Wireless Passive Temperature/Pressure Integrated Surface Acoustic Wave Sensor Based On Lithium Niobate

Aerospace vehicle in flight is often accompanied by high temperature,high spin,high pressure and other harsh environment,especially the local temperature of hypersonic vehicle surface,aeroengine and gas turbine and other key parts even exceed thousands of degrees Celsius.Therefore,in-situ real-time acquisition of temperature,pressure and other parameters in harsh environment is of great significance for material selection,structural design and protective measures of spacecraft.At present,the traditional wireless passive sensor has the shortcomings of single structure and short transmission distance,which limits its multi-parameter testing ability in harsh environment.In order to meet the requirement of real-time on-site measurement of temperature/pressure dual-parameter in high temperature and high speed environments such as aerospace vehicle and engine,a novel passive wireless sensor structure based on surface acoustic wave(SAW)and lithium niobate piezoelectric materials with two-parameter sensitive unit integrated is proposed in this paper.The research work and innovation are as follows.1.The propagation mechanism of SAW and the classification of SAW sensors are studied.Then,the basic structure of SAW sensors is introduced,and the corresponding relationship between the structural parameters and the performance of sensors is established.2.The theoretical model of SAW sensor is analyzed,and the influence of sensor structure parameters on the performance of SAW sensor is also discussed.COMSOL Multiphysics software was used to simulate the effect of metal electrode materials on the resonant frequency of the sensor.3.Based on the analysis of the sensitive mechanism of temperature and pressure of SAW sensor and the principle of antenna design,a temperature/pressure integrated sensor structure based on lithium niobate is proposed.Then,the parallel resonant integrated pressure and temperature dual-parameter sensor is designed and fabricated.4.Temperature and pressure tests of SAW sensors prepared have been completed respectively.Temperature measurement range is 25? ~325?.The test results show that the temperature sensitivity of temperature resonator and pressure resonator are 1.34 kHz/? and 1.35 kHz/?,respectively.The pressure test of the sensor is done at different temperatures,ranging from 0 to 1000 gf,and the test results show that the maximum pressure sensitivity is 10.5 kHz/100gf.