A Geometrically Predetermined Eighth Order Nonlinear Flexure for Extending the Stable Travel Range of the Electrostatic Actuator

In this paper, we designed and fabricated a highly nonlinear suspension flexure with geometrically predetermined eighth order force-displacement relation for extension of the stable travel range of electrostatic actuator. Its strong nonlinearity is obtained by a rolling slide between a customized curved trajectory and a ball at the tip of the mandril. The customized nonlinear behavior can be adjusted and dominated by a geometrically predetermined trajectory. The experimental result illustrates that the restoring force of the fabricated nonlinear flexure is proportional to the eighth power of the electrode displacement approximately, and the stable travel of the electrostatic actuator with this flexure is extended to at least 63% of the nominal gap. The proposed scheme can also be implemented to other systems where the nonlinearity is needed, such as energy harvesting and the damper in the micro-scale.