A multimodal and multidirectional frame-like piezoelectric energy harvester: A numerical and experimental study

An efficient vibration-based piezoelectric energy harvester (VPEH) is developed to address the need for broader frequency bandwidth, omnidirectional energy capture, and enhanced efficiency. Using COMSOL Multiphysics, a three-dimensional finite element model of a frame-like energy harvester (FEH) was developed and compared against a cantilever beam energy harvester (CBEH). For a reliable comparison, the CBEH and FEH were designed to have the same length, closely matched first natural frequencies, and total weight. The Multimodality Index (MMI) is defined in this study to investigate the multimodality of the designed harvesters. The so-called MMI and the modal analysis results indicated that the FEH excels in multidirectionality and multimodality aspects over the CBEH. Additionally, the electromechanical analysis showed that the FEH achieved an improved frequency bandwidth, covering the first four modes and yielding an average output power of 18.96 µW across a 10–200 Hz frequency range. The simulation results were validated through precise experiments, confirming that the developed FEH is a highly effective VPEH capable of multidirectional and multimodal energy harvesting with high power density and bandwidth.