MEMS Power Receiver using Piezoelectric Cantilever Beams and Interdigitated Electrodes

Over the years, there has been a growing interest in the field of power transmission technologies for low-power electronic devices, such as wireless sensor networks and biomedical sensor applications. Among all possible energy sources, the mechanical vibrations have been considered as a potential choice for power transmission in a wide variety of applications. This paper presents the development of a piezoelectric MEMS transducer which has the ability to receive mechanical energy of ambient vibrations from an external generator and transform it into electrical energy that can be used in energy storage applications. The piezoelectric MEMS transducer comprises of a beam structure based on the silicon wafer and a pair of interdigitated electrodes placed in between the lead zirconate titanate (Pb(Zr,Ti)O₃, PZT) material and the beam structure. This transducer transforms mechanical strain energy into electrical charge with the d₃₃ mode of PZT. An optional proof mass can be built at the tip of the beam to adjust the structure resonant frequency of the transducer for most adaptable frequency matching to the various vibration generators. A theoretical model is also presented to investigate the relations between the charge generation ability and the design parameters of the transducer. To optimize the fabrication, a customized PZT deposition chamber which could deposit PZT thin film up to tens micron in minutes was used to deposit the piezoelectric layer on the beam structure.