Electrode shape dependence of the barbell-shaped magneto-mechano-electric energy harvester for low-frequency applications

A magneto-mechano-electric (MME) device for energy harvesting from ambient low-frequency magnetic field is investigated in this study. Consisting of piezoelectric ceramic rings, NdFeB permanent magnets and union piece, the proposed MME energy harvester is designed with the barbell-shaped structure operating in d₃₃ mode. NdFeB permanent magnets are attached at the free end of barbell-shaped structure, which can produce compressive stress on the piezoelectric ceramic rings via magnetic torque effect. The properties of the MME energy harvester are optimized by using the finite element analysis. Two electrode shapes, including full electrode and divided electrode, are investigated in the aspect of their influences on the device performance. The finite element analysis is consistent with the experimental results, revealing that the electrode shape of piezoelectric ceramic rings is crucial for the performance of the proposed MME device. The MME device presents a low resonant frequency (<50 Hz), a magnetoelectric coefficient higher than 1 V/cm Oe, a high output voltage (>10 V @ 10 Oe), a maximum output power of ˜10.5 μW and a maximum power density of 3.5 μW/Oe cm³, demonstrating the potential applications for harvesting ambient low-frequency magnetic field energy.