A wet-chemical process to form palladium oxide sensitiser layer on thin film zinc oxide based LPG sensor

The liquid petroleum gas (LPG) sensitivity characteristics of zinc oxide (ZnO) films have been studied for an optimised level of Pd loading. The sensor element comprises of a layer of chemically deposited ZnO on which an overlayer of palladium (Pd) sensitiser was formed by a chemical dipping technique. The room temperature resistance of the film was found to be a sensitive function of the quantity of palladium loading, which could be optimised for stable and reproducible sensor properties. The sensor characteristics that are dependent also on the operating temperature could be optimised at around 250 °C. A sensitivity of 88% was observed in presence of 1.6 vol.% LPG in air at this optimum temperature with reasonably fast response and recovery times.