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 × 10
^-6
Scm
^-1
to 1.1 × 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 (N
_g
) to partially nanofibrous (pN
_f
). We investigate the effect of observed morphologies of PANI-paper composites on their resistive-type humidity sensing performances. The partially nanofibrous (pN
_f
) PANI-paper exhibits a bimodal humidity response due to polymer-swelling effect at higher humidity (≥ 55% RH). However, the nanogranular (N
_g
) PANI-paper yields a unimodal, linear humidity response within the humidity range, 16-96.2% RH, with a sensitivity of 9.79 kΩ/% RH (R
²
≈ 0.996). Hence, the N
_g
PANI-paper is a promising alternative to the conventional humidity sensors fabricated on ITO glass/bare glass/PET substrates.