Segmentation of piezoelectric layers based on the numerical study of normal strain distributions in bimorph cantilevers vibrating in the second transverse mode

摘要

Nowadays energy harvesting is becoming an increasingly important issue for low-power micro-systems (for e.g. wireless node systems, seismic sensors, etc.). Progress in modern ultra-low-power microelectronics demand a promote progress in micro-energy harvesting from ambient energy sources to create self-powered microsystems. Since usual locations for such systems are hardly accessible it is natural that it is required that these sensors or systems would be self-powered, would satisfy certain size and mass requirements, and would assure continuous, longterm, uninterrupted power supply without replacement of batteries or other elements. Several ambient energy sources could be harnessed for this purpose such as thermal gradients, photonic energy, various forms of radiation though the biggest potential is seen in mechanical energy and vibrational energy in particular since low and medium frequency vibrations are all around us and may offer a constant and reliable power supply if harnessed correctly. During recent years energy harvesting from vibration sources has attracted a lot of interest, particularly as micro energy sources. The main application for these are wireless sensor nodes, communication modules, etc. Supply powers of < 100 μW are sufficient to operate wireless nodes in silent mode. The duty cycle can be quite small so that mW supply levels already enable some autonomy. Motion and vibrations are the most versatile and ubiquitous ambient energy source available [1]. The mechanical to electrical energy transformation is most efficiently done by piezoelectric materials [2].