The little light-sensitive molecule that could

By Kimberly Patch, Technology Research News

Although researchers have been developing construction techniques for building nanoscale structures for some time, there have been fewer ideas about the practical matter of moving materials around the microscopic construction sites.

A team of Tel Aviv University researchers is working to fill that gap with with a plan for tiny freight trains.

The researchers' nanoscale locomotive is made up of a photosensitive molecule attached to particles that fit the depressions of an eggcrate-like surface. The device moves when a laser activates the spring-like molecule, stretching a particle forward to the next depression. The locomotive could be as small as a few nanometers long, according to Markus Porto, a postdoctorial researcher at Tel Aviv University.

The locomotive will be able to carry a tiny payload and turn on a nanoscale dime: the eggcrate track, which is broad as well as long, allows the tiny train to move in all directions, and the laser control enables real-time route changes.

Laser control also means the locomotive is not tethered to a power source. "That's an elegant way of doing it... a sort of a hands-free way of moving around a nanoscale object," said Joseph Lyding, professor of electrical engineering and computer engineering at the University of Illinois' Beckman Institute.

Because the locomotive is capable of carrying cargo, it is potentially useful for applications like ferrying materials around nanoscale factories to produce custom molecules, said Porto.

In addition, the nano-locomotive will be able to go very fast. "When you get down to the nanometer scale you can have very high [mechanical] speeds," said Lyding. "So in that light nano locomotion can serve all sorts of useful functions," he said.

A realistic speed for the nano-locomotive will likely be several micrometers or tens of micrometers per second, said Porto. "This does not sound [like] a lot, but... this means that the engine moves 100 to 1000 times its own length per second," he said. Scaling that speed up, in order to go 500 times its own length per second, a typical four-meter-long car would have to go 7200 kilometers per hour, said Porto.

According to Porto, a prototype of the engine could be assembled fairly quickly. "All ingredients needed for an actual realization [exist] in laboratories. Since the field of nanotechnology progresses very quickly we might see applications sooner than we think, maybe even in a few months," Porto said.

"It seems pretty straightforward to go from an idea to some type of a prototype," said Lyding, who added that a prototype should easily be viable within a few years.

Porto's colleagues on the nanoscale locomotive project were Tel Aviv University professors Michael Urbakh and Joseph Klafter.

The three researchers have also worked out the mechanics of a nanoscale engine that converts random motion into directed motion. A paper describing the plan is scheduled for publication in the July 17 issue of Physical Review Letters.

Macro-scale engines convert the random motion of the heat from burning fuel into directed motion. But these engines cannot be scaled down to the nanometer size because the thermodynamic laws macro-scale engines take advantage of do not apply to single atoms or molecules, said Porto.

The research was funded by the Israel Science Foundation, The German Israeli Foundation, the Submicron Imaging and Stimulus Induced Transformation of Organic Molecular Adsorbates at Surfaces (SISITOMAS) program of the European Community Research Network For Training and Mobility of Researchers, the German Israeli Project Cooperation on Future Oriented Topics (DIP), and a Feodor Lynen fellowship of the Alexander von Humboldt foundation in Germany.

Timeline:   < 1 year; < 3 years
Funding:   Institute; Government
TRN Categories:   Nanotechnology; Semiconductors and Materials
Story Type:  News
Related Elements:   Animations and technical abstracts


July 12, 2000

Page One

Bendable nanotubes store bits

Protein-coated chip sniffs out bacteria

The little light-sensitive molecule that could

Fault-tolerant free speech

Chemical reaction zips nanowires onto silicon


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