Northwestern researchers develop bistable nanoswitch Oct. 16, 2006 — Scientists from Northwestern University have demonstrated a novel carbon nanotube-based nanoelectromechanical switch exhibiting bistability based on current tunneling. The device could help advance technological developments in memory chips and electronic sensing devices. The research was published online by the scientific journal Small. “We believe the unique characteristics of this nano device will likely lead to many high-impact applications in the field of nanoelectronics and nanosensors,” said Horacio Espinosa, professor of mechanical engineering in the McCormick School of Engineering and Applied Science, in a prepared statement. Espinosa and Changhong Ke, a former graduate student of Espinosa’s, co-authored the paper. “Although several carbon nanotube-based NEMS devices have been proposed, frankly, none of them has reached the level of commercial success,” said Espinosa. “There are many challenges associated with nanofabrication and reliability.” The device is made of a free suspended multiwalled carbon nanotube interacting electrostatically with an underlying electrode. In the device circuit, there is a resistor in series with the nanotube, which plays an important role in the functioning of the device by adjusting the voltage drop between the nanotube and the underlying electrode. Espinosa and Ke demonstrated the behaviors of the device by mounting individual carbon nanotubes to the tip of a tungsten probe using a nanomanipualtor inside a scanning electron microscope. Then the nanotube was actuated by applying a potential to an adjustable micron-size gap between the nanotube and an electrode. The motion of the nanotube was recorded by the electron microscope, and the current in the circuit was recorded by a source-measurement unit. The research was supported by the Federal Aviation Administration and the National Science Foundation.