US physicists create World's smallest synthetic motor
By Mike Hanlon
July 26, 2003
Sunday July 27, 2003
In a significant breakthrough for what promises to be one of the key technologies in the 21st century, scientists at the University of California, Berkeley, have built the first nano-scale motor. Measuring 500 nanometers across, the electric motor has a diameter 300 times smaller than a human hair, small enough to ride on the back of a virus.
The motor is proof that "true devices" can be engineered from nanotubes - unlike nano-transistors that have been manufactured previously, the new device can be connected to external wires and its rotation controlled.
"It's the smallest synthetic motor that's ever been made," said Alex Zettl, professor of physics at UC Berkeley and faculty scientist at Lawrence Berkeley National Laboratory. "Nature is still a little bit ahead of us - there are biological motors that are equal or slightly smaller in size - but we are catching up."
The gold rotor turns on a carbon nanotube shaft, powered by two charged stators etched on a silicon surface. While the entire motor is about 500 nanometers across, the part that rotates is between 100 and 300 nanometers long and the carbon nanotube shaft to which it is attached is just a few atoms across, perhaps 5-10 nanometers thick according to the researchers at Berkeley.
Potential applications for the micro-motor include use as a switch in optical circuits or the rotor could be used to mix liquids in microfluidic devices.
Professor Zettl and his UC Berkeley graduate students and post-docs reported their achievement in the July issue of Nature.