A 'Muscle' on a Chip
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News Release - School of Physics,
University of New South Wales
Friday 17th December 1999
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Hold a litre of beer at arm's length
for a minute and your arm will tire -just as if it had been doing
work. Yet physicists will tell you that as you did not move the
beer, your arm did no work. Your arm obviously disagrees. So what's
going on? Researchers in UNSW's School of Physics have conducted
an experiment that might help provide an answer.
Using a specially made ratchet-shaped
"wire" so thin that even a single electron has difficulty moving
along it, they have shown that electrons can be made to move forward
or backward by controlling the shape of the wire. Their paper 'Electron
Tunneling Ratchets'will be published in the United States journal
Science
on December 17.
Dr Heiner Linke, the physicist leading
the experiment and an Australian Research Council Fellow, said the
experiment demonstrated that, at the atomic scale, the random movement
of very small particles (electrons in this case) could be converted
to do useful work. "A similar thing happens in a muscle where millions
of individual molecules act together to generate force," he said.
"To hold the molecules on track, and to keep the muscle contracted,
energy needs to be expended contineously".
"The ability to direct the motion of
small particles by controlling the shape of the structure they are
in has quite a number of applications," said Dr. Linke. "A related
technique has been developed in biotechnology to quickly separate
different-sized DNA fractions."
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Image Above :
An electron microscope image of a 'ratchet' for electrons.
The area high-lighted in orange forms a very thin channel
in which the motion of electrons can be controlled. Due to
a quantum mechanical effect, the direction of the electron
current changes with temperature. Each ratchet is about one
micrometer in size.
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In the experiment, the UNSW researchers
and collaborators at Lund University in Sweden found that the direction
of the electron motion could be controlled by tuning the temperature
or the shape of the device, which was made from gallium arsenide,
a material used for high-performance chips in microelectronics.
"Basically we made a new type of electronic device with quite unusual
properties," said Dr Linke.
"We are excited about this because it
demonstrates that artificial materials may be used to explore processes
in living creatures" said Linke. "Learning from Nature how to do
engineering on a molecular scale, and combining this knowledge with
microtechnology, has huge potential for a wide range of technological
applications."
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Further Information
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Link
to the original article.
A
feature on related work: Physics World, March 1999.
Department
of Condensed Matter Physics, University of New South Wales
Division
of Solid State Physics, Lund University
For further information contact:
Dr
Heiner Linke: hl@phys.unsw.edu.au
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