Research On The Design And Performance Of Tungsten Oxide Quantum Dot Surface Acoustic Wave Gas Sensor

Due to the problems caused by air pollution in the environment,the demand and requirements for gas sensors are increasing.Gas sensor can detect the species and concentration of gas.The Surface Acoustic Wave(SAW)gas sensor has a lot of advantages,such as high resolution,good reproduction performance,and strong anti-interference ability,which is in line with the development direction of system digitization and integration.Tungsten oxide colloidal quantum dots is a kind of low dimensional nano-material,which can be compatible with a variety of substrates.It can be treated with solutions and has a large surface area,which can be detected at room temperature.The main work of this paper is the synthesis of tungsten oxide colloidal quantum dot gas sensing film,the design and performance research of SAW gas sensor.In our work,COMSOL software was used to design and optimize the structure of SAW device.By adjusting various parameters,combined with the simulation results,we synthesized the SAW wafer by light source lithography.Then the solvothermal method was adopted to adjust the particle size of WO₃ colloidal quantum dots.By optimizing the film forming process,the SAW sensor was fabricated which can detect H₂S gas at room temperature.The Cu Cl₂ solution was used to remove the organic long chain coated on the surface of tungsten oxide colloidal quantum dots through the film level ligand replacement.Thus,the SAW gas sensor based on WO₃ colloidal quantum dots sensing film was obtained.The gas sensing properties of SAW gas sensor to H₂S at room temperature were tested.The results showed that the change of sensor frequency is about 4000 Hz,the response time is 255 s,the recovery time is about 337 s.The low detection limit of H₂S we tested was1ppm at room temperature.Based on the control experiment and simulation results,the change of gas sensing film conductivity of the SAW sensor was caused by the acoustic electric effect.When the sensitive film adsorbs H₂S,the conductivity of gas sensitive film changes,and the change of film reactance reflects the change of resonance frequency measured by the network analyzer.This work provides theoretical basis and corresponding experimental method for the design of SAW gas sensor with low power consumption.