Theoretical and experimental study of gravimetric sensitivity of transverse plate mode resonators [French]

摘要

Surface Acoustic Wave devices are frequently used For oscillator stabilization and frequency filtering in the range 30 MHz-3 GHz. Although most of these devices are based on a Rayleigh wave propagation, many works have been devoted to Surface Transverse Wave (STW) propagation fur the design of high purity spectrum resonators, because of their high phase speed and of the particularly high Q factors obtained with STW resonators. On the other hand, Acoustic Plate Modes (APM) have been widely studied to design and fabricate delay lines mainly used for sensing applications. In order to improve the rather small Q factor and large insertion losses of such transverse wave devices, this paper demonstrates the interest in coupling both principles of APM and STW In these devices, the waves are trapped by metal strip grating deposited on a thin quartz plate. A theoretical model developed for the investigation of STW propagation under periodical surface corrugation has been adapted to the case of transverse wave propagation in a thin quartz plate. Synchronous resonators have been implemented on singly rotated quartz plates and resonant frequency measurements have shown the validity of the proposed model. re small insertion losses and large Q factor measured are close to the stare of the art of STW resonators and consequently much better than classical APM device ones. Gravimetric sensitivity of these devices has been studied to check their sensing potentiality. Theoretically, this characteristic can be easily deduced from the previous model, and an experimental calibration has been done, allowing one to compare the proposed devices to classical gravimetric sensors. Sensitivity of resonators built on AT-cut and Z-cut quartz plates have been respectively measured with Aluminum and Chromium deposition. The strong differences of the resonator response in each cases underlines the influence of the elastic properties of the metal on the sensor behavior. [References: 27]