Improve harvesting efficiency of tri-stable energy harvester by tailoring potential energy

In vibration energy harvesting, it has been proved that the tri-stable energy harvester (TEH) could give a large output through snap-through motion. But unfortunately, if it is under a weak excitation, the snap-through motion hardly occurs, due to the relatively high potential barrier. To overcome this defect, we introduce an additional magnet to TEH to tailor the potential energy, and then developed an improved tri-stable energy harvester (ITEH), which can realize snap-through motion easily. The electromechanical equations are derived, and the potential energy is given. The analysis shows that the additional magnet could elevate the bottom of potential well and lower the barrier between them, thereby making the snap-through motion happen more easily. Compared to TEH, the ITEH could begin snap-through motion from the weak excitation and generate a larger output voltage. The prototype of ITEH was fabricated, and the validation experiments were carried out. The experimental results are consistent with the theoretical predictions and prove the advantage of ITEH.