Conductance measurement of single-walled carbon nanotubes in aqueous environment

We report measurement of conductance of single-walled carbon nanotubes in aqueous media using a field effect geometry in which source and drain electrodes are protected with a photopolymerized epoxy. Without this protection, exposure to aqueous media degrades the device instantly. The 2.6 mum width open slits are prepared by photolithography at the central region between source and drain electrodes, whose spacing, or channel length, is 5 mum, so that only the nanotube channel can be directly exposed to an aqueous environment, while the metal-nanotube junctions are protected. For protected devices, the response to water as characterized primarily by changes in threshold voltage is reversible and reproducible. (C) 2003 American Institute of Physics.