A hydrogen sulfide gas sensor and its preparation process

Abstract

The invention belongs to the technical field of sensors, and discloses a hydrogen sulfide gas sensor and a preparation process thereof, comprising: preparing a MEMS micro-heating plate; providing powdered porous graphene nanosheets and dispersing them in deionized water, adding H2O2 solution for stirring, extracting and purifying by centrifugation, and dispersing them in ionized water to obtain porous graphene nanosheet ink; preparing gas-sensitive material ink, and sequentially dispensing the gas-sensitive material ink and graphene nanosheet ink on a detection electrode to obtain a hydrogen sulfide gas sensor; the porous graphene material increases the specific surface area of ​​the sensor and improves the gas adsorption capacity, and also selects analytes through its porous pore size, and analytes larger than or smaller than the pore size will be prevented from reaching the sensor, and the unique porous structure improves the selectivity and sensitivity of the sensor to H2S; NiO modifies Pt-doped ZnO gas-sensitive materials, improves the sensitivity of the H2S gas sensor, and reduces the dependence of the H2S gas sensor on humidity.

Description

Technical Field

[0001] The present invention relates to the technical field of sensors, and in particular to a hydrogen sulfide gas sensor and a preparation process thereof. Background Art

[0002] Hydrogen sulfide (H2S) is the main cause of bad breath problems, and monitoring of hydrogen sulfide concentration is also a key indicator for oral health testing; usually, halitosis is diagnosed as a person with a H2S concentration between 0.1–0.5 ppm in the breath. The detection of trace H2S is of great significance in diagnosing oral health status and alleviating halitosis. In order to accurately measure the H2S concentration in exhaled gas, several standardized methods have been developed, such as gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography, and proton transfer reaction mass spectrometry (PTR-MS), which have high sensitivity and accuracy, but are bulky, complex to operate, costly, and time-consuming, which limits the application of standard measurement methods. Therefore, small-volume, fast-response, and sensitive gas sensors have entered the user's field of vision.

[0003] The hydrogen sulfide (H2S) gas sensor in the prior art is an electrical measuring device that can generate an electrical signal in the presence of a target gas. So far, a variety of gas sensors have been used to detect H2S gas, including infrared optics, electrochemistry, semiconductors, catalytic combustion and surface acoustic waves. Among the various detection technologies used for H2S monitoring, chemical resistance gas sensors based on semiconductor metal oxides (SMO) are widely favored due to their high sensitivity, high detection limit and small size. However, the problem with chemical resistance gas sensors based on SMO is that they have poor selectivity for the type of target gas, resulting in the inability to accurately screen out the target gas when the concentration of the interferent detected is much higher than that of the target gas, resulting in poor detection accuracy. In addition, during breath detection, they are easily affected by environmental humidity, resulting in low detection accuracy.

[0004] In view of this, it is necessary to improve the hydrogen sulfide (H2S) gas sensor in the prior art to solve the technical problem of poor gas selectivity. Summary of the invention

[0005] The purpose of the present invention is to provide a hydrogen sulfide gas sensor and a preparation process thereof to solve the above technical problems.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] A preparation process of a hydrogen sulfide gas sensor, comprising:

[0008] Prepare a MEMS micro-heating plate, wherein the upper surface of the MEMS micro-heating plate has a detection electrode;

[0009] Powdered porous graphene nanosheets are dispersed in deionized water and added with H 2 O 2 The solution is stirred to form porous graphene nanosheets;

[0010] Purifying the porous graphene nanosheets by centrifugal extraction, dispersing the purified porous graphene nanosheets in ionized water to obtain porous graphene nanosheet ink;

[0011] Weighing a preset mass of zinc oxide and nickel oxide, mixing and grinding, to prepare a gas-sensitive material ink;

[0012] The gas-sensitive material ink and the graphene nanosheet ink are sequentially dispensed on the detection electrode to obtain a hydrogen sulfide gas sensor.

[0013] Optionally, the preparation of the MEMS micro-heating plate specifically includes:

[0014] choose <100> An oriented p-type silicon wafer is ultrasonically cleaned with acetone, isopropanol, ethanol, and deionized water in sequence, and dried with nitrogen to obtain a substrate layer;

[0015] A 1 μm thick silicon nitride layer is deposited on the substrate layer by low pressure chemical vapor deposition technology, wherein the silicon nitride layer forms a support layer; the support layer comprises a support layer body and a plurality of cantilever beams arranged on the side of the support layer body;

[0016] Patterning is performed on the surface of the support layer body by using UV photolithography technology, and then a first platinum layer with a thickness of 200 nm is deposited by a magnetron sputtering method, and the first platinum layer is removed by using a lift-off process, wherein the first platinum layer forms a heating electrode;

[0017] Depositing a 300-600 nm thick silicon nitride layer on the heating electrode using plasma enhanced chemical vapor deposition technology, wherein the silicon nitride layer forms an insulating layer;

[0018] UV photolithography technology is again used to form another patterned electrode pattern on the insulating layer, and then a second platinum layer with a thickness of 200 nm is deposited by a magnetron sputtering method, and the resist is removed by a lift-off process, and the second platinum layer forms a detection electrode.

[0019] Optionally, the method of preparing the MEMS micro-heating plate further includes:

[0020] The surface of the detection electrode layer is patterned again using UV photolithography technology, and then the support layer and the insulating layer are etched using inductively coupled plasma etching technology to expose the pad and etching window of the heating electrode;

[0021] The substrate layer is etched with a KOH solution to form a hollow groove below the support layer, so that the cantilever beam is suspended above the hollow groove to obtain a semi-finished chip;

[0022] The chip semi-finished product is cleaned with ionized water and dried with nitrogen to obtain a MEMS micro-heating plate.

[0023] Optionally, the purification of the porous graphene nanosheets by centrifugal extraction specifically includes:

[0024] The porous graphene nanosheets are purified once by a centrifuge at a rotation speed of 6000-10000 rpm, and the graphene oxide nanosheets after the once purification are dispersed in ionized water to obtain a primary purified product;

[0025] The initially purified product is added to the centrifuge again for secondary purification to obtain purified porous graphene nanosheets.

[0026] Optionally, the step of weighing a preset mass of zinc oxide and nickel oxide, mixing and grinding them to prepare a gas-sensitive material ink specifically includes:

[0027] Preset masses of zinc oxide and nickel oxide nanoparticles are weighed and mixed, ground in a mortar for a preset time, and then sintered in a muffle furnace at 600° C. for 2 h to obtain nickel oxide-modified zinc oxide nanoparticles;

[0028] The nickel oxide modified zinc oxide nanoparticles and zirconium oxide ball milling beads are added into a ball mill jar, and chloroplatinic acid and ethylene glycol or ethanol solution are added, and the gas sensitive material ink is obtained after ball milling for a preset time.

[0029] Optionally, the gas-sensitive material ink and the graphene nanosheet ink are sequentially dispensed on the detection electrode to obtain a hydrogen sulfide gas sensor; and then the method further includes:

[0030] Cooling the hydrogen sulfide gas sensor to room temperature and drying;

[0031] The cooled hydrogen sulfide gas sensor is sintered at a temperature ranging from 200° C. to 400° C. for a preset time to obtain a finished hydrogen sulfide gas sensor.

[0032] Optionally, the step of providing powdered porous graphene nanosheets dispersed in deionized water may also include:

[0033] According to the composition information of the gas to be detected, prepare H 2 O 2 Solution.

[0034] Optionally, the H2O2 of a preset concentration is prepared according to the composition information of the user's exhaled gas. 2 O 2 The solution specifically comprises:

[0035] According to the composition information of the gas to be detected, the size distribution information of the gas molecules to be detected is determined, and the chemical activity of the gas is evaluated;

[0036] Determine the ideal pore size data of porous graphene nanosheets based on the size distribution information of molecules and the chemical activity of gases;

[0037] Construct a concentration analysis model and establish H 2 O 2 The parameter relationship between concentration and pore size is obtained by using the ideal pore size data to obtain H 2 O 2 Concentration information;

[0038] According to H 2 O 2 The concentration information of H 2 O 2 Solution.

[0039] The present invention also provides a hydrogen sulfide gas sensor, which is manufactured using the above-mentioned manufacturing process for the hydrogen sulfide gas sensor, and the hydrogen sulfide gas sensor comprises:

[0040] A MEMS micro-heating plate, the MEMS micro-heating plate comprising a substrate layer, a support layer, a heating electrode, an insulating layer and a detection electrode sequentially stacked on the substrate layer;

[0041] A gas-sensitive material ink layer is provided on the upper surface of the detection electrode and is used for performing a gas-sensitive reaction on hydrogen sulfide gas while blocking the interference of water molecules;

[0042] The porous graphene nanosheet ink layer is arranged on the gas-sensitive material ink layer and is used for screening gas molecules of the gas to be detected.

[0043] Optionally, a hollow groove is formed on the substrate layer; the support layer includes a support layer body and a plurality of cantilever beams disposed on the side of the support layer body;

[0044] Two ends of the cantilever beam are respectively connected to the supporting layer body and the substrate layer.

[0045] Compared with the prior art, the present invention has the following beneficial effects: firstly, a MEMS micro-heating plate is prepared by using a MEMS process, thereby reducing the size and power consumption of the sensor; porous graphene nanosheets and gas-sensitive materials of zinc oxide and nickel oxide are used to effectively improve the performance of the hydrogen sulfide gas sensor; the introduction of porous graphene nanosheet ink not only increases the specific surface area of ​​the sensor and improves the gas adsorption capacity, but also selects the analyte through its porous pore size, and analytes larger than or smaller than the pore size will be prevented from reaching the sensor, and the unique porous structure improves the selectivity and sensitivity of the sensor to H2S; the zinc oxide gas-sensitive material modified with nickel oxide further enhances the selectivity of the sensor to the target gas and reduces the influence of environmental humidity on the sensor performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0047] The structures, proportions, sizes, etc. illustrated in the drawings of this specification are only used to match the contents disclosed in the specification so as to facilitate understanding and reading by persons familiar with this technology. They are not used to limit the conditions under which the present invention can be implemented, and therefore have no substantive technical significance. Any structural modification, change in proportion or adjustment of size, without affecting the effects and purposes that can be achieved by the present invention, should still fall within the scope of the technical contents disclosed by the present invention.

[0048] Figure 1 This is one of the flow diagrams of the preparation process of the hydrogen sulfide gas sensor of the first embodiment;

[0049] Figure 2 The third schematic diagram is a process flow diagram of the preparation process of the hydrogen sulfide gas sensor of the first embodiment;

[0050] Figure 3 This is a schematic diagram of the structure of the hydrogen sulfide gas sensor of the second embodiment;

[0051] Figure 4 is a schematic diagram of a response curve of the hydrogen sulfide gas sensor of the second embodiment;

[0052] Figure 5 It is a selective schematic diagram of the gas sensor of the hydrogen sulfide gas sensor of the second embodiment. DETAILED DESCRIPTION

[0053] In order to make the purpose, features and advantages of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described below are only 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.

[0054] In the description of the present invention, it should be understood that the terms "upper", "lower", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation of the present invention. It should be noted that when a component is considered to be "connected" to another component, it may be directly connected to the other component or there may be a centrally arranged component at the same time.

[0055] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0056] Embodiment 1:

[0057] Combination Figure 1 to Figure 2 As shown, an embodiment of the present invention provides a preparation process of a hydrogen sulfide gas sensor, comprising:

[0058] S1, preparing a MEMS micro-heating plate, wherein the upper surface of the MEMS micro-heating plate has a detection electrode 50;

[0059] The preparation of the MEMS micro-heating plate is the basis of the entire sensor preparation process. This step involves manufacturing a micro-heating plate with a detection electrode 50 on the upper surface; the detection electrode 50 is not only responsible for collecting the sensing signal, but also serves as a carrier of the gas-sensitive material and porous material of the sensor; during the processing, the accurate layout and functionality of the electrode need to be guaranteed.

[0060] S2, providing powdered porous graphene nanosheets dispersed in deionized water, and adding H 2 O 2 The solution is stirred to form porous graphene nanosheets;

[0061] Using H 2 O 2 The solution is regulated to generate a porous graphene nanosheet. This porous structure increases the specific surface area of ​​graphene, which is beneficial to improving its ability to adsorb hydrogen sulfide gas. 2 O 2As an oxidant, it helps to form a porous structure; and by controlling H 2 O 2 The concentration of the porous structure can be used to change the pore size.

[0062] S3, purifying the porous graphene nanosheets by centrifugal extraction, dispersing the purified porous graphene nanosheets into ionized water to obtain porous graphene nanosheet ink;

[0063] Centrifugation was used to remove unreacted H 2 O 2 and other possible impurities, the purification process ensures the purity and quality of the porous graphene nanosheets; high-purity porous graphene nanosheets are crucial to improving the sensitivity and stability of the sensor.

[0064] S4, weighing a preset mass of zinc oxide and nickel oxide, mixing and grinding, and preparing a gas-sensitive material ink;

[0065] A mixture of zinc oxide (ZnO) and nickel oxide (NiO) is used as a gas-sensitive material, which combines the advantages of two metal oxides to form a special interface or heterojunction, thereby enhancing the detection sensitivity of H2S; the grinding process enhances the connection and uniform distribution of the two materials.

[0066] S5, dispensing the gas-sensitive material ink and the graphene nanosheet ink on the detection electrode 50 in sequence to obtain a hydrogen sulfide gas sensor.

[0067] The key to this step is to accurately dispense the inks of the two materials onto the detection electrode 50 of the micro-heating plate. This process determines the uniformity and thickness of the sensing layer, which directly affects the performance of the sensor. By accurately controlling the dispensing process, it can be ensured that the prepared hydrogen sulfide gas sensor has high sensitivity and good repeatability.

[0068] In summary, the entire preparation process fully utilizes the unique properties of porous graphene nanosheets and zinc oxide-nickel oxide composite materials, and through fine process control, a high-performance gas sensor for hydrogen sulfide detection is successfully constructed. By utilizing the increased specific surface area of ​​porous graphene and the specific reactivity of metal oxides, this sensor is expected to provide higher sensitivity, better selectivity and faster response speed in practical applications.

[0069] The working principle of the present invention is as follows: when working, a MEMS micro-heating plate is first prepared to provide a substrate for the subsequent precise loading of materials and a heat source; powdered graphene oxide nanosheets are dispersed in deionized water and a preset concentration of H is added. 2 O 2The solution is stirred to prepare graphene oxide nanosheets, which are further purified by centrifugal extraction to finally obtain porous graphene nanosheet ink; at the same time, preset masses of zinc oxide and nickel oxide are mixed and ground to prepare gas-sensitive material ink; finally, the prepared gas-sensitive material ink and porous graphene nanosheet ink are sequentially dispensed on the detection electrode 50 of the MEMS micro-heating plate to construct a hydrogen sulfide gas sensor; this scheme effectively improves the performance of the hydrogen sulfide gas sensor by comprehensively utilizing porous graphene nanosheets and gas-sensitive materials of zinc oxide and nickel oxide; porous graphene nanosheet ink The introduction of not only increases the specific surface area of ​​the sensor and improves the gas adsorption capacity, but also selects the analytes through its porous pore size. Analytes larger or smaller than the pore size will be prevented from reaching the sensor. The unique porous structure improves the selectivity and sensitivity of the sensor to H2S; the zinc oxide gas-sensitive material modified with nickel oxide further enhances the selectivity of the sensor for the target gas and reduces the influence of ambient humidity on the sensor performance, thereby effectively solving the problems of common sensors in selectivity, sensitivity and resistance to environmental disturbances, and providing a strong guarantee for the high-precision detection of H2S gas.

[0070] In this embodiment, it is specifically described that, in combination with Figure 2 As shown, step S1 specifically includes:

[0071] S11, select <100> An oriented p-type silicon wafer is ultrasonically cleaned with acetone, isopropanol, ethanol, and deionized water in sequence, and dried with nitrogen to obtain a substrate layer 10;

[0072] By choosing <100> The oriented p-type silicon wafer is used as the base substrate and is ultrasonically cleaned in sequence with acetone, isopropanol, ethanol and deionized water, and then blown dry with nitrogen to ensure that the substrate surface is clean and free of impurities, providing an ideal foundation for the deposition of subsequent layers.

[0073] S12, depositing a 1 μm thick silicon nitride layer on the substrate layer 10 by low pressure chemical vapor deposition technology, the silicon nitride layer forming a support layer 20; the support layer 20 includes a support layer 20 body, and a plurality of cantilever beams arranged on the side of the support layer 20 body;

[0074] A 1 μm thick silicon nitride layer is deposited on a cleaned silicon wafer using low pressure chemical vapor deposition (LPCVD) technology to form a support layer 20. This support layer 20 not only provides physical support for subsequent layers, but also includes cantilever beams on the sides, which are designed to support the sensing elements and enhance the stability and reliability of the structure.

[0075] S13, patterning the surface of the support layer 20 by UV photolithography technology, then depositing a first platinum layer with a thickness of 200 nm by magnetron sputtering, and removing the adhesive by lift-off process, so that the first platinum layer forms the heating electrode 30;

[0076] The electrode pattern is formed on the support layer 20 by UV photolithography, and then a 200 nm thick platinum layer is deposited by magnetron sputtering to form the heating electrode 30. Platinum is selected for its excellent electrical conductivity and chemical stability. The design and manufacture of the heating electrode 30 are crucial to the heating efficiency and uniformity of the sensor.

[0077] S14, using plasma enhanced chemical vapor deposition technology to deposit a 300-600 nm thick silicon nitride layer on the heating electrode 30, the silicon nitride layer forming the insulating layer 40; wherein the preferred thickness of the silicon nitride layer is 450 nm;

[0078] A 300-600 nm thick silicon nitride layer is deposited on the heating electrode 30 using plasma enhanced chemical vapor deposition (PECVD) technology to form an insulating layer 40. This layer is used to prevent electrical short circuits between electrodes and ensure electrical isolation between the heating electrode 30 and the detection electrode 50.

[0079] S15, UV photolithography is again used to form another patterned electrode pattern on the insulating layer 40, and then a second platinum layer with a thickness of 200 nm is deposited by magnetron sputtering, and a lift-off process is used to remove the resist, and the second platinum layer forms the detection electrode 50.

[0080] UV lithography is again used to form an electrode pattern on the insulating layer 40, and a second platinum layer is deposited by magnetron sputtering to form a detection electrode 50; the detection electrode 50 is used to capture the resistance change caused by the target gas, and its precise preparation is crucial to the performance of the sensor.

[0081] S16, patterning the surface of the detection electrode layer 50 again by using UV photolithography technology, and then etching the support layer 20 and the insulating layer 40 by using inductively coupled plasma etching technology to expose at least a portion of the heating electrode 30 to form a pad;

[0082] The support layer 20 and the insulating layer 40 are precisely etched using inductively coupled plasma (ICP) etching technology to expose the pads and etching windows (partial silicon substrate) of the heating electrode 30. This step provides an interface for subsequent electrical connections. The etching window portion is used for etching to form a hollow groove 11.

[0083] S17, etching the substrate layer 10 with a KOH solution to form a hollow groove 11 below the support layer 20, so that the cantilever beam is suspended above the hollow groove 11, and a chip semi-finished product is obtained;

[0084] The substrate layer 10 is wet-etched using a KOH solution to form a hollow groove 11 under the support layer 20, which makes the cantilever beam partially suspended, thereby reducing heat loss and improving heating efficiency; at the same time, it plays a role in air convection, thereby playing a role in heat dissipation for electronic components. This step is crucial to ensure the thermal management of the MEMS micro-heating plate and the sensor response speed.

[0085] S18, the chip semi-finished product is cleaned with ionized water and dried with nitrogen to obtain a MEMS micro-heating plate, thereby ensuring the cleanliness and drying of the micro-heating plate and preparing the substrate for the subsequent gas-sensitive material ink dispensing step.

[0086] In this embodiment, it is specifically described that the porous graphene nanosheets are purified by centrifugal extraction, which specifically includes:

[0087] The porous graphene nanosheets are purified once by a centrifuge at a rotation speed of 6000-10000 rpm, and the graphene oxide nanosheets purified once are dispersed in ionized water to obtain a primary purified product;

[0088] It should be noted that the porous graphene nanosheets were first purified by centrifugation, using a centrifuge operated at a speed of 6000-10000 rpm; the purpose of this process is to remove unreacted substances, impurities and excess H in the nanosheets. 2 O 2 , which is beneficial to improve the performance and purity of the nanosheets. The product after primary purification is dispersed in deionized water to form a primary purified product in preparation for secondary purification.

[0089] The initially purified product is added to the centrifuge again for secondary purification to obtain purified porous graphene nanosheets.

[0090] The initial purified product is centrifuged again to further improve the purity of the nanosheets. Repeated purification processes can more effectively remove residual impurities and unreacted products, ensuring that higher purity porous graphene nanosheets are obtained. This is crucial to improving the sensitivity and selectivity of the sensor to hydrogen sulfide gas, as impurities and unreacted products may interfere with the sensor's response.

[0091] In summary, in this preparation process, two centrifugal purifications of porous graphene nanosheets are key steps to ensure the quality of the material. Such a purification process helps to remove impurities and unreacted substances that may have an adverse effect on sensor performance. In this way, pure and stable porous graphene nanosheets can be obtained, thereby improving the performance of the final hydrogen sulfide gas sensor.

[0092] In this embodiment, it is specifically described that step S4 specifically includes:

[0093] S41, weighing a preset mass of zinc oxide and nickel oxide nanoparticles, mixing them, grinding them in a mortar for a preset time, and then sintering the ground material in a muffle furnace at 600° C. for 2 h to obtain nickel oxide-modified zinc oxide nanoparticles;

[0094] This step prepares nickel oxide modified zinc oxide nanoparticles by mixing zinc oxide and nickel oxide nanoparticles, grinding and sintering. Zinc oxide (ZnO) is an n-type semiconductor material, while nickel oxide (NiO) is a p-type semiconductor material. The combination of the two can form a pn heterojunction, which can effectively improve the charge transfer efficiency and increase the sensitivity to hydrogen sulfide. In addition, the formation of the pn heterojunction helps to regulate the interface effect, thereby reducing the impact of humidity on sensor performance.

[0095] Through the grinding and sintering process, not only can the two materials be mixed evenly, but the crystallinity of the material can also be improved through the sintering process, and its microstructure can be further optimized. This is very important for improving the performance of gas-sensitive materials.

[0096] S42, adding nickel oxide modified zinc oxide nanoparticles and zirconium oxide ball milling beads into a ball mill jar, adding chloroplatinic acid and ethylene glycol or ethanol solution, and ball milling for a preset time to obtain a gas sensitive material ink.

[0097] In this step, the nickel oxide modified zinc oxide nanoparticles are ball milled with zirconium oxide ball milling beads to further refine the size of the nanoparticles and improve their dispersibility. Chloroplatinic acid and ethylene glycol (or ethanol) solution are added, where chloroplatinic acid is used as a catalyst to improve the adsorption and reaction activity of hydrogen sulfide gas, and ethylene glycol or ethanol is used as a solvent to help form a uniform gas-sensitive material ink.

[0098] The chloroplatinic acid added during the ball milling process, as a catalyst, not only enhances the sensitivity of the material to hydrogen sulfide, but also may improve the overall performance of the sensor through its catalytic effect. In addition, the introduction of NiO not only improves the sensitivity by forming a pn heterojunction, but also can effectively block the direct interaction between ZnO material and water molecules due to its high hydrophilicity, which is an important advantage for sensors used in environments with large humidity changes.

[0099] In summary, by modifying zinc oxide with nickel oxide and combining chloroplatinic acid as a catalyst, this embodiment not only successfully improved the sensitivity of the hydrogen sulfide gas sensor, but also effectively improved its dependence on humidity. This method fully demonstrates that the performance of gas sensors can be significantly improved through material engineering and surface modification technology, especially in applications that are sensitive to environmental conditions. By forming a pn heterojunction and optimizing the microstructure and chemical properties of the sensing material,

[0100] In this embodiment, it is further explained that after step S5, the following steps are further included:

[0101] S6, cooling the hydrogen sulfide gas sensor to room temperature and drying;

[0102] In the preparation process of hydrogen sulfide gas sensor, cooling to room temperature after dispensing is a necessary step to stabilize the material on the sensor and avoid cracks or structural damage caused by rapid temperature changes. Drying is then performed to remove residual solvents and moisture on the surface or inside the sensor; this step is critical to ensure the adhesion and structural integrity of the sensor material.

[0103] S7, sintering the cooled hydrogen sulfide gas sensor at a temperature ranging from 200° C. to 400° C. for a preset time to obtain a finished hydrogen sulfide gas sensor.

[0104] The sintering step is carried out in the range of 200°C to 400°C, with the aim of enhancing the structural stability and durability of the sensor material through temperature treatment. Sintering within this temperature range can optimize the combination of the gas-sensitive material and the porous graphene nanosheets, as well as the crystal structure within the material, thereby improving the sensor's responsiveness and stability to hydrogen sulfide gas. The preset sintering time depends on the required adjustment of the material properties. Too short a time may not be enough to form a stable microstructure, while too long a time may cause the material to be over-sintered, affecting its performance.

[0105] In this embodiment, as a preferred embodiment of this solution, powdered porous graphene nanosheets are dispersed in deionized water, and the method also includes:

[0106] S20, preparing H with a preset concentration according to the composition information of the gas to be detected 2 O 2 solution. Due to different concentrations of H 2 O 2 The solution can change the pore size of the porous graphene nanosheets, thereby changing the gas selectivity of the final porous graphene nanosheet ink layer 70; the purpose is to customize a hydrogen sulfide gas sensor with good sensitivity and selectivity according to the composition of the gas to be detected.

[0107] In this embodiment, as a preferred solution of this embodiment, step S20 specifically includes:

[0108] S201, determining size distribution information of the gas molecules to be detected based on the composition information of the gas to be detected, and evaluating the chemical activity of the gas;

[0109] First, the components of the gas to be detected are preliminarily measured through gas determination experiments, and the size information of the gas molecules to be detected is collected through experimental data, the chemical properties of the gas to be detected are analyzed, and whether it is likely to undergo chemical reactions when in contact with porous graphene nanosheets is evaluated. Chemical activity evaluation can be based on literature data or obtained through pilot experiments.

[0110] S202, determining ideal pore size data of the porous graphene nanosheet according to the size distribution information of the molecules and the chemical activity of the gas;

[0111] Based on the size and chemical activity of the gas molecules, the most suitable pore size of the porous graphene nanosheet for detection is determined. The ideal pore size should allow gas molecules to enter and exit smoothly while maximizing the contact area with the graphene nanosheet. Considering the molecular size distribution, a range of pore sizes may need to be considered to accommodate the variation in molecular size and optimize the responsiveness and selectivity of the sensor.

[0112] S203, build a concentration analysis model and establish H 2 O 2 The parameter relationship between concentration and pore size is obtained by using the ideal pore size data to obtain H 2 O 2 Concentration information;

[0113] First, a concentration analysis model is constructed using computational chemistry or artificial intelligence (machine learning / deep learning) methods to predict H 2 O 2 Effect of concentration on pore size.

[0114] Through experimental data or simulation data, establish H 2 O 2 The mathematical relationship between concentration and pore size of porous graphene nanosheets. This relationship can be linear or nonlinear, depending on the data collected.

[0115] Using the model constructed in the previous step and the determined parameter relationship, input the ideal aperture size data and calculate the corresponding H 2 O 2 Concentration information.

[0116] S204, according to H 2 O 2 The concentration information of H 2 O 2 Solution.

[0117] It is further explained that step S203 specifically includes:

[0118] S2031, according to the experimental determination method, obtain multiple groups of H with different concentrations 2O 2 Solution, using multiple groups of different concentrations of H 2 O 2 The solutions are used to treat the powdered porous graphene nanosheets respectively to obtain a plurality of groups of corresponding porous graphene nanosheets;

[0119] Prepare multiple H solutions with different concentrations according to the preset concentration range. 2 O 2 Solutions, these concentrations should cover the range from very dilute to relatively concentrated to ensure that significant pore size changes can be observed. 2 O 2 The solution was used to treat multiple groups of powdered porous graphene nanosheets. Each group of nanosheets should be treated with a specific concentration of H 2 O 2 The samples were treated in the same solution for the same time to ensure consistent treatment conditions.

[0120] S2032, using a scanning electron microscope to measure the pore size of each group of porous graphene nanosheets to obtain actual pore size distribution information.

[0121] S2033, according to multiple groups H 2 O 2 The concentration information of the solution and the corresponding actual pore size distribution information are used to establish an analysis chart;

[0122] The H of each sample 2 O 2 The concentration and corresponding pore size distribution information are summarized and a series of analytical charts are drawn using the collected data; the analytical charts should clearly show the different H 2 O 2 Changes in the pore size of porous graphene nanosheets under concentration.

[0123] S2034, input the data of the analysis chart into the concentration analysis model, and establish H in the concentration analysis model. 2 O 2 Parametric relationship between concentration and pore size;

[0124] According to the characteristics of the data, a suitable concentration analysis model framework is selected, which may be a linear regression, a polynomial regression, or a machine learning model. The data collated in step S2033 is input into the selected model framework, and training is performed, and the accuracy and predictive ability of the model are verified using cross-validation and other techniques.

[0125] S2035, input the ideal pore size data into the concentration analysis model to obtain H 2 O 2 Concentration information;

[0126] According to the size distribution information of the gas molecules to be detected, the ideal pore size is input into the model. The model will predict the appropriate H 2 O 2 This predicted concentration should enable the porous graphene nanosheets to reach the desired pore size after treatment.

[0127] Embodiment 2:

[0128] The present invention also provides a hydrogen sulfide gas sensor, characterized in that it is prepared by using the preparation process of the hydrogen sulfide gas sensor of embodiment 1, combined with Figure 3 As shown, the hydrogen sulfide gas sensor includes:

[0129] The MEMS micro-heating plate comprises a substrate layer 10, a support layer 20, a heating electrode 30, an insulating layer 40 and a detection electrode 50 sequentially stacked on the substrate layer 10;

[0130] The gas-sensitive material ink layer 60 is disposed on the upper surface of the detection electrode 50 and is used for performing a gas-sensitive reaction to hydrogen sulfide gas while blocking the interference of water molecules.

[0131] The porous graphene nanosheet ink layer 70 is disposed on the gas-sensitive material ink layer 60 and is used for screening gas molecules of the gas to be detected.

[0132] It should be noted that, combined with Figure 4 and Figure 5 As shown, in order to verify the performance of the hydrogen sulfide gas sensor, corresponding experimental measurements are performed on the hydrogen sulfide gas sensor to measure the sensor's response performance to hydrogen sulfide and its selectivity to multiple gases.

[0133] It is further explained that a hollow groove 11 is opened on the substrate layer 10; the support layer 20 includes a support layer 20 body and a plurality of cantilever beams arranged on the side of the support layer 20 body; the two ends of the cantilever beam are respectively connected to the support layer 20 body and the substrate layer 10.

[0134] As described above, 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 thereof 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 preparation process of a hydrogen sulfide gas sensor, characterized in that: include: Prepare a MEMS micro-heating plate, wherein the upper surface of the MEMS micro-heating plate has a detection electrode; Providing a powdered porous graphene nanosheet dispersed in deionized water, and adding a H2O2 solution of a preset concentration and stirring to form a porous graphene nanosheet; Purifying the porous graphene nanosheets by centrifugal extraction, dispersing the purified porous graphene nanosheets in ionized water to obtain porous graphene nanosheet ink; Weighing a preset mass of zinc oxide and nickel oxide, mixing and grinding, to prepare a gas-sensitive material ink; Dispensing the gas-sensitive material ink and the graphene nanosheet ink on the detection electrode in sequence to obtain a hydrogen sulfide gas sensor; Wherein, the step of providing powdered porous graphene nanosheets dispersed in deionized water also includes: According to the composition information of the gas to be detected, prepare a H2O2 solution of a preset concentration; The step of preparing a H2O2 solution of a preset concentration according to the composition information of the gas to be detected specifically includes: According to the composition information of the gas to be detected, the size distribution information of the gas molecules to be detected is determined, and the chemical activity of the gas is evaluated; Determine the ideal pore size data of porous graphene nanosheets based on the size distribution information of molecules and the chemical activity of gases; Construct a concentration analysis model and establish the parameter relationship between H2O2 concentration and pore size, and obtain H2O2 concentration information through ideal pore size data; Prepare H2O2 solution of corresponding concentration according to H2O2 concentration information; The method of constructing a concentration analysis model and establishing a parameter relationship between H2O2 concentration and pore size, and obtaining H2O2 concentration information through ideal pore size data, specifically includes: S2031, obtaining multiple groups of H2O2 solutions with different concentrations according to an experimental determination method, and using the multiple groups of H2O2 solutions with different concentrations to treat the powdered porous graphene nanosheets respectively to obtain multiple groups of corresponding porous graphene nanosheets; S2032, using a scanning electron microscope to measure the pore size of each group of porous graphene nanosheets to obtain actual pore size distribution information; S2033, establishing an analysis chart based on the concentration information of the multiple groups of H2O2 solutions and the corresponding actual pore size distribution information; S2034, inputting the data of the analysis chart into the concentration analysis model, and establishing a parameter relationship between H2O2 concentration and pore size in the concentration analysis model; S2035, inputting the ideal pore size data into the concentration analysis model to obtain H2O2 concentration information; Wherein, the preparation of the MEMS micro-heating plate specifically includes: choose <100> An oriented p-type silicon wafer is ultrasonically cleaned with acetone, isopropanol, ethanol, and deionized water in sequence, and dried with nitrogen to obtain a substrate layer; A 1 μm thick silicon nitride layer is deposited on the substrate layer by low pressure chemical vapor deposition technology, wherein the silicon nitride layer forms a support layer; the support layer comprises a support layer body and a plurality of cantilever beams arranged on the side of the support layer body; Patterning is performed on the surface of the support layer body by using UV photolithography technology, and then a first platinum layer with a thickness of 200 nm is deposited by a magnetron sputtering method, and the first platinum layer is removed by a lift-off process, wherein the first platinum layer forms a heating electrode; Depositing a 300-600 nm thick silicon nitride layer on the heating electrode using plasma enhanced chemical vapor deposition technology, wherein the silicon nitride layer forms an insulating layer; Another electrode pattern is formed on the insulating layer by UV photolithography again, and then a second platinum layer with a thickness of 200 nm is deposited by magnetron sputtering, and the second platinum layer is removed by lift-off process, so that the detection electrode is formed; The surface of the detection electrode layer is patterned again using UV photolithography technology, and then the support layer and the insulating layer are etched using inductively coupled plasma etching technology to expose the pad and etching window of the heating electrode; The substrate layer is etched with a KOH solution to form a hollow groove below the support layer, so that the cantilever beam is suspended above the hollow groove to obtain a semi-finished chip; The chip semi-finished product is cleaned with ionized water and dried with nitrogen to obtain a MEMS micro-heating plate.

2. The preparation process of the hydrogen sulfide gas sensor according to claim 1, characterized in that: The method of purifying the porous graphene nanosheets by centrifugal extraction specifically comprises: The porous graphene nanosheets are purified once by a centrifuge at a rotation speed of 6000-10000 rpm, and the porous graphene nanosheets after the purification are dispersed in ionized water to obtain a primary purified product; The initially purified product is added to the centrifuge again for secondary purification to obtain purified porous graphene nanosheets.

3. The preparation process of the hydrogen sulfide gas sensor according to claim 1, characterized in that: The step of weighing a preset mass of zinc oxide and nickel oxide, mixing and grinding them to prepare a gas-sensitive material ink specifically comprises: Preset masses of zinc oxide and nickel oxide nanoparticles are weighed and mixed, ground in a mortar for a preset time, and then sintered in a muffle furnace at 600° C. for 2 h to obtain nickel oxide-modified zinc oxide nanoparticles; The nickel oxide modified zinc oxide nanoparticles and zirconium oxide ball milling beads are added into a ball mill jar, and chloroplatinic acid and ethylene glycol or ethanol solution are added, and the gas sensitive material ink is obtained after ball milling for a preset time.

4. The preparation process of the hydrogen sulfide gas sensor according to claim 1, characterized in that: The gas-sensitive material ink and the graphene nanosheet ink are sequentially dispensed on the detection electrode to obtain a hydrogen sulfide gas sensor; and then further comprising: Cooling the hydrogen sulfide gas sensor to room temperature and drying; The cooled hydrogen sulfide gas sensor is sintered at a temperature ranging from 200° C. to 400° C. for a preset time to obtain a finished hydrogen sulfide gas sensor.

5. A hydrogen sulfide gas sensor, characterized in that: The hydrogen sulfide gas sensor is manufactured by the preparation process of any one of claims 1 to 4, wherein the hydrogen sulfide gas sensor comprises: A MEMS micro-heating plate, the MEMS micro-heating plate comprising a substrate layer, a support layer, a heating electrode, an insulating layer and a detection electrode sequentially stacked on the substrate layer; A gas-sensitive material ink layer is provided on the upper surface of the detection electrode and is used for performing a gas-sensitive reaction on hydrogen sulfide gas while blocking the interference of water molecules; The porous graphene nanosheet ink layer is arranged on the gas-sensitive material ink layer and is used for screening gas molecules of the gas to be detected.

6. The hydrogen sulfide gas sensor according to claim 5, characterized in that: The substrate layer is provided with a hollow groove; the support layer comprises a support layer body and a plurality of cantilever beams arranged on the side of the support layer body; Two ends of the cantilever beam are respectively connected to the supporting layer body and the substrate layer.

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