Investigation on resistive humidity sensing in sulfosuccinic acid doped polyaniline films

In this work, the possibility of humidity sensor based on conducting polymer, polyaniline (PANI) doped with a novel organic dopant, sulfosuccinic acid (SSA) is explored. PANI-SSA based sensors show considerably high humidity sensitivity, limit of detection (LOD) of 8%RH and linearity covering a wide range of relative humidity (RH) from 30% to 80%. Molar ratio of PANI-SSA is varied to get optimum sensing response at around 1:2 ratio. In order to understand the physical phenomena behind the humidity sensing property, various characterizations such as thickness dependent sensing response, thermo gravimetric analysis, scanning electron microscopy, temperature dependent conductivity as a function of RH are performed. The origin of the sensing response is attributed to the adsorption of water molecule at the surface of PANI-SSA films leading to the lowering of activation energy of electron hopping.