Theory Study On Surface Acoustic Wave Oxygen Sensor Under High Temperature Bias

As a new branch of sensor family, Surface Acoustic Wave(SAW) sensor has unique advantages, so much attentions have been paid to it as soon as it appeared. After ceramics, semi conducts and optical fiber sensor, it has become an important direction coincided with the future sensor developing trend. Since the phenomenon of conductance of Cu20 changes when it absorbs vapor was discovered by P.Brauer in 1931, more and more material such as ZnO,Fe203,MgO, SnO2, NiO, Cr2O3, TiO2, BaTiO3,, Nb205 be provided with same character. Using the absorption effect, many kinds of gas sensor have been developed. Absorption effect gas sensors have developed a new system of senor family. SAW gas sensor has splendid future in burn control, environmental protection and secure protection. The high temperature SAW oxygen sensor base on SAW technical and nano titania film was researched in this paper.Starting with the constitutive and motion equation of piezoelectric crystal, in virtue of elasticity mechanics and continuous medium mechanics, the universal wave equation for gas sensor layer structure was established, and the solve process of wave equation was presented. Starting form the gas sensor is work on high temperature, the universal temperature bias electroelastic wave equation was established using Lanragian coordinate in initial configuration in this paper. Based on researching on the physical meaning of effective material constants and its determining method, considering the different of effective constants and basic constants, consulting the solve process of normal wave equation, the solve process of high temperature bias layer structure for as sensor was presented. Using perturbation theory, the effects of mechanism perturbation and electrics perturbation were discussed respectively. Combining with absorption method, the conclusion is in the limits of the paper, the effects of mechanism perturbation can be ignored, and the output only determined by electrics perturbation.Cooperate with SIC, preparing nano titania sensoring film for high temperature SAW oxygen sensor and get optimized artifice for performance nanostructure titania film. The constants of sensor film were measured.The high temperature SAW oxygen sensor was designed and special experiments oscillator circuit was fabricated in this paper. The theory results and agreed with the experiment ones very well.In this paper, the universal design theory for high temperature SAW gas sensor was established. To the application of SAW high temperature gas sensor, the complete software package for solving temperature bias SAW and perturbation question was developed, which provided necessary calculation tool for SAW gas sensor. Some cuts of SiO2 crystal were calculated. The theory and experiment in this paper provide reference and direction significance for gas sensor design and provide good foundation for the progress and practice of the gas sensor.