Characteristics of thickness-shear modes excited by two layers of piezoelectric films in acoustic sensors

Abstract

The thickness-shear mode (TSM) excited by two layers of (112(–)0) textured hexagonal piezoelectric films are studied to improve the performances of acoustic sensors. The corresponding researches are carried out by the acoustic wave propagation model which considers the effects of the acoustic attenuations. When the acoustic field and electric field satisfy to a special match condition, i.e. the phase variation of TSM at each film equal to π, both piezoelectric layers with opposite polarization directions reduce the first TSM and generate the second TSM with higher frequency and higher quality factor than the first TSM excited by two-layers of piezoelectric films with identical polarization direction. Furthermore, the second enhanced TSM holds a moderate the ratio of the operating frequency to the quality factor. These properties of the TSM are appropriate for improving the mass sensitivity and sensitive resolution of the acoustic sensors in liquid medium. Acknowledgment: This work is supported by National Natural Science Foundation of China (No. 11004099 and 11174142), State Key Laboratory of Acoustics of Chinese Academy of Sciences, and also PAPD of Jiangsu Higher Education Institutions.