Robust fabrication of selective and reversible polymer coated carbon nanotube-based gas sensors

In this study, a systematic investigation was carried out to produce reliable and reproducible polymer coated nanotube sensors to enhance their selectivity against exposed analyte molecules. To do this, a series of uniformly distributed, randomly aligned SWNT films were prepared via vacuum filtration from suspended HiPCO nanotubes and transferred to photolithography patterned silicon chips with high reproducibility and yield. The SWNT film density was optimized for detection of dimethyl methylphosphonate and ammonia at the percolation threshold range of nanotube electric conductance. Cyclic voltammetry (CV) was used to polymerize seven different polymers in aqueous solutions and coat a thin layer onto optimized SWNT films. Polymer coated SWNT-based sensors were analyzed for selectivity for a variety of gases. Results indicate that the electropolymerization of different polymers onto nanotube surfaces can be a simple and promising way to obtain controlled, reliable, and modulated response for various analyte molecules.