Vibration energy harvester with low resonant frequency based on flexible coil and liquid spring

This paper reports an electromagnetic vibration-energy harvester with lowresonant frequency based onliquid spring composed offerrofluid. Cylindermagnet array formed by four disc NdFeBmagnets is suspended byferrofluid in a laser-machined acrylic tube which is wrapped by flexible planarcoil fabricated with microfabrication process. Themagnet array andcoil are aligned automatically by theferrofluid. Restoring force when themagnet array is deviated from the balance position is proportional to the deviated distance, which makes theferrofluid work as aliquid spring obeying Hook's law. Experimental results show that the electromagnetic energy harvester occupying 1.8  cc and weighing 5 g has aresonant frequency of 16  Hz and generates an induced electromotive force of Vrms = 2.58 mV (delivering 79 nW power into matched load of 21 Ω) from 3 g acceleration at 16 Hz.

Source: Applied Physics Letters - November 14, 2016 Category: Physics Authors: Y. Wang, Q. Zhang, L. Zhao, Y. Tang, A. Shkel and E. S. Kim Source Type: research