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.