A low frequency and broadband piezoelectric energy harvester using asymmetrically serials connected double clamped-clamped beams

A novel structure of piezoelectric energy harvester was developed using double clamped–clamped beams serials connected by a rectangular frame, coupled with a proof mass and supporting mass near the center of upper and lower beams. The serials connection has a significant effect on reducing the resonance frequency, which is predicted by theoretical analysis and validated by experimental, and a reduction of 36.7% is achieved compared with the single clamped–clamped beam. More importantly, the bandwidth of the power spectrum is 36.4% wider, by introducing an asymmetry of 1 mm between the proof and supporting mass, than that of the symmetric setup. More than 0.8 mW ranging from 144 to 170 Hz is obtained near the two peaks of 0.992 mW at 150 Hz and 0.844 mW at 165 Hz, respectively. For its lower frequency, broader bandwidth and compact volume, the asymmetric harvester has promising application in wireless sensors networks.