Theoretical evaluation of asynchronous ac dielectric nanomotors

A design for an electric nanomotor driven by ac electric fields is presented and evaluated. The motor induces torque by means of a rotating electric field, which induces a dipole in the rotor; the interactions between field and dipole are responsible for both the generation of torque and the repulsion of the rotor, which stabilizes its position without contact and removes the need for bearings. The applied electric field is generated by square-wave pulses, allowing the direct computer control of the device without any digital-to-analogue requirement; the amount of torque generated can be controlled precisely by varying the number of clock cycles between digital state changes. The technology is scaleable, and a motor consisting of a rotor 1μm long and 100 nm diameter is shown to be capable of generating approximately 10^-15 N m^-1, equivalent to a bacterial flagellar motor.