ITHACA, N.Y. -- Six years ago Cornell University researchers built the world's smallest guitar -- about the size of a red blood cell -- to demonstrate the possibility of manufacturing tiny mechanical devices using techniques originally designed for building microelectronic circuits.
Now, by "playing" a new, streamlined nanoguitar, Cornell physicists are demonstrating how such devices could substitute for electronic circuit components to make circuits smaller, cheaper and more energy-efficient.
Lidija Sekaric, who built the new, playable nanoguitar while an Applied Physics graduate student at Cornell, described the project, along with other materials and device research in nanoelectromechanical systems (NEMS), at the 50th International Symposium and Exhibition of the American Vacuum Society, Nov. 2 to 7 in Baltimore. At the same meeting Harold Craighead, professor of applied and engineering physics at Cornell, presented a plenary talk reviewing the uses of NEMS in biology. Sekaric worked in the Craighead Research Group at Cornell, part of the Cornell Center for Materials Research study of NEMS systems.
NEMS usually refers to devices about two orders of magnitude smaller than MEMS (microelectromechanical systems). Craighead prefers to define NEMS as devices in which the small size is essential for the job, such as those that respond to very small forces or biosensors so small that they can measure the mass of a single bacterium.
Sekaric, now a researcher at IBM's Watson Research Center in Yorktown Heights, N.Y., worked with Cornell graduate student Keith Aubin and undergraduate researcher Jingqing Huang on the new nanoguitar, which is about five times larger than the original, but still so small that its shape can only be seen in a microscope. Its strings are really silicon bars, 150 by 200 nanometers in cross-section and ranging from 6 to 12 micrometers in length (a micrometer is one-millionth of a meter; a nanometer is a billionth of a meter, the length of three silicon atoms in a row). The strings vibrate at frequencies 17 octaves higher than those of a real guitar, or about 130,000 times higher.