Nonlinear oscillation for a millimeter-sized electrostatic energy harvester.

This paper describes a demonstration of power enhancement by nonlinear oscillation in a millimeter-sized electrostatic vibrational energy harvester for the future Internet of Things. To attain nonlinearity in the microelectromechanical-system (MEMS) device, a gold spring, which has a lower value of Young's modulus than conventional materials, is adopted as a component of the MEMS structure. The nonlinear oscillation for the millimeter-sized ethylene tetrafluoroethylene (ETFE) electret energy harvester was confirmed experimentally by applying external vibration. The normalized harvester's effectiveness for the nonlinear oscillation is 9.6 times higher than that for the linear one.