The piezoelectric vibration energy harvester can collect energy from the ambient vibration. The vibrations from the environment are usually random and also from various directions. The current energy harvester cannot efficiently collect the energy from vibration and also the energy transfer efficiency is very low, and the bandwidth is limited. Therefore, this paper proposed a novel cross-coupled L-shaped piezoelectric vibration energy harvester (CL-PVEH) to solve the low efficiency and narrow bandwidth. This structure consists of a vertical beam and a horizontal beam joint crosswise to complete a multi-directional energy harvester. The finite element analysis (FEA) and analytical study are performed in comparison that the ability of energy conversion efficiency for the cross-coupled and traditional L-shaped structures. The results demonstrate that the CL-PVEH can harness energy effectively under excitations from three perpendicular directions while the TL-PVEH can harness energy under excitation from only two directions effectively. Meanwhile, the CL-PVEH can generate three output peaks under a frequency range of 10Hz–100Hz, which are 18.8Hz, 24.8Hz, and 91.5Hz under multi-directional excitations. The multiple natural resonance frequencies under different direction excitations display that the CL-PVEH has a great ability of broadband energy harvesting and can be more flexible in mechanical structure health and human health status monitoring, especially in complex and multi-directional vibrational environment.

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