Wide-bandwidth triboelectric energy harvester combining impact nonlinearity and multi-resonance method

This paper presents a novel wide-bandwidth triboelectric energy harvester (WBTEH) that takes advantage of impact nonlinearity and multi-resonance. The harvester features a triboelectric transducer that operates in contact and separation mode, with two cantilever beams of different resonant frequencies connected to it. By exploiting the relative motion of the beams, the harvester achieves a broad bandwidth through the resonance shift caused by the impact and multi-resonance. A WBTEH prototype with a 3 mm gap between the triboelectric pair shows a total bandwidth of 4.3 Hz even at a low base excitation of 3 m/s2. The matched peaks and bandwidth in the frequency up-sweep and down-sweep tests demonstrate the excellent stability of the WBTEH. The frequency locking phenomenon with strong resonance occurs in the WBTEH when the displacement amplitude/gap ratio exceeds 1.48, which is beneficial for obtaining a continuous bandwidth and a high power output. An electromechanical model is formulated for parametric studies that investigate the effects of contact stiffness and damping on the performance of WBTEH. It is found that large impact stiffness and small damping can cause quasi-periodic motion, leading to a non-constant voltage output that should be prevented in the harvester design. The WBTEH is capable of powering wireless sensors, making it a potential candidate for Internet of Things (IoT) applications.