Optimization of Printed Polyaniline Composites for Gas Sensing Applications

Gas Sensor with Different Morphology of PANI Layer

This work presents the design of a polymer-film-based sensor for gas detection. Different types of polyaniline are used as active layers. The advantages of resistive sensors with PANI layers are easy preparation and low production cost. At room temperature, polymer films have a high sensitivity to gas concentrations. The developed sensor works on the idea of electrical resistance shifting with gas concentration. Three different polymerization solutions are employed to synthesize the polyaniline (PANI) active layers (aqueous solution, sulfuric acid solution, and acetic acid solution). Active layers are evaluated in a controlled environment for their ability to detect ammonia, carbon monoxide, nitrogen monoxide, acetone, toluene, and relative humidity in synthetic air. PANI layers polymerized in acetic acid solutions exhibit good sensitivity toward ammonia.

Analysis of the Resistance Change of Chemosensitive Layers to the Presence of Ammonia Vapors under Variable Conditions of Air Temperature and Humidity

The developed chemosensitive layers consisted of multi-walled carbon nanotubes (MWCNTs), reduced graphene oxide (rGO), and a conductive polymer (polyaniline-PANI) in a polymeric matrix (a polystyrene solution in methylene chloride). The layers were challenged with a test gas to determine the optimum variant in terms of sensitivity to the selected analyte and the repeatability of results. In terms of individual components, the greatest percentage change in resistance (32%) and the best repeatability were found for chemosensitive layers containing a PANI salt in the polymeric matrix. Even greater changes in resistance were exhibited by sensors containing more than one active component in the matrix: 45% for PANI + MWCNTs and 75% for PANI + rGO. The presented method of thin-layer deposition was shown to be suitable for the production of sensitive and functional sensors of ammonia vapors. The developed sensors were characterized by high repeatability and sensitivity to a harmful substance that constitutes an inhalation hazard to workers. The sensors were also analyzed for their durability and recovery as well as the ability to function under varying temperature and humidity conditions.