Nonlinear mechanical springs for counteracting nonlinearities in gap-closing electrostatic actuators

We show that nonlinear elastic springs can be used to counteract the nonlinearity of electrostatic forces in gap-closing electrostatic actuators. We demonstrate this in two types of devices. In the first, we use a nonlinear spring to extend the stable range of the parallel-plates actuator, and to ensure that the response in this extended range is linear by design. In the second device, we use a nonlinear spring to ensure that beyond what would have been the pull-in point, voltage remains constant and independent of charge. In effect, this second device is a rechargeable mechanical battery.