Springless cubic harvester for converting three dimensional vibration energy

This paper reports the design, fabrication and measurement of a springless cubic energy harvester. Based on the flexible printed circuits, coils are fabricated onto both sides of the polyimide substrate and then folded to a cubic box, meanwhile sealed a free magnet inside the box. As the coils are folded on three different directions, vibration in all dimensions can cause the change of magnetic flux and the energy is effectively harvested. Output performance of the device is both theoretically and experimentally investigated. Benefit from the springless structure, maximum output is achieved at low frequencies with a wide bandwidth. Moreover, the device can be placed on a backpack or wrist to harvest vibration energy from daily life.