Aspect ratio-dependent dynamics of piezoelectric transducers in wireless acoustic power transfer

Acoustic power transfer (APT) for wireless electronic components has received growing attention as a viable approach to deliver power to remotely located small electronic devices. The design of an efficient APT system requires accurate models to describe its individual components as well as the interaction between them. Most of the analytical models available to represent the bulk piezoelectric transducers used in APT are limited to either thin rod or thin plate transducers. However, transducers with moderate aspect ratios are often used especially at the receiver end. In this work, in addition to reviewing standard theories, models based on the Rayleigh and Bishop rod theories are developed to analyze transducers (transmitter or receiver) with various aspect ratios. Results from these models are compared with experimental data and finite-element analysis to determine the range of aspect ratios in which they are valid. In addition, fluid loading effects on the predictions of all models are investigated, and the generated pressure fields by the transducers with different aspect ratios are compared. The resulting models are used to analyze the effect of aspect ratio on the performance of the transducer when operated as a transmitter or a receiver in an APT setting.