An electrochemical sensor control circuit and system

Abstract

The application discloses an electrochemical sensor control circuit and system. The control circuit comprises: a bias driving module electrically connected with a counter electrode and a reference electrode of an electrochemical sensor, used for outputting a driving signal to the counter electrode to maintain a constant potential difference between the reference electrode and a working electrode of the electrochemical sensor; a transimpedance amplifier module with an input end connected to the working electrode of the electrochemical sensor, used for converting a current signal generated by the working electrode into a voltage signal; a dynamic feedback module connected between the output end and the input end of the transimpedance amplifier module, used for switching the feedback impedance of the transimpedance amplifier module, so that the bias control circuit alternately works in a bias maintaining mode and a data acquisition mode; and an analog-to-digital converter with an input end connected to the output end of the transimpedance amplifier module, used for acquiring the voltage signal output by the transimpedance amplifier module in the data acquisition mode. The application can greatly improve the tolerance of the sensor to abnormal leakage.

Description

Technical Field

[0001] This invention belongs to the field of sensor signal processing technology, and more specifically, relates to an electrochemical sensor control circuit and system. Background Technology

[0002] An electrochemical sensor is a device that measures the concentration of a target substance by detecting the current signal generated by the redox reaction on the electrode surface. Due to its high sensitivity and selectivity, it is widely used in medical diagnostics (such as continuous glucose monitoring), environmental monitoring, and industrial safety. In these applications, especially battery-powered portable or wearable devices (such as continuous glucose monitors), extremely stringent requirements are placed on the power consumption, stability, and reliability of the sensor system.

[0003] A typical electrochemical sensor employs a three-electrode system, including a working electrode, a counter electrode, and a reference electrode. Its readout circuitry typically includes a potentiostat module and a transimpedance amplifier module. The potentiostat maintains a constant potential difference between the working and reference electrodes, providing a stable environment for the electrochemical reaction; the transimpedance amplifier linearly converts the current signal generated at the working electrode into a voltage signal that can be acquired. Some electrochemical sensors produce very weak current signals (nanoampere level), such as continuous glucose monitoring sensors.

[0004] In existing technologies, to detect weak sensor currents, the feedback resistor of a transimpedance amplifier typically needs to be set to a large value (e.g., 1MΩ to 20MΩ). However, this design has an inherent drawback: during actual sensor use, abnormal leakage current may be introduced onto the working electrode due to sweat, improper wearing, or other reasons. According to Ohm's law, even a leakage current of several hundred nanoamps flowing through a large-value feedback resistor will generate a voltage drop of several volts at the input of the transimpedance amplifier, easily leading to amplifier output saturation. Figure 3 As shown, if there is abnormal leakage at the input of the TIA (transimpedance amplifier), for a resistor R of 10MΩ... TIA A leakage current of approximately 200 nA passes through resistor R. TIAThis can cause amplifier 2 to saturate and fail to maintain the correct bias voltage. Assuming a bias voltage V2 of 1.5V and a power supply voltage of 3V, the output of amplifier 2 can fluctuate by a maximum of 1.5V. However, 10MΩ x 200nA = 2V, which is greater than 1.5V, exceeding the maximum swing of the TIA, causing amplifier saturation. Once the transimpedance amplifier saturates, the entire negative feedback loop of the potentiostat will be disrupted, and the sensor's operating bias voltage will become uncontrolled. This not only leads to severe distortion of the current measurement results, but more importantly, even if the abnormal leakage current disappears, it will take a long time (or even be impossible) for the sensor to recover from the abnormal bias state to a stable operating state. During this period, all measurement data will be unreliable, and in severe cases, it can cause permanent damage to the sensor.

[0005] Therefore, existing technologies, while pursuing high measurement sensitivity, sacrifice system robustness and reliability, making it difficult to meet the application requirements of continuous, long-term, and reliable monitoring. There is an urgent need for a new bias control method that can significantly improve the tolerance of electrochemical sensors to external interference (especially leakage current) while ensuring high-precision measurement, and achieve rapid recovery of the bias state. Summary of the Invention

[0006] The purpose of this invention is to propose an electrochemical sensor control circuit and system to solve the technical problems of existing electrochemical sensors being susceptible to leakage current interference due to the use of fixed large-value feedback resistors, resulting in bias instability, slow recovery, and poor reliability; and to achieve a significant improvement in the sensor's tolerance to abnormal leakage current, bias recovery speed, and overall reliability, while meeting the requirements of ultra-low power consumption.

[0007] To achieve the above objectives, in a first aspect, the present invention provides an electrochemical sensor bias control circuit, comprising:

[0008] The bias drive module is electrically connected to the counter electrode and the reference electrode of the electrochemical sensor and is used to output a drive signal to the counter electrode to maintain a constant potential difference between the reference electrode and the working electrode of the electrochemical sensor.

[0009] A transimpedance amplifier module, whose input terminal is connected to the working electrode of the electrochemical sensor, is used to convert the current signal generated by the working electrode into a voltage signal.

[0010] The dynamic feedback module is connected between the output and input terminals of the transimpedance amplifier module and is used to switch the feedback impedance of the transimpedance amplifier module, so that the bias control circuit alternately operates in bias maintenance mode and data acquisition mode.

[0011] An analog-to-digital converter, whose input is connected to the output of the transimpedance amplifier module, is used to acquire the voltage signal output by the transimpedance amplifier module in the data acquisition mode.

[0012] Optionally, the bias drive module includes:

[0013] A first amplifier has a non-inverting input terminal for receiving a first bias voltage, an inverting input terminal connected to the reference electrode of the electrochemical sensor, and an output terminal connected to the counter electrode of the electrochemical sensor.

[0014] Optionally, the transimpedance amplifier module includes:

[0015] Adjustable resistor and second amplifier;

[0016] One end of the adjustable resistor is connected to the working electrode, and the other end is connected to the inverting input terminal of the second amplifier and the first input terminal of the analog-to-digital converter, respectively.

[0017] The non-inverting input of the second amplifier is used to receive the second bias voltage, and its output and inverting input are connected to the dynamic feedback module.

[0018] Optionally, the dynamic feedback module includes:

[0019] First resistor, second resistor, capacitor, and switching assembly;

[0020] The first end of the first resistor is connected to the inverting input terminal of the second amplifier, and its second end is connected to the first end of the second resistor;

[0021] The second end of the second resistor is connected to the output terminal of the second amplifier and the second input terminal of the analog-to-digital converter, respectively.

[0022] The first end of the capacitor is connected to the inverting input of the second amplifier, and the second end is connected to the second input of the analog-to-digital converter.

[0023] The switching assembly is used to enable the bias control circuit to operate alternately in bias maintenance mode and data acquisition mode.

[0024] The resistance of the first resistor is less than the resistance of the second resistor.

[0025] Optionally, it also includes:

[0026] The timing control module has its output terminal electrically connected to the control terminal of the switching component, and is used to output periodic control signals to control the on and off of the switching component, so that the bias control circuit alternately operates in bias maintenance mode and data acquisition mode.

[0027] Optionally, the switching assembly includes:

[0028] A control switch, the first end of which is connected to the second end of the first resistor, and the second end of which is connected to the output terminal of the second amplifier.

[0029] Optionally, the switching assembly includes:

[0030] First control switch, second control switch, third control switch and fourth control switch;

[0031] The first end of the first control switch is connected to the second end of the first resistor, and the second end of the first control switch is connected to the output end of the second amplifier.

[0032] The first end of the second control switch is connected between the first resistor and the second resistor, and its second end is connected to the second end of the capacitor;

[0033] The first end of the third control switch is connected to the second end of the second resistor, and the second end of the third control switch is connected to the output end of the second amplifier.

[0034] The first end of the fourth control switch is connected to the second end of the second resistor, and its second end is connected to the second end of the capacitor.

[0035] Optionally, when the timing control module controls the control switch to close, the bias control circuit operates in bias sustain mode;

[0036] When the timing control module controls the control switch to be turned off, the bias control circuit operates in data acquisition mode.

[0037] Optionally, when the timing control module controls the first control switch to close, the second control switch to close, the third control switch to open, and the fourth control switch to open, the bias control circuit operates in bias sustain mode;

[0038] When the timing control module controls the first control switch to open, the second control switch to open, the third control switch to close, and the fourth control switch to close, the bias control circuit operates in data acquisition mode.

[0039] In a second aspect, the present invention provides an electrochemical sensor control system, including an electrochemical sensor and an electrochemical sensor bias control circuit as described in any of the first aspects.

[0040] The beneficial effects of this invention are as follows: By switching the feedback impedance of the transimpedance amplifier module to a low resistance value in bias sustain mode through the dynamic feedback module, the sensitivity of the transimpedance amplifier input to leakage current can be significantly reduced, effectively preventing amplifier saturation and bias loop collapse caused by abnormal leakage current, thereby greatly improving the anti-interference capability and robustness of the system in complex operating environments; By switching the feedback impedance to a high resistance value in data acquisition mode, the transimpedance amplifier module has a sufficiently high conversion gain for the weak current signal generated by the working electrode, thereby ensuring measurement accuracy and sensitivity; By keeping the bias control circuit in a low-gain, high-stability bias sustain mode for most of the time and switching to a high-gain data acquisition mode only for a very short time, not only can the sensor bias state recover quickly from transient interference, but the analog-to-digital converter can also work intermittently periodically, thereby significantly reducing the overall power consumption of the system, and finally achieving the synergy and unity of high stability, high accuracy and ultra-low power consumption in a single electrochemical sensor system.

[0041] The system of the present invention has other features and advantages that will be apparent from or will be set forth in detail in the accompanying drawings and following detailed description, which together serve to explain the particular principles of the invention. Attached Figure Description

[0042] The above and other objects, features and advantages of the present invention will become more apparent from the accompanying drawings, in which like reference numerals generally denote like parts.

[0043] Figure 1 A schematic diagram of an electrochemical sensor bias control circuit according to Embodiment 1 of the present invention is shown.

[0044] Figure 2 A schematic diagram of an electrochemical sensor bias control circuit according to Embodiment 2 of the present invention is shown.

[0045] Figure 3 A schematic diagram of a conventional electrochemical sensor bias control circuit according to the background art of the present invention is shown. Detailed Implementation

[0046] The invention will now be described in more detail with reference to the accompanying drawings. While preferred embodiments of the invention are shown in the drawings, it should be understood that the invention can be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that the invention will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art.

[0047] An electrochemical sensor bias control circuit according to the present invention includes:

[0048] The bias drive module is electrically connected to the counter electrode and the reference electrode of the electrochemical sensor and is used to output a drive signal to the counter electrode to maintain a constant potential difference between the reference electrode and the working electrode of the electrochemical sensor.

[0049] The transimpedance amplifier module, whose input is connected to the working electrode of the electrochemical sensor, is used to convert the current signal generated by the working electrode into a voltage signal.

[0050] The dynamic feedback module is connected between the output and input terminals of the transimpedance amplifier module. It is used to switch the feedback impedance of the transimpedance amplifier module, so that the bias control circuit alternately operates in bias maintenance mode and data acquisition mode.

[0051] An analog-to-digital converter, whose input is connected to the output of a transimpedance amplifier module, is used to acquire the voltage signal output by the transimpedance amplifier module in data acquisition mode.

[0052] Specifically, the bias drive module, as the core guarantee for the stable operation of the electrochemical sensor, establishes a direct electrical connection with the sensor's counter electrode and reference electrode. Its core function is to accurately output a controllable drive signal to the counter electrode and dynamically compensate for potential changes in the counter electrode through a real-time feedback adjustment mechanism. This strictly maintains the potential difference between the reference electrode and the working electrode at a constant level, providing the necessary conditions for stable and repeatable electrochemical reactions between the electrodes and avoiding signal distortion or abnormal sensor operation due to potential fluctuations. The input terminal of the transimpedance amplifier module is directly connected to the working electrode of the electrochemical sensor and is specifically designed to condition the weak 10nA~100nA current signal output by the sensor. Utilizing its high input impedance and low input bias current characteristics, it efficiently converts the weak current signal into a voltage signal with appropriate amplitude while suppressing background noise interference, providing a clear and reliable voltage signal source for subsequent signal acquisition and ensuring accuracy and stability during the signal conversion process. The dynamic feedback module is the core component for achieving intelligent tuning in this invention. It is integrated into the feedback loop of the transimpedance amplifier module and is essentially a controlled variable impedance network. Controlled by external or internal timing signals, this module dynamically switches its equivalent impedance value: in bias sustaining mode, it switches to a low impedance state, where the transimpedance amplifier gain is low, primarily providing a stable virtual ground reference for the working electrodes. This significantly enhances the tolerance of the entire bias loop to abnormal leakage current at the input, preventing amplifier saturation. In data acquisition mode, it switches to a high impedance state, where the transimpedance amplifier regains high gain, efficiently converting nanoamplitude sensor currents into voltage signals with sufficient amplitude. The input of the analog-to-digital converter is connected to the output of the transimpedance amplifier module. After the circuit switches to data acquisition mode, it promptly acquires the voltage signal converted by the transimpedance amplifier, converting the analog voltage signal into a digital signal for subsequent processing units to perform data analysis and output results. The acquisition process is precisely synchronized with the mode switching timing of the dynamic feedback module, ensuring data acquisition is completed at the optimal signal gain, guaranteeing the accuracy of the detection results. Through the periodic switching of the dynamic feedback module, cycling between the two states of "maintaining stable bias" and "performing high-precision measurement," a fundamental unity of high robustness, high sensitivity, and ultra-low power consumption is achieved.

[0053] In one example, the bias driver module includes:

[0054] A first amplifier has a non-inverting input terminal for receiving a first bias voltage, an inverting input terminal connected to the reference electrode of an electrochemical sensor, and an output terminal connected to the counter electrode of an electrochemical sensor.

[0055] Specifically, the bias drive module is implemented as a classic potentiostat circuit. Its core is an operational amplifier, the first amplifier, which is selected for its high stability and low noise to meet the high-precision bias voltage control requirements of the electrochemical sensor. The non-inverting input of the first amplifier is dedicated to receiving an externally supplied first bias voltage. This bias voltage is precisely calibrated, and its value is preset according to the operating characteristics of the electrochemical sensor (such as electrode material and electrolyte system), providing a reference for maintaining the potential difference between the sensor electrodes. The inverting input of the first amplifier is directly electrically connected to the reference electrode of the electrochemical sensor, enabling real-time acquisition of the reference electrode's potential signal and forming a closed-loop feedback. The output signal is dynamically adjusted through the amplifier's high-gain characteristics, thereby achieving real-time monitoring and compensation of the reference electrode potential. The output of the first amplifier is connected to the counter electrode of the electrochemical sensor, and the drive signal after feedback regulation is accurately output to the counter electrode. By changing the potential of the counter electrode, external interference (such as power fluctuations and changes in ambient temperature) and potential shifts generated during the operation of the sensor itself are offset. Ultimately, the potential difference between the reference electrode and the working electrode of the electrochemical sensor is strictly guaranteed to remain stable at a preset constant value. This lays the foundation for stable and repeatable electrochemical reactions on the electrode surface and avoids distortion of the sensor output signal or abnormal operation due to potential difference fluctuations. It is especially suitable for ultra-low power consumption applications with extremely high requirements for bias stability, such as continuous blood glucose monitoring.

[0056] In one example, the transimpedance amplifier module includes:

[0057] Adjustable resistor and second amplifier;

[0058] One end of the adjustable resistor is connected to the working electrode, and the other end is connected to the inverting input terminal of the second amplifier and the first input terminal of the analog-to-digital converter, respectively.

[0059] The non-inverting input of the second amplifier is used to receive the second bias voltage, and its output and inverting input are connected to the dynamic feedback module.

[0060] Specifically, the transimpedance amplifier module, as the core unit for converting weak current signals from the electrochemical sensor, mainly consists of an adjustable resistor and a second amplifier. These two components work together to achieve high-precision signal conditioning. One end of the adjustable resistor is directly connected to the working electrode of the electrochemical sensor, specifically for receiving the weak current signal output by the sensor. The other end forms two connections: one to the inverting input of the second amplifier, providing a signal input path for the amplifier; the other to the first input of the analog-to-digital converter (ADC), providing a direct signal acquisition path for the ADC under specific operating conditions and improving the flexibility of the circuit layout. The second amplifier uses a low-noise, high-input-impedance operational amplifier to meet the conversion requirements of weak current signals. Its non-inverting input is specifically used to receive a second bias voltage, which is precisely calibrated and works in conjunction with the first bias voltage to ensure that the second amplifier operates at its optimal static operating point, avoiding signal distortion or decreased amplification efficiency due to operating point deviation. The output and inverting input of the second amplifier are connected to the dynamic feedback module to form a closed-loop feedback circuit. The dynamic feedback module flexibly switches the feedback impedance to adjust the gain characteristics of the second amplifier. In bias sustain mode, it uses a small feedback impedance to avoid amplifier saturation, and in data acquisition mode, it uses a large feedback impedance to achieve high-gain conversion of weak current. Finally, it stably and accurately converts the weak current signal generated by the working electrode into a voltage signal with appropriate amplitude, which not only meets the acquisition requirements of the analog-to-digital converter, but also ensures the stability and reliability of the signal conversion process. It is suitable for ultra-low power consumption and high-precision application scenarios such as continuous blood glucose monitoring.

[0061] In one example, the dynamic feedback module includes:

[0062] First resistor, second resistor, capacitor, and switching assembly;

[0063] The first end of the first resistor is connected to the inverting input of the second amplifier, and its second end is connected to the first end of the second resistor.

[0064] The second end of the second resistor is connected to the output of the second amplifier and the second input of the analog-to-digital converter, respectively.

[0065] The first end of the capacitor is connected to the inverting input of the second amplifier, and the second end is connected to the second input of the analog-to-digital converter.

[0066] The switching assembly is used to enable the bias control circuit to operate alternately in bias sustain mode and data acquisition mode;

[0067] The resistance of the first resistor is less than that of the second resistor.

[0068] Specifically, the dynamic feedback module, as the core functional unit for the bias control circuit to achieve dual-mode switching, is composed of a first resistor, a second resistor, a capacitor, and a switching component. Through precise circuit connections and timing control, it flexibly adjusts the feedback impedance characteristics of the transimpedance amplifier module. The first end of the first resistor is directly connected to the inverting input of the second amplifier, forming the starting node of signal feedback. Its second end is closely connected to the first end of the second resistor, and the two are connected in series to form the core feedback impedance network. The resistance value of the first resistor is smaller than that of the second resistor; specifically, a small resistance value of 100kΩ, 10kΩ, or even 0Ω can be selected. The second resistor works with the first resistor to maintain the equivalent resistance value after series connection at 1MΩ~20MΩ, maintaining compatibility with the resistance value of traditional fixed TIA resistors and ensuring the signal gain requirements during the data acquisition stage. The second end of the second resistor forms two key connections: one is directly connected to the output of the second amplifier, constructing a closed-loop feedback path for the transimpedance amplifier; the other is connected to the second input of the analog-to-digital converter, enabling the amplified and converted voltage signal to be accurately transmitted to the acquisition unit, ensuring the integrity of signal acquisition. The first end of the capacitor is also connected to the inverting input of the second amplifier, and the second end is connected to the second input of the analog-to-digital converter. The capacitor mainly plays the role of filtering and phase compensation, which can suppress high-frequency noise interference, prevent the circuit from oscillating during feedback switching, and improve the stability and linearity of signal conversion. As the execution unit for mode switching, the switching component, through precise coordination with the timing control signal, enables alternating operation between bias sustain mode and data acquisition mode. In bias sustain mode, the switching component switches the feedback path to a low-impedance state dominated by a small-value first resistor. Even in cases of abnormal leakage current caused by improper wearing or water contact with the electrodes (with a maximum tolerance of 100uA), it can prevent the output voltage of the second amplifier from exceeding the saturation swing, ensuring stable bias voltage. In data acquisition mode, the switching component switches the feedback path to a high-impedance state with the first and second resistors connected in series. This converts the weak 10nA~100nA current signal generated by the sensor into a voltage signal with appropriate amplitude, meeting the acquisition accuracy requirements of the analog-to-digital converter. Furthermore, this module is compatible with the programmable TIA resistor structure integrated within the chip, allowing the reuse of existing control switches to achieve dynamic bias control, thus balancing circuit integration and compatibility.

[0069] In one example, it also includes:

[0070] The timing control module has its output terminal electrically connected to the control terminal of the switching component. It is used to output periodic control signals to control the switching component to turn on and off, so that the bias control circuit alternately operates in bias maintenance mode and data acquisition mode.

[0071] Specifically, the bias control circuit also includes a timing control module, which serves as the core control unit for realizing the periodic switching of dual modes. Through precise timing logic design, it ensures the stable operation of the entire circuit. The output of the timing control module establishes a reliable electrical connection with the control terminal of the switching component, and can output a periodic control signal (such as a high or low level signal) with a fixed period and adjustable duty cycle to the switching component. The period and duty cycle of this control signal can be flexibly configured according to the application scenario of the electrochemical sensor (such as continuous blood glucose monitoring), which is suitable for the ultra-low power consumption requirements of button battery power supply, and can also meet the requirements of data acquisition accuracy and timing synchronization. The timing control module precisely controls the on / off state of the switching component through a preset logic program: when the output control signal closes the switching component, the feedback impedance of the dynamic feedback module switches to a small-value first resistor, and the bias control circuit enters the bias maintenance mode. At this time, even if there is abnormal leakage current caused by improper wearing or water contact with the electrodes (the maximum tolerance level is 100uA), the saturation of the second amplifier can be avoided, ensuring the stability of the sensor bias voltage. When the output control signal opens the switching component, the feedback impedance switches to a series combination of the first and second resistors, and the circuit switches to the data acquisition mode, converting the weak current signal of 10nA~100nA generated by the sensor into a voltage signal with appropriate amplitude for acquisition by the analog-to-digital converter. After the data acquisition is completed, the timing control module outputs a control signal again to close the switching component, and the circuit returns to the bias maintenance mode. This cycle repeats to achieve the alternating operation of the two working modes. In addition, the timing control module also has a timing synchronization function with the analog-to-digital converter to ensure that the data acquisition action is accurately matched with the high feedback impedance state, avoiding signal acquisition distortion caused by timing misalignment. At the same time, its output control signal also has anti-interference capability, which can effectively resist the influence of circuit noise or external interference on the switching control logic, further improving the working reliability and stability of the bias control circuit, especially suitable for application scenarios with strict requirements for timing accuracy and stability, such as continuous blood glucose monitoring.

[0072] In one example, the switch component includes:

[0073] A control switch, the first end of which is connected to the second end of the first resistor, and the second end of which is connected to the output of the second amplifier.

[0074] Specifically, the switching assembly implements its core function through a simple control switch. The first terminal of this control switch is connected to the series node between the first and second resistors (i.e., the second terminal of the first resistor), and its second terminal is directly connected to the output of the second amplifier. This means that the control switch is essentially connected in parallel with the second resistor. When the timing control module drives the control switch to close, the two ends of the second resistor are short-circuited, thus completely bypassing the feedback path. At this time, the feedback impedance from the output of the second amplifier to its inverting input is provided solely by the first resistor, and the circuit is in a low-gain, high-stability bias-maintaining mode. Conversely, when the timing control module drives the control switch to open, the second resistor is effectively inserted into the feedback loop, connected in series with the first resistor to form a high-resistance feedback path, and the circuit switches to a high-gain, high-sensitivity data acquisition mode. This design, using only a single switch, efficiently and reliably achieves dynamic switching of the feedback impedance with minimal components and the simplest control logic, reducing system complexity and cost while ensuring clear and rapid transitions between the two operating modes.

[0075] In one example, the switch component includes:

[0076] First control switch, second control switch, third control switch and fourth control switch;

[0077] The first terminal of the first control switch is connected to the second terminal of the first resistor, and the second terminal is connected to the output terminal of the second amplifier.

[0078] The first end of the second control switch is connected between the first resistor and the second resistor, and its second end is connected to the second end of the capacitor.

[0079] The first terminal of the third control switch is connected to the second terminal of the second resistor, and the second terminal of the second resistor is connected to the output terminal of the second amplifier.

[0080] The first terminal of the fourth control switch is connected to the second terminal of the second resistor, and its second terminal is connected to the second terminal of the capacitor.

[0081] Specifically, the first control switch is connected in parallel across the first resistor, and when closed, it short-circuits the first resistor; the third control switch is connected in parallel across the second resistor, and when closed, it short-circuits the second resistor. The second and fourth control switches are used to control the connection point of the compensation capacitor: the second control switch determines whether the capacitor is connected to the node between the first and second resistors, while the fourth control switch determines whether the capacitor is connected to the node between the second resistor and the output terminal of the second amplifier (i.e., the usual output node).

[0082] In one example, when the timing control module controls the control switch to close, the bias control circuit operates in bias sustain mode.

[0083] When the timing control module controls the control switch to be turned off, the bias control circuit operates in data acquisition mode.

[0084] Specifically, the timing control module outputs precise control signals to achieve real-time control of the on / off state of the control switch, thereby driving the bias control circuit to switch orderly between bias sustaining mode and data acquisition mode. When the timing control module outputs a closed control signal, the control switch responds and conducts. At this time, the second resistor in the dynamic feedback module is short-circuited, and the feedback impedance consists only of the small-value first resistor. The bias control circuit officially enters the bias sustaining mode. In this mode, because the resistance value of the first resistor is smaller than that of the traditional fixed TIA resistor, even if abnormal leakage occurs due to improper wearing or electrode contact with water, according to Ohm's law, the voltage drop generated by the leakage current across the first resistor is much lower than the saturation voltage of the second amplifier (for example, a 200nA leakage current only generates 2mV voltage through a 10kΩ R1). This effectively avoids amplifier saturation, ensuring that the potential difference between the reference electrode and the working electrode of the electrochemical sensor remains constant, guaranteeing that the sensor is in a stable bias state for a long time. Moreover, this mode is the main operating state of the sensor, meeting the ultra-low power consumption requirements of scenarios such as continuous blood glucose monitoring. When the timing control module outputs a disconnect control signal, the control switch responds and cuts off, the feedback impedance switches to a series combination of the first and second resistors, and the bias control circuit switches to data acquisition mode. At this time, the weak 10nA~100nA current signal generated by the sensor's working electrode is converted into a voltage signal of appropriate amplitude through a high-impedance series resistor network. This voltage signal can be accurately acquired by the analog-to-digital converter, meeting the accuracy requirements of data detection. Even if there is an abnormally large leakage current during the data acquisition phase, due to the short acquisition time, it will only cause a short-term bias anomaly in the sensor. After the acquisition is completed, the control switch closes again, the circuit returns to the bias maintenance mode, and the sensor can quickly recover its correct operating state, avoiding unreliable data or sensor damage caused by long-term bias anomalies. The switching between the two modes strictly follows the timing control logic, operating cyclically to ensure both bias stability and data acquisition accuracy, significantly improving the reliability of the sensor under complex operating conditions.

[0085] In one example, when the timing control module controls the first control switch to close, the second control switch to close, the third control switch to open, and the fourth control switch to open, the bias control circuit operates in bias sustaining mode.

[0086] When the timing control module controls the first control switch to open, the second control switch to open, the third control switch to close, and the fourth control switch to close, the bias control circuit operates in data acquisition mode.

[0087] Specifically, the timing control module outputs precise timing control signals to coordinate the on / off states of the first to fourth control switches, enabling precise switching of the bias control circuit between bias sustain mode and data acquisition mode. When the timing control module outputs a bias sustain mode control command, the first control switch closes, its first terminal is connected to the second terminal of the first resistor, and the second terminal is connected to the output terminal of the second amplifier, causing the second resistor to be short-circuited, and the feedback impedance consists only of the small-value first resistor; simultaneously, the second control switch closes, its first terminal is connected to the series node of the first and second resistors, and its second terminal is connected to the second terminal of the capacitor, connecting the capacitor to the feedback loop to perform filtering and phase compensation functions, suppressing noise interference; while the third and fourth control switches remain open to avoid the second resistor and additional paths affecting the low-impedance feedback path. At this point, the circuit enters the bias sustaining mode. Since the resistance of the first resistor is smaller than that of a traditional fixed TIA resistor, even if there is abnormal leakage due to improper wearing or water contact with the electrode, the voltage drop generated by the leakage current across the first resistor is much lower than the saturation voltage of the second amplifier. This effectively prevents amplifier saturation, ensures a constant potential difference between the reference electrode and the working electrode of the electrochemical sensor, and guarantees that the sensor remains in a stable bias state for a long time, meeting the ultra-low power consumption requirements of scenarios such as continuous blood glucose monitoring. When the timing control module outputs a data acquisition mode control command, the first and second control switches disconnect, cutting off the independent feedback path of the first resistor and the filtering path of the capacitor. The third control switch closes, with its first end connected to the second end of the second resistor and the second end connected to the output of the second amplifier, forming a series feedback impedance between the second and first resistors. The fourth control switch closes synchronously, with its first end connected to the second end of the second resistor and the second end connected to the second end of the capacitor, reconnecting the capacitor to the feedback loop to optimize signal stability. At this point, the circuit switches to data acquisition mode. The weak 10nA~100nA current signal generated by the sensor's working electrode is converted into a voltage signal of appropriate amplitude through a high-impedance series resistor network, which can be accurately acquired by the analog-to-digital converter, meeting the accuracy requirements of data detection. Even if there is an abnormally large leakage current during the acquisition phase, due to the short acquisition time, it will only cause a short-term abnormal bias in the sensor. After the acquisition is completed, the timing control module switches the control signal, and the circuit returns to the bias maintenance mode. The sensor can quickly recover to the correct working state, avoiding the problems of unreliable data or sensor damage caused by long-term abnormal bias. The on / off logic of each switch in both modes is matched to ensure the smoothness and reliability of mode switching, taking into account bias stability, data acquisition accuracy, and low power consumption.

[0088] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, but this is not intended to limit the invention. It should be noted that, unless otherwise specified, the embodiments and features described in the embodiments of the present invention can be combined with each other.

[0089] Example 1

[0090] like Figure 1 As shown, this embodiment provides an electrochemical sensor bias control circuit, including:

[0091] Amplifier 1, Electrochemical Sensor, Adjustable Resistor R LOAD Amplifier 2, resistor R1, resistor R2, control switch S1, capacitor C1, analog-to-digital converter and timing control module;

[0092] The non-inverting input of amplifier 1 receives the bias voltage V1, its inverting input is connected to the reference electrode RE of the sensor, and its output is connected to the counter electrode CE of the sensor. Through closed-loop feedback, the potential difference between the reference electrode RE and the working electrode WE is kept constant, ensuring the stability of the electrochemical reaction of the sensor.

[0093] Adjustable resistor R LOAD One end is connected to the working electrode WE of the sensor, and the other end is connected to the inverting input terminal of amplifier 2, and also to one input of the analog-to-digital converter; the non-inverting input terminal of amplifier 2 receives the bias voltage V2, which is used to set the operating point of amplifier 2, and its output terminal is connected to another path of the analog-to-digital converter. Amplifier 2 realizes the conversion of weak current to voltage.

[0094] Resistor R1 and resistor R2 are connected in series between the output terminal and the inverting input terminal of amplifier 2. Control switch S1 is connected in parallel with resistor R2, and capacitor C1 is connected in parallel across resistor R1 and resistor R2, and is also connected to another input of analog-to-digital converter. The feedback impedance can be switched by controlling the on and off of control switch S1, and capacitor C1 is used for filtering and noise suppression.

[0095] The timing control module outputs the control signal to control switch S1, while the analog-to-digital converter acquires the voltage signal converted by amplifier 2.

[0096] Resistor R1 + resistor R2 is equivalent to the original RTIA resistor, with a resistance value between 1MΩ and 20MΩ. Resistor R1 is smaller than resistor R2, for example, 100kΩ, 10kΩ, or even 0Ω.

[0097] The sensor is mostly in a biased state. In this state, control switch S1 is closed, and the TIA resistor (resistor R1) is very small. Even with large abnormal leakage current, amplifier 2 can still provide it without saturation. Analyzing previous abnormal leakage current scenarios, when the same 200nA leakage current is applied to the input of TIA amplifier 2, a voltage of 10kΩ x 200nA = 2mV is generated for the 10kΩ resistor R1, which is less than the saturation voltage of amplifier 2. The actual tolerable abnormal leakage current reaches the 100uA level.

[0098] When preparing to acquire data, disconnect the control switch S1 in advance. The current signal from the sensor is converted into a larger voltage through (resistor R1 + resistor R2) so that the analog-to-digital converter can acquire it.

[0099] After data acquisition is complete, the circuit switches to a smaller resistor (R1) to enter the bias state. This cycle repeats.

[0100] Even if a large leakage current exists during data acquisition, the short acquisition time will only cause a brief abnormal bias in the sensor. After data conversion, the sensor returns to a low-resistance bias state and can quickly recover to the correct state. This prevents bias voltage instability caused by abnormal conditions and greatly improves the stability of the sensor.

[0101] Example 2

[0102] like Figure 2 As shown, this embodiment provides an electrochemical sensor bias control circuit, including:

[0103] Amplifier 1, Electrochemical Sensor, Adjustable Resistor R LOAD Amplifier 2, resistor R1, resistor R2, first control switch S1a, second control switch S1b, third control switch S2a, fourth control switch S2b, capacitor C1, analog-to-digital converter and timing control module;

[0104] The non-inverting input of amplifier 1 receives the bias voltage V1, its inverting input is connected to the reference electrode RE of the sensor, and its output is connected to the counter electrode CE of the sensor. Through closed-loop feedback, the potential difference between the reference electrode RE and the working electrode WE is kept constant, ensuring the stability of the electrochemical reaction of the sensor.

[0105] Adjustable resistor R LOAD One end is connected to the working electrode WE of the sensor, and the other end is connected to the inverting input terminal of amplifier 2, and also to one input of the analog-to-digital converter; the non-inverting input terminal of amplifier 2 receives the bias voltage V2, which is used to set the operating point of amplifier 2, and its output terminal is connected to another path of the analog-to-digital converter. Amplifier 2 realizes the conversion of weak current to voltage.

[0106] Resistor R1 and resistor R2 are connected in series between the output terminal and the inverting input terminal of amplifier 2. The first terminal of the first control switch S1a is connected to the second terminal of resistor R1, and its second terminal is connected to the output terminal of amplifier 2. The first terminal of the second control switch S2a is connected between resistor R1 and resistor R2, and its second terminal is connected to the second terminal of capacitor C1. The first terminal of the third control switch S1b is connected to the second terminal of resistor R2, and its second terminal is connected to the output terminal of amplifier 2. The first terminal of the fourth control switch S2b is connected to the second terminal of resistor R2, and its second terminal is connected to the second terminal of capacitor C1.

[0107] The feedback impedance can be switched by controlling the on / off state of the first control switch S1a, the second control switch S1b, the third control switch S2a, and the fourth control switch S2b, while capacitor C1 is used for filtering and noise suppression.

[0108] The timing control module outputs the control signal to control switch S1, while the analog-to-digital converter acquires the voltage signal converted by amplifier 2.

[0109] Resistor R1 + resistor R2 is equivalent to the original RTIA resistor, with a resistance value between 1MΩ and 20MΩ. Resistor R1 is smaller than resistor R2, for example, 100kΩ, 10kΩ, or even 0Ω.

[0110] The sensor is mostly in a biased state. In this state, the first and second control switches S1a and S1b are closed, while the third and fourth control switches S2a and S2b are open, resulting in a very small TIA resistor (R1). Even with large abnormal leakage current, amplifier 2 can still provide it without saturation. Analyzing previous abnormal leakage current scenarios, when the same 200nA leakage current is applied to the input of TIA amplifier 2, a voltage of 10kΩ x 200nA = 2mV is generated for the 10kΩ resistor R1, which is less than the saturation voltage of amplifier 2. The actual tolerable abnormal leakage current reaches the 100uA level.

[0111] When preparing to acquire data, disconnect the first control switch S1a and the second control switch S1b in advance, and close the third control switch S2a and the fourth control switch S2b. The current signal of the sensor is converted into a larger voltage through (resistor R1 + resistor R2) so that the analog-to-digital converter can acquire it.

[0112] After data acquisition is complete, the circuit switches to a smaller resistor (R1) to enter the bias state. This cycle repeats.

[0113] Even if a large leakage current exists during data acquisition, the short acquisition time will only cause a brief abnormal bias in the sensor. After data conversion, the sensor returns to a low-resistance bias state and can quickly recover to the correct state. This prevents bias voltage instability caused by abnormal conditions and greatly improves the stability of the sensor.

[0114] Example 3

[0115] This embodiment provides an electrochemical sensor control system, including an electrochemical sensor and the electrochemical sensor bias control circuit described in Embodiment 1 or Embodiment 2.

[0116] The various embodiments of the present invention have been described above. These descriptions are exemplary and not exhaustive, nor are they limited to the disclosed embodiments. Many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the described embodiments.

Claims

1. An electrochemical sensor bias control circuit, characterized in that, include: The bias drive module is electrically connected to the counter electrode and the reference electrode of the electrochemical sensor and is used to output a drive signal to the counter electrode to maintain a constant potential difference between the reference electrode and the working electrode of the electrochemical sensor. A transimpedance amplifier module, whose input terminal is connected to the working electrode of the electrochemical sensor, is used to convert the current signal generated by the working electrode into a voltage signal. A dynamic feedback module is connected between the output and input terminals of the transimpedance amplifier module to switch the feedback impedance of the transimpedance amplifier module, thereby causing the bias control circuit to alternately operate in bias sustain mode and data acquisition mode. An analog-to-digital converter, whose input terminal is connected to the output terminal of the transimpedance amplifier module, is used to acquire the voltage signal output by the transimpedance amplifier module in the data acquisition mode; The transimpedance amplifier module includes: Adjustable resistor and second amplifier; One end of the adjustable resistor is connected to the working electrode, and the other end is connected to the inverting input terminal of the second amplifier and the first input terminal of the analog-to-digital converter, respectively. The non-inverting input of the second amplifier is used to receive the second bias voltage, and its output and inverting input are connected to the dynamic feedback module. The dynamic feedback module includes: First resistor, second resistor, capacitor, and switching assembly; The first end of the first resistor is connected to the inverting input of the second amplifier, and its second end is connected to the first end of the second resistor; The second end of the second resistor is connected to the output terminal of the second amplifier and the second input terminal of the analog-to-digital converter, respectively. The first end of the capacitor is connected to the inverting input of the second amplifier, and the second end is connected to the second input of the analog-to-digital converter. The switching assembly is used to enable the bias control circuit to operate alternately in bias maintenance mode and data acquisition mode. The resistance of the first resistor is less than the resistance of the second resistor.

2. The electrochemical sensor bias control circuit according to claim 1, characterized in that, The bias drive module includes: A first amplifier has a non-inverting input terminal for receiving a first bias voltage, an inverting input terminal connected to the reference electrode of the electrochemical sensor, and an output terminal connected to the counter electrode of the electrochemical sensor.

3. The electrochemical sensor bias control circuit according to claim 1, characterized in that, Also includes: The timing control module has its output terminal electrically connected to the control terminal of the switching component, and is used to output periodic control signals to control the on and off of the switching component, so that the bias control circuit alternately operates in bias maintenance mode and data acquisition mode.

4. The electrochemical sensor bias control circuit according to claim 3, characterized in that, The switching assembly includes: A control switch, the first end of which is connected to the second end of the first resistor, and the second end of which is connected to the output terminal of the second amplifier.

5. The electrochemical sensor bias control circuit according to claim 3, characterized in that, The switching assembly includes: First control switch, second control switch, third control switch and fourth control switch; The first end of the first control switch is connected to the second end of the first resistor, and the second end of the first control switch is connected to the output end of the second amplifier. The first end of the second control switch is connected between the first resistor and the second resistor, and its second end is connected to the second end of the capacitor; The first end of the third control switch is connected to the second end of the second resistor, and the second end of the third control switch is connected to the output end of the second amplifier. The first end of the fourth control switch is connected to the second end of the second resistor, and its second end is connected to the second end of the capacitor.

6. The electrochemical sensor bias control circuit according to claim 4, characterized in that, When the timing control module controls the control switch to close, the bias control circuit operates in bias sustain mode; When the timing control module controls the control switch to be turned off, the bias control circuit operates in data acquisition mode.

7. The electrochemical sensor bias control circuit according to claim 5, characterized in that, When the timing control module controls the first control switch to close, the second control switch to close, the third control switch to open, and the fourth control switch to open, the bias control circuit operates in bias sustain mode. When the timing control module controls the first control switch to open, the second control switch to open, the third control switch to close, and the fourth control switch to close, the bias control circuit operates in data acquisition mode.

8. An electrochemical sensor control system, characterized in that, It includes an electrochemical sensor and an electrochemical sensor bias control circuit as described in any one of claims 1-7.

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