Modeling and Characterization of Piezoelectric $d_{33}$ -Mode MEMS Energy Harvester

This paper presents the modeling, fabrication, and characterization of a piezoelectric microelectromechanical systems (MEMS) energy harvester using a d₃₃ piezoelectric mode. A theoretical analysis and an analytical modeling for the d₃₃-mode device were first performed to estimate the output power as a function of the material parameters and device geometry. A PbTiO₃ seed layer was newly applied as an interlayer between the ZrO₂ and Pb(Zr_0.52Ti_0.48)O₃ (PZT) thin films to improve the piezoelectric property of the sol-gel spin-coated PZT thin film. The fabricated cantilever PZT film with an interdigital shaped electrode exhibited a remnant polarization of 18.5 C/cm², a coercive field of less than 60 kV/cm, a relative dielectric constant of 1125.1, and a d₃₃ piezoelectric constant of 50 pC/N. The fabricated energy-harvesting device generated an electrical power of 1.1 W for a load of 2.2 M with 4.4 V_peak-to-peak from a vibration with an acceleration of 0.39 g at its resonant frequency of 528 Hz. The corresponding power density was 7.3 mW cm^-3 · g^-2. The experimental results were compared with those numerically calculated using the equations derived from the dynamic and analytical modeling. The fabricated device was also compared with other piezoelectric MEMS energy-harvesting devices.