• Energy Research

In this work, we demonstrate the simple fabrication process of AlN-based piezoelectric energy harvesters (PEH), which are made of cantilevers consisting of a multilayer ion beam-assisted deposition. The preferentially (001) orientated AlN thin films possess exceptionally high piezoelectric coefficients d33 of (7.33 ± 0.08) pC∙N−1. The fabrication of PEH was completed using just three lithography steps, conventional silicon substrate with full control of the cantilever thickness, in addition to the thickness of the proof mass. As the AlN deposition was conducted at a temperature of ≈330 °C, the process can be implemented into standard complementary metal oxide semiconductor (CMOS) technology, as well as the CMOS wafer post-processing. The PEH cantilever deflection and efficiency were characterized using both laser interferometry, and a vibration shaker, respectively. This technology could become a core feature for future CMOS-based energy harvesters.

AbstractThe micro-electro-mechanical array for application as fully implantable cochlea is presented in this paper. The complete system including a short overview of energy harvesting and the system configuration is proposed. This study mainly covers mechanical properties of cochlea microfabricated silicon structure. Electro-mechanical simulations are proceeded to optimize the material used for resonators, the size of array membranes and to estimate the resistive change due to the input sound signal. The sound is detected by thin SiXNY diaphragm due to resonant frequency and the displacement of the membrane caused by acoustic pressure. The displacement is detected employing piezoresistive electrodes (NiCr). Design and fabrication process based on MEMS technology are described and discussed. The response measurement of the cochlea structure is performed. The sizes of the membranes vary from (0.5×0.5) mm to (2.0×2.0) mm and the average current change is 6.55·10-3c% corresponding to the acoustic pressure of 0.01 Pa.