Acetone gas sensor based on bimetallic supported nanoparticles and method of preparation thereof

Abstract

The application provides a bimetallic nanoparticle-based acetone gas sensor and a preparation method thereof. The preparation method comprises the following steps: adding tin chloride into a solution containing a complexing agent and deionized water, stirring for 10 minutes at 60 DEG C, then adding ammonia water until the pH reaches 3, and obtaining a tin hydroxide precipitate powder after centrifugal washing; adding the tin hydroxide precipitate powder into indium trichloride tetrahydrate powder, gold chloride powder and platinum tetrachloride powder in sequence, and performing ball milling mixing, sintering at 600 DEG C for 2 hours, and obtaining bimetallic nanoparticle; adding ethylene glycol and zirconium oxide ball milling beads into the bimetallic nanoparticle, performing ball milling for 8 hours, obtaining a point glue solution, coating the point glue solution on a micro motor heating plate, drying at room temperature, and sintering at 200-400 DEG C for 3-4 hours, and obtaining the bimetallic nanoparticle-based acetone gas sensor. Therefore, the excitation temperature can be effectively reduced, and the selectivity to acetone gas can be improved.

Description

Technical Field

[0001] This invention belongs to the field of sensing technology, and particularly relates to an acetone gas sensor based on bimetallic loaded nanoparticles and its preparation method. Background Technology

[0002] Human exhaled breath contains approximately 3,500 volatile organic compounds (VOCs). Analysis of these VOCs in breath may become a promising non-invasive tool and a simple method for health checks, which can be performed both at home and in medical facilities for medical diagnosis and treatment monitoring. For example, breath analysis can be used for the early diagnosis of diseases such as lung cancer, congestive heart failure, diabetes, and asthma. Exhaled acetone is considered an important biomarker for type 1 diabetes. Diabetic patients have reportedly higher acetone concentrations (>1.8 ppm) compared to healthy individuals (0.3–0.9 ppm). Therefore, monitoring breath acetone could be considered a useful method for tracking patients' prescribed dietary regimens and monitoring diabetic patients. Furthermore, a correlation exists between acetone and blood glucose levels; therefore, its monitoring can be used for insulin management. Exhaled acetone concentrations can be measured using standardized methods such as gas chromatography-mass spectrometry (GC-MS), high-performance liquid chromatography (HPLC), and proton transfer reaction mass spectrometry (PTR-MS). These techniques offer high sensitivity and accuracy for detecting exhaled acetone concentrations. However, these methods are bulky, complex, expensive, and time-consuming. Therefore, there is a need for a small, portable, and fast device that can easily detect the concentration of acetone in exhaled breath.

[0003] A gas sensor is an electrical measuring device that generates an electrical signal in the presence of a target gas. To date, various gas sensors have been used to detect acetone, including infrared optical, electrochemical, semiconductor, catalytic combustion, and surface acoustic wave sensors. Among the various detection technologies used for acetone detection, chemiluminescence resistivity gas sensors based on semiconductor metal oxides (SMOs) are among the most promising candidates due to their high sensitivity, fast response, outstanding detection limit, simple operating mechanism, and ease of miniaturization. However, SMOs have several drawbacks in detecting acetone in exhaled breath. Firstly, the excitation temperature of the gas sensor is too high; to achieve sufficient reactivity, SMO sensors typically need to operate at temperatures above 400°C. This high temperature requirement not only increases energy consumption but also complicates heat dissipation and safety management for portable or wearable devices. Secondly, although SMO sensors are highly sensitive to acetone, respiration contains thousands of volatile organic compounds, and many other gases (such as methanol, ethanol, and isoprene) can interfere with the sensor. This cross-interference results in poor selectivity of the gas sensor for acetone, reducing detection accuracy and thus affecting the detection results. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an acetone gas sensor based on bimetallic loaded nanoparticles and its preparation method, aiming to solve the problems of excessively high excitation temperature and poor selectivity of acetone gas in gas sensors.

[0005] To solve the above-mentioned technical problems, the present invention is implemented as follows: The present invention proposes a method for preparing an acetone gas sensor based on bimetallic loaded nanoparticles, the steps of which include:

[0006] S1. Add tin chloride to a solution containing a complexing agent and deionized water, stir at 60°C for 10 minutes, then add ammonia until the pH reaches 3, centrifuge and wash to obtain tin hydroxide precipitate powder.

[0007] S2. Tin hydroxide precipitate powder is added sequentially to indium trichloride tetrahydrate powder, gold chloride powder and platinum tetrachloride powder and ball-milled and mixed. The mixture is then sintered at 600℃ for 2 hours to obtain bimetallic supported nanoparticles. The molar ratio is calculated as follows: tin hydroxide precipitate powder : indium trichloride tetrahydrate powder : gold chloride powder : platinum tetrachloride powder = (40~60) : (3~5) : 1 : 1.

[0008] S3. Ethylene glycol and zirconium oxide ball milling beads are added to the bimetallic loaded nanoparticles and ball milled for 8 hours to obtain a dispensing solution. The dispensing solution is coated on a micro-motor heating plate, dried at room temperature, and then sintered at 200~400℃ for 3~4 hours to obtain an acetone gas sensor based on bimetallic loaded nanoparticles.

[0009] In one embodiment, in step S1, the complexing agent includes citric acid and ethylenediaminetetraacetic acid, and the tin chloride includes at least one of tin tetrachloride and tin dichloride.

[0010] In one embodiment, step S1 includes:

[0011] S1.1 Add a complexing agent to high-purity deionized water with a resistivity ≥18.2MΩ·cm, set the temperature to 60℃, and control the stirring speed at 400~600rpm;

[0012] S1.2 Continue to add tin chloride, and keep the solution at 60°C while stirring for 10 minutes. While stirring continuously, titrate ammonia and surfactant until the solution pH reaches 3 to obtain a precipitate mixture. The surfactant includes at least one of sodium dodecyl sulfate and polyvinylpyrrolidone.

[0013] S1.3. The precipitate mixture is centrifuged at a speed of 5000-8000 rpm for 10-15 minutes. After centrifugation, it is washed and dried at 60-80°C to obtain tin hydroxide precipitate powder.

[0014] In one embodiment, step S2 includes:

[0015] S2.1 Add tin hydroxide precipitate powder, indium trichloride tetrahydrate powder, gold chloride powder and platinum tetrachloride powder to the ball mill in sequence, and add inert solvent. The speed is 400-500 rpm, the ball milling time is 3-4 hours, and inert gas is introduced during the ball milling process and the intermittent ball milling mode is set to stop for 10 minutes every 1 hour.

[0016] S2.2 Set the heating rate to 5℃ / min, raise the temperature to 600℃, maintain this temperature for 2 hours, apply ultraviolet light treatment after heating, cool down to room temperature, and control the cooling rate to within 5℃ / min to obtain bimetallic supported nanoparticles.

[0017] In one embodiment, in step S2.1, the inert solvent includes at least one of isopropanol, n-hexane, and toluene.

[0018] In one embodiment, step S3 includes:

[0019] S3.1, Select crystal orientation as <100> A 500μm thick p-type silicon wafer was ultrasonically cleaned sequentially with acetone, isopropanol, ethanol, and deionized water, and then dried with nitrogen to obtain a substrate.

[0020] S3.2. A 1 μm thick support layer is deposited on the substrate by chemical vapor deposition, and the support layer is exposed to ultraviolet light to obtain a heating electrode image. Then, a 200 nm thick heating electrode is deposited on the heating electrode image by magnetron sputtering.

[0021] S3.4. An insulating layer with a thickness of 450 nm is deposited on the heating electrode by plasma-enhanced chemical vapor deposition. The insulating layer is exposed to ultraviolet light to obtain an image of the detection electrode. Then, a detection electrode with a thickness of 200 nm is deposited on the detection electrode image by magnetron sputtering.

[0022] S3.5. The insulating layer and the support layer are simultaneously etched by inductively coupled plasma etching to expose the heating electrode;

[0023] S3.6. The silicon substrate is etched using potassium oxide solution, cleaned with deionized water, and dried with nitrogen to obtain a micro-motor heating plate.

[0024] S3.7. Mix the bimetallic supported nanoparticles with ethylene glycol, add zirconia grinding beads and ball mill, control the speed at 400-500 rpm, and ball mill for 8 hours to obtain the dispensing solution.

[0025] S3.8 The dispensing solution is uniformly deposited on the micro-motor heating plate by inkjet printing or screen printing. After deposition, it is sintered at 200℃~400℃ to obtain an acetone gas sensor based on bimetallic loaded nanoparticles.

[0026] In one embodiment, after step S3.8, the method further includes:

[0027] S3.9. In an air environment, heat the acetone gas sensor based on bimetallic loaded nanoparticles to 500°C, maintain it for 10 minutes, cool it to room temperature, and then irradiate it with ultraviolet light with a wavelength of 365nm or blue light with a wavelength of 450nm. The light intensity is controlled between 10 and 15mW / cm², and the irradiation treatment is continued for 20 minutes.

[0028] In one embodiment, the support layer includes at least one of silicon nitride, silicon dioxide, and aluminum oxide; the insulating layer includes at least one of silicon dioxide, silicon nitride, and polyimide; the heating electrode includes at least one of platinum, gold, and doped polycrystalline silicon; and the detection electrode includes at least one of platinum, gold, and palladium.

[0029] This invention proposes an acetone gas sensor based on bimetallic loaded nanoparticles, which is fabricated using a method described above. The acetone gas sensor based on bimetallic loaded nanoparticles comprises tin hydroxide precipitate powder, indium trichloride tetrahydrate powder, gold chloride powder, platinum tetrachloride powder, and a micro-motor heating plate; wherein,

[0030] The tin hydroxide precipitate powder is used as a gas-sensitive material for an acetone gas sensor.

[0031] The indium trichloride tetrahydrate powder is used to improve the sensitivity and selectivity of the acetone gas sensor to acetone gas;

[0032] The gold chloride powder promotes the adsorption and reaction of acetone molecules on the surface of the acetone gas sensor;

[0033] The platinum tetrachloride powder is used to synergistically catalyze the gold chloride powder to reduce the reaction activation energy;

[0034] The micro-motor heating plate is used to ensure that the acetone gas sensor is maintained within the optimal temperature range during operation.

[0035] Compared with existing technologies, the acetone gas sensor based on bimetallic loaded nanoparticles and its preparation method in this invention have the following advantages:

[0036] By incorporating indium trichloride tetrahydrate into tin hydroxide precipitate to form a mixed crystal or heterojunction structure, gold chloride and platinum tetrachloride are added sequentially. During sintering at 600℃, these precursors are transformed into a supported structure of oxides and metal nanoparticles (gold and platinum). The gold and platinum nanoparticles exhibit excellent catalytic activity, and their synergistic effect at the nanoscale effectively reduces the activation energy of acetone molecules reacting on the sensor surface. This lowers the energy required for the actual gas reaction of the sensing material, allowing the sensor to elicit sufficient gas-sensitive reactions at lower temperatures (200–400℃ or even lower). Low-temperature operation not only reduces energy consumption but also simplifies system heat dissipation design, making it suitable for portable and low-power applications. Furthermore, gold and platinum complement each other in the catalytic reaction; gold exhibits high catalytic activity towards volatile organic compounds, while platinum can modulate the charge transport characteristics and surface oxygen ion state of the sensing material. This bimetallic synergistic effect helps selectively promote the adsorption and reaction of acetone molecules while suppressing the reaction rates of other interfering gases. The improved specificity for acetone allows the sensor to detect acetone more accurately in complex exhaled gas mixtures, avoiding cross-interference. Therefore, the fabricated acetone gas sensor effectively reduces the excitation temperature and improves selectivity for acetone. Attached Figure Description

[0037] Figure 1 This is a schematic flowchart of a method for preparing an acetone gas sensor based on bimetallic loaded nanoparticles in one embodiment of the present invention.

[0038] Figure 2 This is a resistance-time curve of an acetone gas sensor based on bimetallic loaded nanoparticles in one embodiment of the present invention for acetone response testing.

[0039] Figure 3 This is a bar chart showing the gas sensitivity of an acetone gas sensor based on bimetallic loaded nanoparticles in one embodiment of the present invention. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0041] Please refer to Figure 1 This invention proposes a method for preparing an acetone gas sensor based on bimetallic loaded nanoparticles, the steps of which include:

[0042] S1. Add tin chloride to a solution containing a complexing agent and deionized water, stir at 60°C for 10 minutes, then add ammonia until the pH reaches 3. After centrifugation and washing, tin hydroxide precipitate powder is obtained.

[0043] In step S1, the complexing agent includes citric acid and ethylenediaminetetraacetic acid, and the tin chloride includes at least one of tin tetrachloride and tin dichloride.

[0044] Step S1 includes:

[0045] S1.1 Add a complexing agent to high-purity deionized water with a resistivity ≥18.2MΩ·cm, set the temperature to 60℃, and control the stirring speed at 400~600rpm.

[0046] Citric acid and ethylenediaminetetraacetic acid (EDTA) are both multidentate complexing agents that can form stable complexes with tin ions, reducing the free concentration of tin ions in water and thus slowing down their hydrolysis reaction. This complexing effect helps control the rate of nucleation and prevents excessively rapid precipitation that leads to uneven particle size.

[0047] At 60℃, the complexation reaction in the solution accelerates, which is beneficial for the complexing agent to fully combine with metal ions. A stirring rate of 400–600 rpm ensures uniform mixing of the solution, prevents excessively high local concentrations, and also promotes uniform temperature distribution. High-purity deionized water with a resistivity ≥18.2 MΩ·cm is used to ensure that there are no impurities in the solution that could interfere with the complexation reaction. According to the reaction design, equimolar amounts of citric acid and EDTA (the specific ratio is optimized through experiments) can be used to achieve the best complexation effect. A stable reaction system was constructed, the activity of tin ions was controlled, and their hydrolysis rate was slowed down, ensuring that the subsequent precipitation process was carried out under controlled conditions, thus laying the foundation for the preparation of a uniform and well-dispersed precipitate powder.

[0048] S1.2 Continue to add tin chloride, and keep the solution at 60°C with stirring for 10 minutes. While stirring continuously, titrate ammonia and surfactant until the solution pH reaches 3 to obtain a precipitate mixture. The surfactant includes at least one of sodium dodecyl sulfate and polyvinylpyrrolidone.

[0049] Tin tetrachloride or tin dichloride is selected, as it partially hydrolyzes in water. In the presence of a complexing agent, tin ions first form complexes with citric acid and EDTA, ensuring uniform dispersion in the solution. The purpose of titrating ammonia is to neutralize the solution and raise the pH, thereby inducing the hydrolysis of tin ions to form tin hydroxide precipitate. Controlling the pH to 3 is crucial; if the pH is too low, hydrolysis is insufficient, resulting in incomplete precipitation; if the pH is too high, hydrolysis is too rapid, easily leading to rapid growth and aggregation of precipitate particles. Due to the presence of the complexing agent, the precipitate formed is tin hydroxide under complexation regulation, which can be converted into tin dioxide by subsequent heat treatment. Controlling the pH to 3 ensures a moderate precipitation rate, which is conducive to the formation of small and uniform nuclei.

[0050] Adding surfactants such as sodium dodecyl sulfate (SDS) or polyvinylpyrrolidone (PVP) can coat the surface of nascent particles during precipitation, preventing direct contact and agglomeration between particles. This facilitates obtaining a precipitated powder with uniform particle size distribution and high specific surface area. The surfactant is used at a low concentration (e.g., 0.1–0.5 wt%) relative to the reactants; the specific amount needs to be adjusted experimentally. Controlled hydrolysis of tin ions was achieved, resulting in a uniform and well-dispersed mixture of tin hydroxide precipitates, providing an excellent microstructure for subsequent nanoparticle loading and sensing performance.

[0051] S1.3 Centrifuge the precipitate mixture at a speed of 5000-8000 rpm for 10-15 minutes. After centrifugation, wash the mixture and dry it at 60-80°C to obtain tin hydroxide precipitate powder.

[0052] Centrifugation at 5000–8000 rpm for 10–15 minutes effectively separates the precipitate from the mother liquor, removing most unreacted ions (such as ammonium chloride, residual complexing agents, and surfactants). Repeated washing with deionized water further removes impurities from the solution, ensuring precipitate purity. Drying at 60–80°C, avoiding excessively high temperatures to prevent over-sintering or grain growth, maintains high specific surface area and good dispersibility, providing an ideal substrate for subsequent heat treatment and bimetallic loading. Centrifugation and washing effectively remove impurities and byproducts, ensuring high purity of the precipitate powder. Controlling drying temperature and time helps maintain the stability of the precipitate's microstructure, preventing particle growth or agglomeration, ultimately yielding a high specific surface area, highly active tin hydroxide precipitate powder suitable for subsequent bimetallic loading steps. Using high-purity deionized water and precise temperature and stirring control ensures uniform mixing of ions and complexing agents in the reaction system, reducing impurity introduction and ensuring the reproducibility of the chemical reaction. The rapid hydrolysis of tin ions is mitigated by utilizing the dual complexation effect of citric acid and EDTA. Simultaneously, precise titration of ammonia to pH 3 ensures slow, controlled precipitation, resulting in uniformly sized and well-dispersed precipitate nuclei. The introduction of surfactants (SDS or PVP) during titration forms a protective layer on the particle surface, reducing adsorption and aggregation between particles, ultimately forming a precipitate powder with a high specific surface area, which is beneficial for subsequent catalytic activity enhancement. Efficient centrifugation, repeated washing, and low-temperature drying remove residual reactants and impurities while preserving the fine structure of the precipitate, providing an ideal precursor for subsequent heat treatment and functional activation.

[0053] S2. Tin hydroxide precipitate powder was added sequentially to indium trichloride tetrahydrate powder, gold chloride powder and platinum tetrachloride powder and ball-milled and mixed. The mixture was sintered at 600℃ for 2 hours to obtain bimetallic supported nanoparticles. The molar ratio of tin hydroxide precipitate powder: indium trichloride tetrahydrate powder: gold chloride powder: platinum tetrachloride powder = (40~60): (3~5): 1: 1.

[0054] Indium trichloride tetrahydrate is added during the S2 process, resulting in a tin / indium mixed crystal or heterojunction structure in the final product. This heterostructure optimizes carrier distribution and band structure, helping to improve the sensor's response to specific gases (such as acetone) while reducing the response to other volatile organic compounds. It improves the intrinsic electrochemical properties of the sensing material, providing an electronic basis for selective detection. The heterojunction structure can also modulate surface adsorption kinetics at certain temperatures, making the response difference between the target gas and other gases more pronounced.

[0055] Step S2 includes:

[0056] S2.1. Add tin hydroxide precipitate powder, indium trichloride tetrahydrate powder, gold chloride powder, and platinum tetrachloride powder to a ball mill in sequence, and add an inert solvent. The rotation speed is 400-500 rpm, and the ball milling time is 3-4 hours. During the ball milling process, inert gas is introduced and the ball milling mode is set to stop for 10 minutes every 1 hour. The inert solvent includes at least one of isopropanol, n-hexane, and toluene.

[0057] During ball milling, mechanical impact and shear force disperse the components, ensuring thorough mixing of the precursors of tin hydroxide, indium, gold, and platinum. The addition of an inert solvent reduces electrostatic adsorption between particles and the risk of localized overheating, thus maintaining particle fineness. The introduction of an inert gas (e.g., argon) prevents oxidation reactions during high-temperature ball milling, while intermittent milling reduces the overheating effect of continuous high-energy impacts, helping to control particle growth and prevent agglomeration. Pre-uniform dispersion of the components creates a favorable condition for the uniform loading of bimetallic nanoparticles onto the matrix during subsequent sintering. The micro-mixing state between the precursors during ball milling allows the reduction of gold and platinum to form fine and dispersed nanoparticles, exerting a synergistic catalytic effect. Thorough mixing of the components through mechanical force ensures a uniform multiphase material structure during subsequent sintering; the addition of an inert solvent and the use of intermittent ball milling effectively prevent excessive particle agglomeration, promoting the formation of precursor powders with high specific surface area; the introduction of an inert gas reduces the risk of oxidation and ensures the chemical stability of the mixed powder, providing a good foundation for bimetallic loading and subsequent catalytic efficiency.

[0058] S2.2 Set the heating rate to 5℃ / min, raise the temperature to 600℃, maintain this temperature for 2 hours, apply ultraviolet light treatment after heating, cool down to room temperature, and control the cooling rate to within 5℃ / min to obtain bimetallic supported nanoparticles.

[0059] At 600℃, the precursors undergo solid-state reactions. Tin hydroxide dehydrates during heat treatment, transforming into tin dioxide or related oxides, while indium trichloride tetrahydrate transforms into indium trioxide. These two may form mixed-crystal or heterojunction structures, which helps improve carrier transport. Gold chloride and platinum tetrachloride are reduced to gold and platinum nanoparticles at high temperatures, achieving uniform loading of the bimetallic compounds on the support surface through interfacial interactions with the oxide matrix. The synergistic effect of gold and platinum significantly reduces the activation energy of the reaction, enhancing the catalytic and gas-sensitive reaction rates. Heating and cooling rates are controlled within 5℃ / min to prevent excessively rapid grain growth or cracking caused by thermal stress, ensuring uniform crystal phase and structural stability. Applying ultraviolet light irradiation after sintering further modulates the surface state of the nanoparticles, such as improving the surface oxidation state, activating catalytic active sites, or removing surface organic residues. Ultraviolet light treatment helps excite the photothermal synergistic adaptive effect, enabling the sensor to achieve higher selectivity and sensitivity to acetone gas under low power consumption conditions. High-temperature sintering ensures solid-state reactions among all components, forming a uniform mixed-crystal / heterojunction structure, while bimetallic nanoparticles are uniformly loaded onto the matrix. Gold and platinum nanoparticles achieve synergistic catalysis after high-temperature reduction, significantly enhancing the catalytic activity and selectivity of the sensing material for acetone gas. UV post-treatment further optimizes the nanoparticle surface structure and activates active sites, facilitating rapid response and low detection limits in gas sensing. Temperature control and inert gas protection ensure controlled grain growth during sintering, resulting in a product with high purity and a stable microstructure, providing a solid foundation for subsequent device integration.

[0060] S3. Add ethylene glycol and zirconium oxide ball milling beads to the bimetallic loaded nanoparticles and ball mill for 8 hours to obtain a dispensing solution. Coat the dispensing solution onto a micro-motor heating plate, dry it at room temperature, and then sinter it at 200~400℃ for 3~4 hours to obtain an acetone gas sensor based on bimetallic loaded nanoparticles.

[0061] Bimetallic supported nanoparticles, obtained through fine ball milling and controlled sintering processes (S2 and S3), possess high specific surface area and fine, uniform particle size. This nanostructure provides numerous reactive sites for acetone gas, enabling more rapid adsorption and reaction of gas molecules at lower temperatures. The abundant exposed catalytic sites make the sensing layer more sensitive to the reaction of acetone molecules, shortening the response time, and achieving a high signal response even at low temperatures.

[0062] Step S3 includes:

[0063] S3.1, Select crystal orientation as <100> A 500μm thick p-type silicon wafer was ultrasonically cleaned sequentially with acetone, isopropanol, ethanol, and deionized water, and then dried with nitrogen to obtain a substrate.

[0064] Acetone, isopropanol, and ethanol, as organic solvents, can effectively dissolve surface oil, organic contaminants, and residues. Deionized water is used to remove water-soluble impurities. Nitrogen gas is used for drying to prevent water stains and secondary contamination. p-type refers to silicon wafers doped with acceptor impurities (such as boron), making their charge carriers primarily holes. p-type silicon wafers exhibit good conductivity and specific electronic properties during manufacturing, making them suitable for various types of semiconductor devices. <100> Oriented silicon wafers exhibit excellent crystal uniformity, which facilitates subsequent thin film deposition and etching. P-type doping provides the necessary electrical properties. High purity and a uniform surface ensure good adhesion and uniformity of subsequent layer deposition. <100> Silicon wafers exhibit better uniformity and controllability during chemical etching and thermal treatment, which helps to form stable micro-electromechanical systems (MEMS).

[0065] S3.2. A 1 μm thick support layer is deposited on the substrate by chemical vapor deposition. The support layer is exposed to ultraviolet light to obtain an image of the heating electrode. Then, a 200 nm thick heating electrode is deposited on the heating electrode image by magnetron sputtering.

[0066] The support layer includes at least one of silicon nitride, silicon dioxide, and aluminum oxide. Silicon nitride possesses excellent mechanical strength, thermal stability, and insulation properties; silicon dioxide is chemically stable and has a smooth surface; and aluminum oxide has high hardness and corrosion resistance. The heating electrode includes at least one of platinum, gold, and doped polycrystalline silicon, exhibiting high-temperature stability and excellent conductivity. Ultraviolet light exposure is used to pattern the photoresist, defining the geometric region of the heating electrode. Magnetron sputtering deposits the metal electrode, ensuring its thickness and uniformity. Ultraviolet light patterning ensures the precise definition and positioning of the heating electrode; uniform deposition of the heating electrode ensures rapid local heating, providing a stable temperature field and ensuring the sensing layer operates within its optimal temperature range.

[0067] Place the pre-cleaned and dried support substrate on a spin coater. Add an appropriate amount of positive (or negative) photoresist and start the spin coating program. Generally, set the spin speed to 3000–4000 rpm and the spin coating time to approximately 30–60 seconds to form a uniform film. After spin coating, pre-bake (soft bake) on a hot plate, for example, at 90°C for 60 seconds, to remove solvent and make the photoresist film more uniform and stable. Load the photoresist-coated substrate into the exposure machine. Align the pre-fabricated photomask, ensuring precise alignment of the pattern required for the heating electrodes.

[0068] Set the ultraviolet light exposure parameters (use ultraviolet light with a wavelength of 365nm). The exposure dose can be set to 100-200mJ / cm². Adjust the exposure time according to the photoresist requirements. After the exposure is completed, remove the substrate from the exposure machine.

[0069] The exposed substrate undergoes a post-bake (hard bake), for example, at 110°C for 60–90 seconds, to enhance the photoresist's resistance. The substrate is then immersed in a suitable developer (selecting a specific developer based on the photoresist type) for 30–60 seconds until the predetermined heating electrode pattern area is clearly visible. The substrate is rinsed with deionized water to remove developer residue and dried with nitrogen. The photoresist pattern is checked for compliance, ensuring sharp edges and no residue. Through UV exposure and development, a precise photoresist pattern can be formed on the support layer surface, defining the geometric area of ​​the heating electrode and providing a precisely defined template for subsequent metal deposition.

[0070] The substrate with the pre-patterned photoresist is fixed on the sample stage of the magnetron sputtering system. The deposition chamber is evacuated to prevent oxidation or impurity deposition. High-purity argon gas is backfilled to an appropriate operating pressure (e.g., 2–5 mTorr). The target material (e.g., platinum or gold) is selected as the deposition source, and the target material is mounted on the sputtering target holder. Depending on the target material and desired deposition rate, a direct current (DC) sputtering mode is generally used, with a power between 100 and 300 W. Depending on the deposition rate, for a target thickness of 200 nm, the deposition time is typically several minutes to tens of minutes. The substrate can be appropriately heated (e.g., 50–100 °C) to improve film adhesion and uniformity. Sputtering is initiated, and metal ions bombard and deposit onto the substrate in the vacuum. During deposition, the sample stage is rotated to ensure uniform deposition and consistent electrode thickness. After deposition, the sputtering machine is turned off, and the sample is removed from the deposition chamber after reaching room temperature. Magnetron sputtering deposition technology ensures high thickness uniformity and good adhesion of the metal electrodes, accurately replicating the pattern defined by the photoresist. This process enables the deposition of a metal layer at a lower temperature, which helps maintain the integrity of the underlying structure. At the same time, the deposited electrode has excellent conductivity and thermal stability, providing the sensor with efficient heating and signal acquisition functions.

[0071] S3.4. A 450 nm thick insulating layer is deposited on the heated electrode using plasma-enhanced chemical vapor deposition (PECVD). The insulating layer is then patterned using ultraviolet light to obtain a detection electrode image. A 200 nm thick detection electrode is then deposited on the detection electrode image using magnetron sputtering. The insulating layer includes at least one of silicon dioxide, silicon nitride, and polyimide, and the detection electrode includes at least one of platinum, gold, and palladium. A 450 nm thick insulating layer (optional materials: silicon dioxide, silicon nitride, or polyimide) is deposited on the heated electrode using PECVD, and then patterned using ultraviolet light to form a detection electrode image. Subsequently, a 200 nm thick detection electrode (optional materials: platinum, gold, or palladium) is deposited using magnetron sputtering. Good electrical isolation between the heated electrode and the detection electrode is ensured while maintaining thermal conductivity. For example, palladium has catalytic activity; platinum and gold are also commonly used to provide stable, low-noise detection signals. Ultraviolet light exposure and patterning are used to form a detection electrode pattern on the insulating layer, ensuring that the detection electrode is deposited only in designated areas. The insulating layer effectively isolates the heating and detection electrodes, preventing short circuits and ensuring stable device operation. Through patterning and magnetron sputtering, detection electrodes with uniform shape and stable thickness are formed, providing a reliable platform for sensor signal acquisition.

[0072] S3.5. Simultaneous etching of the insulating and support layers using inductively coupled plasma (ICP) etching exposes the heating electrodes. ICP etching is used to simultaneously etch the insulating and support layers to expose the heating electrode pads and predetermined areas. Fluorine- or chlorine-based gases are selected, and appropriate etching conditions are chosen based on the material. A patterned mask protects non-etched areas, removing material only in the required areas. This exposes the heating electrode pads and wet etching windows, providing a pathway for subsequent device assembly and silicon substrate release, laying the foundation for electrical connections and external packaging.

[0073] S3.6. The silicon substrate is etched using a potassium oxide solution, rinsed with deionized water, and dried with nitrogen to obtain a micro-motor heating plate. Wet etching of the silicon substrate with a potassium oxide solution, followed by rinsing with deionized water and drying with nitrogen, releases the cantilever beam structure, resulting in the micro-motor heating plate. Potassium oxide etching is used to release the MEMS structure. Parameters such as temperature and concentration control the etching rate and morphology. Successful removal of the silicon substrate allows the heating plate to exhibit a cantilever beam structure, providing an efficient and uniform heating area. By strictly controlling the etching conditions, a stable and durable micro-motor heating plate is obtained, ensuring the reliability of subsequent sensing tests.

[0074] The cantilever beam in a microelectromechanical (MEMS) heating plate is a microelectromechanical structure made of silicon, silicon nitride, or other semiconductor materials. Its main characteristic is that one end is fixed to the substrate while the other end is suspended freely, forming a cantilever-like structure. Due to its low heat capacity and short heat conduction path, the cantilever beam structure can achieve efficient localized heating while reducing energy consumption. The cantilever beam provides stable mechanical support for the heating element and sensing layer, allowing the sensor structure to be integrated into miniature devices. The low thermal mass facilitates rapid heating and cooling processes, thereby shortening the sensor's response and recovery time.

[0075] S3.7. Bimetallic-loaded nanoparticles are mixed with ethylene glycol, and then ball-milled with zirconia grinding beads at a speed of 400–500 rpm for 8 hours to obtain a dispensing solution. Ethylene glycol, as a polar dispersion medium, has a high boiling point and maintains stable dispersion at room temperature, contributing to the formation of a uniform ink. Zirconia grinding beads, as a high-hardness grinding medium, can further refine the powder particle size and prevent agglomeration through mechanical shearing. Inert solvents (such as isopropanol, n-hexane, and toluene) help reduce powder adhesion and electrostatic aggregation, ensuring uniform dispersion. Through prolonged ball milling and the assistance of suitable solvents, the bimetallic-loaded nanoparticles are uniformly dispersed in ethylene glycol, forming a stable dispensing solution. This reduces particle agglomeration, increases the specific surface area and activity of the subsequent sensing membrane, and enhances catalytic and gas-sensing effects.

[0076] In one embodiment, step S3.7 may be:

[0077] Bimetallic supported nanoparticles were added to ethylene glycol and stirred at 400 rpm for 5 minutes. Then, pyrrole monomer was added and stirring continued. The mass ratio of pyrrole monomer to bimetallic supported nanoparticles was (1~2):50. The ambient temperature was then lowered to 0~5℃ and an oxidant solution was added. The oxidant solvent included at least one of ferric chloride and ammonium persulfate. Finally, zirconia ball milling beads were added for ball milling at a speed of 400~500 rpm for 8 hours to obtain the dispensing solution.

[0078] The introduction of partially polymerized nanoscale polypyrrole, when combined with bimetallic-loaded nanoparticles, forms multi-level conductive channels, significantly improving the overall conductivity of the sensing layer and facilitating signal transmission and amplification. The presence of polypyrrole helps improve the electron density on the metal oxide surface, further stimulating the synergistic catalytic effect of the bimetals (gold and platinum), and enhancing the sensitivity and selectivity of the acetone gas reaction. Low-temperature partial polymerization combined with ultrasonic and ball-milling-assisted mixing ensures uniform dispersion of the nanoscale conductive polymer and the metal-loaded particles, preventing large particle agglomeration and thus improving the repeatability and stability of the sensor.

[0079] S3.8. The dispensing solution is uniformly deposited onto a micro-motor heating plate using inkjet printing or screen printing. After deposition, sintering is performed at 200℃~400℃ to obtain an acetone gas sensor based on bimetallic loaded nanoparticles. Inkjet / screen printing provides uniform and controllable film deposition, ensuring consistent sensing layer thickness. Sintering at 200℃~400℃ allows ethylene glycol to evaporate and promotes the bonding between nanoparticles and crystal phase optimization, while forming a robust sensing film. This ensures the formation of a continuous, crack-free film of bimetallic loaded nanoparticles, improving the consistency and sensitivity of gas sensing response. The sintering process promotes crystal phase transformation and interparticle bonding, improving the mechanical and chemical stability of the sensing layer and contributing to long-term stable operation.

[0080] Place the prepared micromotor heating plate on a clean bench, ensuring the surface is free of dust and oil. A light plasma cleaning treatment can be performed to improve surface wettability and adhesion. Ensure the dispensing solution can uniformly wet and adhere well to the substrate during inkjet printing. Stir the prepared dispensing solution thoroughly to ensure stable dispersion of the suspension. Filter the dispensing solution using a 0.45μm or finer filter to remove large particles or agglomerates and prevent nozzle clogging. Ensure the inkjet system operates smoothly to obtain a highly uniform film. Adjust the print resolution and print speed of the inkjet printer (e.g., inkjet dispensing machine), typically setting the print resolution to 300–600 dpi. Set the inkjet head operating temperature (generally at room temperature or slightly above, such as 30°C), and adjust the spacing and jet frequency to ensure uniform coverage between each nozzle. Perform pre-calibration and test prints on test samples to determine the optimal printing parameters. Ensure the dispensing solution is uniformly deposited on the surface of the micromotor heating plate to obtain a continuous and uniform sensing layer pattern. The prepared substrate is fixed on the printing platform, and the filtered dispensing solution is loaded. The printing program is started, and the dispensing solution is deposited according to the preset pattern. During the printing process, the environment (temperature and humidity) is kept stable to prevent the dispensing solution from drying or settling unevenly. A precise and uniform dispensing solution layer is deposited on the substrate, providing a foundation for the subsequent sintering to form the sensing layer. After inkjet printing, the sample is placed in a room temperature environment or dried in a low-temperature drying oven (e.g., 50°C, 30 minutes to 1 hour) to allow the ethylene glycol solvent to evaporate moderately, forming a pre-cured sensing film. The uniformity and defects of the dispensing solution layer are checked, and reprinting or localized repairs are performed as necessary. The dispensing solution film is ensured to be uniform and free of sagging, laying the foundation for subsequent high-temperature sintering.

[0081] Select a suitable mesh size (e.g., 200-300 mesh) to ensure the screen meets the required graphic resolution for the sensing layer. Clean and tension the screen to ensure it is flat and wrinkle-free. Obtain a uniform and stable screen to provide a foundation for subsequent pattern transfer. Evenly coat the photosensitive emulsion onto the screen (using a squeegee or dip-coating method), controlling the emulsion thickness appropriately. Place the coated screen in an exposure machine and expose it to ultraviolet light using a pre-designed patterned photomask. After exposure, perform development to wash away uncured photosensitive emulsion, forming a patterned screen printing plate. Obtain open areas on the screen printing plate for the area requiring the sensing layer graphic, ensuring that the dispensing solution only deposits onto the substrate through these open areas during printing. Similar to inkjet printing, pre-treat the micro-motor heating plate to ensure surface cleanliness and good adhesion. Improve the adhesion of the dispensing solution to ensure clear printed graphics. Adjust the viscosity of the dispensing solution to a suitable level for screen printing, adding an appropriate amount of thinner (e.g., isopropanol) if necessary to adjust the flowability. Filter the dispensing solution (e.g., using a 0.45μm filter) to ensure no large particles clog the screen. This ensures the dispensing solution has good flowability and adhesion, facilitating uniform transfer through the screen. Fix the printing plate on the screen printing machine and place the pre-treated substrate on the printing table. Pour the prepared dispensing solution onto the screen printing plate and use a squeegee to scrape it from one side at an appropriate angle and with uniform pressure, pushing the dispensing solution through the open area onto the substrate. Repeat as necessary to ensure complete coverage of the sensing layer pattern. Accurately and uniformly transfer the dispensing solution onto the substrate to form a continuous sensing film. Place the printed substrate in a drying oven and dry at an appropriate temperature (e.g., 50–60°C) for 30 minutes to 1 hour to allow the dispensing solution to fully cure. Check the uniformity and integrity of the printed layer to ensure no peeling or unevenness. Ensure the dispensing solution cures stably to provide a high-quality sensing layer for subsequent sintering and activation processes.

[0082] Following step S3.8, the following is also included:

[0083] S3.9 Immerse the acetone gas sensor based on bimetallic loaded nanoparticles in a solution containing functional organic molecules. The immersion time is controlled between 30 minutes and 1 hour, allowing the functional organic molecules to spontaneously adsorb and form a dense monolayer. After removal, rinse with deionized water and dry with nitrogen. The monolayer can construct a molecular-level modification layer on the sensor surface, and the functional groups can form specific interactions with acetone molecules, thereby improving the sensor's selectivity for acetone. This enables chemical recognition and regulation at the molecular level, further reducing interference from other volatile organic compounds.

[0084] The solvent for the functional organic molecule may be at least one of the following: an ethanol solution containing octylthiol, an isopropanol solution containing 3-mercaptopropyltrimethoxysilane, or a hexane solution containing 11-mercaptoundecanoic acid.

[0085] S3.10. In an air environment, heat the acetone gas sensor based on bimetallic loaded nanoparticles to 500℃, maintain it for 10 minutes, cool it to room temperature, and then irradiate it with ultraviolet light with a wavelength of 365nm or blue light with a wavelength of 450nm. The light intensity is controlled between 10 and 15mW / cm², and the irradiation treatment is continued for 20 minutes.

[0086] Short-term activation at 500℃ helps to further improve the crystal phase of nanoparticles, remove organic residues, and promote the formation of a stable synergistic structure at the metal-oxide interface. Using a 365nm or 450nm wavelength light source, photoexcitation alters the oxidation state and carrier distribution on the surface of bimetallic nanoparticles, stimulating a photothermal synergistic adaptive effect and optimizing catalytic activity. A moderate intensity of 10–15 mW / cm² and an irradiation time of 20 minutes ensure sufficient activation of surface active sites without causing excessive thermal effects or material damage. The combination of high-temperature activation and subsequent photo-irradiation post-treatment not only makes the crystal phase of the sensing layer more uniform and stable but also activates the active sites on the surface of the bimetallic nanoparticles. After UV / blue light treatment, the catalytic reaction rate and selectivity of the sensing layer for acetone gas are significantly improved, while achieving low-power operation to meet practical application requirements.

[0087] S3.11. A hydrophobic self-healing polymer solution is uniformly deposited on the surface of the sensing layer using a spin coating method. The spin coating conditions are a spin speed of 3000 rpm and a spin coating time of 30 seconds; then, the film is baked at 50°C for 5-10 minutes to cure. This ensures that the coating can isolate environmental humidity interference while maintaining a certain degree of permeability to acetone gas. The hydrophobic self-healing polymer solution includes a polymer matrix and modifying groups. The polymer matrix includes at least one of polydimethylsiloxane solution, polyvinylidene fluoride solution, and fluorinated polypropylene solution. The modifying groups include at least one of 3-mercaptopropyltrimethoxysilane, silane containing pyridine groups, and 2-uridine-4[1H]-pyrimidinone modified monomers.

[0088] The hydrophobic polymer matrix has low surface energy, effectively blocking water molecules from entering the sensing layer and reducing the interference of environmental humidity fluctuations on the sensor baseline and response. The ultrathin and uniform spin-coated film can isolate moisture while allowing target gas (acetone) molecules to diffuse rapidly to the sensitive layer, thus ensuring the high sensitivity of the sensor. Modified groups (such as 3-mercaptopropyltrimethoxysilane, silanes containing pyridine groups, or 2-uridine-4[1H]-pyrimidinone modified monomers) can achieve self-healing and restore the integrity of the film when the film is micro-damaged through reversible bonding (such as dynamic sulfur bonds, reversible metal coordination, or hydrogen bonds). The self-healing function can automatically repair microcracks and defects during long-term use, maintain the stable response characteristics of the sensor, and reduce the frequency of maintenance and replacement. Spin coating can form an ultrathin, uniform, and dense protective film on the surface of the sensing layer without significantly hindering the diffusion of acetone gas, while improving the adhesion between the film and the underlying sensing material. It effectively isolates interference from external humidity and impurities, improving the signal stability and repeatability of the sensor, thereby achieving more accurate acetone concentration detection. Baking and curing at 50℃ is a low-temperature and simple process, avoiding potential thermal damage to the sensing layer from high temperatures, while also reducing energy consumption, making it suitable for the fabrication of portable sensors.

[0089] When sensors are subjected to external impacts, bending, or vibration during use, microcracks or defects may form in localized areas. Introducing modified groups into the polymer addresses this issue. These groups, after breaking at the crack, will recombine under localized temperature changes or slight external heating (e.g., a slight increase in ambient temperature to 60°C), closing the crack and restoring the material structure to its integrity. In practical applications, even if microcracks appear on the sensor surface, the self-healing process can restore the continuity and function of the sensing layer, reducing performance degradation caused by mechanical fatigue. Long-term exposure to high humidity environments or environments containing trace amounts of corrosive gases can lead to surface degradation or microcracks due to moisture or chemical corrosion. By introducing self-healing modified groups into the polymer, these groups, after being damaged by humidity or chemical action, will spontaneously recombine under environmental conditions (e.g., room temperature or slightly higher temperatures), repairing the damaged areas. This mechanism forms a self-healing protective layer on the sensor surface, mitigating long-term performance drift caused by environmental humidity or corrosion, and maintaining the sensor's high sensitivity and stability. In practical applications, sensors may be subjected to localized temperature fluctuations or changes in light intensity. When modified functional groups are used in the design, these groups respond to temperature and light. For example, when the sensing layer is locally heated or irradiated with ultraviolet / blue light, broken dynamic bonds can rapidly reform under the stimulation conditions; in addition, photoexcitation can induce the rearrangement of active sites on the material surface, which can indirectly accelerate the self-healing process. This self-repair mechanism can be artificially triggered under predetermined activation conditions (e.g., irradiation with ultraviolet and infrared light), enabling the sensor to self-repair before detection or during periodic maintenance, ensuring the long-term consistency and stability of device performance.

[0090] This invention proposes an acetone gas sensor based on bimetallic loaded nanoparticles, which is fabricated using a method for preparing such a sensor. The bimetallic loaded nanoparticle-based acetone gas sensor includes tin hydroxide precipitated powder, indium trichloride tetrahydrate powder, gold chloride powder, platinum tetrachloride powder, and a micro-motor heating plate; wherein,

[0091] Tin hydroxide precipitate powder is used as a gas-sensitive material in acetone gas sensors;

[0092] Indium trichloride tetrahydrate powder is used to improve the sensitivity and selectivity of acetone gas sensors to acetone gas;

[0093] Gold chloride powder promotes the adsorption and reaction of acetone molecules on the surface of the acetone gas sensor;

[0094] Platinum tetrachloride powder is used in synergistic catalysis with gold chloride powder to reduce the activation energy of the reaction;

[0095] The micro-motor heating plate is used to ensure that the acetone gas sensor is maintained within the optimal temperature range during operation.

[0096] The metal oxides used in the sensor adsorb oxygen molecules from the air on their surface at high temperatures, forming reactive oxygen ions. When acetone gas molecules come into contact with the surface of the sensing material, they react with the adsorbed oxygen ions to produce carbon dioxide and water, while releasing electrons back into the metal oxide, causing a significant change in the material's conductivity. This change in resistance is the basis for the sensor's detection of acetone concentration. Metal nanoparticles (such as gold and platinum) are loaded into the sensing material; these act as catalysts at high temperatures, accelerating the reaction between acetone and adsorbed oxygen ions. The synergistic effect between gold and platinum lowers the activation energy of the reaction, enhancing the reaction rate of acetone gas molecules, thereby improving the sensor's sensitivity and selectivity to low concentrations of acetone.

[0097] Micro-motor heating plates enable efficient localized heating, maintaining the sensing material at its optimal operating temperature (e.g., 200–400°C) to stimulate the best gas-sensitive response. Suitable temperatures not only ensure the gas reaction rate but also stabilize carrier concentration and surface reaction kinetics, thereby enabling the sensor to exhibit rapid response and high repeatability.

[0098] Figure 2 The resistance-time curve for acetone response testing shows that when 100 ppm acetone is continuously pulsed through the sensor, the resistance rises and falls rapidly and significantly, indicating high sensitivity to acetone and a fast response / recovery speed. The similar curve shapes from multiple pulse tests indicate good repeatability and signal stability.

[0099] Figure 3 The bar chart shows a comparison of the sensitivity to different gases (such as methane, ethanol, carbon monoxide, etc.). It can be seen that the sensitivity bar for acetone is significantly higher than that for other interfering gases, indicating that the sensor has significant selectivity for acetone.

[0100] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for fabricating an acetone gas sensor based on bimetallic loaded nanoparticles, characterized in that the steps include... include: S1. Add tin chloride to a solution containing a complexing agent and deionized water, stir at 60°C for 10 minutes, then add ammonia until the pH reaches 3, centrifuge and wash to obtain tin hydroxide precipitate powder. S2. Tin hydroxide precipitate powder is added sequentially to indium trichloride tetrahydrate powder, gold chloride powder and platinum tetrachloride powder and ball-milled and mixed. The mixture is then sintered at 600℃ for 2 hours to obtain bimetallic supported nanoparticles. The molar ratio is calculated as follows: tin hydroxide precipitate powder : indium trichloride tetrahydrate powder : gold chloride powder : platinum tetrachloride powder = (40~60) : (3~5) : 1 :

1. S3. Ethylene glycol and zirconium oxide ball milling beads are added to the bimetallic loaded nanoparticles and ball milled for 8 hours to obtain a dispensing solution. The dispensing solution is coated on a micro motor heating plate, dried at room temperature, and then sintered at 200~400℃ for 3~4 hours to obtain an acetone gas sensor based on bimetallic loaded nanoparticles. Step S3 includes: S3.1, Select crystal orientation as <100> A 500μm thick p-type silicon wafer was ultrasonically cleaned sequentially with acetone, isopropanol, ethanol, and deionized water, and then dried with nitrogen to obtain a substrate. S3.

2. A 1 μm thick support layer is deposited on the substrate by chemical vapor deposition, and the support layer is exposed to ultraviolet light to obtain a heating electrode image. Then, a 200 nm thick heating electrode is deposited on the heating electrode image by magnetron sputtering. S3.

4. An insulating layer with a thickness of 450 nm is deposited on the heating electrode by plasma-enhanced chemical vapor deposition. The insulating layer is exposed to ultraviolet light to obtain an image of the detection electrode. Then, a detection electrode with a thickness of 200 nm is deposited on the detection electrode image by magnetron sputtering. S3.

5. The insulating layer and the support layer are simultaneously etched by inductively coupled plasma etching to expose the heating electrode; S3.

6. The silicon substrate is etched using potassium hydroxide solution, cleaned with deionized water, and dried with nitrogen to obtain a micro-motor heating plate. S3.7 Add bimetallic loaded nanoparticles to ethylene glycol and stir at 400 rpm for 5 minutes. Then add pyrrole monomer and continue stirring. The mass ratio of pyrrole monomer to bimetallic loaded nanoparticles is (1~2):

50. Then lower the ambient temperature to 0~5℃ and add an oxidant solution. The oxidant solvent includes at least one of ferric chloride and ammonium persulfate. Finally, add zirconia ball milling beads and ball mill at 400~500 rpm for 8 hours to obtain the dispensing solution. S3.8 The dispensing solution is uniformly deposited on the micro-motor heating plate by inkjet printing or screen printing. After deposition, it is sintered at 200℃~400℃ to obtain an acetone gas sensor based on bimetallic loaded nanoparticles.

2. The method for preparing an acetone gas sensor based on bimetallic supported nanoparticles according to claim 1, characterized in that, In step S1, the complexing agent includes citric acid and ethylenediaminetetraacetic acid, and the tin chloride includes at least one of tin tetrachloride and tin dichloride.

3. A method for preparing an acetone gas sensor based on bimetallic supported nanoparticles according to claim 1 or 2, characterized in that, Step S1 includes: S1.1 Add a complexing agent to high-purity deionized water with a resistivity ≥18.2MΩ·cm, set the temperature to 60℃, and control the stirring speed at 400~600rpm; S1.2 Continue to add tin chloride, and keep the solution at 60°C while stirring for 10 minutes. While stirring continuously, titrate ammonia and surfactant until the solution pH reaches 3 to obtain a precipitate mixture. The surfactant includes at least one of sodium dodecyl sulfate and polyvinylpyrrolidone. S1.

3. The precipitate mixture is centrifuged at a speed of 5000-8000 rpm for 10-15 minutes. After centrifugation, it is washed and dried at 60-80°C to obtain tin hydroxide precipitate powder.

4. The method for preparing an acetone gas sensor based on bimetallic supported nanoparticles according to claim 1, characterized in that, Step S2 includes: S2.1 Add tin hydroxide precipitate powder, indium trichloride tetrahydrate powder, gold chloride powder and platinum tetrachloride powder to the ball mill in sequence, and add inert solvent. The speed is 400-500 rpm, the ball milling time is 3-4 hours, and inert gas is introduced during the ball milling process and the intermittent ball milling mode is set to stop for 10 minutes every 1 hour. S2.2 Set the heating rate to 5℃ / min, raise the temperature to 600℃, maintain this temperature for 2 hours, apply ultraviolet light treatment after heating, cool down to room temperature, and control the cooling rate to within 5℃ / min to obtain bimetallic supported nanoparticles.

5. The method for preparing an acetone gas sensor based on bimetallic supported nanoparticles according to claim 4, characterized in that, In step S2.1, the inert solvent includes at least one of isopropanol, n-hexane, and toluene.

6. The method for preparing an acetone gas sensor based on bimetallic loaded nanoparticles according to claim 1, characterized in that, Following step S3.8, the following is also included: S3.

9. In an air environment, heat the acetone gas sensor based on bimetallic loaded nanoparticles to 500°C, maintain it for 10 minutes, cool it to room temperature, and then irradiate it with ultraviolet light with a wavelength of 365nm or blue light with a wavelength of 450nm. The light intensity is controlled between 10 and 15mW / cm², and the irradiation treatment is continued for 20 minutes.

7. The method for preparing an acetone gas sensor based on bimetallic supported nanoparticles according to claim 1, characterized in that, The support layer includes at least one of silicon nitride, silicon dioxide, and aluminum oxide; the insulating layer includes at least one of silicon dioxide, silicon nitride, and polyimide; the heating electrode includes at least one of platinum, gold, and doped polycrystalline silicon; and the detection electrode includes at least one of platinum, gold, and palladium.

8. An acetone gas sensor based on bimetallic loaded nanoparticles, characterized in that, The acetone gas sensor is fabricated using a method according to any one of claims 1-7, wherein the acetone gas sensor based on bimetallic loaded nanoparticles comprises tin hydroxide precipitate powder, indium trichloride tetrahydrate powder, gold chloride powder, platinum tetrachloride powder, and a micro-motor heating plate; wherein, The tin hydroxide precipitate powder is used as a gas-sensitive material for an acetone gas sensor. The indium trichloride tetrahydrate powder is used to improve the sensitivity and selectivity of the acetone gas sensor to acetone gas; The gold chloride powder promotes the adsorption and reaction of acetone molecules on the surface of the acetone gas sensor; The platinum tetrachloride powder is used to synergistically catalyze the gold chloride powder to reduce the reaction activation energy; The micro-motor heating plate is used to ensure that the acetone gas sensor is maintained within the optimal temperature range during operation.

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