A Double-Sided Comb-Drive Actuator with a Floating Rotor: Achieving a Strong Response while Eliminating the DC Bias

We present a novel way of using a double-sided comb-drive resonator, by disconnecting the rotor from any dc bias, and leaving it electrostatically floating. To demonstrate this, we first characterize the response of the resonator when the rotor is subjected to a dc bias, and demonstrate that as is widely known, increasing the dc bias on the rotor increases the resonator response to a small ac input signal. Then we demonstrate that even when the rotor is disconnected from any dc bias voltage, and it is left electrostatically floating, the resonator still responds to the input signal, and this response is considerably large. The explanation for this surprising phenomenon is that by disconnecting the rotor and keeping it electrostatically floating, we turn the common resonator into a parametric resonator. When the system is thus configured, small ac signals that drive the system are sufficient to produce a large amplitude of harmonic response, without requiring any dc bias. To validate the parametric response, we demonstrate that the system can be driven to resonance, by driving it at unit-fractions of the fundamental frequency. The relevance of this work is that it demonstrates that electrostatic resonators can be operated without requiring any dc bias. This may be beneficial for low-power sensors necessary for IoT technology. [2020-0066].