Designing a piezoelectric device for elastic wave energy harvesting: An analytical approach

This study presents a comprehensive analytical approach to optimizing piezoelectric devices for elastic wave energy harvesting (EWEH). Unlike conventional vibration energy harvesting, EWEH lacks a defined resonance mechanism, necessitating an in-depth understanding of the interactions between device geometry, electroelastic coupling, and power generation. In this study, an electroelastically coupled analytical model is developed, based on S-parameter method, to derive closed-form solutions for reflection and transmission coefficients, as well as output voltage. The influence of geometric parameters, such as thickness and length, in conjunction with electrical resistance, on power output is the focal point of parametric studies. These studies yield practical design guidelines, including a method for determining power-optimal resistance from the perspective of effective mechanical impedance and a framework for selecting the optimal length and thickness from the perspective of tradeoff relationships among energy conversion efficiency and the amount of mechanical energy transferred to piezoelectric devices. Furthermore, compared to finite element models, the proposed analytical method offers superior computational efficiency, facilitating rapid design exploration and identification of power-optimal configurations. The findings of these parametric studies contribute to the systematic design of high-performance piezoelectric devices for efficient EWEH.