Silicon dioxide
Based on the plasmonic concept, Liu and coworker demonstrated the plasmonic motor at nanoscale. The gammadion-shaped nanostructures were made up of Gold (size ~ 190x 190 nm) which were symmetrically sandwiched between two Silicon dioxide layers. The whole system was fabricated by using standard electron beam lithography. When the system is illuminated with linearly polarized light, it produces a torque which drives these tiny nanostructures, called "plasmonic nanomotors". The imposed torque results solely from the gammadion structure’s symmetry and interaction with the incident light. These nanomotors seems to change their directions of motions (clockwise and anticlockwise) according to the wavelength (longer and shorter) of the incident laser beam.