Hydrogen detection based on coloration of anodic tungsten oxide film

A novel method for detecting hydrogen was developed by using very thin palladium overlayer‐anodic oxide film‐tungsten sheet structure. Its optical reflectance is modulated by the presence of hydrogen in the ambient gas. The effect can be explained by the free electron modulation of optical constants of the oxide film. It is a prerequisite for fast hydrogen detection that the film consists of hydrated tungsten oxide WO3⋅H2O. The present hydrogen detector has optical readouts compatible to both thin film micro‐optics and fiber optics.