Multi-directional and ultra-low frequency energy harvester utilizing tunable buckled piezoelectric film

Ultra-low frequency vibrations pose a particular challenge for vibration energy harvesters (VEH) due to their large wavelengths and low energy levels. Meanwhile, to enhance the overall energy harvesting efficiency, the VEH should have the potential to capture vibrations from different directions in various scenarios. In this study, a buckling piezoelectric energy harvester (BPEH) is designed for harvesting multi-direction and ultra-low frequency vibration power by incorporating piezoelectric materials into a controllably buckled film. The proposed model features two separate vibration modes in the low frequency region, and vibration excitation from diverse directions will concurrently excite these two vibration modes. In this work, theoretical analysis and finite element simulation are utilized to generate the analytical formulations for the output characteristics and optimization parameters of the model of BPEH. The result indicates a significant improvement in the BPEH's harvesting efficiency and an increase in power density of 1–2 orders of magnitude compared to the VEH of the cantilever beam configuration, and an increase of 5–8 times compared to the VEH of the single direction buckling configuration.