EP4709913A2

EP4709913A2 - Biosymbiotic systems for chronic long-range monitoring of biosignals in limited resource settings

Info

Publication number: EP4709913A2
Application number: EP24807848.7A
Authority: EP
Inventors: Philipp Gutruf; Tucker STUART
Original assignee: University of Arizona
Current assignee: University of Arizona
Priority date: 2023-05-12
Filing date: 2024-05-10
Publication date: 2026-03-18
Also published as: AU2024273563A1; AU2024273563C1; WO2024238390A3; WO2024238390A2

Abstract

The present disclosure provides a wearable article including a 3D printed base, 3D printed antenna ground plane structure and a 3D printed a dipole antenna structure, wherein the base, ground plane structure and dipole antenna structure comprises a 3D printed mesh which is formed of a stretchable elastomeric polymer material. The wearable article also includes signal transmission and power harvesting circuitry comprising duplexing circuit to transmit and receive data and to receive wireless power from a power transmission unit.

Description

BIOSYMBIOTIC SYSTEMS FOR CHRONIC LONG-RANGE MONITORING OF BIOSIGNALS IN LIMITED RESOURCE SETTINGS

Cross-Reference to Related Applications

[0001] The present application claims the benefit of U.S. Provisional Application Serial No. 63/466,213 filed 12-May-2023, which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to biosymbiotic systems for chronic long-range monitoring of biosignals.

BACKGROUND INFORMATION

[0003] The need for accurate, fast, and robust remote patient monitoring is an important aspect of realizing digital medicine concepts. This has been further accentuated by the COVID-19 pandemic, which showed unprecedented strain on the healthcare system and a renewed call for remote monitoring capabilities. The proliferation of internet of things (loT) networks has played a large role in realizing these concepts by providing an infrastructure for interconnected devices. These device generally span both wearable and implantable sensors that are able to extract high- fidelity information from the underlying physiology and communicate that information wirelessly for aggregation and investigation. Devices for these applications commonly implement near-field communication, Bluetooth Low Energy, or WiFi as communication modalities. While these modalities are robust and well developed, they are limited in use due to the inherit infrastructure requirements, such as adequate cell coverage, connectivity to the internet for application program interfacing, and main-line power sources for extended operation of battery-powered loT devices. These infrastructure requirements drive cost and restrict device operation in low resource or remote settings where suitable infrastructure has not been developed. While some solutions have aimed to address this through the use of satellite communication, the powering, hardware, and cost requirements for implementation inhibit broad dissemination in limited resource environments. To address this, the use of low-power wide area network (LPWAN) protocols such as ultra-narrow band (UNB), LoRa, and SigFox have been realized for long-range, remote loT applications. [0004] Despite the development of these capabilities, there has been limited work conducted on realizing wearable devices that host this functionality. This is in part due to the high power requirements of long-range communication and the need for large, bulky battery supplies and antennas that impose a significant burden on users and limit sensing modalities and fidelity. Realization of a device architecture with this functionality serves as an important milestone in realizing remote patient monitoring in remote and low-resource settings, where access to healthcare remains limited. Recent advances in wearable biosymbiotic device architecture paired with proliferation of complementary electronics to harness long-range data communication pose a promising avenue for realization of this technology. Implementation of such a device could serve as a viable solution for remote patient monitoring in rural or limited resource setting and enable healthcare providers or clinicians to accurately predict, diagnose, and treat various disease paradigms, improving patient access to care and reducing the financial burden of remote healthcare.

BRIEF DESCRIPTION OF THE DRAWINGS

[0005] Features and advantages of various embodiments of the claimed subject matter will become apparent as the following Detailed Description proceeds, and upon reference to the Drawings, wherein like numerals designate like parts, and in which:

[0006] FIG. 1 illustrates biosymbiotic devices for long-range transmission of biosignals in accordance with several embodiments of the present disclosure; where FIG. 1 A is an illustration of device operation in remote settings with wireless recharging capabilities; FIG. IB is a schematic overview of device operation showing both data transmission and power harvesting capabilities; FIG. 1C is an image showing biosymbiotic device attached to the wrist for heart rate and skin temperature recording with functional units labeled;

[0007] FIG. 2 illustrates signal transmission and power harvesting characterization in accordance with several embodiments of the present disclosure; where FIG. 2A is a circuit schematic showing PIN diode duplexing circuit with full wave rectification; FIG. 2B is a plot of S¹¹ measurements of a serpentine dipole antenna with flexible ground plane and the effect of rectification and PIN diode circuits; FIG. 2C is a graph showing power voltage curve for device located at 30 cm from the transmitter under decreasing loads; FIG. 2D is a graph of data transmission percentage and power output as a function of distance from the transmitter with a 1 k£2 system load; FIG. 2E is a plot of recorded antenna performance as a function of angular rotation along the principal axes; FIG. 2F is a 3D representation of signal power measured at the receiver with variations of spreading factor and transmission power; FIG. 2G is a plot of received signal strength indicator as a function of distance from the receiver for on-body serpentine antenna and commercial monopole; and FIG. 2H is a plot of specific adsorption rate (SAR) values at 915 MHz with varying transmission powers with an inset showing FED analysis of SAR on a human phantom model;

[0008] FIG. 3 illustrates electrical and sensor characteristics in accordance with several embodiments of the present disclosure; where FIG. 3A is a photographic image of biosymbiotic device placed on the distal portion of the forearm with sensing modalities highlighted; FIG. 3B is a simplified electrical schematic showing functional components of the biosymbiotic device; FIG. 3C is a graph of power consumption profile of the device showing key events such as deep sleep, signal aggregation and processing, and LoRa transmission; FIG. 3D is a graph showing effect of recording and transmission duty cycle on mean current consumption; FIG. 3E is a plot of raw photoplethysmography (PPG) and corresponding acceleration data collected during a high-motion event; FIG. 3F is a plot showing the computation time to calculate average heart rate as a function of the number of samples collected and the corresponding percentage error when compared to the gold standard system; and FIG. 3G is a plot of heart rate data extracted from the biosymbiotic device during rest and exercise (red);

[0009] FIG. 4 illustrates a long-range and long-term system demonstration according to one embodimenbt of the present disclosure; where FIG. 4A is a photographic image of biosymbiotic device placed on the distal portion of the forearm during long-range demonstration; FIG. 4B is a digital map showing relative location of transmission and receiving devices; FIG. 4C is a topographical map showing hiking route used during long-range experiment; FIG. 4D is an image showing a hiking trail used during long-range data collection experiment; FIG. 4E is a plot of skin temperature and recorded heart rate during long-range experiment; FIG. 4 F is a plot of skin temperature and heart rate recorded during 1 week of continuous data collection; FIG. 4G is an image of a user wearing long-range device during office work with wireless power transfer; FIG. 4H is an image of a user wearing long-range device during moderate activity; and FIG. 41 is an image of a user wearing device during daily activities; [0010] FIG. 5 illustrates various views of device dimensions and encapsulation according to an embodiment;

[0011] FIGS. 6A-6D illustrate various plots comparing the PIN diode circuit and a full wave rectifier according to an embodiments;

[0012] FIGS. 7A-7D illustrate various plots of LoRa communication parameters on transmission performance according to an embodiments;

[0013] FIGS. 8A-8B illustrate plots of the effects of cooling rate and bandwidth on power consumption according to embodiments;

[0014] FIG. 9 illustrates various views of the antenna design according to an embodiment;

[0015] FIG. 10 illustrates plots of specific absorption rates (SAR) models; where FIG. 10A is a plot of an FEA simulation of SAR during device receiving power; and FIG. 10B is a plot of FEA simulation of SAR during device transmission;

[0016] FIGS. 11A-11B illustrate photoplethysmography node design and characterization according to an embodiments; and

[0017] FIG. 12 illustrates log-range data collection according to various embodiments; where FIG. 12A is an image showing beginning of hiking trail used during long-range data collection; FIG. 12B illustrates heart rate and skin temperature data collected during first resting period; FIG. 12C is an image collected during hiking period of long-range data collection; FIG. 12D is a plot of heart rate and skin temperature data collected during activity; FIG. 12E is an image showing location of receiver module during the second resting period of long-range data collection; and FIG. 12F is a plot of heart rate and skin temperature data collected during second resting period.

[0018] Although the following Detailed Description will proceed with reference being made to illustrative embodiments, many alternatives, modifications and variations thereof will be apparent to those skilled in the art. DETAILED DESCRIPTION

[0019] The present disclosure provides biosymbiotic systems that utilizes advances in wearable device technology to enable long-range collection of biosignals without the need for substantial infrastructure support.

[0020] Biosmbiotic Devices for Remote Monitoring of Biosignals

[0021] FIG. 1A provides an overview of the operation of remote monitoring system of the present disclosure, which features remote, long-range data transmission (e.g., 15 miles) from the user and passive, wireless recharging. To achieve this, the present disclosure provides design and optimization of the device mechanics and electromagnetics. FIG. IB illustrates a circuit diagram of a remote monitoring system 100 according to embodiments of the present disclosure. The remote monitoring system 100 generally includes a wearable portion 120 communicatively coupled to a remote portion 140. The wearable portion 120, and as described in greater detail herein, includes power circuitry 122 that includes a reachgargeble battery 124 and battery management circuitry 126 to control charge and discharge of the battery 124. The wearable portion also includes antenna circuitry 128 generally configured to exchange commands and data with the remote portion 140 and to receive power (for the battery 124) from the remote portion 140. The antenna circuitry 128 includes antenna control circuitry 130 and multiplexing circuitry 132. The wearable portion 120 also includes sensor and communications circuitry 134 generally configured to sense one or more biosignals, and communicate the sensed biosignals to the remote portion 140. In example embodiments described herein, the sensor and communications circuitry 134 includes heart rate sensor circuitry 136A and temperature sensor circuitry 136B generally configured to sense heart rate and skin temperature of a wearer of the wearable portion 102. The sensor and communications circuitry 134 also includes wireless communications circuitry 138 (e.g., LoRa circuitry) to exchange commands and data with the remote portion 140.

[0022] The remote portion 140 includes power transmitter circuitry 142 generally configured to wirelessly transmit power (power harvesting) to the wearable portion 120 to charge the battery 124 via battery management circuitry 126. The remote portion 140 and includes data reception and storage circuitry 144, which may be embodied as a general purpose computer and/or applicationspecific integrated circuit, to receive sensed biosignals from the wearable portion 120. The data reception and storage circuitry 144 may be configured for storage and manipulation of data received from the wearable portion, as described herein.

[0023] In example embodiments, the system 100 utilizes a single 915 MHz antenna that allows both energy harvesting from a commercially available power casting unit and long-range data transmission using, for example, low power, wide area network (LPWAN) communications protocols such as LoRa, LoRaWAN, etc., long-range communication protocols. LoRa is a patented communication protocol that is a derivative of chirp spread spectrum with integrated forward error correction and utilizes a wide band transmission to handle potential frequency offsets and noise. A LoRa receiving unit can decode transmissions with power well below the noise floor, enable long-distance and robust communication schemes. Due to its operation inside the 915 MHz ISM band in the United States, this makes this communication scheme an interesting alternative to traditional modalities that host limited communication distances and require extensive infrastructure. Additionally, communication using LoRa provides the capability to extend communication distances to hundreds of miles with the utilization of multiple gateways and deployment of LoRa wireless area networks (LoRaWAN).

[0024] Control between receiving (Rx) and transmission (Tx) is managed by an integrated, LoRa-enabled microcontroller (138) and a PIN diode duplexing circuit (132), which allows for alternation between the two operational modes without the need for an additional antenna. Received alternating current (AC, from power transmitter 142) is rectified to direct current (DC) using a full bridge rectifier and processed by a battery-management circuit (126) for controlled lithium-polymer (LiPo) battery (124) recharging and system powering. The wearable portion 120 includes heart rate (HR, 136A) and skin thermography (136B) sensing capabilities that allow for assessment of user health status at regular intervals. An example wearable schematic of the wearable portion 120 is illustrated in FIG. 5.

[0025] An example wearable portion is shown in FIG. 1C, and includes 3D printed mesh using fusion deposition modeling (FDM) printing and a commercially available thermoplastic polyurethane (TPU) filament. This enables control over discreate device mechanics and geometries, such as the implemented flexible ground plane 135, while allowing for embedding of functional components for device operation. A 3D printed dipole antenna structure 130 is illustrated being disposed over the ground plane 135. Active electronic components are placed on flexible, circular islands of no more than 6 mm in diameter. These islands are connected via stretchable serpentine interconnects 151 , enabling soft mechanics and a low average device density to facilitate free perspiration and epidermal turnover. The resulting enables continuous recording of biosignals without interface disruption and controlled placement of sensors to optimize clinical relevance. This device features the ability to process and transmit biosignals information beyond limitations of typical a wearable device with capabilities to passively recharge, allowing for extended use in limited resource settings.

[0026] Signal Transmission and Power Harvesting

[0027] FIG. 2A illustrates example signal transmission and power harvesting circuitry 200 according to one embodiment of the present disclosure. To realize Rx and Tx capabilities using a single on-body antenna, a duplexing circuit 202 is deployed to isolate the respective Rx and Tx circuits. To achieve this, PIN diodes 204 and 206 are utilized. When an external voltage is applied to the “transmission enable” line via a general-purpose input/output (GPIO) pin, the PIN diode’s internal resistance changes, allowing power from the transmission line to pass through the diode to the on-body antenna, as illustrated in FIG. 2A. Alternatively, when the “transmission enable line” is pulled to ground at the GPIO pin, both PIN diodes exhibit high resistance, driving power through the full bridge rectifier and into the battery management system. This enables single antenna duplexing for use in both wireless power transfer and long- range data communication.

[0028] These circuits have minimal effect on antenna performance. FIG. 2B shows reflection measurements of the serpentine antenna system 210 disposed on the skin of a wearer with varying rectification schemes. An initial resonance of 908 MHz with a return loss of -10.42 dB is observed with the antenna and no rectification. The addition of the rectification circuits shifts the resonance to 916 MHz with return losses of -11.04 and -11.85 dB for a full bridge rectifier and PIN rectification circuit, respectively. The corresponding rectenna performance is shown in FIG. 2C, where output voltage and power are recorded at 30 cm from the transmitter. The maximum power point (MPP) is set at a 554 Q load with peak power output of 16.57 mW. The rectenna shows adequate power harvesting capabilities (average 4.82 mW) over the range of 5-10 k , which is more appropriate given the low duty cycle of the device. Spatial performance of the device in relationship to the power casting unit is shown in FIG. 2D. Here, we observe 30.03 mW harvested at 15 cm from the power caster with 9.47 mW and 2.56 mW observed at 50 cm and 100 cm, respectively. Additionally, the PIN diode duplexing circuit enables continuous data collection throughout the operational space, which was not possible with other methods (as illustred generally in FIGS. 6, described below. FIG. 2E shows rotational performance of the on-body rectenna along its principal axes. The rectenna shows robust operation about the yaw axis; however, sensitivity to angular offset about the roll and pitch axes due to the polarization of the antenna and effect of the body is recorded as expected for a dipole antenna.

[0029] LoRa enabled devices can be configured using several different parameters which affect the communication protocol and subsequently transmission distance and power consumption. Modulation of these features is important when designing a system to balance performance and power requirements. These parameters include transmission power, spreading factor, bandwidth, and coding rate, with transmission power and spreading factor having the most significant impact on transmission distance (see FIG. 7) and power consumption (see FIG. 8). This is further demonstrated in FIG. 2F, which shows a 3D map of the relative power received at the receiving unit as a function of changes in spreading factor and transmission power. Here the transmission power can be adjusted between 10 and 20 dbm, with higher powers enabling longer transmission distances at the cost of higher energy requirements. The spreading factor is the ratio between symbol and chip rates, with higher spreading factors resulting in increases to signal to noise ratio, and subsequently sensitivity and range. Higher spreading factors also result in higher power consumption as the transmission duration also increases. Due to the low operational duty cycle of the device and to maximize transmission distance, a spreading factor of 12 and a transmission power of 20 dBm was selected.

[0030] Transmission performance is demonstrated in FIG. 2G, which shows a comparison between the on-body serpentine antenna and a commercially available monopole antenna Here, we see similar performance designated by the received signal strength indicator (RSSI) value recorded at the receiver. As the distance increases, the two antennas show similar performance (within 6% variation RSSI), with the on-body antenna outperforming the commercially available monopole by 2.8% at 15 miles. Due to the high transmission power for long-range data transmission, specific adsorption rate (SAR) is a concern. With the addition of a flexible ground plane, these effects can be mitigated below federal communications commission (FCC) requirements. In fact, for transmission powers up to 25 dBm, we observe a SAR less than 0.295 W/kg of adsorption during transmission events, well below the U.S. guideline for an exposure of less than or equal to 1.6 W/kg (see FIG. 2H). Previous demonstrations have shown that adsorption during wireless power transfer is also well below regulation, and has been further demonstrated with this platform (see FIG. 10).

[0031] System Integration and Characterization

[0032] Utilizing 3D-enabled antennas and complimentary LoRa communication protocols enables a device that is capable of continuous, high-fidelity recording of biosignals and LoRa communication. To demonstrate this, a biosymbiotic device with LoRa-enabled microcontroller, multimodal sensors, and battery supplied is realized (see FIG. 3A). The device is attached to the distal portion of the forearm, allowing for placement of the optical sensor near the volar aspect of the wrist for physiologically relevant recording. FIG. 3B shows an electrical schematic of the functional components of the system, which features an analog sub-millikelvin resolution temperature sensor based on a Wheatstone bridge design. The sensor is encapsulated based as detailed perviously, and features low thermal and mechanical mass, allowing for high sensitivity measurements. This device also hosts digital communication to an integrated optical sensor for PPG recording. The sensor utilizes a cut out in the TPU mesh and laminated elastomeric material doped with a black dye (5 %wt), to enable conformal contact to the body to shield the sensor from optical noise of the environment (see FIG. 9) substantially reducing motion artefacts and enabling data collection during high physical activity.

[0033] The transmission parameters used for data communication greatly influence the power consumption of the device. To mitigate these effects, low duty cycle (<20%) operation is used. This is relevant for many applications that only require occasional data acquisition and not high temporal fidelity measurements. An example of one collection and transmission event is shown in FIG. 3C. The device remains in deep sleep with an average current consumption of 10.5 pA when not in use (highlighted in green). Upon waking up, the microcontroller begins collecting data from peripheral sensors (add frequency here) and packages information to be sent via LoRa (highlighted in red). Once computation is complete, data is sent via a high-power transmission event which averages 148.6 mA for 800 ms. By modulating the frequency of data collection and storage on the device and sending events, we can provide physiologically relevant temporal resolution while maintaining reasonable average power consumption as presented in FIG. 3D. Here we can see that with low duty cycles, which we would expect as adequate for limited resources settings, an average current consumption of less than 2 mA can be achieved. [0034] A new sensing modality for the biosymbiotic platform is demonstrated by optical recording of physiology using a PPG IC for extraction of user heart rate near the volar aspect of the wrist. For this modality, variation in infrared (IR) adsorption induced by volumetric variation in underlying vasculature can be used to monitor heart rate. FIG. 3E shows raw IR signal collected during subject rest. Due to the transmission limitations of LoRa, a computational method is deployed on the LoRa-enabled microcontroller to perform localized peak detection and average heartrate calculation. This enables reduction of total size and frequencies of the transmitted packages, increasing transmission distance at the expense of on-board computational time. The code utilizes a localized peak detection and collects a defined number of samples before using the different in time between peaks to estimate heart rate. The tradeoff between computational time and accuracy is depicted in FIG. 3F. Here we see that the number of samples collected for computation follows a linear trend with an increase of average on-board computational time of nearly 1.42 samples/second; however, the percentage error when compared to a gold- standard, finger-mounted PPG device shows a logarithmic decrease. In fact, as the numbers of samples increase, the percentage error shows minimal change after 6 samples. To maintain a balance between computational time and percentage error, a 5-sample computational scheme is selected, which yields an average computational time of 9.2 seconds and percent error of 4.2% (see FIG. 11). FIG. 3G shows the sensitivity of this platform when deployed onto the wrist. In this experiment, the subject begins in a seated position (shaded white) and then performs a walk at 3 miles/hour at a 3-degree incline for 10 minutes (shaded red). Although we observe a distribution of heart rate values (standard deviation = 4 bpm), the average recording clearly shows an increase in heart rate during mild exercise, which begins to return to baseline after rest. Results from these experiments verify the sensitivity of the device to monitor changes in heart rate during moderate exercise and maintain an adequate sensing interface throughout motion. Additionally, the algorithm used to calculate heart rate maintains good average compliance throughout use.

[0035] Long-range and Long-term System Demonstration.

[0036] To demonstrate the capabilities of this platform, a biosymbiotic device is fabricated for placement of the distal portion of the forearm with capabilities described previously (see FIG. 4A). This system is deployed onto a user in a remote location of the desert with a receiving unit placed 15 miles away (see FIG. 4B). The participant is then asked to hike a predetermined route indicated in FIG. 4C, which consisted of moderate mountainous terrain with elevation changes (± 98 m) (see FIG. 4D). The device is programmed for transmission at approximately 5 mHz, although the actual transmission time is dependent on variations of on-board computational time for heart rate calculation. Data collected during this experiment is presented in FIG. 4E. Resting heart rate begins at an average of 72 bpm, which increases during activity to a peak of 104 bpm before returning to 89 bpm during the second resting period. Similarly, an increase in local skin temperature is observed from 34.3 °C to 36.7 °C, which follows a similar delayed increase when compared to the heart rate data. Despite the low transmission frequency, because of the onboard computation the device was able to detect and transmit relative changes in temperature and heart rate induced by moderate exercise to a receiver located 15 miles away (see FIG. 12).

[0037] Although the core intention of the device is for operation in rural areas, adoption of this system in more developed and urban areas is also possible. Implementation in this manner holds benefit over conventional device platforms in scenarios where continuous monitoring is required; however, conventional wired recharging and data aggregation infrastructure is not feasible. To demonstrate long-term operational capabilities in urban environments, a 7-day experiment is performed. Raw data heart rate, thermography, and battery voltage data is displayed in FIG. 4F. During this experiment, the device operates continuously at 5 mHz and is passively recharged when the user is near a power caster placed in locations of high occupancy, such as the bedside table and work desk (see FIG. 4G). Battery voltage is monitored at regular 8-hour intervals, with regions shaded in green indicating proximity to a power casting unit. We see continuous data collection of heart rate and skin temperature over time, with compliance between measured increases in heart rate and noted periods of physical activity (shaded in red). Periods of moderate activity, such as walking can also be observed in less pronounced increases in heart rate (see FIG. 4H). The device exhibits robust operation in several different scenarios in urban settings, enabling continuous high-fidelity biosignals collection and communication regardless of activity (see FIG. 41).

[0038] Despite dissemination of wearable technology for broad use in digital medicine applications, wide proliferation of technology remains a significant barrier to realizing continuous healthcare monitoring in rural and limited resource settings. Key hurdles to implementing equitable and effective remote and digital healthcare in these communities lie in the lack of connectivity infrastructure such as cell reception to host the most common loT communication modalities. To address these challenges, the present disclosure provides a biosymbiotic platform that has demonstrated capabilities to record high fidelity biosignals and transmit data over a 15- mile distance with uninterrupted operation over a week, well beyond limitations imposed by epidermal turnover.

[0039] Demonstrations of this device include a 2400x and 533x increase in communication distance when compared to common modalities such as Bluetooth low energy and Wifi, respectively. While this demonstration focuses on a single LoRa transmitter and receiver, future work seeks to further improve and extend communication distances with the implementation of LoRaWAN gateways that can serve hundreds of square miles of coverage with only a hand full of connection points. Long-term and long-range recording capabilities demonstrated with this platform serve as an important milestone in delivering solutions to currently underserved patient populations. Implementation of this device class has broad applicability in several scenarios including remote monitoring in rural and limited resource communities, high-fidelity recording in war zones, and even monitoring health in developed denes urban environments.

[0040] Circuit Design and Fabrication

[0041] Functional units for the device were patterned onto flexible printed circuit boards (fPCB). These fPCBs were designed in AutoCAD (Autodesk) and panelized by an external manufacturer (PCBway). Modular fPCB components were defined using a 355 nm laser ablation system (Protolaser U4, LPKF). fPCBs were subsequently washed with isopropyl alcohol (IP A) and deionized (DI) water to remove carbon buildup from the ablation process. Commercially available components were placed by hand and reflowed with a hot air gun set at 350°C and low- temperature solder paste (TS391LT, Chip Quik). The serpentine-based dipole antenna was tuned to 915 MHz on the skin using a spectrum analyzer (SSA 3032X, Siglent) and a reflection bridge (RB3X20, Siglent). The serpentine shape was placed on the proximal region of the forearm, and each pole of the dipole was cut consecutively until sl l plots showed resonance at 915 MHz. A duplexing circuit was designed using a full bridge rectifier with 0201 components including low- forward voltage Schottky diodes (SMS7630-061, Sky words), PIN diodes (BAR63-02L, Infineon) and smoothing capacitors. Rectified power was sent to a power management IC (ADP5090ACPZ- 1-R7, Analog Devices) which controlled recharging of a small lithium polymer battery (150 mAh) and managed maximum power point tracking (MPPT) functionality. A 3.3V low-dropout (LDO) regulator was used to stabilize voltage to peripheral sensors and the LoRa microcontroller (ASR6501, ASR Microelectronics). The LoRa microcontroller was programmed using Arduino IDE before being placed onto the fPCB. The on-body thermography used a 100 Q negative temperature coefficient thermistor deployed in a wheat stone bridge configuration and a differential amplifier to produce analog temperature readings that were then digitized by the onboard analog to digital converter (ADC). Optical recordings were carried out using a commercially available integrated circuit (IC) (MAX30102, Maxim Integrated).

[0042] Mesh Design and Fabrication

[0043] 2D mesh drawings designed utilizing the digital design process described in Stuart et al. (T. Stuart, et al., Context-aware electromagnetic design for continuously wearable biosymbiotic devices. Biosens. Bioelectron. (2023) https:Zdoi.org/10.1016/j.bios.2023.115218, and T. Stuart, et al., Biosymbiotic, personalized, and digitally manufactured wireless devices for indefinite collection of high-fidelity biosignals. Sci. Adv. 7, eabj3269 (2021)) and integrated into the electronics design in AutoCAD. Drawings were exported from AutoCAD in drawing exchange format and imported into a 3D computer-aided design software (Fusion360, Autodesk) for 3D design. Stereolithography (STL) files were generated from the 3D model and imported into 3D slicing software (PrusaSlicer, Prusa3D) to generate machine code for the 3D printing. A fusion deposition modeling printer (CR-lOs, Creality) was outfitted with a custom x-axis carriage that housed a direct drive extruder (Flexion, Diabase Engineering), hot end, and automatic bed leveling unit (BLTouch, Antclabs). A commercially available thermos plastic polyurethane (TPU) filament (NinjaFlex, NinjaTek) was printed at 45 mm/s and 225°C with a bed temperature of 45°C. Using the pause at height command, the printer was paused to allow for insertion of electrical components and fPCBs by hand into the elastomeric channels using the channel structure to guide electronics placement. After printing, electronics were encapsulated and segmented sections of the mesh structure were joined by melting TPU material together at junctions to form the completed linear structures.

[0044] Antenna Characterization

[0045] Reflection measurements were carried out using a spectrum analyzer (SSA 3032X, Siglent) and a reflection bridge (RB3X20, Siglent). The serpentine design was chosen to have a central angle of 240° with a radius of 3 mm. The serpentine antenna was embedded into a structure that was raised 2.55 mm from the flexible ground plane with SMA connectors soldered at the intersection of the poles to the rectification circuit. The antenna was placed onto the body at the proximal region of the forearm during reflection measurements and the ends of the serpentine were cut equally on both sides until resonance was reached at the target 915 MHz frequency. The resulting dipole length was recorded to be 83 mm total. Specific adsorption rate characterization was carried out using finite element modeling (Ansys HFSS, Ansys). To measure free space antenna wireless power transfer performance, the rectenna was attached to a 3D-printed Polylactic Acid (PLA) apparatus that allowed for positional and angular manipulation of antenna. The power casting unit was placed on a wooden table and short wires were used to attach the antenna to a multimeter (DT132A, AstroAI). Various resistors were used to mimic system loads while the voltage output was measured at varying distances from the power casting unit (TX91501B, Powercast), as well as at different rotational positions along the principal axes of the antenna. For on-body measurements, the antenna was attached to the proximal region of the forearm with similar recording infrastructure.

[0046] Electrical Characterization

[0047] Current consumption of the device was recorded using a laboratory benchtop power supply (5 V) and a custom current meter with an internal shunt of 1 Q connected in series with the 3.3 V supply line to the device. Modulation of sampling frequency and sensors was programmed in Arduino IDE. The data was acquired in real time using an oscilloscope (SDS 1202X-E, Siglent) and average power consumption was calculated using MATLAB.

[0048] Heart Rate Testing and Validation

[0049] A high-sensitivity pulse oximeter IC (MAX30102, Maxim Integrated) was deployed into a biosymbiotic mesh structure attached to the distal portion of the forearm. The IC was connected to the LoRa-based microcontroller via I²C serial communication protocol using 10 k£l pull up resisitors. The IC was placed into a TPU cut out, and an elastomeric material (184 Silicone Elastomer Kit, Sylgard) doped with a black dye (5 %wt) was laminated onto the TPU to provide a robust optical interface to the underlying tissue. The optical intensity of the LEDs was tuned onto the wrist to provide accurate and stable PPG recordings. To test the sample size needed for heart rate estimation, the device was worn on the wrist and a finger oximeter (FL400, FaceLake) was used to collect simultaneous heart rate measurements. Data collected from this experiment was compared to values collected using carotid pulse and heart rate values generated from the finger oximeter. Calculation times were also noted. To test robustness against motion and sensitivity, a device was deployed onto the distal portion of the wrist of the user. The user was then asked to perform a series of 10-minute walks on a treadmill with an incline of 3 degrees. Data was collected continuously and plotted.

[0050] Temperature Sensor Development and Characterization

[0051] A 100 kQ NTC thermistor (NTCG064EF104FTBX, TDK Corporation) was placed on the back side of a fPCB (3 mm in diameter) and balanced using a wheat stone bridge configuration with 0201 components. The NTC was balanced with a 69 kQ resistor to provide the correct reference voltage of 0.116 V. Voltages from the bridge were fed into a differential amplifier (ADA4505-1, Analog Devices) with gain set to 82.64X using 10 MQ and 121 kQ resistors. Characterization of the NTC thermistor was carried out using a proportional-integral-derivative (P1D) controlled hot plate where the NTC and commercially available digital thermocouple (HT- 9815, Hti-Xintai) were secured to the system. Temperature was increased in 0.5 °C increments and left for 2 minutes for the temperature to stabilize. The ADC readout was recorded, as well as the commercial thermistor readings and ADC values were converted to voltage. Results were collected and a standardized curve was developed.

[0052] Long Distance Antenna Characterization and Data Collection

[0053] Long distance antenna characterization was carried out in the Tucson Mountain Park area. A mesh structure was designed for deployment on the distal region of the forearm and was comprised of temperature and heart rate recording capabilities. This device was mounted onto the wrist, and the user was instructed to climb to the top of Brown Mountain located at (32.229180, - 111.148863). The wearer also brought a development kit (HTCC-AB01, Cube Cell), which featured a IPEX interface for antenna characterization. A separate development kit was used as the receiver with a commercial 915 MHz monopole for data receiving. This module was placed in a vehicle, enabling rapid relocation at various distances. The distance between the receiver and transmitter was estimated using the FindMy application (Apple). At distances between 0.25 and 15 miles, a sample string containing 20 bytes of information was sent with various LoRa communication parameters. The resulting RSSI and signal-to-noisc ratio values were recorded at each distance for the on-body dipole antenna and the commercially available monopole. After the transmission limitation was found, physiological recordings were collected using the biosymbiotic device with the receiving unit placed at 15 miles from the user. The user was asked to begin transmission during an initial 10 minute resting period, then hike a predetermined path along the brown mountain hiking trail.

[0054] Long-term Data Collection

[0055] A biosymbiotic platform was designed for application onto the distal portion of the forearm and featured a sub millikelvin resolution temperature sensor and an integrated, high- sensitivity pulse oximeter placed near the volar aspect of the wrist. The device was outfitted with a 240 mAh lithium polymer battery. Power casting units (TX91503, Powercast) were placed in key locations of high occupancy, such as the office desk and bedside table. Data aggregation was carried out using a LoRa development module (HTCC-AB01 , Cube Cell) with a 15000 mAh power bank (HYD007, Miady) and a Micro SD card adaptor for data storage. Data was logged as comma separated values and saved onto the SD card. Daily activities including sleep, exercise, time in front of the power casting unit, and other events were recorded into a journal. Battery voltage was measured at regular 8-hour intervals using a digital multimeter (DT132A, AstroAI).

[0056] As used in this application and in the claims, a list of items joined by the term “and/or” can mean any combination of the listed items. For example, the phrase “A, B and/or C” can mean A; B; C; A and B; A and C; B and C; or A, B and C. As used in this application and in the claims, a list of items joined by the term “at least one of’ can mean any combination of the listed terms. For example, the phrases “at least one of A, B or C” can mean A; B; C; A and B; A and C; B and C; or A, B and C.

[0057] As used in any embodiment herein, the terms “system” may refer to, for example, software, firmware and/or circuitry configured to perform any of the aforementioned operations. Software may be embodied as a software package, code, instructions, instruction sets and/or data recorded on non-transitory, computer-readable storage devices. Firmware may be embodied as code, instructions or instruction sets and/or data that are hard-coded (e.g., nonvolatile) in memory devices. “Circuitry”, as used in any embodiment herein, may comprise, for example, singly or in any combination, hardwired circuitry, programmable circuitry such as processors comprising one or more individual instruction processing cores, state machine circuitry, and/or firmware that stores instructions executed by programmable circuitry and/or future computing circuitry including, for example, massive parallelism, analog or quantum computing, hardware embodiments of accelerators such as neural net processors and non- silicon implementations of the above. The circuitry may, collectively or individually, be embodied as circuitry that forms part of a larger system, for example, an integrated circuit (IC), system on-chip (SoC), application-specific integrated circuit (ASIC), programmable logic devices (PLD), digital signal processors (DSP), field programmable gate array (FPGA), logic gates, registers, semiconductor device, chips, microchips, chip sets, etc.

[0058] Any of the operations described herein may be implemented in a system that includes one or more non-transitory storage devices having stored thereon, individually or in combination, instructions that when executed by circuitry perform one or more operations. The instructions may include, for example, machine-executable code, compiled code, instructions sets, etc., and may be in the form of stand-alone instructions and/or part of a larger instruction set such as an application, operating system, virtual operating systems, etc. The circuitry may include any of the aforementioned circuitry including, for examples, one or more processors, ASICs, ICs, etc., and/or other programmable circuitry. Also, it is intended that operations described herein may be distributed across a plurality of physical devices, such as processing structures at more than one different physical location. The storage device includes any type of tangible medium, for example, any type of disk including hard disks, floppy disks, optical disks, compact disk read-only memories (CD-ROMs), compact disk rewritables (CD-RWs), and magneto-optical disks, semiconductor devices such as read-only memories (ROMs), random access memories (RAMs) such as dynamic and static RAMs, erasable programmable read-only memories (EPROMs), electrically erasable programmable read-only memories (EEPROMs), flash memories, Solid State Disks (SSDs), embedded multimedia cards (eMMCs), secure digital input/output (SDIO) cards, magnetic or optical cards, or any type of media suitable for storing electronic instructions. Other embodiments may be implemented as software executed by a programmable control device.

[0059] The terms and expressions which have been employed herein are used as terms of description and not of limitation, and there is no intention, in the use of such terms and expressions, of excluding any equivalents of the features shown and described (or portions thereof), and it is recognized that various modifications are possible within the scope of the claims. Accordingly, the claims arc intended to cover all such equivalents. Various features, aspects, and embodiments have been described herein. The features, aspects, and embodiments are susceptible to combination with one another as well as to variation and modification, as will be understood by those having skill in the art. The present disclosure should, therefore, be considered to encompass such combinations, variations, and modifications.

[0060] Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments.

Claims

WHAT IS CLAIMED:

1. A wearable article, comprising: a base, wherein the base of the article comprises a mesh which is formed of an elastomeric polymer composition; an antenna ground plane structure formed on the base, wherein the ground plane structure comprises mesh which is formed of an elastomeric polymer composition; a dipole antenna structure, wherein the dipole antenna structure comprises mesh which is formed of an elastomeric polymer composition disposed on the ground plane structure; and signal transmission and power harvesting circuitry comprising duplexing circuit to transmit and receive data and to receive wireless power from a power transmission unit.

2. The article of claim 1, wherein the dipole antenna structure is curved in a form of a serpentine shape.

3. The article of claim 2, wherein the serpentine shape is provided by a plurality of 180-degree semi-circular segments.

4. The article of claim 3, wherein the plurality of 180-degree semi-circular segments are of a uniform diameter arranged adjacent one another.

5. The article of claim 1, wherein the antenna ground plane structure and dipole antenna structure are dimensioned to transmit and receive at approximately 915 MHz.

6. The article of claim 1, wherein the elastomeric polymer composition is at least one of a synthetic elastomeric polymer composition and a thermoplastic elastomeric polymer composition.

7. The article of claim 1, wherein the elastomeric polymer composition comprises at least one elastomer, wherein the at least one elastomer is a thermoplastic elastomer.

8. The article of claim 8, wherein the at least one thermoplastic elastomer comprises a thermoplastic urethane elastomer.

9. The article of claim 1, wherein, when disposed on the body, the mesh, the antenna base structure and the antenna dipole structure are flexible and stretchable as to conform to changes in a shape of the body during movement of the body.

10. The article of claim 1, further comprising: at least partially embedding at least one electronic component in the base.

11. The article of claim 10, wherein the at least one electronic component comprises at least one sensor to collect data concerning the wearer when the article is worn by the wearer.

12. The article of claim 11, wherein the at least one sensor comprises at least one of a temperature sensor, and a heart rate sensor.

13. The article of claim 10, wherein the at least one electronic component comprises a wireless transmitter and receiver.

14. The article of claim 10, wherein the at least one electronic component comprises a data collection component.

15. The article of claim 10, wherein the at least one electronic component comprises a wireless communication component.

16. A wearable article, comprising: a base, wherein the base of the article comprises a mesh which is formed of an elastomeric polymer composition; an antenna ground plane structure formed on the base, wherein the ground plane structure comprises mesh which is formed of an elastomeric polymer composition; a dipole antenna structure, wherein the dipole antenna structure comprises mesh which is formed of an elastomeric polymer composition disposed on the ground plane structure; and signal transmission and power harvesting circuitry comprising duplexing circuitry to transmit and receive data with an external unit and to receive wireless power from a power transmission unit; the duplexing circuitry configured to isolate data transmission to the external unit from power transmission from the power transmission unit.

17. The article of claim 16, wherein the dipole antenna structure is curved in a form of a serpentine shape.

18. The article of claim 16, wherein the elastomeric polymer composition is at least one of a synthetic elastomeric polymer composition and a thermoplastic elastomeric polymer composition.

19. The article of claim 16, wherein, when disposed on the body, the mesh, the antenna base structure and the antenna dipole structure are flexible and stretchable as to conform to changes in a shape of the body during movement of the body.

20. The article of claim 16, further comprising: at least partially embedding at least one electronic component in the base.

21. The article of claim 20, wherein the at least one electronic component comprises at least one sensor to collect data concerning the wearer when the article is worn by the wearer.

22. The article of claim 21, wherein the at least one sensor comprises at least one of a temperature sensor, and a heart rate sensor.

23. The article of claim 20, wherein the at least one electronic component comprises a wireless transmitter and receiver.

24. The article of claim 20, wherein the at least one electronic component comprises a data collection component.