AMHERST, Mass. - Nanotechnology, in which molecules and atoms are assembled like tiny building blocks, is an extreme science: in this hybrid of chemical engineering, physics, and polymer science, University of Massachusetts researchers are fabricating devices and materials too small to be seen without an electron microscope.
But despite its infinitesimal size, nanotechnology may be looming as the next giant leap in the microelectronics industry, the researchers say. Switches, sensors, and transistors that can only be seen with powerful electron microscopes may one day offer major advantages in a variety of fields, from computers that are faster and more capable, to devices that offer more efficient chemical separations and reactions, to ultrasensitive magnetic sensors that can detect landmines or trace contaminants, to tiny systems that can cool individual computer chips.
"This is a very hot research topic, with a lot of potential in applications," says University of Massachusetts physicist Mark Tuominen. The National Science Foundation in fact has recently launched a major initiative in nanotechnology research. Two separate UMass research teams were awarded grants totaling more than $1 million under the very competitive NSF program. Only 24 awards were granted across the nation as part of the initiative.
The UMass research relies on stencils and scaffolds known as "nano-templates." The templates enable the researchers to apply metal to the tiny devices with extreme precision, Tuominen said. For instance, they can fill microscopic tubes with metal, creating nanowires that are 10,000 times thinner than a human hair. Researchers envision nanowires serving as cables in the tiny devices.
The physics/polymer team, including Tuominen, along with Thomas Russell and Jacques Penelle, both of polymer science and engineering, creates devices using nano-templates composed of long strings of molecules called polymers. These polymers are specially designed so that they will arrange themselves in a precise order when they are set on a silicon surface. Much of the production takes place in a "clean room," as a speck of dust would ruin a device. Potential uses include the ultrasensitive sensors mentioned above, as well as thermo-electric coolers used in cooling computer chips, and molecular devices, aimed at microelectronics in the next century.
The second team, James Watkins and his chemical engineering colleagues Michael Tsapatsis and Dionisios Vlachos, is working on producing membranes with precisely engineered nanoscopic structures. These membranes are particularly useful in offering more efficient separations and reactions in the chemical industry. The team deposits metal clusters within porous ceramic templates using supercritical fluids (SCFs), particularly carbon dioxide. SCFs are highly compressed gases that have some qualities of gases, and some of the qualities of liquids, Watkins explains. This combination of characteristics makes them uniquely useful as solvents for depositing metals within these confined environments.