Investigation Of Passive And Wireless Pressure Sensor Based On Surface Acoustic Wave Resonator

Pressure sensors have a large share in the sensors’ market. With high sensitivity, high Q value, small volume, low manufacturing cost, ease of integration and the advantages of the passive wireless measurement, surface acoustic wave pressure sensors have great advantages and application prospect in the sensor application field. So the research for surface acoustic wave pressure sensors has the vital significance.In this paper, the related theory of surface acoustic wave devices was studied. The characteristics of the piezoelectric materials that applied to the SAW devices were compared, such as electromechanical coupling coefficient, velocity of SAW, temperature coefficient, etc. These provided a basis for the optimal selection of substrate. The structural parameters of the device were studied, such as the size of IDT and reflectors, the thickness of the metal film, etc.Then the piezoelectric substrates were modeled and analyzed with the finite element analysis software COMSOL Multiphysic. The best place to lay the SAW resonator was determined where it has the highest sensitivity. And then the SAW resonator was modeled, the eigenfrequency, frequency response, frequency response with loading, and the influence of sound aperture on frequency response etc. were analyzed. Those provided the basis for the reasonable design of the device.To ensure the quality of the device, the micro processing technology for the fabrication of SAW devices was studied. Then the fabrication of SAW device was finished. The electron gun evaporation and magnetron sputtering were compared, their advantages and disadvantages were analyzed; photoresist spin coating process was studied, the relevant parameters were determined; the laser direct writing process and the etching process were researched. After fabrication, the SAW resonator was tested with the network analyzer. The test results showed that the central frequency was very close to the design. So the device has strong usability.In this paper, the fundamental research for SAW pressure sensor was finished. This has laid a certain foundation for its practical application and the marketization.