One-step fabrication of a polyaniline nanofiber vapor sensor

A single-step, bottom-up technique has been used to fabricate sensors, based on conducting polymer nanofibers. A small amount of an aqueous solution containing aniline, a dopant, and an oxidant was placed on an interdigitated electrode array. Ultraviolet (UV)-irradiation of the solutions affected polymerization, yielding a highly porous film of polyaniline nanofibers with a mean diameter of around 100 nm and a length on the order of 1 μm. Solutions that were not irradiated formed bulk-like polyaniline (PANI) films. Nanofibers and bulk polyaniline sensors were exposed to chloroform, a weak proton donor; to toluene, a vapor that causes polymer swelling; and to triethylamine, which alters the doping level. Because of their higher surface areas, the response times of the fiber sensors were about a factor of 2 faster, with the current variations up to 4 times larger than those of the bulk polyaniline sensors. These results suggest methods for the advancement of simple and environment-friendly production of organic nanofiber-based sensors and electronic devices.