Nonlinear Energy Harvesting Using Electromagnetic Transduction for Wide Bandwidth

We report the relative performances of monostable and bistable miniaturized electromagnetic energy harvesters (EMEHs) using micromachined fiberglass-epoxy spring structures. Monostable nonlinearity is realized in our device using the specially designed spring arms, whereas bistable nonlinearity is introduced through the interactions between repulsively oriented magnets. For devices of similar size, the monostable electromagnetic harvester generates larger output power compared to the bistable system under the same mechanical input. This is due to the additional damping provided by the strong bistable force, which also restricts the bandwidth widening of the bistable device compared to that of the monostable energy harvester. However, as the bistable force changes the linear stiffness of the system as well, the overall frequency response shifts toward the low-frequency region. Hence, low-frequency, wideband harvesting can be obtained in bistable devices compared to monostable devices of the same mechanical dimensions.