A low-frequency vibration energy harvester employing self-biased magnetoelectric composite

Abstract

A prototype of vibration energy harvester is presented which mainly consists of a self-biased magnetoelectric (ME) composite, and a permanent magnetic cylinder which is connected to a spring (spring-magnet). The harvester shows its effectiveness in scavenging low frequency mechanical energies such as human motions. Upon a vibration signal with a displacement control of 3 cm and a frequency of 5 Hz, a peak-to-peak voltage of 2.65 V can be obtained. When hand shaking the prototype, a maximum peak-to-peak open circuit voltage of 2.52 V is induced. The output voltage is also tested when the prototype is worn on the waist, leg, and arm, under jumping, stepping or walking conditions. A maximum power of 14.44 μW is obtained for the prototype weighing 34.08 g at a vibration of 5 cm and 5 Hz across a 10 kΩ load. Finite element simulations are performed to reveal the vibration modes and the corresponding values of output voltage. Comparison between the experimental data and the calculation results helps to better understand the displacement of the harvester under the vibrations and its effects on the output voltage. The energy harvester holds promises for a powering miniaturized or portable devices.