Hydrogen selective gas sensor in humid environment based on polymer coated nanostructured-doped tin oxide

Nanocrystalline indium oxide-doped tin oxide thin film sensors have been synthesized using sol–gel dip-coating technique. The sensors were spin-coated with three different types of polymer namely polymethyl methacrylate (PMMA), poly-perfluorobutenyl vinyl ether (Cytop), fluoropolymer (Fluoropel). The room temperature sensor characteristics (response time, electrical response and recovery time) of the three sensors with different polymer coating were compared at hydrogen concentrations of 600, 1500, 6000 and 15,000 ppm and at two different humidity levels of 14% and 65%. It was found that the polymer coating preserves the selective sensing property of indium oxide-doped tin oxide even at high humidity. The response kinetics of the sensors with different coatings has been compared.