SENSOR PROPERTIES OF FILLED POLYMER COMPOSITES

Polymer composite films are proposed as potential materials for use in sensing the gases and vapours of organic liquids. The basic principle of the operation of the sensor relies on a marked change in the elect roconductivity of the polymer composite system when the filler concent ration is near the percolation threshold. We propose a simple model th at agrees with the experimental findings. The model assumes the format ion of a hopping conductivity infinite cluster before the true percola tion threshold of the system is reached. The conductivity response is determined by the dependence of the hopping probability on the relativ e permittivity of the polymer matrix. Humidity sensors, based on the p roposed principles, are described.