Use of Angularity on Piezoelectric Crystal to Create Frequency Phase Shift for a Wide-Band Energy Harvester

Piezoelectric materials, when positioned angularly with respect to their crystallographic axis, exhibit a fascinating phenomenon: the creation of a frequency phase shift (FPS) during resonance. Traditionally, FPS arises due to changes in shape and material properties, causing the resonance frequency point to shift. However, present research has revealed an unexplored avenue: when a piezoelectric crystal vibrates along an axis that deviates from the normal poling axis, it manifests FPS phenomena. This unique behavior can be harnessed for a wide-bandwidth energy harvester—a novel application that has not been investigated by other researchers.

Rather than delving into the theoretical nature of FPS, this study focuses on practical implementation of this phenomenon. Clear mathematical assumptions, coupled with experimental validation, confirm the significant impact of angular position on piezoelectric crystals. Overall, 3 methods of mathematical modeling (with explicit formulas in the appendix), experimental setup and finite element method (FEM) have been used in this study.

The results from all the three methods for solving flexural motion demonstrate how power output depends on the angular position of the model and the dimensional variations of the beam and the piezoelectric material. The newly designed energy harvester produces 5 μWatt of power in both analytical and experimental approaches, under an acceleration of \(1 \, m{s}^{-2}\) $1m{s}^{-2}$ . Operating within a 20 Hz bandwidth for half-power level and utilizing two perpendicular beams, this design ensures that power output remains nonzero regardless of changes in the assembly’s direction of excitation.