Giant tridimensional power responses in a T-shaped magneto–mechano–electric energy harvester

Abstract

Magneto–mechano–electric (MME) energy harvester is a promising candidate for collecting weak vibration energy and also weak magnetic field energy from the ambient environment, and then using this to power wireless Internet of Things (IoT) systems. However, it is a tough task for the classical cantilevered MME energy harvesters (MME-EHs) to effectively capture ambient randomly-oriented magnetic field energy due to their unidirectional bending responses. To overcome this obstacle, this work presents a novel T-shaped MME-EH with symmetrically distributed magnet masses at two ends of its transverse beam that enables collaborative twisting or bending operation modes for tridimensional MME responses. Under a weak AC magnetic field excitation H_ac of 1.75 Oe, the T-shaped MME-EH operating in the in-phase bending mode could produce a maximum peak–peak output power of 98.5 mW (∼12.3 mW_RMS) at a resonance frequency of 60 Hz, which was 262% higher than the state-of-the-art results. The theoretical model of the T-shaped MME-EH revealed that the improved MME coupling and output performance originated from the optimized lumped parameters and the enhanced deflection gain. By harvesting the stray magnetic field from a home appliance, the T-shaped MME-EH realized could power an environmental monitoring module in real time. The collaborative modes, tridimensional responses, and effectively enhanced power performances demonstrated in this work can enlighten the future design of MME energy harvesters for efficiently harvesting extremely weak, randomly-oriented stray magnetic field energy.