A Flexible Rolling Triboelectric Nanogenerator with a Bionic Gill Cover Structure for Low-Velocity Water Flow Energy Harvesting.

Harvesting low-velocity water flow energy stably over the long term is a significant challenge. Herein, a flexible rolling triboelectric nanogenerator with a bionic gill cover structure (GFR-TENG) to harvest steady low-velocity water flow energy is proposed. The dielectric material of the GFR-TENG is eight flexible hollow fluorinated ethylene propylene (FEP) pipes, which guarantees that rolling friction is formed between the dielectric material and copper electrode. This design significantly reduces wear between the dielectric material and copper electrode and enhances the durability of the triboelectric nanogenerator. Even after 1 700 000 cycles, its performance retention rate is more than 95%. The GFR-TENG using the wheel with bionic whale shark gill cover structure exhibits outstanding hydrodynamic performance, increasing by 24.54% comparing the normal wheel on the rotation frequency. In the research of water parameters, the GFR-TENG can steadily harvest water flow energy at a low-velocity water flow of 0.22 m s-1. Meanwhile, the GFR-TENG can all exhibit outstanding performance at different immersion depths. Finally, a wireless temperature sensor and a wireless light sensor are each powered by the GFR-TENG, which harvests energy from water flow in a natural open channel. The GFR-TENG provides a novel solution method for harvesting low-velocity water flow energy.