Physicists build world's smallest motor using nanotubes and etched silicon <br /><br />This thing is pretty amazing: 500 nanometers across (about 300 times smaller than the diameter of a human hair), rotor between 100 and 300 nanometers long, carbon nanotube shaft between 5 and 10 nanometers thick.<br /><br />They expect to be able to reduce the size even further.