Nanoengineered Conductive Polyaniline Enabled Sensor for Sensitive Humidity Detection

We report results of the studies relating to the fabrication of a paper-based humidity sensing element comprising a nanostructured polyaniline (PANI) coating on a filter paper substrate. The electrical conductivity of the PANI integrated conductive paper increases from $1.9\times 10^{-6}$ Scm−1 to $1.1\times 10^{-1}$ Scm−1 on modification of the polymerization protocol. This increase in conductivity is ascribed to the change in morphology of the PANI coating from nanogranular ( $\text{N}_{\text{g}}$ ) to partially nanofibrous (pNf). We investigate the effect of observed morphologies of PANI-paper composites on their resistive-type humidity sensing performances. The partially nanofibrous (pNf) PANI-paper exhibits a bimodal humidity response due to polymer-swelling effect at higher humidity (≥ 55% RH). However, the nanogranular ( $\text{N}_{\text{g}}$ ) PANI-paper yields a unimodal, linear humidity response within the humidity range, 16–96.2% RH, with a sensitivity of 9.79 $\text{k}\Omega $ /% RH ( ${R}^{2}~\approx 0.996$ ). Hence, the $\text{N}_{\text{g}}$ PANI-paper is a promising alternative to the conventional humidity sensors fabricated on ITO glass/bare glass/PET substrates.