Design and fabrication of gas sensor based on nanostructure conductive polypyrrole for determination of volatile organic solvents

In this work, electrically conductive polymers have been prepared by polymerization of pyrrole on surfaces of commercial polymer fibers in the presence of an oxidizing agent. The resistance of polypyrrole-coated fibers was investigated and related to coating conditions, which was controlled by adjusting the reactant concentrations. The effect of initial treatment with monomer or oxidant prior to polymerization reaction with regards to resistance of sensor was optimized. The morphology of the conducting film on the surface of the fibers was examined by scanning electron microscope (SEM), indicating a strong dependence of the processing conditions. The sensing behavior of polypyrrole-coated fiber in the presence of different volatile organic compounds (VOCs) is studied experimentally. Effects of functional group and polarity of organic molecules on responses of the PPy-coated fiber sensor (PPy-CFS) were investigated. The PPy-CFS had demonstrated fast response time (<1 s), high sensitivity for various polar molecules and good reproducibility when reused. The sensitivity of the PPy-CFS for various molecules was in the following order: pyridines > acetonitrile > DMSO > ROHs > aldehydes > ketone > benzene derivatives ≫ alkanes.