Energy Harvester

In recent years, piezoelectric energy harvesting from vibrations attracted much attention, also in the field of microsystems. The idea is to provide power to low-power circuits as present in wireless sensors. Devices based on AlN (parallel plate electrode) and PZT (interdigitated electrode) were developed. The advantage of AlN is nevertheless is low dielectric constant leading to a large voltage response. An increase in e31,f e.g. doping with Sc would be very beneficial. One could for instance avoid vacuum packaging in resonant harvesters. Important is, however, to make sure that the dielectric constant does not increase too much. The interdigitated PZT version perform in a similar high output voltage range, however, with a much larger electromechanical coupling coefficient. in other word, the new version can be used in combination with lower quality factor resonant structures. ­

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