Fabrication of selective gas sensor by membrane affect on the nano-sized conducting polypyrrole

In last few years, many researching groups have been focusing their attention on the development of selective gas sensors towards detection of VOCs [1]. A wide range of materials of organic and inorganic origin are used as sensing elements. Polymer-based selective gas sensors have received considerable interest in recent years, mainly due to their selective gas sensing ability, by measuring the conductivity changes as a function of the polymer doping by gases [2]. In this work electrically conductive fibers have been prepared by polymerization of pyrrole on surfaces of commercial polymer fibers in the presence of FeCl3 as an oxidizing agent. The resistance of polypyrrole coated fiber sensor (PPy-CFS) investigated and related to coating conditions, which was controlled by adjusting the reactant concentrations and temperature effect. To improve selectivity in sensing ability of PPy-CFS some membrane such as polytetrafluoroethylene (PTFE) is used, in this work membranes are added physically to polypyrrole fiber. The morphology of the conducting film on the surface of the fibers was examined by scanning electron microscope (SEM). The SEM image shows most of the particle with a spherical shape having uniform size with diameter of around 70±5 nm.The sensing of volatile organic compounds was studied experimentally. Effects of membranes on the response behavior of PPy-CFS were investigated. The PPy-CFS had demonstrated fast response time (<1s), selectivity and sensitivity of sensors with different membranes was different for the same compounds.