An energy harvester with nanoporous piezoelectric double-beam structure

Piezoelectric energy harvesters at nanoscale have been investigated recently in the demand of the miniaturization for the self-power electrical devices. In this paper, a pair of identical nano piezoelectric beams connected with springs and a storage circuit are modeled as an energy harvester. The pores are introduced to reduce the brittleness of the piezoelectric materials. Surface elasticity and Biot’s porous theory are applied to derive the governing equation and analytical solution of the model. The numerical results show that the double-beam harvester behaves much better than the single-beam one regarding the energy collection and resonant frequency range. The original length of the springs and the geometrical dimension of the beams have significant influence on the behavior of the harvester. The higher output power and lower resonant frequency can be achieved by attaching concentrated masses at the ends of the double beams. The output voltage and power depend on the surface piezoelectric constants and solid–fluid coupling piezoelectric parameters. The results are hopefully useful to provide guidance for designing and optimizing the nano energy harvesters.