Atom By Atom - Nanotechnology

Atom by atom, nanotechnology is becoming one of the fastest growing fields of study in the world. Nano, from the Greek "nanos" or "dwarf" refers to a nanometer or one billionth of a meter. Nanotechnology, then, is the science of creating and producing machines the scale of a billionth of a meter. With Universities, laboratories, and corporations all citing possible nanotechnology applications from digestible pills that seek out and kill cancer cells to pants that can clean themselves it's easy to see how this science is catching the creative eye of students and researchers alike.

At Michigan Tech, Yoke Khin Yap, assistant professor of physics, dreams of sensors that could detect any known toxin and fit in a soldier's shirt pocket. Of a supercomputer the size of your TechExpress card. Of a cable that's long, strong and light enough to lasso the moon.

Atom by atom, Yap and his research team are constructing nanotubes as small as a billionth of a meter across and a few hundred micrometers long. Inside a small, airtight chamber, a special laser blasts the raw material (carbon and, more recently, a mix of boron and nitrogen) and blows it through a plasma cloud. It crystallizes on a silicon substrate, atom by atom, ring upon ring, forming impossibly tiny, infinitely perfect tubes.

What these tubes may be capable of is anybody's guess. As the carbon in a No. 2 pencil is not the same as the carbon in the Hope diamond, so the properties of carbon nanotubes are vastly different from those of naturally occurring forms of the element.

"The bonding in the tubes is as strong as the bond inside a diamond," Yap said. "With this, you could make a cable five times lighter and five times stronger than steel. You could make super-light, super-strong plastic for use in your car, in aircraft, in rockets. You could form a cable and build an elevator to the moon."

Yap received a $506,000 National Science Foundation Faculty Early Career Development grant, known commonly as a CAREER Award, to begin making designer nanotubes that might someday change the fabric of our lives. (In some respects, that's already happening: Yap himself has a pair of dirt-resistant pants, made possible by another type of nanomaterial.) The goal of the NSF project is to build nanotubes with various physical properties depending on the elements used in their construction and how those elements fit together.

Yap is just the person to do it. He is the only researcher in the world to successfully build nanotubes on silicon chips from the elements nitrogen and boron, which, compared to carbon, have been notoriously difficult to manage. "They are promising, but so difficult to make," he says. "Carbon nanotubes will grow at 600 degrees celsius, but boron nitride tubes typically need 1,200 degrees," about the temperature of molten lava. Yap has succeeded in growing them at the more-manageable 600 degrees, aligned in one direction and free of impurities. The problem with nanotubes made with carbon is that they oxidize at high temperatures, which can limit their applications. "But the boron nitride nanotubes resist oxidation, so they wouldn't burn up as easily," Yap says.

With his CAREER Award, Yap wants to begin building nanotubes with all three elements, incorporating the benefits of each. "We want to mix them together precisely, atom by atom," he says. "That would be true nanotechnology."

Because nanotubes can behave like semiconductors, they have huge potential for use in electrical and photonic devises. With funding from the military, Yap has already been investigating the electrical properties of carbon nanotubes, which have the potential to make computers much smaller and faster, and displays that are thinner, lighter and brighter, all at much lower power consumption.

However, he is particularly intrigued by the promise of nanotubes custom-built with boron, nitrogen and carbon. "It is possible to tune the band gap of boron nitride nanotubes by substituting carbon to make boron carbon nitride nanotubes," he said. Thus, you could tailor nanotubes for high-powered electronic and photonic devices, such as lasers, that can't be made using nanotubes constructed of carbon alone.

You could also use this technology to build nanoscale sensors, each designed to detect a specific chemical or biological molecule, he adds. "The substance would bind onto a receptor molecule, which would send out a warning signal," Yap says. "It could be used on the battlefield, in airports, as a diagnostic tool . . . There are so many possibilities."

Another exciting development at Tech is one of the nation's first Nanotechnology minors. This minor developed as a result of a NSF grant received in 2003 which brought together researchers from 11 departments to help students address topics as diverse as biotechnology, ethics and medicine. Because nanotechnology has such huge potential, with applications in engineering, the sciences, social sciences and the humanities, the minor is an excellent fit for students pursuing almost any bachelor's degree. In addition to the scientific perspective, students will be introduced to nanotechnology's societal and ethical implications, an aspect of the minor that's critical in a discipline with such revolutionary promise. "Visionaries, researchers and agencies that fund research think that nanotechnology will be the next revolution in society, similar to the information revolution we're in now," said John Jaszczak, associate professor of physics, a principal investigator on this NSF grant. "I think it's pretty exciting we're able to prepare students now."