Low-frequency piezoelectric energy harvesting prototype suitable for the MEMS implementation

A low-frequency piezoelectric energy harvester based on impact vibration assembled with a compliant driving beam and two rigid generating beams is presented. The ambient low frequency is up-converted to high resonant frequency by the periodic impact between the driving beam and the generating beams. The advantages of the harvester are: restricting the large displacement of the compliant driving beam, improving power density and being especially suitable for a compact MEMS approach. The 1.53 mW average power of the macroscale impact vibration harvester is achieved at 20.1 Hz under 0.4g acceleration. The power density is 93.2 μW/cm³, which is 6.8 times that of conventional counterpart (13.6 μW/cm³). The measured results demonstrate the potential of the device applied to portable and implantable electronics benefited from the MEMS batch-fabrication technology.