The realization and performance of vibration energy harvesting MEMS devices based on anepitaxial piezoelectric thin film

Abstract

This paper focuses on the fabrication and evaluation ofvibration energy harvesting devices by utilizing an epitaxialPb(Zr0.2Ti0.8)O3 (PZT) thin film. Thehigh quality of the c-axis oriented PZT layer results in a high piezoelectric coefficient and a low dielectricconstant, which are key parameters for realizing high performance piezoelectric energyharvesters. Different cantilever structures, with and without a Si proof mass, are realizedusing micro-patterning techniques optimized for the epitaxial oxide layers, to maintain thepiezoelectric properties throughout the process. The characteristics and the energyharvesting performances of the fabricated devices are experimentally investigatedand compared against analytical calculations. The optimized device based on a0.5 µm thick epitaxial PZT film, a cantilever beam of1 mm × 2.5 mm × 0.015 mm, with a Siproof mass of 1 mm × 0.5 mm × 0.23 mm, generates an output power, current and voltage of, respectively,13 µW g − 2,48 µA g − 1 and0.27 V g − 1 (g = 9.81 m s − 2) at the resonant frequency of 2.3 kHz for an optimal resistive load of5.6 kΩ. The epitaxial PZT harvester exhibits higher power and current with usable voltage,while maintaining lower optimal resistive load as compared with other examplespresent in the literature. These results indicate the potential of epitaxial PZTthin films for the improvement of the performances of energy harvesting devices.