Study On Surface Acoustic Wave Nitrogen Dioxide Gas Sensor

Because Surface Acoustic Wave (SAW) gas sensor has a lot of good properties such as high sensitivity, stability, small size and easy integration, it has received great attention from scientists and it has become a hot topic in the field of sensor technology. As a sensitive film, SAW gas sensor testing of gas in the central part of its sensitivity, stability, selective, performance of the sensor important factors. However, due to the SAW design and production processes, their performance is not satisfactory. In this paper, a SAW gas sensor was designed and developed a frequency of 120MHz dual-channel SAW delay-line sensor devices which combined to e-beam lithography, X-ray lithography and lift-off technology. This SAW sensor device using MWCNT/WO3 and MWCNT/Polyaniline at room temperature-sensitive membrane can be detected NO2 gas successfully.Main research topics include:(1) Summarized the SAW gas sensors basic theory and background in the overview. Compared the domestic and foreign SAW gas sensors development status and discussed the future of SAW gas sensor study trends.(2) Introduced the theory of SAW sensors:piezoelectric Rayleigh wave and its application in the nature of the surface acoustic wave generation and reception theory, especially Inter-digital transducer (IDT, Inter-Digital Transducer) features and parametric analysis which is good for the device design.(3) Study of SAW gas sensor design parameters of the options, including the substrate material and electrode material selection, design of oscillator, design of IDT and other issues. Studied the SAW sensor processing technology deeply, formulate a reasonable and sensitive film SAW sensor selection techniques route.(4) Analyzied and studied the sensitive film, choose the MWCNTS/Polyaniline and MWCNTS/WO3 sensitive film NO2 gas as the test material. It was observed that the sensors had a high sensitivity, good repeatability and low detection limit.