Magnetically Excited Piezoelectric Energy Harvester for Micropower Supply and Wakeup Applications

A miniaturized, magnetically actuated MEMS energy harvester with a high power density is presented. The device can be excited contactless and at low frequencies thanks to an efficient frequency-up conversion. These characteristics render the harvester suitable for various applications like a compact micropower supply in the sense of classical energy harvesting, but also as a near-zero power wakeup device and for energy transfer in inaccessible locations. Power output up to 100 µW in resonance is reported. Pulse-like excitation in the frequency-up conversion scheme yields open-circuit voltages of up to 4 V. A near-zero power wakeup for stand-alone systems like sensor nodes is demonstrated with a wakeup time of 20 ms and 0.1 nW power consumption when deactivated.