High efficiency energy harvester of transferred epitaxial PZT films on stainless steel sheets

In this study, we fabricated high-efficiency piezoelectric energy harvesters composed of c-axis oriented PZT thin films. The PZT film was epitaxially grown on a Pt/MgO substrate and successively transferred on to a stainless steel sheet so as to prepare the unimorph cantilevers. Although the harvester had a simple cantilever structure without seismic mass, the resonant frequency could be reduced to 126 Hz due to the thin thickness of stainless sheet of 50 µm. When we applied the acceleration of 5 m/s2 on the harvester, it could generate large electric power of 5.3 µW at the resonant frequency. Transferred epitaxial PZT films on the metal sheets are effective not only to enhance the output power, but also to reduce the resonant frequency to around environmental vibration using the simple cantilevers.