the top wall 654 of the case 612. The driver 662 moves the contact chassis 614 and the biosensing unit 616 relative to the case 612 to change the contact pressure applied by the pressure applicator 624 to the skin surface of the user.

[0138] The driver 662 is coupled with the top wall 654 of the case 612 and the mount 628 of the contact chassis 614 to selectively move the contact chassis 614 and the biosensing unit 616 relative to the case 612 to adjust the contact pressure applied to the skin surface of the user by the pressure applicator 624. The driver 662 illustratively includes a first driver 662A and a second driver 662B spaced apart from the first driver 662A. The drivers 662A, 662B extend between the top wall 654 of the case 612 and the mount 628.

[0139] The first driver 662A extends through a first hole in the top wall 654 of the case 612 and into a first hole formed in the mount 628, as suggested in Fig. 26. The second driver 662B extends through a second hole in the top wall 654 of the case 612 and into a second hole formed in the mount 628.

[0140] In some embodiments, the drivers 662A, 662B are each provided by a screw 664 extending through the top wall 654 of the case 612 and into the mount 628, a bearing 666, and / or a threaded insert 668. The screws 664 rotate to move the contact chassis 614 relative to the case 612.

[0141] The biosensing unit 616 is mounted to the bridge 626 of the contact chassis 614, as suggested in Fig. 26. The biosensing unit 616 is located in the interior space 620 of the case 612. The biosensing unit 616 illustratively includes a first strain gauge 634 and a second strain gauge 636 spaced apart from the first strain gauge 634 to locate the pressure applicator 624 therebetween. The first and second strain gauges 634, 636 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 624 and the skin surface. The first strain gauge 634 and the second strain gauge 636 are mounted to a top surface of the bridge 626, as shown in Fig. 23.

[0142] In some embodiments, the biosensing unit 616 further includes a third strain gauge 638 and a fourth strain gauge 640 spaced apart from the third strain gauge 638 to locate the pressure applicator 624 therebetween, as shown in Fig. 26. The third and fourth strain gauges 638, 640 are configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicator 624 and the skin surface. The third and fourth strain gauges 638, 640 are mounted to a bottom surface of the bridge 626, as shown in Fig. 26.

[0143] Though shown with one pressure applicator 624, one bridge 626, and four strain gauges 634, any number of pressure applicators, bridges, and strain gauges are contemplated.

[0144] In some embodiments, one or more of the strain gauges 634, 636, 638, 640 are configured to output pressure data suitable for determining the contact pressure developed between the pressure applicator 624 and the skin surface of the user. Based on the contact pressure and the physiological signal data, the contact pressure being applied to the skin surface by the pressure applicator 624 may be adjusted to manage / minimize motion artifacts or other irregularities in the physiological signal data.

[0145] In some embodiments, the system 10 further includes a controller 647, as shown in Fig. 23. The controller 647 is in communication with the strain gauges 634, 636, 638, 640 to receive pressure data therefrom. The controller 647 may use the pressure data to determine the contact pressure between the pressure applicator 624 and the skin surface of the user. The controller 647 may associate the contact pressure developed between the pressure applicator 624 and the skin surface with the physiological signal data from the strain gauges 634, 636, 638, 640. The controller 647 may use the contact pressure as an input for adjustments to operation of the driver 662.

[0146] In some embodiments, the biosensing unit 616 further comprises a photoplethysmography (PPG) sensor 648, as shown in Fig. 26. The PPG sensor 648 measures blood volume changes of the user. In some embodiments, the PPG sensor 648 may be omitted. In some embodiments, the biosensing unit 616 further comprises an electrocardiography (ECG) sensor that measures the electrical signal from the heart. In some embodiments, the biosensing unit 616 further comprises a temperaturesensor that measures the skin surface temperature. In some embodiments, the biosensing unit 616 further comprises a temperature sensor that measures the ambient temperature.

[0147] In some embodiments, the biosensing unit 616 further comprises an inertial sensor 646, as shown in Fig. 26. The inertial sensor 646 is configured to measure movement of the user (i.e., movement of the wearable biosensing system 610).

[0148] In some embodiments, the wearable biosensing system 610 further includes a power unit 642 configured to provide power to electronics of the wearable biosensing system 610, as shown in Fig. 26. The power unit 642 includes a rechargeable battery 644 and an inductor charge coil 643 configured to wirelessly recharge the rechargeable battery 644. The power unit 642 is located in the interior space 620 of the case 612. The power unit 642 may include a battery management device 645 that controls operation of the rechargeable battery 644, as shown in Fig. 26.

[0149] In some embodiments, the wearable biosensing system 610 further includes an analog-to-digital converter 649 and / or a communication module 651 , as shown in Fig. 26. The communication module 651 allows for wireless communication of the pressure data, the physiological signals, and / or the contact pressure to an external device, such as a smart watch, a smart phone, a tablet, a computer, the cloud, etc. The communication module 651 may comprise Bluetooth.

[0150] Another embodiment of a wearable biosensing system 710 is shown in Figs. 27-29. The wearable biosensing system 710 is substantially similar to the wearable biosensing systems 10, 210, 310, 310', 410, 510, 610. Accordingly, similar reference numbers in the 700 series indicate features that are common between the wearable biosensing system 710 and the wearable biosensing systems 10, 210, 310, 31 O', 410, 510, 610. The description of the wearable biosensing systems 10, 210, 310, 31 O', 410, 510, 610 is incorporated by reference to apply to the wearable biosensing system 710, expect in instances when it conflicts with the specific description and the drawings of the wearable biosensing system 710.

[0151] The wearable biosensing system 710 includes a case 712, a contact chassis 714, and a biosensing unit 716, as shown in Figs. 27-29. Illustratively, the system 710 is a wearable device that may be coupled to a wrist, a leg, an arm, etc. of auser with a strap or may be adhered to a chest, a wrist, a leg, an arm, etc. of the user with an adhesive material. The case 712 is adapted to be coupled to the user. The contact chassis 714 contacts the skin surface of the user to apply a contact pressure to the skin surface of the user. The biosensing unit 716 is mounted to the contact chassis 714 and configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the contact chassis 714 and the skin surface.

[0152] The case 712 illustratively houses other components of the system 710 and includes a top wall 754, a side wall 756 extending downwardly away from the top wall 754, and a bottom wall 757, as shown in Fig. 27. The top wall 754, the side wall 756, and the bottom wall 757 cooperate to define an interior space 720. The top wall 754 and a portion of the side wall 756 define a top portion of the case 712, and another portion of the side wall 756 and the bottom wall 757 define a bottom portion of the case 712, as shown in Fig. 28.

[0153] The contact chassis 714 includes a plurality of pressure applicators 724, a plurality of bridges 726, and a mount 728, as shown in Fig. 28. Each of the pressure applicators 724 is coupled to a respective bridge 726 and extends toward the skin surface of the user to apply the contact pressure to the skin surface of the user. The bridges 726 are coupled with the biosensing unit 716. The mount 728 is coupled with the bridges 726 to support the bridges 726 relative to the case 712.

[0154] Illustratively, the plurality of bridges 726 includes a first bridge 726A, a second bridge 726B, a third bridge, and a fourth bridge, as shown in Figs. 28 and 29. The second bridge 726B, the third bridge, and the fourth bridge are identical.

[0155] The plurality of pressure applicators 724 includes a first pressure applicator 724A, a second pressure applicator 724B, a third pressure applicator 724C, and a fourth pressure applicator 724D, as shown in Fig. 28. Each of the pressure applicators 724 is coupled to a respective bridge 726. For example, the first pressure applicator 724A is coupled with the first bridge 726A via one or more fasteners that extend through holes of the first bridge 726A and into the first pressure applicator 724A. The second pressure applicator 724B is coupled with the second bridge 726B via a fastener that extends through a hole of the second bridge 726B and into the second pressure applicator 724B. The third pressure applicator 724C is coupled with the third bridge via a fastener that extends through a hole of the third bridge and intothe third pressure applicator 724C. The fourth pressure applicator 724D is coupled with the fourth bridge via a fastener that extends through a hole of the fourth bridge and into the fourth pressure applicator 724D. As previously mentioned, the second bridge 726B, the third bridge, and the fourth bridge are identical.

[0156] The first pressure applicator 724A extends through a hole formed in the bottom wall 757 of the case 712 to contact the skin surface of the user, as shown in Fig. 27. The first pressure applicator 724A may be located at a center point of the bottom wall 757. The second, third, and fourth pressure applicators 724B, 724C, 724D may extend through respective holes formed in the bottom wall 757 of the case 712 so that the second, third, and fourth pressure applicators 724B, 724C, 724D are circumferentially spaced apart from one another around the first pressure applicator 724A. Each of the pressure applicators 724 contacts and applies the contact pressure to the skin surface of the user, while the mount 728 and the bridges 726 are spaced apart from the skin surface of the user.

[0157] Each of the bridges 726 is coupled with the mount 728, as suggested in Fig. 28. For example, fasteners may extend through holes of the bridges 726 and into holes of the mount 728.

[0158] The biosensing unit 716 is mounted to the bridges 726 of the contact chassis 714, as suggested in Fig. 28. The biosensing unit 716 illustratively includes a plurality of strain gauges 734 configured to measure pressure data suitable for determining the physiological signals of the user and / or contact pressure developed between the pressure applicators 724 and the skin surface. Each bridge 726 has four strain gauges 734 mounted thereto. As shown in Figs. 28 and 29, two strain gauges 734 are mounted to a top surface of each bridge 726, and two strain gauges 734 are mounted to a bottom surface of each bridge 726.

[0159] Though shown with four pressure applicators 724, four bridges 726, and sixteen strain gauges 734, any number of pressure applicators, bridges, and strain gauges are contemplated.

[0160] In some embodiments, the biosensing unit 716 further comprises a photoplethysmography (PPG) sensor 748, as shown in Figs. 27 and 28. The PPG sensor 748 measures blood volume changes of the user. The PPG sensor 748 is mounted to the pressure applicator 724A, which is mounted to the bridge 726A.

[0161] In some embodiments, the biosensing unit 716 further comprises an electrocardiography (ECG) sensor that measures the electrical signal. In some embodiments, the biosensing unit 716 further comprises a temperature sensor that measures the skin surface temperature. In some embodiments, the biosensing unit 716 further comprises a temperature sensor that measures the ambient temperature.

[0162] In some embodiments, the system 710 is strapped or adhered to the user so that the first pressure applicator 724A overlies or is aligned with an artery of the user. In this way, the strain gauges 734 coupled to the first bridge 726A may measure pressure data suitable for determining physiological signals of the user, and the strain gauges 734 coupled to the second, third, and fourth bridges 726B may measure pressure data suitable for determining the contact pressure developed between the pressure applicators 724B, 724C, 724D and the skin surface of the user.

[0163] The strain gauges 734 coupled to the first bridge 726A may be referred to as main strain gauges, while the strain gauges 734 coupled to the second, third, and fourth bridges 726B may be referred to as compensation strain gauges or reference strain gauges. The compensation strain gauges compensate for noise, motion artifacts, and variations in the contact pressure that may impact the physiological signals measured by the main strain gauges. Contact pressure data from the compensation strain gauges may be associated or correlated with the physiological signal data to manage irregularities in the physiological signal data. Thus, by associating the contact pressure data with the physiological signal data, the physiological signal data is improved and optimized.

[0164] In some embodiments, the wearable biosensing system 710 further includes a controller 747 and / or a communication module 751 , as shown in Fig. 28. The controller 747 may include a processor and / or a memory to store data and control operation of other components of the wearable biosensing system 710. The controller 747 may associate the contact pressure data with the physiological signal data. The communication module 751 allows for wireless communication of the pressure data, the physiological signals, and / or the contact pressure to an external device, such as a smart watch, a smart phone, a tablet, a computer, the cloud, etc. The communication module 751 may comprise Bluetooth.

[0165] In some embodiments, the system 710 further includes a power unit 742 having an inductor charge coil and a rechargeable battery and / or an inertial sensor 746, as shown in Fig. 28.

[0166] In some embodiments, the system 710 may further includes a plurality of electrodes 780 coupled to the bottom wall 757 circumferentially spaced apart from one another, as shown in Fig. 27. The electrodes 780 may be circumferentially offset from the pressure applicators 724B, 724C, 724D.

[0167] As shown in Figs. 30 and 31 , the systems 10, 210, 310, 310', 410, 510, 610, 710 may be located at multiple different locations on the body of the user.Exemplary locations are shown in Figs. 30 and 31 . As shown in Fig. 30, the system 10, 210, 310, 310' may extend around a toe of the user. As shown in Fig. 30, the system 410, 510, 610, 710 may be coupled to a leg of the user via a strap or via an adhesive material. As shown in Fig. 31 , the system 410, 510, 610, 710 may be coupled to an arm of the user via a strap or via an adhesive material.

[0168] Fig. 32 shows a pressure waveform generation using one of the systems 10, 210, 310, 31 O', 410, 510, 610, 710 where blood pressure can be extrapolated from. Fig. 33 shows a positive correlation between a typical continuous blood pressure monitoring device (X-axis) and one of the systems 10, 210, 310, 31 O', 410, 510, 610, 710 (Y-axis). Fig. 34 shows the cyclical pressure wave morphology from one of the systems 10, 210, 310, 31 O', 410, 510, 610, 710. Fig. 34 also shows features of the morphology and their association with the cardiac cycle.

[0169] The systems 10, 210, 310, 310', 410, 510, 610, 710 continuously monitor cardiac features, such as, but not limited to, blood pressure, cardiac pulse wave morphology, heart rate, heart rate variability, respiration rate, and body systemic pressure. The form factor serves as a foundation for a method of acquisition that users can use with comfort throughout the day. Cardiac features can be monitored to reveal early heart disease, cardiac arrhythmias, the onset of hypo / hyperglycemic events, the development of peripheral artery disease, blood clots, and other events, such as the early onset of a seizure as well as to differentiate white coat hypertension and masked hypertension from other hypertensive and hypotensive states. Additional sensors in the systems 10, 210, 310, 31 O', 410, 510, 610, 710 can include temperature sensors for skin and ambient monitoring, an accelerometer, a gyroscope, an electrocardiogram, anair pressure sensor, an optical sensor, including a pulse oximeter and / or a photoplethysmography sensor, or any combination thereof.

[0170] The algorithm for the pressure includes a calibration curve generated from applying weights to the contact interface, measuring the ADC response, and extrapolating a calibration curve. The known contact pressure is then multiplied by a response variable to get systolic and diastolic blood pressure and the full morphological readout of the systemic blood pressure over time as a function of the cardiac cycle. The data is then actively sent off the system 10, 210, 310, 31 O', 410, 510, 610, 710 using Bluetooth communication, for example. The data can be stored on a device using a mass storage device, which can then be uploaded to a local device at a later time.

[0171] Devices today do not directly measure continuous blood pressure accurately and typically use multimodal systems that involve photoplethysmography and bioimpedance or require a cuff, bladder, or some form of secondary control to generate controlled parameters compatible with a narrow margin algorithm. These devices are cumbersome and, due to the complexity of their nature, are also expensive. The systems 10, 210, 310, 31 O', 410, 510, 610, 710, which include pressure transducers (i.e., pressure applicators), allows the systems 10, 210, 310, 31 O', 410, 510, 610, 710 to quantify blood pressure and other cardiac features directly at a fraction of the cost and with greater accuracy, making the systems 10, 210, 310, 31 O', 410, 510, 610, 710 more accessible to all populations and demographics.

[0172] Any number of pressure applicators attached to any number of bridges, which contain any number of strain gauges is contemplated. For example, pressure signals may be measured from one to twenty pressure applicators and / or from one to forty strain gauges.

[0173] The systems 10, 210, 310, 310', 410, 510, 610, 710 use a mechanical design to control contact force, which is then directed to the bridge. The bridge has a pressure transducer, such as a full or half bridge strain gauge arrangement, that quantifies the strain. This strain can be linearly correlated with contact pressure and pressure response, which allows the systems 10, 210, 310, 310', 410, 510, 610, 710 to measure blood pressure and cardiac differential fluid flow morphology directly.

[0174] The following numbered clauses include embodiments that are contemplated and non-limiting:

[0175] Clause 1 . A wearable biosensing system comprising a ring frame extending around an axis to define a passageway to receive a finger of a user therein, the ring frame including an inner wall adapted to contact a skin surface of the finger and an outer wall opposite the inner wall, the ring frame defining an interior space radially between the inner wall and the outer wall; a contact chassis including a pressure applicator configured to extend from the interior space of the ring frame through the inner wall toward the axis and into contact with the skin surface to apply a contact pressure to the skin surface and a bridge fixed to the ring frame and located in the interior space of the ring frame; and a biosensing unit mounted to the bridge of the contact chassis and located in the interior space of the ring frame, the biosensing unit including a first strain gauge and a second strain gauge circumferentially spaced apart from the first strain gauge about the axis, the first and second strain gauges configured to measure pressure data suitable for determining physiological signals of the user.

[0176] Clause 2. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge and the second strain gauge are spaced apart circumferentially about the ring frame to locate the pressure applicator therebetween.

[0177] Clause 3. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the bridge includes a first straight portion, a second straight portion circumferentially spaced apart from the first straight portion, and a curved portion extending between and interconnecting the first straight portion and the second straight portion.

[0178] Clause 4. The wearable biosensing system of clause 3, any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge is mounted to the first straight portion.

[0179] Clause 5. The wearable biosensing system of clause 4, any other suitable clause, or any other suitable combination of clauses, wherein the second strain gauge is mounted to the second straight portion.

[0180] Clause 6. The wearable biosensing system of clause 5, any other suitable clause, or any other suitable combination of clauses, wherein the pressure applicator is coupled to the curved portion.

[0181] Clause 7. The wearable biosensing system of clause 3, any other suitable clause, or any other suitable combination of clauses, wherein the biosensingunit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

[0182] Clause 8. The wearable biosensing system of clause 7, any other suitable clause, or any other suitable combination of clauses, wherein the third strain gauge is mounted to the first straight portion of the bridge and the fourth strain gauge is mounted to the second straight portion of the bridge.

[0183] Clause 9. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

[0184] Clause 10. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises an inertial sensor configured to measure movement of the finger of the user.

[0185] Clause 11 . The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises a photoplethysmography (PPG) sensor configured to measure blood volume changes of the user.

[0186] Clause 12. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises an electrocardiography (ECG) sensor configured to measure electrical signal from a heart of the user.

[0187] Clause 13. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises a skin temperature sensor configured to measure skin temperature of the user.

[0188] Clause 14. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises an environmental temperature sensor configured to measure a temperature of an environment around the user.

[0189] Clause 15. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, further comprising a power unit configured to provide power to electronics of the wearable biosensingsystem, the power unit includes a rechargeable battery and an inductor charge coil configured to wirelessly recharge the rechargeable battery.

[0190] Clause 16. The wearable biosensing system of clause 15, any other suitable clause, or any other suitable combination of clauses, wherein the power unit is located in the interior space of the ring frame.

[0191] Clause 17. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the bridge extends only partially circumferentially about the ring frame.

[0192] Clause 18. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the bridge extends between a first end and a second end thereof opposite the first end, and wherein the first end and the second end of the bridge are fixed to the ring frame.

[0193] Clause 19. The wearable biosensing system of clause 18, any other suitable clause, or any other suitable combination of clauses, wherein the pressure applicator is located circumferentially between the first end and the second end of the bridge about the ring frame.

[0194] Clause 20. The wearable biosensing system of clause 19, any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge is located circumferentially between the first end of the bridge and the pressure applicator and the second strain gauge is located circumferentially between the pressure applicator and the second end of the bridge.

[0195] Clause 21 . The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the bridge extends entirely circumferentially about the ring frame.

[0196] Clause 22. The wearable biosensing system of clause 1 , any other suitable clause, or any other suitable combination of clauses, wherein the pressure applicator is a first pressure applicator, and wherein the contact chassis further includes a second pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

[0197] Clause 23. The wearable biosensing system of clause 22, any other suitable clause, or any other suitable combination of clauses, wherein the second pressure applicator is circumferentially spaced apart from the first pressure applicator.

[0198] Clause 24. The wearable biosensing system of clause 22, any other suitable clause, or any other suitable combination of clauses, wherein the contact chassis further includes a third pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis and a fourth pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

[0199] Clause 25. The wearable biosensing system of clause 24, any other suitable clause, or any other suitable combination of clauses, wherein the first, second, third, and fourth pressure applicators are circumferentially spaced apart from one another about the axis.

[0200] Clause 26. The wearable biosensing system of clause 24, any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge is located circumferentially between the first pressure applicator and the fourth pressure applicator, and wherein the second strain gauge is located circumferentially between the first pressure applicator and the second pressure applicator.

[0201] Clause 27. The wearable biosensing system of clause 26, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

[0202] Clause 28. The wearable biosensing system of clause 27, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a fifth strain gauge located circumferentially between the first pressure applicator and the fourth pressure applicator and a sixth strain gauge located circumferentially between the first pressure applicator and the second pressure applicator.

[0203] Clause 29. The wearable biosensing system of clause 28, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a seventh strain gauge radially spaced apart from the fifth strain gauge and an eighth strain gauge radially spaced apart from the sixth strain gauge.

[0204] Clause 30. A wearable biosensing system comprising a ring frame extending around an axis to define a passageway to receive a finger of a user therein, the ring frame including an inner wall adapted to contact a skin surface of the finger and an outer wall opposite the inner wall, the ring frame defining an interior spaceradially between the inner wall and the outer wall; a contact chassis including a pressure applicator configured to extend from the interior space of the ring frame through the inner wall toward the axis and into contact with the skin surface to apply a contact pressure to the skin surface and a bridge coupled to the ring frame and located in the interior space of the ring frame; and a biosensing unit mounted to the bridge of the contact chassis and located in the interior space of the ring frame, the biosensing unit including a first strain gauge and a second strain gauge circumferentially spaced apart from the first strain gauge about the axis, the first and second strain gauges configured to measure pressure data suitable for determining physiological signals of the user.

[0205] Clause 31 . The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge and the second strain gauge are spaced apart circumferentially about the ring frame to locate the pressure applicator therebetween.

[0206] Clause 32. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the bridge includes a first straight portion, a second straight portion circumferentially spaced apart from the first straight portion, and a curved portion extending between and interconnecting the first straight portion and the second straight portion.

[0207] Clause 33. The wearable biosensing system of clause 32, any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge is mounted to the first straight portion.

[0208] Clause 34. The wearable biosensing system of clause 33, any other suitable clause, or any other suitable combination of clauses, wherein the second strain gauge is mounted to the second straight portion.

[0209] Clause 35. The wearable biosensing system of clause 34, any other suitable clause, or any other suitable combination of clauses, wherein the pressure applicator is coupled to the curved portion.

[0210] Clause 36. The wearable biosensing system of clause 32, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a third strain gauge and a fourth strain gauge circumferentially spaced apart from the third strain gauge.

[0211] Clause 37. The wearable biosensing system of clause 36, any other suitable clause, or any other suitable combination of clauses, wherein the third strain gauge is mounted to the first straight portion and the fourth strain gauge is mounted to the second straight portion.

[0212] Clause 38. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a third strain gauge and a fourth strain gauge circumferentially spaced apart from the third strain gauge.

[0213] Clause 39. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises an inertial sensor configured to measure movement of the finger of the user.

[0214] Clause 40. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises a photoplethysmography (PPG) sensor configured to measure blood volume changes of the user.

[0215] Clause 41 . The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises an electrocardiography (ECG) sensor configured to measure electrical signal from a heart of the user.

[0216] Clause 42. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises a skin temperature sensor configured to measure skin temperature of the user.

[0217] Clause 43. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises a environmental temperature sensor configured to measure a temperature of an environment around the user.

[0218] Clause 44. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, further comprising a power unit configured to provide power to electronics of the wearable biosensing system, the power unit includes a rechargeable battery and an inductor charge coil configured to wirelessly recharge the rechargeable battery.

[0219] Clause 45. The wearable biosensing system of clause 44, any other suitable clause, or any other suitable combination of clauses, wherein the power unit is located in the interior space of the ring frame.

[0220] Clause 46. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the bridge is fixed to the ring frame.

[0221] Clause 47. The wearable biosensing system of clause 46, any other suitable clause, or any other suitable combination of clauses, wherein the bridge extends only partially circumferentially about the ring frame.

[0222] Clause 48. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the bridge extends between a first end and a second end thereof opposite the first end, and wherein the first end and the second end of the bridge are fixed to the ring frame.

[0223] Clause 49. The wearable biosensing system of clause 48, any other suitable clause, or any other suitable combination of clauses, wherein the pressure applicator is located circumferentially between the first end and the second end of the bridge about the ring frame.

[0224] Clause 50. The wearable biosensing system of clause 49, any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge is located circumferentially between the first end of the bridge and the pressure applicator and the second strain gauge is located circumferentially between the pressure applicator and the second end of the bridge.

[0225] Clause 51 . The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the bridge extends entirely circumferentially about the ring frame.

[0226] Clause 52. The wearable biosensing system of clause 51 , any other suitable clause, or any other suitable combination of clauses, wherein the pressure applicator is a first pressure applicator, and wherein the contact chassis further includes a second pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

[0227] Clause 53. The wearable biosensing system of clause 52, any other suitable clause, or any other suitable combination of clauses, wherein the second pressure applicator is circumferentially spaced apart from the first pressure applicator.

[0228] Clause 54. The wearable biosensing system of clause 52, any other suitable clause, or any other suitable combination of clauses, wherein the contact chassis further includes a third pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis and a fourth pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

[0229] Clause 55. The wearable biosensing system of clause 54, any other suitable clause, or any other suitable combination of clauses, wherein the first, second, third, and fourth pressure applicators are circumferentially spaced apart from one another about the axis.

[0230] Clause 56. The wearable biosensing system of clause 54, any other suitable clause, or any other suitable combination of clauses, wherein the first strain gauge is located circumferentially between the first pressure applicator and the fourth pressure applicator, and wherein the second strain gauge is located circumferentially between the first pressure applicator and the second pressure applicator.

[0231] Clause 57. The wearable biosensing system of clause 56, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

[0232] Clause 58. The wearable biosensing system of clause 57, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a fifth strain gauge located circumferentially between the first pressure applicator and the fourth pressure applicator and a sixth strain gauge located circumferentially between the first pressure applicator and the second pressure applicator.

[0233] Clause 59. The wearable biosensing system of clause 58, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further includes a seventh strain gauge radially spaced apart from the fifth strain gauge and an eighth strain gauge radially spaced apart from the sixth strain gauge.

[0234] Clause 60. The wearable biosensing system of clause 30, any other suitable clause, or any other suitable combination of clauses, wherein the contact chassis is mounted to the ring frame for movement relative to the ring frame.

[0235] Clause 61 . The wearable biosensing system of clause 60, any other suitable clause, or any other suitable combination of clauses, wherein the first and second strain gauges are mounted to the bridge for movement therewith relative to the ring frame.

[0236] Clause 62. The wearable biosensing system of clause 60, any other suitable clause, or any other suitable combination of clauses, wherein the contact chassis further includes a driver configured to move the contact chassis relative to the ring frame to change the contact pressure applied by the pressure applicator to the skin surface of the user.

[0237] Clause 63. The wearable biosensing system of clause 62, any other suitable clause, or any other suitable combination of clauses, wherein the driver includes a screw extending through the outer wall of the ring frame and into the contact chassis, and wherein the screw is configured to rotate to move the contact chassis relative to the ring frame.

[0238] Clause 64. The wearable biosensing system of clause 60, any other suitable clause, or any other suitable combination of clauses, wherein the contact chassis further comprises a shim configured to be mounted to the pressure applicator so that the ring frame accommodates various finger sizes.

[0239] Clause 65. A method comprising providing a ring frame, a contact chassis coupled to the ring frame, a first strain gauge coupled to the contact chassis, and a second strain gauge coupled to the contact chassis; moving the contact chassis relative to the ring frame so that the ring frame is sized to fit around a finger of a user; applying a contact pressure to a skin surface of the user by a pressure applicator of the contact chassis; and measuring pressure data by the first and second strain gauges suitable for determining physiological signals of the user.

[0240] Clause 66. The method of clause 65, any other suitable clause, or any other suitable combination of clauses, further comprising moving the contact chassis relative to the ring frame to change the contact pressure applied by the pressure applicator to the skin surface of the user.

[0241] Clause 67. The method of clause 65, any other suitable clause, or any other suitable combination of clauses, wherein the step of moving includes rotating a screw to cause movement of the contact chassis relative to the ring frame.

[0242] Clause 68. The method of clause 65, any other suitable clause, or any other suitable combination of clauses, further comprising locating at least a portion of the contact chassis in an interior space of the ring frame so that the pressure applicator protrudes outwardly from the interior space toward the finger

[0243] Clause 69. The method of clause 68, any other suitable clause, or any other suitable combination of clauses, further comprising locating the first and second strain gauges in the interior space of the ring frame.

[0244] Clause 70. The method of clause 65, any other suitable clause, or any other suitable combination of clauses, further comprising measuring blood volume changes of the user using a photoplethysmography (PPG) sensor.

[0245] Clause 71 . The method of clause 65, any other suitable clause, or any other suitable combination of clauses, further comprising, after the step of moving, coupling a shim to the pressure applicator and the ring frame.

[0246] Clause 72. The wearable biosensing system of clause 65, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises an electrocardiography (ECG) sensor configured to measure electrical signal from a heart of the user.

[0247] Clause 73. The wearable biosensing system of clause 65, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises a skin temperature sensor configured to measure skin temperature of the user.

[0248] Clause 74. The wearable biosensing system of clause 65, any other suitable clause, or any other suitable combination of clauses, wherein the biosensing unit further comprises an environmental temperature sensor configured to measure a temperature of an environment around the user.

[0249] While the disclosure has been illustrated and described in detail in the foregoing drawings and description, the same is to be considered as exemplary and not restrictive in character, it being understood that only illustrative embodiments thereof have been shown and described and that all changes and modifications that come within the spirit of the disclosure are desired to be protected.

Claims

WHAT IS CLAIMED IS:1 . A wearable biosensing system comprising a ring frame extending around an axis to define a passageway to receive a finger of a user therein, the ring frame including an inner wall adapted to contact a skin surface of the finger and an outer wall opposite the inner wall, the ring frame defining an interior space radially between the inner wall and the outer wall, a contact chassis including a pressure applicator configured to extend from the interior space of the ring frame through the inner wall toward the axis and into contact with the skin surface to apply a contact pressure to the skin surface and a bridge fixed to the ring frame and located in the interior space of the ring frame, and a biosensing unit mounted to the bridge of the contact chassis and located in the interior space of the ring frame, the biosensing unit including a first strain gauge and a second strain gauge circumferentially spaced apart from the first strain gauge about the axis, the first and second strain gauges configured to measure pressure data suitable for determining physiological signals of the user.

2. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge and the second strain gauge are spaced apart circumferentially about the ring frame to locate the pressure applicator therebetween.

3. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the bridge includes a first straight portion, a second straight portion circumferentially spaced apart from the first straight portion, and a curved portion extending between and interconnecting the first straight portion and the second straight portion.

4. The wearable biosensing system of claim 3, any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge is mounted to the first straight portion.

5. The wearable biosensing system of claim 4, any other suitable claim, or any other suitable combination of claims, wherein the second strain gauge is mounted to the second straight portion.

6. The wearable biosensing system of claim 5, any other suitable claim, or any other suitable combination of claims, wherein the pressure applicator is coupled to the curved portion.

7. The wearable biosensing system of claim 3, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

8. The wearable biosensing system of claim 7, any other suitable claim, or any other suitable combination of claims, wherein the third strain gauge is mounted to the first straight portion of the bridge and the fourth strain gauge is mounted to the second straight portion of the bridge.

9. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

10. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises an inertial sensor configured to measure movement of the finger of the user.1 1 . The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises a photoplethysmography (PPG) sensor configured to measure blood volume changes of the user.

12. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises an electrocardiography (ECG) sensor configured to measure electrical signal from a heart of the user.

13. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises a skin temperature sensor configured to measure skin temperature of the user.

14. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises an environmental temperature sensor configured to measure a temperature of an environment around the user.

15. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, further comprising a power unit configured to provide power to electronics of the wearable biosensing system, the power unit includes a rechargeable battery and an inductor charge coil configured to wirelessly recharge the rechargeable battery.

16. The wearable biosensing system of claim 15, any other suitable claim, or any other suitable combination of claims, wherein the power unit is located in the interior space of the ring frame.

17. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the bridge extends only partially circumferentially about the ring frame.

18. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the bridge extends between a first end and a second end thereof opposite the first end, and wherein the first end and the second end of the bridge are fixed to the ring frame.

19. The wearable biosensing system of claim 18, any other suitable claim, or any other suitable combination of claims, wherein the pressure applicator is located circumferentially between the first end and the second end of the bridge about the ring frame.

20. The wearable biosensing system of claim 19, any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge is located circumferentially between the first end of the bridge and the pressure applicator and the second strain gauge is located circumferentially between the pressure applicator and the second end of the bridge.21 . The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the bridge extends entirely circumferentially about the ring frame.

22. The wearable biosensing system of claim 1 , any other suitable claim, or any other suitable combination of claims, wherein the pressure applicator is a first pressure applicator, and wherein the contact chassis further includes a second pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

23. The wearable biosensing system of claim 22, any other suitable claim, or any other suitable combination of claims, wherein the second pressure applicator is circumferentially spaced apart from the first pressure applicator.

24. The wearable biosensing system of claim 22, any other suitable claim, or any other suitable combination of claims, wherein the contact chassis further includes a third pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis and a fourth pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

25. The wearable biosensing system of claim 24, any other suitable claim, or any other suitable combination of claims, wherein the first, second, third, and fourth pressure applicators are circumferentially spaced apart from one another about the axis.

26. The wearable biosensing system of claim 24, any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge is located circumferentially between the first pressure applicator and the fourth pressure applicator, and wherein the second strain gauge is located circumferentially between the first pressure applicator and the second pressure applicator.

27. The wearable biosensing system of claim 26, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

28. The wearable biosensing system of claim 27, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a fifth strain gauge located circumferentially between the first pressure applicator and the fourth pressure applicator and a sixth strain gauge located circumferentially between the first pressure applicator and the second pressure applicator.

29. The wearable biosensing system of claim 28, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a seventh strain gauge radially spaced apart from the fifth strain gauge and an eighth strain gauge radially spaced apart from the sixth strain gauge.

30. A wearable biosensing system comprisinga ring frame extending around an axis to define a passageway to receive a finger of a user therein, the ring frame including an inner wall adapted to contact a skin surface of the finger and an outer wall opposite the inner wall, the ring frame defining an interior space radially between the inner wall and the outer wall, a contact chassis including a pressure applicator configured to extend from the interior space of the ring frame through the inner wall toward the axis and into contact with the skin surface to apply a contact pressure to the skin surface and a bridge coupled to the ring frame and located in the interior space of the ring frame, and a biosensing unit mounted to the bridge of the contact chassis and located in the interior space of the ring frame, the biosensing unit including a first strain gauge and a second strain gauge circumferentially spaced apart from the first strain gauge about the axis, the first and second strain gauges configured to measure pressure data suitable for determining physiological signals of the user.31 . The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge and the second strain gauge are spaced apart circumferentially about the ring frame to locate the pressure applicator therebetween.

32. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the bridge includes a first straight portion, a second straight portion circumferentially spaced apart from the first straight portion, and a curved portion extending between and interconnecting the first straight portion and the second straight portion.

33. The wearable biosensing system of claim 32, any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge is mounted to the first straight portion.

34. The wearable biosensing system of claim 33, any other suitable claim, or any other suitable combination of claims, wherein the second strain gauge is mounted to the second straight portion.

35. The wearable biosensing system of claim 34, any other suitable claim, or any other suitable combination of claims, wherein the pressure applicator is coupled to the curved portion.

36. The wearable biosensing system of claim 32, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit furtherincludes a third strain gauge and a fourth strain gauge circumferentially spaced apart from the third strain gauge.

37. The wearable biosensing system of claim 36, any other suitable claim, or any other suitable combination of claims, wherein the third strain gauge is mounted to the first straight portion and the fourth strain gauge is mounted to the second straight portion.

38. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a third strain gauge and a fourth strain gauge circumferentially spaced apart from the third strain gauge.

39. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises an inertial sensor configured to measure movement of the finger of the user.

40. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises a photoplethysmography (PPG) sensor configured to measure blood volume changes of the user.41 . The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises an electrocardiography (ECG) sensor configured to measure electrical signal from a heart of the user.

42. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises a skin temperature sensor configured to measure skin temperature of the user.

43. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises a environmental temperature sensor configured to measure a temperature of an environment around the user.

44. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, further comprising a power unit configured to provide power to electronics of the wearable biosensing system, thepower unit includes a rechargeable battery and an inductor charge coil configured to wirelessly recharge the rechargeable battery.

45. The wearable biosensing system of claim 44, any other suitable claim, or any other suitable combination of claims, wherein the power unit is located in the interior space of the ring frame.

46. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the bridge is fixed to the ring frame.

47. The wearable biosensing system of claim 46, any other suitable claim, or any other suitable combination of claims, wherein the bridge extends only partially circumferentially about the ring frame.

48. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the bridge extends between a first end and a second end thereof opposite the first end, and wherein the first end and the second end of the bridge are fixed to the ring frame.

49. The wearable biosensing system of claim 48, any other suitable claim, or any other suitable combination of claims, wherein the pressure applicator is located circumferentially between the first end and the second end of the bridge about the ring frame.

50. The wearable biosensing system of claim 49, any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge is located circumferentially between the first end of the bridge and the pressure applicator and the second strain gauge is located circumferentially between the pressure applicator and the second end of the bridge.51 . The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the bridge extends entirely circumferentially about the ring frame.

52. The wearable biosensing system of claim 51 , any other suitable claim, or any other suitable combination of claims, wherein the pressure applicator is a first pressure applicator, and wherein the contact chassis further includes a second pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

53. The wearable biosensing system of claim 52, any other suitable claim, or any other suitable combination of claims, wherein the second pressure applicator is circumferentially spaced apart from the first pressure applicator.

54. The wearable biosensing system of claim 52, any other suitable claim, or any other suitable combination of claims, wherein the contact chassis further includes a third pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis and a fourth pressure applicator that extends from the interior space of the ring frame through the inner wall toward the axis.

55. The wearable biosensing system of claim 54, any other suitable claim, or any other suitable combination of claims, wherein the first, second, third, and fourth pressure applicators are circumferentially spaced apart from one another about the axis.

56. The wearable biosensing system of claim 54, any other suitable claim, or any other suitable combination of claims, wherein the first strain gauge is located circumferentially between the first pressure applicator and the fourth pressure applicator, and wherein the second strain gauge is located circumferentially between the first pressure applicator and the second pressure applicator.

57. The wearable biosensing system of claim 56, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a third strain gauge radially spaced apart from the first strain gauge and a fourth strain gauge radially spaced apart from the second strain gauge.

58. The wearable biosensing system of claim 57, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a fifth strain gauge located circumferentially between the first pressure applicator and the fourth pressure applicator and a sixth strain gauge located circumferentially between the first pressure applicator and the second pressure applicator.

59. The wearable biosensing system of claim 58, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further includes a seventh strain gauge radially spaced apart from the fifth strain gauge and an eighth strain gauge radially spaced apart from the sixth strain gauge.

60. The wearable biosensing system of claim 30, any other suitable claim, or any other suitable combination of claims, wherein the contact chassis is mounted to the ring frame for movement relative to the ring frame.61 . The wearable biosensing system of claim 60, any other suitable claim, or any other suitable combination of claims, wherein the first and second strain gauges are mounted to the bridge for movement therewith relative to the ring frame.

62. The wearable biosensing system of claim 60, any other suitable claim, or any other suitable combination of claims, wherein the contact chassis further includes a driver configured to move the contact chassis relative to the ring frame to change the contact pressure applied by the pressure applicator to the skin surface of the user.

63. The wearable biosensing system of claim 62, any other suitable claim, or any other suitable combination of claims, wherein the driver includes a screw extending through the outer wall of the ring frame and into the contact chassis, and wherein the screw is configured to rotate to move the contact chassis relative to the ring frame.

64. The wearable biosensing system of claim 60, any other suitable claim, or any other suitable combination of claims, wherein the contact chassis further comprises a shim configured to be mounted to the pressure applicator so that the ring frame accommodates various finger sizes.

65. A method comprising providing a ring frame, a contact chassis coupled to the ring frame, a first strain gauge coupled to the contact chassis, and a second strain gauge coupled to the contact chassis, moving the contact chassis relative to the ring frame so that the ring frame is sized to fit around a finger of a user, applying a contact pressure to a skin surface of the user by a pressure applicator of the contact chassis, and measuring pressure data by the first and second strain gauges suitable for determining physiological signals of the user.

66. The method of claim 65, any other suitable claim, or any other suitable combination of claims, further comprising moving the contact chassis relativeto the ring frame to change the contact pressure applied by the pressure applicator to the skin surface of the user.

67. The method of claim 65, any other suitable claim, or any other suitable combination of claims, wherein the step of moving includes rotating a screw to cause movement of the contact chassis relative to the ring frame.

68. The method of claim 65, any other suitable claim, or any other suitable combination of claims, further comprising locating at least a portion of the contact chassis in an interior space of the ring frame so that the pressure applicator protrudes outwardly from the interior space toward the finger69. The method of claim 68, any other suitable claim, or any other suitable combination of claims, further comprising locating the first and second strain gauges in the interior space of the ring frame.

70. The method of claim 65, any other suitable claim, or any other suitable combination of claims, further comprising measuring blood volume changes of the user using a photoplethysmography (PPG) sensor.71 . The method of claim 65, any other suitable claim, or any other suitable combination of claims, further comprising, after the step of moving, coupling a shim to the pressure applicator and the ring frame.

72. The wearable biosensing system of claim 65, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises an electrocardiography (ECG) sensor configured to measure electrical signal from a heart of the user.

73. The wearable biosensing system of claim 65, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises a skin temperature sensor configured to measure skin temperature of the user.

74. The wearable biosensing system of claim 65, any other suitable claim, or any other suitable combination of claims, wherein the biosensing unit further comprises an environmental temperature sensor configured to measure a temperature of an environment around the user.

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