Bio-mimetic sensing characteristics of differently synthesized polyanilines towards the surrounding electrical and chemical energetic conditions

Abstract

Conducting polymers are recognized as responsive gels capable of responding to the changes in their surrounding environment through their unique electrochemical response. Various polyanilines at different reaction time were synthesized chemically and their properties were examined using TGA, UV-VIS spectroscopy, FTIR spectroscopy, cyclic voltammetry (CV) and coulovoltammetry (QV). To investigate their electrochemical sensing capabilities towards both electrical and chemical stimuli, the chronopotentiometric responses in HCl solutions were monitored by varying the working variables: the applied current and electrolyte concentration, at a constant charge obtained from respective QV. The consumed electrical energy during the electrochemical reaction was observed to change linearly with the driving current, while a logarithmic relationship was established with the electrolyte concentration. The electrical energy served as the sensing parameter, and the sensitivity was found to be associated with the reaction time during synthesis of the polymers, with longer chains exhibiting greater sensitivity. The experimental findings were validated using a theoretical equation. Applicability of polyaniline to act as a model material for designing bio-mimetic sensing devices using only two connecting wires is verified here as they mimic the electrochemical reactions of biological muscles comprising of natural polymeric chain.