Most of the vibration sources, which could be used for energy harvesting, are vertical and very low frequency (e.g. human movement, vehicle transportation, etc. . . ). Under those conditions and while considering the size constraints, usual vibration energy harvesters (VEHs) underperform due to the combined effect of gravity, mechanical damping and the necessity to be tuned to very low frequencies. In order to overcome these limitations, the concept of High Static Low Dynamic (HSLD) stiffness is proposed and validated for VEHs. To do so, a theoretical study is performed to optimize the electromagnetic structure and design a folded-beam suspension of the moving mass allowing a low mechanical damping. This leads to the design of an original VEH, which is experimentally characterized under harmonic and white noise excitations. Compared to the literature, it demonstrated high performances with up to 41.3 mW cm −3 g −2 of normalized harvested power at an operating low frequency of 5.3 Hz.

Vibration Energy Harvesters (VEHs) are devices used to collect mechanical energy from the surrounding environment to supply low power electronic systems such as Wireless Sensor Nodes. In this paper, we introduce an electromagnetic VEH model and a semi-analytical method called Moment Equation Copula Closure (MECC) that is compared to Monte Carlo simulations. Those methods are then used to derive the maximum power that can be extracted from random vibration before analyzing the effect of cubic stiffness nonlinearity on the VEH robustness against the variation of the excitation spectrum. Unlike bistable nonlinearity, it is shown that Duffing nonlinearity can be used to enhance the VEH power density and robustness with a limited effect on the harvested power.