Yoyo-ball inspired triboelectric nanogenerators for harvesting biomechanical energy

The yoyo ball is a type of entertainment and fitness toy, that is popular worldwide. Herein, we propose a yoyo-ball-inspired triboelectric nanogenerator (YB-TENG) for biomechanical energy harvesting. The yoyo ball is designed as a rotor, and a string is wound on its inner diameter to form a novel two-in-one mechanism, which converts the periodic hand lifting energy into high-frequency rotation energy of the rotor. Two coaxial stators are installed on both sides of the rotor, and the friction layer and interdigital electrodes are pasted on the sides of the rotor and stator, respectively, to realize a free-standing mode TENG. Based on the fabricated YB-TENG prototype and dynamic model, the relationship between the output voltage waveform, frequency, and rotor speed is examined using time frequency analysis and numerical simulation. After the optimal load resistance is obtained, the effects of the friction layer material and structural parameters (including the number of electrode section pairs, gap length between the rotor and stator, and string length) on the YB-TENG output power are analyzed. By charging the load capacitors and effectively powering a series of LED lamps and micro-power devices, the YB-TENG exhibits potential as a portable energy source.