Three-electrode electrochemical marker sensing system and method

Abstract

The present application relates to the field of electrochemical detection and biosensing technology, in particular to a three-electrode electrochemical marker sensing system and method. The system comprises a constant potential module, an excitation voltage module, an IV conversion module and a signal conditioning module. The constant potential module adopts a first operational amplifier to form a voltage follower, locking the potential of the reference electrode and the working electrode; the excitation voltage module adopts a second operational amplifier to form a voltage follower, setting the potential of the counter electrode as an external excitation signal, forming a controllable potential difference with the working electrode to drive the measured object to generate an oxidation-reduction reaction; the IV conversion module linearly converts the weak current of the working electrode into an initial voltage through a third operational amplifier and a feedback resistor; the signal conditioning module adopts a fourth operational amplifier and a resistance-capacitance to form a second-order active low-pass filter, and outputs a high signal-to-noise ratio signal after noise reduction and buffering. The present application adopts an independent following and driving architecture, has fast dynamic response and strong anti-interference, and can realize accurate detection of picoampere-level current.

Description

Technical Field

[0001] This invention relates to the fields of electrochemical detection and biosensing technology, specifically to a three-electrode electrochemical biomarker sensing system and method. Background Technology

[0002] With the rapid development of biomedical electronics and microanalysis technologies, real-time monitoring of chemical biomarkers in and on the human body has become a core requirement for precision medicine and daily health management. Currently, there are various methods for detecting chemical biomarkers, including ion-sensitive field-effect transistors (FETs) and surface plasmon resonance (SPR) detection. While FET solutions are easy to miniaturize, they often face challenges such as threshold voltage drift and weak environmental stability when handling complex physiological fluids. In contrast, the three-electrode detection system, due to its ability to generate a potential difference that induces redox reactions by constructing a constant potential system using a reference electrode, and its ability to accurately capture weak redox currents using a circuit formed by the counter electrode and the working electrode, exhibits significant advantages in terms of sensitivity, selectivity, and repeatability in quantitative analysis, making it the preferred solution in the field of biochemical sensing.

[0003] Currently, in simple two-electrode systems, a loop is formed by the working electrode and the counter electrode or reference electrode. The detection principle relies on the voltage difference between the two electrodes to directly drive the reaction. However, since the loop current must flow through the counter electrode, which also functions as a reference, this causes severe polarization shift in the electrode, resulting in a significant drift of the reference potential as the reaction proceeds, which cannot meet the requirements of high-precision quantitative analysis. In contrast, the traditional three-electrode principle introduces an independent reference electrode to monitor the potential and uses the counter electrode to compensate for the current, thus solving the polarization problem. However, most existing portable three-electrode circuits follow the nested closed-loop feedback architecture of desktop workstations. They use operational amplifiers to form complex dynamic compensation loops, which not only leads to severe wiring redundancy on the substrate, but also, in a single-power supply environment, if the working electrode is directly grounded, the high-potential reaction can easily cause signal truncation.

[0004] This invention overcomes the limitations of both of the aforementioned systems by reconstructing the underlying logic. Compared to the two-electrode system, this invention achieves "non-destructive sampling" and strong locking of the reference electrode potential through a constant potential module, ensuring absolute accuracy of the reaction driving force. Compared to the traditional nested three-electrode circuit, this invention abandons complex loop compensation logic and adopts independent follower driving logic to replace the traditional nested closed-loop logic: by decoupling the constant potential module from the excitation voltage module, independent voltage followers are used to lock the reference reference and excitation source respectively, effectively avoiding the risk of self-excited oscillation that is prone to occur under large impedance fluctuations in traditional closed-loop circuits. This invention also creatively locks the reference electrode potential and the bias voltage of the IV conversion module precisely to the same reference reference, constructing a zero-point balance system at the physical level. This design not only eliminates the potential drift problem of the two-electrode system, but also solves the bottleneck of complex wiring and easy distortion in the traditional three-electrode architecture. It truly realizes highly integrated, adhesive, and portable in-situ monitoring that can be performed without an electrochemical workstation. Summary of the Invention

[0005] This invention provides a three-electrode electrochemical biomarker sensing system and method to solve the technical problems of existing detection devices being bulky and unable to be attached to the surface of organisms.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: A three-electrode electrochemical biomarker sensing system includes a potentiostatic module, an excitation voltage module, an IV conversion module, and a signal conditioning module. The non-inverting input of the potentiostatic module is connected to a reference voltage, and its output is connected to a reference electrode. The non-inverting input of the excitation voltage module is connected to an excitation voltage, and its output is connected to a counter electrode. The inverting input of the IV conversion module is connected to a working electrode, and its non-inverting input is connected to a bias voltage. Its output is connected to the input of the signal conditioning module. The reference electrode, working electrode, and counter electrode together form a three-electrode electrochemical detection circuit, electrically connecting the potentiostatic module, excitation voltage module, and IV conversion module. The constant potential module is used to lock the potential of the bias voltage connected to the IV conversion module and the reference voltage to the same reference potential. The excitation voltage module is used to output an excitation voltage signal to the counter electrode. The three-electrode electrochemical detection circuit generates a potential difference based on the bias voltage of the IV conversion module and the excitation voltage signal. The analyte reacts under the drive of the potential difference, forming a redox current flowing from the working electrode to the counter electrode. The IV conversion module is used to capture the redox current generated by the reaction of the analyte through the working electrode and linearly map the redox current into an initial voltage signal. The signal conditioning module is used to perform signal noise reduction and smoothing on the initial voltage signal, output an output voltage that reflects the concentration of the biomarker, and use a fitting algorithm to process the output voltage to obtain the biomarker concentration.

[0007] The constant potential module includes a first integrated operational amplifier TIA1. The non-inverting input of the first integrated operational amplifier TIA1 is connected to a reference voltage Vref. The inverting input and output of the first integrated operational amplifier TIA1 are electrically connected to form a voltage follower structure. The output of the first integrated operational amplifier TIA1 is electrically connected to a reference electrode REF. The constant potential module locks the bias voltage connected to the IV conversion module and the reference voltage to the same reference potential through the first integrated operational amplifier TIA1.

[0008] The excitation voltage module includes a second integrated operational amplifier TIA2, and the non-inverting input of the second integrated operational amplifier TIA2 is connected to the excitation voltage signal. The inverting input and output of the second integrated operational amplifier TIA2 are electrically connected via a feedback path to form a voltage follower structure. The output of the second integrated operational amplifier TIA2 is connected to the counter electrode CE. The second integrated operational amplifier TIA2 transmits the excitation voltage signal. This is transmitted to the counter electrode CE to dynamically adjust the output level of the counter electrode CE according to the excitation voltage signal. To form a stable potential difference with millivolt-level precision .

[0009] The IV conversion module is electrically connected to the working electrode WE. The IV conversion module includes a third integrated operational amplifier TIA3 and an adjustable feedback resistor network Rx. The inverting input terminal of the third integrated operational amplifier TIA3 is connected to the working electrode WE, and the non-inverting input terminal of the third integrated operational amplifier TIA3 is connected to the same bias voltage as the reference point of the constant potential module. The feedback resistor network Rx is connected between the output terminal and the inverting input terminal of the third integrated operational amplifier TIA3.

[0010] The adjustable feedback resistor network Rx includes an analog multiplexer U19 and an eight-channel feedback resistor array. The common drain pin of the analog multiplexer U19 is connected to the output of the third integrated operational amplifier TIA3. The eight source channel pins S1 to S8 of the analog multiplexer U19 are electrically connected to one end of the eight feedback resistors respectively. The other ends of the eight feedback resistors converge and are electrically connected to the inverting input of the third integrated operational amplifier TIA3.

[0011] The signal conditioning module is connected to the output of the IV conversion module. The signal conditioning module includes a fourth integrated operational amplifier TIA4 and a second-order active low-pass filter network composed of a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2. One end of the first resistor R1 serves as the signal input terminal and is electrically connected to the output of the IV conversion module. The other end of the first resistor R1 is connected in series with the second resistor R2. The connection node of the first resistor R1 and the second resistor R2 is connected to one end of the second capacitor C2. The other end of the second capacitor C2 is grounded. The other end of the second resistor R2 is electrically connected to the non-inverting input terminal of the fourth integrated operational amplifier TIA4. The inverting input terminal and the output terminal of the fourth integrated operational amplifier TIA4 are electrically connected. The first capacitor C1 is connected across the connection node of the first resistor R1 and the second resistor R2 and the output terminal of the fourth integrated operational amplifier TIA4. The output terminal of the fourth integrated operational amplifier TIA4 serves as the output terminal of the signal conditioning module and is used to output the processed output voltage reflecting the concentration of the marker.

[0012] A method for operating a three-electrode electrochemical biomarker sensing system includes the following steps: The non-inverting input of the IV conversion module is connected to the bias voltage VCC2, and the non-inverting input of the first integrated operational amplifier TIA1 of the constant potential module receives the reference voltage Vref. The first integrated operational amplifier TIA1 locks the bias voltage VCC2 and the reference voltage Vref to the same reference potential. The excitation voltage signal is connected to the non-inverting input of the second integrated operational amplifier TIA2 of the excitation voltage module. The signal is input to the counter electrode, and the three-electrode electrochemical detection circuit uses the bias voltage VCC2 from the IV conversion module and the excitation voltage signal. A potential difference is generated. The biomarker to be tested reacts at this potential difference Driven by this process, a redox current is generated flowing from the working electrode to the counter electrode. ; The IV conversion module includes a third integrated operational amplifier TIA3 and an adjustable feedback resistor network Rx. The non-inverting input of the third integrated operational amplifier TIA3 is connected to a bias voltage VCC2, which is the same as the potential reference voltage, and captures the redox current generated by the reaction of the analyte through the working electrode. Based on the redox current generated by the reaction of the marker to be tested The strength is adaptively adjusted to adjust the transimpedance gain, linearly mapping weak currents ranging from nanoamperes to microamperes to an initial voltage signal. ; The signal conditioning module receives the initial voltage signal. For the initial voltage signal Noise reduction processing is performed, and the initial voltage signal is also processed. By limiting the rate of signal change and eliminating spikes and glitches caused by human movement or unstable contact, the final output voltage has a high signal-to-noise ratio and is stable, reflecting the true concentration of the biomarker. The output voltage was analyzed using a fitting algorithm. Processing was performed to obtain the concentration of the biomarker. .

[0013] The initial voltage signal Noise reduction processing is performed, specifically for the initial voltage signal. Through the path formed by the first resistor R1 and the second capacitor C2, the discharge function of the second capacitor C2 on the high-frequency signal is utilized to achieve the initial signal... Primary noise filtering; then the initial signal after primary noise filtering. The signal is input to the non-inverting input of the fourth integrated operational amplifier TIA4 via the second resistor R2, and a positive feedback mechanism is introduced by the first capacitor C1 connected between the output terminal and the RC connection node, which generates a steep attenuation slope and achieves precise removal of high-frequency noise.

[0014] Obtain a stable output voltage with a high signal-to-noise ratio that reflects the true concentration of the biomarker. Afterwards, the output voltage needs to be amplified using the inverse transimpedance amplification principle and circuit parameters. Reduced to the original redox current The formula for calculating the reverse transimpedance amplification principle is as follows:

[0015] In the formula: This is the bias voltage; The selected feedback resistor value for the current microprocessor.

[0016] The output voltage is obtained by using a fitting algorithm. Processing was performed to obtain the concentration of the biomarker. The calculation formula is: .

[0017] Compared with the prior art, the present invention has the following beneficial effects: This invention, while ensuring millivolt-level detection accuracy and long-term signal stability, abandons the traditional nested closed-loop feedback and improves upon it with an independent follower-driven architecture and introduces reference alignment logic. The potential control logic, originally reliant on large terminals, is restructured into a lightweight hardware module, greatly simplifying wiring redundancy and device size. It adopts an independent follower-driven and reference-aligned technical approach. The constant potential module utilizes the high impedance characteristics of the first integrated operational amplifier to precisely lock the reference electrode potential at the reference level and strictly align it with the bias voltage of the IV conversion module, constructing a zero-bias balance system at the physical level and eliminating static drift. The excitation voltage module independently drives the counter electrode to generate a controlled excitation field Vin, inducing a precise biochemical reaction current. Combined with a second-order active filter network formed by the signal conditioning module, the system can deeply filter out environmental noise and dynamic glitches, ensuring accurate mapping from weak biochemical signals to stable voltage signals.

[0018] Unlike the complex nested closed-loop feedback architecture commonly used in traditional electrochemical workstations, this invention avoids the risk of self-oscillation that traditional loops are prone to when solution impedance fluctuates drastically by decoupling the excitation and sampling logic. Compared to the expensive and bulky potentiometer controllers of benchtop devices, this invention utilizes simple voltage-following logic and an adaptive feedback resistor network to achieve effective control and current capture of the redox process. This architectural optimization allows the circuit to break free from dependence on large electrochemical workstations, significantly reducing hardware size and power consumption, thus enabling high-precision biochemical analysis functions to evolve from detectors to wearable flexible sensing devices. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of a three-electrode electrochemical biomarker sensing system module in an embodiment of the present invention; Figure 2 This is a schematic diagram of the circuit structure of a three-electrode electrochemical biomarker sensing system in an embodiment of the present invention; Figure 3 This is a schematic diagram of the circuit structure of the dynamically switching resistor array Rx in a three-electrode electrochemical biomarker sensing system according to an embodiment of the present invention. Detailed Implementation

[0020] To further understand the content of this invention, the invention will be described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the embodiments are merely illustrative and not limiting of the invention.

[0021] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0022] Example 1 This embodiment proposes a three-electrode electrochemical biomarker sensing system, such as Figure 1As shown, the system includes a constant potential module, an excitation voltage module, an IV conversion module, and a signal conditioning module. The non-inverting input of the constant potential module is connected to a reference voltage, and its output is connected to a reference electrode. The non-inverting input of the excitation voltage module is connected to an excitation voltage, and its output is connected to a counter electrode. The inverting input of the IV conversion module is connected to a working electrode, and the non-inverting input of the IV conversion module is connected to a bias voltage. Its output is connected to the input of the signal conditioning module. The reference electrode, working electrode, and counter electrode together form a three-electrode electrochemical detection circuit, electrically connecting the constant potential module, the excitation voltage module, and the IV conversion module. The constant potential module is used to lock the potential of the bias voltage connected to the IV conversion module and the reference voltage to the same reference potential. The excitation voltage module is used to output an excitation voltage signal to the counter electrode. The three-electrode electrochemical detection circuit generates a potential difference based on the bias voltage of the IV conversion module and the excitation voltage signal. The analyte reacts under the drive of the potential difference, forming a redox current flowing from the working electrode to the counter electrode. The IV conversion module is used to capture the redox current generated by the reaction of the analyte through the working electrode and linearly map the redox current into an initial voltage signal. The signal conditioning module is used to perform signal noise reduction and smoothing on the initial voltage signal, output an output voltage that reflects the concentration of the biomarker, and use a fitting algorithm to process the output voltage to obtain the biomarker concentration.

[0023] Example 2 Based on the three-electrode electrochemical biomarker sensing system proposed in Example 1, this example provides an attachable three-electrode electrochemical biomarker sensing circuit based on a flexible substrate, such as... Figure 1-3 As shown, the system includes a constant potential module, an excitation voltage module, an IV conversion module, and a signal conditioning module. By combining an independent voltage follower drive architecture with 1.65V reference alignment logic, precise locking of the reference potential and working electrode potential is achieved, eliminating system static bias and significantly improving the control accuracy of the electrochemical reaction potential and the stability of signal detection. An adaptive range switching network composed of a high-precision feedback resistor array enhances the circuit's sensitivity to capturing signals from different concentrations of biomarkers and effectively prevents signal saturation. Through the deep integration of a second-order active low-pass filter topology and flexible substrate technology, high-steepness noise attenuation and transient glitch smoothing are achieved, while giving the device excellent conformal application capabilities. This completely eliminates the reliance on bulky detection terminals and meets the needs for portable, stable, and high signal-to-noise ratio monitoring in complex physiological environments such as motion monitoring and home care.

[0024] Specifically, such as Figure 2As shown, the constant potential module and the excitation voltage module adopt an independent driving architecture to establish a stable electrochemical reaction environment. The constant potential module includes a first integrated operational amplifier TIA1, which is configured as a voltage follower. Specifically, the non-inverting input terminal of the first integrated operational amplifier TIA1 is connected to a 1.65V reference voltage Vref, the inverting input terminal of the first integrated operational amplifier TIA1 is electrically connected to its output terminal to form a voltage follower structure, and the output terminal of the first integrated operational amplifier TIA1 is electrically connected to the reference electrode REF. The first integrated operational amplifier TIA1 utilizes its near-infinite input impedance to anchor the reference electrode REF, ensuring that no current is drawn from the reference electrode REF during the entire detection process, thus avoiding electrode polarization errors and enabling the reference electrode REF to obtain a high-precision electrochemical signal. Simultaneously, due to its voltage following function, the first integrated operational amplifier TIA1 forces the potential of the reference electrode REF to be locked at 1.65V, the same as the reference voltage Vref, making it highly consistent with the bias reference of the subsequent working electrode WE. This ensures that the bias voltage connected to the IV conversion module is locked at the same reference potential as the reference voltage, forming a system-level zero-point balance system and maintaining the chemical stability of the reference reference.

[0025] The excitation voltage module includes a second integrated operational amplifier TIA2, which is configured as a voltage follower. Specifically, the excitation voltage signal is connected to the non-inverting input of the second integrated operational amplifier TIA2. The inverting input and output of the second integrated operational amplifier TIA2 are electrically connected via a feedback path, forming a voltage follower structure. The output of the second integrated operational amplifier TIA2 is connected to the counter electrode CE. The second integrated operational amplifier TIA2 serves as an independent power source for the system, capable of transmitting the excitation voltage signal... The signal is transmitted to the counter electrode CE and is based on the excitation voltage signal. The output level of the counter electrode (CE) is dynamically adjusted. The reference electrode, working electrode, and counter electrode together constitute a three-electrode electrochemical detection circuit. The three-electrode electrochemical detection circuit is based on the bias voltage of 1.65V between the counter electrode (CE) and the working electrode (WE) after being locked at the potential by the constant potential module, and the excitation voltage signal. Between them, a potential difference is forced to remain stable with millivolt-level precision. The potential difference From excitation voltage signal As determined by the instructions, it can be stably controlled within a millivolt-level precision range, thereby inducing precise and controllable redox reactions in the analyte within the electrolytic system. Compared to traditional closed-loop feedback, this independent follower drive architecture provides the excitation voltage module in this embodiment with better dynamic response speed and system stability.

[0026] The potential difference Driven by this process, an oxidation reaction occurs at the working electrode WE, generating directionally moving electrons. This results in a redox current flowing from the working electrode WE to the counter electrode CE in the solution system of the analyte. The redox current The intensity of the assay is linearly proportional to the concentration of the assay solution.

[0027] The IV conversion module includes a third integrated operational amplifier TIA3 and an adjustable feedback resistor network Rx. The inverting input of the third integrated operational amplifier TIA3 is electrically connected to the working electrode WE, and the non-inverting input of the third integrated operational amplifier TIA3 is connected to a bias voltage VCC2, which is the same as the potential reference voltage, and captures the redox current through the working electrode WE. The inverting input of the third integrated operational amplifier TIA3 is connected to the working electrode WE, and the non-inverting input is connected to a 1.65V bias voltage VCC2. This bias voltage VCC2 is consistent with the reference reference of the constant potential module. This virtual ground bias design ensures that the circuit has complete bidirectional current detection capability in a 3.3V single power supply environment. A feedback resistor network Rx is connected between the output and inverting input of the third integrated operational amplifier TIA3, such as... Figure 3 As shown, the adjustable feedback resistor network Rx includes an analog multiplexer U19 and an eight-channel feedback resistor array. The common drain pin of the analog multiplexer U19 is connected to the output of the third integrated operational amplifier TIA3. The eight source channel pins S1 to S8 of the analog multiplexer U19 are electrically connected to one end of the eight feedback resistors, and the specific connection relationship and resistance value settings are as follows: Pin S1 is connected to the tenth resistor R10, which has a resistance of 50Ω; Pin S2 is connected to the eleventh resistor R11, which has a resistance of 300Ω. Pin S3 is connected to the twelfth resistor R12 with a resistance of 1kΩ. Pin S4 is connected to the thirteenth resistor R13, which has a resistance of 3kΩ. Pin S5 is connected to the fourteenth resistor R14, which has a resistance of 10kΩ. Pin S6 is connected to the fifteenth resistor R15, which has a resistance of 100kΩ. Pin S7 is connected to the sixteenth resistor R16, which has a resistance of 300kΩ. Pin S8 is connected to the seventeenth resistor R17 with a resistance of 1MΩ.

[0028] The other ends of the eight feedback resistors converge and are electrically connected to the inverting input of the third integrated operational amplifier TIA3. The microprocessor is connected to the address selection pins A0, A1, and A2 and the enable pin EN of the analog multiplexer U19 via a logic bus. It dynamically switches the resistance values ​​of the resistors connected to the feedback loop of the third integrated operational amplifier TIA3 by inputting specific binary code logic. Utilizing the transimpedance amplification principle, this network can detect the current generated by the reaction of the measured marker. The strength is adaptively adjusted to adjust the transimpedance gain, linearly mapping weak currents ranging from nanoamperes to microamperes to an initial voltage signal. This refined range switching logic ensures that the system maintains optimal detection sensitivity even when the biomarker concentration fluctuates drastically, and effectively prevents output signal saturation due to excessive feedback resistance, thereby achieving high-precision linear monitoring across the entire range.

[0029] The signal conditioning module is connected to the output of the IV conversion module and is used to reduce noise in the initial voltage. The signal conditioning module includes a fourth integrated operational amplifier TIA4 and a second-order active low-pass filter network consisting of a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2. One end of the first resistor R1 serves as the signal input terminal and is electrically connected to the output of the IV conversion module to receive the initial voltage signal. The other end of the first resistor R1 is connected in series with the second resistor R2. The connection point of the first resistor R1 and the second resistor R2 is connected to one end of the second capacitor C2, forming an RC connection point. The other end of the second capacitor C2 is grounded, forming a ground branch. The other end of the second resistor R2 is electrically connected to the non-inverting input of the fourth integrated operational amplifier TIA4. The inverting input and output of the fourth integrated operational amplifier TIA4 are electrically connected. The first capacitor C1 is connected across the RC connection point and the output of the fourth integrated operational amplifier TIA4. The output of the fourth integrated operational amplifier TIA4 serves as the output of the signal conditioning module, used to output the processed voltage signal. .

[0030] Initial voltage signal Through the path formed by the first resistor R1 and the second capacitor C2, the discharge function of the second capacitor C2 on high-frequency signals is used to achieve the initial voltage signal. Primary noise filtering; then the initial voltage signal after primary noise filtering. The signal is input to the non-inverting input of the fourth integrated operational amplifier TIA4 via the second resistor R2. A positive feedback mechanism is introduced through the first capacitor C1 connected between the output and the RC connection node, generating a steep attenuation slope to precisely remove high-frequency noise. Simultaneously, the signal conditioning RC network, composed of the first resistor R1, the second resistor R2, the first capacitor C1, and the second capacitor C2, utilizes the integral energy storage characteristics of the signal conditioning RC network to limit the rate of signal change, effectively eliminating spikes caused by human movement or unstable contact. The fourth integrated operational amplifier TIA4 is configured with a non-inverting buffer structure, utilizing its high input impedance to protect the filter network parameters and its extremely low output impedance to significantly enhance signal driving capability, ultimately outputting a high signal-to-noise ratio stable voltage that reflects the true concentration of the marker. .

[0031] To obtain a pure output voltage Then, through the principle of reverse transimpedance amplification, the circuit parameters are converted to output voltage. Reduced to the original redox current The formula for calculating the reverse transimpedance amplification principle is as follows:

[0032] In the formula: A virtual ground bias reference of 1.65V; The selected feedback resistor value for the current microprocessor; by reading the output voltage. The difference between this voltage and the virtual ground bias reference voltage of 1.65V allows for the precise calculation of the nanoampere-level redox current generated by the sensor. At constant potential Driven by this process, the reaction on the surface of the working electrode WE follows the Cotterell equation or its modified form.

[0033] In a diffusion-controlled electrochemical system, the generated redox current There is a strict proportional relationship between the reactant concentration C and the reactant concentration C: Where n is the total number of electrons transferred in the redox reaction; F is the Faraday constant; A is the effective surface area of ​​the working electrode; D is the diffusion coefficient of the analyte in the solution; t is the time for the electrochemical reaction to occur; and π is the constant of pi. This can be simplified to form a linear model for engineering applications: Where C is the concentration of the analyte; K is the sensitivity coefficient, representing the change in current caused by a unit change in concentration; and b is the background current or noise floor.

[0034] Before practical application, standard curves for voltage and concentration were established experimentally. Using this three-electrode electrochemical biomarker sensing circuit, a series of biomarker solutions with known standard concentrations were measured, and the output voltage corresponding to each concentration was recorded. The stable value is obtained by using a fitting algorithm to determine the output voltage. After processing, a mathematical model is obtained: Ultimately, the microprocessor integrated into the flexible system acquires the output voltage at high frequency via a built-in analog-to-digital converter. The voltage value. Based on the currently active feedback resistor Rx setting, and substituting the preset calibration parameter K, the real-time concentration C is calculated.

[0035] Example 3 The three-electrode electrochemical biomarker sensing circuit described in Example 2 is integrated onto a flexible circuit board (FPC) with a thickness of less than 1 mm. The entire circuit is arranged using micro-sized packaged components. By integrating the three-electrode electrochemical biomarker sensing circuit in situ at the attachment location, the transmission distance of weak signals can be significantly shortened, external electromagnetic crosstalk caused by long wiring can be eliminated, and portable and accurate monitoring of physiological indicators can be achieved in dynamic environments.

[0036] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A three-electrode electrochemical biomarker sensing system, characterized in that, It includes a constant potential module, an excitation voltage module, an IV conversion module, and a signal conditioning module. The non-inverting input of the constant potential module is connected to a reference voltage, and the output of the constant potential module is connected to a reference electrode. The non-inverting input of the excitation voltage module is connected to an excitation voltage, and the output of the excitation voltage module is connected to a counter electrode. The inverting input of the IV conversion module is connected to the working electrode, the non-inverting input of the IV conversion module is connected to the bias voltage, and the output of the IV conversion module is connected to the input of the signal conditioning module. The reference electrode, working electrode, and counter electrode together form a three-electrode electrochemical detection circuit, which makes the constant potential module, excitation voltage module and IV conversion module electrically connected. The constant potential module is used to lock the potential of the bias voltage connected to the IV conversion module and the reference voltage to the same reference potential. The excitation voltage module is used to output an excitation voltage signal to the counter electrode. The three-electrode electrochemical detection circuit generates a potential difference based on the bias voltage of the IV conversion module and the excitation voltage signal. The analyte reacts under the drive of the potential difference, forming a redox current flowing from the working electrode to the counter electrode. The IV conversion module is used to capture the redox current generated by the reaction of the analyte through the working electrode and map the redox current into an initial voltage signal. The signal conditioning module is used to perform signal noise reduction and smoothing on the initial voltage signal, output an output voltage that reflects the concentration of the biomarker, and use a nonlinear fitting algorithm to process the output voltage to obtain the biomarker concentration.

2. The three-electrode electrochemical marker sensing system according to claim 1, characterized in that, The constant potential module includes a first integrated operational amplifier TIA1. The non-inverting input of the first integrated operational amplifier TIA1 is connected to a reference voltage Vref. The inverting input and output of the first integrated operational amplifier TIA1 are electrically connected to form a voltage follower structure. The output of the first integrated operational amplifier TIA1 is electrically connected to a reference electrode REF. The constant potential module locks the bias voltage connected to the IV conversion module and the reference voltage to the same reference potential through the first integrated operational amplifier TIA1.

3. The three-electrode electrochemical marker sensing system according to claim 1, characterized in that, The excitation voltage module includes a second integrated operational amplifier TIA2, and the non-inverting input of the second integrated operational amplifier TIA2 is connected to the excitation voltage signal. The inverting input and output of the second integrated operational amplifier TIA2 are electrically connected via a feedback path to form a voltage follower structure. The output of the second integrated operational amplifier TIA2 is connected to the counter electrode CE. The second integrated operational amplifier TIA2 transmits the excitation voltage signal. This is transmitted to the counter electrode CE to dynamically adjust the output voltage of the counter electrode CE according to the excitation voltage signal. To form a stable potential difference with millivolt-level precision .

4. The three-electrode electrochemical marker sensing system according to claim 1, characterized in that, The IV conversion module is electrically connected to the working electrode WE. The IV conversion module includes a third integrated operational amplifier TIA3 and an adjustable feedback resistor network Rx. The inverting input terminal of the third integrated operational amplifier TIA3 is connected to the working electrode WE, and the non-inverting input terminal of the third integrated operational amplifier TIA3 is connected to the same bias voltage as the reference point of the constant potential module. The feedback resistor network Rx is connected between the output terminal and the inverting input terminal of the third integrated operational amplifier TIA3.

5. The three-electrode electrochemical marker sensing system according to claim 4, characterized in that, The adjustable feedback resistor network Rx includes an analog multiplexer U19 and an eight-channel feedback resistor array. The common drain pin of the analog multiplexer U19 is connected to the output of the third integrated operational amplifier TIA3. The eight source channel pins S1 to S8 of the analog multiplexer U19 are electrically connected to one end of the eight feedback resistors respectively. The other ends of the eight feedback resistors converge and are electrically connected to the inverting input of the third integrated operational amplifier TIA3.

6. The three-electrode electrochemical marker sensing system according to claim 1, characterized in that, The signal conditioning module is connected to the output of the IV conversion module. The signal conditioning module includes a fourth integrated operational amplifier TIA4 and a second-order active low-pass filter network composed of a first resistor R1, a second resistor R2, a first capacitor C1, and a second capacitor C2. One end of the first resistor R1 serves as the signal input terminal and is electrically connected to the output of the IV conversion module. The other end of the first resistor R1 is connected in series with the second resistor R2. The connection node of the first resistor R1 and the second resistor R2 is connected to one end of the second capacitor C2. The other end of the second capacitor C2 is grounded. The other end of the second resistor R2 is electrically connected to the non-inverting input terminal of the fourth integrated operational amplifier TIA4. The inverting input terminal and the output terminal of the fourth integrated operational amplifier TIA4 are electrically connected. The first capacitor C1 is connected across the connection node of the first resistor R1 and the second resistor R2 and the output terminal of the fourth integrated operational amplifier TIA4. The output terminal of the fourth integrated operational amplifier TIA4 serves as the output terminal of the signal conditioning module and is used to output the processed output voltage reflecting the concentration of the marker.

7. A method for operating a three-electrode electrochemical biomarker sensing system, based on any one of claims 1 to 6, characterized in that, Includes the following steps: The non-inverting input of the IV conversion module is connected to the bias voltage VCC2, and the non-inverting input of the first integrated operational amplifier TIA1 of the constant potential module receives the reference voltage Vref. The first integrated operational amplifier TIA1 locks the bias voltage VCC2 and the reference voltage Vref to the same reference potential. The excitation voltage signal is connected to the non-inverting input of the second integrated operational amplifier TIA2 of the excitation voltage module. The signal is input to the counter electrode, and the three-electrode electrochemical detection circuit uses the bias voltage VCC2 from the IV conversion module and the excitation voltage signal. This generates a potential difference. The biomarker to be tested reacts at this potential difference Driven by this process, a redox current is generated flowing from the working electrode to the counter electrode. ; The IV conversion module includes a third integrated operational amplifier TIA3 and an adjustable feedback resistor network Rx. The non-inverting input of the third integrated operational amplifier TIA3 is connected to a bias voltage VCC2, which is the same as the potential reference voltage, and captures the redox current generated by the reaction of the analyte through the working electrode. Based on the redox current generated by the reaction of the marker to be tested The strength is adaptively adjusted to adjust the transimpedance gain, linearly mapping weak currents ranging from nanoamperes to microamperes to an initial voltage signal. ; The signal conditioning module receives the initial voltage signal. For the initial voltage signal Noise reduction processing is performed, and the initial voltage signal is also processed. By limiting the rate of signal change and eliminating spikes and glitches caused by human movement or unstable contact, the final output voltage has a high signal-to-noise ratio and is stable, reflecting the true concentration of the biomarker. The output voltage is obtained by using a nonlinear fitting algorithm. Processing was performed to obtain the concentration of the biomarker. .

8. The operating method of a three-electrode electrochemical marker sensing system according to claim 7, characterized in that, The initial voltage signal Noise reduction processing is performed, specifically for the initial voltage signal. Through the path formed by the first resistor R1 and the second capacitor C2, the discharge function of the second capacitor C2 on the high-frequency signal is utilized to achieve the initial signal... Primary noise filtering; then the initial signal after primary noise filtering. The signal is input to the non-inverting input of the fourth integrated operational amplifier TIA4 via the second resistor R2, and a positive feedback mechanism is introduced by the first capacitor C1 connected between the output terminal and the RC connection node, which generates a steep attenuation slope and achieves precise removal of high-frequency noise.

9. The operating method of a three-electrode electrochemical marker sensing system according to claim 7, characterized in that, Obtain a stable output voltage with a high signal-to-noise ratio that reflects the true concentration of the biomarker. Afterwards, the output voltage needs to be amplified using the inverse transimpedance amplification principle and circuit parameters. Reduced to the original redox current The formula for calculating the reverse transimpedance amplification principle is as follows: In the formula: This is the bias voltage; The selected feedback resistor value for the current microprocessor.

10. The operating method of a three-electrode electrochemical marker sensing system according to claim 7, characterized in that, The output voltage is obtained by using a fitting algorithm. Processing was performed to obtain the concentration of the biomarker. The calculation formula is: ,in, This is the bias voltage.

Images