Harvesting vibration energy by novel piezoelectric structure with arc-shaped branches

In this study, we proposed a novel energy harvester that consists of a piezoelectric inverted beam and two arc-shaped branches. The harvester owns the characteristics of super-harmonic and subharmonic vibrations, so its working frequency bandwidth can be significantly extended. Then, for broadband excitation, the harvester can keep a fairly large electric output. The theoretical model is established at first, and the simulations for frequency-sweeping and harmonic excitations are carried out. The results show that there exist the super-harmonic and sub-harmonic vibrations in response. Then, the validation experiments are conducted, and the results prove the theoretical analyses. Furthermore, in the experiments there occurs the transition from the synchronization vibration to sub-harmonic resonance, which results in a dramatic increase in amplitude and output. Finally, the experiment for stochastic excitation is carried out. The results show the harvester could give a large electric output under weak stochastic excitations. For the excitation of PSD = 0.07 g2/Hz, the output power can reach 21.2 & mu;W.