Electrochemical detection system and method for early gastric cancer marker in human urine

Abstract

The invention provides an electrochemical detection system and method for an early gastric cancer marker in human urine, and the system comprises a three-electrode system which is inserted into a urine sample to be detected and comprises a reference electrode, an auxiliary electrode and a working electrode; the SWV waveform generation module comprises a square wave generation circuit, a step wave generation circuit, a voltage divider, a voltage bias circuit, a bus switch and a constant potential circuit; the current detection circuit outputs a voltage signal after current-voltage conversion; a low-pass filter circuit; an ADC; the FPGA is used for controlling selective conduction of the step wave generation circuit and the bus switch and generating a current-voltage conversion amplification factor signal of the current detection circuit; and a display. Selective conduction of a reset switch and a bus switch in the step wave generation circuit is controlled through FPGA programming, the current-voltage conversion amplification factor of the current detection circuit is controlled, automatic detection of early gastric cancer markers in human urine is achieved, and the early gastric cancer marker detection circuit has the advantages of being low in power consumption, high in speed, high in precision and high in integration level.

Description

Technical Field

[0001] The present invention relates to the technical field of medical devices, and in particular to an electrochemical detection system and method for early gastric cancer markers in human urine. Background Art

[0002] Gastric cancer is a type of adenocarcinoma malignant tumor that originates from the gastric mucosal epithelium. According to the latest report from the National Cancer Center and the Cancer Hospital of the Chinese Academy of Medical Sciences, gastric cancer is the second most common malignant tumor in my country, second only to lung cancer. With the gradual acceleration of the pace of modern life, changes in the dietary structure of Chinese residents have also led to a tendency for gastric cancer to occur at a younger age. However, early gastric cancer often has no obvious abnormal symptoms, causing patients to often confuse it with chronic diseases such as gastritis and gastric ulcers and miss the best time for treatment. At the same time, the incidence of gastric cancer is mainly concentrated in East Asia and Southeast Asia. Its obvious regional characteristics have led to the lack of attention to its screening research internationally. This field has been in a blank stage for a long time.

[0003] Urine test is a routine clinical testing method. Compared with blood test, urine test has the advantages of simple operation, non-invasiveness, and patient-friendly, and has been widely used in the early screening of various diseases. Researchers have also found tumor markers in human urine that are highly correlated with the incidence of gastric cancer. Therefore, the use of urine testing for early screening of gastric cancer is expected to become an efficient and low-cost clinical technical means, which is of great significance for the diagnosis and treatment of gastric cancer in my country.

[0004] Electrochemical detection is an emerging rapid detection method. Since traditional urine samples need to be collected, transported to centralized facilities and tested using HPLC instruments, these steps will lead to increased costs. In addition, centralized clinical laboratories may have backlogs, which may lead to time differences between sampling and concentration measurement of biological fluids of different samples, which will undoubtedly introduce more variables, all of which will have a negative impact on clinical results. Electrochemical detection is fast, accurate and low-cost, and is suitable for early screening of gastric cancer.

[0005] SWV method is one of the important methods in electrochemical analysis. When choosing electrochemical detection methods, considering the complexity and uncertainty of solutes in the urine environment, the SWV method has greatly improved the specificity of markers and the operability for different samples compared with other detection methods. Its specificity is specifically reflected in that, thanks to the SWV square waveform of this method, the secondary measured differential current has a larger numerical performance than any single measurement value when plotted against the basic step potential. At the same time, the differential current at the voltage consistent with the limiting current of the electroactive component and mass transfer area on the electrode surface can be obtained as 0, which means that the noise for non-target substances will be less than other electrochemical methods. In terms of the differences in different human urine samples, the SWV method has an extremely fast scanning speed. For solution systems with capacitive characteristics, the extremely short scanning time will not cause side reactions and noise currents; and for the scanning range of different potentials, due to each positive and negative pulse impact, the potential without reaction will be maintained at the limiting current and will not induce double-layer capacitance characteristics, which is also an advantage for complex urine environments.

[0006] Miniaturized instruments are an extremely effective means of improving the efficiency of early disease screening. Traditional urine testing instruments cannot achieve rapid home testing, but small blood testing instruments have long been widely used, as well as purely physical blood pressure and heart rate testing instruments, which have contributed to the early screening rate and prevention of various related diseases. As a relatively easy-to-obtain human biochemical sample, urine is extremely suitable for the use of small household testing instruments. Therefore, designing a simple programmable miniaturized automatic electrochemical detection system and method plays a key role in the early screening of gastric cancer.

[0007] Therefore, there is a need for a miniaturized early screening device that can automatically detect gastric cancer markers in human urine by utilizing the advantages of the SWV method, thereby providing an important scientific basis for home self-examination and clinical medical diagnosis for people at potential risk of the disease, and ultimately laying a technical foundation for the development of handheld patient self-examination equipment (blood glucose meters) and clinical high-throughput monitoring equipment. Summary of the invention

[0008] In view of the defects in the prior art, the object of the present invention is to provide an electrochemical detection system and method for early gastric cancer markers in human urine.

[0009] According to one aspect of the present invention, there is provided an electrochemical detection system for early gastric cancer markers in human urine, comprising:

[0010] A three-electrode system, comprising a reference electrode, an auxiliary electrode and a working electrode, wherein the three-electrode system is inserted into a urine sample to be tested;

[0011] The SWV waveform generating module comprises a square wave generating circuit, a step wave generating circuit, a voltage divider, a voltage bias circuit, a bus switch and a constant potential circuit, wherein the square wave generating circuit is used to generate square wave waveforms Vy and Vx, Vx is input to the input end of the step wave generating circuit, and Vy is input to the input end of the voltage divider; the step wave generating circuit feeds back a signal Vz to the square wave generating circuit, and outputs a step wave Vin1 to the bus switch; the voltage divider outputs a square wave Vin2 to the bus switch; the voltage bias circuit outputs a DC voltage Vin3, the bus switch is coupled to the constant potential circuit, and outputs voltage waveforms Vae and Vre, Vae is input to the auxiliary electrode, Vre is input to the reference electrode, and the working electrode outputs a detection result current Iwe;

[0012] A current detection circuit is coupled to the output terminal of the working electrode and outputs a voltage signal Vsig after current-voltage conversion;

[0013] A low-pass filter circuit is coupled to the output end of the current detection circuit and outputs a voltage signal Vout after noise reduction;

[0014] ADC, coupled to the output end of the low-pass filter circuit, outputting a digital signal;

[0015] FPGA, coupled to the output end of the ADC, the FPGA controls the selective conduction of the step wave generating circuit and the bus switch, and generates a current-voltage conversion amplification factor signal of the current detection circuit;

[0016] A display is coupled to the FPGA, and is used to display the detection results and operating status and serve as a control interface.

[0017] Optionally, the square wave generating circuit includes two feedback networks. At the in-phase input end, resistors R1, R2 and the output end of the operational amplifier OP1 constitute positive feedback and output Vy; at the inverting input end, capacitor C1, resistor R3 and the output end of the operational amplifier OP1 constitute negative feedback and output Vx.

[0018] Optionally, the step wave generating circuit comprises a differential circuit, a limiter circuit, an integration circuit and a voltage comparator connected in sequence, wherein:

[0019] Vx obtains positive and negative pulse voltages through the differential circuit;

[0020] After the positive and negative pulse voltages pass through the over-limiting circuit, only the positive pulse voltage remains;

[0021] The integration circuit comprises a resistor R7, an operational amplifier OP2, an integration capacitor C3, a MOS tube M1 and a reset switch Srst, one end of the resistor R7 is connected to the limiter circuit, and the other end is respectively connected to the inverting input end of the operational amplifier OP2; the non-inverting input end of the operational amplifier OP2 is grounded; the integration capacitor C3, the reset switch Srst and the MOS tube M1 are respectively connected in parallel between the inverting input end and the output end of the operational amplifier OP2;

[0022] The voltage comparator comprises an operational amplifier OP3, a resistor R9, a resistor R10 and a resistor R11, the output end of the operational amplifier OP2 is connected to the negative phase input end of the operational amplifier OP3; the positive phase input end of the operational amplifier OP3 is connected to the ground GND through the resistor R9 in one way, and is connected to the power supply VEE through the resistor R10 in another way, and the output end is connected to the MOS tube M1; the resistor R11 is connected between the positive phase input end and the output end of the operational amplifier OP3; the output end of the operational amplifier OP2 outputs a step wave Vin1;

[0023] The FPGA controls the conduction of the reset switch Srst. When the reset switch Srst is closed, the integration capacitor C3 is discharged. When detection needs to start, the FPGA controls the reset switch Srst to be disconnected, so that the integration circuit starts integration and accumulation.

[0024] Optionally, the output end of the operational amplifier OP3 is connected to the MOS transistor M1 via a diode D2, and the output end of the operational amplifier OP3 outputs a voltage Vz via a diode D3.

[0025] Optionally, the voltage divider includes an operational amplifier OP4, an operational amplifier OP5, a capacitor C4, a capacitor C5, a resistor R12 and a resistor R13, wherein:

[0026] The operational amplifier OP4 serves as a first voltage follower, and the operational amplifier OP5 serves as a second voltage follower;

[0027] The positive phase input terminal of the operational amplifier OP4 inputs Vy, and the negative phase input terminal is connected to the output terminal. The output terminal of the operational amplifier OP4 is connected to the resistor R12. The resistor R12 and the resistor R13 are connected in series. The resistor R12, the resistor R13, the capacitor C4, and the capacitor C5 are connected in parallel. The resistor R13 and the capacitor C5 are connected to the ground GND via a wire. The resistor R12 and the resistor R13 are connected to the positive phase input terminal of the operational amplifier OP5 via a wire. The negative phase input terminal of the operational amplifier OP5 is connected to the output terminal. The output terminal of the operational amplifier OP5 outputs a square wave Vin2.

[0028] Optionally, the voltage bias circuit includes a resistor R14, a resistor R15 and an operational amplifier OP6, one end of the resistor R14 is connected to the ground GND, and the other end is connected to the resistor R15, the resistor R15 is connected to the power supply VEE, a wire is led between the resistor R14 and the resistor R15 and connected to the positive input terminal of the operational amplifier OP6, the negative input terminal of the operational amplifier OP6 is connected to the output terminal, and the output terminal of the operational amplifier OP6 outputs a DC voltage Vin3.

[0029] Optionally, the step wave Vin1 is formed into a square wave Vin1' through a bus switch, the square wave Vin2 is formed into a step wave Vin2' through a bus switch, and the DC voltage Vin3 is formed into a DC bias Vin3' through a bus switch;

[0030] The constant potential circuit comprises a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, an operational amplifier OP7 and an operational amplifier OP8, the square wave Vin1' is input to one end of the resistor R16, the other end of the resistor R16 is connected to the resistor R19, the resistor R19 is grounded, and a wire is led out between the resistor R16 and the resistor R19 and connected to the positive phase input end of the operational amplifier OP7; the step wave Vin2' is input to one end of the resistor R17, the other end of the resistor R17 is connected to the negative phase input end of the operational amplifier OP7, and the output end of the operational amplifier OP7 outputs Vae;

[0031] The DC bias Vin3' is input to one end of the resistor R18, and the resistor R18 and the resistor R20 are connected to the resistor R17 via a wire. The resistor R20 is connected to the negative input and output of the operational amplifier OP8, and Vre is input to the positive input of the operational amplifier OP8.

[0032] Optionally, the current detection circuit includes an operational amplifier OP9, an operational amplifier OP10, a capacitor C6, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27 and a 4:1 multiplexer;

[0033] The operational amplifier OP9, the capacitor C6, the resistor R21, the resistor R22, the resistor R23, the resistor R24 ​​and the 4:1 multiplexer form a current-to-voltage conversion circuit with variable gain, the positive input terminal of the operational amplifier OP9 is grounded, and the negative input terminal is connected in parallel to the input terminal of the 4:1 multiplexer through the resistor R21, the resistor R22, the resistor R23 and the resistor R24 ​​respectively, the detection result current Iw is input to the negative input terminal of the operational amplifier OP9, the capacitor C6 is connected in parallel between the negative input terminal and the output terminal of the operational amplifier OP9, the capacitor C6 is used as a voltage holding capacitor, and the 4:1 multiplexer selects the smallest resistor among the resistor R21, the resistor R22, the resistor R23 and the resistor R24 ​​by default to obtain the maximum current detection range;

[0034] The output end of the operational amplifier OP9 is connected to the negative phase input end of the operational amplifier OP10 through the resistor R25, the positive phase input end of the operational amplifier OP10 is grounded through the resistor R26, and the resistor R27 is connected in parallel between the negative phase input end and the output end of the operational amplifier OP10 to form a voltage amplification and inversion circuit.

[0035] Optionally, the low-pass filter circuit includes a resistor R28, a resistor R29, a resistor R30, a resistor R31, a capacitor C7, a capacitor C8 and an operational amplifier OP11;

[0036] The resistor R28 and the resistor R29 are connected in series and connected to the non-inverting input terminal of the operational amplifier OP11. The resistor R29 and the non-inverting input terminal of the operational amplifier OP11 are connected to the capacitor C8 via a wire and grounded. The resistor R28 and the resistor R29 are connected to the output terminal of the operational amplifier OP11 via the capacitor C7.

[0037] One end of the resistor R30 is grounded, and the other end is connected to the negative input terminal of the operational amplifier OP11. The resistor R30 and the negative input terminal of the operational amplifier OP11 are connected to the output terminal of the operational amplifier OP11 via the resistor R31.

[0038] According to another aspect of the present invention, there is provided a method for electrochemical detection of early gastric cancer markers in human urine, which is implemented by using the above-mentioned electrochemical detection system for early gastric cancer markers in human urine, and the method comprises:

[0039] Place the three-electrode system into the urine sample to be tested;

[0040] FPGA controls the selective conduction of the SWV waveform generation module to generate the required SWV waveform;

[0041] The FPGA controls the selective conduction of the bus switch to apply the required SWV waveform to the three-electrode system;

[0042] The FPGA-controlled current detection circuit automatically adapts the amplification factor of the current-voltage conversion according to the detection result current of the three-electrode system;

[0043] When the waveform is applied for a preset number of times, the detection is stopped and the detection signal waveform is stored in the FPGA. After FPGA data processing, the test result of the gastric cancer marker concentration in the urine sample is output.

[0044] Compared with the prior art, the present invention has at least one of the following beneficial effects:

[0045] The present invention controls the selective conduction of the reset switch and bus switch in the step wave generating circuit through FPGA programming, and controls the current-voltage conversion magnification of the current detection circuit, thereby realizing the automatic detection of early gastric cancer markers in human urine. Compared with traditional urine detection methods, the system of the present invention has the characteristics of miniaturization, low power consumption, high speed, high precision and high integration, providing advantages in portability, test efficiency and cost for handheld patient self-examination equipment. The system also provides a highly feasible and referenceable electrochemical detection circuit system for other electrochemical methods to detect small molecule markers in various complex solution systems in the future. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Other features, objects and advantages of the present invention will become more apparent from the detailed description of non-limiting embodiments made with reference to the following drawings:

[0047] Figure 1 It is a schematic diagram of the overall structure of an electrochemical detection system in one embodiment of the present invention;

[0048] Figure 2 It is a structural block diagram of a circuit system on a PCB board in one embodiment of the present invention;

[0049] Figure 3 Schematic diagram of the circuit structure of a square wave generating circuit in one embodiment of the present invention;

[0050] Figure 4 Schematic diagram of the circuit structure of a step wave generating circuit in one embodiment of the present invention;

[0051] Figure 5 A schematic diagram of the circuit structure of a voltage divider in one embodiment of the present invention;

[0052] Figure 6 Schematic diagram of the circuit structure of a voltage bias circuit in one embodiment of the present invention;

[0053] Figure 7 Schematic diagram of the circuit structure of a constant potential circuit in one embodiment of the present invention;

[0054] Figure 8 Schematic diagram of the circuit structure of a current detection circuit in one embodiment of the present invention;

[0055] Fig. 9 Schematic diagram of the circuit structure of a low-pass filter circuit in one embodiment of the present invention;

[0056] Fig.10 A schematic diagram of potential-time input of square wave voltammetry in one embodiment of the present invention;

[0057] Fig.11 A schematic diagram of detailed waveform parameters of square wave voltammetry in one embodiment of the present invention;

[0058] Fig.12 Schematic diagram of a signal processing method for detecting a signal in one embodiment of the present invention, (a) is a waveform of a detected differential current signal after applying a single cycle SWV signal, (b) is a waveform after data processing;

[0059] Fig.13 A control logic block diagram of an electrochemical detection system in one embodiment of the present invention;

[0060] Fig.14 FIG. 4 is a flow chart of signal processing of FPGA in one embodiment of the present invention. DETAILED DESCRIPTION

[0061] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0062] Reference Figure 1 An electrochemical detection system for early gastric cancer markers in human urine provided by an embodiment of the present invention includes a three-electrode system, a SWV waveform generation module, a current detection circuit, a low-pass filter circuit, an ADC, an FPGA and a display. The three-electrode system includes a reference electrode, an auxiliary electrode and a working electrode. The three-electrode system is inserted into a urine sample to be tested. Exemplarily, the three-electrode system includes a gold sheet working electrode, a platinum wire auxiliary electrode, and a silver chloride reference electrode; the SWV waveform generation module, the current detection circuit, the low-pass filter circuit, the ADC, and the FPGA can be integrated into a circuit on a PCB board. The circuit system block diagram on the PCB board is shown in FIG. Figure 2As shown, it includes multiple key components and modules to realize signal input, amplification, reception and output processing; specifically, the SWV waveform generating module includes a square wave generating circuit, a step wave generating circuit, a voltage divider, a voltage bias circuit, a bus switch and a constant potential circuit. The square wave generating circuit is used to generate square wave waveforms (i.e., square wave signals) Vy and Vx. The frequencies of the square wave signals Vx and Vy are the same, the amplitude of Vx is greater than the amplitude of Vy, Vx is input to the input end of the step wave generating circuit, and Vy is input to the input end of the voltage divider; the step wave generating circuit feeds back a signal Vz to the square wave generating circuit, and outputs a step wave Vin1 to the bus switch; the voltage divider outputs a square wave Vin2 to the bus switch; the voltage bias circuit outputs a DC voltage Vin3, Vin1~Vin3 are used as the input of the constant potential circuit, the bus switch is coupled to the constant potential circuit, and outputs voltage waveforms Vae and Vre, and the reference electrode and the auxiliary electrode of the three-electrode system are coupled to the output end of the constant potential circuit. , Vae is input as the auxiliary electrode, Vre is input as the reference electrode, the SWV waveform generating module serves as the analog front end of the three-electrode system, provides the waveform required for the electrochemical test, and the working electrode outputs the detection result current Iwe; the current detection circuit is coupled to the output end of the working electrode, and outputs the voltage signal Vsig after current-voltage conversion; the low-pass filter circuit is coupled to the output end of the current detection circuit, and outputs the voltage signal Vout after noise reduction; the ADC is coupled to the output end of the low-pass filter circuit, and outputs a digital signal; the programmable FPGA is coupled to the output end of the ADC, and the FPGA controls the selective conduction of the step wave generating circuit and the bus switch, thereby controlling whether the SWV waveform is applied to the three-electrode system, and generating a current-voltage conversion amplification factor signal of the current detection circuit; the display is coupled to the FPGA, and the FPGA controls the display of the display. The display is used to display the detection results and operating status, and serves as a control interface for controlling the start of the detection.

[0063] Since there are many impurities in the urine system, square wave voltammetry (SWV) is required. The traditional SWV method requires the use of an electrochemical workstation. The system in the embodiment of the present invention is a miniaturized improvement of the electrochemical workstation in a specific scenario. In the embodiment of the present invention, the signal path in the circuit system on the PCB board is: the SWV waveform generation module is used to generate the voltage waveforms Vre and Vae required for square wave voltammetry (SWV), which are respectively added to the reference electrode RE and the auxiliary electrode AE ​​of the three-electrode system. The three-electrode system is used to implement electrochemical detection of early gastric cancer markers in human urine. The potential of its working electrode WE is fixed to 0V by the current detection circuit, and the current Iwe is output. The current detection circuit is connected to the working electrode WE, detects Iwe and outputs a voltage signal Vsig. The voltage signal Vsig is filtered out of its high-frequency noise by a low-pass filter circuit. The noise-reduced signal Vout is converted into a digital signal by an ADC, and the digital signal is input to the FPGA for data processing, and then the FPGA controls the display. As a programmable controller, FPGA controls the conduction of switches or multiplexers such as the reset switch control signal Srst, the bus switch control signal Sin, and the 4:1 multiplexer control signals Sa and Sb in the current detection circuit by sending high-level signals to different modules or circuits, thereby controlling the selective conduction of the step wave generating circuit and the bus switch, and generating a current-voltage conversion amplification factor signal of the current detection circuit. Through the combination and coordinated work of various circuits or modules, the electrochemical detection of early gastric cancer markers in human urine can be carried out in a programmable and automated manner.

[0064] Reference Figure 3 In some embodiments, the square wave generating circuit includes an operational amplifier OP1, resistors R1 to R4 and a capacitor C1, an input voltage Vz, and output voltages Vx and Vy. The square wave generating circuit includes two feedback networks. At the in-phase input end, resistors R1, R2 and the output end of the operational amplifier OP1 form positive feedback and output Vy; at the inverting input end, capacitor C1, resistor R3 and the output end of the operational amplifier OP1 form negative feedback and output Vx through resistor R4. Before starting detection, the potential of the positive input end of the operational amplifier OP1 is 0, and the potential of its negative input end is Vz, Vz≠0, that is, a voltage difference is caused at the input end of the operational amplifier OP1, which can speed up the establishment time from the start of detection to the stable output of the square wave. Because the amplification factor of the ideal operational amplifier is infinite, the output voltage is saturated, so the high level and low level of the square wave Vx are positive and negative saturation voltages, respectively. Vy is a square wave signal obtained by dividing Vx by resistors R1 and R2, and its high and low levels are less than Vx.

[0065] Reference Figure 4In some embodiments, the step wave generating circuit includes a differential circuit, a limiter circuit, an integral circuit and a voltage comparator connected in sequence, wherein: the voltage stabilizing diodes ZD1 and ZD2 are connected in series, the absolute values ​​of the forward and reverse voltages of the square wave generating circuit output Vx are greater than the stabilizing voltage (usually equal to the forward power supply voltage 5V), the step wave generating circuit receives the square wave Vx output by the square wave generating circuit as input, the capacitor C2 and the resistor R5 form a differential circuit, and Vx obtains positive and negative pulse voltages after passing through the differential circuit; the diode D1 and the resistor R6 form a limiter circuit, and the positive and negative pulse voltages only have a positive pulse voltage after passing through the limiter circuit; the integral circuit includes a resistor R7, an operational amplifier OP2, an integral capacitor C3, a MOS tube M1 and a reset switch Srst, one end of the resistor R7 is connected to the limiter circuit, and the other end is respectively connected to the inverting input terminal of the operational amplifier OP2; the non-inverting input terminal of the operational amplifier OP2 is grounded ; The integrating capacitor C3, the reset switch Srst and the MOS tube M1 are respectively connected in parallel between the inverting input terminal and the output terminal of the operational amplifier OP2; the voltage comparator includes the operational amplifier OP3, the resistor R9, the resistor R10 and the resistor R11, and the output terminal of the operational amplifier OP2 is connected to the negative input terminal of the operational amplifier OP3; the positive input terminal of the operational amplifier OP3 is connected to the ground GND through the resistor R9 in one way, and is connected to the power supply VEE through the resistor R10 in the other way, and the output terminal is connected to the MOS tube M1; the resistor R11 is connected between the positive input terminal and the output terminal of the operational amplifier OP3; the output terminal of the operational amplifier OP2 outputs a step wave Vin1; when there is no pulse voltage, the output terminal voltage of the operational amplifier OP2 remains unchanged, and when the next positive pulse voltage arrives, the output terminal voltage of the operational amplifier OP2 is integrated on the basis of the original voltage, so that the integration circuit can play the role of integration and accumulation. FPGA controls the conduction of reset switch Srst. When reset switch Srst is closed, integral capacitor C3 is discharged. When detection needs to be started, FPGA controls reset switch Srst to be disconnected, so that the integral circuit starts to integrate and accumulate. Specifically, when the output voltage of operational amplifier OP2 in the integral circuit is added to the comparison voltage of the voltage comparator, the output of operational amplifier OP3 in the voltage comparator outputs a positive voltage, so that MOS tube M1 is turned on and integral capacitor C3 is discharged. At this time, the output of operational amplifier OP2 jumps from a negative value to zero. After the jump, the output of operational amplifier OP3 is a negative value, and MOS tube M1 is turned off, so that the integral circuit starts to integrate and accumulate again, and so on, forming a step wave. Reset switch Srst is controlled by the signal of FPGA. When reset switch Srst is closed, integral capacitor C3 is discharged. When detection needs to be started, reset switch Srst is disconnected, so that the integral circuit starts to integrate and accumulate.

[0066] In some implementations, the output end of the operational amplifier OP3 is connected to the MOS tube M1 through the diode D2 to ensure that the voltage flows through the diode D2 in the forward direction, thereby preventing the voltage of the square wave generating circuit from affecting the step wave generating circuit. The output end of the operational amplifier OP3 outputs the voltage Vz through the diode D3, so that a voltage difference is formed between the positive and negative input ends of the operational amplifier OP1 in the square wave generating circuit, so that the square wave generating circuit starts oscillating faster.

[0067] Reference Figure 5 In some embodiments, the voltage divider includes an operational amplifier OP4, an operational amplifier OP5, a capacitor C4, a capacitor C5, a resistor R12, and a resistor R13, wherein: the operational amplifier OP4 is used as a first voltage follower, and the operational amplifier OP5 is used as a second voltage follower; unlike Vx output by the operational amplifier OP1, since Vy is output by the non-inverting input terminal of the operational amplifier OP1, it needs to pass through Figure 5 The operational amplifier OP4 is configured such that the positive phase input terminal of the operational amplifier OP4 inputs Vy, the negative phase input terminal is connected to the output terminal, the output terminal of the operational amplifier OP4 is connected to the resistor R12, the resistor R12 and the resistor R13 are connected in series, the resistor R12 and the resistor R13, the capacitor C4 and the capacitor C5 are connected in parallel, the resistor R13 and the capacitor C5 are connected to the ground GND via a wire, the resistor R12 and the resistor R13 are led out via a wire and connected to the positive phase input terminal of the operational amplifier OP5, the negative phase input terminal of the operational amplifier OP5 is connected to the output terminal, and the output terminal of the operational amplifier OP5 outputs a square wave Vin2.

[0068] Since the output resistance of the Vy port of the square wave generating circuit is not small enough, an operational amplifier OP4 is added to the voltage divider as a voltage follower. Similarly, the output resistance directly output after the voltage division of resistors R12 and R13 is not small enough, and an operational amplifier OP5 needs to be added as a voltage follower to improve the load capacity of the voltage divider circuit. The signal is filtered by capacitor C4 (the capacitance value can be 2.2μF) and capacitor C5 (the capacitance value can be 10nF), and then divided by resistors R12 and R13, and the square wave Vin2 is output through the voltage follower.

[0069] Reference Figure 6 In some embodiments, the voltage bias circuit includes a resistor R14, a resistor R15 and an operational amplifier OP6, one end of the resistor R14 is connected to the ground GND, and the other end is connected to the resistor R15, the resistor R15 is connected to the power supply VEE, the resistor R14 and the resistor R15 are connected to the positive input terminal of the operational amplifier OP6 through a wire, the negative input terminal of the operational amplifier OP6 is connected to the output terminal, the operational amplifier OP6 forms a voltage follower, which has a strong load capacity, and the output terminal of the operational amplifier OP6 outputs a DC voltage Vin3.

[0070] In some embodiments, the bus switch has three independent switches, and Vin1 passes through one of the switches to connect to Vin1', that is, the step wave Vin1 is converted into a square wave Vin1' through the bus switch. Similarly, the square wave Vin2 is converted into a step wave Vin2' through the bus switch, and the DC voltage Vin3 is converted into a DC bias Vin3' through the bus switch. Sin controls whether the bus switch is turned on or off. Figure 7 The constant potential circuit includes a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, an operational amplifier OP7 and an operational amplifier OP8. The square wave Vin1' is input to one end of the resistor R16, the other end of the resistor R16 is connected to the resistor R19, the resistor R19 is grounded, and a wire is drawn between the resistor R16 and the resistor R19 to connect to the positive phase input terminal of the operational amplifier OP7; the step wave Vin2' is input to one end of the resistor R17, the other end of the resistor R17 is connected to the negative phase input terminal of the operational amplifier OP7, and the output terminal of the operational amplifier OP7 outputs Vae; the DC bias Vin3' is input to one end of the resistor R18, the wire is drawn between the resistor R18 and the resistor R20 to connect to the resistor R17, the resistor R20 is connected to the negative phase input terminal and the output terminal of the operational amplifier OP8, and Vre is input to the positive phase input terminal of the operational amplifier OP8.

[0071] Since Vae and Vre are connected through the electrodes in the three-electrode system, the constant potential circuit can be regarded as a voltage adder and subtractor, and there is a voltage follower composed of operational amplifier OP8 on its feedback loop. The output end of operational amplifier OP7, the three-electrode system, and the positive input end of operational amplifier OP8 are connected to form negative feedback at the output end of the constant potential circuit. This circuit structure will subtract the three waveforms of Vin1, Vin2, and Vin3, that is, the waveform after Vin1-Vin2-Vin3 is applied to the corresponding electrode of the three-electrode system. When the resistance values ​​of resistors R16~R20 are equal, Vre=Vin2'+Vin3'-Vin1', and because the voltage on the working electrode WE is set to 0V in the current detection circuit, the voltage difference between the working electrode WE and the reference electrode RE is -Vre=Vin1'-Vin2'-Vin3', among which Vin1' is a square wave, Vin2' is a step wave, and Vin3' is a DC bias. After addition and subtraction operations, the SWV waveform can be obtained, and Vre is the SWV waveform.

[0072] Reference Figure 8In some embodiments, the current detection circuit includes an operational amplifier OP9, an operational amplifier OP10, a capacitor C6, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27 and a 4:1 multiplexer; the operational amplifier OP9, the capacitor C6, the resistor R21, the resistor R22, the resistor R23, the resistor R24 ​​and the 4:1 multiplexer constitute a current-to-voltage conversion circuit with a variable gain, the positive input terminal of the operational amplifier OP9 is grounded, the negative input terminal is connected in parallel to the input terminal of the 4:1 multiplexer through the resistor R21, the resistor R22, the resistor R23 and the resistor R24, the detection result current Iw is input to the negative input terminal of the operational amplifier OP9, the capacitor C6 is connected in parallel between the negative input terminal and the output terminal of the operational amplifier OP9, the capacitor C6 is used as a voltage holding capacitor, and the 4:1 multiplexer selects the resistors R21, R22, R23 and R24 by default. The smallest resistance in the circuit is used to obtain the maximum current detection range; specifically, when the FPGA recognizes that the difference between the maximum and minimum values ​​of the output current Iwe of the three-electrode system detected in the detection range is too large, the FPGA sends out 2-bit selection signals Sa and Sb to control the selection of 4 paths (R21-R24), and automatically connects the resistor with a smaller resistance value to the path through the 4:1 multiplexer, so as to adapt to the best current detection range and obtain the best detection accuracy; the output end of the operational amplifier OP9 is connected to the negative phase input end of the operational amplifier OP10 through the resistor R25, the positive phase input end of the operational amplifier OP10 is grounded through the resistor R26, and the resistor R27 is connected in parallel between the negative phase input end and the output end of the operational amplifier OP10 to form a voltage amplification and reverse circuit. Because the gain of the current-voltage conversion circuit is small, it is necessary to add another amplifier for amplification, and the output voltage of the output end of the operational amplifier OP9 is a negative voltage, which needs to be converted to a positive voltage before entering the ADC. The detection result current Iwe is amplified to the maximum allowable voltage range, and then passes through the ADC to obtain the best detection accuracy.

[0073] In the embodiment of the present invention, the current-voltage conversion magnification of the current detection circuit depends on Figure 8 The resistance value of the resistor connected in series at both ends of the capacitor C6 is, Figure 8 The circuits of 4 different resistance values ​​of resistors R21 to R24 are provided. The gating behavior of the 4:1 multiplexer is controlled by the 2-bit gating signals Sa and Sb sent by the FPGA to realize the selection of the 4:1 multiplexer. According to the magnitude of the detection result current Iwe, the FPGA automatically selects the most suitable resistor among the 4 resistors by gating different resistors, and automatically changes the current-voltage conversion magnification of the current detection circuit, thereby determining the optimal current-voltage conversion magnification.

[0074] Reference Fig. 9In some embodiments, the low-pass filter circuit plays a role in filtering high-frequency noise. The low-pass filter circuit includes a resistor R28, a resistor R29, a resistor R30, a resistor R31, a capacitor C7, a capacitor C8 and an operational amplifier OP11; the resistor R28 and the resistor R29 are connected in series and connected to the positive phase input terminal of the operational amplifier OP11, the resistor R29 and the positive phase input terminal of the operational amplifier OP11 are connected to the capacitor C8 via a wire and grounded, and the resistor R28 and the resistor R29 are connected to the output terminal of the operational amplifier OP11 via the capacitor C7; one end of the resistor R30 is grounded, and the other end is connected to the negative phase input terminal of the operational amplifier OP11, and the resistor R30 and the negative phase input terminal of the operational amplifier OP11 are connected to the output terminal of the operational amplifier OP11 via the resistor R31.

[0075] Fig.10 Figure 2 shows a single cycle SWV waveform potential-time schematic diagram. Fig.10 As shown, the potential signal of this method appears as a periodic square wave pulse on the time axis, and its main features are as follows. Square wave potential signal: In square wave voltammetry, the input potential is applied to the electrochemical system in the form of a square wave. The potential changes in the image appear as periodic rectangular pulses, each of which contains two main stages, namely a rising stage and a falling stage. The potential rises rapidly from the baseline potential to the set high potential in the rising stage, and then quickly drops back to the baseline potential in the falling stage, forming a complete cycle. In each cycle, the starting voltage of the SWV waveform scan is -518mV, and the scanning end voltage is 0V. After applying the above SWV waveform, the output current Iwe of the current detection circuit fluctuates in the range of 0 to 3mA in one cycle.

[0076] Fig.11 Figure 2 shows a schematic diagram of detailed parameters of the SWV waveform. Fig.11 As shown, Fig.10 A single cycle of the image is magnified and the square wave potential signal, frequency, potential amplitude and other information are marked. Potential amplitude: In the image, the amplitude of the square wave potential signal refers to the change in the peak value of the potential pulse relative to the baseline potential, and its value is Esw = 25.0mV, ΔE = 1.5mV; Frequency: The frequency of the square wave potential signal repetition, this system selects and adjusts it at 150-250Hz to optimize the signal response characteristics and noise suppression capabilities, and the typical value is τ = 1 / 195.4Hz = 5.11ms.

[0077] based on Fig.10 and Fig.11The single-cycle SWV waveform shown scans multiple cycles and applies multiple SWV waveforms. Each time Iwe passes through the current detection circuit, the low-pass filter circuit, and the ADC, the corresponding detection result is stored in the FPGA. The average value of the multiple stored detection results is taken as the test value of the gastric cancer marker concentration in human urine. Compared with the preset value, the early screening result of gastric cancer using urine testing is obtained.

[0078] Fig.12 The figure shows a schematic diagram of the signal processing method of the detection signal, showing the waveform of the detected differential current signal after applying a single cycle SWV signal and the waveform after data processing. Fig.12 As shown in (a), due to the different solution components, the current difference between the detection data graph containing the early marker and the marker data graph that needs to be stored and processed in advance is large and cannot be directly compared, so the baseline needs to be subtracted. Fig.12 As shown in (b), the peak signal difference of the data minus the baseline is large, and the signal difference of the non-peak value is small. The difference of the differential current peak value can be used as the detection result. When actually performing a test containing early gastric cancer markers, it is necessary to use the image without early markers as the preset value, store it after processing, and then perform the same baseline processing to compare the peak values. The peak difference between each sample and the preset value is the basis for determining the marker concentration.

[0079] Fig.13 The control logic block diagram of the miniaturized programmable automatic electrochemical detection system is shown, including but not limited to the application of multi-cycle SWV waveform and the acquisition of detection results, including the following steps:

[0080] Reset: The reset switch Srst in the step wave generating circuit is closed for a period of time, controlling the step wave generating circuit to generate the required SWV waveform;

[0081] Apply waveform: the reset switch Srst is disconnected, Sin is controlled to open the bus switch, the SWV waveform is applied once and then the bus switch is closed, and the current continues for a period of time;

[0082] Determine whether the maximum value of the detection result current Iwe exceeds the measurement limit of the current detection circuit;

[0083] If the maximum value of the current Iwe of the detection result exceeds the measurement limit of the current detection circuit, the current-voltage amplification factor of the current detection circuit is reduced through switches Sa and Sb; if the maximum value of the current Iwe of the detection result does not exceed the measurement limit of the current detection circuit, it is further determined whether the maximum value of the current Iwe of the detection result is less than half of the measurement limit of the current detection circuit;

[0084] If the maximum value of the current Iwe of the detection result is less than half of the measurement limit of the current detection circuit, the current-voltage amplification factor of the current detection circuit is increased through switches Sa and Sb; if the maximum value of the current Iwe of the detection result is not less than half of the measurement limit of the current detection circuit, it is reset, that is, the reset switch Srst in the step wave generating circuit is closed, and the step wave generating circuit is controlled to be turned on;

[0085] Continuously apply waveform: the reset switch Srst is disconnected, Sin is controlled to open the bus switch, and the SWV waveform is applied;

[0086] After N waveforms have been applied continuously, the detection is stopped, the bus switch is controlled to be closed, and the average value of the N detection results is output.

[0087] In the above embodiment of the present invention, the SWV waveform generation module is coupled to the reference electrode and the auxiliary electrode in the three-electrode system, and is used to apply the voltage waveform required for electrochemical detection on the three electrodes. The current detection circuit is coupled to the output end of the working electrode of the three-electrode system, and the output signal passes through the current detection circuit and the low-pass filter circuit to realize current-voltage conversion and noise reduction; the signal waveform after noise reduction enters the FPGA through the ADC for data post-processing and is displayed on the display. The FPGA generates the reset switch control signal Srst, the bus switch control signal Sin, the 4:1 multiplexer control signals Sa and Sb of the step wave generation circuit, and the selective conduction of the reset switch and the bus switch in the step wave generation circuit is controlled by FPGA programming, so as to realize the automatic detection of gastric cancer markers in human urine. Compared with traditional urine detection methods, the system has the characteristics of miniaturization, low power consumption, high speed, high precision and high integration, and provides portability, test efficiency and cost advantages for handheld patient self-examination equipment. The system also provides a highly feasible and referenceable electrochemical detection circuit system for other electrochemical methods to detect small molecule markers in various complex solution systems in the future.

[0088] It should be noted that, for other solution systems suitable for square wave voltammetry, the system provided by the above embodiment of the present invention can also realize automatic detection. In other solution systems, if it is necessary to change various parameters of the SWV method (such as Fig.11 Medium frequency, etc.), it is only necessary to change the circuit element parameters in the above embodiment of the present invention, such as the resistance value of the resistor, without changing the circuit structure and the FPGA program. The system has strong versatility.

[0089] Based on the same inventive concept, another embodiment of the present invention provides an electrochemical detection method for early gastric cancer markers in human urine, which is implemented using the above-mentioned electrochemical detection system for early gastric cancer markers in human urine. The method comprises the following steps:

[0090] S1. Place the three-electrode system into the urine sample to be tested;

[0091] S2, FPGA controls the selective conduction of the SWV waveform generation module to generate the required SWV waveform;

[0092] S3, FPGA controls the selective conduction of the bus switch to apply the required SWV waveform to the three-electrode system;

[0093] S4, FPGA controls the current detection circuit to automatically adapt the amplification factor of the current-voltage conversion according to the detection result current of the three-electrode system;

[0094] S5. When the waveform is applied for a preset number of times, the detection is stopped, and the detection signal waveform is stored in the FPGA. After FPGA data processing, the test result of the gastric cancer marker concentration in the urine sample is output.

[0095] Fig.14 The signal processing flow of the FPGA of the above-mentioned miniaturized programmable automatic electrochemical detection system is shown, that is, the implementation method of obtaining the detection results. It includes the following processes:

[0096] Storage of detection signals: The three-electrode system outputs Iwe, which is stored in the FPGA after passing through the current detection circuit, low-pass filter circuit and ADC;

[0097] Signal processing: In the FPGA, the detection signal waveforms of N cycles are subtracted from the corresponding baselines to obtain N peaks and take the average value, which is the final detection peak value;

[0098] Result comparison: The preset peak value pre-stored in the FPGA is used as the threshold for judging the early screening results of gastric cancer, and compared with the detection peak value to obtain the early screening results of gastric cancer;

[0099] Results show: The results of early screening for gastric cancer are displayed on the monitor.

[0100] In the above embodiment of the present invention, the programmable FPGA controls the selective conduction of the reset switch and the bus switch in the step wave generating circuit, and controls the current-voltage conversion magnification of the current detection circuit, thereby realizing the automatic detection of early gastric cancer markers in human urine. Compared with traditional urine detection methods, the system in the above embodiment of the present invention has the characteristics of miniaturization, low power consumption, high speed, high precision and high integration, providing advantages in portability, test efficiency and cost for handheld patient self-examination equipment. The system also provides a highly feasible and referenceable electrochemical detection circuit system for other electrochemical methods to detect small molecule markers in various complex solution systems in the future.

[0101] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art can make various modifications or variations within the scope of the claims, which does not affect the essence of the present invention. The above preferred features can be used in any combination without conflicting with each other.

Claims

1. An electrochemical detection system for early gastric cancer markers in human urine, characterized in that: include: A three-electrode system, comprising a reference electrode, an auxiliary electrode and a working electrode, wherein the three-electrode system is inserted into a urine sample to be tested; The SWV waveform generating module comprises a square wave generating circuit, a step wave generating circuit, a voltage divider, a voltage bias circuit, a bus switch and a constant potential circuit, wherein the square wave generating circuit is used to generate square wave waveforms Vy and Vx, Vx is input to the input end of the step wave generating circuit, and Vy is input to the input end of the voltage divider; the step wave generating circuit feeds back a signal Vz to the square wave generating circuit, and outputs a step wave Vin1 to the bus switch; the voltage divider outputs a square wave Vin2 to the bus switch; the voltage bias circuit outputs a DC voltage Vin3, the bus switch is coupled to the constant potential circuit, and outputs voltage waveforms Vae and Vre, Vae is input to the auxiliary electrode, Vre is input to the reference electrode, and the working electrode outputs a detection result current Iwe; A current detection circuit is coupled to the output terminal of the working electrode and outputs a voltage signal Vsig after current-voltage conversion; A low-pass filter circuit is coupled to the output end of the current detection circuit and outputs a voltage signal Vout after noise reduction; ADC, coupled to the output end of the low-pass filter circuit, outputting a digital signal; FPGA, coupled to the output end of the ADC, the FPGA controls the selective conduction of the step wave generating circuit and the bus switch, and generates a current-voltage conversion amplification factor signal of the current detection circuit; A display is coupled to the FPGA, and is used to display the detection results and operating status and serve as a control interface.

2. The electrochemical detection system for early gastric cancer markers in human urine according to claim 1, characterized in that: The square wave generating circuit includes two feedback networks. At the in-phase input end, resistors R1, R2 and the output end of the operational amplifier OP1 form positive feedback and output Vy; at the inverting input end, capacitor C1, resistor R3 and the output end of the operational amplifier OP1 form negative feedback and output Vx.

3. The electrochemical detection system for early gastric cancer markers in human urine according to claim 1, characterized in that: The step wave generating circuit comprises a differential circuit, a limiter circuit, an integration circuit and a voltage comparator connected in sequence, wherein: Vx obtains positive and negative pulse voltages through the differential circuit; After the positive and negative pulse voltages pass through the over-limiting circuit, only the positive pulse voltage remains; The integration circuit comprises a resistor R7, an operational amplifier OP2, an integration capacitor C3, a MOS tube M1 and a reset switch Srst, one end of the resistor R7 is connected to the limiter circuit, and the other end is respectively connected to the inverting input end of the operational amplifier OP2; the non-inverting input end of the operational amplifier OP2 is grounded; the integration capacitor C3, the reset switch Srst and the MOS tube M1 are respectively connected in parallel between the inverting input end and the output end of the operational amplifier OP2; The voltage comparator comprises an operational amplifier OP3, a resistor R9, a resistor R10 and a resistor R11, the output end of the operational amplifier OP2 is connected to the negative phase input end of the operational amplifier OP3; the positive phase input end of the operational amplifier OP3 is connected to the ground GND through the resistor R9 in one way, and is connected to the power supply VEE through the resistor R10 in another way, and the output end is connected to the MOS tube M1; the resistor R11 is connected between the positive phase input end and the output end of the operational amplifier OP3; the output end of the operational amplifier OP2 outputs a step wave Vin1; The FPGA controls the conduction of the reset switch Srst. When the reset switch Srst is closed, the integration capacitor C3 is discharged. When detection needs to start, the FPGA controls the reset switch Srst to be disconnected, so that the integration circuit starts integration and accumulation.

4. The electrochemical detection system for early gastric cancer markers in human urine according to claim 3, characterized in that: The output end of the operational amplifier OP3 is connected to the MOS transistor M1 through the diode D2, and the output end of the operational amplifier OP3 outputs a voltage Vz through the diode D3.

5. The electrochemical detection system for early gastric cancer markers in human urine according to claim 1, characterized in that: The voltage divider includes an operational amplifier OP4, an operational amplifier OP5, a capacitor C4, a capacitor C5, a resistor R12 and a resistor R13, wherein: The operational amplifier OP4 serves as a first voltage follower, and the operational amplifier OP5 serves as a second voltage follower; The positive phase input terminal of the operational amplifier OP4 inputs Vy, and the negative phase input terminal is connected to the output terminal. The output terminal of the operational amplifier OP4 is connected to the resistor R12. The resistor R12 and the resistor R13 are connected in series. The resistor R12, the resistor R13, the capacitor C4, and the capacitor C5 are connected in parallel. The resistor R13 and the capacitor C5 are connected to the ground GND via a wire. The resistor R12 and the resistor R13 are connected to the positive phase input terminal of the operational amplifier OP5 via a wire. The negative phase input terminal of the operational amplifier OP5 is connected to the output terminal. The output terminal of the operational amplifier OP5 outputs a square wave Vin2.

6. The electrochemical detection system for early gastric cancer markers in human urine according to claim 1, characterized in that: The voltage bias circuit includes a resistor R14, a resistor R15 and an operational amplifier OP6, one end of the resistor R14 is connected to the ground GND, and the other end is connected to the resistor R15, the resistor R15 is connected to the power supply VEE, a wire is led between the resistor R14 and the resistor R15 and connected to the positive input terminal of the operational amplifier OP6, the negative input terminal of the operational amplifier OP6 is connected to the output terminal, and the output terminal of the operational amplifier OP6 outputs a DC voltage Vin3.

7. The electrochemical detection system for early gastric cancer markers in human urine according to claim 1, characterized in that: The step wave Vin1 is converted into a square wave Vin1' through a bus switch, the square wave Vin2 is converted into a step wave Vin2' through a bus switch, and the DC voltage Vin3 is converted into a DC bias Vin3' through a bus switch; The constant potential circuit comprises a resistor R16, a resistor R17, a resistor R18, a resistor R19, a resistor R20, an operational amplifier OP7 and an operational amplifier OP8, the square wave Vin1' is input to one end of the resistor R16, the other end of the resistor R16 is connected to the resistor R19, the resistor R19 is grounded, and a wire is led out between the resistor R16 and the resistor R19 and connected to the positive phase input end of the operational amplifier OP7; the step wave Vin2' is input to one end of the resistor R17, the other end of the resistor R17 is connected to the negative phase input end of the operational amplifier OP7, and the output end of the operational amplifier OP7 outputs Vae; The DC bias Vin3' is input to one end of the resistor R18, and the resistor R18 and the resistor R20 are connected to the resistor R17 via a wire. The resistor R20 is connected to the negative input and output of the operational amplifier OP8, and Vre is input to the positive input of the operational amplifier OP8.

8. The electrochemical detection system for early gastric cancer markers in human urine according to claim 1, characterized in that: The current detection circuit includes an operational amplifier OP9, an operational amplifier OP10, a capacitor C6, a resistor R21, a resistor R22, a resistor R23, a resistor R24, a resistor R25, a resistor R26, a resistor R27 and a 4:1 multiplexer; The operational amplifier OP9, the capacitor C6, the resistor R21, the resistor R22, the resistor R23, the resistor R24 ​​and the 4:1 multiplexer form a current-to-voltage conversion circuit with variable gain, the positive input terminal of the operational amplifier OP9 is grounded, and the negative input terminal is connected in parallel to the input terminal of the 4:1 multiplexer through the resistor R21, the resistor R22, the resistor R23 and the resistor R24 ​​respectively, the detection result current Iw is input to the negative input terminal of the operational amplifier OP9, the capacitor C6 is connected in parallel between the negative input terminal and the output terminal of the operational amplifier OP9, the capacitor C6 is used as a voltage holding capacitor, and the 4:1 multiplexer selects the smallest resistor among the resistor R21, the resistor R22, the resistor R23 and the resistor R24 ​​by default to obtain the maximum current detection range; The output end of the operational amplifier OP9 is connected to the negative phase input end of the operational amplifier OP10 through the resistor R25, the positive phase input end of the operational amplifier OP10 is grounded through the resistor R26, and the resistor R27 is connected in parallel between the negative phase input end and the output end of the operational amplifier OP10 to form a voltage amplification and inversion circuit.

9. The electrochemical detection system for early gastric cancer markers in human urine according to claim 1, characterized in that: The low-pass filter circuit includes a resistor R28, a resistor R29, a resistor R30, a resistor R31, a capacitor C7, a capacitor C8 and an operational amplifier OP11; The resistor R28 and the resistor R29 are connected in series and connected to the non-inverting input terminal of the operational amplifier OP11. The resistor R29 and the non-inverting input terminal of the operational amplifier OP11 are connected to the capacitor C8 via a wire and grounded. The resistor R28 and the resistor R29 are connected to the output terminal of the operational amplifier OP11 via the capacitor C7. One end of the resistor R30 is grounded, and the other end is connected to the negative input terminal of the operational amplifier OP11. The resistor R30 and the negative input terminal of the operational amplifier OP11 are connected to the output terminal of the operational amplifier OP11 via the resistor R31.

10. An electrochemical detection method for early gastric cancer markers in human urine, characterized in that: The method is implemented by using the electrochemical detection system for early gastric cancer markers in human urine according to any one of claims 1 to 9, the method comprising: Place the three-electrode system into the urine sample to be tested; FPGA controls the selective conduction of the SWV waveform generation module to generate the required SWV waveform; The FPGA controls the selective conduction of the bus switch to apply the required SWV waveform to the three-electrode system; The FPGA-controlled current detection circuit automatically adapts the amplification factor of the current-voltage conversion according to the detection result current of the three-electrode system; When the waveform is applied for a preset number of times, the detection is stopped and the detection signal waveform is stored in the FPGA. After FPGA data processing, the test result of the gastric cancer marker concentration in the urine sample is output.

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