Design, simulation, fabrication and characterization of a micro electromagnetic vibration energy harvester with sandwiched structure and air channel

This paper presents the design, simulation, fabrication and characterization of a novel electromagnetic vibration energy harvester with sandwiched structure and air channel. It mainly consists of a top coil, a bottom coil, an NdFeB permanent magnet and a nickel planar spring integrated with silicon frame. The prototype is fabricated mainly using silicon micromachining and microelectroplating techniques. The tested natural frequency of the magnet–spring system is 228.2 Hz. The comparison between the simulation and the tested results of the natural frequency shows that the Young's modulus of microelectroplated Ni film is about 163 GPa rather than 210 GPa of bulk Ni material. Experimental results indicate that the sandwiched structure and the air channel in the silicon frame of the prototype can make the induced voltage increase to 42%. The resonant frequency of the prototype at 8 m/s2 acceleration is 280.1 Hz, which results from the nonlinear behavior of the magnet–spring system. The load voltage generated by the prototype is 162.5 mV when the prototype is at resonance and the input vibration acceleration is 8 m/s2 and the maximal load power obtained is about 21.2 μW when the load resistance is 81 Ω.