Research On The Characteristics Of Acoustic Surface Wave Gas Detection Device

Compared with the traditional terms of gas detection devices, SAW devices have high precision, small size, low power consumption, and are suitable for long-distance transmission. Many factors will affect the performance of surface acoustic wave devices such as piezoelectric materials, selection-cuts and propagation directions, the design of the inter-digital transducers, materials of the sensitive film, this paper will study on the above three aspects.The type and the shear type of the piezoelectric materials were determined by the study of SAW velocity and electromechanical coupling coefficient of the piezoelectric materials. This paper used the finite element method(FEM) simulation software COMSOL Multiphysics 5.0 to study the propagation process of the SAW on the symmetry and the asymmetry mode, then demonstrated the result of the simulation. The main factors that affect the properties of the IDTs and the influence of the secondary effects of electrode have been discussed, and a good design of the SAW device have been came up by FEM.The IDTs were fabricated which size were 5μm and 10μm on the surface of the lithiumniobate piezoelectric crystal. The processes of the fabrication were given. And it was successful to fabricate the device and the zinc oxide sensing film by Magnetron Sputtering(MS) method as the SAW gas detection device, the XRD and SEM devices were used to test the film. At the end of this paper two types of the SAW gas detection devices were set up, and the delay line SAW nitrogen dioxide gas detection device was fabricated.