World's smallest motor is a techno marvel
A tiny motor, so small it could ride on the back of a virus, has been created by U.S. scientists in an achievement that will help advance the frontiers of nanotechnology.
It comprises a gold blade attached to an axle made from a carbon nanotube, whose ends are anchored to two silicon dioxide electrodes. Voltage flows through the electrodes and down the nanotube to rotate the blade.
Three other electrodes - two placed on either side of the axle, one underneath - provide additional voltage control, so that the speed of the blade, its direction and position can be governed precisely.
The arrangement, so tiny that it has been embedded in a silicon chip, is not the smallest nano-scale device in the world, a title that belongs to experimental 'bio-switches' made from molecular DNA and which are driven by chemicals.
But the rotor offers several advantages, said the researchers. As an electrical-mechanical device, it can tolerate wider temperature ranges, operate in a vacuum and cope with harsher chemical environments than its 'bio' equivalents.
Nanotechnology is an eagerly researched area because of the potential it offers for the next generation of miniaturised devices in communications, consumer products, medicine and a range of other fields.
Scientists working with electro-mechanical systems have been frustrated, for conventional metals and plastics can throw up unexpected performance problems when they are brought down to microscopic size.
This explains the surge in interest in carbon nanotubes - a new material comprising long, resilient chains of carbon atoms that conduct heat and electricity.
The new gadget is important because it proves that electro-mechanical devices can be made on such a small scale, and that simple and elegant sources can be used to drive them. Previous nanoscale motors needed help from large and cumbersome external sources, such as lasers and magnets, to operate.
The invention has several potential uses, said Dr Zettl: the blade could act as a switch in next-generation communications products, working as a rotating mirror for laser signals. It could also act as a tiny propeller to drive fluids, he said.