Design Of High Sensitivity Resonant Sensor's Structure Based On Modal Localization

The weakly coupled resonant sensor based on modal localization can produce local concentration effect of energy because of tiny mass interference,so as to detect micro-mass according to the vibration mode change.Compared with the traditional single-degree-of-freedom sensor,it has the advantages of high sensitivity,common mode suppression,and strong resistance to environmental interference.It has wide application prospects in the field of environmental abnormality monitoring.This paper proposes a dual-piezoelectric cantilever weakly coupled resonant sensor structure,and establishes a micro-mass real-time measurement method that uses the impedance change at a fixed frequency as an indicator,which can achieve online measurement of tiny substances;further,the effects of structural parameters,coupling structure and internal resonance on the amplitude sensitivity and impedance sensitivity of resonant sensors are explored,and a design method to effectively improve the sensitivity of the sensor is given.Specific work includes:(1)The dynamic model of the piezoelectric weakly coupled resonant sensor is established.The piezoelectric equivalent circuit method is used to derive the sensitivity evaluation index based on the amplitude and impedance changes.The influence mechanism of external disturbance(micro-mass change)on the vibration characteristics of the system is studied,under the premise of a unified sensitivity description method,the paper compares three sensitivity evaluation indicators such as relative frequency change,relative amplitude change,and relative impedance change systematically.The results show that the amplitude sensitivity is 310.45(1/g),which is much higher than the frequency Differential sensitivity(3.22)and impedance sensitivity(44.60).(2)The relationship between the structural parameters and coupling forms on the sensitivity of the sensor is studied.The results show that with the optimization of structural parameters and position,the sensitivity can be increased by 33.40%,and the width of the cantilever beam,the thickness and length of the piezoelectric film have little effect on the sensitivity.In addition,on the premise of ensuring the consistent coupling stiffness,the coupling structure has a significant effect on the sensor sensitivity.Changing the single-beam coupling structure to a double-beam type can increase the amplitude sensitivity by 47.6%,and changing it to a three-beam type can increase the amplitude sensitivity.340.55%.(3)A high-sensitivity sensor structure design scheme based on 1:3 internal resonance is proposed,and a new micro-mass measurement method using low-frequency beams for adsorbing the measured object and high-frequency beams for amplitude detection is given,so that the amplitude sensitivity is 6.15 times higher than that of the 1:1 symmetrical structure.