Tiny Electric Motor, More Power Density.

According to a report published in the 21 March 2005 issue of Applied Physics Letters, the smallest electric motor in the world, devised by physicists at UC Berkeley, is based on the shuttling of atoms between two metal droplets---one large and one small--- residing on the back of a carbon nanotube.

An electric current transmitted through the nanotube causes atoms to move from the big to the small droplet. In effect, potential energy is being stored in the smaller droplet in the form of surface tension. Eventually the smaller drop grows so much that the two droplets tou