Electromechanical Coupling Design Of Piezoelectric Micro-mass Sensor

Due to excellent characteristics of no labeling,high sensitivity and easy detection,piezoelectric cantilever biosensors have great application potentials in biometrics,environmental anomaly detection and particle weighing.Traditionally,resonant micro-mass sensor are used to weigh analyte by measuring the resonant frequency change before and after the micro-mass adsorption,which requires a frequency sweeping procedure,thus resulting the drawbacks of low anti-jamming performance to environmental damping,time-consuming and high detecting cost for real-time online measurement.Hence,the mass detection method based on impedance change at a fixed frequency point is experimentally proposed for real-time monitoring like liquid concentration or virus growth.However,it is still in the stage of experiment validation and lacks of effective methods for analyzing and improving impedance sensitivity.In this paper,considering the electromechanical coupling effects,a impedance sensitivity model for the piezoelectric sensor,and correspondingly the sensitivity improving method is obtained based on circuit tuning,and furthermore,a high-sensitivity micro-mass sensor design method is proposed based on collaborative optimization of structure and circuit.The high-sensitivity features of the sensor piezo-electric drive components and the layout of the sensor components demonstrate experimentally the effectiveness of the proposed high-sensitivity sensor design method,including:?1?Impedance sensitivity model considering the electromechanical coupling effects.Based on the equivalent circuit model of the piezoelectric element,the sensor impedance sensitivity model is established considering the influence of the additional circuit on the dynamic response of the resonant sensor,and the influence of circuit elements like inductance,excitation frequency,and structural parameters on the sensitivity is studied.It is shown that shunt inductance can effectively improve the sensitivity of the sensor's impedance.Then,a piezoelectric sensor of 21.0 mm long is fabricated and tested,whose impedance sensitivity can reach 1.62×10⁷?/g compensated by a inductance of 0.6 while the frequency shift sensitivity is1.0×10⁴Hz/g with the same geometric size.For ease comparison,a uniform dimension of sensitivity expression is introduced,and the sensitivity of the impedance can reach 156/g,which is 55.7 times the sensitivity of frequency difference 2.8/g.?2?High-sensitivity micro-mass sensor design method based on collaborative optimization of structure and circuit.The influence of circuit form,electric circuit components?inductance,capacitance and resistance?and structural parameters?piezoelectric and structural parameters?on sensor sensitivity is systematically studied.A high-sensitivity micro-mass sensor design method based on collaborative optimization of structures and circuits was established.When the length is 25 mm,the structural parameters can be optimized to achieve an impedance sensitivity of 7.09×10¹¹?/kg.The impedance sensitivity under the unified dimension is frequency sensitivity.The 82.5 times of the circuit and the collaborative optimization design of the circuit and structure can make the impedance sensitivity reach 1.96×10¹³?/kg,the frequency difference sensitivity is 5.17×10⁷ Hz/kg,and the uniform dimension sensitivity is increased by 91.3 times;?3?Resonant micro-mass sensor piezoelectric layer layout optimization design.Taking the layout and size of the piezoelectric sensor as the design variable,the piezoelectric layer layout optimization design model of the resonant micro-mass sensor is established with the goal of maximum sensitivity,and the layouts of piezoelectric actuators and sensors with high sensitivity characteristics corresponding to different numbers of different piezoelectric crystals are obtained,and which shows that the impedance measurement sensitivity of the three stage piezoelectric elements is 8.38 times of that of the single-stage piezoelectric film.