Conference extols promise of nanotech

By SCOTT R. BURNELL, UPI Science Correspondent  |  Oct. 11, 2002 at 5:35 PM
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BETHESDA, Md., Oct. 11 (UPI) -- Researchers examining nanotechnology, the science of manipulating matter at the atomic or molecular scale, have yet to tap the discipline's richest possibilities, despite ongoing, exciting discoveries, scientists said Friday.

Science has only reached the foothills of a metaphorical Mount Everest when it comes to nanotech, said Mildred Dresselhaus, a professor at the Massachusetts Institute of Technology in Cambridge, Mass., who has dealt with structures at the nanometer scale for more than 20 years.

A nanometer is to an inch what an inch is to 400 miles.

Researchers are constantly increasing the pace of their advances in understanding the nanorealm, Dresselhaus told attendees at the 10th Foresight Conference on Molecular Nanotechnology.

"There was a discussion about 10 years ago concerning putting the contents of the Library of Congress in a device the size of a sugar cube," she told the conference. "(Nanotech researchers) can do better than that now."

The key to nanotech's promise lies in the unique properties matter exhibits at that scale, Dresselhaus said.

When a chunk of material is less than about 30 nanometers in size, she said, it comes under the control of quantum mechanics, where physical laws are based on interactions among individual atoms and subatomic particles.

Gold's interaction with light changes as it is divided into smaller and smaller particles, so much so that its color shifts from yellow into the red and even infrared frequencies.

Even more interesting phenomena occur, she said, when scientists confine such infinitesimal amounts of matter into structures such as a two-dimensional nanowire or even a "quantum dot," essentially a one-dimensional cluster of atoms.

For instance, a sufficiently narrow nanowire of the element bismuth, an electrically conductive metal in bulk quantities, takes on the properties of a semiconductor such as silicon, Dresselhaus said.

Similar qualities are seen in carbon structures called nanotubes, said Cess Dekker, a professor at the Delft University of Technology in the Netherlands. Nanotubes essentially are a rolled-up sheet of graphite, forming a hollow cylinder with walls one atom thick, he said.

Experiments have shown that nanotubes act as coherent quantum wires for electricity, displaying semiconducting or even metallic qualities for hundreds or thousands of nanometers, Dekker told the conference. The tubes are therefore excellent candidates for molecule-sized electronic circuits and several research teams have incorporated nanotubes into common circuit types, he said.

The tubes' electrical qualities change in the presence of proteins and other organic structures, so they also could form extremely sensitive biological sensors, he said.

DNA, the chain of chemicals that encodes the genetic structure, is itself only a couple of nanometers wide, and some researchers theorize it could be incorporated into circuits, Dekker said.

Ongoing experiments seem to indicate DNA is too much of an electrical insulator for that job, he said, but its ability to self-assemble could put it in the role of "gluing" nanotubes into the right spots.

Nanotechnology also plays a key role in creating organic electro-optical materials, substances capable of oscillating light rapidly enough to enable next-generation computing products, said Larry Dalton, a professor at the University of Washington.

Such materials are expected to form the basis of communications networks that are capable of handling hundreds of times as much information as current inorganic semiconductor systems, he said.

Nanoengineering and theoretical studies of nanoscale chemical properties have helped overcome the materials' reluctance to align their light-emitting structures properly, Dalton told the conference.

Current EO substances are about 1,000 times more effective than those available a decade ago, he said. The improvements also have led to EO materials that can withstand many of the processing techniques used on computer chips, leading to easier integration with existing systems, he said.

The conference is organized by the Foresight Institute, a Palo Alto, Calif.,-based non-profit organization working to ensure the proper development of nanotech and other emerging applications.

The conference's primary sponsors include computer systems manufacturer Sun Microsystems and Zyvex, a Richardson, Texas,-based company exploring methods of assembling devices molecule by molecule.

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