Enhancing bandwidth of triboelectric vibration energy harvesters through magnetic tuning

This paper presents a novel design approach for ultra-wideband triboelectric vibration energy harvesters (UWBTVEH) by utilizing magnetic interactions to enhance performance. The triboelectric transducer operates through the coupled effect of two triboelectric layers, with nonlinear hardening and softening behaviors precisely controlled using both attractive and repulsive magnetic forces. This mechanism enables easy adjustment of beam resonances, resulting in a significantly broadened bandwidth. The approach is validated with a cost-effective UWBTVEH prototype comprising two cantilever beams, middle plates, magnet pairs and triboelectric transducers operating in a contact-separation mode. Nonlinear magnetic forces acting on the beams further influence the dynamic behavior of the triboelectric layers. Theoretical and experimental analyses demonstrate that the harvester, equipped with top and bottom magnet pairs at a 14 mm gap distance, achieves a bandwidth of 11.7 Hz under a base acceleration of 0.6 g. This performance marks a 72 % increase in the bandwidth compared to conventional triboelectric energy harvesters without magnet tuning under the same conditions. An electro-mechanical model was established and validated through experiments, demonstrating that the model effectively captures the key features of the harvester, including its wideband behavior, voltage output magnitude and asymmetric voltage signal. Furthermore, the energy generation capability of the UWBTVEH was demonstrated by powering an IoT sensing module, enabling wireless signal transmission. In summary, the proposed methodology offers valuable guidance for designing UWBTVEHs, making it particularly significant in applications involving variable-frequency energy sources.