Sweat sensing integrated circuit system based on ultrasonic driving and signal processing

Abstract

The invention discloses a sweat sensing integrated circuit system based on ultrasonic driving and signal processing. Comprising a power management module, a driving signal generation and amplification module, a sensor signal processing module, a control and communication module, a display and storage module and the like. A main circuit topology and a control circuit of a power management module in the system work cooperatively, 220V AC is stably converted into a DC power supply suitable for system operation, and the power supply stability is improved; the driving signal generation and amplification module adopts an AD9833 chip and the like to accurately generate and amplify a driving signal, so that the driving requirements of different transducers are met; the sensor signal processing module amplifies and processes sweat sensor signals by using a high-performance operational amplifier and the like and monitors environmental factors in real time in combination with a temperature and humidity sensor, so that the detection precision and reliability are improved; the low-noise anti-interference sweat detection function is achieved, multi-parameter monitoring and high-power adjustable output are supported, development of wearable medical equipment is promoted, and the health monitoring level is improved.

Description

Technical Field

[0001] The present invention relates to a sweat sensing integrated circuit system based on ultrasonic driving and signal processing. Background Art

[0002] At the intersection of ultrasound and circuit technology, sweat sensing integrated circuit systems hold significant promise for applications such as wearable medical devices and health monitoring. However, existing technologies present numerous challenges. Regarding detection accuracy, conventional sweat sensing systems struggle to suppress noise interference due to circuit design flaws in the signal processing phase. Weak sweat signals are easily overwhelmed by noise, resulting in large detection errors and failing to meet the demand for high-precision sweat component detection. Furthermore, existing systems lack effective anti-interference measures in complex electromagnetic environments, making external electromagnetic interference susceptible to sensor signal acquisition and processing, reducing system reliability. Furthermore, they struggle to simultaneously monitor multiple parameters, and the driver circuit's output power adjustment range is narrow, making it incompatible with diverse sensors and transducers. Furthermore, conventional designs suffer from low efficiency and high energy loss, making it difficult to maintain stable power supply even when the input voltage fluctuates, increasing device power consumption and operating costs. Therefore, the development of high-precision, low-noise, and interference-resistant sweat sensing integrated circuit systems capable of multi-parameter monitoring and high-power adjustable output is crucial for advancing the development of wearable medical devices and improving health monitoring capabilities. Summary of the Invention

[0003] Purpose of the invention: The purpose of the present invention is to provide a sweat sensing integrated circuit system based on ultrasonic drive and signal processing that can achieve high-precision, low-noise, and anti-interference sweat detection functions, and supports multi-parameter monitoring and high-power adjustable output.

[0004] Technical solution: The sweat sensing integrated circuit system based on ultrasonic drive and signal processing described in the present invention includes a power management module, a drive signal generation and amplification module, a sensor signal processing module, a control and communication module, and a display and storage module;

[0005] The power management module includes a main circuit half-bridge topology and a control circuit;

[0006] The drive signal generation and amplification module includes a sine wave generation circuit, a sine wave signal amplification circuit, a sine wave to square wave circuit, a frequency division phase shift circuit, a high-speed optocoupler circuit, a full-bridge inverter circuit, a current mutual induction circuit and an effective value calculation circuit;

[0007] The sensor signal processing module includes a sensor signal amplification circuit, a voltage inversion circuit and a temperature and humidity sensor working circuit;

[0008] The control and communication module includes a USB to serial port circuit and an STM32 peripheral circuit;

[0009] The display and storage module includes an OLED circuit and a data storage circuit.

[0010] Furthermore, the main circuit half-bridge topology includes a DC input voltage, an inverter stage and an RCD absorption circuit;

[0011] The control circuit includes a PWM controller, a driving circuit and a feedback network.

[0012] Furthermore, the DC input voltage in the half-bridge topology of the main circuit is converted from 220V AC to 310V DC after passing through an EMI filter, a bridge rectifier, and a filter capacitor, and then divided by a resistor to 155V DC;

[0013] The inverter stage is two switching tubes connected in series, with the midpoint connected to the primary end of the high-frequency transformer. The secondary of the transformer adopts full-wave rectification and LC filtering.

[0014] The RCD absorption circuit is connected in parallel across Q4 / Q5 to absorb leakage inductance energy.

[0015] Furthermore, the drive signal generation and amplification module uses the chip AD9833 to generate a sinusoidal signal of the required frequency. When a 25MHz system clock is used, the frequency range of the AD9833 output signal is 0-12.5MHz, and the minimum frequency step is 0.1Hz.

[0016] Furthermore, the sine wave generating circuit uses DDS technology, sets the frequency control word (M) through the SPI interface, reads 4096 pre-stored sine wave sampling points from the internal ROM lookup table to generate a waveform, and then converts it into an analog voltage through a 10-bit DAC. The theoretical maximum frequency is 12.5MHz. If high-frequency distortion occurs, an external low-pass filter can be used.

[0017] The sine wave signal amplification circuit uses an AD797 operational amplifier to amplify the signal, and the amplification factor of the operational amplifier is changed by adjusting the adjustable resistor R15 located between the output terminal pin 6 and the negative input terminal pin 2;

[0018] The sine wave to square wave circuit uses the voltage comparator TLV3501 to convert the sine wave amplified by the operational amplifier AD797 into a square wave; by adjusting the adjustable resistor R16, the threshold value of the comparison voltage is changed to adjust the duty cycle of the output square wave signal;

[0019] The frequency division phase shift circuit applies a frequency division phase shift circuit composed of an inverter SN74LS14N, a JK flip-flop CD4027 and a 3-input NAND gate SN74HC11N to the output signal of the TLV3501 to divide the square wave signal output by the voltage comparator TLV3501 by two, thereby obtaining a center-aligned complementary square wave signal;

[0020] The high-speed optocoupler circuit uses the high-speed optocoupler 6N137 to separate the analog circuit from the digital circuit;

[0021] An RCD absorption circuit is connected in parallel between the source and drain of the four N-channel MOS tubes Q1 / Q2 / Q3 / Q4 of the full-bridge inverter circuit;

[0022] The current mutual inductance circuit adopts electric feedback, and the primary of its peripheral circuit is connected to the networks VS1 and VS2, one end of the secondary is connected to DGND and the adjustable end of the 20C R30 adjustable resistor, and the other end of the secondary is connected to the network INDUCED_CURRENT and the non-adjustable end of the R30 adjustable resistor;

[0023] The effective value calculation circuit adopts AD637 chip.

[0024] Furthermore, the sensor signal amplification circuit utilizes an operational amplifier AD623;

[0025] The voltage inversion circuit uses a CMOS voltage inverter ICL7660 to generate the -5V operating voltage required by AD623;

[0026] The working circuit of the temperature and humidity sensor adopts the peripheral circuit of the capacitive temperature and humidity sensor AM2305.

[0027] Furthermore, the USB to serial port circuit: the communication between the host computer and the single-chip microcomputer adopts serial port communication, and uses the chip CH340C with a built-in crystal oscillator inside the USB to serial port.

[0028] Furthermore, the OLED circuit: uses an OLED display to display relevant parameters and system internal operation information in real time through the OLED;

[0029] The data storage circuit is a peripheral circuit using W25Q128.

[0030] Beneficial effects: Compared with the prior art, the present invention has the following significant features: 1. By optimizing the signal processing circuit, such as using the low-noise, low-distortion AD797 operational amplifier to amplify the sine wave signal, and cooperating with the TLV3501 and other chips for subsequent signal conversion processing, the weak sweat signal can be accurately amplified and processed; 2. The high-speed optical coupler 6N137 is used to separate the analog circuit and the digital circuit, reducing the impact of analog interference on the digital circuit; the RCD absorption circuit is used in the full-bridge inverter circuit and other parts to suppress the voltage spike generated when the MOS tube is turned off, reducing the impact of external electromagnetic interference on the sensor signal acquisition and processing. 3. The system integrates multi-parameter monitoring functions. The temperature and humidity sensor working circuit can monitor the ambient temperature and humidity in real time, and cooperate with the monitoring of the sweat sensor to realize multi-parameter synchronous monitoring. The drive signal generation and amplification module can generate a sinusoidal signal with a frequency range of 0-12.5MHz and a minimum frequency step of 0.1Hz, and the full-bridge inverter circuit can achieve high-power adjustable output, which is suitable for different sensors and transducers. The data storage circuit uses 128Mb FLASH, which has the ability to work offline and store sensor data. The power management module can provide stable power supply. The overall function is rich and the application scenarios are wide. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 It is a schematic diagram of the system structure of the present invention;

[0032] Figure 2 is a system power supply circuit diagram of the present invention;

[0033] Figure 3 is a circuit diagram of a sine wave generator according to the present invention;

[0034] Figure 4 This is a circuit diagram of a sine wave signal amplification circuit of the present invention;

[0035] Figure 5 This is a circuit diagram of a sine wave to square wave converter according to the present invention;

[0036] Figure 6 It is a frequency division phase shift circuit diagram of the present invention;

[0037] Figure 7 It is a high-speed optocoupler circuit diagram of the present invention;

[0038] Figure 8 This is a full-bridge inverter circuit diagram of the present invention;

[0039] Figure 9 is a current mutual induction circuit diagram of the present invention;

[0040] Figure 10 It is a circuit diagram for calculating effective value of the present invention;

[0041] Figure 11 It is a sensor signal amplification circuit diagram of the present invention;

[0042] Figure 12 It is a voltage inversion circuit diagram of the present invention;

[0043] Figure 13 It is the working circuit diagram of the temperature and humidity sensor of the present invention;

[0044] Figure 14 This is the USB to serial port circuit diagram of the present invention;

[0045] Figure 15 It is the STM32 peripheral circuit diagram of the present invention;

[0046] Figure 16 is an OLED circuit diagram of the present invention;

[0047] Figure 17 It is a data storage circuit diagram of the present invention. DETAILED DESCRIPTION

[0048] The specific technical solutions of the present invention are further described in detail below with reference to specific examples.

[0049] As shown in the figure, the sweat sensing integrated circuit system based on ultrasonic drive and signal processing described in the present invention includes a power management module: its main circuit topology and control circuit work together to stably convert 220V AC into a DC power supply suitable for system operation, reducing the impact of input voltage fluctuations, improving power supply stability, and reducing device power consumption and operating costs.

[0050] Drive signal generation and amplification module: Adopts AD9833 chip and other devices to accurately generate and amplify the drive signal. Through a series of circuit processing, it meets the driving requirements of different transducers, ensures the stability of the ultrasonic field, and provides reliable excitation for sweat detection.

[0051] Sensor signal processing module: uses high-performance operational amplifiers to amplify and process sweat sensor signals, and combines temperature and humidity sensors to monitor environmental factors in real time, improving detection accuracy and reliability;

[0052] Control and communication module, display and storage module, etc.

[0053] The power management module includes a main circuit half-bridge topology and a control circuit. The main circuit half-bridge topology includes a DC input voltage, an inverter stage and an RCD absorption circuit. The control circuit includes: a PWM controller, a drive circuit and a feedback network.

[0054] The drive signal generation and amplification module includes a sine wave generation circuit, a sine wave signal amplification circuit, a sine wave to square wave circuit, a frequency division phase shift circuit, a high-speed optocoupler circuit, a full-bridge inverter circuit, a current mutual induction circuit, and an effective value calculation circuit;

[0055] The sensor signal processing module includes: a sensor signal amplification circuit, a voltage inversion circuit, and a temperature and humidity sensor working circuit;

[0056] The control and communication module includes: a USB to serial port circuit and an STM32 peripheral circuit;

[0057] The display and storage module includes an OLED circuit and a data storage circuit.

[0058] In the main circuit topology of the power management module, the DC input voltage is 220V AC. After passing through the EMI filter, bridge rectifier, and filter capacitor, the 220V AC is converted to 310V DC and then divided by resistors into 155V DC. The inverter stage is two switching tubes connected in series, with the midpoint connected to the primary end of the high-frequency transformer. The secondary of the transformer adopts full-wave rectification and LC filtering. The RCD absorption circuit is connected in parallel at both ends of Q4 / Q5 to absorb leakage inductance energy.

[0059] The drive signal generation and amplification module uses the chip AD9833 to generate a sinusoidal signal of the required frequency. When a 25MHz system clock is used, the frequency range of the AD9833 output signal is 0-12.5MHz, and the minimum frequency step is 0.1Hz, which can meet the requirements of transducer drive control.

[0060] Pin 1 of the AD9833 peripheral circuit is connected to one end of the 0.1uF / 50V C10 and C13 capacitors connected in series, pin 2 is connected to the middle of the C10 and C13 capacitors in series, pin 3 is connected to one end of the 10uF / 16V C11 capacitor and the 0.1uF / 50V C12 capacitor in parallel, the other end of the C11 and C12 parallel connection is connected to the other end of the C10 and C13 capacitors in series, pin 4 is connected to DGND, pin 5 is connected to pin 3 of the 25MHz system clock, pin 6 is connected to the 51Ω R12 resistor, and the other end of the R12 resistor is connected to the network TOMCU. _PB5, pin 7 is connected to the 51Ω resistor R11, the other end of the R11 resistor is connected to the network TOMCU_PB6, pin 8 is connected to the 51Ω resistor R10, the other end of the R10 resistor is connected to the network TOMCU_PB7, pin 9 is connected to DGND, pin 10 is connected to the 51Ω resistor R9, the other end of the R9 resistor is connected to the network SIN_WAVE_1, one end of the 100pF / 50V capacitor C14 is connected to pin 10 and the other end is connected to DGND, one end of the 100pF / 50V capacitor C15 is connected to the network SIN_WAVE_1 and the other end is connected to DGND;

[0061] The peripheral circuit of the 25MHz system clock, pin 1 is connected to one end of the 0.1uF / 50V C9 capacitor, the other end of the C9 capacitor is connected to DGND, pin 1 is connected to pin 4, pin 2 is connected to DGND, pin 4 is connected to one end of the 10uH L1 inductor, and the other end of the L1 inductor is connected to the VCC_5 power supply.

[0062] The sine wave generation circuit uses DDS technology, sets the frequency control word (M) through the SPI interface, reads 4096 pre-stored sine wave sampling points from the internal ROM lookup table to generate the waveform, and then converts it into an analog voltage through a 10-bit DAC. The theoretical maximum frequency is 12.5MHz. If high-frequency distortion occurs, an external low-pass filter can be used.

[0063] The sine wave signal amplifier circuit described above is not easy to perform voltage comparison because the amplitude of the sine wave signal generated by the AD9833 is only about 100mV. Therefore, the sine signal needs to be amplified. This system uses the AD797 op amp for signal amplification. The op amp has the characteristics of low noise and low distortion and is suitable for use as a preamplifier. The amplification factor of the op amp is changed by adjusting the adjustable resistor R15 located between the output pin 6 and the negative input pin 2. In the system design, the amplitude of the signal input to the AD9833 is amplified to 3V.

[0064] Pin 2 of the AD797 peripheral circuit is connected to one end of the 1KΩ R13 and 100KΩ R15 adjustable resistors, the other end of the R13 resistor is connected to DGND, pin 3 is connected to the network SIN_WAVE_1, one end of the 1KΩ R14 resistor is connected to pin 3 and the other end is connected to DGND, pin 4 is connected to the power supply VCC_-5, a 0.1uF C16 capacitor is connected in parallel with a 100uF C17 capacitor, one end of C16 and C17 in parallel is connected to pin 4 and the other end is connected to DGND, pin 6 is connected to the network SIN_WAVE, the other end of the R15 adjustable resistor is connected to pin 6 of the middle adjustment terminal, pin 7 is connected to the power supply 5V, a 0.1uF C18 capacitor is connected in parallel with a 100uF C19 capacitor, one end of C18 and C19 in parallel is connected to pin 4 and the other end is connected to DGND.

[0065] To obtain a square wave signal to drive the full-bridge MOS transistor, the sine wave to square wave circuit uses a voltage comparator TLV3501 to convert the sine wave amplified by the AD797 op amp into a square wave. The TLV3501 is a rail-to-rail high-speed comparator with a delay of only 4.5ns, which can adjust the input signal to a TTL logic signal output. By adjusting the adjustable resistor R16 to change the comparison voltage threshold, the duty cycle of the output square wave signal can be adjusted.

[0066] Pin 2 of the TLV3501 peripheral circuit is connected to one end of a 0.1uF C20 capacitor and a 10KΩ R16 adjustable resistor in parallel, the R16 adjustable terminal is connected to pin 2, the other end of C20 and R16 in parallel is connected to DGND, one end of the 10KΩ R17 resistor is connected to pin 2 and the other end is connected to pin 7, pin 3 is connected to the network SIN_WAVE, pin 4 is connected to DGND, pin 6 is connected to the network SQU_WAVE_1, pin 7 is connected to the VCC_5 power supply, one end of a 10uF C21 capacitor and a 0.1uF C22 capacitor in parallel is connected to pin 7 and the other end is connected to DGND, and pin 8 is connected to DGND.

[0067] The frequency division phase shift circuit driving signal needs to be a complementary square wave signal with a dead zone. The frequency division phase shift circuit composed of an inverter SN74LS14N, a JK flip-flop CD4027, and a 3-input NAND gate SN74HC11N is applied to the output signal of TLV3501 to divide the square wave signal output by the voltage comparator TLV3501 by two to obtain a center-aligned complementary square wave signal; Pin 1 of the peripheral circuit of the SN74LS14N is connected to the network SQU_WAVE_1, Pin 2 is connected to Pin 13, Pin 7 is connected to DGND, Pin 12 is connected to Pin 2 of the SN74HC11N, and Pin 14 is connected to the VCC_5 power supply; Pin 8 of the CD4027's peripheral circuit is connected to DGND, pin 9 is connected to pin 8, pin 10 is connected to pin 11, pin 11 is connected to pin 16, pin 12 is connected to pin 9, pin 13 is connected to pin 2 of SN74LS14N, pin 14 is connected to pin 3 of SN74HC11N, pin 15 is connected to pin 1 of SN74HC11N, and pin 16 is connected to a 5V power supply; pin 4 of the SN74HC11N's peripheral circuit is connected to pin 2, pin 5 is connected to pin 13, pin 6 is connected to network PWM_2, pin 7 is connected to DGND, pin 12 is connected to network PWM_1, pin 13 is connected to VCC_5 power supply, and pin 14 is connected to pin 13.

[0068] The high-speed optocoupler circuit uses a high-speed optocoupler 6N137 to separate the analog circuit and the digital circuit to reduce the impact of analog interference on digital circuits such as microcontrollers, operational amplifiers, and comparators; the peripheral circuit pins 2 of the two 6N137 are connected to the VCC_5 power supply, pin 3 is connected to one end of the 20Ω R18 / R19 resistor, the other end of R18 / R19 is connected to the network PWM_1 / PWM_2, pin 5 is connected to AGND, 0.1uF C23 / C24 is connected to pin 5 and the other end is connected to the power supply VCC_5A, pin 6 is connected to the network PWM1, one end of the 100Ω R20 / R21 resistor is connected to pin 6 and the other end is connected to pin 8, and pin 8 is connected to the power supply VCC_5A; the high-speed optocoupler 6N137 outputs complementary square wave signals PWM1 and PWM2 with the analog ground AGND as the reference ground, and the frequency, dead zone and duty cycle are consistent with the driving signal input from the front end; the signal is input to the high and low edge driver IR2110S to improve the signal driving MOS tube Capacity, the VS pins of the two IR2110S are respectively connected to the midpoints of the left and right bridge arms of the full-bridge circuit and connected to the load. Through the bootstrap circuit, the voltage output by pin 8 is referenced to the voltage of pin 7, and the voltage output by pin 1 is referenced to the analog ground AGND; network HO1 and network LO2 are square wave signals with the same frequency and phase, and HO2 and LO1 are square wave signals with the same frequency and phase; when HO1 is high relative to VS1 and LO2 is high relative to AGND, MOS tubes Q1 and Q4 are turned on. At this time, HO2 is low relative to VS2 and LO1 is low relative to AGND, MOS tubes Q2 and Q3 are turned off, and the voltage loaded across the load is VS1 is + and VS2 is -. Conversely, when Q1 and Q4 are turned off and Q2 and Q3 are turned on, the voltage loaded across the load is VS1 is - and VS2 is +. In order to suppress the voltage spike generated when the MOS tube is turned off, an RCD absorption circuit is used in the design to reduce the impact of the voltage spike on the circuit.

[0069] Pin 1 of the peripheral circuit of the two IR2110S is connected to the network LO1 / LO2, pin 2 is connected to AGND, pin 3 is connected to the VCC_12A power supply, the anode of the D1 / D2 diode of the 1N5819 is connected to pin 3, the cathode is connected to pin 7, pin 6 is connected to the network VS1 / VS2, one end of the 10uF C25 / C31 capacitor is connected to pin 6 and the other end is connected to pin 7; pin 8 is connected to the network HO1 / HO2, pin 11 is connected to the VCC_5A power supply, one end of the 0.1uF C26 / C32 capacitor is connected to pin 11 and the other end is connected to AGND, pin 12 is connected to the network PWM2, pin 14 is connected to the network PWM1, and pin 15 is connected to AGND.

[0070] An RCD absorption circuit is connected in parallel between the source and drain of the four N-channel MOS tubes Q1 / Q2 / Q3 / Q4 in the full-bridge inverter circuit; the cathode of the ES3JB fast recovery diode D3 / D5 / D4 / D6 in the RCD absorption circuit is connected to the drain of the MOS tube Q1 / Q2 / Q3 / Q4, the anode of D3 / D5 / D4 / D6 is connected to one end of the 100nF C35 / C36 / C39 / C40 connected in parallel with the 220Ω R24 / R25 / R28 / R29 resistor, and the other end of the capacitor and resistor in parallel is connected to Q1 / MOS transistor source stage of Q2 / Q3 / Q4; the gates of the four N-channel MOS transistors Q1 / Q2 / Q3 / Q4 are connected to one end of the 1nF capacitor C33 / C34 / C37 / C38, and the other end of the capacitor is connected to AGND; one end of the 4Ω resistor R22 / R23 / R26 / R27 is connected to the MOS transistor gates of Q1 / Q2 / Q3 / Q4, and the other end of the resistor is connected to the network HO1 / LO1 / HO2 / LO2; the drains of Q1 and Q3 are connected to the network OUT+, and the drains of Q2 and Q4 are connected to the network GND_OUT-.

[0071] The current transformer circuit uses electrical feedback. Under the same input voltage conditions, the frequency is fine-tuned to maintain current consistency, ensuring the stable distribution of the ultrasonic field of the sweat sensor. The primary of the peripheral circuit of the current transformer is connected to the networks VS1 and VS2, one end of the secondary is connected to DGND and the adjustable end of the 20C adjustable resistor R30, and the other end of the secondary is connected to the network INDUCED_CURRENT and the non-adjustable end of the adjustable resistor R30.

[0072] In order to reduce the A / D sampling time of the single-chip microcomputer and reduce the computational burden of the single-chip microcomputer in calculating the effective value of the sine wave, the circuit for calculating the effective value of the effective value adopts the AD637 chip in the system design; the peripheral circuit pin 1 of the AD637 is connected to one end of the 22uF / 25V C41 capacitor, the other end of the C41 capacitor is connected to DGND, one end of the 47KΩ R34 resistor is connected to pin 1 and the other end is connected to one end of the 22uF / 25V C42 capacitor, the other end of the C42 capacitor is connected to pin 16, the 47KΩ R35 resistor is connected between the R34 resistor and the C42 capacitor, and the other end is connected to pin 11, pin 3 is connected to DGND, the 0.1uF / 50V C95 capacitor is connected to pin 3, the other end of the C95 capacitor is connected to pin 12, pin 4 is connected to one end of the 1MΩ R32 resistor, the other end of the R32 resistor is connected to the adjustable end of the 100KΩ R31 adjustable resistor, and the two non-adjustable ends of the R31 adjustable resistor are respectively connected to the VCC_-5 power supply and VCC_5 power supply, pin 5 is connected to one end of the 5.1KΩ R33 resistor, the other end of the R33 resistor is connected to the VCC_5 power supply, pin 6 is connected to pin 11, pin 10 is connected to one end of the 22uF / 25V C45 capacitor, the other end is connected to pin 11, pin 11 is connected to one end of the 51Ω R38 resistor, the other end of the R38 resistor is connected to the network TOMCU_PA2, pin 12 is connected to the VCC_-5 power supply, pin 13 is connected to the VCC_5 power supply, one end of the 0.1uF / 50V C43 capacitor is connected to pin 13 and the other end is connected to DGND, pin 15 is connected to one end of the 22uF / 25V C44 capacitor, the other end of the C44 capacitor is connected to the INDUCED_CURRENT network, one end of the 1MΩ R36 resistor is connected to the INDUCED_CURRENT network and the other end is connected to pin 3, pin 16 is connected to one end of the 51Ω R37 resistor, the other end of the R37 resistor is connected to pin 1 of P4, and pin 2 of P4 is connected to DGND.

[0073] The sensor signal amplification circuit utilizes the operational amplifier AD623; the peripheral circuit of the AD623 comprises an 11KΩ resistor R6 between pins 1 and 8, a 1KΩ resistor R1 connected to pin 2, the other end of the resistor R1 connected to the negative electrode of the sweat sensor output, a 1KΩ resistor R4 connected to pin 3, the other end of the resistor R4 connected to the positive electrode of the sweat sensor output, a middle adjustment end of the adjustable resistor R3 connected between the positive electrode of the sweat sensor output and the middle of the resistor R4, the left and right ends of the resistor R3 connected to 10KΩ resistors R2 and R5 respectively, the other ends of the resistors R2 and R5 connected to 5V and -5V power supplies respectively, pin 4 connected to the VCC_-5 power supply, one end of a 0.1uF capacitor C1 connected to pin 4 and the other end connected to GND, pin 5 connected to GND, pin 6 connected to the network CAS_SENSOR / PA1, pin 7 connected to the VCC_5 power supply, and one end of a 0.1uF capacitor C2 connected to pin 7 and the other end connected to GND; the AD623 is powered by a ±5V dual power supply.

[0074] The voltage inversion circuit uses a CMOS voltage inverter ICL7660 to generate the -5V operating voltage required by AD623; the peripheral circuit of the ICL7660, pin 2 is connected to the positive electrode of the 22uF / 25V C3 capacitor, the negative electrode of the C3 capacitor is connected to pin 4, pin 3 is connected to GND, pin 5 is connected to the VCC_-5 power supply, the negative electrode of the 220uF / 16V C4 capacitor and one end of the 0.1uF C5 capacitor are connected to pin 5, the positive electrode of the C4 capacitor and the other end of the C5 capacitor are connected to GND, pin 6 is connected to the 0.1uF C7 capacitor, the other end of the C7 capacitor is connected to GND, pin 8 is connected to the VCC_5 power supply, and one end of the 0.1uF C6 capacitor is connected to pin 8 and the other end is connected to GND.

[0075] The working circuit of the temperature and humidity sensor adopts the peripheral circuit of the capacitive temperature and humidity sensor AM2305. Pin 1 is connected to the VCC_5 power supply, one end of the 10uF C96 capacitor is connected to pin 1 and the other end is connected to DGND, one end of the 1KΩ R7 resistor is connected to pin 1 and the other end is connected to the network TOMCU_PB10, pin 2 is connected to the 200Ω R8 resistor, the other end of the R8 resistor is connected to the network TOMCU_PB10, one end of the 1nF C8 capacitor is connected to pin 2 and the other end is connected to DGND, and pin 3 is connected to DGND.

[0076] The communication between the host computer and the single-chip microcomputer of the USB-to-serial port circuit adopts serial port communication, and uses the USB-to-serial port chip CH340C. The CH340C has its own crystal oscillator, which makes the PCB layout more compact; Pin 1 of the peripheral circuit of the CH340C is connected to DGND, Pin 2 is connected to one end of the 1KΩ R47 resistor, and the other end of the R47 resistor is connected to the network PA10 / RXD, Pin 3 is connected to one end of the 1KΩ R48 resistor, and the other end of the R48 resistor is connected to the network PA9 / TXD, Pin 4 is connected to one end of the 0.1uF C71 capacitor, and the other end of the C71 capacitor is connected to DGND, Pin 5 is connected to the network USB_D+, Pin 6 is connected to the network USB_D-, Pin 16 is connected to the VCC_5 power supply, and one end of the 0.1uF C72 capacitor and the 10uF C73 capacitor connected in parallel is connected to the VCC_5 power supply and the other end is connected to DGND;

[0077] The peripheral circuit pin 1 of the USB1 is connected to the VCC_5 power supply, pin 2 is connected to the network USB_D-, pin 3 is connected to the network USB_D+, pin 4 is connected to DGND, pin 5 is connected to DGND, and pin 6 is connected to DGND.

[0078] Pin 1 of the STM32F446RET6 peripheral circuit is connected to the VCC_3.3 power supply, pin 3 is connected to the network OSC_IN1, pin 4 is connected to the network OSC_OUT1, pin 5 is connected to the network OSC_IN2, pin 6 is connected to the network OSC_OUT2, pin 7 is connected to the network RESET, pin 12 is connected to DGND, one end of the 0.1uF C59 capacitor is connected to pin 12 and the other end is connected to the VCC_3.3 power supply, pin 13 is connected to one end of the 10uF L3 inductor, the other end of the L3 inductor is connected to the VCC_3.3 power supply, pin 14 is connected to the network WK_UP, and pin 15 is connected to the network CA S_SENSOR / PA1, pin 16 is connected to the network TOMCU_PA2, pin 18 is connected to DGND, one end of the 0.1uF C60 capacitor is connected to pin 18 and the other end is connected to pin 19, pin 19 is connected to the VCC_3.3 power supply, pin 20 is connected to the network FLASH / SPI1_NSS, pin 21 is connected to the network FLASH / SPI1_SCK, pin 22 is connected to the network FLASH / SPI1_MISO, pin 23 is connected to the network FLASH / SPI1_MOSI, pin 27 is connected to the VCC12_CTR1 power supply, and pin 28 is connected to the 10KΩ R43 resistor One end, the other end of R43 is connected to DGND, pin 29 is connected to the network TOMCU_PB10, pin 30 is connected to one end of the 4.7uF C61 capacitor, the other end of C61 is connected to DGND, pin 31 is connected to DGND, one end of the 0.1uF C62 capacitor is connected to pin 31 and the other end is connected to pin 32, pin 32 is connected to VCC_3.3 power supply, pin 40 is connected to the network OLED_SDA / PC9, pin 41 is connected to the network OLED_SCL / PA8, pin 42 is connected to the network PA9 / TXD, pin 43 is connected to the network PA10 / RXD, and pin 46 is connected to the network SWDIO / PA 13. Connect pin 47 to DGND, connect one end of the 0.1uF capacitor C64 to pin 47 and the other end to pin 48, connect pin 48 to the VCC_3.3 power supply, connect pin 49 to the network SWCLK / PA14, connect pin 57 to the network TOMCU_PB5, connect pin 58 to the network TOMCU_PB6, connect pin 59 to the network TOMCU_PB7, connect pin 60 to one end of the 10KΩ resistor R44, and connect the other end of R44 to DGND, connect pin 63 to DGND, connect pin 64 to the VCC_3.3 power supply, connect one end of the 0.1uF capacitor to pin 64 and the other end to DGND;

[0079] One end of the K1 button is connected to the network RESET and the other end is connected to DGND. One end of the 10KΩ R45 resistor is connected to the network RESET and the other end is connected to the VCC_3.3 power supply. One end of the 0.1uF C65 capacitor is connected to the network RESET and the other end is connected to DGND. One end of the K2 button is connected to the VCC_3.3 power supply and the other end is connected to the network WK_UP. One end of the Y1 crystal oscillator is connected to the network OSC_IN2 and the other end is connected to the network OSC_OUT2. One end of the 1MΩ R46 resistor is connected to the network OSC_IN2. The other end is connected to the network OSC_OUT2, one end of the 20pF capacitor C66 is connected to the network OSC_IN2 and the other end is connected to DGND, one end of the 20pF capacitor C67 is connected to the network OSC_OUT2 and the other end is connected to DGND; one end of the Y2 crystal oscillator is connected to the network OSC_IN1 and the other end is connected to the network OSC_OUT1, one end of the 12pF capacitor C69 is connected to the network OSC_IN1 and the other end is connected to DGND, one end of the 12pF capacitor C70 is connected to the network OSC_OUT1 and the other end is connected to DGND.

[0080] In order to facilitate users to monitor the ambient temperature and humidity and the driving voltage and current of the piezoelectric transducer, the OLED circuit uses an OLED display in the system design to display relevant parameters and internal system operation information in real time through the OLED;

[0081] The peripheral circuit pin 1 of the OLED is connected to DGND, pin 2 is connected to the VCC_5 power supply, pin 3 is connected to the network OLED_SCL / PA8, and pin 4 is connected to the network OLED_SDA / PC9.

[0082] In order to enable the system to work offline and store sensor data, a 128Mb FLASH is used in the system hardware design to store relevant parameters of the system during power failure.

[0083] Pin 1 of the W25Q128 peripheral circuit is connected to the network FLASH / SPI1_NSS, one end of the 4.7KΩ R49 resistor is connected to pin 1 and the other end is connected to pin 7, pin 2 is connected to the network FLASH / SPI1_MISO, pin 3 is connected to pin 7, pin 4 is connected to DGND, pin 5 is connected to the network FLASH / SPI1_MOSI, pin 6 is connected to the network FLASH / SPI1_SCK, pin 7 is connected to pin 8, pin 8 is connected to the VCC_3.3 power supply, and one end of the 0.1uF C74 capacitor is connected to pin 8 and the other end is connected to DGND.

[0084] In practical applications, such as when wearable medical devices monitor human sweat, the various modules of the system cooperate with each other; the power management module provides stable power, the drive signal generation and amplification module stimulates the sweat sensor to work, the sensor signal processing module processes the collected sweat and environmental signals, the control and communication module realizes data transmission and system control, and the display and storage module displays and saves data; the present invention optimizes the design of each module to achieve high-precision, low-noise, and anti-interference sweat detection, supports multi-parameter monitoring and high-power adjustable output, solves the problems existing in existing sweat sensor integrated circuit systems, and promotes the development of wearable medical devices and health monitoring fields.

Claims

1. A sweat sensing integrated circuit system based on ultrasonic driving and signal processing, characterized in that: It includes power management module, drive signal generation and amplification module, sensor signal processing module, control and communication module, display and storage module; The power management module includes a main circuit half-bridge topology and a control circuit; The drive signal generation and amplification module includes a sine wave generation circuit, a sine wave signal amplification circuit, a sine wave to square wave circuit, a frequency division phase shift circuit, a high-speed optocoupler circuit, a full-bridge inverter circuit, a current mutual induction circuit and an effective value calculation circuit; The sensor signal processing module includes a sensor signal amplification circuit, a voltage inversion circuit and a temperature and humidity sensor working circuit; The control and communication module includes a USB to serial port circuit and an STM32 peripheral circuit; The display and storage module includes an OLED circuit and a data storage circuit.

2. The sweat sensing integrated circuit system based on ultrasonic driving and signal processing according to claim 1, characterized in that: The main circuit half-bridge topology includes a DC input voltage, an inverter stage and an RCD absorption circuit; The control circuit includes a PWM controller, a driving circuit and a feedback network.

3. The sweat sensing integrated circuit system based on ultrasonic driving and signal processing according to claim 2, characterized in that: The DC input voltage in the half-bridge topology of the main circuit is converted from 220V AC to 310V DC after passing through an EMI filter, a bridge rectifier, and a filter capacitor, and then divided by resistors to 155V DC; The inverter stage is two switching tubes connected in series, with the midpoint connected to the primary end of the high-frequency transformer. The secondary of the transformer adopts full-wave rectification and LC filtering. The RCD absorption circuit is connected in parallel across Q4 / Q5 to absorb leakage inductance energy.

4. The sweat sensing integrated circuit system based on ultrasonic driving and signal processing according to claim 1, characterized in that: The drive signal generation and amplification module uses the chip AD9833 to generate a sinusoidal signal of the required frequency; when a 25MHz system clock is used, the frequency range of the AD9833 output signal is 0-12.5MHz, and the minimum frequency step is 0.1Hz.

5. The sweat sensing integrated circuit system based on ultrasonic driving and signal processing according to claim 1, characterized in that: The sine wave generating circuit sets the frequency control word through the SPI interface, reads 4096 pre-stored sine wave sampling points from the internal ROM lookup table to generate the waveform, and converts it into an analog voltage through a 10-bit DAC; The sine wave signal amplification circuit uses an AD797 operational amplifier to amplify the signal, and the amplification factor of the operational amplifier is changed by adjusting the adjustable resistor R15 located between the output terminal pin 6 and the negative input terminal pin 2; The sine wave to square wave circuit uses the voltage comparator TLV3501 to convert the sine wave amplified by the operational amplifier AD797 into a square wave; by adjusting the adjustable resistor R16, the threshold value of the comparison voltage is changed to adjust the duty cycle of the output square wave signal; The frequency division phase shift circuit applies a frequency division phase shift circuit composed of an inverter SN74LS14N, a JK flip-flop CD4027 and a 3-input NAND gate SN74HC11N to the output signal of the TLV3501 to divide the square wave signal output by the voltage comparator TLV3501 by two, thereby obtaining a center-aligned complementary square wave signal; The high-speed optocoupler circuit uses the high-speed optocoupler 6N137 to separate the analog circuit from the digital circuit; An RCD absorption circuit is connected in parallel between the source and drain of the four N-channel MOS tubes Q1 / Q2 / Q3 / Q4 of the full-bridge inverter circuit; The current mutual inductance circuit adopts electric feedback, and the primary of its peripheral circuit is connected to the networks VS1 and VS2, one end of the secondary is connected to DGND and the adjustable end of the 20C R30 adjustable resistor, and the other end of the secondary is connected to the network INDUCED_CURRENT and the non-adjustable end of the R30 adjustable resistor; The effective value calculation circuit adopts AD637 chip.

6. The sweat sensing integrated circuit system based on ultrasonic driving and signal processing according to claim 1, characterized in that: The sensor signal amplification circuit uses an operational amplifier AD623, and its peripheral circuit is connected to a resistor and a capacitor to amplify the signal of the sweat sensor; The voltage inversion circuit uses the CMOS voltage inverter ICL7660 to generate the -5V operating voltage required by AD623; The working circuit of the temperature and humidity sensor uses the peripheral circuit of the capacitive temperature and humidity sensor AM2305.

7. The sweat sensing integrated circuit system based on ultrasonic driving and signal processing according to claim 1, characterized in that: The USB to serial port circuit: The communication between the host computer and the single-chip microcomputer adopts the serial port communication method, using the chip CH340C with a built-in crystal oscillator inside the USB to serial port; The STM32 serves as a core control unit, and its peripheral circuits are connected to a crystal oscillator, a reset circuit, and a button.

8. The sweat sensing integrated circuit system based on ultrasonic driving and signal processing according to claim 1, characterized in that: The OLED circuit uses an OLED display to display parameters and internal operating information of the system in real time through the OLED; The data storage circuit uses a 128Mb FLASH chip.

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