Understanding the response of nanostructured polyaniline gas sensors

Polyaniline/Ag nanocomposite gas sensors have been fabricated with a single-step technique. The current response of the sensors to triethylamine and toluene was monitored and analyzed. The time dependence of the response to the two gases of the sensors was found to be exponential and was fit to chemisorption and diffusion models. The equilibrium absorption amounts from the chemisorption model were found to obey a Langmuir isotherm. The results of the diffusion model to the data were consistent with a dual sorption process, i.e., diffusive and non-diffusive adsorption sites. The estimated diffusion coefficients were found to increase with the concentration of diluent, probably due to the swelling of the polymer by the organic vapors. Our results suggest that both models can be employed to mathematically fit the sensor response.