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Molecular motors could help research

By SCOTT R. BURNELL, UPI Science News   |   Jan. 21, 2002 at 4:35 PM
LAS VEGAS, Jan. 21 (UPI) -- Researchers said Monday they have combined organic molecules and similarly small pieces of metal to produce tiny motors capable of moving things dozens of times larger than the device itself.

Carlo Montemagno, a professor of mechanical and aerospace engineering at the University of California, Los Angeles, described the motors and other microscopic devices to a conference on microelectromechanical systems or MEMS -- devices ranging from the width of a human hair down to a few molecules in size.

The motor's key components, Montemagno said, are found in a complex of molecules that synthesize ATP, a chemical used as an energy source in all living things. Six of the molecular structures form the equivalent of a three-cycle, three-cylinder motor that surrounds a seventh molecule, the motor's "shaft," he said. The entire assembly is about 11 nanometers tall and 11 nanometers in diameter -- hundreds of times smaller than the width of a human hair.

Chemical interactions make the six cylinders flex in sequence, rotating the shaft. One way to harness this motion involves attaching a rotor to the shaft. Using techniques involved in manufacturing computer chips, Montemagno and his UCLA colleague Hercules Neves created nickel rotors about 700 nanometers long, and found the rotors and motors came together on their own.

The assembled motor completed eight revolutions per second and maintained its structural integrity, Montemagno said.

"It's equivalent to you taking a telephone pole about 2 kilometers long and spinning it eight revolutions per second in a swimming pool," he told United Press International.

Such an engine is useful, but not if it always is on. The researchers discovered individual zinc atoms will attach to certain points between the motor's cylinders, preventing them from flexing. Therefore, adding zinc to a solution containing the motors will shut them down, and flushing the zinc out starts them again. The motors continue to work after several repetitions of this process, Montemagno said.

That sort of performance could conceivably move ultra-small devices without relying on clumsy human hands.

"We've just started a project looking at ... having small sensors locomote themselves where you want them to go," Montemagno said.

Providing that sort of mobility within living tissue is a very attractive idea in medicine, said Marlene Bourne, a MEMS analyst with Cahners In-Stat Group in Scottsdale, Ariz.

"At least initially, (the motors) would probably have tremendous benefits in life science research," Bourne told UPI. "That's one area that's really benefiting from the involvement and advancement of MEMS and nanotechnology."

Apart from developing the technology to where it is commercially feasible, Bourne said the biggest hurdle will be moving the devices to clinical applications.

"If you start talking about machines in people's bodies, we're getting to the point where there will be some real questions about educating the public," Bourne told UPI. "(Another question is) do we need regulation in terms of how these (motors) will be used, for what purpose, and who gets to benefit from it?"

Other roadblocks include working with the motors in a real-world environment, Montemagno said. They currently are limited to water-based solutions.

Once the questions are resolved, however, the devices could reach the point of delivering chemotherapy drugs directly to cancer cells, Bourne said.

The possibilities of semi-organic MEMS devices are not limited to locomotion, either.

"There are mechanisms of biological energy ... which allow you to transform chemical energy into electrical energy within the structure of an engineered device," Montemagno told UPI. "The idea is to make machinery that can use the power of life, of living systems, to power these devices."

The long-term goal of this branch of research is to eliminate the need for chemical batteries in devices implanted in the body, Montemagno said. MEMS devices also can form filters to block particles only a few nanometers across, he said.

Bourne said such filtering technology also would be very consistent due to its engineered, consistent pore size. This could significantly boost the purity of manufactured pharmaceuticals, she said.

Co-sponsored by the Institute of Electrical and Electronics Engineers and the Robotics and Automation Society, the MEMS 2002 conference displayed the latest research into the molecule-sized systems. Scientists expect the technology to provide breakthroughs in several areas, including medicine, computers and robotics, in the next few years.

© 2002 United Press International, Inc. All Rights Reserved. Any reproduction, republication, redistribution and/or modification of any UPI content is expressly prohibited without UPI's prior written consent.
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