Automatic calibration device for electrochemical sensor

Abstract

The utility model discloses an automatic calibration device for an electrochemical sensor, which comprises a standard gas supply source, a nitrogen supply source, a mass flow meter, a gas concentration analyzer, the electrochemical sensor, a drying oven and a main control computer, the standard gas supply source and the nitrogen supply source are respectively connected with the mass flow meter through gas pipelines; a pressure reducing valve and an electromagnetic control valve are arranged on the gas conveying pipeline, the mass flow meter is communicated with an inlet of the gas concentration analyzer through a pipeline, an outlet of the gas concentration analyzer is connected with the drying oven through a pipeline, and the electrochemical sensor is arranged in the drying oven; the mass flow meter, the gas concentration analyzer, a signal acquisition board of the electrochemical sensor, the drying oven, the pressure reducing valve and the electromagnetic control valve are all electrically connected with the main control computer. According to the utility model, the gas sensor can be continuously tested for 24 hours, the manual operation is reduced, and the calibration efficiency and accuracy are improved.

Description

Technical Field

[0001] The utility model relates to the technical field of electrochemical sensor calibration, in particular to an automatic calibration device for an electrochemical sensor. Background Art

[0002] At present, gas detectors are widely used in indoor and outdoor air detection fields. Electrochemical sensors are widely used in various detectors due to their advantages such as sensitive reaction, fast response, and high accuracy. An electrochemical sensor is a sensor that estimates the concentration of a measured gas based on the change in oxidation or reduction current generated at the electrode due to the chemical reaction of the measured gas. During the operation of the electrochemical sensor, its performance will decay over time and with the increase in the detection amount, resulting in zero drift and long-term drift phenomena, affecting the measurement accuracy of the sensor. Therefore, it is necessary to calibrate the sensor before use and regularly.

[0003] The calibration process of the existing electrochemical sensor is as follows: First, the electrochemical sensor is placed in an environment without a target gas (or called "zero gas", such as pure air) to record the initial response or baseline value of the sensor; after completing the baseline test, it is necessary to manually switch to standard gases of different concentrations for calibration. However, when measuring linearity, response time, and repeatability, it is necessary to manually switch dozens of times, and manually switch the oven temperature where the electrochemical sensor is placed more than a dozen times. There are many manual operations, which require careful manual operation and monitoring, and it is difficult to achieve complete continuous automation. Summary of the Invention

[0004] To solve the above problems, the purpose of the utility model is to provide an automatic calibration device for an electrochemical sensor with a reasonable structural design and high automation degree.

[0005] To achieve the above invention purpose, the utility model adopts the following technical scheme:

[0006] An automatic calibration device for an electrochemical sensor, which includes a standard gas supply source, a nitrogen supply source, a mass flow meter, a gas concentration analyzer, an electrochemical sensor, an oven, and a main control computer. The standard gas supply source and the nitrogen supply source are respectively connected to the mass flow meter through gas transmission pipelines. Pressure reducing valves and electromagnetic control valves are arranged on the gas transmission pipelines. The mass flow meter is connected to the inlet of the gas concentration analyzer through a pipeline. The outlet of the gas concentration analyzer is connected to the oven through a pipeline. The electrochemical sensor is arranged in the oven; the mass flow meter, the gas concentration analyzer, the signal acquisition board of the electrochemical sensor, the oven, the pressure reducing valve, and the electromagnetic control valve are all electrically connected to the main control computer.

[0007] Further, the above-mentioned electrochemical sensor is a three-electrode system electrochemical sensor, including a working electrode, a reference electrode, and a counter electrode.

[0008] Furthermore, the signal acquisition board of the electrochemical sensor is provided with a signal acquisition circuit, which includes a single-chip minimum system, a signal conditioning circuit, a multi-channel analog switch circuit, an analog-to-digital conversion circuit, an RS485 transceiver circuit, a USB to serial port circuit, a data storage circuit, and a power supply circuit for the above circuits, wherein:

[0009] The signal conditioning circuit, whose input end is connected to the electrode of the electrochemical sensor, is used to amplify the current signal collected by the electrode, convert it into a voltage signal, and filter the voltage signal;

[0010] The multi-channel analog switch circuit, whose input end is connected to the output end of the signal conditioning circuit, is used to control the time-sharing A / D conversion of the analog voltage signal output by the signal conditioning circuit;

[0011] The analog-to-digital conversion circuit has an input end connected to the output end of the multi-channel analog switch circuit and an output end connected to the single-chip microcomputer minimum system, and is used to convert the analog voltage signal output by the signal conditioning circuit into a digital signal and transmit the digital signal to the single-chip microcomputer minimum system;

[0012] The RS485 transceiver circuit is connected to the single-chip microcomputer minimum system and is used to send and receive data with the single-chip microcomputer minimum system;

[0013] The USB to serial port circuit is connected to the single-chip microcomputer minimum system and is used for two-way data communication between the single-chip microcomputer minimum system and the main control computer;

[0014] The data storage circuit is connected to the single-chip microcomputer minimum system and is used for storing data signals.

[0015] Furthermore, the above-mentioned signal acquisition circuit also includes a Bluetooth control circuit and a WIFI control circuit, which are connected to the single-chip microcomputer minimum system.

[0016] Furthermore, the above-mentioned signal acquisition circuit also includes a key control circuit connected to the input end of the single-chip microcomputer minimum system.

[0017] Furthermore, the above-mentioned signal acquisition circuit also includes a buzzer control circuit, which is connected to the output end of the single-chip microcomputer minimum system.

[0018] Furthermore, the above-mentioned signal acquisition circuit also includes a lithium battery power supply circuit, and the lithium battery power supply circuit is connected to the single-chip microcomputer minimum system.

[0019] Furthermore, in the above-mentioned single-chip microcomputer minimum system, the single-chip microcomputer model is STM32F103VET6.

[0020] Due to the technical solution described above, the utility model has the following advantages:

[0021] The automatic calibration device for the electrochemical sensor does not require the full participation of operators. It can continuously test the gas sensor for 24 hours, reduce manual operation, improve the calibration efficiency and accuracy, and control the pressure reducing valve, electromagnetic control valve, mass flow meter, gas concentration analyzer, signal acquisition board of the electrochemical sensor, and oven at different times to realize the automatic operation of different test items. It is convenient to operate, has high working efficiency, can achieve complete continuous automation, and has good popularization and application value. Description of the Drawings

[0022] Figure 1 is a schematic structural diagram of the automatic calibration device for the electrochemical sensor of the utility model;

[0023] Figure 2 is Figure 1 a schematic structural diagram of the signal acquisition board of the electrochemical sensor in

[0024] In the figure: 1 - standard gas supply source; 2(a, b) - pressure reducing valve; 3(a, b) - electromagnetic control valve; 4(a, b) - gas transmission pipeline; 5 - mass flow meter; 6 - gas concentration analyzer; 7 - oven; 8 - electrochemical sensor; 9 - waste gas treatment device; 10 - main control computer; 11 - nitrogen supply source. Detailed Embodiments

[0025] The technical solution of the utility model will be further described in detail below with reference to the drawings and embodiments.

[0026] As Figure 1 、 2As shown in the figure, the automatic calibration device for the electrochemical sensor includes a standard gas supply source 1, a nitrogen supply source 11, a mass flow meter 5, a gas concentration analyzer 6, an electrochemical sensor 8, an oven 7, a main control computer 10, and an exhaust gas treatment device 9. The standard gas supply source 1 is connected to the mass flow meter 5 through a gas transmission pipeline 4a, and a pressure reducing valve 2a and an electromagnetic control valve 3a are arranged on the gas transmission pipeline 4a. The nitrogen supply source 11 is connected to the mass flow meter 5 through a gas transmission pipeline 4b, and a pressure reducing valve 2b and an electromagnetic control valve 3b are arranged on the gas transmission pipeline 4b. The mass flow meter 5 is communicated with the inlet of the gas concentration analyzer 6 through a pipeline. The outlet of the gas concentration analyzer is connected to the air inlet of the oven 7 through a pipeline. The electrochemical sensor 8 is arranged in the oven. The air outlet of the oven is connected to the exhaust gas treatment device 9 through a pipeline for filtering and treating the exhaust gas after calibration and calibration. The mass flow meter 5, the gas concentration analyzer 6, the signal acquisition board of the electrochemical sensor 8, the oven 7, the pressure reducing valves 2a and 2b, and the electromagnetic control valves 3a and 3b are all electrically connected to the main control computer 10.

[0027] The pressure reducing valves 2a and 2b respectively reduce the pressure of the high-pressure gas provided by the standard gas supply source 1 and the nitrogen supply source 11. The mass flow meter 5 controls the gas flow rate through the main control computer 10. The gas concentration analyzer 6 is used to analyze the concentration of the mixed gas and upload it to the main control computer 10 for data comparison. When there is a difference, the main control computer adjusts the mass flow meter 5 to reach the required gas concentration. The oven 7 is used to provide the temperature required for testing the electrochemical sensor 8. The signal acquisition board of the electrochemical sensor 8 is used to acquire the electrical signal that changes when contacting the gas, convert it into a gas concentration value, and transmit it to the main control computer 10 for data analysis and storage.

[0028] The above-mentioned electrochemical sensor 8 is a three-electrode system electrochemical sensor, including a working electrode WE, a reference electrode RE, and a counter electrode CE.

[0029] As Figure 2 shown in the figure, a signal acquisition circuit is arranged on the signal acquisition board of the above-mentioned electrochemical sensor. The signal acquisition circuit includes a minimum single-chip microcomputer system, a signal conditioning circuit, a multi-channel analog switch circuit, an analog-to-digital conversion circuit, an RS485 transceiver circuit, a USB-to-serial port circuit, a data storage circuit, and a power supply circuit for supplying power to the above-mentioned each circuit. The minimum single-chip microcomputer system includes a single-chip microcomputer, a crystal oscillator circuit, a reset circuit, a filtering circuit, a clock circuit, and a BOOT selection circuit connected to the single-chip microcomputer. The clock circuit uses a PCF8563 clock chip. The model of the single-chip microcomputer is STM32F103VET6, which is powered by +3.3V and has an external working clock of 8MHz. Among them,

[0030] The signal conditioning circuit, whose input end is connected to the three electrodes of the electrochemical sensor, is used to determine that the potential of the reference electrode RE and the counter electrode CE is constant, and to amplify the current signal collected by the working electrode WE, convert it into a voltage signal, and filter the voltage signal to remove high-frequency signals and clutter signals to obtain a clean voltage signal;

[0031] The multi-channel analog switch circuit, whose input end is connected to the output end of the signal conditioning circuit, is used to control the time-sharing A / D conversion of the analog voltage signal output by the signal conditioning circuit;

[0032] The analog-to-digital conversion circuit, whose input end is connected to the output end of the multi-channel analog switch circuit and whose output end is connected to the single-chip microcomputer minimum system, is used to convert the analog voltage signal output by the signal conditioning circuit into a digital signal, and transmit the digital signal to the single-chip microcomputer minimum system to realize real-time sampling. The single-chip microcomputer minimum system converts the received digital signal into a corresponding gas concentration value;

[0033] The RS485 transceiver circuit is connected to the single-chip microcomputer minimum system and is used to upload the gas concentration value result output by the single-chip microcomputer minimum system to the main control computer;

[0034] The USB to serial port circuit is connected to the single-chip microcomputer minimum system and is used for two-way data communication between the single-chip microcomputer minimum system and the main control computer;

[0035] The data storage circuit is connected to the single-chip microcomputer minimum system and is used for storing data signals.

[0036] The above-mentioned signal acquisition circuit also includes a Bluetooth control circuit and a WIFI control circuit, which are connected to the single-chip computer minimum system. The wireless transmission control channels of the Bluetooth control circuit and the WIFI control circuit can provide flexible and convenient remote control capabilities.

[0037] The above-mentioned signal acquisition circuit also includes a key control circuit, which is connected to the input end of the single-chip microcomputer minimum system.

[0038] The above-mentioned signal acquisition circuit also includes a buzzer control circuit, which is connected to the output end of the single-chip microcomputer minimum system.

[0039] The above-mentioned signal acquisition circuit also includes an indicator light circuit, which is connected to the output end of the single-chip microcomputer minimum system.

[0040] The above-mentioned signal acquisition circuit also includes a lithium battery power supply circuit, and the lithium battery power supply circuit is connected to the single-chip microcomputer via the clock circuit in the single-chip microcomputer minimum system.

[0041] The above are only the preferred embodiments of the present utility model, rather than a limitation to the present utility model. Without departing from the spirit and scope of the present utility model, all equivalent changes and modifications made according to the scope of the patent application of the present utility model shall fall within the scope of the patent protection of the present utility model.

Claims

1. An automatic calibration device for an electrochemical sensor, characterized in that: It includes a standard gas supply source, a nitrogen supply source, a mass flow meter, a gas concentration analyzer, an electrochemical sensor, an oven, and a main control computer. The standard gas supply source and the nitrogen supply source are respectively connected to the mass flow meter through a gas pipeline, and a pressure reducing valve and an electromagnetic control valve are arranged on the gas pipeline. The mass flow meter is connected to the inlet of the gas concentration analyzer through a pipeline, and the outlet of the gas concentration analyzer is connected to the oven through a pipeline. The electrochemical sensor is arranged in the oven; the mass flow meter, the gas concentration analyzer, the signal acquisition board of the electrochemical sensor, the oven, the pressure reducing valve and the electromagnetic control valve are all electrically connected to the main control computer.

2. The electrochemical sensor automatic calibration device according to claim 1, characterized in that: The electrochemical sensor is a three-electrode system electrochemical sensor, including a working electrode, a reference electrode and a counter electrode.

3. The electrochemical sensor automatic calibration device according to claim 1, characterized in that: The signal acquisition board of the electrochemical sensor is provided with a signal acquisition circuit, which includes a single-chip minimum system, a signal conditioning circuit, a multi-channel analog switch circuit, an analog-to-digital conversion circuit, an RS485 transceiver circuit, a USB to serial port circuit, a data storage circuit, and a power supply circuit for the above circuits, wherein: The signal conditioning circuit, whose input end is connected to the electrode of the electrochemical sensor, is used to amplify the current signal collected by the electrode, convert it into a voltage signal, and filter the voltage signal; The multi-channel analog switch circuit, whose input end is connected to the output end of the signal conditioning circuit, is used to control the time-sharing A / D conversion of the analog voltage signal output by the signal conditioning circuit; The analog-to-digital conversion circuit has an input end connected to the output end of the multi-channel analog switch circuit and an output end connected to the single-chip microcomputer minimum system, and is used to convert the analog voltage signal output by the signal conditioning circuit into a digital signal and transmit the digital signal to the single-chip microcomputer minimum system; The RS485 transceiver circuit is connected to the single-chip microcomputer minimum system and is used to send and receive data with the single-chip microcomputer minimum system; The USB to serial port circuit is connected to the single-chip microcomputer minimum system and is used for two-way data communication between the single-chip microcomputer minimum system and the main control computer; The data storage circuit is connected to the single-chip microcomputer minimum system and is used for storing data signals.

4. The electrochemical sensor automatic calibration device according to claim 3, characterized in that: The signal acquisition circuit also includes a Bluetooth control circuit and a WIFI control circuit, which are connected to the single-chip microcomputer minimum system.

5. The electrochemical sensor automatic calibration device according to claim 3, characterized in that: The signal acquisition circuit also includes a key control circuit connected to the input end of the single-chip microcomputer minimum system.

6. The electrochemical sensor automatic calibration device according to claim 3, characterized in that: The signal acquisition circuit also includes a buzzer control circuit connected to the output end of the single-chip microcomputer minimum system.

7. The electrochemical sensor automatic calibration device according to claim 3, characterized in that: The signal acquisition circuit also includes a lithium battery power supply circuit, and the lithium battery power supply circuit is connected to the single-chip microcomputer minimum system.

8. The electrochemical sensor automatic calibration device according to claim 3, characterized in that: In the single-chip minimum system, the single-chip model is STM32F103VET6.

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