Micro-humidity sensors based on a processable polyaniline blend

Polyaniline was blended with either polyvinyl alcohol or a butyl acrylate/vinyl acetate copolymer and used as a sensing medium in the construction of a resistance-based humidity sensor. The design utilised 125 μm polyester-insulated platinum wire as conducting electrodes that were dip-coated in conducting polymer. The sensors had an overall final thickness of less than 150 μm and showed high sensitivity, low resistance, and good reversibility without hysteresis. Some drift in the response was attributed to slow oxidation of the polyaniline that could be reduced by the application of appropriate barrier coatings.