Portable electrochemical gas detection device based on YSZ type solid-state sensor

Abstract

The invention belongs to the technical field of electrochemical detection, and particularly relates to a portable electrochemical gas detection device based on a YSZ type solid-state sensor, which comprises a YSZ type solid-state sensor and a portable terminal which are electrically connected through an aviation plug, the portable terminal comprises a shell and a circuit board assembled in the shell. A power supply module, a micro-control unit and a signal amplification module are arranged on the circuit board, and the micro-control unit is electrically connected with the power supply module and the signal amplification module; the aviation plug is arranged on the circuit board and penetrates out of the shell. The aviation plug is electrically connected with the signal amplification module and the micro-control unit. The YSZ type solid sensor is a three-electrode sensor. Compared with the prior art, the problem that in the prior art, a portable device is poor in sensitivity and precision is solved, and rapid and accurate detection of the gaseous electrochemical phenomenon is achieved.

Description

Technical Field

[0001] The invention belongs to the technical field of electrochemical detection, and in particular relates to a portable electrochemical gas detection device based on a YSZ type solid-state sensor. Background Art

[0002] Electrochemical analysis is a method of chemical analysis of electrochemical phenomena using electrochemical principles, and is an important branch of instrumental analysis. By measuring parameters such as current, voltage, and conductivity in the electrochemical system, the composition and concentration of gaseous electrochemical phenomena can be studied and analyzed. This analysis method includes different experimental techniques such as potentiometry, amperometry, and impedance analysis. Commonly used instruments include potentiometers, conductivity meters, electrochemical workstations, and electrochemical analyzers. Electrochemical analysis has the advantages of high sensitivity, high selectivity, real-time, strong quantitative analysis capabilities, all-weather performance, as well as automation and online monitoring. It has been widely used in environmental monitoring, biomedicine, materials science, and energy fields, providing an important analytical means for scientific research and industrial applications.

[0003] Electrochemical instruments are a type of equipment and instruments specifically used for electrochemical experiments and analysis. They are mainly used to measure, record and store electrical parameters such as current, voltage, charge, capacitance, potential difference, conductivity, etc. related to electrochemical phenomena in electrochemical processes, in order to study the kinetics of chemical reactions, the concentration of substances in solutions, reaction rates and other information. Its components include electrode systems, electrolytic cells, power supplies and circuits, measurement and recording systems, control systems, accessories and attachments, and the basic part is the instrument hardware. The most commonly used electrochemical instrument on the market is the electrochemical workstation, which generally has disadvantages such as large size, high power consumption, high cost, and complex operation.

[0004] The electrochemical system is an electrochemical cell containing electrodes, electrolytes and electrode interfaces constructed in electrochemical experiments. It is generally divided into two-electrode system and three-electrode system. The three-electrode system is more common in electrochemical research. It contains two circuits. One circuit consists of a working electrode (WE) and a reference electrode (RE), which controls the potential between the working electrode and the reference electrode. The other circuit consists of a working electrode (WE) and an auxiliary electrode (CE), which mainly allows the current to flow smoothly. During the experiment, a diaphragm is usually used to separate them. Due to the presence of the reference electrode, the potential control of the working electrode of the three-electrode system is more accurate.

[0005] Gaseous electrochemical phenomena refer to phenomena that occur in the gas phase and involve electrochemical reactions. They are coupled and controlled by the conservation of current of charges in the electrolyte and electrodes and the conservation of mass of each solute in the electrolyte. They involve the participation of gas molecules in the electrochemical system and are usually related to gas redox reactions and gas sensing.

[0006] The YSZ type solid-state sensor is a solid oxide sensor based on oxygen ion transport, where YSZ stands for yttria-stabilized zirconium. YSZ type solid-state sensors are commonly used to measure oxygen concentration and are widely used in oxygen sensors, fuel cells, solid oxide fuel cells (SOFCs), and other oxygen ion transport related fields. Its working principle is based on the migration of oxygen ions in oxide solid electrolytes. Under high temperature conditions, oxygen ions can pass through the YSZ solid electrolyte, resulting in a potential difference between the electrodes. By measuring this potential difference, the concentration of oxygen in the gas mixture can be determined. The advantages of the YSZ type solid-state sensor include high response speed, good stability and reliability, and a wide measurement range. In addition, it also has a high operating temperature range, which can perform stable measurements in high temperature environments, and is suitable for application scenarios that require high temperature operation.

[0007] Portable electrochemical detection devices are often faced with challenges in terms of sensitivity and accuracy while being portable. Therefore, one of the current research objectives is to improve the sensitivity and measurement accuracy of portable electrochemical detection devices to meet the needs of high-precision analysis.

[0008] In addition, portable electrochemical detection devices usually require sample processing and preparation, which greatly increases the complexity of operation and affects the accuracy of test results. Therefore, the second purpose of the current research is to simplify the sample processing process and improve the efficiency and accuracy of sample processing. Summary of the invention

[0009] The purpose of the present invention is to provide a portable electrochemical gas detection device based on a YSZ solid-state sensor in order to solve at least one of the above problems, so as to solve the problem of poor sensitivity and accuracy of portable devices in the prior art. This solution realizes rapid and accurate detection of gaseous electrochemical phenomena.

[0010] The purpose of the present invention is achieved through the following technical solutions:

[0011] A portable electrochemical gas detection device based on a YSZ solid-state sensor, comprising a YSZ solid-state sensor and a portable terminal electrically connected via an aviation plug;

[0012] The portable terminal comprises a housing and a circuit board assembled inside the housing;

[0013] The circuit board is provided with a power module, a micro control unit and a signal amplification module, and the micro control unit is electrically connected to the power module and the signal amplification module;

[0014] The aviation plug is arranged on the circuit board and passes through the housing, and the aviation plug is electrically connected to the signal amplification module and the micro control unit respectively;

[0015] The YSZ type solid sensor is a three-electrode sensor.

[0016] Preferably, the portable electrochemical gas detection device also includes a heating module, which includes a heating relay arranged on a circuit board and a heating element arranged on a YSZ type solid sensor; the heating relay is electrically connected to the power module, and the heating element is electrically connected to the heating relay via an aviation plug.

[0017] Preferably, the signal amplification module includes an instrument amplifier, an operational amplifier and a feedback resistor; the operational amplifier is electrically connected to the instrument amplifier to form a two-stage amplification circuit, and the feedback resistor is an adjustable resistor and is electrically connected to the operational amplifier to form a variable gain amplification circuit.

[0018] Preferably, the operational amplifier is a differential amplifier.

[0019] Preferably, the microcontroller unit MCU includes an analog-to-digital conversion module ADC, and the analog-to-digital conversion of the ADC is used to realize signal exchange between the microcontroller unit and external components.

[0020] Preferably, a digital-to-analog conversion module DAC is also connected between the micro control unit and the aviation plug.

[0021] Preferably, the portable electrochemical gas detection device further comprises a display module, the shell is provided with an opening for assembling the display module, and the display module is electrically connected to the micro control unit via a serial port.

[0022] Preferably, the portable electrochemical gas detection device further comprises a communication module, the communication module is electrically connected to the micro control unit, and the communication module is used to establish a communication connection with an external data processing device and / or a data storage device.

[0023] Preferably, the communication module includes a Bluetooth serial port and a UART interface.

[0024] Preferably, the portable electrochemical gas detection device further comprises an indicator light, and the indicator light is electrically connected to the micro control unit.

[0025] Preferably, the housing comprises a front cover and a rear cover which are plug-fitted; a plurality of mating shafts are arranged on the inner side of the front cover, and the circuit board is assembled inside the housing via the mating shafts.

[0026] Preferably, there is a clearance fit between the circuit board and the matching shaft.

[0027] The working principle of the present invention is:

[0028] The power module supplies power to each unit and module. The YSZ solid sensor transmits the detection signal to the signal amplification module for signal amplification. The amplified signal is input to the micro control unit for data processing.

[0029] Compared with the prior art, the present invention has the following beneficial effects:

[0030] 1. The present invention provides a portable electrochemical gas detection device based on a YSZ solid sensor, which can be handheld and can realize rapid detection of the gas to be detected without any external computer equipment.

[0031] 2. The handheld electrochemical gas detection device of the present invention has high test accuracy. AD623 and LM358 are used together to form a two-stage amplification system. By using the AD623 instrument amplifier, weak signals are accurately amplified while noise and interference are suppressed to the maximum extent. LM358 provides additional signal processing capabilities as the second-stage amplification and buffering, helping to maintain the quality of the amplified signal and reduce errors caused by signal transmission or external interference. Both are low-cost, and the device has the advantages of small size, high sensitivity and good accuracy.

[0032] 3. The YSZ solid-state sensor of the present invention uses YSZ as the ion conductive layer and cooperates with high electrochemical catalytic activity materials as the sensitive electrode. By adjusting different sintering temperatures (between 1050°C and 1200°C), the micromorphology of the sensitive electrode layer is changed. In this way, sensitive electrode layers with different pore structures are obtained, and the microstructure of the sensitive electrode is optimized. This design helps to accelerate the gas to be measured to reach the three-phase interface in the electrochemical reaction, thereby improving the high selectivity and sensitivity of the sensor to the gas to be measured.

[0033] 4. The present invention further stably applies an excitation signal generated by a DAC signal generating circuit between the working electrode and the reference electrode, and tests the constant potential and detection current error of the system through a YSZ three-electrode solid-state sensor, verifying that the detection system has the advantages of high accuracy, good stability, and good repeatability, and can basically achieve rapid detection of gas concentration. It is suitable for occasions that require rapid detection of the concentration of a certain gas to be tested or for occasions where manual detection of the concentration of some toxic and harmful gases is difficult, such as post-disaster source search, gas leakage, olfactory navigation, daily pipeline inspection, etc.

[0034] 5. The present invention adopts the design of STM32 microcontroller in digital circuit design, adds Taojingchi serial port display screen, can display data in real time, and the user login interface can be designed as a safe and friendly interaction. The design of the whole circuit strives to be miniaturized and high-performance. It usually consumes low power at work, the switching speed of the components is fast and the response is rapid, and the specified tasks can be completed in a shorter time, thereby saving energy and resources. The circuit elements have high stability and reliability under appropriate working conditions, and are not affected by environmental factors such as temperature and humidity. No additional noise and distortion are introduced in the transmission and processing of digital signals, so it has high precision and accuracy.

[0035] 6. The three-electrode system design of the present invention provides a bias voltage for the gas sensor, changes the catalytic activity of the YSZ material, enhances the reaction activity of the gas to be measured, and causes oxidation or reduction reaction; at the same time, the current method is used to measure the gas concentration.

[0036] 7. The device of the present invention has a simple structure, is easy to operate, and is cheap and portable. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 Schematic diagram of the structure of a portable electrochemical gas detection device, wherein a) is a schematic diagram of the front side of the circuit board, b) is a schematic diagram of the back side of the circuit board, c) is a schematic diagram of the structure of the rear cover, and d) is a schematic diagram of the structure of the front cover;

[0038] Figure 2 It is a schematic diagram of the relationship between various modules and units in the portable electrochemical gas detection device;

[0039] Figure 3 It is a circuit diagram of a micro control unit in a portable electrochemical gas detection device;

[0040] Figure 4 It is a circuit diagram of each voltage stabilizing module in a portable electrochemical gas detection device;

[0041] Figure 5 It is a circuit diagram of a signal amplification module in a portable electrochemical gas detection device;

[0042] Figure 6 It is a circuit diagram of a digital-to-analog conversion module in a portable electrochemical gas detection device;

[0043] Figure 7 It is a circuit diagram of a heating module in a portable electrochemical gas detection device;

[0044] Figure 8 This is the working response result of the comparative test 1;

[0045] Fig. 9To compare the working response results of Test 2;

[0046] Fig.10 To compare the working response results of test 3;

[0047] In the figure: 1-rear cover; 2-front cover; 3-power module; 4-display module; 5-power switch; 6-aviation plug; 7-micro control unit; 8-instrument amplifier; 9-operational amplifier; 10-digital-to-analog conversion module; 11-heating button; 12-reset button; 13-communication module; 14-heating relay; 15-circuit board; 16-matching shaft; 17-plug board; 18-feedback resistor. DETAILED DESCRIPTION

[0048] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. The following embodiments are implemented based on the technical solution of the present invention, and provide detailed implementation methods and specific operation processes, but the protection scope of the present invention is not limited to the following embodiments.

[0049] The present invention is described in more detail in the following paragraphs by way of example with reference to the accompanying drawings. It should be noted that the accompanying drawings are all in a relatively simplified form and are not in exact proportions, and are only used to conveniently and clearly assist in explaining the purpose of the embodiments of the present invention.

[0050] In the description of the present invention, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0051] The handheld electrochemical gas detection device according to an embodiment of the present invention is described in detail below with reference to the accompanying drawings.

[0052] Example

[0053] A portable electrochemical gas detection device based on a YSZ solid-state sensor, such as Figure 1-7 As shown, it includes a YSZ type solid state sensor and a portable terminal electrically connected via an aviation plug 6;

[0054] The portable terminal comprises a housing and a circuit board 15 mounted inside the housing;

[0055] The circuit board 15 is provided with a power module 3, a micro control unit 7 and a signal amplification module, and the micro control unit 7 is electrically connected to the power module 3 and the signal amplification module;

[0056] The aviation plug 6 is arranged on the circuit board 15 and passes through the housing. The aviation plug 6 is electrically connected to the signal amplification module and the micro control unit 7 respectively.

[0057] The YSZ type solid sensor is a three-electrode sensor.

[0058] More specifically, in this embodiment:

[0059] The portable electrochemical gas detection device is a handheld electrochemical gas detection device, such as Figure 1-3 ,include:

[0060] A portable terminal includes a front cover 2, a rear cover 1 and a circuit board 15, wherein the front cover 2, the rear cover 1 and the circuit board 15 are assembled together through a hole-shaft clearance fit. The connection between the front cover 2 and the rear cover 1 is preferably a plug-in design, and the opening and closing of the internal cavity of the shell are realized through the protruding plug plate 17 arranged along the circumference of the front cover 2 and the slot arranged along the circumference of the rear cover 1. The top of the shell is provided with an opening for passing an aviation plug 6, and the bottom of the shell is also provided with a power interface connected to the cavity for inserting a power switch 5; the aviation plug 6 and the power switch 5 are both connected to the circuit board 15.

[0061] The microcontroller unit 7 is connected to each module and other circuits in the gas detection device for data processing, receiving and issuing instructions. Its internal 12-bit resolution ADC analog-to-digital conversion module can provide 4096 different analog values, provides an internal reference voltage of 3.3V, and has a maximum sampling rate of up to 2.5MSPS. It supports differential input mode, which helps to improve signal quality and reduce noise interference.

[0062] The model of the metal aviation plug 6 is GX12-5-core straight pin (gold-plated), the material of which is zinc alloy, and is used to connect the gas sensor and the micro control unit 7.

[0063] YSZ solid-state gas sensor (YSZ solid-state sensor), the gas sensor is connected to the circuit board 15 through the metal aviation plug 6, and is used to receive the detection data of the gas electrochemical reaction and transmit it to the microcontroller unit 7 on the circuit board 15. The front of the gas sensor is a three-electrode reaction system, which includes a working electrode, a reference electrode and an auxiliary electrode. Depending on the gas being measured, the working electrode (i.e., the sensitive electrode) will be coated with sensitive materials of different components; the back of the gas sensor is provided with two heating electrodes, and the measurement temperature will also be different as the test gas changes; both settings are to achieve the best response of the specific gas and the sensor reaction.

[0064] Amplification module (signal amplification module), the amplification module includes an instrumentation amplifier 8, an operational amplifier 9 and a feedback resistor 18, the operational amplifier 9 is electrically connected to the instrumentation amplifier 8 to form a two-stage amplification circuit, such as Figure 5 As shown. The YSZ solid-state sensor is connected to the circuit board 15 of the portable electrochemical gas detection device through the metal aviation plug 6 hardware. The analog voltage signal from the sensor is first input to the input pins of the instrument amplifier 8, which are pin 2 (IN-) and pin 3 (IN+). Among them, pin 1 (RG) is the gain setting pin, which is connected to the ground through the external resistor R39 to determine the gain of the first-stage amplifier; pin 5 (REF) is the reference voltage pin, which is used to set the limit level of the output signal; pin 6 (OUT) is connected to R40 to pass the output signal to the operational amplifier 8. The instrument amplifier 8 performs preliminary amplification of the signal while maintaining the integrity of the signal and reducing noise. The signal processed by the instrument amplifier 8 is output from pin 6 (OUT), coupled through capacitor C47 and passed to pin 2 (IN-) of the next-stage operational amplifier 9 for further amplification and possible signal shaping. The gain of the operational amplifier 9 is adjusted by the adjustable feedback resistor 18 (R42) to meet different measurement ranges and accuracy requirements. The amplified signal is output from pin 1 (OUT1) of the operational amplifier 9 and sent to the analog-to-digital converter ADC in the micro control unit 7 to be converted into a digital signal (input from pin 35 of the micro control unit 7). The quantized data is processed by the micro control unit 7. The design of this amplification module makes the signal processing flexible and efficient, and is suitable for environmental monitoring and analysis equipment that require precise measurement and control. Specifically, the instrument amplifier 8 provides high-precision primary amplification, which has a high input impedance and can directly receive weak analog signals from the gas sensor without generating a load on the output of the sensor; the operational amplifier 9 provides a second-stage amplification to further adjust the signal amplitude to adapt to the subsequent ADC input requirements. This stage can also be used for filtering and signal shaping. The feedback resistor 18 is an adjustable resistor, and forms a feedback loop between pin 2 (IN-) and pin 1 (OUT1) of the operational amplifier 9, and is electrically connected to it to form a variable gain amplifier circuit. The size of its resistance directly affects the gain of the amplifier and the overall amplification factor of the circuit. Therefore, its amplification factor can be adjusted according to the range requirements.

[0065] The heating circuit (heating module) includes a heating element, a heating relay 14 and a heating button 11. The heating element is arranged on the YSZ solid-state gas sensor for heating the gas sensor; the heating relay 14 is arranged on the circuit board 15, which is connected to the heating element through the aviation plug 6, and the heating relay 14 is also connected to the power module 3; the heating button 11 is used to control the heating relay 14, and the corresponding contact is closed or disconnected by operating the heating button 11, thereby enabling the heating relay 14 to be powered on or off, thereby realizing precise control and management of the heating device. The circuit also includes Figure 4 The voltage conversion circuit (LM317AG) in the gas sensor is used to convert the required voltage (the 12V voltage input by the power module 3 is converted into 10V for heating the sensor). The heating element uses a heating electrode, which is set on the back of the gas sensor. By heating the gas sensor, the electrolyte conduction is promoted on the one hand, and the catalytic activity of the sensitive material to the gas is improved on the other hand.

[0066] The display module 4 adopts Tao Jingchi serial port display screen, which is assembled at the proof opening of the shell, and realizes the connection between the microcontroller unit 7 and the serial port screen through serial communication, so as to realize data transmission. Specifically, Tao Jingchi's USARTHMI HST024042 is adopted to interact with the user MCU through the serial port J3 (USART232). Among them, J3 is a pin header, including 4 pins, of which pin 1 is grounded, pin 2 is connected to pin 77 of STM32, pin 3 is connected to pin 78 of STM32, and pin 4 is connected to VCC_5V power supply. When the MCU sends data to the serial port screen, the serial data is sent through the TX pin (pin 77); when receiving data from the serial port screen, the MCU receives the serial data through the RX pin (pin 78).

[0067] The communication module 13 is used to establish a communication connection with an external device. The communication module 13 includes a Bluetooth serial port and a UART interface, which respectively realize wireless and wired transmission of data, and transmit the data to an external data processing device or data storage device for data processing and storage.

[0068] The power module 3 is connected to the micro control unit 7 and the power switch 5 (push type), and the power supply can be controlled by pressing the power switch 5. The input battery of the power module 3 is a 12V lithium polymer battery.

[0069] Indicator light: The indicator light is connected to the micro control unit 7. When the indicator light flashes once, it means that a sampling measurement process is completed.

[0070] A matching shaft 16 is also provided inside the front cover 2, which matches with the opening on the circuit board 15 to complete the assembly and positioning of the circuit board 15, so that the display module 4 can just correspond to the opening on the shell. The circuit board 15 is fixed to the front cover 2 through the clearance fit of the shaft hole and the hole on the circuit board 15, which can reduce friction and wear and improve the service life and efficiency of mechanical assembly. In addition, the front cover 2 and the rear cover 1 of the shell are connected in a plug-in manner to achieve opening and closing, which improves waterproofness and safety.

[0071] The power switch 5 is located at the bottom of the circuit board 15 . A six-pin self-locking switch is used as the power switch 5 . The power switch 5 extends out of the housing for operation by the user.

[0072] The portable electrochemical gas detection device is also provided with a reset button 12, which is electrically connected to the micro control unit 7 and is used to reset each circuit.

[0073] The main working principle of the YSZ solid-state gas sensor is as follows: In the atmosphere of testing gases of different concentrations, the counter electrode (CE) serves as the loop part of the current and provides a stable reaction area; the reference electrode (RE) provides a stable reference voltage; the sensitive electrode (WE), i.e. the working electrode, undergoes oxidation or reduction reactions to varying degrees. Different chemical reactions cause a potential difference between the sensitive electrode and the reference electrode, and the concentration of the measured gas can be determined based on the relationship between this potential difference and the gas concentration. According to the principle of thermodynamic equilibrium, the oxygen ions and electrode electrons in the YSZ solid electrolyte will migrate relative to each other. When the chemical reactions on each electrode reach equilibrium, an electric potential is generated, and the potential magnitude E satisfies the Nernst equation.

[0074] This embodiment includes an STM32 microcontroller unit 7, an electrochemical detection module, a display module 4, a button module, an amplification module, an analog-to-digital conversion module, a communication module 13, and a power module 3; the power module 3 supplies power to the handheld electrochemical gas detection device; a heating button 11 and a reset button 12 together constitute a button module; the STM32 microcontroller unit 7 uses an ARM STM32L496 series STM32L496ZG chip designed and produced by STMicroelectronics as a microprocessor. Figure 3This is the hardware circuit diagram of the STM32 microcontroller unit 7, in which the microcontroller unit 7: pin 7 is connected to the power switch 5 to receive 3.3V power supply; pins 8 and 9 are connected to the crystal oscillator circuit, and the crystal oscillator Y1 provides a clock signal for the operation of the STM32 microcontroller unit 7; pin 25 NRST is connected to the soft reset button 12, and the reset circuit is around the button; pins 28, 35, and 47 are the analog signal input pins of the built-in ADC of the control unit, which are used to sample, quantize and encode external analog signals and store them in data registers; pins 75 and 137 are connected to the sampling lights LED1 and LED2, and the two lights flash alternately once to represent the end of a sampling; pins 92 and 93 are connected to the pin header for leading out ports, which can be connected to Bluetooth modules, burning programs, etc.

[0075] Although the voltage and current resolution can meet the needs of electrochemical detection, the measurement error will be large, so measures are taken to add an amplification module; the ADC analog-to-digital conversion module uses a 24-bit high-resolution analog-to-digital conversion element HY3116, and the data output rate can reach up to 7680SPS; the DAC digital-to-analog conversion module 10 selects DAC8162 to achieve high-precision (16-bit) DAC conversion.

[0076] The STM32 microcontroller unit 7 is connected to the output end of the metal aviation plug 6, and is combined with the serial port display screen to form a display module 4, which is composed of a DAC circuit element DAC8162 and connected components (including Figure 4 The regulators LM257dHV-5, 1117-3V3 and LM317AG and their connected diodes, inductors and filter capacitors form a voltage stabilizing circuit) forming a digital-to-analog conversion circuit voltage stabilizing circuit. Specifically, LM2576dHV-5 is used as a switching regulator, pin 1 (V_DIN) is used to receive the unstable input 12V voltage, pin 4 (Feedback) is used as a feedback pin to detect the output voltage and adjust the internal switch to maintain a stable output, L3 is used for energy storage and current smoothing, D1 provides reverse current protection and assists in forming a filter network, and pin 2 (OUTPUT) outputs a stable 5V voltage to pin 9 (AVdd) and pin 5 (VCC 5V) of DAC8162; LM317AG is used as an adjustable linear regulator to provide an adjusted output voltage by adjusting the external resistors R11 and R12 connected to pin 1; 1117-3V3 is used as a linear regulator to receive the 5V voltage output from the LM2576HV-5 and convert it into a stable 3.3V output. The above three regulators work in series to achieve multi-stage step-down, ensuring that the DAC can receive a stable and accurate power supply. Further, Figure 6The DAC8162 in the circuit provides the voltage signal of the result digital-to-analog conversion through pin 1 (VoutA) and pin 2 (VoutB), which is used to drive the display module 4; pin 6 (SYNC), pin 7 (SCLK), pin 8 (Din) and pin 6 (SPI NSS) constitute the serial peripheral interface SPI, which is connected to pin 43 of the micro control unit 7 through SN74LVC8T245 to receive the digital signal sent by the micro control unit 7. The amplifier module is composed of instrument amplifier 8AD623, operational amplifier 9LM358 and connected components to form a two-stage amplifier circuit. The first stage (AD623) provides precise primary amplification to process weak or sensitive signals; the second stage (LM358) is used to further adjust the signal and provide a level suitable for input to a microprocessor or analog-to-digital converter. The voltage regulator circuit converts the 12V input voltage into a 3.3V reference voltage, providing a stable low-ripple reference voltage for analog front ends such as ADC, DAC, and operational amplifier circuits. The analog differential signal input by the YSZ solid-state sensor is passed through the operational amplifier 9 to suppress common-mode noise, increase the amplitude of the differential signal, and transform it into a voltage signal that can be detected by the STM32 microcontroller unit 7, thereby improving the anti-interference ability of the system; then, the operational amplifier 9LM358 is used to achieve impedance matching, buffer and isolate the ADC, protect the ADC, and further adjust the signal to provide a level suitable for input to a microprocessor or an analog-to-digital converter; the digital signal processed by the ADC is transmitted to the L496ZG chip through the I2C interface for data processing, the input voltage is smoothed by the sliding average method to remove noise interference, and the processed digital signal is then output as an analog waveform through the DAC, and the detection results can be displayed in real time on the display module 4, and the detection results can also be transmitted to the PC end through the communication module 13 including UART and Bluetooth for data storage and further processing. When the current method is used to measure the gas concentration, the UART protocol can be used to implement human-computer interaction on the Taojingchi USARTHMI (HST024042) serial port display to dynamically adjust the ADC output bias to change the catalytic activity of the material. The specific process is that the detected digital voltage signal is transmitted to the 14-bit digital-to-analog converter DAC8162 through the GPIO pin of the STM32 chip to be converted into an analog voltage signal, which is applied to the counter electrode and reference electrode of the YSZ solid-state sensor after passing through the aviation plug 6; under the action of the analog voltage signal, the catalytic activity of the sensitive material of the YSZ solid-state sensor changes, and a redox reaction different from that before the bias voltage is applied occurs on the sensor surface. The weak current signal formed is converted into a detectable current as the analog signal input to the YSZ solid-state sensor. During the entire test process, the flashing of the sampling light once represents the completion of a measurement; in addition, the heating relay 14 of model 943-1C-5DS, the heating element, and the heating button 11 together form Figure 7The heating module in the test can drive and control the heating relay 14 through the heating button 11 during the test, which can promote the conductivity of the electrolyte in the reaction on the one hand, and improve the catalytic activity of the sensitive material to the gas on the other hand; in addition, by adjusting the adjustable feedback resistor 18, the corresponding operational amplifier 9 in the amplification module can be adjusted accordingly, so as to match the range switching requirements of various measurement ranges. After the test is completed, the system enters the waiting state, and the system can be reset to perform the next electrochemical test.

[0077] In order to verify the accuracy of the portable voltage-based electrochemical gas detection device of the present invention, an electrochemical gas detection experiment was carried out. The specific operation is as follows:

[0078] The gas sensing performance of gas sensors is studied using traditional static testing methods.

[0079] The comparative test equipment is equipped with a linear DC power supply to provide a stable current to the Pt heater, and then the working temperature of the gas sensor is adjusted by changing the current; the sensor signal is received by a digital multimeter (Agilent 34970A) and saved by a computer connected to it.

[0080] The test environment is to prepare different concentrations of NO2 by diluting standard gas (26.5ppm NO2, balanced by O2 and air) with air. The test steps are as follows: first, place the sensor in a closed gas collecting pipe filled with air to stabilize it. Next, introduce NO2 gas with different concentration gradients into the gas collecting pipe, and after the voltage signal reaches stability, record the voltage value of this state. In the YSZ gas sensor, nickel ferrite is used as the sensitive electrode and connected to the positive electrode / signal acquisition pin of the Agilent instrument / portable electrochemical gas device, and Pt is used as the reference electrode and connected to the negative electrode / reference pin of the Agilent instrument / portable electrochemical gas device. The response value ΔV of the sensor is obtained by calculating the difference between the two electrode / pin voltage values. The voltage signal measured by the YSZ solid-state gas sensor is converted into digital and recorded by a computer. The gas detection example and the compliance of the main performance indicators are shown in the figure. Figure 8 , 9 , as shown in 10.

[0081] The detection signal is led out through the wire and collected by Agilent's signal collection terminal / input into the signal collection pin of the circuit board, and the data is recorded and the waveform is drawn in real time.

[0082] Figure 8 The standard response measured by the Agilent instrument and the gas response waveform displayed by the portable electrochemical detection device of the present invention are respectively shown under the same NO2 gas detection environment (comparative test 1), and the changes of the two are consistent.

[0083] Fig. 9It is a YSZ solid-state sensor made of nickel ferrite and iron oxide sensitive materials fired at 1200 degrees Celsius. The portable detection device adjusts the feedback resistor 18 to make its ideal signal amplification factor 21, gives the optimal heating voltage 13V, and measures the reaction of NO2 gas with a concentration of 1.5ppm (comparative test 2). The data measured by Agilent 34970A digital multimeter is used as the baseline for comparison. It is easy to see that the response range of the left figure is -36.00mV to -20.36mV, and the response range of the right figure after 21 times magnification is -1333mV to -999mV, and the detection error is within one percent; and the change trends of the two are consistent.

[0084] Furthermore, in order to verify the repeatability of the portable electrochemical detection device of the present invention, the device was given a heating voltage of 13V, and repeated experiments were performed using NO2 gas of different concentrations, with the ideal magnification being 21 (Comparative Experiment 3). The resulting response diagram is shown in FIG. Fig.10 As shown, the left and right figures are the results of three repeated experiments of the device measuring 3ppm and 1.5ppm NO2 gas using the same YSZ solid-state sensor under the same heating voltage. There are three peaks with consistent trends and similar responses in the figures, indicating that when the data is graphically represented, the result curves or data points of the repeated experiments are very close or overlap, indicating that the device exhibits stable performance. Therefore, it can be explained that the handheld voltage method electrochemical gas detection device of this scheme has a fast response speed, high detection accuracy, and good repeatability.

[0085] According to the handheld electrochemical gas detection device of the present embodiment, the front cover 2 and the rear cover 1, the YSZ type solid-state gas sensor, the amplification module, the analog-to-digital conversion ADC circuit, the heating circuit, the display module 4, the communication module 13, the microcontroller unit 7, the power module 3 and the indicator light and other key components are integrated to achieve accurate detection of multiple gas components. The device adopts a miniaturized design, and integrates components such as sensors, controllers, and display screens in a housing composed of the front cover 2 and the rear cover 1. This design makes the device more compact, while protecting the internal components from external influences, and overcomes the shortcomings of the electrochemical workstation, which is bulky, cumbersome to operate, and expensive. It not only has the advantages of good portability, fast real-time response, and low cost, but also realizes the automation and intelligence of gas detection. Through wired or wireless communication technology, the detection data can be transmitted to the background management system in real time for data analysis and early warning. This innovative design breaks the limitations of traditional large-scale fixed gas detection stations. The equipment is easy to carry and use, and can be used for gas detection in every corner of the room, greatly improving the efficiency, range and frequency of gas detection, which is of great significance to ensuring personnel safety and production process monitoring. In general, the innovative design of this handheld gas detection device fills the shortcomings of the electrochemical workstation and has broad application prospects and important social value.

[0086] In the handheld electrochemical detection system of this solution, the microcontroller unit 7 uses the ARM STM32L496ZG microprocessor as the main control chip to realize concentration detection and complete the mutual communication with the peripheral devices. Figure 3 This is the hardware circuit diagram of the STM32 microcontroller unit 7. The ADC inside the main control chip is 12 bits, and the power supply reference voltage is 3.3V. Therefore, it can be calculated that the minimum voltage that the STM32 chip can distinguish is 0.8mV, and the corresponding minimum resolution current is 1nA. This scheme also stably applies the excitation signal generated by the DAC signal generation circuit between the working electrode and the reference electrode, and tests and studies the sensitive characteristics of the sensor under different environments through the classic YSZ three-electrode electrochemical model. The constant potential and detection current error of the system were tested, and it was verified that the detection system has the advantages of high accuracy, good stability, and good repeatability. It can realize the functions of current method and voltage method measurement, and can basically realize the rapid detection of electrochemical experiments and thus realize the application in the field of gas sensing.

[0087] Compared with the prior art, the present invention provides a handheld electrochemical detection device based on a YSZ solid-state sensor. It is based on a YSZ sensor, controlled by STM32, and composed of a series of test circuits. It provides a more convenient, fast, low-cost and accurate solution for chemical analysis and detection. It has the advantages of portability, real-time, low cost, simple operation, high sensitivity, etc.

[0088] The above description of the embodiments is to facilitate the understanding and use of the invention by those skilled in the art. It is obvious that those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative work. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the present invention should be within the scope of protection of the present invention.

Claims

1. A portable electrochemical gas detection device based on a YSZ solid-state sensor, characterized in that: It includes a YSZ type solid state sensor and a portable terminal which are electrically connected via an aviation plug (6); The portable terminal comprises a housing and a circuit board (15) mounted inside the housing; The circuit board (15) is provided with a power module (3), a micro control unit (7) and a signal amplification module, and the micro control unit (7) is electrically connected to the power module (3) and the signal amplification module; The aviation plug (6) is arranged on the circuit board (15) and extends out of the housing. The aviation plug (6) is electrically connected to the signal amplification module and the micro control unit (7) respectively. The YSZ type solid sensor is a three-electrode sensor.

2. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 1, characterized in that: The portable electrochemical gas detection device further comprises a heating module, wherein the heating module comprises a heating relay (14) arranged on a circuit board (15) and a heating element arranged on a YSZ type solid sensor; the heating relay (14) is electrically connected to the power module (3), and the heating element is electrically connected to the heating relay (14) via an aviation plug (6).

3. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 1, characterized in that: The signal amplification module comprises an instrument amplifier (8), an operational amplifier (9) and a feedback resistor (18); the operational amplifier (9) is electrically connected to the instrument amplifier (8) to form a two-stage amplification circuit, and the feedback resistor (18) is an adjustable resistor and is electrically connected to the operational amplifier (9) to form a variable gain amplification circuit.

4. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 3, characterized in that: The operational amplifier (9) is a differential amplifier.

5. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 1, characterized in that: The portable electrochemical gas detection device further comprises a display module (4); an opening for assembling the display module (4) is provided on the housing; the display module (4) is electrically connected to a micro control unit (7) via a serial port.

6. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 1, characterized in that: The portable electrochemical gas detection device further comprises a communication module (13), wherein the communication module (13) is electrically connected to the microcontroller unit (7), and the communication module (13) is used to establish a communication connection with an external data processing device and / or a data storage device.

7. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 6, characterized in that: The communication module (13) comprises a Bluetooth serial port and a UART interface.

8. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 1, characterized in that: The portable electrochemical gas detection device further comprises an indicator light, which is electrically connected to the micro control unit (7).

9. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 1, characterized in that: The housing comprises a front cover (2) and a rear cover (1) which are plug-fitted together; a plurality of mating shafts (16) are arranged on the inner side of the front cover (2), and the circuit board (15) is assembled inside the housing via the mating shafts (16).

10. A portable electrochemical gas detection device based on a YSZ solid-state sensor according to claim 9, characterized in that: There is a clearance fit between the circuit board (15) and the matching shaft (16).

Images