Low‐frequency nanocomposite piezoelectric energy harvester with embedded zinc oxide nanowires

Abstract Sweeping developments in microelectromechanical systems and low power electronics have pushed the need for piezoelectric energy harvesters (PEHs). Increasing environmental and biocompatibility issues have drawn interest in lead‐free piezoelectric materials. In this paper, cantilever‐type PEHs at centimeter scale have been proposed to harvest the energies of low‐frequency vibrations caused by a human's movements. The proposed PEHs are made of a passive PDMS substrate sandwiched between two active nanocomposite layers with embedded piezoelectric zinc oxide (ZnO) nanowires. Moreover, two different morphologies including PEHs with constant and tapered thicknesses have been considered. The material properties of such piezoelectric nanocomposites are calculated by an electromechanical model. Afterward, these novel PEHs have been developed in COMSOL Multiphysics and their static and dynamic performances have been investigated. The static study shows that tapered PEHs endures lower stresses. However, the dynamic study discloses that the rectangular design outperforms the tapered one in electrical power and resonance frequency. It is found that the rectangular design can produce 4.1623 μW at the resonant frequency of 25.8 Hz.