In order to solve the environmental protection problem of traditional lead-containing sensors

a MEMS acoustic sensor based on potassium sodium niobate(KNN)lead-free piezoelectric thin-film is designed

and the finite element analysis method in COMSOL Multiphysics is adopted to analyze and optimize its emission performance.Two finite element models of the sensor are constructed;mcluding a composite piezoelectric plate and a sensor with actual substrate support.The equivalent model of the composite piezoelectric plates is used to optimize key geometric parameters

such as device radius

piezoelectric layer/neutral layer thickness

and upper electrode plate radius.The analysis found that the resonance frequency is negatively correlated with the device radius and positively correlated with the thicknesses of the piezoelectric layer and the vibration layer.When the ratio of the upper electrode plate radius to the device radius is 1︰2

and the ratio of the thickness of the KNN layer to the Si layer is 2︰1

the device exhibits the optimal displacement response.Simulation results show that the emission performance of the optimized sensor is significantly improved

and it is suitable for ultrasonic emission scenarios.This paper provides a reliable numerical basis for the preparation and performance regulation of lead-free piezoelectric MEMS acoustic sensors.