P1.8.3 Ink-Jet Printed Conducting Polyaniline based Flexible Humidity Sensor

Abstract

Ink-Jet Printed, Intrinsically Conducting Polymer (ICP), polyaniline have been used for humidity sensing at room temperature.Polyaniline based, aqueous ink-jet printable ink has been synthesized by single step, chemical oxidative polymerization technique.Sulphonic acids were used as a dopant during the in-situ polymerization process.This is a single step polymerization process for the direct synthesis of conducting emeraldine salt phase of the polymer as an ink formulation.The synthesized polyaniline ink was further characterized by spectroscopic (UV-Vis.and FT-IR) analysis which confirmed the presence of conducting emeraldine salt phase of the polymer.The viscosity of the ink was measured by using Brook-field viscometer.The successive trials were performed for the printing of IDT pattern on the flexible, untreated polymer substrate using HP ink-jet-printer.The printed sensor was subjected for the humidity sensing measurements.The change in the resistance with change in the %RH was observed.It is suggested that the increase in conductivity at high humidity may be related to a vapour-induced change in the transfer of charge carriers between the polymer chains.The synthesized polyaniline based ink can also be considered as a good candidate for variety of ink-jet printed low cost electronics devices.