13 March 2010

Thermopower Waves: A New Discovery at MIT

Think of electrons as flotsam on a wave as it moves across the surface of the ocean. That's how scientists at the Massachusetts Institute of Technology (MIT) describe a previously unknown phenomenon, which they are calling "thermopower waves."

A thermal wave is a moving pulse of heat that travels along microscopic wires known as carbon nanotubes to create an electrical current. (See the video below.)

Michael Strano, MIT's Charles and Hilda Roddey Associate Professor of Chemical Engineering, described this discovery at the press briefing for last week's MIT Energy Conference in Boston.

Strano was the senior author of a paper describing the new findings that appeared in Nature Materials earlier this week; the lead author was Wonjoon Choi, a doctoral student in mechanical engineering at MIT.

Carbon nanotubes are submicroscopic hollow tubes made of a "chicken-wire-like" lattice of carbon atoms. Nanotechnology is an emerging scientific research area with wide ranging potential applications in medicine, electronics, and energy.

Because this is such a new discovery, Strano said, it's hard to predict exactly what the practical applications will be.

One potential use may be developing new kinds of ultra-small electronic devices, perhaps the size of grains of rice, with sensors or treatment devices that could be injected into the body or "environmental sensors that could be scattered like dust in the air."

Sounds like "Fantastic Voyage," the 1966 sci-fi film that featured nanoscale humans entering the body to treat a patient. But there's more to their theory than meets the eye, well, at least the naked eye anyway, especially for electricity production.

Strano explained that "by using different kinds of reactive materials for the coating on the nanotubes the wave front could oscillate, thus producing an alternating current."

"That would open up a variety of possibilities," Strano said. "Because alternating current is the basis for radio waves such as cell phone transmissions, but present energy-storage systems all produce direct current."

Time will tell if this new breakthrough revolutionizes energy production or battery technology. Meanwhile, Strano's research is ongoing.

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