Carbon monoxide sensitivity of vacuum deposited polyaniline semiconducting thin films

By utilizing the semiconducting polymeric thin films on various substrates a new simple and quick technique has been developed for sensing carbon monoxide gas. The thin films of polyaniline were prepared by vacuum deposition. The particular doping combination in the polymer makes the sensor specific for detection of CO. Polyaniline was prepared by copolymerization of aniline and formaldehyde. Metal halides with specific concentrations were used as dopants to make polyaniline film specific for CO sensing. The thickness of the film was measured by using quartz thickness monitor. The thickness of the film was found the order of 1000 A. Sensitivity of the film is measured by using the relation S = (I-c - I-o)/I-o, where I-e is current after exposure and I-o is the current before exposure the sensor to CO, respectively. The sensor, investigated in the environment of various gases as CO, HCN and NH3, showed the high sensitivity of order 800 for carbon monoxide gas and response time of the sensor is 5 s for carbon monoxide gas. The fabrication process, the morphological, structural and electrical characterization of the sensor in regard to detection of CO has been described. (C) 2004 Elsevier B.V. All rights reserved.