Falling detection device for electrochemical sensor

Abstract

The utility model discloses a falling-off detection device for an electrochemical sensor. The falling-off detection device comprises a step signal generating circuit and a sensor fault conditioning circuit, wherein the step signal generating circuit is connected with the sensor fault conditioning circuit and transmits a step voltage signal generated by the step signal generating circuit to the sensor fault conditioning circuit; the sensor fault conditioning circuit is formed by combining a constant potential rectifier circuit and a small current amplifying circuit, the constant potential rectifier circuit is connected with the step signal generating circuit, receives a step voltage signal and then generates a transient current, and the constant potential rectifier circuit is connected with the electrochemical sensor and transmits the transient current to the electrochemical sensor; the small current amplification circuit is connected with the electrochemical sensor and detects the transient current received by the electrochemical sensor. The circuit is simple and reliable in structure, convenient to build, high in stability and low in material cost, the manufacturing cost is saved, and industrial mass production can be carried out.

Description

Technical Field

[0001] This utility model relates to the field of electrochemical sensors, and in particular to an electrochemical sensor shedding detection device. Background Technology

[0002] Devices equipped with electrochemical sensors typically have sensor detachment detection capabilities. Currently, there are generally two solutions on the market with this function. The first is to use mechanical anti-detachment mechanisms or hard switches for detection. This solution is bulky, unstable, and easily affects the sensor's weak signal, leading to increased detection errors. The second solution uses an integrated chip solution, such as the electrochemical sensor fault detection system and method disclosed in patent number ZL202010563695.X. This solution is costly, not conducive to mass production, and lacks marketability. Therefore, it is necessary to research an electrochemical sensor detachment detection device to solve the above problems. Summary of the Invention

[0003] The purpose of this invention is to address the above-mentioned problems by providing a simple and cost-effective electrochemical sensor shedding detection device.

[0004] To achieve the above objectives, the technical solution of this utility model is as follows:

[0005] An electrochemical sensor detachment detection device includes a step signal generation circuit and a sensor fault conditioning circuit. The step signal generation circuit is connected to the sensor fault conditioning circuit and transmits the step voltage signal generated by the step signal generation circuit to the sensor fault conditioning circuit. The sensor fault conditioning circuit is composed of a potentiostat circuit and a small current amplification circuit. The potentiostat circuit is connected to the step signal generation circuit and generates a transient current after receiving the step voltage signal. The potentiostat circuit is connected to the electrochemical sensor and transmits the transient current to the electrochemical sensor. The small current amplification circuit is connected to the electrochemical sensor and detects the transient current received by the electrochemical sensor.

[0006] Furthermore, the potentiostat circuit includes an operational amplifier U3B. The positive input terminal of operational amplifier U3B is connected to one end of resistors R13 and R14, respectively. The other end of resistor R13 is grounded, and the other end of resistor R14 is connected to a step signal generation circuit. The negative input terminal of operational amplifier U3B is connected to one end of resistor R12. The other end of resistor R12 is connected to one end of resistor R11 and one end of capacitor C4, respectively. The other end of capacitor C4 is connected to the counter electrode of the electrochemical sensor and the output terminal of operational amplifier U3B, respectively. The other end of resistor R11 is connected to the reference electrode of the electrochemical sensor. The positive power supply terminal of operational amplifier U3B is connected to the VCC terminal and one end of capacitor C3, respectively. The other end of capacitor C3 is grounded. The negative power supply terminal of operational amplifier U3B is connected to one end of capacitor C5, and the other end of capacitor C5 is grounded.

[0007] Furthermore, the low-current amplification circuit includes a transistor Q3 and an operational amplifier U3A. The collector of transistor Q3 is connected to the reference electrode of the electrochemical sensor, and the emitter of transistor Q3 is connected to the VCC terminal. The base of transistor Q3 and the working electrode of the electrochemical sensor are both connected to one end of resistor R16. The other end of resistor R16 is connected to the negative input terminal of operational amplifier U3A and one end of resistor R15. The other end of resistor R15 is connected to the output terminal of operational amplifier U3A and one end of resistor R17. The other end of resistor R17 is connected to the detection device and one end of capacitor C6. The other end of capacitor C6 is grounded. The positive input terminal of operational amplifier U3A is connected to one end of resistor R18, and the other end of resistor R18 is grounded.

[0008] Furthermore, the step signal generation circuit includes an operational amplifier signal subtraction circuit, an operational amplifier positive input conditioning circuit, and an operational amplifier U1. The negative input terminal of operational amplifier U1 is connected to the operational amplifier signal subtraction circuit, and the positive input terminal of operational amplifier U1 is connected to the operational amplifier positive input conditioning circuit. The positive power supply terminal of operational amplifier U1 is connected to VCC and one end of capacitor C1, with the other end of capacitor C1 grounded. The negative power supply terminal of operational amplifier U1 is connected to one end of capacitor C2, with the other end of capacitor C2 grounded. The output terminal of operational amplifier U1 and the operational amplifier signal subtraction circuit are both connected to one end of resistor R14 in the potentiostat circuit.

[0009] Furthermore, the operational amplifier signal subtraction circuit includes resistors R4, R6, and R2. One end of resistor R4 is connected to a 2.5V power supply, and the other end of resistor R4 is connected to one end of resistor R6. The other end of resistor R6 is connected to one end of resistor R2 and the negative input terminal of operational amplifier U1, respectively. The other end of resistor R2 is connected to one end of resistor R14 in the potentiostat circuit.

[0010] Furthermore, the operational amplifier's positive input conditioning circuit includes MOSFETs Q1 and Q2, resistors R3 and R8. The gate of MOSFET Q1 is connected to one end of resistor R5 and one end of resistor R1, respectively. The other end of resistor R5 serves as the ERROR1 control signal terminal. The other end of resistor R1 and one end of resistor R3 are both connected to a 2.5V power supply. The other end of resistor R3 is connected to the source of MOSFET Q1 and one end of resistor R7, respectively. The other end of resistor R7, one end of resistor R8, the drain of MOSFET Q1, and the drain of MOSFET Q2 are all connected to the positive input terminal of operational amplifier U1. The base of MOSFET Q2 is connected to one end of resistor R9 and one end of resistor R10, respectively. The other end of resistor R9 serves as the ERROR2 control signal terminal. The other ends of resistor R10, the other end of resistor R8, and the source of MOSFET Q2 are all grounded.

[0011] Furthermore, both the ERROR1 and ERROR2 control signal terminals are connected to the MCU chip and the MCU chip issues control signals. The MCU chip is an STM32F402RCT6, a 32-bit microcontroller based on high performance. The Cortex-M4 32-bit RISC core operates at frequencies up to 84MHz. The M4 core features a single-precision floating-point unit (FPU) and supports all... Single-precision data processing instructions and data types, featuring a DSP instruction set and an enhanced application-safe memory protection unit (MPU).

[0012] Compared with the prior art, the advantages and positive effects of this utility model are:

[0013] During normal detection operations, this invention periodically outputs signals from the ERROR1 and ERROR2 control signal terminals. These signals, after passing through a step signal generation circuit, generate a step voltage at the output of operational amplifier U1. This step voltage enters the sensor fault conditioning circuit, and after passing through operational amplifier U3B, generates a transient current that is transmitted to the electrochemical sensor. This transient current transmission process is detected by operational amplifier U3A. When operational amplifier U3A normally detects the transient current transmission signal, it indicates that the electrochemical sensor has not detached; when operational amplifier U3A does not detect the transient current transmission signal, it indicates that the electrochemical sensor has detached. Its circuit structure is simple and reliable, easy to assemble, highly stable, and has low material costs. Compared to integrated solutions, it significantly reduces manufacturing costs and can be mass-produced industrially. Furthermore, it allows for the specification of pulse intensity and width according to the characteristics of the electrochemical sensor without affecting its detection performance. It achieves electrochemical fault detection without affecting the electrochemical gas concentration detection effect, and has great market potential. Attached Figure Description

[0014] To more clearly illustrate the technical solutions in the embodiments of this utility model or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this utility model. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0015] Figure 1 This is a circuit diagram of a step signal generation circuit;

[0016] Figure 2 This is a circuit diagram of a sensor fault conditioning circuit.

[0017] Figure 3 This is a display effect diagram of the testing equipment. Detailed Implementation

[0018] The technical solutions of the present utility model will be clearly and completely described below with reference to the accompanying drawings of the embodiments. Obviously, the described embodiments are only some embodiments of the present utility model, and not all embodiments. Based on the embodiments of the present utility model, any modifications, equivalent substitutions, improvements, etc., made by those skilled in the art to all other embodiments obtained without creative effort should be included within the protection scope of the present utility model.

[0019] This embodiment discloses an electrochemical sensor detachment detection device, including a step signal generation circuit and a sensor fault conditioning circuit. The step signal generation circuit is connected to the sensor fault conditioning circuit and transmits the step voltage signal generated by the step signal generation circuit to the sensor fault conditioning circuit.

[0020] like Figure 1 As shown, the step signal generation circuit includes an operational amplifier signal subtraction circuit, an operational amplifier positive input conditioning circuit, and an operational amplifier U1. The negative input terminal of operational amplifier U1 is connected to the operational amplifier signal subtraction circuit, and the positive input terminal of operational amplifier U1 is connected to the operational amplifier positive input conditioning circuit. The positive power supply terminal of operational amplifier U1 is connected to VCC and one end of capacitor C1, with the other end of capacitor C1 grounded. The negative power supply terminal of operational amplifier U1 is connected to one end of capacitor C2, with the other end of capacitor C2 grounded. The output terminal of operational amplifier U1 and the operational amplifier signal subtraction circuit are both connected to one end of resistor R14 in the potentiostat circuit.

[0021] The operational amplifier's positive input conditioning circuit includes MOSFETs Q1 and Q2, resistors R3 and R8. The gate of MOSFET Q1 is connected to one end of resistor R5 and one end of resistor R1. The other end of resistor R5 serves as the ERROR1 control signal terminal. The other end of resistor R1 and one end of resistor R3 are both connected to a 2.5V power supply. The other end of resistor R3 is connected to the source of MOSFET Q1 and one end of resistor R7. The other end of resistor R7, one end of resistor R8, the drain of MOSFET Q1, and the drain of MOSFET Q2 are all connected to the positive input terminal of operational amplifier U1. The base of MOSFET Q2 is connected to one end of resistor R9 and one end of resistor R10. The other end of resistor R9 serves as the ERROR2 control signal terminal. The other ends of resistor R10, the other end of resistor R8, and the source of MOSFET Q2 are all grounded. The ERROR1 and ERROR2 control signal terminals are both connected to the MCU chip, and the MCU chip issues control signals.

[0022] The operational amplifier's positive input conditioning circuit has two control signals, ERROR1 and ERROR2, issued by the MCU chip. ERROR1 is current-limited and protected by resistor R5, then passes through MOSFET Q1. The gate of MOSFET Q1 is pulled up by resistor R1 to ensure its switching state during idle. ERROR2 is current-limited and protected by resistor R9, then passes through MOSFET Q2. The gate of MOSFET Q2 is pulled down by resistor R10 to ensure its switching state during idle. MOSFETs Q1 and Q2 form a half-bridge-like circuit connected to the resistor divider network on the right side, composed of resistors R3, R7, and R8. MOSFET Q1 is connected across resistor R7, and MOSFET Q2 is connected across resistor R8. This part of the circuit ultimately generates a variable output voltage, V2, at the positive input of operational amplifier U1. When the ERROR1 and ERROR2 signals are in an indeterminate state, MOSFET Q1 is turned off due to its gate being clamped by resistor R1, and MOSFET Q2 is turned off due to its gate being clamped by resistor R10. The final voltage level at the positive input of the op-amp is 1.25V. When the ERROR1 signal is output as 0 by the MCU, MOSFET Q1 is turned on, resistor R7 is short-circuited, and MOSFET Q2 remains off. The final voltage level at the positive input of the op-amp is 2.5V. When the ERROR2 signal is output as 1 by the MCU, MOSFET Q2 is turned on, resistor R8 is short-circuited, and MOSFET Q1 remains off. The final voltage level at the positive input of the op-amp is 0V. In this way, three different voltage levels can be obtained at the positive input of operational amplifier U1.

[0023] The operational amplifier signal subtraction circuit includes resistors R4, R6, and R2. One end of resistor R4 is connected to a 2.5V power supply, and the other end of resistor R4 is connected to one end of resistor R6. The other end of resistor R6 is connected to one end of resistor R2 and the negative input terminal of operational amplifier U1. The other end of resistor R2 is connected to one end of resistor R14 in the potentiostat circuit.

[0024] The operational amplifier signal subtraction circuit primarily implements a subtractor function. The negative input signal of operational amplifier U1 is powered by 2.5V, which is V1. The positive input signal V2 comes from the front-end operational amplifier's positive input conditioning circuit. After passing through operational amplifier U1, the output is Vo. The logical arithmetic implemented by operational amplifier U1 is Vo = 2V2 - V1. Combining the three voltage levels of the front-end operational amplifier's positive input conditioning circuit (0V, 1.25V, 2.5V, and V1), it can be deduced that the output Vo of operational amplifier U1 also has three states: 0V, 2.5V, and -2.5V.

[0025] like Figure 2As shown, the sensor fault conditioning circuit is a three-electrode electrochemical sensor circuit. This circuit is divided into two parts: one part uses a potentiostat circuit composed of U3B electrodes, and the other part uses a small current amplification circuit composed of U3A electrodes. The potentiostat circuit is connected to the step signal generation circuit and receives the step voltage signal to generate a transient current. The potentiostat circuit is connected to the electrochemical sensor and transmits the transient current to the electrochemical sensor. The small current amplification circuit is connected to the electrochemical sensor and detects the transient current received by the electrochemical sensor.

[0026] The potentiostat circuit includes an operational amplifier U3B. The positive input terminal of operational amplifier U3B is connected to one end of resistors R13 and R14, respectively. The other end of resistor R13 is grounded. The other end of resistor R14 is connected to the output terminal of operational amplifier U1 in the step signal generation circuit and one end of resistor R2. The negative input terminal of operational amplifier U3B is connected to one end of resistor R12. The other end of resistor R12 is connected to one end of resistor R11 and one end of capacitor C4, respectively. The other end of capacitor C4 is connected to the counter electrode of the electrochemical sensor and the output terminal of operational amplifier U3B, respectively. The other end of resistor R11 is connected to the reference electrode of the electrochemical sensor. The positive power supply terminal of operational amplifier U3B is connected to the VCC terminal and one end of capacitor C3, respectively. The other end of capacitor C3 is grounded. The negative power supply terminal of operational amplifier U3B is connected to one end of capacitor C5, and the other end of capacitor C5 is grounded.

[0027] The low-current amplification circuit includes a transistor Q3 and an operational amplifier U3A. The collector of transistor Q3 is connected to the reference electrode of the electrochemical sensor, and the emitter of transistor Q3 is connected to the VCC terminal. The base of transistor Q3 and the working electrode of the electrochemical sensor are both connected to one end of resistor R16. The other end of resistor R16 is connected to the negative input terminal of operational amplifier U3A and one end of resistor R15. The other end of resistor R15 is connected to the output terminal of operational amplifier U3A and one end of resistor R17. The other end of resistor R17 is connected to the detection device and one end of capacitor C6. The other end of capacitor C6 is grounded. The positive input terminal of operational amplifier U3A is connected to one end of resistor R18, and the other end of resistor R18 is grounded.

[0028] When the electrochemical sensor is not detached, the circuit periodically outputs signals controlled by ERROR1 and ERROR2, generating a step voltage pulse at the output of operational amplifier U1. This pulse, after passing through resistor R14, generates a transient current at the positive input of operational amplifier U3B. This transient current then flows into the electrochemical sensor, charging its internal capacitance. This process is detected by operational amplifier U3A. If operational amplifier U3A does not detect the transient current, it indicates either a sensor malfunction or a connection problem. By detecting this step voltage, a closed loop for transmission and reception is achieved, thus realizing the detachment detection function of the electrochemical sensor. Figure 3 As shown, the detection equipment can display that channel 2 is the signal change V2 of the operational amplifier positive input conditioning circuit, channel 3 is the output Vo of the step signal generation circuit, and channel 1 is the output OUT of the sensor fault conditioning circuit.

[0029] During normal detection operations, this invention periodically outputs signals from the ERROR1 and ERROR2 control signal terminals. These signals, after passing through a step signal generation circuit, generate a step voltage at the output of operational amplifier U1. This step voltage enters the sensor fault conditioning circuit, and after passing through operational amplifier U3B, generates a transient current that is transmitted to the electrochemical sensor. This transient current transmission process is detected by operational amplifier U3A. When operational amplifier U3A normally detects the transient current transmission signal, it indicates that the electrochemical sensor has not detached; when operational amplifier U3A does not detect the transient current transmission signal, it indicates that the electrochemical sensor has detached. Its circuit structure is simple and reliable, easy to assemble, highly stable, and has low material costs. Compared to integrated solutions, it significantly reduces manufacturing costs and can be mass-produced industrially. Furthermore, it allows for the specification of pulse intensity and width according to the characteristics of the electrochemical sensor without affecting its detection performance. It achieves electrochemical fault detection without affecting the electrochemical gas concentration detection effect, and has great market potential.

Claims

1. An electrochemical sensor shedding detection apparatus, characterized by: The electrochemical sensor detachment detection device includes a step signal generation circuit and a sensor fault conditioning circuit. The step signal generation circuit is connected to the sensor fault conditioning circuit and transmits the step voltage signal generated by the step signal generation circuit to the sensor fault conditioning circuit. The sensor fault conditioning circuit is composed of a potentiostat circuit and a small current amplification circuit. The potentiostat circuit is connected to the step signal generation circuit and generates a transient current after receiving the step voltage signal. The potentiostat circuit is connected to the electrochemical sensor and transmits the transient current to the electrochemical sensor. The small current amplification circuit is connected to the electrochemical sensor and detects the transient current received by the electrochemical sensor.

2. The electrochemical sensor shedding detection apparatus of claim 1, wherein: The potentiostat circuit includes an operational amplifier U3B. The positive input terminal of operational amplifier U3B is connected to one end of resistors R13 and R14, respectively. The other end of resistor R13 is grounded, and the other end of resistor R14 is connected to a step signal generation circuit. The negative input terminal of operational amplifier U3B is connected to one end of resistor R12. The other end of resistor R12 is connected to one end of resistor R11 and one end of capacitor C4, respectively. The other end of capacitor C4 is connected to the counter electrode of the electrochemical sensor and the output terminal of operational amplifier U3B, respectively. The other end of resistor R11 is connected to the reference electrode of the electrochemical sensor. The positive power supply terminal of operational amplifier U3B is connected to VCC and one end of capacitor C3, respectively. The other end of capacitor C3 is grounded. The negative power supply terminal of operational amplifier U3B is connected to one end of capacitor C5, and the other end of capacitor C5 is grounded.

3. The electrochemical sensor shedding detection apparatus of claim 2, wherein: The low-current amplification circuit includes a transistor Q3 and an operational amplifier U3A. The collector of transistor Q3 is connected to the reference electrode of the electrochemical sensor, and the emitter of transistor Q3 is connected to the VCC terminal. The base of transistor Q3 and the working electrode of the electrochemical sensor are both connected to one end of resistor R16. The other end of resistor R16 is connected to the negative input terminal of operational amplifier U3A and one end of resistor R15. The other end of resistor R15 is connected to the output terminal of operational amplifier U3A and one end of resistor R17. The other end of resistor R17 is connected to the detection device and one end of capacitor C6. The other end of capacitor C6 is grounded. The positive input terminal of operational amplifier U3A is connected to one end of resistor R18, and the other end of resistor R18 is grounded.

4. The electrochemical sensor shedding detection apparatus of claim 3, wherein: The step signal generation circuit includes an operational amplifier signal subtraction circuit, an operational amplifier positive input conditioning circuit, and an operational amplifier U1. The negative input of operational amplifier U1 is connected to the operational amplifier signal subtraction circuit, and the positive input of operational amplifier U1 is connected to the operational amplifier positive input conditioning circuit. The positive power supply terminal of operational amplifier U1 is connected to VCC and one end of capacitor C1, with the other end of capacitor C1 grounded. The negative power supply terminal of operational amplifier U1 is connected to one end of capacitor C2, with the other end of capacitor C2 grounded. The output terminal of operational amplifier U1 and the operational amplifier signal subtraction circuit are both connected to one end of resistor R14 in the potentiostat circuit.

5. The electrochemical sensor shedding detection apparatus of claim 4, wherein: The operational amplifier signal subtraction circuit includes resistors R4, R6, and R2. One end of resistor R4 is connected to a 2.5V power supply, and the other end of resistor R4 is connected to one end of resistor R6. The other end of resistor R6 is connected to one end of resistor R2 and the negative input terminal of operational amplifier U1. The other end of resistor R2 is connected to one end of resistor R14 in the potentiostat circuit.

6. The electrochemical sensor shedding detection apparatus of claim 5, wherein: The operational amplifier's positive input conditioning circuit includes MOSFETs Q1 and Q2, resistors R3 and R8. The gate of MOSFET Q1 is connected to one end of resistor R5 and one end of resistor R1. The other end of resistor R5 serves as the ERROR1 control signal terminal. The other end of resistor R1 and one end of resistor R3 are both connected to a 2.5V power supply. The other end of resistor R3 is connected to the source of MOSFET Q1 and one end of resistor R7. The other end of resistor R7, one end of resistor R8, the drain of MOSFET Q1, and the drain of MOSFET Q2 are all connected to the positive input terminal of operational amplifier U1. The base of MOSFET Q2 is connected to one end of resistor R9 and one end of resistor R10. The other end of resistor R9 serves as the ERROR2 control signal terminal. The other ends of resistor R10, the other end of resistor R8, and the source of MOSFET Q2 are all grounded.

7. The electrochemical sensor shedding detection apparatus of claim 6, wherein: The ERROR1 and ERROR2 control signal terminals are both connected to the MCU chip and the MCU chip issues control signals.

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