Micro hydrogen gas sensor of SnO2-Ag2O-PtOx system using the MEMS process

Thick film H₂ sensors were fabricated using SnO₂ loaded with Ag₂O and PdO_x. The composition that gave highest sensitivity for H₂ was in the weight% ratio of SnO₂:Ag₂O:PdO_x as 93:5:2. The nano-crystalline powders of SnO₂-Ag₂O-PdO_x composites synthesized by sol-gel method were screen printed on alumina substrates. Fabricated sensors were tested against gases like H₂, CH₄, C₃H₈, C₂H₅OH and SO₂. The composite material was found sensitive against H₂ at the working temperature 125degC, with minor interference of other gases. H₂ gas as low as 100 ppm can be detected by the present fabricated sensors. It was found that the sensors based on SnO₂-Ag₂O-PdO_x nanocrystalline system exhibited high performance, high selectivity and very short response time to H2 at ppm level. These characteristics make the sensor to be a promising candidate for detecting low concentrations of H₂.