Vortex-induced vibration triboelectric nanogenerator for energy harvesting from low-frequency water flow

The hydrokinetic energy from wind and water flow widely exists in nature. Even though previous studies have proposed various design architectures using both piezoelectric and triboelectric effects to capture the kinetic energy of the wind, they can hardly be applied into low-speed water environment. In this paper, we propose a vortex-induced vibration triboelectric nanogenerator (VIV-TENG) to scavenge energy from low-speed water. The VIV-TENG is mainly composed of a cylinder and a rail with two nanogenerators. The vortex is aroused by the cylinder and the vibration is amplified by the cantilever beam. We introduce a correction factor into the classical vortex-induced vibration coupling model to investigate the vortex shedding of the device. The finite element analysis is conducted to validate the theoretical model and is used to interpret the vortex resonance of the VIV-TENG. Besides, we experimentally demonstrate that the VIV-TENG achieves a maximum open-circuit voltage output of 174 V and a maximum power output of 2.5 mW at 1 MΩ in the condition of vortex resonance. The VIV-TENG also shows the ability to charge capacitors. This study provides a new approach for harvesting energy from low-speed water flow using the triboelectric effect.