The electromechanical response of a self-excited MEMS Franklin oscillator

We present a self-excited MEMS Franklin oscillator, which responds in steady state vibrations when subjected to a sufficient dc voltage. The system is constructed from an electrostatically-floating rotor, which sequentially transfers charge between a source and drain electrodes. We present a comprehensive analysis of the electromechanical response of the system. Our analysis shows that current flows from the source to drain only when the rotor is in transition. Surprisingly, at contact of the rotor with either the source or the drain electrodes, there is no current in the system, and the charge transfer mechanism is essentially a recombination of opposite charges. This means that although we drive our system by 30 to 70 Volts, the contacts are essentially cold switching. Our experimental measurements of the dynamic response of the system are in good agreement with our model predictions.