A dual plate portable electrochemical test system

Abstract

This invention belongs to the field of electrochemical testing technology and discloses a dual-plate portable electrochemical testing system, including an upper plate, a lower plate, an electrochemical biosensor electrode converter, and a mobile terminal APP. The invention adopts an upper and lower plate structure, separating the data programming surface and the sensor interface surface, facilitating the replacement and upgrading of computing resources and the analog front-end separately. The invention hierarchically lays out the three-electrode interface analog circuit and the communication control circuit, and separates the power supply for digital and analog power supplies, which helps reduce mutual interference between the sensor's analog signal lines and digital communication signal lines, improving the stability of electrochemical testing. This invention enables wireless interaction via a mobile terminal and can be portablely powered by an external terminal device, offering flexible usage and facilitating on-site deployment and mobile testing. This invention supports multiple testing modes, including cyclic voltammetry, chronoamperometry, and differential pulse voltammetry, adapting to different electrochemical testing needs.

Description

Technical Field

[0001] This invention belongs to the field of electrochemical testing technology and relates to a dual-plate portable electrochemical testing system. Background Technology

[0002] Electrochemical testing is widely used in water quality detection, human health monitoring, and chemical reaction detection. While existing electrochemical workstations offer high voltage control and current measurement accuracy, their large size and high cost make them unsuitable for on-site testing applications. Application-specific integrated circuits (ASICs), despite their high integration and low power consumption, suffer from long development cycles and insufficient flexibility; changes in the test object, communication method, or accuracy requirements often necessitate redesign. Microprocessor-based electrochemical testing solutions offer advantages in development convenience and portability, but centralizing the sensor analog front-end, analog-to-digital conversion module, and wireless communication module on the same board or chip can easily introduce interference between analog and digital radio frequency signals.

[0003] On the other hand, different application scenarios have varying requirements for system computing resources, communication methods, and sensor interface accuracy. Existing single-board electrochemical testing structures typically fix the programming control section and sensor interface section on the same circuit carrier. When it is necessary to upgrade microcontroller resources, change the wireless communication module, or replace the potentiostat module and digital-to-analog converter module for different three-electrode sensors, it is often necessary to modify or replace the entire circuit, resulting in poor system scalability and reconfigurability. Therefore, it is necessary to provide an electrochemical testing system that separates the programming control function from the sensor interface function, while also considering portability, wireless transmission, and multiple testing modes. Summary of the Invention

[0004] The purpose of this invention is to provide a dual-plate portable electrochemical testing system to solve the problems of high coupling between the programming control part and the sensor interface part, inconvenient system reconfiguration, large interference between analog signals and digital radio frequency signals, and insufficient portability in the prior art.

[0005] The technical solution of this invention: A dual-board portable electrochemical testing system includes an upboard, a downboard, an electrochemical biosensor electrode converter, and a mobile terminal APP. The upboard houses a main control microprocessor, an analog-to-digital converter, a crystal oscillator, and programming pins. The downboard contains an electrochemical detection system circuit, including a dual-channel DAC module, a potentiostat module, a transimpedance amplifier module, a communication module, and a dual-channel LDO power management module. The upboard is configured as the data programming surface, and the downboard as the sensor interface surface. The system allows for replacement of either the upboard or the downboard without altering the sensor interface circuitry, or without changing the main control program framework, thus adapting to different electrochemical testing needs in various scenarios.

[0006] The upboard uses the STM32F103C8T6 main control chip as the main control microprocessor, with an external crystal oscillator providing the working clock. One side has a programming side pin for program burning and debugging, and has a built-in analog-to-digital conversion unit. It is connected to the electrochemical detection system circuit of the downboard via pin headers and sockets.

[0007] The output of the dual DAC module on the downlink board is connected to the input of the potentiostat module. The output of the potentiostat module is connected to the reference electrode interface and counter electrode interface of the three-electrode system through the electrochemical biosensor electrode converter. The input of the transimpedance amplifier module is connected to the working electrode interface of the three-electrode system, and its output is connected to the analog-to-digital converter unit on the uplink board. The potentiostat module and the transimpedance amplifier module together form the three-electrode interface analog circuit. The two inputs of the dual LDO power management module are connected to the USB OTG port of the downlink board and the JTAG port of the uplink board, respectively, and the two outputs are digital power and analog power, respectively. The communication module is a JDY10 Bluetooth module, which is connected to the main control microprocessor through the USART serial port.

[0008] The mobile terminal APP is a smartphone used to send test mode commands, receive test data, display test curves, and extract electrochemical parameters.

[0009] One end of the electrochemical biosensor electrode converter includes a working electrode interface, a reference electrode interface, and a counter electrode interface; the other end of the electrochemical biosensor electrode converter is used to connect a screen-printed electrode.

[0010] The dual-channel LDO power management module includes power inputs for the uplink board and downlink board, used for power supply in development / debugging and deployment / use states, respectively. The dual-channel LDO power management module includes two low-dropout linear regulator circuits, used to convert the externally input 5V voltage into 3.3V operating voltages to supply the digital and analog circuits respectively, so as to achieve decoupling of digital and analog power supplies.

[0011] The main control microprocessor uses I 2The C-bus controls the output test voltage of the external digital-to-analog converter module; the input of the potentiostat module is equipped with two cascaded second-order Butterworth active filters, each using a Sallen-Key structure, with unity-gain buffer stages between adjacent filter units to improve the stability of the input analog signal; the feedback branch of the transimpedance amplifier module is equipped with a feedback resistor and a compensation capacitor, and a resistor is connected in series at the output to achieve stable conversion of the working electrode current signal to a voltage signal and improve sensitivity.

[0012] The communication module and power interface are arranged on the top layer of the downlink board, and the three-electrode interface analog circuit and digital-to-analog conversion module are arranged on the bottom layer. The communication module is placed close to the edge of the circuit board to reduce signal interference within the board.

[0013] During system operation, the externally input 5V voltage is input from the USB OTG port of the downlink board or the JTAG port of the uplink board. It is converted into two independent 3.3V operating voltages by the dual-channel LDO power management module on the downlink board. The digital power supply powers the digital interfaces of the JDY10 Bluetooth module and the dual-channel DAC module on the downlink board, and simultaneously transmits the 3.3V operating voltage to the uplink board via the power pins of the header and socket to power the main control microprocessor. The analog power supply powers the analog circuitry of the three-electrode interface on the downlink board. When the user sends a test mode command to the JDY10 Bluetooth module via the mobile terminal APP, the JDY10 Bluetooth module converts the wireless signal into a serial TTL signal, which is then sent to the main control microprocessor on the uplink board via the USART_RX pin of the header and socket. After parsing the test mode command, the main control microprocessor generates the voltage timing sequence and transmits it via I / O. 2 The C-bus sends data to the dual-channel DAC module, which converts the digital signal into an analog excitation voltage. This analog excitation voltage, after noise removal by a two-stage second-order Butterworth active filter, is sent to the potentiostat module to provide a reference potential for the reference electrode and a driving current for the counter electrode, maintaining a set potential difference between the working electrode and the reference electrode, thus driving an electrochemical reaction on the screen-printed electrode. During the electrochemical reaction, the working electrode generates a weak nA-level current signal, which is converted into a voltage signal by the transimpedance amplifier module. After filtering, the voltage signal is sent to the analog-to-digital converter (ADC) unit built into the uplink board via the ADC_IN pin of the header and socket to complete the analog-to-digital conversion. The main control microprocessor preprocesses the received test data and transmits it to the communication module via the USART serial port. The communication module converts the received test data into a wireless signal and sends it back to the mobile terminal APP. The mobile terminal APP receives the test data, displays the test curve, and extracts the electrochemical parameters.

[0014] The mobile terminal APP can set one or more of the following test modes: cyclic voltammetry, chronoamperometry, and differential pulse voltammetry, and generate the corresponding current-potential curve or current-time curve.

[0015] The beneficial effects of this invention are: 1. The present invention adopts a split-board structure, separating the programming control surface from the sensor interface surface, which facilitates the replacement and upgrading of computing resources and analog front-end separately, and significantly improves the reconfigurability and scalability of the system.

[0016] 2. This invention lays out the three-electrode interface analog circuit and the communication control circuit in a layered manner, and separates the power supply for the digital power supply and the analog power supply, which helps to reduce the mutual interference between the sensor analog signal line and the digital communication signal line and improve the stability of electrochemical testing.

[0017] 3. This invention enables wireless interaction via mobile terminals and can be powered by external terminal devices, making it flexible in use and easy to deploy on-site and for mobile testing.

[0018] 4. This invention supports multiple testing modes, including cyclic voltammetry, chronoamperometry, and differential pulse voltammetry, and can adapt to different electrochemical testing needs. Attached Figure Description

[0019] Figure 1 This is a three-dimensional structural diagram of the dual-plate portable electrochemical testing system of the present invention; Figure 2 This is an exploded view of the structure of the present invention; Figure 3 This is a schematic diagram of the detection process of the present invention; Figure 4 This is a system flowchart of the present invention; Figure 5 This is a comparison of the cyclic voltammetry method and the CHI660E test results of this invention; Figure 6 The results of the time-current method of the present invention and the test results of CHI660E are compared; where (a) is the falling edge of the present invention, (b) is the falling edge of CHI660E, (c) is the rising edge of the present invention, and (d) is the rising edge of CHI660E. Figure 7 This is a comparison of the results of the differential pulse voltammetry method of this invention with those of the CHI660E test; Figure 8 The results of cyclic voltammetry with different electrodes were tested for this invention; where (a) is electrode 250BT, (b) is electrode 110GPH, and (c) is electrode 110BI. Figure 9 The results show the peak value changes in three cyclic voltammetry tests of this invention.

[0020] In the diagram: 1 Downlink board, 2 JTAG port of uplink board, 3 Uplink board, 4 STM32F103C8T6 main control chip, 5 Crystal oscillator, 6 Programming side pins, 7 Electrochemical biosensor electrode converter, 8 Communication module, 9 Three-electrode interface analog circuit, 10 Pin header and socket header, 11 USB OTG port of downlink board, 12 Electrochemical detection system circuit, 13 Screen-printed electrode, 14 Power supply, 15 Mobile terminal APP, 16 Dual-board portable electrochemical testing system. Detailed Implementation

[0021] The specific embodiments of the present invention will be further described below with reference to the accompanying drawings and technical solutions.

[0022] Example A dual-plate portable electrochemical testing system 16, such as Figures 1 to 4 As shown, the system includes a downlink board 1, an uplink board 3, an electrochemical biosensor electrode converter 7, a communication module 8, a three-electrode interface analog circuit 9, a pin header and socket 10, a USB OTG port 11 on the downlink board, and a mobile terminal APP 15. The uplink board 3 is equipped with an uplink JTAG port 2, an STM32F103C8T6 main control chip 4, a crystal oscillator 5, and programming side pins 6; the downlink board 1 is equipped with an electrochemical detection system circuit 12. The uplink board 3 and the downlink board 1 are connected via pin headers and sockets 10, forming a two-board structure with separate upper and lower sections. The uplink board 3 serves as the data programming surface, and the downlink board 1 serves as the sensor interface surface. This structure facilitates upgrading the main control resources and control program of the uplink board without modifying the downlink board's analog interface, and also facilitates replacing the analog front-end of the downlink board without altering the uplink board's program framework, to adapt to the electrochemical testing needs of different application scenarios.

[0023] In this embodiment, the uplink board preferably uses an STM32F103C8T6 main control chip 4 to complete test mode recognition, instruction parsing, DAC control, ADC sampling, data buffering, and communication forwarding. The STM32F103C8T6 main control chip 4 first communicates via I... 2 The C-bus controls the DAC output test voltage on the downlink board; the voltage signal returned from the working electrode is sampled by the built-in ADC of the STM32F103C8T6 main control chip 4, and the sampled data is transferred to memory through the DMA channel to reduce CPU usage during continuous sampling. Downlink board 1 integrates a dual-channel DAC module, a potentiostat module, a transimpedance amplifier module, a communication module, and a dual-channel LDO power management module. The analog voltage output by the DAC is processed by the potentiostat module and applied to the screen-printed electrode 13 to define the reference electrode potential and drive the counter electrode; the weak current signal generated by the working electrode during the electrochemical reaction is converted into a voltage signal by the transimpedance amplifier and then sent to the ADC of uplink board 3 for sampling.

[0024] The potentiostat module has a two-stage cascaded second-order Butterworth active filter at its input. Each filter unit adopts a Sallen-Key structure, and a unity-gain buffer stage is set between adjacent filter units to improve the stability of the input analog voltage. The feedback branch of the transimpedance amplifier is equipped with a feedback resistor and a compensation capacitor to improve system stability and suppress oscillations, thereby improving the readout capability of weak current signals.

[0025] In terms of power supply, this embodiment has two power supply inputs. One is the JTAG port 2 on the uplink board, mainly used for power supply during program burning and development debugging; the other is the USB OTG port 11 on the downlink board, mainly used for the 5V voltage introduced by the power supply 14 during deployment. The external input voltage is regulated by the dual-channel LDO power management module on the downlink board 1 to form a digital 3.3V power supply and an analog 3.3V power supply respectively, so as to achieve decoupling of digital power supply and analog power supply and reduce the interference of digital signal on analog detection signal.

[0026] In terms of communication method, the communication module 8 in this embodiment adopts a JDY10 Bluetooth module and is connected to the STM32F103C8T6 main control chip 4 via USART. After system initialization, the STM32F103C8T6 main control chip 4 first completes ADC, DMA, and I... 2 After configuring the serial communication parameters, the system waits for the mobile terminal 15 to issue a test mode command. Upon receiving the command, the STM32F103C8T6 main control chip 4 controls the DAC to output the corresponding excitation voltage according to the selected test mode, and after sampling, sends the result to the mobile terminal 15 for display and processing via the communication module 8.

[0027] In the experimental verification, the control device used was a CHI660E electrochemical workstation; the electrodes were screen-printed electrodes 13 (models 250BT, 110GPH, and 110BI) manufactured by Metrohm, Switzerland; the test solution was a self-prepared 2 mM potassium ferricyanide / potassium ferrocyanide solution. During testing, the test solution was dropped onto the screen-printed electrode 13, and then connected to the electrochemical biosensor electrode converter 7. The corresponding test waveform was applied to the system consisting of the working electrode, reference electrode, and counter electrode, and the current response of the working electrode was recorded.

[0028] Please see Figure 5As shown, in the cyclic voltammetry test, the system mainly involves the redox process between ferricyanide and ferrousyanide, and the response curve shows one reduction peak and one oxidation peak. After smoothing the collected results, the present invention measured an upper peak current of 4.10557756e-05 A and an upper peak potential of 0.167 V, a lower peak current of -5.49764703e-05 A and a lower peak potential of 0.108 V, with a peak-to-peak potential difference of 59 mV; the CHI660E measured a peak-to-peak potential difference of 62 mV. The theoretical peak-to-peak potential difference is 59 mV, indicating that the results obtained in this embodiment are close to those of the standard equipment.

[0029] Please see Figure 6 As shown, in the chronoamperometry test, since the sampling time of the CHI660E is 1 ms, and the system in this embodiment is prone to high-frequency interference at this sampling frequency, the actual sampling time is set to 5 ms. The test results show that the present invention can obtain current decay or rise curves consistent with the trend of the standard device under both rising and falling edge conditions, and can reflect the response law of the chronoamperometry.

[0030] Please see Figure 7 As shown, in the differential pulse voltammetry test, the results obtained in this embodiment were digitally smoothed to facilitate comparison between the two methods. The results show that the peak current measured by this invention is 2.28716189e-04 A, and the peak potential is 0.1195 V; the peak current measured by the CHI660E is 0.0002292 A, and the peak potential is 0.112 V. The peak positions of both are close, and the overall curves show good symmetry.

[0031] Please see Figure 8 and Figure 9 As shown, the test results for different electrodes indicate that the Au-modified 250BT electrode exhibits a higher peak current, demonstrating that the present invention can distinguish the response differences of electrodes with different sensitivities. In multiple cyclic tests, the peak values ​​for the first three tests were 0.01638 mA, 0.01513 mA, and 0.01318 mA, respectively, with deviations within 4 μA, indicating that the present invention has good repeatability.

Claims

1. A dual-plate portable electrochemical testing system, characterized in that, This dual-board portable electrochemical testing system includes an upboard, a downboard, an electrochemical biosensor electrode converter, and a mobile terminal APP. The upboard is equipped with a main control microprocessor, an analog-to-digital converter, a crystal oscillator, and programming pins. The downboard is equipped with electrochemical detection system circuitry, including a dual-channel DAC module, a potentiostat module, a transimpedance amplifier module, a communication module, and a dual-channel LDO power management module. The upboard is set as the data programming surface, and the downboard is set as the sensor interface surface. The upboard can be replaced without changing the sensor interface circuitry, or the downboard can be replaced without changing the main control program framework, thus adapting to the electrochemical testing needs in different scenarios.

2. The dual-plate portable electrochemical testing system according to claim 1, characterized in that, The uplink board uses an STM32F103C8T6 main control chip as the main control microprocessor, with an external crystal oscillator providing the working clock. It has a programming side pin on one side for program burning and debugging, and a built-in analog-to-digital conversion unit. It is connected to the electrochemical detection system circuit of the downlink board via pin headers and sockets.

3. The dual-plate portable electrochemical testing system according to claim 2, characterized in that, The output of the dual-channel DAC module on the downlink board is connected to the input of the potentiostat module. The output of the potentiostat module is connected to the reference electrode interface and counter electrode interface of the three-electrode system through the electrochemical biosensor electrode converter. The input of the transimpedance amplifier module is connected to the working electrode interface of the three-electrode system, and its output is connected to the analog-to-digital converter unit on the uplink board. The potentiostat module and the transimpedance amplifier module together form a three-electrode interface analog circuit. The two inputs of the dual-channel LDO power management module are connected to the USB OTG port of the downlink board and the JTAG port of the uplink board, respectively, and the two outputs are digital power and analog power, respectively. The communication module is a JDY10 Bluetooth module, which is connected to the main control microprocessor through the USART serial port.

4. The dual-plate portable electrochemical testing system according to claim 3, characterized in that, The mobile terminal APP is a smartphone, used to send test mode commands, receive test data, display test curves, and extract electrochemical parameters.

5. The dual-plate portable electrochemical testing system according to claim 4, characterized in that, One end of the electrochemical biosensor electrode converter includes a working electrode interface, a reference electrode interface, and a counter electrode interface; the other end of the electrochemical biosensor electrode converter is used to connect a screen-printed electrode.

6. The dual-plate portable electrochemical testing system according to claim 5, characterized in that, The dual-channel LDO power management module includes a power supply input for the uplink board and a power supply input for the downlink board, which are used for power supply in development and debugging mode and deployment and use mode, respectively. The dual-channel LDO power management module includes two low-dropout linear regulator circuits, which are used to convert the externally input 5V voltage into 3.3V operating voltages to supply the digital circuits and analog circuits respectively, so as to achieve decoupling of digital power supply and analog power supply.

7. The dual-plate portable electrochemical testing system according to claim 6, characterized in that, The main control microprocessor is controlled via I 2 The C-bus controls the output test voltage of the external digital-to-analog converter module; the input of the potentiostat module is equipped with two cascaded second-order Butterworth active filters, each using a Sallen-Key structure, with unity-gain buffer stages between adjacent filter units to improve the stability of the input analog signal; the feedback branch of the transimpedance amplifier module is equipped with a feedback resistor and a compensation capacitor, and a resistor is connected in series at the output to achieve stable conversion of the working electrode current signal to a voltage signal and improve sensitivity.

8. The dual-plate portable electrochemical testing system according to claim 7, characterized in that, The top layer of the downlink board has a communication module and a power interface, while the bottom layer has a three-electrode interface analog circuit and a digital-to-analog converter module. The communication module is positioned close to the edge of the circuit board to reduce signal interference within the board.

9. The dual-plate portable electrochemical testing system according to claim 8, characterized in that, When the system is working, the externally input 5V voltage is input from the USB OTG port of the downlink board or the JTAG port of the uplink board, and is converted into two independent 3.3V operating voltages by the dual-channel LDO power management module of the downlink board. The digital power supply powers the digital interfaces of the JDY10 Bluetooth module and the dual-channel DAC module on the downlink board, and simultaneously transmits the 3.3V operating voltage to the uplink board through the power pins of the header and socket to power the main control microprocessor. The analog power supply powers the analog circuit of the three-electrode interface on the downlink board. When the user sends a test mode command to the JDY10 Bluetooth module via the mobile terminal APP, the JDY10 Bluetooth module converts the wireless signal into a serial TTL signal, which is sent to the main control microprocessor on the uplink board through the USART_RX pin of the header and socket. After parsing the test mode command, the main control microprocessor generates the voltage timing sequence and transmits it through I... 2 The C-bus sends data to the dual-channel DAC module, which converts the digital signal into an analog excitation voltage. This analog excitation voltage, after noise removal by a two-stage second-order Butterworth active filter, is sent to the potentiostat module to provide a reference potential for the reference electrode and a driving current for the counter electrode, maintaining a set potential difference between the working electrode and the reference electrode, thus driving an electrochemical reaction on the screen-printed electrode. During the electrochemical reaction, the working electrode generates a weak nA-level current signal, which is converted into a voltage signal by the transimpedance amplifier module. After filtering, the voltage signal is sent to the analog-to-digital converter (ADC) unit built into the uplink board via the ADC_IN pin of the header and socket to complete the analog-to-digital conversion. The main control microprocessor preprocesses the received test data and transmits it to the communication module via the USART serial port. The communication module converts the received test data into a wireless signal and sends it back to the mobile terminal APP. The mobile terminal APP receives the test data, displays the test curve, and extracts the electrochemical parameters.

10. The dual-plate portable electrochemical testing system according to claim 9, characterized in that, The mobile terminal APP can be set to one or more of the following test modes: cyclic voltammetry, chronoamperometry, and differential pulse voltammetry, and generate corresponding current-potential curves or current-time curves.

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