Optimization of piezoelectric receivers for acoustic wireless power transfer applications

Wireless power transfer is the key to achieve autonomous devices, and so far, the inductive approach has caught most of the attention. However, this technology cannot be employed with metallic walls, and the transmission distances are small. Alternatively, wireless power transfer with acoustic waves has the potential to overcome these limitations, and it could be used, for example, in the chemical industry to power sensors installed in pipes or to recharge batteries of medical implants located deep in the body. The present work aims to optimize the power transmission with acoustic waves by looking into the inner physics of this technology and of its piezoelectric acoustic power receivers in particular. To do so, an analytic model is first derived and the expressions of the optimal electric loads at the receiver are obtained. The model and the loads are then theoretically and experimentally validated. Finally, the analytic efficiency expressions are derived, and the key variables that influence the performance of the piezoelectric receivers are identified.