Acetone gas sensor sensitive materials, acetone gas sensors and detection methods

Abstract

This invention relates to a sensitive material for an acetone gas sensor, an acetone gas sensor, and a detection method. The preparation method of the sensitive material for the acetone gas sensor includes: weighing tin chloride hydrate and zinc acetate and dissolving them in deionized water to obtain a mixed solution; weighing lithium hydroxide and dissolving it in the mixed solution to obtain a reactant solution; stirring the reactant solution at a preset temperature for a preset time to allow the tin chloride hydrate, zinc acetate, and lithium hydroxide to react and obtain a reaction product; purifying and drying the reaction product sequentially; and calcining the dried reaction product to obtain a sensitive material. The sensitive material is SnO2 / Zn2SnO4, and has a cubic morphology with the (100) facet exposed, or an octahedral morphology with the (111) facet exposed. The gas sensor using the sensitive material prepared by this method exhibits good selectivity for acetone.

Description

Technical Field

[0001] This invention belongs to the field of micro-nano sensor technology, specifically relating to an acetone gas sensor sensitive material, an acetone gas sensor, and a detection method. Background Technology

[0002] In recent years, semiconductor-based gas sensors have received widespread attention for monitoring human health. Human exhaled air consists of a large amount of water vapor, various small-molecule inorganic gases, and a wide variety of volatile organic compounds in low concentrations. More than 30 of these gases have been identified as biomarkers for specific diseases and metabolic disorders. Acetone is one of the most abundant gases in human respiration and is an important product of lipid metabolism, serving as a gaseous biomarker for diabetes diagnosis. Diabetic patients experience glucose metabolism disorders due to insulin deficiency or ineffectiveness, leading to a predominance of lipid metabolism. Some studies have shown that the average acetone concentration in the breath of type 1 diabetic patients is significantly higher than in healthy individuals. In conclusion, detecting the concentration of acetone in exhaled breath allows for non-invasive and painless detection of diabetes, offering advantages such as convenience, speed, and cost-effectiveness. Therefore, non-invasive diabetes analysis technology based on respiratory acetone detection has great potential for clinical application.

[0003] Currently, gas chromatography-mass spectrometry (GC-MS) is a commonly used method in breathalyzer testing. Chromatography separates mixtures based on differences in physical properties such as boiling point, polarity, and adsorption, while gas chromatography uses a gas as the mobile phase. After the sample enters the chromatographic column with the carrier gas, the components in the sample, due to their different properties, establish adsorption and partition equilibration between the stationary phase and the carrier gas. Because of the different forces acting on the stationary phase, the components in the sample move at different speeds within the column and are gradually separated, eventually eluting from the stationary phase at different times. Mass spectrometry analyzes the sample by determining the mass-to-charge ratio of the ions in the sample. The process involves first ionizing the analytes using various ionization methods such as electron bombardment, laser ionization, field separation, or chemical ionization. Then, the interaction of electric and magnetic fields causes the ions to move at different speeds and deflect at different angles, resulting in separation according to their mass-to-charge ratio, thus generating a mass spectrum. The mass spectrometric information allows for qualitative and quantitative analysis of the sample.

[0004] Laser absorption spectroscopy is a highly sensitive and selective gas analysis technique. The main laser absorption spectroscopy methods used in breathalyzer tests include Tunable Semiconductor Laser Absorption Spectroscopy (TDLAS) and Cavity Ring-Off Method (CRDS). TDLAS combines laser modulation and spectral absorption to measure gas concentration. It adjusts the wavelength of the semiconductor laser according to the type of gas being measured and scans within a specific range to ensure the laser wavelength covers the gas absorption spectrum without interference from other gases, thus achieving the measurement of trace gases. CRDS couples the laser into a cavity composed of two mirrors with a reflectivity of over 99.9%, increasing the absorption path length through back-and-forth oscillation.

[0005] While gas chromatography-mass spectrometry and laser absorption spectroscopy offer good selectivity, their high cost, large size, and difficulty in integrating them into mobile devices make them unsuitable for developing portable respiratory diagnostic instruments. Summary of the Invention

[0006] To address the aforementioned problems in the prior art, this invention provides a sensitive material for an acetone gas sensor, an acetone gas sensor, and a detection method. The technical problem to be solved by this invention is achieved through the following technical solution:

[0007] The first embodiment of the present invention provides a method for preparing a sensitive material for an acetone gas sensor, comprising the following steps:

[0008] S1. Weigh out tin chloride hydrate and zinc acetate and disperse and dissolve them in deionized water to obtain a mixed solution;

[0009] S2. Weigh out lithium hydroxide and dissolve it in the mixed solution to obtain a reactant solution;

[0010] S3. Stir the reactant solution at a preset temperature for a preset time to allow the tin chloride hydrate, zinc acetate, and lithium hydroxide to react and obtain the reaction product;

[0011] S4. The reaction products are purified and dried sequentially.

[0012] S5. The dried reaction product is calcined to obtain a sensitive material, wherein the sensitive material is SnO2 / Zn2SnO4, the sensitive material has a cubic morphology, and the exposed crystal face of the cubic morphology is (100) face, or the sensitive material has an octahedral morphology, and the exposed crystal face of the octahedral morphology is (111) face.

[0013] In one embodiment of the present invention, the mass of the tin chloride hydrate is 0.7g, the mass of the zinc acetate is 0.439g, the volume of the deionized water is 60ml, the mass of the lithium hydroxide is 0.192g, the preset temperature is 85℃, the preset time is 6h, and the sensitive material has the cubic morphology.

[0014] In one embodiment of the present invention, the mass of the tin chloride hydrate is 0.7 g, the mass of the zinc acetate is 0.439 g, the volume of the deionized water is 60 ml, the mass of the lithium hydroxide is 0.528 g, the preset temperature is 85 °C, the preset time is 6 h, and the sensitive material has the octahedral morphology.

[0015] In one embodiment of the present invention, step S4 includes:

[0016] The reaction product was washed three times with deionized water and ethanol alternately to remove impurities and obtain a purified reaction product.

[0017] The purified reaction product was dried in a vacuum drying oven at a temperature of 60°C.

[0018] In one embodiment of the present invention, step S5 includes:

[0019] The dried reaction product was placed in a muffle furnace and heated to 600°C at a heating rate of 2°C / min. The product was then calcined at 600°C for 2 hours. After calcination, the sensitive material was obtained.

[0020] The second embodiment of the present invention provides an acetone gas sensor sensitive material, which is prepared by the preparation method described in the above embodiments, and the sensitive material is SnO2 / Zn2SnO4;

[0021] The sensitive material has a cubic morphology, and the exposed crystal face of the cubic morphology is the (100) face; or, the sensitive material has an octahedral morphology, and the exposed crystal face of the octahedral morphology is the (111) face.

[0022] A third embodiment of the present invention provides a method for manufacturing an acetone gas sensor, comprising the following steps:

[0023] S1. Disperse the sensitive material sample powder in deionized water and stir it into a paste. Apply the paste to the surface of the alumina ceramic tube and then calcine the coated alumina ceramic tube. The sensitive material sample powder is the acetone gas sensor sensitive material described in the above embodiment.

[0024] S2. A heating wire is passed through the calcined alumina ceramic tube. The calcined alumina ceramic tube is welded to a hexagonal base through the heating wires fixed at both ends and the through heating wire. Current is passed through the tube for aging to obtain a stable acetone gas sensor.

[0025] A fourth embodiment of the present invention provides an acetone gas sensor, manufactured by the method described in the above embodiments, comprising: a hexagonal base, a heating wire, and an alumina ceramic tube, wherein...

[0026] The surface of the alumina ceramic tube is coated with an acetone gas sensor sensitive material, and a heating wire runs through the alumina ceramic tube. Heating wires are fixed at both ends of the alumina ceramic tube.

[0027] The alumina ceramic tube is welded to a hexagonal base by heating wires fixed at both ends and through which heating wires pass.

[0028] The fifth embodiment of the present invention provides a detection method for an acetone gas sensor, comprising the following steps:

[0029] S1. The operating temperature of the sensor is controlled by controlling the temperature of the heating wire inside the alumina ceramic tube;

[0030] S2. At different operating temperatures, obtain the first stable resistance of the sensor in air and the second stable resistance in acetone, and use the first stable resistance and the second stable resistance to calculate the response value of the sensor to acetone.

[0031] S3. Determine the target operating temperature of the sensor based on the sensor's response to acetone at different operating temperatures;

[0032] S4. At the target operating temperature, test the acetone gas using the sensor.

[0033] In one embodiment of the present invention, the target operating temperature is 250°C.

[0034] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0035] This invention involves reacting tin chloride hydrate, zinc acetate, and lithium hydroxide, followed by calcination, to obtain a SnO2 / Zn2SnO4 sensitive material. The sensitive material has a cubic or octahedral morphology, with the exposed crystal face of the cubic morphology being the (100) face and the exposed crystal face of the octahedral morphology being the (111) face. Both the cubic and octahedral morphologies exhibit good response values ​​to acetone. Gas sensors prepared using this gas-sensitive material demonstrate good selectivity for acetone, with advantages such as a low detection limit, high sensitivity, low cost, small size, and simple operation. They are easy to integrate into mobile devices and are therefore suitable for the development of portable respiratory diagnostic instruments. Attached Figure Description

[0036] Figure 1 This is a schematic flowchart illustrating a method for preparing a sensitive material for an acetone gas sensor according to an embodiment of the present invention.

[0037] Figures 2a-2b Scanning electron microscope image of the SnO2 / Zn2SnO4 sensitive material prepared according to an embodiment of the present invention;

[0038] Figure 3 X-ray diffraction pattern of the zinc stannate sensitive material prepared according to the embodiments of the present invention;

[0039] Figure 4 This is a schematic diagram of the structure of an acetone gas sensor provided in an embodiment of the present invention;

[0040] Figure 5 The sensor provided in this embodiment of the invention provides a curve showing the change in response value of the sensor to 100 ppm acetone as a function of operating temperature;

[0041] Figure 6 The response recovery time curve of the sensor provided in this embodiment of the invention to acetone at 250°C is shown.

[0042] Figure 7 The response curves of the sensor provided in this embodiment of the invention to different concentrations of acetone are shown.

[0043] Figure 8 A bar chart showing the response values ​​of the sensor provided in this embodiment of the invention to different types of detected gases;

[0044] Figure 9 The sensor provided in this embodiment of the invention provides a five-cycle test curve of acetone.

[0045] Figure 10 This is a sensor stability test diagram provided for an embodiment of the present invention. It is used to evaluate the stability of the device. Detailed Implementation

[0046] The present invention will be further described in detail below with reference to specific embodiments, but the implementation of the present invention is not limited thereto.

[0047] Example 1

[0048] This embodiment provides a sensitive material for an acetone gas sensor and its preparation method. Please refer to [link to documentation]. Figure 1 , Figure 1 This is a schematic flowchart illustrating a method for preparing a sensitive material for an acetone gas sensor according to an embodiment of the present invention.

[0049] This embodiment uses a water bath method to prepare the sensitive material for an acetone gas detection sensor, specifically including the following steps:

[0050] S1. Weigh out tin chloride hydrate SnCl4·5H2O and zinc acetate C4H 10 OZn was dispersed and dissolved in deionized water to obtain a mixed solution.

[0051] S2. Weigh out lithium hydroxide (LiOH) and dissolve it in the mixed solution to obtain a reactant solution.

[0052] S3. Stir the reactant solution at a preset temperature for a preset time to allow the tin chloride hydrate, zinc acetate, and lithium hydroxide to react and obtain the reaction product.

[0053] S4. The reaction products are purified and dried sequentially.

[0054] S5. The dried reaction product is calcined to obtain a sensitive material, wherein the sensitive material is SnO2 / Zn2SnO4, the sensitive material has a cubic morphology, and the exposed crystal face of the cubic morphology is (100) face, or the sensitive material has an octahedral morphology, and the exposed crystal face of the octahedral morphology is (111) face.

[0055] In step S3, the reaction process of tin chloride hydrate, zinc acetate, and lithium hydroxide is as follows:

[0056] Zn 2+ +Sn 4+ +6OH - →ZnSn(OH)6

[0057] In step S5, zinc stannate undergoes a phase transition during calcination, and its chemical formula is:

[0058] ZnSn(OH)6 → ZnSnO3 + 3H2O

[0059] 2ZnSnO3→Zn2SnO4+SnO2

[0060] The sensitive material prepared by the above preparation method is a metal semiconductor oxide SnO2 / Zn2SnO4 (tin dioxide / zinc stannate), which has a cubic or octahedral morphology. The exposed crystal face of the cubic morphology is the (100) face, and the exposed crystal face of the octahedral morphology is the (111) face.

[0061] It should be noted that the purpose of the preparation method in this embodiment is to prepare SnO2 / Zn2SnO4 with a cubic or octahedral morphology. The specific preparation conditions can be set according to actual needs.

[0062] In one specific embodiment, the sensitive material has a cubic morphology and the exposed crystal face is the (100) face. The specific preparation process is as follows:

[0063] S1. Weigh out 0.7g SnCl4·5H2O (tin chloride hydrate) and 0.439g C4H 10 OZn (zinc acetate) was dispersed in 60 mL of deionized water and stirred at room temperature until fully dissolved to obtain a mixed solution;

[0064] S2. Weigh 0.192g of LiOH and add it to the above mixed solution, stirring continuously until dissolved;

[0065] S3. Heat the mixed solution to 85℃ and stir in a beaker for 6 hours to allow SnCl4·5H2O and C4H2O to react. 10 The reaction of OZn and LiOH yields the reaction product;

[0066] S4. After the solution has completely reacted, wash the reaction product three times with deionized water and ethanol alternately to remove impurities and obtain the purified reaction product; then dry the purified reaction product in a vacuum drying oven at 60°C for 12 hours.

[0067] S5. Place the dried reaction product in a muffle furnace and heat it to 600°C at a heating rate of 2°C / min. Calcine it at 600°C for 2 hours. After calcination, the sensitive material is obtained and labeled as S1.

[0068] In one specific embodiment, the sensitive material has an octahedral morphology and the exposed crystal face is the (111) face. The specific preparation process is as follows:

[0069] S1. Weigh out 0.7g SnCl4·5H2O (tin chloride hydrate) and 0.439g C4H 10 OZn (zinc acetate) was dispersed in 60 mL of deionized water and stirred at room temperature until fully dissolved to obtain a mixed solution;

[0070] S2. Weigh 0.528g of LiOH and add it to the above mixed solution, stirring continuously until dissolved;

[0071] S3. Heat the mixed solution to 85℃ and stir in a beaker for 6 hours to allow SnCl4·5H2O and C4H2O to react. 10 The reaction of OZn and LiOH yields the reaction product;

[0072] S4. After the solution has completely reacted, wash the reaction product three times with deionized water and ethanol alternately to remove impurities and obtain the purified reaction product; then dry the purified reaction product in a vacuum drying oven at 60°C for 12 hours.

[0073] S5. Place the dried reaction product in a muffle furnace and heat it to 600°C at a heating rate of 2°C / min. Calcine it at 600°C for 2 hours. After calcination, the sensitive material is obtained and labeled as S2.

[0074] Please see Figures 2a-2b , Figures 2a-2b This is a scanning electron microscope image of the SnO2 / Zn2SnO4 sensitive material prepared according to an embodiment of the present invention. Figure 2a Representative sample S1, Figure 2b The representative sample is S2. As can be seen from the scanning electron microscope image, the morphology of sample S1 is a cube with the (100) facet as the main exposed crystal facet, while the morphology of sample S2 is an octahedron with the (111) facet as the main exposed crystal facet.

[0075] Please see Figure 3 , Figure 3 The X-ray diffraction pattern of the zinc stannate sensitive material prepared according to the embodiments of the present invention is shown, where ZTO-Cube represents sample S1 and ZTO-Octahedron represents sample S2. The spectrum shows that the peak positions of the samples basically match those of the standard zinc stannate card (PDF: 24-1470), with the leftmost peak corresponding to the tin dioxide standard card (PDF: 1-625). This is because zinc stannate undergoes a phase transition during calcination, corresponding to the chemical formula: 2ZnSnO3=Zn2SnO4+SnO2.

[0076] In this embodiment, tin chloride hydrate, zinc acetate and lithium hydroxide are reacted and then calcined to obtain SnO2 / Zn2SnO4 sensitive material. The sensitive material has a cubic morphology with the (100) facet exposed, or the sensitive material has an octahedral morphology with the (111) facet exposed. Both the cubic and octahedral morphologies have good response values ​​to acetone.

[0077] Example 2

[0078] Based on Example 1, this example provides an acetone gas sensor, a method for manufacturing the acetone gas sensor, and a method for detecting the acetone gas sensor.

[0079] The method for manufacturing the acetone gas sensor in this embodiment includes the following steps:

[0080] S1. Disperse the sensitive material sample powder in deionized water and stir it into a paste. Apply the paste to the surface of the alumina ceramic tube and then calcine the coated alumina ceramic tube. The sensitive material sample powder is the acetone gas sensor sensitive material described in Example 1.

[0081] Specifically, the sample powder obtained in Example 1 was dispersed in deionized water and stirred into a paste. The paste was then evenly coated onto the surface of the alumina ceramic tube using a brush. The alumina ceramic tube was then placed in a muffle furnace and the temperature was raised to 350°C at a rate of 1°C / min. The tube was then calcined at 350°C for 2 hours.

[0082] S2. A heating wire is passed through the calcined alumina ceramic tube. The calcined alumina ceramic tube is welded to a hexagonal base through the heating wires fixed at both ends and the through heating wire. Current is passed through the tube for aging to obtain a stable acetone gas sensor.

[0083] Specifically, two heating wires are fixed to each end of the alumina ceramic tube, and a heating wire is passed through the alumina ceramic tube, so that each end has three heating wires. The alumina ceramic tube is fixed to the hexagonal base by the six heating wires. Then, the sensor is inserted into the aging table and current is applied. It is left to age for 2-3 days. After the sensor resistance stabilizes, the acetone gas sensor is obtained.

[0084] Please see Figure 4 , Figure 4 This is a schematic diagram of an acetone gas sensor provided in an embodiment of the present invention. The acetone gas sensor includes a hexagonal base, a heating wire, and an alumina ceramic tube. The surface of the alumina ceramic tube is coated with the acetone gas sensor sensitive material prepared in Example 1. A heating wire runs through the alumina ceramic tube, and two heating wires are fixed to both ends of the alumina ceramic tube. The alumina ceramic tube is welded to the hexagonal base via the heating wires fixed at both ends and the through heating wire.

[0085] The gas sensor prepared using SnO2 / Zn2SnO4 sensitive material with cubic or octahedral morphology in this embodiment exhibits good selectivity for acetone, and has the advantages of low detection limit, high sensitivity, low cost, small size and simple operation. It is easy to integrate into mobile devices, and therefore suitable for the development of portable respiratory diagnostic instruments.

[0086] The detection method of the acetone gas sensor in this embodiment includes the following steps:

[0087] S1. The operating temperature of the sensor is controlled by controlling the temperature of the heating wire inside the alumina ceramic tube.

[0088] Specifically, the temperature of the heating wire inside the ceramic tube is controlled by the current of the current source meter, thereby controlling the operating temperature of the sensor. In other words, by controlling the current of the current source meter, the sensor can operate at different temperatures.

[0089] S2. At different operating temperatures, obtain the first stable resistance of the sensor in air and the second stable resistance in acetone, and use the first stable resistance and the second stable resistance to calculate the sensor's response value to acetone.

[0090] Specifically, the sensor's resistance changes when it is transferred from air to acetone gas and then back to air. The resistance is measured using a Fluke 8846a high-precision digital multimeter. The resistance when the sensor stabilizes in air is the first stable resistance, and the resistance when it stabilizes in acetone is the second stable resistance. The sensor's response to acetone is the ratio of the first stable resistance to the second stable resistance.

[0091] S3. Determine the target operating temperature of the sensor based on the sensor's response to acetone at different temperatures.

[0092] Specifically, the sensor was tested for acetone at different operating temperatures to obtain the response values ​​at each temperature. The operating temperature with the highest response value was selected as the target operating temperature. This target operating temperature corresponds to a specific value of the current source meter current. Therefore, the target operating temperature can be achieved by setting the specific value of the current source meter current. Specifically, the target operating temperature is 250℃, and the corresponding current source meter current is 120mA.

[0093] S4. At the target operating temperature, test the acetone gas using the sensor.

[0094] Specifically, the current source meter was set to 120mA, and the sensor was used to test acetone gas at a temperature of 250°C.

[0095] Please see Figure 5 , Figure 5 This is a curve showing the response value of the sensor to 100 ppm acetone as a function of operating temperature, provided in an embodiment of the present invention. The sensor was transferred to an environment with air as the background gas and remained stable, and the resistance at this point was marked as R. a The sensor was transferred to a gas of 100 ppm acetone, and the resistance was stabilized when marked as R. g The sensor's resistance gradually recovers to R when it is moved into the air. a The sensor's response to acetone is calculated using the formula S = R. a / R gThe calculations were performed. According to the test analysis, as the sensor's operating temperature increases, the sensor's response value first increases to a maximum value and then decreases. Furthermore, the gas-sensing performance of sample S2 is superior to that of sample S1. This is because the octahedral material exposes the (111) facet, while the cubic material exposes the (100) facet. For zinc stannate, the chemisorption energy of the (111) facet is higher than that of the (100) facet. The sensor using sample S2 as the gas-sensing material achieved the highest response to acetone at 250℃ (S = 16.31).

[0096] Please see Figure 6 , Figure 6 The response recovery time curve of the sensor provided in this embodiment of the invention to acetone at 250°C is shown. The sensor's response time (t) res ) and recovery time (t) rec The value is calculated based on the time required for the sensor to reach 90% of its resistance change during the response and recovery phases to acetone. Calculations show that the sensor responds to acetone in just 1 second and recovers in 80 seconds. This indicates that the sensor can achieve rapid response and recovery to acetone, which is highly advantageous for rapid detection in diabetic patients.

[0097] Please see Figure 7 , Figure 7 The graph shows the response curves of the sensor provided in this embodiment of the invention to different concentrations of acetone, with the horizontal axis representing the concentration of acetone. Comparison of the test data shows that even at 2.5 ppm, the response value of both samples can still reach 1.93, indicating that the prepared zinc stannate sensor has a low detection limit.

[0098] Please see Figure 8 , Figure 8 This is a bar chart showing the response values ​​of the sensor provided in this embodiment of the invention to different types of detection gases. In actual breath testing, multiple gases may be present; therefore, ammonia, formaldehyde, toluene, and acetic acid gases were selected for the sensor's selectivity based on the application environment. It can be seen that the sensor has the highest response value to acetone, indicating that the sensor has unique selectivity for acetone gas.

[0099] Please see Figure 9 , Figure 9 This is a graph showing the five-cycle test curve of the sensor for acetone provided in this embodiment of the invention. The sensor was tested in acetone gas at 250℃ and 100ppm. After each response / recovery, the sensor could repeat the response / recovery process, and the response value to acetone showed consistency. Finally, the device resistance returned to its initial state in each test. This indicates that the device has good repeatability during the test.

[0100] Please see Figure 10 , Figure 10 This is a stability test diagram of the sensor provided in an embodiment of the present invention. To evaluate the stability of the device, the sensor underwent a continuous 20-day gas-sensing performance test. The data shows that during the 20-day test, the sensor's response value remained around 16.31, with very small fluctuations, indicating that the sensor has excellent stability.

[0101] The zinc stannate gas-sensitive material provided by this invention has different morphological characteristics. Gas sensors prepared using this material exhibit good selectivity for acetone, and the sensor has low initial resistance, making it highly practical.

[0102] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. An application of a gas sensor based on SnO2 / Zn2SnO4 sensitive material in detecting acetone in respiratory gases, characterized in that, The preparation method of the SnO2 / Zn2SnO4 sensitive material includes the following steps: S1. Weigh out tin chloride hydrate and zinc acetate and disperse and dissolve them in deionized water to obtain a mixed solution; S2. Weigh out lithium hydroxide and dissolve it in the mixed solution to obtain a reactant solution; S3. Stir the reactant solution at a preset temperature for a preset time to allow the tin chloride hydrate, zinc acetate, and lithium hydroxide to react and obtain the reaction product; S4. The reaction products are purified and dried sequentially. S5. The dried reaction product is calcined to obtain the SnO2 / Zn2SnO4 sensitive material; the SnO2 / Zn2SnO4 sensitive material has a cubic morphology, and the exposed crystal face of the cubic morphology is the (100) face; or, the SnO2 / Zn2SnO4 sensitive material has an octahedral morphology, and the exposed crystal face of the octahedral morphology is the (111) face; the exposed crystal face (100) of the cubic morphology or the exposed crystal face (111) of the octahedral morphology is used to selectively adsorb acetone in the respiratory gas.

2. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 1 in detecting acetone in respiratory gas, characterized in that, The mass of the tin chloride hydrate is 0.7g, the mass of the zinc acetate is 0.439g, the volume of the deionized water is 60ml, the mass of the lithium hydroxide is 0.192g, the preset temperature is 85℃, the preset time is 6h, and the sensitive material has the cubic morphology.

3. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 1 in detecting acetone in respiratory gas, characterized in that, The mass of the tin chloride hydrate is 0.7g, the mass of the zinc acetate is 0.439g, the volume of the deionized water is 60ml, the mass of the lithium hydroxide is 0.528g, the preset temperature is 85℃, the preset time is 6h, and the sensitive material has the octahedral morphology.

4. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 1 in detecting acetone in respiratory gases, characterized in that, Step S4 includes: The reaction product was washed three times with deionized water and ethanol alternately to remove impurities and obtain a purified reaction product. The purified reaction product was dried in a vacuum drying oven at a temperature of 60°C.

5. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 1 in detecting acetone in respiratory gases, characterized in that, Step S5 includes: The dried reaction product was placed in a muffle furnace and heated to 600°C at a heating rate of 2°C / min. The product was then calcined at 600°C for 2 hours. After calcination, the sensitive material was obtained.

6. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 1 in detecting acetone in respiratory gases, characterized in that, The method for manufacturing the gas sensor includes the following steps: S1. Disperse the SnO2 / Zn2SnO4 sensitive material sample powder in deionized water and stir it into a paste. Apply the paste to the surface of the alumina ceramic tube and then calcine the coated alumina ceramic tube. S2. A heating wire is passed through the calcined alumina ceramic tube. The calcined alumina ceramic tube is welded to a hexagonal base through the heating wires fixed at both ends and the through heating wire. Current is passed through the tube for aging to obtain a stable acetone gas sensor.

7. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 6 in detecting acetone in respiratory gas, characterized in that, The gas sensor includes: a hexagonal base, a heating wire, and an alumina ceramic tube, wherein... The surface of the alumina ceramic tube is coated with an acetone gas sensor sensitive material, and a heating wire runs through the alumina ceramic tube. Heating wires are fixed at both ends of the alumina ceramic tube. The alumina ceramic tube is welded to a hexagonal base by heating wires fixed at both ends and through which heating wires pass.

8. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 7 in detecting acetone in respiratory gas, characterized in that, The method for detecting acetone in breath gas using the gas sensor includes the following steps: S1. The operating temperature of the sensor is controlled by controlling the temperature of the heating wire inside the alumina ceramic tube; S2. At different operating temperatures, obtain the first stable resistance of the sensor in air and the second stable resistance in acetone, and use the first stable resistance and the second stable resistance to calculate the response value of the sensor to acetone. S3. Determine the target operating temperature of the sensor based on the sensor's response to acetone at different operating temperatures; S4. At the target operating temperature, test the acetone gas using the sensor.

9. The application of the gas sensor based on SnO2 / Zn2SnO4 sensitive material according to claim 8 in detecting acetone in respiratory gas, characterized in that, The target operating temperature is 250℃.

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