US physicists create World's smallest synthetic motor


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.

About the Author
Mike Hanlon Mike grew up thinking he would become a mathematician, accidentally started motorcycle racing, got a job writing road tests for a motorcycle magazine while at university, and became a writer. As a travelling photojournalist during his early career, his work was published in a dozen languages across 20+ countries. He went on to edit or manage over 50 print publications, with target audiences ranging from pensioners to plumbers, many different sports, many car and motorcycle magazines, with many more in the fields of communication - narrow subject magazines on topics such as advertising, marketing, visual communications, design, presentation and direct marketing. Then came the internet and Mike managed internet projects for Australia's largest multimedia company, (Australia's largest Telco), (Australia's largest employment site),,, and a dozen other internet start-ups before founding Gizmag in 2002. Now he writes and thinks. All articles by Mike Hanlon
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