Research On Multi-parameter Integrated Sensing Technology Based On SAW Resonator

In the fields of health care,aerospace,agricultural production and energy industry,realtime monitoring of parameters such as temperature,humidity,vibration and pressure is of great significance.The surface acoustic wave(SAW)sensor uses the mutual conversion of mechanical wave and electromagnetic wave to realize the characteristics of wireless transmission and passive measurement,making it an ideal choice for realizing simultaneous monitoring of multiple parameters.Although there have been reports about SAW integrated sensors,these papers mostly use delay line SAW sensors,which encode and extract information through the setting of reflection grids.The resonant SAW sensor adopts a reflective grating to form an acoustic resonant cavity,and the surface acoustic wave has less loss during propagation and a longer transmission distance.Aiming at the real-time measurement requirements of various environmental parameters,this paper proposes a design method of surface acoustic wave multi-parameter integrated sensor.According to the testing requirements of temperature,humidity and pressure,the design of the sensor was completed through simulation and theoretical analysis.The SAW resonant temperature-humidity-pressure(T,H,P)integrated sensor was prepared and tested and analyzed.Aiming at the needs of high temperature testing,the surface acoustic wave sensor using LGS as the base material was simulated,and the finite element models of the sealed cavity,cantilever beam and accelerometer were established and analyzed and optimized;the LGS wet etching and thermocompression bonding process were studied Laid the foundation for the next experimental research.The research work of this article is:1.The design method of temperature-humidity-pressure integrated sensor of resonant surface acoustic wave is proposed,and the surface acoustic wave heat transfer model,pressure deformation model and S-parameter calculation model are established;the frequency shift of the humidity sensor unit is derived according to the Sauerbrey equation Calculation formula: According to the simulation and calculation,the frequency drift range of the temperature,humidity and pressure sensing units are obtained respectively,and the resonance frequency and bandwidth distribution of each sensing unit are reasonably set accordingly.2.Tested the surface acoustic wave temperature-wet-pressure integrated sensor.The test results show that the temperature sensitivity of the temperature sensing unit reaches 5.16 k Hz / ° C in the range of 40-200 ° C;the frequency shift of the humidity sensing unit in the range of 10-90% RH reaches 0.4 MHz,and the absolute humidity sensitivity is 5.1 k Hz /% RH;the pressure sensing unit is in the 0-42 k Pa measurement range,and the sensitivity is 0.9 k Hz / k Pa.The dynamic humidity test results also show that the sensor's humidity response and recovery time are 8.3 s and 4.8 s,respectively.3.The finite element model of the sealed cavity and cantilever beam of gallium lanthanum silicate(LGS)was established,and the displacement and strain distribution of the cavity were obtained by compressive analysis of the sealed cavity model.The shape and crystal of the sealed cavity were cut.The optimization has been carried out;the acceleration and modal analysis of the cantilever beam model were carried out to obtain the displacement,strain distribution and resonance mode of the cantilever beam.The size of the cantilever beam was optimized and the modal analysis caused the resonance to the cantilever beam.Structural damage.At the same time,a small-size surface acoustic wave triaxial accelerometer is proposed,and the design principle of the accelerometer is verified by the finite element model.4.Wet etch and hot-press bonding technology research on lanthanum gallium silicate material.The wet etching process and parameters were studied,and a practical and practical lanthanum gallium silicate microstructure etching process was obtained: the cavity structure was etched on the surface of the lanthanum gallium silicate substrate;the hot pressing of lanthanum gallium silicate was studied The temperature loading curve of the bonding process,bonding pressure and other parameters initially obtained the process of the hot-press bonding of lanthanum gallium silicate: the sealed cavity of gallium lanthanum silicate was manufactured by wafer bonding.The related achievements made preparations for the next experimental study of the research group.