A chlorobenzene sensor and preparation method thereof

Abstract

The invention discloses a chlorobenzene sensor and a preparation method thereof, wherein the preparation method comprises: preparing gas-sensitive material powder with zinc salt, nano-alumina, palladium nitrate, carboxymethyl cellulose and deionized water as raw materials, grinding, sand milling, controlling the slurry discharge particle size D90=300-400nm after sand milling, and obtaining a gas-sensitive material slurry with a solid content of 5-15%; placing the gas-sensitive material slurry in the center of a MEMS microheater substrate wafer for spin coating, and drying; heat treating the MEMS microheater substrate wafer loaded with gas-sensitive material in an air atmosphere of 400-500°C, cutting after cooling, and then welding and packaging. The sensor prepared by the present invention has good sensing performance for chlorobenzene, low detection limit, short response time and recovery time.

Description

Technical Field

[0001] The invention relates to the technical field of micro-nano sensor applications, and in particular to a chlorobenzene sensor and a preparation method thereof. Background Art

[0002] In 2001, 127 countries and regions in the world signed the Stockholm Convention on Persistent Organic Pollutants (POPs) in Sweden. The convention announced the first 12 types of persistent organic pollutants that were banned or strictly restricted worldwide, including hexachlorobenzene. Chlorobenzene compounds (CBs for short) are mostly persistent organic pollutants. They are ubiquitous in the atmosphere, water bodies, sediments and soil environments, and have very stable physical and chemical properties. They are artificially synthesized organic compounds that are extremely difficult to dissolve in water and have very high potential toxicity. Chemical materials, artificial boards and composite boards use a large amount of chlorobenzene compounds as additives for solvents, adhesives and dyes. Residual chlorobenzene in indoor materials will gradually be released through the air, causing varying degrees of harm to the human body, and the harm period is long.

[0003] Gas chromatography, gas chromatography-mass spectrometry, and high performance liquid chromatography are the main detection methods for chlorobenzene compounds. Gas chromatography is the most commonly used method because of its good detection effect and fast analysis speed. Gas chromatography-mass spectrometry combines the advantages of chromatography and mass spectrometry. The advantages of high performance liquid chromatography are high resolution, fast analysis speed, good repeatability, and high precision of quantitative analysis. However, the above detection methods are only suitable for testing in laboratories due to the large size and high price of the equipment. Therefore, the development of methods for quickly, accurately, and conveniently detecting chlorobenzene pollution has attracted widespread attention. The sensors made by semiconductor metal oxide gas-sensitive materials combined with micro-electromechanical systems (MEMS) have the advantages of high sensitivity, fast response, small size, and simple production. The development of new gas-sensitive materials and new gas-sensitive sensors can make MEMS gas sensors more miniaturized, multifunctional, and high-performance, and has become one of the main development directions of semiconductor gas-sensitive sensors at home and abroad.

[0004] There are not many patent reports on MEMS gas sensors for chlorobenzene detection. The Chinese patent application document with publication number CN101281159A discloses a nano zinc oxide multifunctional gas sensor device and its manufacturing method. The gas sensor device adopts a side-heated device structure, with an alumina ceramic tube as a carrier, a forked gold electrode on the outer surface, platinum wire lead electrodes at both ends, a heating wire in the ceramic tube, and a gas-sensitive material coated on the outside of the ceramic tube. The gas-sensitive material is a nano zinc oxide powder with a flaky porous structure. The sensor is used for 100-250ppm chlorobenzene detection in the temperature range of 150℃<T<250℃. The response and recovery time of chlorobenzene are 103s and 22s respectively. The sensor is not suitable for low-concentration chlorobenzene detection and has a long response / recovery time. The Chinese patent application document with publication number CN103101973A discloses a vanadium and palladium co-doped nano-titanium dioxide gas-sensitive material and its preparation method and application. The gas-sensitive material is based on nano-titanium dioxide, doped with vanadium and palladium, and coated on a ceramic tube. After sintering, the tube core is made, and the gas-sensitive sensor device is made by welding, packaging, and electrical aging according to the conventional process of the indirect heating device. The sensor detects 100ppm chlorobenzene at an operating temperature of 175°C, and the response and recovery times are 12s and 28s respectively. The sensor still has a high detection concentration for chlorobenzene, and the response / recovery time is long. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a MEMS gas sensor for chlorobenzene with fast response and low detection limit and a preparation method thereof.

[0006] The present invention solves the above technical problems through the following technical means:

[0007] A method for preparing a chlorobenzene sensor comprises the following steps:

[0008] S1. Prepare gas-sensitive material powder using zinc salt, nano-alumina, palladium nitrate, carboxymethyl cellulose and deionized water as raw materials;

[0009] S2, grinding the gas-sensitive material powder prepared in S1, and then sand-milling, controlling the particle size D90 of the slurry after sand-milling to be 300-400 nm, to obtain a gas-sensitive material slurry, wherein the solid content of the gas-sensitive material slurry is 5-15%;

[0010] S3, placing the gas-sensitive material slurry in S2 at the center of the MEMS micro-heater substrate wafer, and spin coating at a rotation speed of 1000-2000 rpm for 30-90 seconds, and drying the MEMS micro-heater substrate wafer after the spin coating is completed;

[0011] S4, heat-treating the MEMS micro-heater substrate wafer loaded with the gas-sensitive material in S3 in an air atmosphere of 400-500° C., and cutting it after cooling to obtain a MEMS chlorobenzene sensor chip;

[0012] S5. Welding and packaging the MEMS chlorobenzene sensor chip prepared in S4 to obtain the chlorobenzene sensor.

[0013] Beneficial effects: In the present application, specific raw materials are used to prepare gas-sensitive material powder, the prepared gas-sensitive material powder is ground and then sand-milled, and the particle size and solid content of the slurry after sand-milling are controlled. It is then spin-coated on a MEMS microheater, and the annealing temperature is controlled, so that the specific gas-sensitive material is combined with a specific process, and the resulting sensor has good sensing performance for chlorobenzene, a low detection limit, and short response time and recovery time.

[0014] Preferably, in S1, the zinc salt is one of zinc sulfate, zinc chloride and zinc nitrate.

[0015] Preferably, in S1, the D90 of the nano-alumina is 80-120 nm.

[0016] Preferably, in S1, D90 of the nano-alumina is 100 nm.

[0017] Preferably, in S1, the mass ratio of the zinc salt, nano-alumina, palladium nitrate, carboxymethyl cellulose and deionized water is 30-40: 5-10: 0.5-1.5: 2: 46.5-62.5.

[0018] Preferably, in S1, zinc salt, nano-alumina, palladium nitrate, carboxymethyl cellulose and deionized water are stirred at room temperature in a mass ratio to obtain a suspension; the suspension temperature is then increased and stirred continuously until it is completely dried, and then calcined to obtain a gas-sensitive material powder.

[0019] Preferably, the stirring speed at room temperature is 700-900 rpm, and the time is 1-3 hours; then the suspension temperature is increased to 85-95°C, and the stirring is continued at a speed of 450-550 rpm; the calcination temperature is 450-550°C, and the time is 1.5-2.5 hours.

[0020] Preferably, the stirring speed at room temperature is 800 rpm and the time is 1 hour; then the suspension temperature is raised to 90° C. and the stirring is continued at a speed of 500 rpm; the calcination temperature is 500° C. and the time is 2 hours.

[0021] Preferably, in S2, grinding is performed to a particle size of 150-250 meshes; during the sand milling process, ethanol is used as a solvent, the sand mill speed is 800-1200 rpm, and the sand milling temperature is 30-35°C.

[0022] Preferably, in S2, the powder is ground to a particle size of 200 mesh.

[0023] Preferably, in S2, during the sand milling process, ethanol is used as the solvent, the sand mill speed is 1000 rpm, and the sand milling temperature is 30°C.

[0024] Preferably, in S3, 8-12 g of gas-sensitive material slurry is dripped onto the center of a 4-inch MEMS micro-heater substrate wafer; the drying temperature is 75-85° C., and the drying time is 0.5-1.5 h.

[0025] Preferably, in S3, 10 g of gas-sensitive material slurry is dropped on the center of a 4-inch MEMS micro-heater substrate wafer; the drying temperature is 80° C. and the drying time is 1 hour.

[0026] Preferably, in S4, the heat treatment time is 2.5-3.5 hours.

[0027] Preferably, in S4, the heat treatment time is 3 hours.

[0028] The present invention also provides a chlorobenzene sensor, which is prepared by adopting the preparation method of the chlorobenzene sensor.

[0029] The present invention first prepares gas-sensitive material powder by a co-mixing method, then prepares gas-sensitive material slurry by a sand milling method, loads the gas-sensitive material slurry onto a MEMS micro-heater substrate by a spin coating method, and then obtains a chlorobenzene MEMS gas sensor after annealing, cutting, welding and packaging of a MEMS gas device. The chlorobenzene MEMS gas sensor prepared based on the above steps has more excellent performance and high repeatability, and the preparation method of the gas-sensitive material is simple, and the process of combining with a semiconductor MEMS micro-heating plate is simple and easy to operate, and has the potential for large-scale mass production.

[0030] The advantages of the present invention are:

[0031] 1. The MEMS micro-heating plate process is used instead of the traditional ceramic tube heating process, and the sensor performance is more excellent;

[0032] 2. The particle size of the gas-sensitive material of the present invention is small and uniform, and the preparation method of the gas-sensitive material is simple;

[0033] 3. The gas-sensitive material bonding process is simple, the gas-sensitive material coating is thin and uniform, and the gas sensor has good performance and high repeatability;

[0034] 4. The sensor preparation process is simple and has the potential for large-scale mass production;

[0035] 5. The sensor has a low detection limit of 50ppm for chlorobenzene, and the response time and recovery time are within 9s and 22s respectively. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a schematic diagram of the packaged chlorobenzene sensor;

[0037] Figure 2 This is a physical picture of the alumina ceramic tube substrate in Comparative Example 3;

[0038] Figure 3 This is a physical picture of the alumina ceramic tube heater in Comparative Example 3;

[0039] Figure 4 This is the response recovery curve of the chlorobenzene sensor prepared in Example 1 of the present invention to 50 ppm chlorobenzene. DETAILED DESCRIPTION

[0040] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described in combination with the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0041] Unless otherwise specified, the test materials and reagents used in the following examples can be obtained from commercial sources.

[0042] If no specific techniques or conditions are specified in the examples, they can be carried out according to the techniques or conditions described in the literature in the art or according to the product instructions.

[0043] Example 1

[0044] A method for preparing a chlorobenzene sensor comprises the following steps:

[0045] (1) Preparation of gas-sensitive material powder

[0046] Zinc sulfate, nano-alumina (D90=100nm), palladium nitrate, carboxymethyl cellulose and deionized water were stirred at 800rpm at room temperature for 1h in a mass ratio of 30:5:0.5:2:62.5, and then the suspension was obtained. The temperature of the suspension was raised to 90°C and stirred at 500rpm until it was completely dried, and then calcined at 500°C for 2h to obtain a gas-sensitive material powder.

[0047] (2) Preparation of gas-sensitive material slurry

[0048] The gas-sensitive material powder prepared above was ground to 200 mesh, and sand-milled with ethanol as solvent, with a sand mill speed of 1000 rpm and a sand mill temperature of 30° C. The particle size of the slurry after sand milling was controlled to be D90=300 nm, to obtain a gas-sensitive material slurry with a solid content of 5%.

[0049] (3) Spin coating of gas-sensitive materials

[0050] 10g of the above gas-sensitive material slurry was dropped on the center of a 4-inch MEMS microheater substrate wafer and spin-coated at 1000 rpm for 30 seconds. After the spin coating, the MEMS microheater substrate wafer was dried at 80°C for 1 hour.

[0051] (4) Gas sensor post-processing

[0052] The MEMS microheater substrate wafer loaded with the gas-sensitive material was heat-treated at 400° C. in air atmosphere for 3 hours, and then cut after cooling to obtain a MEMS chlorobenzene sensor chip.

[0053] (5) Gold wire ball welding, ceramic packaging

[0054] The prepared MEMS chlorobenzene sensor chip is subjected to gold wire ball welding and ceramic packaging to obtain the chlorobenzene sensor.

[0055] Example 2

[0056] A method for preparing a chlorobenzene sensor comprises the following steps:

[0057] (1) Preparation of gas-sensitive material powder

[0058] Zinc chloride, nano-alumina (D90=100nm), palladium nitrate, carboxymethyl cellulose and deionized water were stirred at 800rpm at room temperature for 1h in a mass ratio of 35:7.5:1:2:54.5 to obtain a suspension. The temperature of the obtained suspension was then raised to 90°C and stirred at 500rpm until completely dried. The suspension was then calcined at 500°C for 2h to obtain a gas-sensitive material powder.

[0059] (2) Preparation of gas-sensitive material slurry

[0060] The gas-sensitive material powder prepared above was ground to 200 mesh, and sand-milled with ethanol as solvent, with a sand mill speed of 1000 rpm and a sand mill temperature of 30° C. The particle size of the slurry after sand milling was controlled to be D90=350 nm, to obtain a gas-sensitive material slurry with a solid content of 10%.

[0061] (3) Spin coating of gas-sensitive materials

[0062] 10g of the above gas-sensitive material slurry was dropped on the center of a 4-inch MEMS microheater substrate wafer and spin-coated at 1500 rpm for 60 seconds. After the spin coating, the MEMS microheater substrate wafer was dried at 80°C for 1 hour.

[0063] (4) Gas sensor post-processing

[0064] The MEMS microheater substrate wafer loaded with the gas-sensitive material was heat treated at 450° C. in air atmosphere for 3 hours, and then cut after cooling to obtain a MEMS chlorobenzene sensor chip.

[0065] (5) Gold wire ball welding, ceramic packaging

[0066] The prepared MEMS chlorobenzene sensor chip is subjected to gold wire ball welding and ceramic packaging to obtain the chlorobenzene sensor.

[0067] Example 3

[0068] A method for preparing a chlorobenzene sensor comprises the following steps:

[0069] (1) Preparation of gas-sensitive material powder

[0070] Zinc nitrate, nano-alumina (D90=100nm), palladium nitrate, carboxymethyl cellulose and deionized water are stirred at 800rpm at room temperature for 1h in a mass ratio of 40:10:1.5:2:46.5 to obtain a suspension. The temperature of the obtained suspension is then raised to 90°C and stirred at 500rpm until completely dried. The suspension is then calcined at 500°C for 2h to obtain a gas-sensitive material powder.

[0071] (2) Preparation of gas-sensitive material slurry

[0072] The gas-sensitive material powder prepared above was ground to 200 mesh, and sand-milled with ethanol as solvent, with a sand mill speed of 1000 rpm and a sand mill temperature of 30° C. The particle size of the slurry after sand milling was controlled to be D90=400 nm, to obtain a gas-sensitive material slurry with a solid content of 15%.

[0073] (3) Spin coating of gas-sensitive materials

[0074] 10g of the above gas-sensitive material slurry was dropped on the center of a 4-inch MEMS microheater substrate wafer and spin-coated at 2000rpm for 90 seconds. After the spin coating, the MEMS microheater substrate wafer was dried at 80°C for 1 hour.

[0075] (4) Gas sensor post-processing

[0076] The MEMS microheater substrate wafer loaded with the gas-sensitive material was heat-treated at 500° C. in air atmosphere for 3 hours, and then cut after cooling to obtain a MEMS chlorobenzene sensor chip.

[0077] (5) Gold wire ball welding, ceramic packaging

[0078] The prepared MEMS chlorobenzene sensor chip is subjected to gold wire ball welding and ceramic packaging to obtain the chlorobenzene sensor.

[0079] Example 4

[0080] A method for preparing a chlorobenzene sensor comprises the following steps:

[0081] (1) Preparation of gas-sensitive material powder

[0082] Zinc nitrate, nano-alumina (D90=80nm), palladium nitrate, carboxymethyl cellulose and deionized water were stirred at 900rpm for 2h at room temperature in a mass ratio of 40:10:1.5:2:46.5 to obtain a suspension. The temperature of the obtained suspension was then raised to 85°C and stirred at 450rpm until completely dried. The suspension was then calcined at 450°C for 2.5h to obtain a gas-sensitive material powder.

[0083] (2) Preparation of gas-sensitive material slurry

[0084] The gas-sensitive material powder prepared above was ground into 150 mesh, and sand-milled with ethanol as solvent, with a sand-mill speed of 1200 rpm and a sand-milling temperature of 30° C. The particle size of the slurry after sand-milling was controlled to be D90=400 nm, to obtain a gas-sensitive material slurry with a solid content of 15%.

[0085] (3) Spin coating of gas-sensitive materials

[0086] 8g of the above gas-sensitive material slurry was dropped on the center of a 4-inch MEMS microheater substrate wafer and spin-coated at 2000 rpm for 90 seconds. After the spin coating, the MEMS microheater substrate wafer was dried at 85°C for 0.5h.

[0087] (4) Gas sensor post-processing

[0088] The MEMS micro-heater substrate wafer loaded with the gas-sensitive material was heat-treated at 500° C. in air atmosphere for 2.5 hours, and then cut after cooling to obtain a MEMS chlorobenzene sensor chip.

[0089] (5) Gold wire ball welding, ceramic packaging

[0090] The prepared MEMS chlorobenzene sensor chip is subjected to gold wire ball welding and ceramic packaging to obtain the chlorobenzene sensor.

[0091] Example 5

[0092] A method for preparing a chlorobenzene sensor comprises the following steps:

[0093] (1) Preparation of gas-sensitive material powder

[0094] Zinc nitrate, nano-alumina (D90=120nm), palladium nitrate, carboxymethyl cellulose and deionized water were stirred at 700rpm at room temperature for 3h in a mass ratio of 40:10:1.5:2:46.5 to obtain a suspension. The temperature of the obtained suspension was then raised to 95°C and stirred at 550rpm until completely dried. The suspension was then calcined at 550°C for 1.5h to obtain a gas-sensitive material powder.

[0095] (2) Preparation of gas-sensitive material slurry

[0096] The gas-sensitive material powder prepared above was ground to 250 mesh, and sand-milled with ethanol as solvent, with a sand mill speed of 800 rpm and a sand mill temperature of 35° C. The particle size of the slurry after sand milling was controlled to be D90=400 nm, to obtain a gas-sensitive material slurry with a solid content of 15%.

[0097] (3) Spin coating of gas-sensitive materials

[0098] 12g of the above gas-sensitive material slurry was dropped on the center of a 4-inch MEMS microheater substrate wafer and spin-coated at 2000 rpm for 90 seconds. After the spin coating, the MEMS microheater substrate wafer was dried at 75°C for 1.5 hours.

[0099] (4) Gas sensor post-processing

[0100] The MEMS micro-heater substrate wafer loaded with the gas-sensitive material was heat-treated at 500° C. in air atmosphere for 3.5 hours, and then cut after cooling to obtain a MEMS chlorobenzene sensor chip.

[0101] (5) Gold wire ball welding, ceramic packaging

[0102] The prepared MEMS chlorobenzene sensor chip is subjected to gold wire ball welding and ceramic packaging to obtain the chlorobenzene sensor.

[0103] Comparative Example 1

[0104] (1) Preparation of gas-sensitive material powder

[0105] Zinc sulfate, nano-alumina (D90=100nm), palladium nitrate, carboxymethyl cellulose and deionized water were stirred at 800rpm at room temperature in a mass ratio of 30:5:0.5:2:62.5 for 1h, and then the suspension temperature was raised to 90°C and stirred at 500rpm until completely dried, and then calcined at 500°C for 2h to obtain gas-sensitive material powder.

[0106] (2) Preparation of gas-sensitive material slurry

[0107] The gas-sensitive material powder prepared above was ground to 200 mesh, and stirred at high speed with ethanol as solvent, with a stirring speed of 1000 rpm and a stirring temperature of 30° C. The particle size of the slurry after stirring was controlled to be D90=300 nm, to obtain a gas-sensitive material slurry with a solid content of 5%.

[0108] (3) Spin coating of gas-sensitive materials

[0109] 10g of the above gas-sensitive material slurry was dropped on the center of a 4-inch MEMS microheater substrate wafer and spin-coated at 1000 rpm for 30 seconds. After the spin coating, the MEMS microheater substrate wafer was dried at 80°C for 1 hour.

[0110] (4) Gas sensor post-processing

[0111] The MEMS microheater substrate wafer loaded with the gas-sensitive material was heat-treated at 400° C. in air atmosphere for 3 hours, and then cut after cooling to obtain a MEMS chlorobenzene sensor chip.

[0112] (5) Gold wire ball welding, ceramic packaging

[0113] The prepared MEMS chlorobenzene sensor chip is subjected to gold wire ball welding and ceramic packaging to obtain a MEMS chlorobenzene sensor.

[0114] Comparative Example 2

[0115] (1) Preparation of gas-sensitive material powder

[0116] Zinc sulfate, nano-alumina (D90=100nm), palladium nitrate, carboxymethyl cellulose and deionized water were stirred at 800rpm at room temperature in a mass ratio of 30:5:0.5:2:62.5 for 1h, and then the suspension temperature was raised to 90°C and stirred at 500rpm until completely dried, and then calcined at 500°C for 2h to obtain gas-sensitive material powder.

[0117] (2) Preparation of gas-sensitive material slurry

[0118] The gas-sensitive material powder prepared above was ground to 200 mesh, and sand-milled with ethanol as solvent, with a sand mill speed of 1000 rpm and a sand mill temperature of 30° C. The particle size of the slurry after sand milling was controlled to be D90=300 nm, to obtain a gas-sensitive material slurry with a solid content of 5%.

[0119] (3) Gas-sensitive material load

[0120] The gas-sensitive material slurry is dropped onto a single MEMS microheater substrate to cover the single MEMS microheater with the slurry, and then dried at 80° C. for 1 h.

[0121] (4) Gas sensor post-processing

[0122] The MEMS substrate loaded with the gas-sensitive material is heat-treated at 400° C. in air atmosphere for 3 hours, and then cooled to obtain a MEMS chlorobenzene sensor chip.

[0123] (5) Gold wire ball welding, ceramic packaging

[0124] The prepared MEMS chlorobenzene sensor chip is subjected to gold wire ball welding and ceramic packaging to obtain a MEMS chlorobenzene sensor.

[0125] Comparative Example 3

[0126] (1) Preparation of gas-sensitive material powder

[0127] Zinc sulfate, nano-alumina (D90=100nm), palladium nitrate, carboxymethyl cellulose and deionized water were stirred at 800rpm at room temperature in a mass ratio of 30:5:0.5:2:62.5 for 1h, and then the suspension temperature was raised to 90°C and stirred at 500rpm until completely dried, and then calcined at 500°C for 2h to obtain gas-sensitive material powder.

[0128] (2) Preparation of gas-sensitive material slurry

[0129] The gas-sensitive material powder prepared above was ground to 200 mesh, and sand-milled with ethanol as solvent, with a sand mill speed of 1000 rpm and a sand mill temperature of 30° C. The particle size of the slurry after sand milling was controlled to be D90=300 nm, to obtain a gas-sensitive material slurry with a solid content of 5%.

[0130] (3) Gas-sensitive material load

[0131] Immerse the alumina ceramic tube with interdigital electrodes and heating wires in the above-mentioned gas-sensitive material slurry for 10 seconds, then take it out and spin dry it to make the gas-sensitive material slurry evenly coated on the alumina ceramic tube. After completion, dry the ceramic tube at 80°C for 1 hour.

[0132] (4) Gas sensor post-processing

[0133] The ceramic tube loaded with the gas-sensitive material is heat-treated in an air atmosphere at 400° C. for 3 h, and then cooled to obtain a ceramic tube-type chlorobenzene sensor.

[0134] Figure 1 is a schematic diagram of the packaged chlorobenzene sensor; Figure 1 It can be seen that the chlorobenzene sensor needs to be encapsulated in a ceramic shell for testing and use; Figure 2 This is a physical picture of the alumina ceramic tube substrate in Comparative Example 3; Figure 3 This is a physical picture of the alumina ceramic tube heater in Comparative Example 3; Figure 2 and Figure 3After the alumina ceramic tube substrate and the alumina ceramic tube heater are assembled, a complete ceramic tube sensor substrate is obtained, and the heater provides the ceramic tube substrate with the necessary temperature for sensor detection.

[0135] Device gas sensing performance test:

[0136] The gas sensors in the embodiments and comparative examples were tested for their gas-sensitive performance. The gas-sensitive performance of the device was tested using a source-meter multi-channel gas-sensitive test platform (SMP-4) developed by the Institute of Solid State Physics, Hefei Institutes of Physical Science, Chinese Academy of Sciences. The multimeter / DC power supply (Agilent U3606A and U8002A) provides a voltage source and collects voltage signals. Gases or steam of different concentrations are injected into the test cavity from the injection port. Two 300rpm rotating fans are symmetrically distributed near the gas injection port. The uniform mixing of the gas in the cavity can be completed within 0.1 seconds. Gas injection will cause the resistance of the device to change, which is reflected as a voltage change in the circuit. LabVIEW software is used to control and collect signals at a rate of 20 times / second. The tests were all carried out under environmental conditions of relative humidity of 60% RH and room temperature of 25°C. The results of the tests are shown in Table 1.

[0137] Table 1 Gas sensing performance test results of the sensor devices in the embodiments and comparative examples

[0138]

[0139] According to Table 1 and Figure 4 The results show that the chlorobenzene sensor obtained by sand grinding to obtain the gas-sensitive material slurry and then loading it onto the MEMS microheater substrate by spin coating has better performance, and the response time and recovery time to 50ppm chlorobenzene gas are within 9s and 22s respectively. From the comparative examples, it can be seen that the response time and recovery time of the sample using the high-speed dispersion method instead of the sand grinding method to 50ppm chlorobenzene gas are about 25s and 50s respectively; the response time and recovery time of the sample using the drop coating method instead of the spin coating method to 50ppm chlorobenzene gas are about 26s and 56s respectively; the response time and recovery time of the sample using the alumina ceramic tube as the heating substrate instead of the MEMS micro substrate as the heater are about 33s and 69s respectively.

[0140] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for preparing a chlorobenzene sensor, characterized in that: The following steps are involved: S1. Prepare gas-sensitive material powder using zinc salt, nano-alumina, palladium nitrate, carboxymethyl cellulose and deionized water as raw materials; the mass ratio of zinc salt, nano-alumina, palladium nitrate, carboxymethyl cellulose and deionized water is 30-40: 5-10: 0.5-1.5: 2: 46.5-62.5; S2, grinding the gas-sensitive material powder prepared in S1, and then sand-milling, controlling the particle size D90 of the slurry after sand-milling to be 300-400 nm, to obtain a gas-sensitive material slurry, wherein the solid content of the gas-sensitive material slurry is 5-15%; S3, placing the gas-sensitive material slurry in S2 at the center of the MEMS micro-heater substrate wafer, and spin coating at a rotation speed of 1000-2000 rpm for 30-90 seconds, and drying the MEMS micro-heater substrate wafer after the spin coating is completed; S4, heat-treating the MEMS micro-heater substrate wafer loaded with the gas-sensitive material in S3 in an air atmosphere of 400-500° C., and cutting it after cooling to obtain a MEMS chlorobenzene sensor chip; S5. Welding and packaging the MEMS chlorobenzene sensor chip prepared in S4 to obtain the chlorobenzene sensor.

2. The method for preparing the chlorobenzene sensor according to claim 1, characterized in that: In S1, the zinc salt is one of zinc sulfate, zinc chloride and zinc nitrate.

3. The method for preparing the chlorobenzene sensor according to claim 1, characterized in that: In S1, the D90 of the nano-alumina is 80-120 nm.

4. The method for preparing a chlorobenzene sensor according to any one of claims 1 to 3, characterized in that: In S1, zinc salt, nano-alumina, palladium nitrate, carboxymethyl cellulose and deionized water are stirred at room temperature according to mass proportion to obtain a suspension; the suspension temperature is then increased and stirred continuously until it is completely dried, and then calcined to obtain a gas-sensitive material powder.

5. The method for preparing the chlorobenzene sensor according to claim 4, characterized in that: The stirring speed at room temperature is 700-900 rpm, and the time is 1-3 hours; then the suspension temperature is increased to 85-95°C, and the stirring is continued at a speed of 450-550 rpm; the calcination temperature is 450-550°C, and the time is 1.5-2.5 hours.

6. The method for preparing the chlorobenzene sensor according to claim 1, characterized in that: In S2, grinding is performed to a particle size of 150-250 meshes; during the sand milling process, ethanol is used as a solvent, the sand mill speed is 800-1200 rpm, and the sand milling temperature is 30-35°C.

7. The method for preparing the chlorobenzene sensor according to claim 1, characterized in that: In S3, 8-12 g of gas-sensitive material slurry is dropped on the center of a 4-inch MEMS micro-heater substrate wafer; the drying temperature is 75-85° C., and the drying time is 0.5-1.5 h.

8. The method for preparing the chlorobenzene sensor according to claim 1, characterized in that: In S4, the heat treatment time is 2.5-3.5 hours.

9. A chlorobenzene sensor, characterized in that: The chlorobenzene sensor is prepared by the preparation method of any one of claims 1 to 8.

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