Surface acoustic wave pressure sensor

Abstract

The invention discloses a surface acoustic wave pressure sensor with small volume and high sensitivity, mainly comprising a top cover and a base which is penetrated through by two metal electrodes, wherein the top cover is installed on the base in a sealing way, a pressure transmitting via hole is arranged on the base, a fluid membrane is fixed on the inner surface of the base in the sealing way and covers the pressure transmitting via hole, a closed cavity is formed among the base, the top cover and the fluid membrane, a strip-shaped substrate is fixed on the fluid membrane and bestrides the pressure transmitting via hole, a surface acoustic wave pressure sensing resonator, a surface acoustic wave reference resonator and two bonding pads are fixed on the substrate, the surface acoustic wave pressure sensing resonator is arranged just opposite to the center part of the pressure transmitting via hole, respective both ends of the surface acoustic wave pressure sensing resonator and the surface acoustic wave reference resonator are respectively connected with the two bonding pads, the two metal electrodes are arranged at one end in the closed cavity to be respectively connected with the two bonding pads, and frontalprojected area of a pressure sensitive region on the substrate is smaller than the area of the cross section of the pressure transmitting via hole.

Description

technical field [0001] The invention relates to a surface acoustic wave pressure sensor. Background technique [0002] The surface acoustic wave pressure sensor can be used to detect mechanical or fluid pressure. The pressure to be detected acts on the piezoelectric substrate, causing the substrate to deform, and the speed of surface acoustic wave propagation on the substrate changes, resulting in acoustic The resonant frequency of the surface wave resonator changes, and the pressure value acting on the substrate can be obtained by detecting the change of the frequency. When the pressure to be measured is inside an inaccessible or moving object, SAW sensors are favored due to their passive and wireless advantages. [0003] At present, most surface acoustic wave pressure sensors on the market are used under the conditions of high measurement environment pressure and low measurement sensitivity requirements, such as wireless detection of automobile tire pressure and cylinder ...

AI Technical Summary

Problems solved by technology

But on the one hand, such a structural design increases the complexity of fabrication, installation and packaging design

For example, firstly, the substrate used in the above-mentioned patent on the cantilever beam structure needs to engrave a cantilever beam structure on the original rectangular substrate through an etching process, which makes the fabrication of the substrate more complicated; It is difficult to fix one end of the cantilever beam and align the other stressed end with the smaller fluid diaphragm below; moreover, compared with the design and installation structure mentioned in the above-mentioned Chinese patent CN101248339A, it is more difficult in terms of structural stability. Difference

Images