HARVARD GAZETTE ARCHIVES

Doctoral student Yu Huang and other researchers working on nanoscale technology - technology in the nanometer, or one-billionth of a meter, range - have been working to create electronics components from the bottom up, by assembling them from individual molecules. (Staff photo by Stephanie Mitchell)

Harvard doctoral student Yu Huang might just have an answer for them.

Huang, a student in Mark Hyman Professor of Chemistry Charles Lieber's lab, has used fluid flows to arrange tiny bits of wires that are just billionths of a meter wide into millimeter-long lengths. Further, by switching the direction of subsequent flows, Huang has been able to create grids of these wires that could function as electronic circuits. The ability to layer these grids lays the foundation for creating more complex devices.

Huang's work made her one of six winners of the Collegiate Inventors Competition this year and the second winner from Lieber's lab in two years. Announced in November, the award is sponsored by the National Inventors Hall of Fame and comes with a $20,000 prize. The award is designed to identify the most advanced collegiate technology research in all fields of science.

Huang's work, which was cited as "breakthrough of the year" in 2001 by Science Magazine, represents just another step along the research fast track to increasing miniaturization. The relentless increase in computer chip power in recent decades has largely resulted from the ability to pack more and more circuits onto chips. That means the circuit components have to become smaller and smaller, making them more difficult to manufacture and to manipulate.

Huang and other researchers working on nanoscale technology - technology in the nanometer, or one-billionth of a meter, range - have been working to create electronics components from the bottom up, by assembling them from individual molecules. Collectively, their work promises computers far more powerful than those available today and so small they could become part of a new generation of smart devices.

Other researchers have used techniques such as direct manipulation of individual nanowire bits and electronic fields to create crossed nanowire structures. Huang's technique, however, is potentially lower-cost, faster, and scalable, meaning it can be done on scales large enough to be useful in manufacturing.

Under Huang's process, tiny bits of nanowires made of silicon, gallium phosphide, gallium nitride and indium phosphide were suspended in an ethanol solution. The solution was then directed across a mold with tiny channels in it. The nanowires aligned themselves in the direction of the flow in much the same way that a log floating down a river tends to point downstream and align itself with the river's current. The faster the flow, the less deviation in alignment was found.

By switching the flow to another direction, a second set of nanowire bits can be aligned to form a grid with those deposited during the first flows.

"We are excited about this new development," Huang said.

Huang, who did her undergraduate work at the University of Science and Technology of China, has been at Harvard for the past three years. She said she's always had an interest in science. The work of a University of Science and Technology professor sparked her interest in nanotechnology.

Several manufacturers have already shown interest in Huang's invention, Huang said. Intel, which has been collaborating with Lieber's lab on what Lieber termed the "next-next-next-generation chip," is interested, but Lieber said any chip technology incorporating the process is at least a decade out.

What is closer, however, is using the technique to create biosensors that could detect different biological molecules, Lieber said, something that could be used to create tests for different diseases or for impurities in drug and blood supplies.

Huang speaks of a future where medical probes are small enough to do surgery on individual human cells and where contact lenses contain small displays on which a wearer could watch television.

"It's quite amazing the tiny stuff you can build. It's just fascinating," Huang said.

alvin_powell@harvard.edu