Design and characteristic analysis of a novel flexible rod-based multi-directional piezoelectric vibration energy harvester

The piezoelectric vibration energy harvesters (PVEHs) are promising for powering wireless sensors in vibration environments. Conventional PVEHs show limited directionality and low reliability—simple geometry enables single-axis harvesting only, and bidirectional lead zirconate titanate [Pb(Zr,Ti)O3] (PZT) vibrator deformation introduces tensile fatigue, reducing operational lifetime. To overcome these limitations, this paper proposes a flexible rod-based multi-directional piezoelectric vibration energy harvester (MPVEH), which integrates a multi-directional excitation device with a combination transducer through magnetic coupling. The multi-directional excitation device, consisting of a flexible rod and a magnetic ring, enables energy harvesting from various planar directions, while the combination transducer ensures that the PZT vibrator operates under unidirectional compressive stress only, thereby enhancing reliability. Unlike conventional cantilever-based designs, the proposed MPVEH employs magnetic coupling to regulate vibration transmission within the structure, enabling enhanced planar directional adaptability while ensuring that the PZT vibrators operate under unidirectional compressive stress. matlab numerical simulations and comsol finite element simulations are conducted to analyze the magnetic coupling and vibration characteristics. Experimental tests are performed to evaluate the MPVEH’s performance under different excitation angles and longitudinal coupling distances. The results show that the MPVEH significantly broadens the effective bandwidth and improves directional adaptability, achieving a maximum output power of 4.8 mW at 14 Hz with an optimal load resistance of 350 kΩ. Furthermore, the MPVEH successfully powers 100 LEDs in parallel, demonstrating its potential for practical low-power applications. This study provides a viable structural solution for enhancing the environmental adaptability and reliability of PVEHs in planar multi-directional vibration scenarios.