Influence of the Casimir force on the pull-in parameters of silicon based electrostatic torsional actuators

We perform a theoretical analysis focusing on the effect of the Casimir force (the result of the quantum fluctuations of the vacuum electromagnetic field) on the pull-in parameters of electrostatic torsional actuators (ETA) made from silicon. The Casimir force is calculated taking into account the frequency-dependent dielectric properties of silicon. We also address the role of surface roughness and temperature. Its is found that in spite of the weakening of this force with respect to the case of perfectly conducting parallel plates, the Casimir force considerably changes the pull-in parameters for devices with lateral dimensions in the range of a few tens of micrometers, actuator to substrate distance from 200 nm up to 1 μ m and low operating voltages compatible with, for example, CMOS technology.