Continuous blood glucose monitoring circuit

Abstract

The invention relates to a continuous blood glucose monitoring circuit, which takes a 32-bit ARM (Advanced RISC Machines) processor of an STM32F407 singlechip as a main controller and an ADS131A04 high-precision synchronous sampling ADC (Analog to Digital Converter) chip as a core, comprises a main control circuit, a signal acquisition circuit, a constant potential circuit, a constant current circuit and a power supply circuit, is connected with a blood glucose sensor by adopting an FPC (Flexible Printed Circuit) connector, and is used for continuously monitoring blood glucose under the condition of constant current stimulation and constant voltage. The output signal of the sensor is collected in real time, and after the main control processes the data, the collected data is stored in the MicroSD card and is displayed on the screen at the same time. Intelligent control over the continuous blood glucose monitoring system is achieved by means of the high running speed and rich interface resources of the STM32F407; the multi-channel design can monitor relevant ion concentration parameters while collecting blood glucose signals, and can accurately monitor the blood glucose and the relevant ion concentration of a human body and correct the blood glucose signals in cooperation with a blood glucose sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of biosensing signal monitoring, and particularly relates to a continuous glucose monitoring circuit. BACKGROUND

[0002] Diabetes is a chronic metabolic disease. According to research published in The Lancet in 2023, although the understanding of diabetes has increased, and many countries around the world are making efforts, diabetes is still prevalent and the prevalence rate is increasing dramatically, more than most other diseases, and it is estimated that there will be 1.3 billion people suffering from diabetes by 2050. Diabetes not only has a serious impact on the quality of life of patients, but also increases the risk of complications such as cardiovascular disease, kidney disease, and retinopathy. Therefore, effective blood glucose monitoring and management are crucial for preventing and controlling diabetes and its complications.

[0003] Traditional blood glucose monitoring methods mainly rely on finger prick blood sampling. Although this method is accurate, it has problems such as pain and discomfort, infection risk, inconvenience of operation, and inability to monitor continuously. Specifically:

[0004] Pain and discomfort: Frequent finger prick blood sampling can cause pain and discomfort to patients, especially for patients who need to be monitored multiple times.

[0005] Infection risk: There is a risk of infection during blood sampling, especially when operating in unclean environments.

[0006] Inconvenience of operation: Traditional blood glucose monitoring requires patients to operate themselves, which is inconvenient for elderly patients or patients with poor vision.

[0007] Inability to monitor continuously: Traditional blood glucose monitoring methods can only provide single-point data and cannot achieve continuous and real-time blood glucose monitoring, making it difficult to fully reflect the blood glucose fluctuation of patients.

[0008] In order to overcome the limitations of traditional blood glucose monitoring methods, non-invasive blood glucose monitoring technology has emerged, aiming to solve the limitations of traditional methods and provide more comfortable and convenient monitoring means for diabetic patients. Non-invasive blood glucose monitoring technology uses non-invasive means to indirectly measure blood glucose concentration through principles such as optics, electrochemistry, and electromagnetic waves. In recent years, with the progress of sensor technology, signal processing technology, and artificial intelligence algorithms, non-invasive blood glucose monitoring technology has made significant progress.

[0009] Wearable continuous glucose monitoring (CGM) products have garnered widespread attention due to their portability and ability to monitor patients' blood glucose levels over long periods. Currently, mature CGM products on the market primarily utilize electrochemical principles, such as those from Abbott, Medtronic, silicon-based companies, and Sinocare. However, most require patients to implant sensor electrodes under the skin using an auxiliary device to monitor the blood glucose concentration in the interstitial fluid. These implantable sensors still cause pain and may lead to inflammation and infection, failing to meet safety and health requirements and significantly reducing user compliance. Furthermore, these devices often suffer from low accuracy, unstable measurements, and signal drift. With the continuous development of reverse iontophoresis blood glucose sensors, which can be directly attached to the skin surface for non-invasive, continuous, and long-term blood glucose monitoring, a circuit with multi-channel weak signal acquisition capabilities is urgently needed to adapt to such reverse iontophoresis blood glucose sensors (e.g., CN119846039A). Summary of the Invention

[0010] The technical problem to be solved by the present invention is to provide a continuous blood glucose monitoring circuit.

[0011] To solve the above-mentioned technical problems, the technical solution proposed by the present invention is as follows:

[0012] A continuous blood glucose monitoring circuit includes a main control circuit, a signal acquisition circuit, a constant potential circuit, a constant current circuit, and a power supply circuit. The main control circuit is connected to the signal acquisition circuit, the constant potential circuit, and the constant current circuit. The constant potential circuit is connected to the signal acquisition circuit. The power supply circuit is connected to the main control circuit, the signal acquisition circuit, the constant potential circuit, and the constant current circuit to supply power.

[0013] The main control circuit is based on the 32-bit microcontroller STM32F407VET6 microcontroller, which is used to realize general I / O port control, SPI communication, serial communication, II2C communication, and real-time operating system configuration.

[0014] The signal acquisition circuit uses a four-channel high-performance synchronous sampling ADC chip to convert analog signals into digital signals;

[0015] The constant potential circuit is used to provide a stable constant potential difference;

[0016] The constant current circuit is used to output a precise, weak current.

[0017] The power supply circuit is used to provide a continuous and stable power supply and to charge the lithium battery.

[0018] Preferably, in the above-mentioned continuous blood glucose monitoring circuit, the main control circuit includes a main chip circuit, a clock circuit, a reset circuit, a serial port circuit, a screen circuit, a storage circuit, and an STLINK debug interface circuit. The main chip circuit uses an STM32F407VET 632-bit microcontroller with ARM architecture. The Cortex-M4 core, with a main frequency of up to 168MHz, features high performance and low power consumption, providing strong computing power and facilitating multi-channel signal acquisition and processing. The clock circuit is connected to pins 12 and 13 of the main chip circuit, the reset circuit is connected to pin 14 of the main chip circuit, the serial port circuit is connected to pins 68 and 69 of the main chip circuit, the screen circuit is connected to pins 30, 32, 47, 48, 53, 54, 63, 70, and 71 of the main chip circuit, the storage circuit is connected to pins 65, 66, 78-80, and 83 of the main chip circuit, and the STLINK debug interface circuit is connected to pins 72 and 76 of the main chip circuit. The main control circuit is used for inter-circuit communication, signal processing, control logic, and data management.

[0019] Preferably, in the above-mentioned continuous blood glucose monitoring circuit, the signal acquisition circuit is a multi-channel signal acquisition circuit, consisting of an ADS131A04 four-channel high-performance synchronous sampling ADC chip, a front-end processing circuit, and a clock circuit. Pin 2 of one ADS131A04 four-channel high-performance synchronous sampling ADC chip is connected to the front-end processing circuit, pin 8 of another ADS131A04 four-channel high-performance synchronous sampling ADC chip is connected to the front-end processing circuit, and pins 25 and 26 of the ADS131A04 four-channel high-performance synchronous sampling ADC chip are connected to the clock circuit. The ADS131A04 four-channel high-performance synchronous sampling ADC is used to sample the signal output by the blood glucose sensor in real time, converting the analog voltage signal into a digital signal so that the microcontroller can analyze and process the data in a timely manner.

[0020] Preferably, in the above-mentioned continuous blood glucose monitoring circuit, the signal acquisition circuit first performs front-end processing of the current signal. Because the ADC chip can only acquire analog voltage signals, the analog current signal needs to be converted into an analog voltage signal by the front-end processing circuit before entering the four-channel ADC chip. In the front-end processing circuit, the MAX4238 chip acts as a transimpedance amplifier. The OUT pins of the MAX4238 chips in the two front-end processing circuits are respectively connected to pins 2 and 8 of the two ADS131A04 four-channel high-performance synchronous sampling ADC chips to convert the analog current signal into an analog voltage signal.

[0021] Preferably, in the above-mentioned continuous blood glucose monitoring circuit, the constant potential circuit includes a DAC8531 low-power digital-to-analog converter chip, an RS8552 operational amplifier, and a REF3130 reference source. Pins 3 and 4 of the DAC8531 low-power digital-to-analog converter chip are connected to pin 5 of the RS8552 operational amplifier through a resistor. The OUT pin of the REF3130 reference source is connected to pin 3 of the RS8552 operational amplifier. At the same time, pin 1 of the RS8552 operational amplifier is connected to the positive input terminal of the MAX4238 chip in the signal acquisition circuit through a resistor to provide a stable potential difference.

[0022] Preferably, in the above-mentioned continuous blood glucose monitoring circuit, the constant current circuit includes a DAC8531 low-power digital-to-analog converter chip, an OP07 operational amplifier, an OPA2196 operational amplifier, and a relay. Pins 3 and 4 of the DAC8531 low-power digital-to-analog converter chip are connected to pin 3 of the OP07 operational amplifier. Pin 6 of the OP07 operational amplifier is connected to pins 3 and 7 of the OPA2196 operational amplifier through a resistor. Pins 1 and 5 of the OPA2196 operational amplifier are connected to the relay through a resistor, for outputting a precise weak current.

[0023] Preferably, in the above-mentioned continuous blood glucose monitoring circuit, the power supply circuit includes an IP2325 lithium battery charging chip, a TPS54231 buck chip, a TPS7A4701 linear regulator, an MT3608 boost converter, an AMS1117 linear regulator, a Type-C interface, and a battery interface. The Type-C interface is connected to the IP2325 lithium battery charging chip, and pin 2 of the IP2325 lithium battery charging chip is connected to the battery interface. The battery interface is connected via switches to the VIN pins of the two TPS54231 buck chips and pins 4 and 5 of the MT3608 boost converter, respectively. The two TPS54231 step-down chips are connected to pin 3 of the AMS1117 linear regulator and pins 13 and 15 of the two TPS7A4701 linear regulators, respectively. The IP2325 lithium battery charging chip is used to charge the 7.4V lithium battery. The MT3608 boost converter boosts the lithium battery voltage to 16V to provide a stable power supply for the constant current circuit. The TPS54231 step-down chip serves two purposes: first, it reduces the lithium battery voltage to 5V to power the constant current circuit; second, it is used in combination with the LDO chip to provide a low-noise, stable power supply for the signal acquisition circuit and the constant potential circuit. The TPS7A4701 linear regulator acts as a post-stage regulator for the TPS54231 step-down chip, powering the signal acquisition circuit and the constant potential circuit. The AMS1117 linear regulator further reduces the 5V output from the TPS54231 step-down chip to 3.3V, providing a stable power supply for the main control circuit, the constant potential circuit, and the signal acquisition circuit.

[0024] Preferably, the above-mentioned continuous blood glucose monitoring circuit includes two FPC connectors. One FPC connector is located in the main control circuit for connecting to the screen circuit, and the other FPC connector is located in the signal acquisition circuit, constant current circuit, and constant potential circuit. The FPC connector is connected to the blood glucose sensor. The blood glucose sensor is connected to pins 2, 4, and 6 of one ADC chip and pins 4, 6, and 8 of another ADC chip in the signal acquisition circuit, the inverting input terminals of two MAX4238 chips, pin 7 of two RS8552 operational amplifiers in the constant potential circuit, and pins 3 and 6 of the relay in the constant current circuit via the FPC connector.

[0025] The aforementioned continuous blood glucose monitoring circuit uses an FPC connector to connect to the blood glucose sensor (CN119846039A). Through constant current stimulation, under constant pressure conditions, the output signal of the sensor is acquired in real time. After processing and analysis, the data is stored in the MicroSD card in the storage circuit and simultaneously displayed on the screen of the screen circuit.

[0026] Technical effect

[0027] The aforementioned continuous blood glucose monitoring circuit uses a 32-bit ARM processor based on the STM32F407 microcontroller as the main controller and the ADS131A04 high-precision synchronous sampling ADC chip as its core. It includes a main control circuit, signal acquisition circuit, constant potential circuit, constant current circuit, and power supply circuit. It connects to the blood glucose sensor via an FPC connector. Through constant current stimulation, under constant voltage conditions, it acquires the sensor's output signal in real time. After processing the data, the main controller stores the acquired data on a MicroSD card and displays it on the screen. Utilizing the high operating speed and rich interface resources of the STM32F407, it achieves intelligent control of the continuous blood glucose monitoring system. The multi-channel design allows for monitoring of related ion concentration parameters while acquiring blood glucose signals. Combined with the blood glucose sensor, it enables accurate monitoring of blood glucose and related ion concentrations, and allows for correction of the blood glucose signal. Specifically:

[0028] 1. The main control circuit uses an STM32F407VET6 32-bit microcontroller with an ARM Cortex-M4 core and a main frequency of 168MHz, which has strong computing power. It has rich peripheral interfaces, such as USART, SPI, I2C, Ethernet, etc., which is conducive to realizing the functions of automated control, data acquisition and storage of continuous blood glucose monitoring.

[0029] 2. A high-performance synchronous sampling ADC chip is used to acquire signals from eight channels of the blood glucose sensor in real time, ensuring the real-time, complete and accurate blood glucose and ion data, and enabling continuous blood glucose monitoring of the human body.

[0030] 3. It adopts a stable and reliable power supply design scheme, combining DC-DC chips and LDO chips. Compared with a single DC-DC converter or LDO chip design, it has lower noise, smaller ripple and higher conversion efficiency.

[0031] 4. The circuit is small in size and wearable, which is conducive to the human body wearing it for a long time. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the continuous blood glucose monitoring circuit described in this invention.

[0033] Figure 2 This is a schematic diagram of the main control circuit of the continuous blood glucose monitoring circuit described in this invention.

[0034] Figure 3 This is a schematic diagram of the signal acquisition circuit of the continuous blood glucose monitoring circuit described in this invention.

[0035] Figure 4 This is a schematic diagram of the constant potential circuit and a partial schematic diagram of the signal acquisition circuit of the continuous blood glucose monitoring circuit described in this invention.

[0036] Figure 5 This is a schematic diagram of the constant current circuit and part of the main control circuit of the continuous blood glucose monitoring circuit described in this invention.

[0037] Figure 6 This is a schematic diagram of the power supply circuit for the continuous blood glucose monitoring circuit described in this invention.

[0038] Figure 7 This is a schematic diagram of the front-end processing circuit of the continuous blood glucose monitoring circuit described in this invention.

[0039] Figure 8 This is a partial circuit diagram of the continuous blood glucose monitoring circuit described in this invention.

[0040] Figure 9 This is a schematic diagram of the power supply circuit for the continuous blood glucose monitoring circuit described in this invention. Detailed Implementation

[0041] The continuous blood glucose monitoring circuit of the present invention will be described in detail below with reference to the embodiments and accompanying drawings.

[0042] Example 1

[0043] like Figures 1-9As shown, the continuous blood glucose monitoring circuit measures 58.04mm x 58.04mm and employs a double-sided PCB design. It includes a main control circuit, a signal acquisition circuit, a constant potential circuit, a constant current circuit, and a power supply circuit. The main control circuit is connected to the signal acquisition circuit, the constant potential circuit, and the constant current circuit. The constant potential circuit is connected to the signal acquisition circuit. The power supply circuit is connected to the main control circuit, the signal acquisition circuit, the constant potential circuit, and the constant current circuit to provide power.

[0044] The main control circuit uses the STM32F407VET6 32-bit microcontroller as its core to implement general-purpose I / O port control, SPI communication, serial communication, I2C communication, and real-time operating system configuration. The main control circuit includes a main chip circuit, clock circuit, reset circuit, serial port circuit, screen circuit, storage circuit, and STLINK debug interface circuit. The schematic diagram of the main control circuit is shown below. Figure 2 As shown, the clock circuit is connected to pins 12 and 13 of the main chip circuit, the reset circuit is connected to pin 14 of the main chip circuit, the serial port circuit is connected to pins 68 and 69 of the main chip circuit, the screen circuit is connected to pins 30, 32, 47, 48, 53, 54, 63, 70, and 71 of the main chip circuit, the storage circuit is connected to pins 65, 66, 78-80, and 83 of the main chip circuit, and the STLINK debug interface circuit is connected to pins 72 and 76 of the main chip circuit. The main control circuit is used for inter-circuit communication, signal processing, control logic, and data management. The main chip circuit uses an STM32F407VET6 32-bit microcontroller with an ARM Cortex-M4 core and a main frequency of up to 168MHz. It features high performance and low power consumption, providing strong computing power and facilitating multi-channel signal acquisition and processing. The clock circuit uses an external 8MHz crystal oscillator as the system clock source, and a DS3231M real-time clock chip provides information such as seconds, minutes, hours, days, months, and years. Figure 5This chip features leap year compensation up to 2100 years and a timing accuracy of ±5ppm (±0.432 seconds / day) from -45℃ to 85℃. The main chip communicates with this chip via an I2C bidirectional bus. The 3.3V power input terminals of the main chip are all connected to digital ground (GND) via decoupling capacitors, which are placed as close as possible to the main chip's power pins. The STM32 has three boot modes. In this invention, the boot circuit is configured with both BOOT0 and BOOT1 set to 0, setting the main chip to boot from the user's flash memory. After power-on, the circuit will run automatically. The reset circuit is a low-level reset, consisting of R1 and C3 forming the power-on reset circuit. The main chip, STM32F407VET6, has four universal synchronous / asynchronous receiver transmitters (USART1, USART2, USART3, and USART6) and two universal asynchronous receiver transmitters (UART4 and UART5). The main chip can connect to a PC via the USART1 interface. The main chip communicates with an external screen via an FPC connector to display data. The specific schematic diagram is shown below. Figure 5 As shown. The storage circuit uses a 4-bit SDI0 method to drive the MicroSD card, and the main chip can directly read and write data to the MicroSD card through the SDI0 interface. The main control circuit uses a serial debug interface (SWD) to burn and download programs, and connects to the PC through the SWD interface via an STLINK emulator.

[0045] The signal acquisition circuit mainly detects analog signals, and its schematic diagram is shown below. Figure 3 and 4The signal acquisition circuit consists of an ADS131A04 four-channel high-performance synchronous sampling ADC chip, a front-end processing circuit, and a clock circuit. Pin 2 of one ADS131A04 four-channel high-performance synchronous sampling ADC chip is connected to the front-end processing circuit, and pin 8 of the other ADS131A04 four-channel high-performance synchronous sampling ADC chip is also connected to the front-end processing circuit. Pins 25 and 26 of the ADS131A04 four-channel high-performance synchronous sampling ADC chip are connected to the clock circuit. The signal acquisition circuit first performs front-end processing of the current signal. In the front-end processing circuit, the MAX4238 chip acts as a transimpedance amplifier. The OUT pins of the MAX4238 chips in the two front-end processing circuits are connected to pins 2 and 8 of the two ADS131A04 four-channel high-performance synchronous sampling ADC chips, respectively, converting the analog current signal into an analog voltage signal. Before the analog voltage signal output from the blood glucose sensor (CN119846039A) is input to the ADC chip, it first passes through an RC anti-aliasing filter to remove high-frequency harmonics from the input signal, reducing the interference of high-frequency noise on the blood glucose signal. The -3 dB cutoff frequency is 15.9MHz. The series impedance is relatively low, which can maintain sufficient total harmonic distortion (THD) performance. The analog current signal output from the blood glucose sensor also undergoes low-pass filtering after passing through a front-end processing circuit. The front-end processing circuit uses the MAX4238 low-noise, low-drift, high-precision operational amplifier chip. The two front-end processing circuits are connected to pins 2 and 8 of two ADS131A04 four-channel high-performance synchronous sampling ADC chips, respectively. The schematic diagram of this part is shown below. Figure 7 The working electrode of the blood glucose sensor is connected to the inverting input of the operational amplifier, while the non-inverting input is connected to a reference voltage. The working electrode generates a current signal. Under negative feedback, the input current of the operational amplifier is almost zero, and the voltage across feedback resistors R6 and R7 is approximately equal to the output voltage. Therefore, the current flowing through the feedback resistors can be considered the magnitude of the current to be measured. The signal acquisition circuit uses a dual ADS131A04 four-channel high-performance synchronous sampling ADC chip. This chip has a maximum data rate of 128kSPS and an effective resolution of 20.6 bits (8kSPS). The ADS131A04 operates via an internal system clock ICLK, which is provided by a 16.384MHz crystal oscillator. The chip communicates with the microcontroller via an SPI bus. The analog and digital ground planes of the signal acquisition circuit are connected via a ferrite bead to reduce interference from the digital circuits to the analog circuits.

[0046] The constant potential circuit mainly applies a constant voltage between the working electrode and the reference electrode of the blood glucose sensor to provide a stable constant potential difference, such as... Figure 4As shown, the constant potential circuit includes a DAC8531 low-power digital-to-analog converter chip, an RS8552 operational amplifier, and a REF3130 reference source. Pins 3 and 4 of the DAC8531 low-power digital-to-analog converter chip are connected to pin 5 of the RS8552 operational amplifier through a resistor. The OUT pin of the REF3130 reference source is connected to pin 3 of the RS8552 operational amplifier. Meanwhile, pin 1 of the RS8552 operational amplifier is connected to the positive input terminal of the MAX4238 chip in the signal acquisition circuit through a resistor. First, the REF3130 reference source outputs a constant voltage to provide a reference voltage for the front-end processing circuit and also outputs it to the next stage circuit. The DAC8531 low-power digital-to-analog converter chip generates a voltage signal after being set by the main control circuit. After being divided by high-precision resistors R56, R57, R58, and R59, a stable potential difference is formed between the working electrode and the reference electrode of the blood glucose sensor. The RS8552 operational amplifier features ultra-low noise, offset, and power consumption. It is designed with a two-stage voltage follower to provide extremely high input impedance and signal isolation when connected to a blood glucose sensor.

[0047] The constant current circuit primarily outputs a weak current signal precisely to the extraction electrode of the blood glucose sensor, as shown in the schematic diagram below. Figure 5 As shown, the constant current circuit includes a DAC8531 low-power digital-to-analog converter chip, an OP07 operational amplifier, an OPA2196 operational amplifier, and a relay. Pins 3 and 4 of the DAC8531 low-power digital-to-analog converter chip are connected to pin 3 of the OP07 operational amplifier. Pin 6 of the OP07 operational amplifier is connected to pins 3 and 7 of the OPA2196 operational amplifier via a resistor. Pins 1 and 5 of the OPA2196 operational amplifier are connected to the relay via a resistor. The DAC8531 low-power digital-to-analog converter chip generates a voltage signal after being set by the main control circuit. The voltage signal first passes through a voltage follower formed by the OP07 operational amplifier, which acts as a signal isolation buffer to enhance the voltage driving capability. The voltage signal then flows into a feedback circuit formed by the OPA2196 operational amplifier for signal conversion. R36, R37, R38, and R39 form a high-precision sampling resistor network. As can be seen from the virtual short and virtual open characteristics of the operational amplifier, the output current = input voltage signal / voltage across the sampling resistor. The relay is controlled by the main control circuit and is used to change the direction of the output current.

[0048] The power supply circuit is used to provide a continuous and stable power supply and to charge the lithium battery, such as Figure 7As shown, the power supply circuit includes an IP2325 lithium battery charging chip, a TPS54231 buck chip, a TPS7A4701 linear regulator, an MT3608 boost converter, an AMS1117 linear regulator, a Type-C interface, and a battery interface. The Type-C interface is connected to the IP2325 lithium battery charging chip. Pin 2 of the IP2325 lithium battery charging chip is connected to the battery interface. The battery interface is connected via switches to the V1N pins of the two TPS54231 buck chips and pins 4 and 5 of the MT3608 boost converter. The two TPS54231 buck chips are connected to pin 3 of the AMS1117 linear regulator and pins 13 and 15 of the two TPS7A4701 linear regulators, respectively. This circuit has two main functions: charging the 7.4V lithium battery and providing a stable power supply to the various circuits. The IP2325 boost charging management chip converts the 5V DC voltage input via Type-C to the voltage required by the lithium battery, achieving an 8V / 1.2A output conversion efficiency of up to 93%. The IP2325 also features input voltage limiting, intelligently adjusting the charging current to adapt to the adapter's load capacity. The MT3608 boost converter boosts the lithium battery voltage to 16V to power the operational amplifier in the constant current circuit. This circuit uses two TPS54231 buck converters: one to reduce the lithium battery voltage to 5V to power the DAC chip and relay in the constant current circuit, and the other to provide a low-noise, stable power supply for the signal acquisition and constant potential circuits, in combination with a subsequent LDO chip. This circuit uses two TPS7A4701 low-dropout linear regulators to power the two ADS131A04 chips and the DAC chip in the constant potential circuit. The TPS7A4701 further regulates and filters the voltage after the TPS54231 step-down, providing a stable power supply for the ADC and DAC chips. The AMS1117 low-dropout linear regulator reduces the 5V voltage converted by the TPS54231 to 3.3V, providing a stable power supply for the main control circuit, constant potential circuit, and signal acquisition circuit.

[0049] The aforementioned continuous blood glucose monitoring circuit includes two FPC connectors. One FPC connector is located in the main control circuit for connecting to the screen circuit, and the other FPC connector is located in the signal acquisition circuit, constant current circuit, and constant potential circuit for connecting to the respective circuits (signal acquisition circuit, constant current circuit, and constant potential circuit). The FPC connector is connected to the blood glucose sensor. The blood glucose sensor is connected via the FPC connector to pins 2, 4, and 6 of one ADC chip and pins 4, 6, and 8 of another ADC chip in the signal acquisition circuit, the inverting input terminals of two MAX4238 chips, pin 7 of two RS8552 operational amplifiers in the constant potential circuit, and pins 3 and 6 of the relay in the constant current circuit. The blood glucose sensor is connected to the continuous blood glucose monitoring circuit via an FPC connector. The signal acquisition circuit is responsible for acquiring the analog signal output by the blood glucose sensor. The constant potential circuit is responsible for applying a stable constant voltage between the working electrode and the reference electrode of the blood glucose sensor. The constant current circuit is responsible for accurately outputting a weak current signal to the extraction electrode of the blood glucose sensor. The main control circuit processes and analyzes the digital signal transmitted by the ADC chip, and then stores the data in a MicroSD card. At the same time, it is displayed on an external screen. The power supply circuit provides a stable power supply to the above circuits and charges the lithium battery.

[0050] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A continuous blood glucose monitoring circuit, characterized in that: It includes a main control circuit, a signal acquisition circuit, a constant potential circuit, a constant current circuit, and a power supply circuit. The main control circuit is connected to the signal acquisition circuit, the constant potential circuit, and the constant current circuit. The constant potential circuit is connected to the signal acquisition circuit. The power supply circuit is connected to the main control circuit, the signal acquisition circuit, the constant potential circuit, and the constant current circuit to supply power. The main control circuit is based on the 32-bit microcontroller STM32F407VET6 microcontroller, which is used to realize general I / O port control, SPI communication, serial communication, II2C communication, and real-time operating system configuration. The signal acquisition circuit uses a four-channel high-performance synchronous sampling ADC chip to convert analog signals into digital signals; The constant potential circuit is used to provide a stable constant potential difference; The constant current circuit is used to output a precise, weak current. The power supply circuit is used to provide a continuous and stable power supply and to charge the lithium battery.

2. The continuous blood glucose monitoring circuit according to claim 1, characterized in that: The main control circuit includes a main chip circuit, a clock circuit, a reset circuit, a serial port circuit, a screen circuit, a storage circuit, and an STLINK debug interface circuit. The main chip circuit uses an STM32F407VET6 32-bit microcontroller. The clock circuit, reset circuit, serial port circuit, screen circuit, storage circuit, and STLINK debug interface circuit are respectively connected to the pins of the main chip circuit. The main control circuit is used for inter-circuit communication, signal processing, control logic, and data management.

3. The continuous blood glucose monitoring circuit according to claim 1, characterized in that: The signal acquisition circuit is a multi-channel signal acquisition circuit, consisting of an ADS131A04 four-channel high-performance synchronous sampling ADC chip, a front-end processing circuit, and a clock circuit. The ADS131A04 four-channel high-performance synchronous sampling ADC chip is connected to the front-end processing circuit and the clock circuit, respectively.

4. The continuous blood glucose monitoring circuit according to claim 1, characterized in that: In the front-end processing circuit, the MAX4238 chip is connected to the ADS131A04 four-channel high-performance synchronous sampling ADC chip to convert the analog current signal into an analog voltage signal.

5. The continuous blood glucose monitoring circuit according to claim 1, characterized in that: The constant potential circuit includes a DAC8531 low-power digital-to-analog converter chip, an RS8552 operational amplifier, and a REF3130 reference source. The DAC8531 low-power digital-to-analog converter chip is connected to the RS8552 operational amplifier, and the REF3130 reference source is also connected to the RS8552 operational amplifier. Meanwhile, the RS8552 operational amplifier is connected to the positive input terminal of the MAX4238 chip in the signal acquisition circuit through a resistor to provide a stable potential difference.

6. The continuous blood glucose monitoring circuit according to claim 1, characterized in that: The constant current circuit includes a DAC8531 low-power digital-to-analog converter chip, an OP07 operational amplifier, an OPA2196 operational amplifier, and a relay. The DAC8531 low-power digital-to-analog converter chip is connected to the OP07 operational amplifier, the OP07 operational amplifier is connected to the OPA2196 operational amplifier, and the OPA2196 operational amplifier is connected to the relay, for outputting a precise weak current.

7. The continuous blood glucose monitoring circuit according to claim 1, characterized in that: The power supply circuit includes an IP2325 lithium battery charging chip, a TPS54231 buck chip, a TPS7A4701 linear regulator, an MT3608 boost converter, an AMS1117 linear regulator, a Type-C interface, and a battery interface. The Type-C interface is connected to the IP2325 lithium battery charging chip, which is connected to the battery interface. The battery interface is connected to both the TPS54231 buck chip and the MT3608 boost converter. The TPS54231 buck chip is connected to both the AMS1117 linear regulator and the TPS7A4701 linear regulator.

8. The continuous blood glucose monitoring circuit according to claim 1, characterized in that: It includes two FPC connectors. One FPC connector is located in the main control circuit for connecting to the screen circuit, and the other FPC connector is located in the signal acquisition circuit, constant current circuit, and constant potential circuit. The blood glucose sensor is connected to the ADC chip and MAX4238 chip in the signal acquisition circuit, the RS8552 operational amplifier in the constant potential circuit, and the relay in the constant current circuit through the FPC connector.

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