Electrons Zap Clean Nanotube Sensors

After a single-walled carbon nanotube (SWNT) performs its function as a sensor, the molecules that have adsorbed on the tube’s surface need to desorb before the sensor can be reused. This is often a lengthy, inefficient process. Richard I. Masel, Amin Salehi-Khojin, and colleagues of the University of Illinois, Urbana-Champaign, have found that simply applying a strong electric current to the tubes quickly and effectively jolts off adsorbed alcohol, amine, phosphonate, and aromatic molecules (Science 2010, 329, 1327). In this proof-of-principle study, the group selected SWNTs with small defects in the structures, which the electrons jump over to gain a crucial boost in acceleration before interacting with the molecules. The researchers showed that the process doesn’t heat the tubes substantially. The lack of heating implies that the electron-promoted desorption “must be due to a nonthermal process whereby the analyte is removed from the nanotube surface in response to the current,” they write.