An innovative piezoelectric energy harvester using clamped-clamped beam with proof mass for WSN applications

In this paper a miniature piezoelectric energy harvester (PEH) with clamped-clamped beam and mass loading at the center is introduced which has more consistency against off-axis accelerations and more efficiency in comparison to other cantilever PEH's. The beams consist of different layers of Si, piezoelectric, and insulators based on MEMS technology that vibrates by applying an external force to the fixed frame. Due to beam vibration, variable stress is applied to the AlN piezoelectric and a potential difference is created at the output terminals. AlN is deposited on clamped-clamped beams in such a way that produce more stress points which cause more power to be generated in comparison to other cantilever beam PEH's with about same dimensions. A partial differential equations (PDE) describing the flexural wave propagating in the multi-morph clamped-clamped beam are solved as theoretical calculations for inherent frequency estimation and is confirmed by simulation results. The obtained inherent frequency is 42 Hz which with 1 g (g = 9.81 m/s(2)) acceleration produces 4 V and 80 mu W maximum electrical peak power that can be used in the node of low-power consumption wireless sensor node for wireless sensor network (WSN) applications.