A spring-type piezoelectric energy harvester

Abstract

We developed a three-dimensional spring-type piezoelectric energy harvester using a dip-coating method and multi-directional electrode deposition. The energy harvester consists of a bi-layered structure composed of a surface electrode and a ferroelectric polymer, on a conventional spring which has two roles – the core electrode and the mechanical substrate for the ferroelectric polymer. The energy harvester generated an output voltage of up to 88 mV as a function of cycling compression stress, which leads to a piezoelectric constant of 28.55 pC N⁻¹ for unpoled P(VDF-TrFE) films. Since the spring structure significantly decreases the resonance frequency of the harvester, the spring-type energy harvester can effectively generate electricity using low-frequency vibration energy abundant in the nature.