Research On Nano-tin Dioxide Four-array Silicon-based Integrated Gas Sensor

At present,China has developed into a country with a large production and consumption of chemical energy.However,the frequent occurrence of toxic gas leaks and explosions in chemical plants has brought great threats to people's production and life safety.In addition,a large amount of gases such as benzene and formaldehyde released by the decoration materials used in home decoration have also caused serious harm to human health.Among them,formaldehyde is on the top of China's priority list of toxic chemicals.Due to the shortcomings of the current hazardous chemical gas detection methods such as large size,large power consumption,high cost,complicated operation,poor selectivity,and poor stability,they cannot meet the needs of modern detection.Therefore,it is necessary to develop a new type of integrated sensor that is portable,has high sensitivity,fast response speed,and can detect multiple gases.This topic aims at the shortcomings of traditional detection technology and the current intelligent and networked needs of the domestic market.Through the analysis and discussion of the gas sensing mechanism and sensor performance of semiconductor metal oxide sensitive materials,combined with the preparation process of silicon-based MEMS microstructure sensors And array integration,a four-array silicon-based integrated gas sensor based on nano-tin dioxide gassensitive materials is designed.And each sensor unit is different,enabling it to achieve high-precision,high-speed,low-power real-time monitoring of a variety of toxic and harmful gases.The main research contents are as follows:1.A silicon-based microstructure sensor is designed.The MEMS sensor structure and the materials of each part were designed according to the requirements of this subject;the temperature distribution simulation and thermal stress analysis of the sensor were performed by ANSYS finite element analysis software;the microstructure was optimized based on the results,and the designstructure and process were verified Rationality and feasibility..2.The tin dioxide sensitive material was prepared by the sol-gel method,and was doped with chloroplatinic acid and antimony trioxide to improve the gas sensing performance.The differential calorimetry analysis was used to ensure the complete calcination of the oxide.The scanning electron microscope analysis verified The gas-sensitive material particles are nano-sized to ensure the specific surface area and improve the sensing characteristics.The tin dioxide double-layer film modified with the alumina catalytic layer improves the selectivity.3.A silicon-based MEMS sensor array was prepared.A silicon-based micro-hot plate gas sensor was prepared by magnetron sputtering,oxidation,and photolithography.After the surface was coated with different sensitive films,four MEMS sensor chips were integrated on the same circuit board,and the soldered leads and Follow-up processes such as sensor packaging.4.The performance test was performed on the integrated sensor array.The gas detector detects and analyzes the concentration characteristics,sensitivity characteristics,response-recovery characteristics and selectivity of the sensor array.The four channels of data collected were compared and analyzed.By changing the way the gas-sensitive material is doped and coated with the surface modification layer,the four units in the sensor array respectively achieve the quantitative detection of four typical toxic and harmful gases: ethanol,formaldehyde,ammonia and benzene;the performance of the sensor is completed The evaluation verified the feasibility of the system.5.Thermal theory of sensor microstructure,the gas sensing mechanism,doping mechanism of nano-tin dioxide and the catalytic mechanism of the surface modification layer were discussed.The produced sensor array can realize: the sensor A1 unit detects the ethanol vapor,the measurement range is 0.25-250 ppm,the response time is 20 s,and the recovery time is 38s;the sensor A2 unit detects the formaldehyde vapor,the measurement range is 0.5-200 ppm,the response The time is 6s and the recovery time is 18 s.The sensor B1 unit detects the ammonia gas,the measurement range is 1-850 ppm,the response time is 20 s and the recovery time is 35s;the sensor B2 unit detects the benzene vapor,the measurement range is 0.5-160 ppm.The response time is 35 s and the recovery time is 48 s.The consistency andrepeatability of each unit of the sensor array are average.