Optimization of cantilevered piezoelectric energy harvester with a fixed resonance frequency

Piezoelectric energy harvesting is widely used to scavenge vibration energy in the environment. For some vibration sources with fixed frequency, cantilevered harvester can generate the energy effectively, so the optimization theory for cantilevered harvester in such an application is needed. In this article, we present the theoretical and experimental studies of the cantilevered piezoelectric energy harvester with a fixed resonance frequency. An analytical model based on energy method is used to estimate the open-circuit voltage and generated energy. Considering that the harvester may be subjected to the static force or steady-state sinusoidal vibration excitation, static and dynamic analysis is performed for device structure to achieve efficient energy. In the analysis, the effects of geometrical dimension on the energy harvesting performance are discussed comprehensively. Eventually, a prototype is designed and fabricated using (1-x)Pb(Mg1/3Nb2/3)O3-x PbTiO3 (PMN-PT) single crystal with ultrahigh piezoelectric properties and coupling factor. Performances of the cantilever with different clamped length are evaluated under sinusoidal vibration excitation, proving the good consistency between experimental results and theoretical prediction. The established analysis can provide useful guidelines for the structure design of cantilevered piezoelectric energy harvester with a fixed resonance frequency.