Magnetic-linkage nonlinear piezoelectric energy harvester with time-varying potential wells: Theoretical and experimental investigations

Energy harvesting has emerged as a prospective solution for powering wireless sensors on the Internet of Things (IoT). However, the limited energy conversion efficiency remains a significant challenge, thereby hindering the feasibility of self-powered sensing in IoT. To address this issue, this paper proposes a magnetic-linkage nonlinear piezoelectric energy harvester (PEH) capable of effectively operating over a wide frequency bandwidth, particularly under low-level base excitations. The proposed PEH comprises one vertical and two horizontal piezoelectric beams, which are coupled by the magnetic force to realize the magnetic-linkage effect and create time-varying potential wells. A comprehensive theoretical model has been developed to reveal the working mechanisms of the magnetic-linkage effect and corresponding time-varying potential wells. Based on these foundations, theoretical results indicate that the magnetic configuration parameters have a significant impact on the magnetic-linkage effect and potential barriers. In addition, experimental investigations indicate that the magnetic-linkage effect broadens the effective frequency bandwidth, leading to a significant improvement in energy harvesting efficiency of up to 400% compared to the PEH without magnetic-linkage effect. Furthermore, the proposed PEH enables the realization of self-powered sensing in experiments. In summary, by exploiting the magnetic-linkage effect to create the time-varying potential wells, this innovative approach holds a great promising application for achieving high-efficiency energy harvesting from low-level environmental vibrations.