A SH-APM liquid viscosity sensor based on PZT-5H

Viscosity is one of the characteristic parameters of liquid. The measurement of liquid viscosity is required in many applications. Compared with other acoustic wave device, the shear-horizontal acoustic plate mode wave (SH-APM) device is suitable for liquid sensing. In this paper, the theoretical model of SH-APM device loaded with viscous liquid is built using the propagation characteristics of acoustic wave in laminated mediums, the liquid viscosity is introduced by adding the imaginary part in liquid elastic tensor, and the condition of exciting SH-APM in the piezoelectric plate by inter-digital transducers is researched. Choosing PZT-5H piezoelectric ceramic as substrate material, the numerical calculation is implemented and the SH-APM device is fabricated accordingly. Using different ratios of pure water and glycerol as liquid samples, the validity of liquid viscosity sensing by SH-APM is proved by the experimental results.