Flexoelectric Energy Harvesting Using Circular Thin Membranes

In this work, we propose a circular membrane-based flexoelectric energy harvester. Different from previously reported nanobeams based flexoelectric energy harvesters, for the flexoelectric membrane, the polarization direction around its center is opposite in sign to that far away from the center. To avoid the cancelation of the electric output, electrodes coated to upper and lower surfaces of the flexoelectric membrane are respectively divided into two parts according to the sign of bending curvatures. Based on Hamilton’s principle and Ohm’s law, we obtain governing equations for the circular membrane-based flexoelectric energy harvester. A generalized assumed-modes method is employed for solving the system, so that the performance of the flexoelectric energy harvester can be studied in detail. We analyze the effects of the thickness h, radius r₀, and their ratio on the energy harvesting performance. Specifically, we show that, by selecting appropriate h and r₀, it is possible to design an energy harvester with both high energy conversion efficiency and low working frequency. At last, through numerical simulations, we further study the optimization ratio for which the electrodes should be divided.