Enhancing Low-Velocity Water Flow Energy Harvesting of Triboelectric–Electromagnetic Generator via Biomimetic-Fin Strategy and Swing-Rotation Mechanism

A general problem is that the energy harvesting of low-velocity rivers closely related to human life is difficult. Herein, a soft-bionic-fin structure triboelectric–electromagnetic generator (SF-TEG) with swing-rotation mechanism is proposed. It consists of a bionic fin-type soft body and a power generation part including the triboelectric nanogenerator (TENG) and electromagnetic generator (EMG). Specifically, the soft body driven by the vortex effect acquires swing, which brings the TENG to obtain oscillation and then drives the EMG to realize water flow energy harvesting. The TENG and EMG attain the output voltages of 143 to 203 V and 4.6 to 7.7 V, respectively, under flow velocities from 0.34 to 0.96 m/s. The output voltages of the TENG and EMG retain about 98% and 100%, respectively, after 4 h of continuous work. Additionally, the SF-TEG can harvest water flow energy from open channels to power sensors to provide temperature, humidity, and light intensity for greenhouses.