Structural approaches for enhancing output power of piezoelectric polyvinylidene fluoride generator

Flexible piezoelectric generators have attracted considerable attention in recent years on account of their potential applications in mechanical energy scavenging devices using portable, wearable, and implantable electronics. Key issues for realizing a flexible piezoelectric generator include insufficient output power generation and poor efficiency at low frequency. We therefore propose structural approaches to enhancing the output power of the flexible piezoelectric generator using polyvinylidene fluoride. Specifically, we propose the use of a substrate and curved structure, and optimization of the aspect ratio of the generator for maximizing output power density. Through these approaches, induced stress and output voltage of the generator are analyzed by finite element modeling and validated through experiments. Considering these results for generator optimization, we fabricate a multilayered flexible curved generator, which produces ~200 V of the peak output voltage and ~2.7 mA of the peak output current. The output power density of the generator reaches ~17 mW/cm², which is sufficient to drive various commercial electronics as a power source. Furthermore, it is demonstrated that this power source can illuminate 952 LED bulbs. This conceptual technology can provide the groundwork to enhancing the output power of conventional piezoelectric generators, thereby enabling novel approaches to realizing self-powered systems.