Dual-Tube Helmholtz Resonator-Based Triboelectric Nanogenerator for Highly Efficient Harvesting of Acoustic Energy

An acoustic wave is a type of energy that is clean and abundant but almost totally unused because of its very low density. This study investigates a novel dual-tube Helmholtz resonator-based triboelectric nanogenerator (HR-TENG) for highly efficient harvesting of acoustic energy. This HR-TENG is composed of a Helmholtz resonant cavity, a metal film with evenly distributed acoustic holes, and a dielectric soft film with one side ink-printed for electrode. Effects of resonant cavity structure, acoustic conditions, and film tension on the HR-TENG performance are investigated systematically. By coupling the mechanisms of triboelectric nanogenerator and acoustic propagation, a theoretical guideline is provided for improving energy output and broadening the frequency band. Specifically, the present HR-TENG generates the maximum acoustic sensitivity per unit area of 1.23 VPa(-1)cm(-2) and the maximum power density per unit sound pressure of 1.82 WPa(-1)m(-2), which are higher than the best results from the literature by 60 and 20%, respectively. In addition, the HR-TENG may also serve as a self-powered acoustic sensor.