Preparation And Research Of Graphene-based MEMS Gas Sensor Modified By Bimetallic Oxide

With the continuous deepening of the research on graphene materials and MEMS technology,its application potential in the field of gas sensors has also been gradually explored.The new gas sensor based on graphene gas-sensitive material,combined with MEMS technological design and fabrication,has a large research value because it combines the advantages of low reaction temperature,high gas-sensitive performance of graphene material and low power consumption,high sensitivity of MEMS chip.Based on the above background,this thesis prepares and researches a graphene-based MEMS gas sensor modified by bimetallic oxide.The bimetallic oxide Cu O/In₂O₃ was modified on the surface of the reduced graphene oxide r GO to prepare a gas-sensitive composite material.To address the problem of residual intermediate products in graphene-based composites prepared by one-step hydrothermal method or solvent thermal method,a method of preparing a single material in one step and graphene-based composites by one-step ultrasonic hydrothermal is investigated,and the r GO-Cu O/In₂O₃ material prepared based on this method has very few residual intermediate products and does not affect the gas-sensitive performance by characterization.Design a new type of MEMS chip with a laminated structure,and build a three-dimensional structure model of the chip.The finite element method is used to conduct structural thermodynamic analysis of the chip to obtain the temperature,deformation and stress distribution of the chip to verify the rationality of its structural design.Aiming at the problems of low accuracy of results and low computational efficiency in finite element analysis of chips,a distributed meshing method is studied,and the cell quality of the structured mesh model of chips established based on this method is checked to be of high quality and can achieve higher accuracy analysis.On the basis of this study,a method of using higher-order cells to build a finite element model with contact connections is investigated,and the chip finite element model optimized based on this method has higher computational accuracy and efficiency after comparative analysis.Use MEMS technology to prepare gas sensor,and test the sensor’s gas sensitivity.The analysis of the data shows that the sensor has a strong gas-sensitive response to 20-200ppm ammonia,the response sensitivity increases with the increase of ammonia concentration,the response time is about 98s,the recovery time is about180s,the gas selectivity is strong,and the stability is good.The investigation of the gas response principle shows that the p-n type heterostructure introduced when Cu O/In₂O₃ is modified on the r GO surface improves the gas response performance of the sensor.