Printer Friendly

Nanotubes central to new rotating device. (Miniature Motor).

Motors, pumps, and other electromechanical devices are tinier than ever--and getting even smaller. Now, for the first time, researchers have used miniature, nested cylinders, called multiwalled carbon nanotubes, to make a motor that's only 300 nanometers long.

A variety of molecular-scale motors and other actuators are under development around the world, but many rely on biological parts, such as enzymes (SN: 11/9/02, p. 291). In comparison, the new system--built by Alex Zettl's research team at the University of California, Berkeley and the Lawrence Berkeley National Laboratory--is synthetic and might operate under conditions that biological components find unfriendly, such as extreme heat and harsh solvents.

Zettl's graduate students Adam Fennimore and Tom Yuzvinsky fabricated the new actuator on a silicon wafer. The rotor consists of a gold plate centered on a nanotube shaft whose ends are anchored to electrically conductive pads. The plate rotates when a voltage is applied to three stationary gold electrodes positioned on the wafer a short distance from the shaft. The nanomachinists report their results in the July 24 Nature.

In the team's first experiments, large voltages induced the entire shaft to twist only 20 degrees. That could prove useful, Zettl notes, but his team was aiming for a nanomotor capable of full rotations.

A route toward this goal emerged from previous studies. Three years ago, Zettl and graduate student John Cumings found that the interior tubes of a multiwalled carbon nanotube could move freely within the more exterior tubes (SN: 7/29/00, p. 71).

To take advantage of this property, Zettl's team severed the outermost

shell--or several of them--on either side of the rotor plate. This step decouples the rotor-bearing segment of the shaft from the rest of the multiwalled nanotube.

With a judicious combination of small voltages applied to the stationary electrodes, the researchers could make the rotor move any amount between 0[degrees] and 360[degrees]. They also made it flip back and forth quickly between two positions thousands of times and found that it showed no wear.

"This first demonstration of a rotational actuator using a nanotube axle and bearing is a truly exciting advance that could have important technological applications," comments Ray Baughman of the University of Texas at Dallas.

Zettl predicts that uses for nanoscale motors are "going to be huge and very diverse." Potential examples include switches in optical communication devices and pumps that move solutions though minuscule channels for mixing and analysis.
COPYRIGHT 2003 Science Service, Inc.
No portion of this article can be reproduced without the express written permission from the copyright holder.
Copyright 2003, Gale Group. All rights reserved. Gale Group is a Thomson Corporation Company.

Article Details
Printer friendly Cite/link Email Feedback
Author:Gorman, J.
Publication:Science News
Geographic Code:1USA
Date:Jul 26, 2003
Previous Article:Platelets in blood may guide immune response. (Beyond Clots).
Next Article:Mastering the mixer: the frustrating physics of cake mix and concrete.

Related Articles
Superlong nanotubes can form a grid. (Nanoscale Networks).
IBM creates world's smallest light-emitting molecule. (Top Technology Showcase).
Nanotubes make tough threads. (Super Fibers).
Cinching nanotubes into tough fibers.
Nice threads: the golden secret behind spinning carbon-nanotube fibers.
Savvy Sieve: carbon nanotubes filter petroleum, polluted water.
Nanotech goes to new lengths: scientists create ultralong carbon nanotubes.
Carbon nanotubes drive X-ray scanner.
Electronics gets Y's: nanotubes branch out as novel transistors.
Teasing apart nanotubes: fast-spun carbon fibers may feed an industry.

Terms of use | Privacy policy | Copyright © 2021 Farlex, Inc. | Feedback | For webmasters |