Jingxiong Wang, Bian Wu, Nan Shao, Xiaoqing Pu, Jiawen Xu, Ruqiang Yan
Harvesting energy from human motion presents an effective approach for enabling self-powered operation of low-power devices. This paper develops a multiple-layer piezoelectric energy harvester (PEH) with an annular stable (AS) two-dimensional potential well. The design involves two orthogonally arranged, double-layered piezoelectric composite cantilever beams coupled via repulsive magnetic forces. Facilitated by a nonlinear coupled internal resonance effect, an annual potential well is created, allowing for high-efficiency operation through annual-shaped inter-well modulation. The system can capture energy in multiple directional excitations from human motions. A mathematical model is derived, and theoretical analysis elucidates the operational mechanism of the AS-PEH. Numerical simulations and experimental studies validate the feasibility of the proposed harvester. The designed AS-PEH features large inter-well motion with small amplitude excitations. In particular, the AS-PEH demonstrates a 645 % wider operational bandwidth and a 144 % higher output voltage compared to that of a conventional bistable PEH structure (CB-PEH) under 0.5 g excitation. In addition, the proposed design features highly efficient vibration energy harvesting under two-dimensional excitations. A case study on human motion was carried out with a self-powered sensor for ECG monitoring. This annular stable, multiple-layer dual‑cantilever PEH introduces a novel design paradigm for nonlinear energy harvesters. By leveraging its inter‑well modulation mechanism, the proposed configuration achieves satisfactory performance in harvesting low‑frequency, low‑intensity, and multidirectional biomechanical energy from human motion.