Engineering and chemistry aspects of the well-known conductive polymers as sensors: Characterization, mechanism, synthesis, scale-up: A review

In this research, the conductive polymers including polypyrrole (PPy), polyaniline (PANI), and polythiophene (PTh) and their hybrids in the role of sensors were studied for the detection of the gas molecules. The synthesis principles, sensing performance, sensing mechanism, characterization of the conductive polymers, and scale-up discussion have been investigated. In addition, the impact of the operating conditions including temperature, humidity, gas concentration, time, recovery, and common additives like tin oxide, iron chloride, and Pd were analyzed. Sensitivity, conductivity, and response were discussed as criteria to evaluate the efficiency of the sensors. The difference of conductive polymers in the gas sensing returns to the level of porosity and morphology in the different conductive polymers. The results reveal that PANI and its composites are the desired choice for sensing toxic gases even in industrial centers or commercial scales.