Self-powered health monitoring module and method of operation
By designing a self-powered health monitoring module, the photoelectric sensor module and the energy harvesting circuit work together, improving the sensor's sensitivity and anti-interference ability, solving the problems of battery life and accuracy in traditional PPG equipment, and supporting real-time monitoring and transmission of multiple parameters.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- HEFEI UNIV OF TECH
- Filing Date
- 2026-05-11
- Publication Date
- 2026-08-04
AI Technical Summary
Existing PPG health monitoring devices suffer from high power consumption, insufficient sensor sensitivity, weak anti-interference capabilities, limited functionality and accuracy, making it difficult to meet the requirements for low power consumption, non-intrusive data acquisition, continuous monitoring and accurate multi-parameter monitoring.
A self-powered health monitoring module is adopted, including a photoelectric sensor module, a switching control unit, an energy harvesting and power management circuit, a signal processing module, a microcontroller unit, and a wireless communication module. Through the array structure of the photoelectric sensor module and the design of the energy harvesting and power management circuit, combined with the intelligent switching control of the signal processing circuit and the microcontroller, the coordinated operation of energy harvesting and PPG signal acquisition is realized.
It significantly improves the integration and energy efficiency of the device, solves the problem of insufficient battery life of traditional PPG devices, supports accurate monitoring and real-time transmission of multiple parameters, and meets the needs of home health monitoring.
Smart Images
Figure CN122498799A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of health monitoring equipment technology, specifically to a self-powered health monitoring module and its operating method. Background Technology
[0002] Blood pressure is a crucial physiological indicator for assessing cardiovascular health, especially in hospitalized and critically ill patients, where changes directly impact treatment adjustments and prognostic evaluation. Therefore, real-time blood pressure monitoring is essential for early detection of potential threats and timely intervention.
[0003] Besides blood pressure, heart rate is another important parameter for basic health monitoring. Traditional methods of measuring heart rate either rely on electrocardiogram monitors—which require attaching electrodes and are relatively cumbersome to operate—or use simple photoelectric wristbands that can only count roughly.
[0004] In recent years, PPG technology has been increasingly applied in the field of health monitoring due to its non-invasive and continuous monitoring advantages. Its principle utilizes the absorption characteristics of human tissues for specific wavelengths of light; specifically, the absorption of green and red light by hemoglobin in the blood fluctuates with blood flow. PPG signals are collected by photoelectric sensors to indirectly reflect blood flow and pulse characteristics. However, existing health monitoring devices based on PPG technology still have the following key technical shortcomings: Reliance on active light sources: The vast majority of existing PPG devices rely on light-emitting diodes (LEDs) that actively emit light of specific wavelengths as their light source. This "active light emission" mode results in significant power consumption, limiting the device's battery life and contradicting the pursuit of "low power consumption and long battery life" in wearable devices.
[0005] Insufficient sensor sensitivity: Most sensors use traditional silicon-based photodiodes, which have high dark current (≥2nA), making it difficult to capture weak PPG signals in low perfusion states (such as cold fingers and weak blood circulation), resulting in a signal-to-noise ratio (SNR) <30dB, which cannot support subsequent multi-parameter analysis. Weak anti-interference capability: power supply noise margin ≤5V, easily affected by ambient light, electromagnetic interference and motion artifacts, signal distortion rate >15%, especially in outdoor and sports scenarios, the reliability of monitoring data is low; Limited functionality and accuracy: Most devices can only calculate heart rate from the PPG signal cycle and cannot simultaneously analyze blood pressure parameters; a few products that claim to support multi-parameter measurement have large measurement errors and are far from meeting clinical reference standards. Poor environmental adaptability and high system complexity: In scenarios without an external power interface (such as sleep, sports, and outdoor), the device cannot work continuously, limiting application scenarios; additional charging interfaces and protection circuits need to be designed, increasing PCB area and power consumption, which is not conducive to miniaturization integration.
[0006] In summary, current health monitoring devices struggle to simultaneously meet the core requirements of daily health management: low power consumption, non-intrusive data acquisition, continuous monitoring, accurate multi-parameter data collection, and strong anti-interference capabilities. Therefore, developing a multi-parameter PPG health monitoring module that combines high-precision signal acquisition with efficient energy self-sufficiency has significant clinical application value and broad market prospects. Summary of the Invention
[0007] The self-powered health monitoring module proposed in this invention can at least solve one of the technical problems in the background art.
[0008] To achieve the above objectives, the present invention adopts the following technical solution: A self-powered health monitoring module includes: a photoelectric sensor module, a switching control unit, an energy harvesting and power management circuit, a signal processing module, a microcontroller unit, and a wireless communication module; The photoelectric sensor module is connected to the switching control unit, the switching control unit is connected to the signal processing module and the energy harvesting and power management circuit, the signal processing module is connected to the microcontroller, and the microcontroller is connected to the wireless communication module. The photoelectric sensor module includes eight photodiodes configured to receive the photoplethysmography (PPG) signal of the object under test in the first operating mode. The energy harvesting and power management circuit is electrically connected to the photoelectric sensor module, configured to perform photoelectric conversion in the second working mode, and store the energy in the energy storage unit; The signal processing module is electrically connected to the photoelectric sensor module and is configured to perform photoplethysmography (PPG) signal processing in the first working mode. The microcontroller unit is electrically connected to the signal processing circuit and the switching control unit.
[0009] Furthermore, the photoelectric sensor module of the present invention adopts an array structure and has eight photosensitive units: eight photodiodes etched on a single-crystal silicon substrate in a quadrantal distribution and electrically isolated from each other; The eight photosensitive units are connected in parallel in the circuit.
[0010] Furthermore, the energy harvesting and power management circuit of the present invention includes: an energy harvesting unit and a power management unit; The energy harvesting unit structure includes: one end of capacitor CREF is connected to the fourth pin of energy harvesting chip U1, and the other end is connected to GND; One end of capacitor CIN is connected to the second pin of energy harvesting chip U1, and the other end is connected to GND; One end of capacitor CBYP and capacitor CSTOR are connected together to pin 3 of U1, and the other end is connected to GND. Pin 19 of energy harvesting chip U1 is connected to pin 3. One end of lithium battery is connected to pin 18 of energy harvesting chip U1, and the other end is connected to GND. One end of capacitor COUT is connected to one end of inductor L2, and the other end is connected to GND. The other end of inductor L2 is connected to pin 16 of energy harvesting chip U1. The two ends of inductor L1 are connected to the second and twentieth pins of energy harvesting chip U1, and the sixth and thirteenth pins of energy harvesting chip U1 are connected. One end of resistors ROV2, ROK3, and ROUT2 is connected to the eighth pin of energy harvesting chip U1. The other end of resistor ROV2 and one end of resistor ROV1 are connected to the seventh pin of energy harvesting chip U1. The other end of resistor ROK3 and one end of resistor ROK2 are connected to the tenth pin of energy harvesting chip U1. The other end of resistor ROK2 and one end of resistor ROK1 are connected to the eleventh pin of U1. The other end of resistor ROUT2 and one end of resistor ROUT1 are connected to the twelfth pin of energy harvesting chip U1. The other ends of resistors ROV1, ROK1, and ROUT1 are all connected to GND.
[0011] Furthermore, the signal processing circuit of the present invention includes: a low-noise operational amplifier, an AC-coupled amplifier, a multi-stage bandpass filter, a programmable gain amplifier, and an analog-to-digital converter connected in sequence; The analog PPG raw signal is pre-amplified by a small factor using a low-noise operational amplifier, while removing inherent circuit noise and coupling interference. Then, the DC component is blocked by a DC blocking capacitor using an AC coupling amplifier, and the DC bias component is filtered out. At the same time, a fixed gain is set for the AC coupling amplifier, and the effective AC signal is amplified by a fixed ratio to increase the signal amplitude to the input level range of the multi-stage bandpass filter. The bias components include: sensor temperature drift, DC offset caused by baseline drift, and ambient DC light intensity.
[0012] Furthermore, the signal processing circuit structure of the present invention includes: The output signal SWOUT of the transimpedance amplifier ADA4350 is coupled to the non-inverting input of U7A through capacitor C32. The connection point between capacitor C32 and the non-inverting input of operational amplifier unit U7A is connected to AGND through resistor R22. AGND is connected to the inverting input of U7A through resistor R21. Resistor R23 is connected across the output and inverting input of U7A to form a feedback loop. The positive power supply terminal of the operational amplifier unit U7A is connected to +3.3V, and the negative power supply terminal is connected to -3.3V; The output of operational amplifier unit U7A is coupled to the non-inverting input of U7B via capacitor C33. The connection point between capacitor C33 and pin 5 of U7B is connected to AGND via resistor R25. AGND is connected to the inverting input of U7B via resistor R24. Resistor R26 is connected across the output and inverting input of operational amplifier unit U7B to form a feedback loop. The output of operational amplifier unit U7B is connected to the output of operational amplifier unit U7C via resistor R27. The other path is connected to the non-inverting input of operational amplifier unit U7C via resistor R29. The connection point between resistor R29 and pin 12 of U7C is connected to AGND via capacitor C35. AGND is connected to the inverting input of operational amplifier unit U7C via resistor R28. Resistor R30 is connected across the output and inverting input of operational amplifier unit U7C to form a feedback loop. The output of operational amplifier unit U7C is connected to AGND via resistor R31 and capacitor C36. Another path is connected to the inverting input of operational amplifier unit U7D via resistor R33. The connection point of resistors R31 and R33 is connected to the output of U7D via resistor R32. The non-inverting input of the operational amplifier unit U7D is directly connected to AGND, and capacitor C37 is connected across the output and inverting input of U7D to form a feedback loop. The output terminal of U7D is the circuit output signal AIN; In addition, the redundant pin U7E of the LT6005 chip is directly connected to AGND, with no signal connection. The V+ terminal of the programmable gain amplifier LTC6910 is connected to +3.3V, and the V- terminal is connected to -3.3V. The output signal AIN of amplifier LT6005 is connected to IN of programmable gain amplifier LTC6910, and the output signal PAMPOUT is led out from OUT of programmable gain amplifier LTC6910. The gain control terminals G0, G1, and G2 are external control signal interfaces used to set the gain level of the amplifier.
[0013] In another aspect, the present invention provides a method for operating a self-powered health monitoring module, the method comprising: The module selects the energy harvesting mode, the photoelectric sensor module is connected to the energy harvesting circuit, and the BQ25570 chip collects and stores the input electrical energy in the lithium battery. When a threshold is reached, the BQ25570 will stop collecting electrical energy. The module switches to physiological monitoring mode, the photoelectric sensor module is connected to the signal processing circuit, the prepared detector is placed on the fingertip, and the ambient light is used for transmission measurement; The generated weak PPG current signal is first processed by the signal processing circuit: it is converted into voltage by the transimpedance amplifier, then the baseline drift is suppressed by the AC coupling amplifier, then the high-frequency noise is filtered out by the multi-stage bandpass filter, and finally the signal gain is dynamically adjusted by the programmable gain amplifier. The processed signal is acquired by the microcontroller's ADC, which converts the PPG voltage signal into a PPG digital signal; Within the microcontroller, heart rate, respiratory rate, and blood pressure values are extracted using frequency domain analysis and deep learning models, respectively. Finally, the heart rate, respiratory rate, and blood pressure values are sent to the PC for display via the WiFi module.
[0014] In summary, this invention achieves coordinated operation of energy harvesting and PPG signal acquisition through the dual-mode multiplexing design of the photoelectric sensor module, eliminating the need for additional energy harvesting devices and significantly improving the integration and energy utilization efficiency of the device. The photoelectric sensor adopts an array structure, which maximizes the effective receiving area and conversion efficiency of the light-sensing region without significantly increasing the device area, thus significantly improving the anti-interference capability of the acquired PPG.
[0015] The ultra-low power hardware architecture and intelligent switching control enable the device to achieve continuous standby monitoring under ambient light, solving the problem of insufficient battery life of traditional PPG devices. The integrated WiFi low-power module and algorithm analysis function support real-time transmission of physiological parameters and abnormal warnings, meeting the needs of home health monitoring. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of the health monitoring circuit module of the present invention; Figure 2 This is a schematic diagram of the photoelectric sensor in the health monitoring circuit module of the present invention; Figure 3 This is a schematic diagram of the energy harvesting circuit in the health monitoring circuit module of the present invention; Figure 4 This is a schematic diagram of the power management circuit in the health monitoring circuit module of the present invention; Figure 5 This is a schematic diagram of the AC coupling amplifier, multi-stage bandpass filter, and programmable gain amplifier circuit in the health monitoring circuit module of this invention; Figure 6 This is a schematic diagram of the transimpedance amplifier circuit in the health monitoring circuit module of the present invention; Figure 7 This is a schematic diagram of the switching control circuit in the health monitoring circuit module of the present invention; Figure 8 This is a schematic diagram of the microcontroller circuit in the health monitoring circuit module of the present invention; Figure 9 This is a schematic diagram of the wireless communication module in the health monitoring circuit module of the present invention; Figure 10 This is a schematic diagram illustrating the working process of the health monitoring circuit module of the present invention. Detailed Implementation
[0017] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments.
[0018] like Figure 1 As shown, the self-powered health monitoring module described in this embodiment includes: a photoelectric sensor module, a switching control unit (analog switch), an energy harvesting and power management circuit, a signal processing module, a microcontroller unit, and a wireless communication module; The photoelectric sensor module is connected to the switching control unit (analog switch), the switching control unit is connected to the signal processing module and the energy harvesting and power management circuit, the signal processing module is connected to the microcontroller, and the microcontroller is connected to the wireless communication module.
[0019] The photoelectric sensor module contains eight photodiodes configured to receive photoplethysmography (PPG) signals from the object under test in a first operating mode and to collect ambient light energy in a second operating mode. Energy harvesting and power management circuit: electrically connected to the photoelectric sensor module, used to convert ambient light energy into electrical energy and store it in the energy storage unit in the second working mode, and to provide reliable power supply for the back-end circuit; Signal processing module: electrically connected to the photoelectric sensor module, used to filter, amplify, and perform analog-to-digital conversion on the PPG signal in the first working mode to extract physiological parameters; Switching control unit: used to automatically switch the electrical connection of the photoelectric sensor module between the first operating mode and the second operating mode; Microcontroller unit: electrically connected to the signal processing circuit and the switching control unit, used to store physiological parameter data, perform algorithm analysis, and control the working mode of the switching control unit.
[0020] The wireless communication module communicates with the microcontroller via UART to enable real-time wireless data transmission to the PC.
[0021] The photoelectric sensor module adopts an array structure with eight photosensitive units: eight photodiodes etched on a single-crystal silicon substrate, arranged in quadrants and electrically isolated from each other; the eight photosensitive units are connected in parallel in the circuit.
[0022] The energy harvesting and management circuit uses a dedicated energy harvesting chip, model BQ25570, which collects and stores the input electrical energy in the energy storage unit.
[0023] The signal processing circuit uses a low-noise operational amplifier, an AC-coupled proportional amplifier, a multi-stage bandpass filter, a programmable gain amplifier, and an analog-to-digital converter, all cascaded in the order described above. This further amplifies, filters, and digitizes the PPG signal received by the photoelectric sensor module, generating a digitized PPG signal.
[0024] The analog PPG raw signal is pre-amplified by a small factor using a low-noise operational amplifier, while removing inherent circuit noise and coupling interference. Then, the DC component is blocked by a DC blocking capacitor using an AC coupling amplifier, and the DC bias component is filtered out. At the same time, a fixed gain is set for the AC coupling amplifier, and the effective AC signal is amplified by a fixed ratio to increase the signal amplitude to the input level range of the multi-stage bandpass filter. The bias components include: sensor temperature drift, DC offset caused by baseline drift, and ambient DC light intensity.
[0025] The switching control unit uses a single-pole double-throw analog switch (model SGM3003), which is controlled by the GPIO pin of the microcontroller unit to switch between the photoelectric sensor module and the energy harvesting circuit or signal processing circuit.
[0026] The microcontroller unit uses the STM32F103C8T6, which integrates an ADC module, communication interface, and patent code protection (PCROP) unit for signal digitization, data transmission, and algorithm protection.
[0027] The wireless communication module uses a WiFi module and communicates with the microcontroller via UART to achieve real-time data transmission to the PC.
[0028] The specific structure of each module is as follows: The photoelectric sensing module uses a silicon-based photodiode array as a photoelectric sensor.
[0029] like Figure 2As shown, a single-crystal silicon substrate is used. On the upper surface of the single-crystal silicon substrate, eight photodiodes are formed in a quadrant distribution and electrically isolated from each other by laser etching mask and physical vapor deposition, forming eight identical photosensitive units. The eight photosensitive units are connected in parallel in the circuit to linearly increase the effective photosensitive area and improve the photocurrent, while not increasing the dark current proportionally, thereby achieving synergistic optimization of the signal-to-noise ratio.
[0030] This sensor uses Ti-Al electrodes, which have rectifying and low resistivity properties, to generate a self-powered photocurrent under ambient light. By operating under ambient light, it can acquire high-quality PPG signals. At a wavelength of 635nm and in self-powered mode, its responsivity is no less than 0.5A / W, and its dark current is in the picoampere range.
[0031] like Figure 3 As shown, the energy harvesting circuit structure is as follows. This circuit consists of a BQ25570 energy harvesting chip U1, a lithium battery, inductors L1 and L2, resistors ROV1, ROV2, ROK1, ROK2, ROK3, ROUT1, ROUT2, and capacitors CIN, CBYP, CSTOR, CREF, and COUT. Pins 1, 5, 17, 9, 15, and 21 of U1 are connected to GND.
[0032] One end of capacitor CREF is connected to pin 4 of U1, and the other end is connected to GND. One end of capacitor CIN is connected to pin 2 of U1, and the other end is connected to GND. One end of capacitors CBYP and CSTOR are connected together to pin 3 of U1, and the other end is connected to GND. Pins 19 and 3 of U1 are also connected. One end of the lithium battery is connected to pin 18 of U1, and the other end is connected to GND. One end of capacitor COUT is connected to one end of inductor L2, and the other end is connected to GND. The other end of L2 is connected to pin 16 of U1. The two ends of inductor L1 are connected to pins 2 and 20 of U1, and pins 6 and 13 of U1. Connect one end of resistors ROV2, ROK3, and ROUT2 together to pin 8 of U1. Connect the other end of ROV2 and one end of ROV1 to pin 7 of U1. Connect the other end of ROK3 and one end of ROK2 to pin 10 of U1. Connect the other end of ROK2 and one end of ROK1 to pin 11 of U1. Connect the other end of ROUT2 and one end of ROUT1 to pin 12 of U1. Connect the other ends of ROV1, ROK1, and ROUT1 to GND.
[0033] This embodiment uses the BQ25570 chip to capture ambient light energy and then uses it to generate power for other circuits. The BQ25570 is an ultra-low-power, highly integrated energy harvesting chip, primarily used for efficiently harvesting and managing weak ambient energy (μW to mW levels). The electrical energy generated by the optoelectronic device serves as the input to the entire energy harvesting and power management circuit. The BQ25570 chip collects and stores this input energy in a lithium battery. When a threshold is reached, the BQ25570 stops harvesting energy. This threshold is the fully charged voltage threshold of the lithium battery, which can be set according to application requirements. The voltage threshold is set according to the following formula: VBAT_OV=1.5*VBIAS*(1+R OV2 / R OV1 ), where the value of VBIAS is 1.21V (the same applies below).
[0034] In this embodiment, the lithium battery's fully charged voltage threshold is set to 4.2V. The chip has power management capabilities; by adjusting the corresponding resistors, the system's supply voltage can be regulated. The voltage regulation satisfies the following formula: VOUT=VBIAS*(1+R OUT2 / R OUT1 ); VBAT_OK_PROG=VBIAS*(1+R Ok2 / R Ok1 ); VBAT_OK_HYST=VBIAS*(1+R Ok2 / R Ok1 +R Ok3 / R Ok1 ); Based on the lithium battery voltage threshold and other circuit operating voltages, set VOUT=3.73V, VBAT_OV=4.235V, VBAT_OK_PROG=3.73V, and VBAT_OK_HYST=4.006V.
[0035] like Figure 4 As shown, the power management circuit mainly consists of an ME6211 voltage regulator chip and an LM27762 charge pump chip. The output terminal of the ME6211 voltage regulator chip is connected to the input terminal EN of the LM27762 charge pump chip. The power management circuit converts the input voltage into a stable ±3.3V DC voltage and has overcurrent and overvoltage protection functions, providing reliable power supply for the downstream circuits.
[0036] like Figure 5As shown, the signal processing circuit includes: a transimpedance amplifier, an AC-coupled amplifier, a multi-stage bandpass filter, a programmable gain amplifier, and an analog-to-digital converter (ADC). First, the transimpedance amplifier filters and amplifies the weak signal output from the photoelectric sensor. Then, an AC-coupled proportional amplifier and a multi-stage bandpass filter further amplify and filter the optical signal received by the photoelectric sensor module. Next, the programmable gain amplifier adjusts the signal amplitude, and finally, the signal is converted into a PPG digital signal by the ADC.
[0037] The signal processing circuit structure is as follows: It consists of an LT6005 quad op-amp chip (containing four op-amp units: U7A, U7B, U7C, and U7D), a programmable gain amplifier LTC6910 (U8), resistors, and capacitors.
[0038] The connections of each component are as follows: The output signal SWOUT of the transimpedance amplifier ADA4350 is coupled to the non-inverting input (pin 3) of U7A via capacitor C32. The connection point between capacitor C32 and the non-inverting input of op-amp unit U7A is simultaneously connected to AGND via resistor R22. AGND is connected to the inverting input (pin 2) of U7A via resistor R21. Resistor R23 is connected between the output (pin 1) and the inverting input (pin 2) of U7A to form a feedback loop. The positive power supply terminal (pin 4) of op-amp unit U7A is connected to +3. The -3V, negative power supply terminal (pin 13) is connected to -3.3V; the output terminal (pin 1) of U7A is coupled to the non-inverting input terminal (pin 5) of U7B via capacitor C33. The connection point between capacitor C33 and pin 5 of U7B is simultaneously connected to AGND via resistor R25. AGND is connected to the inverting input terminal (pin 6) of U7B via resistor R24. Resistor R26 is connected across the output terminal (pin 7) and the inverting input terminal (pin 6) of U7B to form a feedback loop; the output terminal (pin 7) of U7B is connected to capacitor C34 via resistor R27. The output terminal (pin 10) of U7C has one path connected to the non-inverting input terminal (pin 12) of U7C via resistor R29. The connection point between resistor R29 and pin 12 of U7C is simultaneously connected to AGND via capacitor C35. AGND is then connected to the inverting input terminal (pin 11) of U7C via resistor R28. Resistor R30 is connected across the output terminal (pin 10) and the inverting input terminal (pin 11) of U7C to form a feedback loop. The output terminal (pin 10) of U7C, after passing through resistor R31, has one path connected to AGND via capacitor C36, and the other path connected to resistor R... 33 is connected to the inverting input terminal (pin 15) of U7D. The connection point of R31 and R33 is simultaneously connected to the output terminal (pin 16) of U7D via resistor R32. The non-inverting input terminal (pin 14) of U7D is directly connected to AGND. Capacitor C37 is connected across the output terminal (pin 16) and the inverting input terminal (pin 15) of U7D to form a feedback loop. The output terminal (pin 16) of U7D is the circuit output signal AIN. In addition, the redundant pins U7E (EP, NC) of the LT6005 chip are directly connected to AGND and have no signal connection. The programmable gain amplifier LTC6910 (U8) has its V+ (pin 8) connected to +3.3V, V- (pin 4) connected to -3.3V, and AGND (pin 2) connected to AGND. The output signal AIN of LT6005 (U7) is connected to IN (pin 3) of U8, and the output signal PAMPOUT is brought out from OUT (pin 1) of U8. The gain control terminals G0 (pin 5), G1 (pin 6), and G2 (pin 7) are external control signal interfaces used to set the gain level of the amplifier.
[0039] like Figure 6 As shown, the transimpedance amplifier is built using the low-noise operational amplifier ADA4350 to achieve high gain and low noise in current-to-voltage conversion.
[0040] An AC-coupled amplifier and a multi-stage bandpass filter are used to further amplify and filter the optical signal received by the photoelectric sensor module. The AC-coupled proportional amplifier is used to suppress the baseline drift of the PPG voltage signal, filter out DC components, power frequency interference and high-frequency noise, and retain only the effective frequency band containing vital signs information.
[0041] The programmable gain amplifier uses the LTC6910 to dynamically adjust the signal gain, thereby optimizing the dynamic range of the signal link, improving measurement accuracy, and realizing functions such as automatic gain control.
[0042] Analog-to-digital converter: Converts the filtered PPG voltage signal into a PPG digital signal for subsequent algorithm processing.
[0043] like Figure 7 As shown, the switching control unit uses an SGM3003 single-pole double-throw analog switch, which is controlled by the GPIO pin of the STM32F103C8T6 microcontroller to realize the switching between the photoelectric sensor module and the energy harvesting circuit or signal processing circuit. Energy harvesting mode: When the device is idle, the STM32F103C8T6 microcontroller GPIO outputs a low level, and the SGM3003 single-pole double-throw analog switch controls the connection between the photoelectric sensor module and the BQ25570 energy harvesting circuit.
[0044] Physiological monitoring mode: When the user triggers the monitoring command, the STM32F103C8T6 microcontroller GPIO outputs a high level, and the SGM3003 single-pole double-throw analog switch controls the connection between the photoelectric sensor module and the signal processing circuit.
[0045] like Figure 8 As shown, the microcontroller unit uses an STM32F103C8T6 microcontroller to convert the filtered and amplified PPG signal into a digital signal through a high-precision ADC; heart rate and respiratory rate are extracted from the PPG digital signal in real time using Fast Fourier Transform (FFT); and the digitized PPG signal is then input into a pre-trained neural network model (CNN) to predict blood pressure values.
[0046] like Figure 9 As shown, the wireless communication module uses an ESP8266 module, which connects to an STM32F103C8T6 microcontroller via a UART interface to achieve wireless data transmission, used to send heart rate, respiratory rate and blood pressure values to the PC for display.
[0047] like Figure 10 As shown, the workflow of the health monitoring circuit module is as follows: In energy harvesting mode, the photoelectric sensor module is connected to the energy harvesting circuit, and the BQ25570 chip collects and stores the input electrical energy in the lithium battery. When a threshold is reached, the BQ25570 will stop collecting electrical energy. In physiological monitoring mode, the photoelectric sensor module is connected to the signal processing circuit. The fabricated detector is placed on the fingertip, and transmission measurement is performed using ambient light. The generated weak PPG current signal is first processed by the signal processing circuit: it is converted into a voltage by a transimpedance amplifier, then baseline drift is suppressed by an AC coupling amplifier, high-frequency noise is filtered out by a multi-stage bandpass filter, and finally the signal gain is dynamically adjusted by a programmable gain amplifier. The processed signal is acquired by the microcontroller's ADC, which converts the PPG voltage signal into a PPG digital signal. Within the microcontroller, heart rate, respiratory rate, and blood pressure values can be reliably extracted using frequency domain analysis (FFT) and a deep learning model (CNN), respectively. Finally, the heart rate, respiratory rate, and blood pressure values are transmitted to a PC for display via a WiFi module.
[0048] Tests showed that the health monitoring module can achieve continuous standby monitoring for 30 days under 100 lux ambient light; the heart rate measurement error is ≤2 bpm; and the lightweight convolutional neural network (CNN) model trained on the MIMIC-Ⅲ public dataset meets the standards of the American Association for the Advancement of Medical Devices (AAMI) (mean error ≤5 mmHg, standard deviation ≤8 mmHg) and the British Hypertension Society (BHS) Class A standard.
[0049] In summary, this invention achieves coordinated operation of energy harvesting and PPG signal acquisition through the dual-mode multiplexing design of the photoelectric sensor module, eliminating the need for additional energy harvesting devices and significantly improving the integration and energy utilization efficiency of the device. The photoelectric sensor adopts an array structure, which maximizes the effective receiving area and conversion efficiency of the light-sensing region without significantly increasing the device area, thus significantly improving the anti-interference capability of the acquired PPG.
[0050] The ultra-low power hardware architecture and intelligent switching control enable the device to achieve continuous standby monitoring under ambient light, solving the problem of insufficient battery life of traditional PPG devices. The integrated WiFi low-power module and algorithm analysis function support real-time transmission of physiological parameters and abnormal warnings, meeting the needs of home health monitoring.
[0051] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0052] The various embodiments in this specification are described in a related manner. Similar or identical parts between embodiments can be referred to mutually. Each embodiment focuses on describing the differences from other embodiments. In particular, the system embodiments are basically similar to the method embodiments, so the description is relatively simple; relevant parts can be referred to the descriptions of the method embodiments.
[0053] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A self-powered health monitoring module, characterized in that, This module includes: a photoelectric sensor module, a switching control unit, an energy harvesting and power management circuit, a signal processing module, a microcontroller unit, and a wireless communication module; The photoelectric sensor module is connected to the switching control unit, the switching control unit is connected to the signal processing module and the energy harvesting and power management circuit, the signal processing module is connected to the microcontroller, and the microcontroller is connected to the wireless communication module. The photoelectric sensor module includes eight photodiodes configured to receive the photoplethysmography (PPG) signal of the object under test in the first operating mode. The energy harvesting and power management circuit is electrically connected to the photoelectric sensor module, configured to perform photoelectric conversion in the second working mode, and store the energy in the energy storage unit; The signal processing module is electrically connected to the photoelectric sensor module and is configured to perform photoplethysmography (PPG) signal processing in the first working mode. The microcontroller unit is electrically connected to the signal processing circuit and the switching control unit.
2. The multi-parameter health monitoring module based on the photoplethysmographic technique according to claim 1, wherein, The photoelectric sensor module adopts an array structure with eight photosensitive units: eight photodiodes etched on a single-crystal silicon substrate, arranged in quadrants and electrically isolated from each other; The eight photosensitive units are connected in parallel in the circuit.
3. The self-powered health monitoring module of claim 1, wherein, The energy harvesting and power management circuit includes: an energy harvesting unit and a power management unit; The energy harvesting unit structure includes: one end of capacitor CREF is connected to the fourth pin of energy harvesting chip U1, and the other end is connected to GND; One end of capacitor CIN is connected to the second pin of energy harvesting chip U1, and the other end is connected to GND; One end of capacitor CBYP and capacitor CSTOR are connected together to pin 3 of U1, and the other end is connected to GND. Pin 19 of energy harvesting chip U1 is connected to pin 3. One end of lithium battery is connected to pin 18 of energy harvesting chip U1, and the other end is connected to GND. One end of capacitor COUT is connected to one end of inductor L2, and the other end is connected to GND. The other end of inductor L2 is connected to pin 16 of energy harvesting chip U1. The two ends of inductor L1 are connected to the second and twentieth pins of energy harvesting chip U1, and the sixth and thirteenth pins of energy harvesting chip U1 are connected. One end of resistors ROV2, ROK3, and ROUT2 is connected to the eighth pin of energy harvesting chip U1. The other end of resistor ROV2 and one end of resistor ROV1 are connected to the seventh pin of energy harvesting chip U1. The other end of resistor ROK3 and one end of resistor ROK2 are connected to the tenth pin of energy harvesting chip U1. The other end of resistor ROK2 and one end of resistor ROK1 are connected to the eleventh pin of U1. The other end of resistor ROUT2 and one end of resistor ROUT1 are connected to the twelfth pin of energy harvesting chip U1. The other ends of resistors ROV1, ROK1, and ROUT1 are all connected to GND.
4. The self-powered health monitoring module of claim 1, wherein, The signal processing circuit includes: a low-noise operational amplifier, an AC-coupled amplifier, a multi-stage bandpass filter, a programmable gain amplifier, and an analog-to-digital converter connected in sequence; The analog PPG raw signal is pre-amplified by a small factor using a low-noise operational amplifier, while removing inherent circuit noise and coupling interference. Then, the DC component is blocked by a DC blocking capacitor using an AC coupling amplifier, and the DC bias component is filtered out. At the same time, a fixed gain is set for the AC coupling amplifier, and the effective AC signal is amplified by a fixed ratio to increase the signal amplitude to the input level range of the multi-stage bandpass filter. The bias components include: sensor temperature drift, DC offset caused by baseline drift, and ambient DC light intensity.
5. The self-powered health monitoring module of claim 4, wherein, The signal processing circuit structure includes: The output signal SWOUT of the transimpedance amplifier ADA4350 is coupled to the non-inverting input of U7A through capacitor C32. The connection point between capacitor C32 and the non-inverting input of the operational amplifier unit U7A is connected to AGND through resistor R22. AGND is connected to the inverting input of U7A through resistor R21. Resistor R23 is connected across the output and inverting input of U7A to form a feedback loop. The positive power supply terminal of the operational amplifier unit U7A is connected to +3.3V, and the negative power supply terminal is connected to -3.3V; The output of operational amplifier unit U7A is coupled to the non-inverting input of U7B via capacitor C33. The connection point between capacitor C33 and pin 5 of U7B is connected to AGND via resistor R25. AGND is connected to the inverting input of U7B via resistor R24. Resistor R26 is connected across the output and inverting input of operational amplifier unit U7B to form a feedback loop. The output of operational amplifier unit U7B is connected to the output of operational amplifier unit U7C via resistor R27. The other path is connected to the non-inverting input of operational amplifier unit U7C via resistor R29. The connection point between resistor R29 and pin 12 of U7C is connected to AGND via capacitor C35. AGND is connected to the inverting input of operational amplifier unit U7C via resistor R28. Resistor R30 is connected across the output and inverting input of operational amplifier unit U7C to form a feedback loop. The output of operational amplifier unit U7C is connected to AGND via resistor R31 and capacitor C36. Another path is connected to the inverting input of operational amplifier unit U7D via resistor R33. The connection point of resistors R31 and R33 is connected to the output of U7D via resistor R32. The non-inverting input of the operational amplifier unit U7D is directly connected to AGND, and capacitor C37 is connected across the output and inverting input of U7D to form a feedback loop. The output terminal of U7D is the circuit output signal AIN; In addition, the redundant pin U7E of the LT6005 chip is directly connected to AGND, with no signal connection. The V+ terminal of the programmable gain amplifier LTC6910 is connected to +3.3V, and the V- terminal is connected to -3.3V. The output signal AIN of amplifier LT6005 is connected to IN of programmable gain amplifier LTC6910, and the output signal PAMPOUT is led out from OUT of programmable gain amplifier LTC6910. The gain control terminals G0, G1, and G2 are external control signal interfaces used to set the gain level of the amplifier.
6. A method for operating a self-powered health monitoring module, characterized in that, The methods include: Module selection energy collection mode, photoelectric sensor module is connected with energy collection circuit, BQ25570 chip will input the energy collection stored in lithium battery, when storage to a threshold, BQ25570 will stop collecting electric energy; Module switches to physiological monitoring mode, photoelectric sensor module is connected with signal processing circuit, the prepared detector is placed in the fingertip, and the ambient light is used for transmission type measurement; The generated weak PPG current signal is first processed by the signal processing circuit: converted into voltage by the transimpedance amplifier, and then the baseline drift is suppressed by the AC coupling amplifier, and then the high frequency noise is filtered by the multi-stage band pass filter, and finally the signal gain is dynamically adjusted by the programmable gain amplifier; The processed signal is collected by the ADC of the microcontroller, and the PPG voltage signal is converted into PPG digital signal; In the microcontroller, the heart rate, respiratory rate and blood pressure values are extracted through frequency domain analysis and deep learning model respectively; Finally, the heart rate, respiratory rate and blood pressure values are sent to the PC end display through the WiFi module.