Stochastic resonance in a voltage-controlled micromechanical slider

Stochastic resonance (SR) is a phenomenon that has been extensively investigated theoretically, but which is much harder to study experimentally. In this paper, we report on an experimental micromechanical slider structure that allows for full control of most of the parameters that are of importance for the occurrence of SR. Using a silicon-on-insulator-based process, we realized a slider structure with periodic capacitive structures to obtain tunable unstable regions. We implemented stochastic resonance by controlling the strength of these capacitive wells by a dc-bias voltage, operating the device in push-pull mode by electrostatic actuation, and adding a judiciously amount of white noise to the actuation comb drives. It is shown that this SR scheme allows for detection of subthreshold forces. We find that the amount of noise needed for optimal SR depends strongly on the noise bandwidth. Further, we demonstrate that the imple- mentation of SR in a slider allows for improved detection of both sinusoidal and triangular waveforms, but that the performance of SR deteriorates for square waveforms.