Exploiting the principle parametric resonance of an electric oscillator for vibratory energy harvesting

Vibratory energy harvesters typically exploit ordinary direct resonances to mechanically amplify environmental inputs before channeling a portion of their energy into an electric load using an electromechanical transduction mechanism. Nonetheless, parametric resonance which has also been recently exploited, but to a lesser extent, holds a key advantage over direct excitations in that, when the level of input excitation exceeds a certain threshold, the amplitude of growth associated with parametric pumping is not limited by the total linear damping present in the system. While all of the previous research studies using parametric resonances for energy harvesting focused on utilizing it as a means of mechanical amplification, this letter demonstrates that vibratory excitations can also be used effectively to induce parametric resonances in the harvesting circuit itself, thereby providing a direct and simple means of electric amplification. A vibratory energy harvester exploiting this phenomenon is proposed in this letter and is shown to produce a maximum of 18 mW root-mean-square power per 1 g of input acceleration.