Gas detector based on MOS gas sensor and gas detection method

Abstract

The invention discloses a gas detector based on an MOS gas sensor and a gas detection method, and belongs to the field of gas detection. The gas detector comprises a gas sensor adapter plate, an MOS gas sensor, a display screen, a key panel and a gas detection circuit, a gas sensor socket is fixed on the gas sensor adapter plate, and different types of MOS gas sensors are detachably embedded in the gas sensor socket; the MOS gas sensor is used for detecting to-be-detected gas in the environment and generating response data; the gas detection circuit receives and processes the response data, and obtains the measurement concentration of the gas to be detected according to a preset response-concentration calibration relational expression; the key panel is used for setting a working detection mode and heating parameters of the MOS gas sensor, and the display screen is used for displaying the measured concentration of gas to be detected. And the function of detecting the concentrations of different gases with relatively low cost and power consumption in a simple and complex environment is realized.

Description

Technical Field

[0001] The present invention belongs to the technical field of gas detection, and more specifically, relates to a gas detector and a gas detection method based on a MOS gas sensor. Background Art

[0002] A gas sensor is a device that can convert gas signals in the environment into electrical signals for output. Compared with other methods for detecting gas pollutants such as gas chromatography-mass spectrometry, ion mobility spectrometry, infrared spectroscopy, surface acoustic wave method and piezoelectric optical method, gas sensors have the advantages of simple operation, low price, portability and easy integration. Therefore, they have been widely used in such fields as automobile exhaust emission detection, indoor and outdoor air pollutant detection, and leakage monitoring of toxic and harmful gases in industrial production. Metal oxide semiconductor (MOS) gas sensors are the most mainstream type of gas sensors currently in commercial use. Their detection principle is that when gas molecules interact with sensitive materials on their surfaces, the resistance of the sensitive materials will change. The magnitude of resistance change is different for different concentrations. However, the initial value, variation range and optimal operating temperature of the resistance signal of MOS gas sensors of different materials and processes are inconsistent, and there are large differences. In other words, the signal processing circuits of different MOS gas sensors are different.

[0003] In addition, MOS gas sensors usually have disadvantages such as cross-sensitivity and weak anti-interference ability. In complex environments, when a single MOS gas sensor is used for gas detection, it is often susceptible to interference from mixed gases and causes qualitative errors and quantitative inaccuracies. In order to improve the cross-sensitivity problem of MOS gas sensors and enable them to be applied to gas detection in complex environments, many methods have been proposed. One method is to use multiple MOS gas sensors to build an array and combine it with a pattern recognition algorithm to analyze the mixed gas, such as the FOX6000 product of Alpha, France. Although this can meet the detection requirements in some occasions, it will increase the instrument size, heating power consumption and cost compared to a single sensor solution, and it will also bring cumbersome operations when the gas sensor needs to be replaced due to environmental changes. Another method is to dynamically temperature modulate the MOS gas sensor to increase the dimension of the signal to obtain more response information. Although this method also requires the combination of complex recognition algorithms, it can greatly reduce the number of gas sensors required, even to a single one.

[0004] In real-world applications, different scenarios require different target gases to be detected, and users need to frequently change different types of portable detection instruments. When the environmental atmosphere becomes complex, the cost of existing sensor array-based solutions increases significantly, and their environmental applicability is poor. Currently, there is a lack of a low-cost portable universal instrument that can detect gas in simple and complex environments. Therefore, it is of great significance to design a low-cost portable universal gas detector that can detect different types of gases in different environments. Summary of the invention

[0005] In view of the defects of the related art, the purpose of the present invention is to provide a gas detector and a gas detection method based on a MOS gas sensor, aiming to solve the problem of frequent replacement of the detector when the target gas to be detected is different.

[0006] To achieve the above-mentioned object, in a first aspect, the present invention provides a gas detector based on a MOS gas sensor, comprising: a gas sensor adapter board, a MOS gas sensor, a display screen, a key panel and a gas detection circuit;

[0007] A gas sensor socket is fixedly arranged on the gas sensor adapter board, and the gas sensor socket is used for detachably inserting different types of MOS gas sensors;

[0008] The MOS gas sensor is used to detect the gas to be tested in the environment, generate response data, and output it to the gas detection circuit through the gas sensor connection board;

[0009] The gas detection circuit is used to receive and process the response data of the MOS gas sensor, and obtain the measured concentration of the gas to be measured according to a preset response-concentration calibration relationship;

[0010] The gas detection circuit is also connected to a key panel and a display screen. The key panel is used to set the working detection mode and heating parameters of the MOS gas sensor, and the display screen is used to display the measured concentration of the gas to be detected.

[0011] Optionally, the gas detection circuit includes a power supply and management module, a sensor driving module, a signal acquisition module, a signal conditioning module, an analog-to-digital conversion module, a single-chip computer system, an output module and a data storage module;

[0012] The power supply and management module is connected to other modules in the gas detection circuit to provide power to each module;

[0013] The sensor driving module is connected to the MOS gas sensor and is used to provide a working voltage for the MOS gas sensor according to the set working detection mode and heating parameters;

[0014] The signal acquisition module is used to match the resistance of the MOS gas sensor and adjust the response signal range generated by the MOS gas sensor;

[0015] The signal conditioning module is used to collect the response signal data generated by the MOS gas sensor and perform signal processing;

[0016] The analog-to-digital conversion module is used to convert the analog electrical signal in the processed response signal data into a digital signal that can be received and processed by the single-chip microcomputer;

[0017] The single-chip computer system is used to analyze and calculate the collected digital signal, obtain the concentration of the gas to be measured according to the preset response-concentration calibration relationship, and output the display signal of the concentration of the gas to be measured to the display screen through the output module for display;

[0018] The data storage module is used to store data generated by the single chip computer system.

[0019] Optionally, the gas detection circuit further includes a key module and a serial communication module;

[0020] The button module is used to set the working detection mode and heating parameters of the MOS gas sensor, and is also used in combination to set the number of stored response data;

[0021] The serial communication module is used for data transmission between an external computer and the single-chip microcomputer system, and for transplanting a gas calibration or identification algorithm to the single-chip microcomputer system to detect the concentration of the gas to be tested.

[0022] Optionally, the sensor driving circuit module includes a voltage reference chip, an operational amplifier circuit and a triode;

[0023] The voltage reference chip is used to provide an excitation voltage for the MOS gas sensor;

[0024] The operational amplifier circuit is connected to the triode and is used to apply a heating voltage to the MOS gas sensor.

[0025] Optionally, the signal acquisition module includes a matching resistor, a relay and a single-chip microcomputer;

[0026] One end of the MOS gas sensor is connected to the voltage reference chip to receive the excitation voltage, and the other end is connected in series with the matching resistor, and the other end of the matching resistor is grounded to form a loop;

[0027] The single chip microcomputer controls different relays to select different matching resistors to be connected to the loop, so as to adjust the response signal range generated by the MOS gas sensor.

[0028] Optionally, the gas detector further includes a buzzer and an LED light, and the buzzer and the LED light are connected to the output module;

[0029] The single chip microcomputer system is also used to generate an acoustic, optical and vibration alarm signal when the concentration of the gas to be measured reaches a set alarm value, and start the buzzer and LED light through the output module.

[0030] Optionally, the gas detector further comprises a housing, a sensor protection cover and an embedded locking nut;

[0031] The gas sensor adapter plate is fixed in the sensor protection cover, and the sensor protection cover is detachably fixed to the housing through the embedded locking nut;

[0032] The housing is provided with a display screen groove and a film panel groove, wherein the film panel groove is provided above the display screen groove; the display screen is embedded in the display screen groove, and the key panel is embedded and glued in the film panel groove;

[0033] A screw hole is provided in the shell, and the gas detection circuit is fixed in the shell by screws.

[0034] In a second aspect, the present invention further provides a gas detection method based on a MOS gas sensor, which is applied to a gas detector as described in any one of the first aspects, comprising:

[0035] S1. According to the type of gas to be tested, select the corresponding MOS gas sensor and insert it into the gas sensor socket of the gas detector;

[0036] S2. Set the working detection mode and heating parameters of the gas detector according to the complexity of the environment in which the gas to be detected is located;

[0037] S3. Placing the gas detector in a gas environment to be tested, starting the MOS gas sensor to detect the gas to be tested, and obtaining the measured concentration of the target gas through a pre-acquired signal response-concentration calibration relationship.

[0038] Optionally, the setting of the working detection mode and heating parameters of the gas detector according to the complexity of the environment in which the gas to be detected is located includes:

[0039] If the environment of the gas to be tested is a single gas environment, the constant temperature detection working detection method is adopted;

[0040] If the environment in which the gas to be tested is located is a complex gas environment containing interfering gases, the variable temperature detection working detection method is adopted.

[0041] Optionally, the signal response-concentration calibration relationship is obtained according to the following steps:

[0042] Select the corresponding MOS gas sensor according to the type of target gas and insert it into the body sensor socket of the gas detector;

[0043] Set the working detection mode and heating parameters of the gas detector according to the environment where the target gas is located;

[0044] Exposing the gas detector to target gases of different concentrations for multiple tests and storing response data;

[0045] Adjusting the heating parameters, using the detector to repeatedly test the target gas under different heating parameters, and storing the response data in sequence;

[0046] Feature extraction is performed on the response data, and combined with the concentration data of the target gas, a response signal-concentration calibration relationship corresponding to the target gas is obtained.

[0047] Compared with the prior art, the above technical solution conceived by the present invention can achieve the following beneficial effects:

[0048] 1. The present invention provides a gas detector based on a MOS gas sensor. Since the MOS gas sensor responds differently to different gases at the same temperature and responds differently to the same gas at different temperatures, the embodiment of the present invention can detachably insert different types of gas sensors by fixing a gas sensor socket on a gas sensor adapter board, allowing the user to replace different MOS gas sensors on the same instrument, which can be suitable for different gas detections. At the same time, by setting a constant temperature working detection mode or a variable temperature working detection mode, as well as corresponding heating parameters, the detector can detect different gases of different concentrations at a relatively low cost and power consumption in a variety of simple and complex environments, and at the same time has the characteristics of low cost and portability, and has great application prospects.

[0049] 2. The present invention provides a gas detector based on a MOS gas sensor. Different working detection modes are selected in different gas environments to be tested, and corresponding heating parameters are matched. The adjustable design of the heating parameters ensures that the MOS gas sensor can operate under optimal temperature conditions. The automatic switching design of the matching resistors in the detection circuit ensures that the detector can accurately collect the size and changes of different resistance signals of the MOS gas sensor. The operating steps of the gas detector are simplified, and the detection accuracy of the gas detector is improved.

[0050] 3. The present invention provides a gas detection method based on a MOS gas sensor, by pre-detecting different target gases multiple times at different concentrations to obtain response signal-concentration calibration equations corresponding to different types of gases; therefore, when using a gas detector based on a MOS gas sensor to detect gas concentration, it is only necessary to select a suitable gas sensor according to the type of gas to be detected and insert it into the gas sensor socket of the gas detector, thereby realizing the function of detecting different gases of different concentrations at a lower cost and power consumption in a variety of simple and complex environments. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0052] Figure 2 This is a diagram showing the structure of the gas detection circuit of the present invention.

[0053] The reference numerals in the above drawings are:

[0054] 100. Key panel, 200. Display screen, 300. Shell, 300-1. Upper shell, 300-2. Inside of lower shell, 400. Gas detection circuit, 500. Embedded locking nut, 600. Gas sensor adapter board, 700. MOS gas sensor, 800. Sensor protection cover. DETAILED DESCRIPTION

[0055] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0056] The contents involved in the above embodiment are described below in conjunction with a preferred embodiment.

[0057] Embodiment 1

[0058] like Figure 1 As shown, the present invention provides a gas detector based on a MOS gas sensor, comprising: a gas sensor adapter board 600, a MOS gas sensor 700, a display screen 200, a key panel 100 and a gas detection circuit 400;

[0059] The gas sensor adapter plate 600 is fixedly provided with a gas sensor socket, and the gas sensor socket is used for detachably inserting different types of MOS gas sensors 700;

[0060] The MOS gas sensor 700 is used to detect the gas to be tested in the environment, generate response data, and output it to the gas detection circuit 400 through the gas sensor connection board 600;

[0061] The gas detection circuit is used to receive and process the response data of the MOS gas sensor, and obtain the measured concentration of the gas to be measured according to a preset response-concentration calibration relationship;

[0062] The gas detection circuit 400 is also connected to the key panel 100 and the display screen 200. The key panel 100 is used to set the working detection mode and heating parameters of the MOS gas sensor 700, and the display screen 200 is used to display the measured concentration of the gas to be detected.

[0063] Among them, the gas sensor adapter board 600 is connected to the gas detection circuit 400 through the adapter board cable; different MOS gas sensors 700 can be selected for use according to the type of target response gas, and different types of adapter boards can be designed to adapt to MOS gas sensors with different packaging types.

[0064] Since the MOS gas sensor responds differently to different gases at the same temperature, and responds differently to the same gas at different temperatures, in a simple atmosphere (single gas), only constant temperature detection is required, and the concentration can be inferred from the concentration-response relationship; in a complex atmosphere (multiple atmospheres), due to the presence of interfering gases, the concentration-response relationship obtained by constant temperature detection cannot be directly applied. At this time, variable temperature detection is performed, and the sensor's response curve will contain more information features. After algorithm processing, a new concentration-response relationship can be obtained, thereby knowing the gas type and concentration and achieving detection.

[0065] Optionally, the gas detector further includes a housing 300, a sensor protection cover 800 and an embedded locking nut 500;

[0066] The gas sensor adapter plate 600 is fixed in the sensor protection cover 800, and the sensor protection cover 800 is detachably fixed to the housing 300 through the embedded locking nut 500;

[0067] The housing 300 is provided with a display screen groove and a film panel groove, wherein the film panel groove is provided above the display screen groove; the display screen 200 is embedded in the display screen groove, and the key panel 100 is embedded and glued in the film panel groove;

[0068] The housing 300 is provided with screw holes, and the gas detection circuit 400 is fixed in the housing 300 by screws.

[0069] The upper shell 300-1 of the housing 300 is provided with a display screen groove and a film panel groove, and the lower shell 300-2 is provided with screw holes. The display screen 200 is connected to the gas detection circuit 400 by a cable; the key panel 100 is pressed against the display screen 200 and is connected to the gas detection circuit 400 by a cable of the key panel.

[0070] The embedded locking nut 500 is fixed in the housing 300, and one end of the sensor protection cover 800 is a threaded structure, which is detachably fixed to the housing 300 through the embedded locking nut 500, thereby forming a fixed connection structure between the gas sensor and the housing.

[0071] The gas sensor can be disassembled and assembled only in the sensor protective cover 800 or between the sensor protective cover 800 and the housing 300, so that the disassembly and assembly operation can be realized very conveniently; specifically, when it is necessary to detect different target gases on site by replacing different MOS gas sensors, if the sensor package is the same as the existing sensor package, then the sensor protective cover 800 can be opened and the MOS gas sensor 700 can be directly replaced; if the sensor package is different from the existing sensor package, the sensor protective cover 800 can be removed, and the new MOS gas sensor 700 and the gas sensor adapter plate 600 can be replaced, and then the sensor protective cover 800 can be fixed on the housing, so that the gas sensor can be replaced quickly. Select the working mode of constant temperature or variable temperature detection, set the appropriate heating parameters, and then combine the corresponding calibration or pattern recognition algorithm to realize the detection of different target gases in a variety of simple and complex environments.

[0072] Optionally, the gas detection circuit includes a power supply and management module, a sensor driving module, a signal acquisition module, a signal conditioning module, an analog-to-digital conversion module, a single-chip computer system, an output module and a data storage module;

[0073] The power supply and management module is connected to other modules in the gas detection circuit to provide power to each module;

[0074] The sensor driving module is connected to the MOS gas sensor and is used to provide a working voltage for the MOS gas sensor according to the set working detection mode and heating parameters;

[0075] The signal acquisition module is used to match the resistance of the MOS gas sensor and adjust the response signal range generated by the MOS gas sensor;

[0076] The signal conditioning module is used to collect the response signal data generated by the MOS gas sensor and perform signal processing;

[0077] The analog-to-digital conversion module is used to convert the analog electrical signal in the processed response signal data into a digital signal that can be received and processed by the single-chip microcomputer;

[0078] The single-chip computer system is used to analyze and calculate the collected digital signal, obtain the concentration of the gas to be measured according to the preset response-concentration calibration relationship, and output the display signal of the concentration of the gas to be measured to the display screen through the output module for display;

[0079] The data storage module is used to store data generated by the single chip computer system.

[0080] Among them, the power supply and management module supplies power to the sensor drive circuit module signal acquisition module, signal conditioning module, analog-to-digital conversion module, single-chip computer system, key module, output module, data storage module and serial communication module through the lithium battery, and manages and controls the voltage and current when the lithium battery is charged through the charging management chip. Specifically, the power supply and management module includes a 12V lithium battery, a primary voltage regulator chip, a secondary voltage regulator chip, a charge pump chip and a charging management chip; the 12V lithium battery passes through the primary voltage regulator chip to obtain a primary voltage regulator positive voltage of 5V, and the primary voltage regulator positive voltage passes through the charge pump chip and the secondary voltage regulator chip to obtain a primary voltage regulator negative voltage of -5V and a secondary voltage regulator voltage of 3.3V respectively. The lithium battery voltage, the primary voltage regulator positive voltage, the primary voltage regulator negative voltage and the secondary voltage regulator voltage jointly power various chips and op amps in the detector circuit, and the charging management chip controls the voltage and current when the lithium battery is charged.

[0081] Optionally, the sensor driving circuit module includes a voltage reference chip, an operational amplifier circuit and a triode;

[0082] The voltage reference chip is used to provide an excitation voltage for the MOS gas sensor;

[0083] The operational amplifier circuit is connected to the triode and is used to apply a heating voltage to the MOS gas sensor.

[0084] Specifically, the voltage reference chip provides an excitation voltage for the MOS gas sensor, the operational amplifier circuit is connected to the built-in DAC peripheral of the microcontroller to adjust the value range of the heating voltage, and finally the operational amplifier circuit is connected to the transistor to amplify the heating current to form a sensor drive circuit module; the built-in DAC, timer and DMA peripheral of the microcontroller can be used to realize heating methods with different waveforms (sine wave, square wave and triangle wave) and different frequencies; constant temperature or variable temperature testing can be selected according to the actual environment.

[0085] Optionally, the signal acquisition module includes a matching resistor, a relay and a single-chip microcomputer;

[0086] One end of the MOS gas sensor is connected to the voltage reference chip to receive the excitation voltage, and the other end is connected in series with the matching resistor, and the other end of the matching resistor is grounded to form a loop;

[0087] The single chip microcomputer controls different relays to select different matching resistors to be connected to the loop, so as to adjust the response signal range generated by the MOS gas sensor.

[0088] The signal acquisition module includes a matching resistor, a relay, a triode, a diode and a single-chip microcomputer; one end of the MOS gas sensor is connected to an excitation voltage, and the other end is connected in series with a matching resistor, and the other end of the matching resistor is grounded to form a loop. The single-chip microcomputer automatically controls different triodes to conduct according to the voltage-dividing signal of the matching resistor, and then controls different relays to conduct, so as to select different matching resistors to obtain a signal in a suitable range, avoid the occurrence of signal reflection, and improve the detection accuracy and concentration range. The diode is connected to both ends of the relay coil to prevent the back electromotive force generated by the disconnection of the relay coil from damaging the single-chip microcomputer.

[0089] Furthermore, the signal conditioning circuit includes an operational amplifier, a resistor, and a capacitor; the resistor, the capacitor and the operational amplifier are connected to form a third-order full-pole active filter circuit to filter out high-frequency signals from the collected voltage signal; the operational amplifier adopts a JFET type operational amplifier and is connected in a voltage follower structure to isolate the front-end and back-end circuits and reduce the impact of the input signal on the back-end analog-to-digital conversion.

[0090] Furthermore, the analog-to-digital conversion circuit includes an analog-to-digital conversion chip, a resistor, a capacitor, and a diode; the analog-to-digital conversion chip converts the input analog signal into a digital output signal, and transmits it to the single-chip microcomputer system via the SPI bus for subsequent processing.

[0091] Furthermore, the single-chip microcomputer system includes a single-chip microcomputer, a crystal oscillator, a capacitor, a power supply, and a resistor; the pins of the single-chip microcomputer are connected to the crystal oscillator, the capacitor, the resistor, and the power supply so that the single-chip microcomputer can analyze and calculate the collected signals, and obtain information such as the type and concentration of the detected gas according to the corresponding gas identification and calibration algorithm.

[0092] Furthermore, the data storage module includes an SD card, a resistor and an SD card holder; the SD card stores information related to gas detection, including heating waveform, amplitude voltage, detection resistance, gas concentration, etc.

[0093] Optionally, the gas detection circuit further includes a key module and a serial communication module;

[0094] The button module is used to set the working detection mode and heating parameters of the MOS gas sensor, and is also used in combination to set the number of stored response data;

[0095] The serial communication module is used for data transmission between an external computer and the single-chip microcomputer system, and for transplanting a gas calibration or identification algorithm to the single-chip microcomputer system to detect the concentration of the gas to be tested.

[0096] Use the up, down, left, right and confirmation keys to set the digital number of the data storage file, select the constant temperature or variable temperature test working mode of the detector, adjust the heating parameters of the detector such as waveform type, amplitude and frequency, etc., the power on and off keys control the power on and off of the detector, and the reset key restores the detector to a stable starting state.

[0097] The serial communication module includes a USB chip, a USB interface, a resistor, a capacitor and a diode; it is connected to a computer via a USB port to perform operations such as data transmission, calibration or identification algorithm program update.

[0098] Optionally, the gas detector further includes a buzzer and an LED light, and the buzzer and the LED light are connected to the output module;

[0099] The single chip microcomputer system is also used to generate an acoustic, optical and vibration alarm signal when the concentration of the gas to be measured reaches a set alarm value, and start the buzzer and LED light through the output module.

[0100] The display screen is an LCD screen, which mainly displays the working status of the detector and gas detection information, including heating waveform, amplitude, waveform frequency, sensor resistance, gas type and gas concentration, etc. The buzzer and LED light indicate whether the gas exceeds the limit. The output module is used to receive display signals and sound, light and vibration alarm signals, and activate the buzzer and LED light to display information and sound and light alarms, and can also activate the display screen to display relevant alarm information.

[0101] In the embodiment of the present invention, a gas sensor socket is fixedly provided on the gas sensor adapter plate, so that different types of gas sensors can be detachably inserted, allowing the user to replace different MOS gas sensors on the same instrument, which can be suitable for different gas detections; at the same time, by setting a constant temperature working detection mode or a variable temperature working detection mode, and corresponding heating parameters, the detector can detect different gases of different concentrations at a lower cost and power consumption in a variety of simple and complex environments. The problem of frequent replacement of the detector when the target gas to be detected is solved. It can realize rapid detection of gas concentration in different environments and with different gases to be tested, while having the characteristics of low cost and portability, and has great application prospects.

[0102] Embodiment 2

[0103] The present invention further provides a gas detection method based on a MOS gas sensor, which is applied to a gas detector as described in any one of the first embodiments, comprising:

[0104] S1. According to the type of gas to be tested, select the corresponding MOS gas sensor and insert it into the gas sensor socket of the gas detector;

[0105] S2. Set the working detection mode and heating parameters of the gas detector according to the complexity of the environment in which the gas to be detected is located;

[0106] S3. Placing the gas detector in a gas environment to be tested, starting the MOS gas sensor to detect the gas to be tested, and obtaining the measured concentration of the target gas through a pre-acquired signal response-concentration calibration relationship.

[0107] Optionally, the setting of the working detection mode and heating parameters of the gas detector according to the complexity of the environment in which the gas to be detected is located includes:

[0108] If the environment of the gas to be tested is a single gas environment, the constant temperature detection working detection method is adopted;

[0109] If the environment in which the gas to be tested is located is a complex gas environment containing interfering gases, the variable temperature detection working detection method is adopted.

[0110] Optionally, the signal response-concentration calibration relationship is obtained according to the following steps:

[0111] Select the corresponding MOS gas sensor according to the type of target gas and insert it into the body sensor socket of the gas detector;

[0112] Set the working detection mode and heating parameters of the gas detector according to the environment where the target gas is located;

[0113] Exposing the gas detector to target gases of different concentrations for multiple tests and storing response data;

[0114] Adjusting the heating parameters, using the detector to repeatedly test the target gas under different heating parameters, and storing the response data in sequence;

[0115] Feature extraction is performed on the response data, and combined with the concentration data of the target gas, a response signal-concentration calibration relationship corresponding to the target gas is obtained.

[0116] Before using a gas detector based on a MOS gas sensor for gas detection, it is necessary to perform multiple tests on different target gases at different concentrations in advance to obtain the response signal-concentration calibration relationship corresponding to different types of gases.

[0117] In a specific embodiment, the detection of nitrogen dioxide in a simple air environment (without other interfering gases) is taken as an example for further explanation:

[0118] For the detection of nitrogen dioxide in a simple air environment, a high-sensitivity and high-stability MOS nitrogen dioxide sensor with 0.25% Sb-doped SnO2-Pd as the gas sensitive material is used. After installing the MOS gas sensor, turn on the power, and then select constant temperature detection through key input. The heating voltage is set to 5V, and the corresponding operating temperature is 240℃. After the MOS gas sensor is preheated and stabilized, the resistance value of the detector exposed to different concentrations of nitrogen dioxide standard gas is tested and stored. The stored response data is imported into the computer, and the data is curve-fitted to obtain the response-concentration calibration relationship, and then the calibration relationship is transplanted to the microcontroller through the serial port.

[0119] Select a MOS nitrogen dioxide sensor and install it in the detector through the sensor connection board; place the detector in the atmosphere of the gas to be tested, the gas detection circuit receives and processes the MOS gas sensor sensing signal according to the calibration relationship, and displays the detection result through an output module such as an LCD display.

[0120] In another specific embodiment, the detection of hydrogen sulfide in a complex air environment (with the presence of ammonia interfering gas) is taken as an example for further explanation:

[0121] For the detection of hydrogen sulfide in complex air environments, a commercial MOS sensor TGS2602 with high response sensitivity to hydrogen sulfide and ammonia is used. After installing the MOS gas sensor, turn on the power, select the variable temperature detection mode, adjust the heating waveform, amplitude and frequency through the buttons. After determining the heating parameters, expose the detector to the air for a certain period of time, save the response of the detector in the air under the heating parameters, then test and save the response of the detector in hydrogen sulfide standard gas with different concentrations under the heating parameters, and then test and save the response of the detector in ammonia standard gas with different concentrations under the heating parameters. Adjust the heating parameters, repeat the above steps, and record and store the test data of the detector for air, hydrogen sulfide and ammonia under different heating parameters in turn by number. Import the stored test data into the computer, extract the features of the data, select the classification algorithm to train the gas recognition model, and then transplant the model into the single-chip microcomputer.

[0122] Select MOS sensor TGS2602 and install it into the detector through the sensor connecting board; place the detector in the atmosphere of the gas to be tested, the gas detection circuit receives and processes the MOS gas sensor sensing signal according to the gas identification model, and displays the detection result through output modules such as LCD display.

[0123] The gas detection method of the embodiment of the present invention, when using a gas detector based on a MOS gas sensor to detect gas concentration, only needs to select a suitable gas sensor according to the type of gas to be tested and insert it into the gas sensor socket of the gas detector. It can realize the function of detecting different gases of different concentrations at low cost and power consumption in a variety of simple and complex environments.

[0124] It will be easily understood by those skilled in the art that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A gas detector based on MOS gas sensor, characterized in that: include: Gas sensor adapter board, MOS gas sensor, display screen, key panel and gas detection circuit; A gas sensor socket is fixedly arranged on the gas sensor adapter board, and the gas sensor socket is used for detachably inserting different types of MOS gas sensors; The MOS gas sensor is used to detect the gas to be tested in the environment, generate response data, and output it to the gas detection circuit through the gas sensor connection board; The gas detection circuit is used to receive and process the response data of the MOS gas sensor, and obtain the measured concentration of the gas to be measured according to a preset response-concentration calibration relationship; The gas detection circuit is also connected to a key panel and a display screen. The key panel is used to set the working detection mode and heating parameters of the MOS gas sensor, and the display screen is used to display the measured concentration of the gas to be detected.

2. The gas detector according to claim 1, characterized in that: The gas detection circuit includes a power supply and management module, a sensor driving module, a signal acquisition module, a signal conditioning module, an analog-to-digital conversion module, a single-chip computer system, an output module and a data storage module; The power supply and management module is connected to other modules in the gas detection circuit to provide power to each module; The sensor driving module is connected to the MOS gas sensor and is used to provide a working voltage for the MOS gas sensor according to the set working detection mode and heating parameters; The signal acquisition module is used to match the resistance of the MOS gas sensor and adjust the response signal range generated by the MOS gas sensor; The signal conditioning module is used to collect the response signal data generated by the MOS gas sensor and perform signal processing; The analog-to-digital conversion module is used to convert the analog electrical signal in the processed response signal data into a digital signal that can be received and processed by the single-chip microcomputer; The single-chip computer system is used to analyze and calculate the collected digital signal, obtain the concentration of the gas to be measured according to the preset response-concentration calibration relationship, and output the display signal of the concentration of the gas to be measured to the display screen through the output module for display; The data storage module is used to store data generated by the single chip computer system.

3. The gas detector according to claim 2, characterized in that: The gas detection circuit also includes a key module and a serial communication module; The button module is used to set the working detection mode and heating parameters of the MOS gas sensor, and is also used in combination to set the number of stored response data; The serial communication module is used for data transmission between an external computer and the single-chip microcomputer system, and for transplanting a gas calibration or identification algorithm to the single-chip microcomputer system to detect the concentration of the gas to be tested.

4. The gas detector according to claim 2, characterized in that: The sensor driving circuit module includes a voltage reference chip, an operational amplifier circuit and a triode; The voltage reference chip is used to provide an excitation voltage for the MOS gas sensor; The operational amplifier circuit is connected to the triode and is used to apply a heating voltage to the MOS gas sensor.

5. The gas detector according to claim 2, characterized in that: The signal acquisition module includes a matching resistor, a relay and a single chip microcomputer; One end of the MOS gas sensor is connected to the voltage reference chip to receive the excitation voltage, and the other end is connected in series with the matching resistor, and the other end of the matching resistor is grounded to form a loop; The single chip microcomputer controls different relays to select different matching resistors to be connected to the loop, so as to adjust the response signal range generated by the MOS gas sensor.

6. The gas detector according to claim 1, characterized in that: The gas detector also includes a buzzer and an LED light, and the buzzer and the LED light are connected to the output module; The single chip microcomputer system is also used to generate an acoustic, optical and vibration alarm signal when the concentration of the gas to be measured reaches a set alarm value, and start the buzzer and LED light through the output module.

7. The gas detector according to claim 1, characterized in that: The gas detector also includes a housing, a sensor protection cover and an embedded locking nut; The gas sensor adapter plate is fixed in the sensor protection cover, and the sensor protection cover is detachably fixed to the housing through the embedded locking nut; The housing is provided with a display screen groove and a film panel groove, wherein the film panel groove is provided above the display screen groove; the display screen is embedded in the display screen groove, and the key panel is embedded and glued in the film panel groove; A screw hole is provided in the shell, and the gas detection circuit is fixed in the shell by screws.

8. A gas detection method based on a MOS gas sensor, applied to a gas detector as claimed in any one of claims 1 to 7, characterized in that: include: S1. According to the type of gas to be tested, select the corresponding MOS gas sensor and insert it into the gas sensor socket of the gas detector; S2. Set the working detection mode and heating parameters of the gas detector according to the complexity of the environment in which the gas to be detected is located; S3. Placing the gas detector in a gas environment to be tested, starting the MOS gas sensor to detect the gas to be tested, and obtaining the measured concentration of the target gas through a pre-acquired signal response-concentration calibration relationship.

9. The gas detection method according to claim 8, characterized in that: The method of setting the working detection mode and heating parameters of the gas detector according to the complexity of the environment in which the gas to be detected is located includes: If the environment of the gas to be tested is a single gas environment, the constant temperature detection working detection method is adopted; If the environment in which the gas to be tested is located is a complex gas environment containing interfering gases, the variable temperature detection working detection method is adopted.

10. The gas detection method according to claim 8, characterized in that: The signal response-concentration calibration relationship is obtained according to the following steps: Select the corresponding MOS gas sensor according to the type of target gas and insert it into the body sensor socket of the gas detector; Set the working detection mode and heating parameters of the gas detector according to the environment where the target gas is located; Exposing the gas detector to target gases of different concentrations for multiple tests and storing response data; Adjusting the heating parameters, using the detector to repeatedly test the target gas under different heating parameters, and storing the response data in sequence; Feature extraction is performed on the response data, and combined with the concentration data of the target gas, a response signal-concentration calibration relationship corresponding to the target gas is obtained.

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