Optimal Design on SAW Strain Sensing Device at High Temperature Employing AlN Piezoelectric Thin-film

摘要

Sensing strain of high-temperature components in the fields of aerospace and nuclear power is of great significance to ensure accurate operation and safe production of equipment. To obtain strain information at extreme high temperature environment, a SAW strain sensing device employing composite structure of Al_2O_3/IDTs/AlN/Metal/Diamond was proposed. Al_2O_3 is filled between the IDT electrodes to increase electrode reflectivity, allowing reduction of acoustic losses and improvement of device temperature stability. Obviously, high performance as Q-value and low insertion loss of the sensing chip is the key for achieving successful wireless strain sensing system. In this work, the SAW propagation characteristics in multi-layered composite structures was analyzed by using finite element method (FEM), and corresponding simulation parameters in coupling of modes (COM) model was extracted theoretically. High Q-value and excellent temperature stability were achieved from the proposed SAW sensing device structure using the determined design parameters.