The PZT/Ni unimorph magnetoelectric energy harvester for wireless sensing applications
The PZT/Ni unimorph cantilever with permanent Nd-magnet (NdFeB) as a tip mass is proposed for harvesting energy from the low frequency (50/60 Hz) and low amplitude magnetic field (≤10 Oe) for wireless sensing applications. The maximum power density of PZT/Ni unimorph cantilever is 270 µW/cm3 at a resonant frequency of 50 Hz (1 Oe), being one order of magnitude higher than a previously reported PZT/Cu cantilever energy harvester (11.73 μW/cm3), and comparable to an expensive PMN-PZT single crystal fiber/multi-layer FBS film cantilever energy harvester (333 μW/cm3). The acquired output power allows the energy harvester to turn on 100 commercial LEDs without a power storage unit. Both experiments and finite element analysis imply that the enhanced power density is due to the coupling of magnetostriction of the Ni beam and magnetic torque of the Nd-magnet. Together with a simple electric circuit, the PZT/Ni unimorph cantilever can successfully power a commercial wireless temperature/humidity sensor. The proposed ME energy harvester was demonstrated to scavenge ambient magnetic energy and a power wireless sensing system, exhibiting great potential for application in the IoT (internet of things).