Method for optimizing performance of three-electrode gas sensor, method for preparing three-electrode gas sensor, and array of three-electrode gas sensors

Abstract

The application relates to a performance optimization method and preparation method of a three-electrode gas sensor and a three-electrode gas sensor array. Gases in the three-electrode gas sensor are discharged by a vacuum pump to reach a vacuum state, then a mixed gas with a preset concentration is introduced into the three-electrode gas sensor, and the gas supply is stopped when the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, and a first current value output by the three-electrode gas sensor at this time is recorded; the concentration of the preset gas in the three-electrode gas sensor is adjusted, and a second current value output by the three-electrode gas sensor at this time is recorded; the sensitivity corresponding to the interelectrode distance is determined according to the first current value, the concentration of the preset gas corresponding to the first current value, the second current value and the concentration of the preset gas corresponding to the second current value; the interelectrode distance is adjusted until the obtained sensitivity is a maximum sensitivity value, and the interelectrode distance corresponding to the maximum sensitivity value is determined as a target interelectrode distance of the three-electrode gas sensor.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of three-electrode gas sensor, in particular to a performance optimization method of three-electrode gas sensor, a preparation method of three-electrode gas sensor and a three-electrode gas sensor array. BACKGROUND

[0002] SF6 (sulfur hexafluoride) gas is widely used in electrical equipment, such as high-voltage switch, high-voltage transformer, circuit breaker, high-voltage transmission equipment, electrical enclosed combination capacitor and mutual inductor, because of its excellent insulation performance, arc extinguishing ability and stable chemical properties. However, in the case of faults such as device insulation damage, high-voltage arc discharge and device manufacturing defects, the electrical equipment will ionize SF6 gas and generate various low-fluorine sulfides under partial discharge or overheating. Therefore, by monitoring and detecting the gas species and concentration inside the electrical equipment, the device faults and abnormalities can be found as soon as possible.

[0003] In the conventional technology, the gas sensor is used to detect the gas species and concentration inside the electrical equipment. However, so far, there is no gas sensor that can detect in the mixed gas environment inside the electrical equipment. SUMMARY

[0004] Therefore, it is necessary to provide a performance optimization method of three-electrode gas sensor, a preparation method of three-electrode gas sensor and a three-electrode gas sensor array, which can detect gas in a mixed gas environment.

[0005] In a first aspect, the present application provides a performance optimization method of three-electrode gas sensor, the three-electrode gas sensor comprising a cathode, an extraction electrode and a collection electrode which are sequentially and spacedly stacked; the method comprising:

[0006] cyclically performing the following steps until the maximum sensitivity is determined, and taking the inter-electrode distance corresponding to the maximum sensitivity as the target inter-electrode distance of the three-electrode gas sensor:

[0007] evacuating the gas in the three-electrode gas sensor to a vacuum state based on a vacuum pump;

[0008] passing a mixed gas with a preset concentration into the three-electrode gas sensor until the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, and recording a first current value output by the three-electrode gas sensor;

[0009] adjusting the concentration of the preset gas in the three-electrode gas sensor, and recording a corresponding second current value; wherein the preset gas is any one of the mixed gas;

[0010] determine the sensitivity corresponding to the inter-electrode distance according to the first current value, the concentration of the preset gas corresponding to the first current value, the second current value, and the concentration of the preset gas corresponding to the second current value;

[0011] adjust the inter-electrode distance.

[0012] In one of the embodiments, the method further comprises:

[0013] obtain the calibration concentration values of the three-electrode gas sensor for the preset gas;

[0014] input the calibration concentration values into a preset concentration detection model to obtain actual concentration prediction values of each gas concentration corresponding to the calibration concentration values; the preset concentration detection model is a detection model of actual concentration prediction values corresponding to calibration concentration value samples obtained after training based on the calibration concentration value samples;

[0015] determine a gas concentration influence coefficient according to the actual concentration prediction values and the calibration concentration values;

[0016] correct each calibration concentration value of the three-electrode gas sensor according to the gas concentration influence coefficient.

[0017] In one of the embodiments, the determination of the preset concentration detection model comprises:

[0018] obtain calibration concentration value samples of the three-electrode gas sensor for different mixed gases to form a concentration data set; wherein the gas composition of the different mixed gases is the same, but the concentration of at least one gas in the different mixed gases is different;

[0019] determine the hidden layer node output, the output layer node output, and the error of the hidden layer and the output layer of the BP neural network based on the BP neural network, the initialized neurons, and the concentration data set;

[0020] update the weights and thresholds of the BP neural network according to the hidden layer node output, the output layer node output, and the error until a termination condition is reached; wherein the termination condition is that the error is less than a preset error or the number of training times is reached;

[0021] determine the trained BP neural network as the preset concentration detection model.

[0022] In one of the embodiments, the step of obtaining calibration concentration value samples of the three-electrode gas sensor for different mixed gases to form a concentration data set comprises:

[0023] obtain each calibration concentration value sample;

[0024] normalize each calibration concentration value sample to obtain the concentration data set.

[0025] In a second aspect, the application further provides a preparation method of a three-electrode gas sensor, comprising:

[0026] providing a collector, an extraction electrode and a cathode;

[0027] back hole etching is performed on the side of the cathode away from the extraction electrode to form a plurality of diffusion holes;

[0028] micropillar etching is performed on the side of the cathode close to the extraction electrode to form a plurality of first micropillars;

[0029] etching is performed on both sides of the extraction electrode to form a plurality of extraction holes and a plurality of second micropillars;

[0030] micropillar etching and groove etching are performed on the side of the collector close to the extraction electrode to form a plurality of third micropillars and a plurality of grooves; wherein the grooves are oppositely arranged with the extraction holes, and each third micropillar is arranged around each groove;

[0031] sputtering gold film on the surface of the cathode, the extraction electrode and the collector, respectively;

[0032] annealing the cathode, the extraction electrode and the collector in an annealing instrument;

[0033] based on the target electrode spacing, assembling the annealed cathode, extraction electrode and collector by using support columns; wherein the target electrode spacing is determined based on the performance optimization method of the three-electrode gas sensor;

[0034] bonding gold wires on the surface of the cathode, the extraction electrode and the collector, respectively, and packaging to make the gold wires as extraction leads to connect external systems.

[0035] In one embodiment, the above method further comprises:

[0036] sequentially plating aluminum film and gold film on the surface of the gold film to form a metal thick film structure.

[0037] In one embodiment, the packaging step comprises:

[0038] tinned iron material is used for packaging.

[0039] In one embodiment, when the mixed gas includes sulfur dioxide, carbon monoxide and hydrogen sulfide, the aperture of the diffusion hole is 1.0-4.0 mm;

[0040] The diameter of the first micropillar, the second micropillar and the third micropillar is 10-40 μm, the height is 50-100 μm, and the spacing is 20-60 μm;

[0041] The aperture of the extraction hole is 2.0-6.0 mm;

[0042] The length of the side of the groove is in the range of 1mm-8mm, and the depth of the groove is in the range of 200um-400um.

[0043] In one of the embodiments, the number of diffusion holes is in the range of 6-20; the number of lead-out holes is in the range of 6-20; and the number of grooves is in the range of 6-20.

[0044] In a third aspect, the application further provides a three-electrode gas sensor array, comprising: a first gas sensor, a second gas sensor and a third gas sensor, which are all prepared based on the preparation method of the three-electrode gas sensor.

[0045] The collecting electrode of the first gas sensor, the collecting electrode of the second gas sensor and the collecting electrode of the third gas sensor are on the same plane.

[0046] The preset gas corresponding to the first gas sensor is sulfur dioxide; the preset gas corresponding to the second gas sensor is carbon monoxide; and the preset gas corresponding to the third gas sensor is hydrogen sulfide.

[0047] The performance optimization method of the three-electrode gas sensor, the preparation method of the three-electrode gas sensor and the three-electrode gas sensor array, through the vacuum pump, the gas in the three-electrode gas sensor is discharged, so that the three-electrode gas sensor reaches a vacuum state, then the mixed gas of a preset concentration is introduced into the three-electrode gas sensor, at the same time, the internal pressure of the three-electrode gas sensor is detected, and the gas supply is stopped when the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, and the first current value output by the three-electrode gas sensor at this time is recorded; the concentration of the preset gas in the three-electrode gas sensor is adjusted, and the second current value output by the three-electrode gas sensor at this time is recorded, the sensitivity corresponding to the inter-electrode distance is determined according to the first current value, the concentration of the preset gas corresponding to the first current value, the second current value and the concentration of the preset gas corresponding to the second current value, the inter-electrode distance is adjusted until the obtained sensitivity is the maximum sensitivity, the inter-electrode distance corresponding to the maximum sensitivity is determined as the target inter-electrode distance of the three-electrode gas sensor, and the three-electrode gas sensor is prepared with the target inter-electrode distance, so as to detect the gas in the mixed gas environment, and the performance of the three-electrode gas sensor is optimized. BRIEF DESCRIPTION OF DRAWINGS

[0048] In order to more clearly illustrate the technical solutions in the embodiments of the application or the related art, the following will briefly introduce the drawings needed to be used in the description of the embodiments of the application or the related art. Obviously, the drawings in the following description are only some embodiments of the application, and for those skilled in the art, other related drawings can also be obtained without creative labor based on these drawings.

[0049] Figure 1Figure for application environment of performance optimization method of three-electrode gas sensor in one embodiment;

[0050] Figure 2 Flow chart for performance optimization method of three-electrode gas sensor in one embodiment;

[0051] Figure 3 Experimental curve figure for adjusting concentration of sulfur dioxide multiple times based on pulse excitation in one embodiment;

[0052] Figure 4 Experimental curve figure for adjusting concentration of hydrogen sulfide multiple times based on pulse excitation in one embodiment;

[0053] Figure 5 Experimental curve figure for adjusting concentration of carbon monoxide multiple times based on pulse excitation in one embodiment;

[0054] Figure 6 Experimental curve figure for adjusting concentration of sulfur dioxide multiple times based on direct current excitation in one embodiment;

[0055] Figure 7 Figure for electric field intensity of micro pillar tip under direct current excitation in one embodiment;

[0056] Figure 8 Figure for electric field intensity of micro pillar tip under pulse excitation in one embodiment;

[0057] Figure 9 Figure for electron density distribution of three-electrode gas sensor under direct current excitation in one embodiment;

[0058] Figure 10 Figure for electron density distribution of three-electrode gas sensor under pulse excitation in one embodiment;

[0059] Figure 11 Flow chart for preparation method of three-electrode gas sensor in one embodiment;

[0060] Figure 12 Structure figure of three-electrode gas sensor in one embodiment;

[0061] Figure 13 Cross-sectional view of three-electrode gas sensor in one embodiment;

[0062] Figure 14 Output of three-electrode gas sensor with packaging under power frequency electric field interference in one embodiment;

[0063] Figure 15 Output of three-electrode gas sensor without packaging under power frequency electric field interference in one embodiment;

[0064] Figure 16 Dynamic response characteristic curve one of a three-electrode gas sensor array in an embodiment;

[0065] Figure 17 Dynamic response characteristic curve two of a three-electrode gas sensor array in an embodiment;

[0066] Figure 18 Dynamic response characteristic curve three of a three-electrode gas sensor array in an embodiment. DETAILED DESCRIPTION

[0067] In order to make the purposes, technical solutions and advantages of the present application clearer, the present application is further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and not used to limit the present application.

[0068] The performance optimization method of the three-electrode gas sensor provided by the embodiments of the present application can be applied in the application environment as shown in Figure 1 The gas in the three-electrode gas sensor 104 is discharged by the vacuum pump 102, so that the inside of the three-electrode gas sensor 104 reaches a vacuum state, then the mixed gas with a preset concentration is introduced into the three-electrode gas sensor 104 through the aeration device 106, at the same time, the pressure sensor 108 is used to detect the internal pressure of the three-electrode gas sensor 104, and the gas supply is stopped when the internal pressure of the three-electrode gas sensor 104 reaches one standard atmosphere, and the first current value output by the three-electrode gas sensor 104 at this time is recorded; the concentration of the preset gas in the three-electrode gas sensor 104 is adjusted, and the second current value output by the three-electrode gas sensor 104 at this time is recorded, the sensitivity corresponding to the interelectrode distance is determined according to the first current value, the concentration of the preset gas corresponding to the first current value, the second current value, and the concentration of the preset gas corresponding to the second current value, the interelectrode distance is adjusted until the obtained sensitivity is the maximum sensitivity, the interelectrode distance corresponding to the maximum sensitivity is determined as the target interelectrode distance of the three-electrode gas sensor 104, and the three-electrode gas sensor 104 is prepared with the target interelectrode distance, so as to optimize the performance of the three-electrode gas sensor 104.

[0069] In an exemplary embodiment, as shown in Figure 2 A performance optimization method of a three-electrode gas sensor is provided, the three-electrode gas sensor comprising a cathode, an extraction electrode and a collection electrode which are sequentially and spacedly stacked; the method comprises:

[0070] The following steps are cyclically executed until the maximum sensitivity is determined in S200, and the interelectrode distance corresponding to the maximum sensitivity is taken as the target interelectrode distance of the three-electrode gas sensor:

[0071] S202, based on the vacuum pump, the gas in the three-electrode gas sensor is discharged to reach a vacuum state.

[0072] In order to improve the accuracy of the target electrode spacing, the electrode spacing determination step can be performed at room temperature. Further, in order to ensure the correct setting of the temperature, the temperature of the gas chamber in the three-electrode gas sensor can be set to room temperature.

[0073] S204, a mixed gas with a predetermined concentration is introduced into the three-electrode gas sensor until the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, and a first current value output by the three-electrode gas sensor is recorded.

[0074] Further, in order to ensure that the mixed gas introduced into the three-electrode gas sensor does not significantly affect the temperature of the gas chamber in the three-electrode gas sensor, the temperature of the mixed gas can be adjusted to room temperature before being introduced into the three-electrode gas sensor.

[0075] In the case where the prepared three-electrode gas sensor is used to measure the concentration of the mixed gas inside the electrical equipment, the mixed gas includes sulfur dioxide, carbon monoxide and hydrogen sulfide.

[0076] S206, adjust the concentration of the preset gas in the three-electrode gas sensor, and record the corresponding second current value; wherein the preset gas is any one of the mixed gas.

[0077] Part of the gas in the three-electrode gas sensor is discharged by the exhaust device, and the preset gas is introduced until the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, so as to realize the increase of the concentration of the preset gas. Correspondingly, after the exhaust device discharges part of the gas in the three-electrode gas sensor, the preset gas in the mixed gas is introduced into the three-electrode gas sensor until the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, so as to realize the decrease of the concentration of the preset gas.

[0078] S208, according to the first current value, the concentration of the preset gas corresponding to the first current value, the second current value, and the concentration of the preset gas corresponding to the second current value, determine the sensitivity corresponding to the electrode spacing.

[0079] According to the first current value and the second current value, the current difference value is determined, according to the concentration of the preset gas corresponding to the first current value and the concentration of the preset gas corresponding to the second current value, the gas concentration difference value is determined, and according to the ratio between the current difference value and the gas concentration difference value, the corresponding sensitivity under the electrode spacing can be determined.

[0080] Further, the preset gas concentration can be increased and / or decreased multiple times to determine multiple second current values, so as to perform multiple sensitivity calculations; in the presence of multiple second current values, the current difference value can be determined by the second current values corresponding to two different preset gas concentrations, and the gas concentration difference value can be determined according to the concentration of the preset gas corresponding to one of the second current values and the concentration of the preset gas corresponding to the other second current value, so as to determine the sensitivity.

[0081] After multiple calculations of different data, multiple sensitivities can be obtained, and after mean value calculation of the sensitivities, a sensitivity with smaller error can be finally determined.

[0082] As shown in Figure 3 , Figure 4 and Figure 5 , the experimental records for sulfur dioxide are shown in Figure 3 , Figure 4 the experimental records for hydrogen sulfide are shown in Figure 5 , and the experimental records for carbon monoxide are shown in Figure 3 , Figure 4 and Figure 5 , the forward stroke represents gradually increasing the preset gas concentration, and the return stroke represents gradually decreasing the preset gas concentration.

[0083] S210, adjusting the interelectrode distance.

[0084] The interelectrode distance is adjusted according to the sensitivity, so that the interelectrode distance corresponding to the maximum sensitivity is determined as the target interelectrode distance.

[0085] Specifically, the sensitivity obtained this time is compared with the sensitivity obtained last time, and the interelectrode distance is adjusted on the basis of the interelectrode distance corresponding to the greater sensitivity. If sensitivity A, sensitivity B and sensitivity C, wherein the interelectrode distance A corresponding to sensitivity A is between the interelectrode distance B corresponding to sensitivity B and the interelectrode distance C corresponding to sensitivity C, and sensitivity A is greater than sensitivity B and sensitivity C, then in this case, it can be considered that sensitivity A is the maximum sensitivity.

[0086] Further, in order to improve the accuracy of the three-electrode gas sensor, the interelectrode distance can be further adjusted in detail between the interelectrode distances corresponding to sensitivity B and sensitivity C, and the above-mentioned cycle is performed to determine a three-electrode gas sensor with better performance.

[0087] For example, in the case of a preset gas being sulfur dioxide, the target interelectrode distance can be determined as 80um; in the case of a preset gas being hydrogen sulfide, the target interelectrode distance can be determined as 90um; and in the case of a preset gas being carbon monoxide, the target interelectrode distance can be determined as 100um.

[0088] Therefore, the performance optimization method of the three-electrode gas sensor evacuates the gas in the three-electrode gas sensor by the vacuum pump, so that the three-electrode gas sensor reaches a vacuum state, then the mixed gas with a preset concentration is introduced into the three-electrode gas sensor, while the internal pressure of the three-electrode gas sensor is detected, and the gas supply is stopped when the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, and the first current value output by the three-electrode gas sensor at this time is recorded; the concentration of the preset gas in the three-electrode gas sensor is adjusted, and the second current value output by the three-electrode gas sensor at this time is recorded, and the sensitivity corresponding to the inter-electrode distance is determined according to the first current value, the concentration of the preset gas corresponding to the first current value, the second current value, and the concentration of the preset gas corresponding to the second current value, the inter-electrode distance is adjusted until the obtained sensitivity is the maximum sensitivity, and the inter-electrode distance corresponding to the maximum sensitivity is determined as the target inter-electrode distance of the three-electrode gas sensor, and the three-electrode gas sensor is prepared with the target inter-electrode distance, so as to detect the gas in the mixed gas environment, and the performance of the three-electrode gas sensor is optimized.

[0089] In an exemplary embodiment, the performance optimization method of the three-electrode gas sensor further comprises:

[0090] Obtaining a calibration concentration value of the preset gas for the three-electrode gas sensor.

[0091] Preparing the three-electrode gas sensor according to the determined target inter-electrode distance, and calibrating the concentration of the preset gas in the mixed gas based on the three-electrode gas sensor to determine the calibration concentration value.

[0092] Inputting the calibration concentration value into a preset concentration detection model to obtain actual concentration prediction values of each gas concentration corresponding to the calibration concentration value; the preset concentration detection model is a detection model of actual concentration prediction values corresponding to calibration concentration value samples obtained after training based on the calibration concentration value samples.

[0093] Determining a gas concentration influence coefficient according to the actual concentration prediction value and the calibration concentration value.

[0094] Correcting each calibration concentration value of the three-electrode gas sensor according to the gas concentration influence coefficient.

[0095] Since there may be certain errors in the gas concentration calibration based on the three-electrode gas sensor, the calibration concentration value is input into the preset concentration detection model to obtain the actual concentration prediction value corresponding to the calibration concentration value, and then the gas concentration influence coefficient is determined according to the actual concentration prediction value and the calibration concentration value. When calibrating the concentration of the preset gas in the mixed gas based on the three-electrode gas sensor again, the calibration concentration value obtained is corrected by using the above-mentioned gas concentration influence coefficient, thereby reducing the error and improving the accuracy of the data.

[0096] Further, one-to-one corresponding actual concentration prediction values can be determined based on the plurality of calibration concentration values and the preset concentration detection model, and then the gas concentration influence coefficients can be determined according to the calibration concentration values and the corresponding actual concentration prediction values. The gas concentration influence coefficients are subjected to mean value calculation, so as to determine a gas concentration influence coefficient with higher reliability, thereby improving the correction ability of the performance optimization method of the three-electrode gas sensor.

[0097] As shown in the following table, the subscript is the corresponding output table of the actual concentration prediction value based on the calibration concentration value and the preset concentration detection model. Wherein, x represents the calibration concentration value (unit: ppm), and y represents the actual concentration prediction value (unit: ppm).

[0098]

[0099] In an exemplary embodiment, the determination step of the preset concentration detection model comprises:

[0100] The calibration concentration value samples of the three-electrode gas sensor to different mixed gases are obtained to form a concentration data set, wherein the gas composition of the different mixed gases is the same, but the concentration of at least one gas in the different mixed gases is different.

[0101] The concentration data set can be determined based on the data in one forward stroke or reverse stroke, and the concentration data set can also be determined based on the data in multiple forward strokes and / or reverse strokes.

[0102] Based on the BP neural network, the initialized neurons and the concentration data set, the hidden layer node output, the output layer node output and the error of the hidden layer and the output layer of the BP neural network are determined.

[0103] The weights and thresholds of the BP neural network are updated according to the hidden layer node output, the output layer node output and the error until the end condition is reached; wherein the end condition is that the error is less than a preset error or the training number is reached.

[0104] The trained BP neural network is determined as the preset concentration detection model.

[0105] The hidden layer response function corresponding to the hidden layer node can be a tansig function (Hyperbolic Tangent Sigmoid Function, Hyperbolic Tangent Sigmoid Function), the output layer response function corresponding to the output layer node is a purelin function (Linear Activation Function, Linear Activation Function), the number of hidden layer nodes is set to 6, the number of iterations is set to 1000 times, the control error is set to 1E-6, and then the BP neural network is trained based on these data.

[0106] In one exemplary embodiment, the step of acquiring calibration concentration samples of different mixed gases by a three-electrode gas sensor to form a concentration dataset includes:

[0107] Obtain samples of each calibrated concentration value.

[0108] Normalize each calibrated concentration value sample to obtain a concentration dataset.

[0109] Normalization is performed on each calibrated concentration value sample to make the features in the calibrated concentration value sample easier to compare on a uniform scale, thereby accelerating the convergence speed of the gradient descent optimization algorithm and improving the training efficiency of the preset concentration detection model.

[0110] In one embodiment, under DC excitation, the concentration of a preset gas is calibrated to determine the first static characteristic index of the three-electrode gas sensor; under pulse excitation, the concentration of the preset gas is calibrated to determine the second static characteristic index of the three-electrode gas sensor; and the excitation mode of the three-electrode gas sensor is determined based on the first and second static characteristic indices.

[0111] Taking sulfur dioxide as an example, the DC excitation can be a 50V supply voltage and a 1V output voltage DC excitation. Measurements are then performed in five forward and reverse strokes using this DC excitation to obtain the following results: Figure 6 The response characteristic curve is shown. According to the national standard (ISO / IEC 17025) formula for three-electrode gas sensors, the first static characteristic index of the three-electrode gas sensor can be calculated as follows: full-scale output 218.88 nA, zero-scale output 1987.29 nA; reference error γ = 18.2%, sensitivity -22.72 nA / ppm; nonlinearity δL = 9.6%, hysteresis δH = 4.9%, repeatability δR = 10.3%.

[0112] The pulse excitation can be a pulse excitation with a supply voltage of 50V, a duty cycle of 50%, a frequency of 80kHz, and an output voltage of 1V. Measurements of five forward and reverse strokes of this pulse excitation are then performed to obtain... Figure 3 The response characteristic curve is shown. According to the national standard formula for three-electrode gas sensors, the second static characteristic index of the three-electrode gas sensor can be calculated as follows: full-scale output 318.94nA, zero-scale output 5200.39nA; reference error γ=3.8%, maximum sensitivity -13.28nA / μg·m-3; nonlinearity δL=7.9%, hysteresis δH=1.8%, repeatability δR=3.4%.

[0113] The result analysis shows that under different excitation conditions, the output current of the sensor decreases with the increase of the concentration of sulfur dioxide. However, compared with the direct current excitation, the output response value of the three-electrode gas sensor under pulse excitation is higher, the output range is wider, and the single value sensitive characteristic is more obvious. Therefore, the pulse excitation is selected as the excitation mode of the three-electrode gas sensor.

[0114] Correspondingly, based on the performance optimization method of the three-electrode gas sensor, the hydrogen sulfide with different concentrations (10 different concentration points are selected in the concentration range of 0.5-100 ppm) is calibrated under pulse excitation, and the measurement of 5 forward and reverse runs is performed, and the response characteristic curve as shown in Figure 4 can be obtained; the result shows that the response current of the three-electrode gas sensor decreases with the increase of the concentration of hydrogen sulfide, and presents obvious single value variation characteristic, and the output range of the sensor is about 322.4 nA within 0.5-100 ppm. Among them, the second static characteristic index corresponding to hydrogen sulfide: output full scale 310.00 nA, output zero point 4870.75 nA; reference error γ=6.1%, maximum sensitivity -30.02 nA / ppm; non-linearity δL=9.3%, hysteresis δH=5.3%, repeatability δR=2.6%.

[0115] Based on the performance optimization method of the three-electrode gas sensor, the carbon monoxide with different concentrations (10 different concentration points are selected in the concentration range of 2-500 ppm) is calibrated under pulse excitation, and the measurement of 5 forward and reverse runs is performed, and the response characteristic curve as shown in Figure 5 can be obtained; the result shows that the response current of the three-electrode gas sensor decreases with the increase of the concentration of carbon monoxide, and presents obvious single value characteristic, and the output range of the sensor is about 232.9 nA within 2-500 ppm. Among them, the second static characteristic index corresponding to carbon monoxide: output full scale 206.19 nA, output zero point 4483.72 nA; reference error γ=9.7%, maximum sensitivity -14.41 nA / ppm; non-linearity δL=10.9%, hysteresis δH=9.2%, repeatability δR=4.0%.

[0116] Further, as shown in Figure 7 , the electric field intensity of the micron column tip (1.40 mm, 0.68 mm) under direct current excitation is 1.47106V / m, as shown in Figure 8 , and the electric field intensity of the micron column tip under pulse excitation can reach 3.43106V / m, and the electric field intensity under pulse excitation is larger.

[0117] As shown in Figure 9 and Figure 10As shown, the electron density distribution diagram of the three-electrode gas sensor under direct current excitation and pulse excitation, the pulse excitation increases the injection frequency of spatial electron energy, the electron density is nearly 4-6 times higher than that under direct current, the ion migration channel under pulse excitation is wider, and the number density of positive ions in space can reach a peak value of 2.92109 / m-3, and the collection current changes more obviously under pulse excitation. Therefore, the pulse excitation mode is selected as the excitation mode of the three-electrode gas sensor.

[0118] In one exemplary embodiment, as shown in Figure 11 A preparation method of a three-electrode gas sensor is provided, and the structure of the three-electrode gas sensor is as shown in Figure 12 and Figure 13 The method comprises the following steps:

[0119] S702, a collector 702, an extraction electrode 704 and a cathode 706 are provided.

[0120] S704, back hole etching is performed on the side of the cathode away from the extraction electrode to form a plurality of diffusion holes 708.

[0121] S706, micro-column etching is performed on the side of the cathode close to the extraction electrode to form a plurality of first micro-columns 710.

[0122] S708, etching is performed on both sides of the extraction electrode to form a plurality of extraction holes 712 and a plurality of second micro-columns 714.

[0123] S710, micro-column etching and groove etching are performed on the side of the collector close to the extraction electrode to form a plurality of third micro-columns 716 and a plurality of grooves 718; wherein the grooves are arranged opposite to the extraction holes, and each third micro-column is arranged around each groove.

[0124] S712, gold films are sputtered on the surfaces of the cathode, the extraction electrode and the collector, respectively.

[0125] S714, the cathode, the extraction electrode and the collector are all put into an annealing instrument for annealing.

[0126] S716, based on a target electrode spacing, the annealed cathode, extraction electrode and collector are assembled by using a support column 720; wherein the target electrode spacing is determined based on the performance optimization method of the three-electrode gas sensor.

[0127] S718, gold wires 722 are bonded on the surfaces of the cathode, the extraction electrode and the collector, respectively, and encapsulated, so that the gold wires serve as extraction leads to connect an external system.

[0128] The three-electrode gas sensor prepared according to the target inter-electrode distance determined based on the performance optimization method of the three-electrode gas sensor can obtain a three-electrode gas sensor with better performance, thereby improving the detection accuracy of the three-electrode gas sensor.

[0129] In an exemplary embodiment, the method for preparing the three-electrode gas sensor further comprises:

[0130] An aluminum film and a gold film are sequentially plated on the surface of the gold film to form a metal thick film structure.

[0131] The pure gold thick film is relatively high in price, and the aluminum film is doped in the middle of the gold film, so that the preparation cost of the three-electrode gas sensor can be reduced, and the gold films on both sides are corrosion-resistant, thereby prolonging the service life of the three-electrode gas sensor. The gold film, the aluminum film and the gold film form a metal thick film structure, which can improve the conductivity of the surfaces of the electrodes.

[0132] In an exemplary embodiment, the packaging step comprises:

[0133] The tinned iron material is used for packaging.

[0134] The tinned iron is used as an external packaging material, which has a relatively obvious shielding effect on power frequency electric field and electrostatic interference, and can also protect the gold wire bonded on the sensor in terms of physical connection, thereby better protecting the internal structure of the three-electrode gas sensor.

[0135] Taking a three-electrode gas sensor with an inter-electrode distance d=80um as an example, the un-packaged three-electrode gas sensor is placed in a power frequency electric field generator, and the position of the three-electrode gas sensor relative to the generator is kept constant to ensure uniform distribution of the electric field. Under the pulse excitation of a power supply voltage of 50V, a duty ratio of 50%, a frequency of 80kHz and an output voltage of 1V, the power frequency electric field generator generates a power frequency electric field with different intensities of 0-100V / m. Then, the intensity of the power frequency electric field is gradually increased, the three-electrode gas sensor is operated for a period of time at each power frequency electric field intensity, and the output signal of the sensor is recorded. The above process is repeated until all the predetermined power frequency electric field intensity tests are completed. Correspondingly, after the packaged three-electrode gas sensor is executed again, the above steps are executed. By comparing the output quantities of the three-electrode gas sensors with and without packaging under the power frequency electric field interference, the comparison Figure 14 and Figure 15 .

[0136] As Figure 14 and Figure 15The current collected by the three-electrode gas sensor without packaging is slightly higher than that of the three-electrode gas sensor with packaging when there is no power frequency electric field interference (t=0s), which indicates that there is a small amount of other electric field interference in the environment. As the size of the applied external field increases, the size of the output signal of the three-electrode gas sensor without packaging also increases significantly; the size of the output signal of the three-electrode gas sensor with packaging has only a few fluctuations and outliers, indicating that the metal packaging shell has a very significant protective effect on the performance of the three-electrode gas sensor in a power frequency interference environment. The packaging shielding ground can effectively reduce the influence of external power frequency electric field interference on the output of the sensor and improve the anti-interference ability of the three-electrode gas sensor, thereby improving the detection accuracy of the three-electrode gas sensor.

[0137] In an exemplary embodiment, when the mixed gas includes sulfur dioxide, carbon monoxide and hydrogen sulfide, the aperture of the diffusion hole is 1.0-4.0mm;

[0138] The diameter of the first micron column, the second micron column and the third micron column is 10-40um, the height is 50-100um, and the spacing is 20-60um.

[0139] The aperture of the lead-out hole is 2.0-6.0mm.

[0140] The side length of the groove is in the range of 1mm-8mm, and the depth of the groove is in the range of 200um-400um.

[0141] Based on the performance optimization method of the three-electrode gas sensor, different specifications of the first micron column, the second micron column, the third micron column, the lead-out hole and the groove can be set respectively when the target interelectrode distance is determined, so as to determine the one-to-one best size.

[0142] Further, according to the above dimensions, a micro three-electrode gas sensor can be determined, so as to be suitable for various electrical equipment and improve the application range.

[0143] In an exemplary embodiment, the number of diffusion holes is in the range of 6-20; the number of lead-out holes is in the range of 6-20; and the number of grooves is in the range of 6-20.

[0144] The number of diffusion holes, the number of lead-out holes and the number of grooves can be determined based on the measurement accuracy of the three-electrode gas sensor and the simplicity of the preparation process.

[0145] As shown in the following table, the three-electrode gas sensor (SO2 sensor, H2S sensor and CO sensor) determined by the preparation method of the three-electrode gas sensor has the advantage of miniaturization in volume, is light and easy to carry, and is easy to promote.

[0146]

[0147] In one exemplary embodiment, a three-electrode gas sensor array is provided, comprising: a first gas sensor, a second gas sensor and a third gas sensor, which are all fabricated based on the above-mentioned preparation method of three-electrode gas sensor.

[0148] Wherein, the collecting electrode of the first gas sensor, the collecting electrode of the second gas sensor and the collecting electrode of the third gas sensor are on the same plane.

[0149] Wherein, the preset gas corresponding to the first gas sensor is sulfur dioxide; the preset gas corresponding to the second gas sensor is carbon monoxide; and the preset gas corresponding to the third gas sensor is hydrogen sulfide.

[0150] As shown in Figure 16 , Figure 17 and Figure 18 , when detecting the same gas, the output current of the three sensors (the first gas sensor, the second gas sensor and the third gas sensor) in the three-electrode gas sensor array decreases with the increase of the concentration of different kinds of gas, and there is a significant difference between the output current values of different electrode spacings, and the output current of the small spacing sensor is larger. This shows that under the same conditions, the focusing electric field of small spacing enhances the electron density of field emission, thereby verifying the principle of sensor array detecting mixed gas, and showing that the three-electrode gas sensor array can detect the concentration of mixed gas without separating the mixed gas.

[0151] It should be understood that, although each step in the flowchart involved in each of the above-mentioned embodiments is shown in sequence according to the direction of the arrow, these steps are not necessarily executed in sequence according to the direction of the arrow. Unless otherwise stated herein, there is no strict order limitation for the execution of these steps, and these steps can be executed in other orders. Moreover, at least part of the steps in the flowchart involved in each of the above-mentioned embodiments can include multiple steps or stages, which are not necessarily executed at the same time, but can be executed at different times, and the execution order of these steps or stages is not necessarily sequential, but can be executed in rotation or alternation with at least part of other steps or steps or stages in other steps.

[0152] Those skilled in the art can understand that all or part of the processes in the above-mentioned embodiment methods can be completed by instructing the relevant hardware through a computer program. The computer program can be stored in a non-volatile computer readable storage medium, and when executed, can include the processes of the above-mentioned embodiment methods. Any reference to memory, database or other medium used in the embodiments provided in the present application can include at least one of non-volatile memory and volatile memory. The non-volatile memory can include read-only memory (ROM), magnetic tape, floppy disk, flash memory, optical storage, high-density embedded non-volatile memory, resistive random access memory (ReRAM), magnetoresistive random access memory (MRAM), ferroelectric random access memory (FRAM), phase change memory (PCM), graphene memory, etc. The volatile memory can include random access memory (RAM) or external cache memory, etc. As an illustration but not limitation, the RAM can be in various forms, such as static random access memory (SRAM) or dynamic random access memory (DRAM), etc. The database involved in the embodiments provided in the present application can include at least one of a relational database and a non-relational database. The non-relational database can include a distributed database based on a block chain, etc., without being limited thereto. The processor involved in the embodiments provided in the present application can be a general-purpose processor, a central processing unit, a graphics processing unit, a digital signal processor, a programmable logic device, a data processing logic device based on quantum computing, an artificial intelligence (AI) processor, etc., without being limited thereto.

[0153] The technical features of the above embodiments can be combined in any manner. To make the description concise, all possible combinations of the technical features in the above embodiments are not described, but as long as the combinations of the technical features do not exist contradictions, they should be considered as the scope of the present application.

[0154] The above-described embodiments are merely illustrative of several embodiments of the present application, and the description is relatively specific and detailed, but should not be understood as a limitation on the scope of the patent. It should be noted that for those skilled in the art, without departing from the concept of the present application, a number of modifications and improvements can be made, which are all within the scope of the present application. Therefore, the scope of protection of the present application should be subject to the appended claims.

Claims

1. A method of performance optimization of a three-electrode gas sensor, characterized in that, The three-electrode gas sensor comprises a cathode, an extraction electrode and a collection electrode which are sequentially and spacedly stacked; and the method comprises: The following steps are cyclically executed until a sensitivity maximum value is determined, and the interelectrode distance corresponding to the sensitivity maximum value is taken as a target interelectrode distance of the three-electrode gas sensor: The gas in the three-electrode gas sensor is exhausted to a vacuum state based on a vacuum pump; A mixed gas with a preset concentration is introduced into the three-electrode gas sensor until the internal pressure of the three-electrode gas sensor reaches one standard atmosphere, and a first current value output by the three-electrode gas sensor is recorded; The concentration of the preset gas in the three-electrode gas sensor is adjusted, and a corresponding second current value is recorded; wherein the preset gas is any one of the mixed gas; The sensitivity corresponding to the interelectrode distance is determined according to the first current value, the concentration of the preset gas corresponding to the first current value, the second current value and the concentration of the preset gas corresponding to the second current value; The interelectrode distance is adjusted.

2. The method of claim 1, wherein, Further comprising: A calibration concentration value of the preset gas for the three-electrode gas sensor is obtained; The calibration concentration value is input into a preset concentration detection model to obtain an actual concentration prediction value of each gas concentration corresponding to the calibration concentration value; A gas concentration influence coefficient is determined according to the actual concentration prediction value and the above calibration concentration value; Each calibration concentration value of the three-electrode gas sensor is corrected according to the gas concentration influence coefficient.

3. The method of claim 2, wherein, The determination step of the preset concentration detection model comprises: Different mixed gas calibration concentration value samples of the three-electrode gas sensor are obtained to form a concentration data set; wherein the gas composition of the different mixed gases is the same, but the concentration of at least one gas in the different mixed gases is inconsistent; Based on a BP neural network, initialized neurons and the concentration data set, the hidden layer node output, the output layer node output and the error of the hidden layer and the output layer of the BP neural network are determined; The weights and thresholds of the BP neural network are updated according to the hidden layer node output, the output layer node output and the error until the end condition is reached; wherein the end condition is that the error is less than a preset error or the training number is reached; The trained BP neural network is determined as the preset concentration detection model.

4. The method of claim 3, wherein, The different mixed gas calibration concentration value samples of the three-electrode gas sensor are obtained to form a concentration data set, comprising: Each calibration concentration value sample is obtained; Each calibration concentration value sample is normalized to obtain the concentration data set.

5. A method for producing a three-electrode gas sensor, characterized by Comprising: A collection electrode, an extraction electrode and a cathode are provided; Back hole etching is performed on the side of the cathode away from the extraction electrode to form a plurality of diffusion holes; Microcolumn etching is performed on the side of the cathode close to the extraction electrode to form a plurality of first micropillars; Both sides of the extraction electrode are etched to form a plurality of extraction holes and a plurality of second micropillars; Micro-column etching and groove etching are performed on one side of the collector close to the extraction electrode to form a plurality of third micro-columns and a plurality of grooves; wherein the grooves are arranged opposite to each extraction hole, and each third micro-column is arranged around each groove; A gold film is sputtered on the surface of the cathode, the extraction electrode and the collector respectively; The cathode, the extraction electrode and the collector are all put into an annealing instrument for annealing; Based on a target electrode spacing, the annealed cathode, the extraction electrode and the collector are assembled by support columns; wherein the target electrode spacing is determined based on the method of any one of claims 1-3; Gold wires are bonded on the surface of the cathode, the extraction electrode and the collector respectively and packaged, so that the gold wires are connected to an external system as extraction leads.

6. The method of claim 5, wherein, Further comprising: An aluminum film and a gold film are sequentially plated on the surface of the gold film to form a metal thick film structure.

7. The method of claim 5, wherein, The packaging step comprises: Tinned iron material is used for packaging.

8. The method of claim 5, wherein, When the mixed gas comprises sulfur dioxide, carbon monoxide and hydrogen sulfide, the aperture of the diffusion hole is 1.0-4.0 mm; The diameter of the first micro-column, the second micro-column and the third micro-column is 10-40 μm, the height is 50-100 μm, and the spacing is 20-60 μm; The aperture of the extraction hole is 2.0-6.0 mm; The side length of the groove is in the range of 1 mm-8 mm, and the depth of the groove is in the range of 200 um-400 um.

9. The method of claim 5, wherein, The number of diffusion holes is in the range of 6-20; the number of extraction holes is in the range of 6-20; and the number of grooves is in the range of 6-20.

10. A three-electrode gas sensor array, characterized by Comprising: A first gas sensor, a second gas sensor and a third gas sensor are all made based on the method of any one of claims 5-9; The collector of the first gas sensor, the collector of the second gas sensor and the collector of the third gas sensor are on the same plane; Wherein, the preset gas corresponding to the first gas sensor is sulfur dioxide; the preset gas corresponding to the second gas sensor is carbon monoxide; and the preset gas corresponding to the third gas sensor is hydrogen sulfide.

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