Dynamics of noncontact rack-and-pinion device subject to thermal noise: Multiharmonic motion of the rack

We study miniaturized noncontact rack and pinion composed of a corrugated plate and a corrugated cylinder intermeshed via the lateral Casimir force. We assume that the rack position versus time is a periodic multi-harmonic signal. The axle of the pinion is subject to Casimir torque, frictional torque, load torque, and random Gaussian torque. A Fokker-Planck rather than Langevin description of the pinion dynamics allows us to explore a huge parameter space in a reasonable computational time. We show that even at the room temperature, the device acts as a mechanical rectifier: The pinion rotates with a nonzero average velocity and lifts up an external load. For typical values of parameters, we find that the pinion rotates with an average angular velocity ∼1−30Hz. The thermal noise may even facilitate the device operation.