Hypersensitive H sensor based on polymer planar Bragg gratings coated with Pt-loaded WO-SiO.

This Letter demonstrates a novel, to the best of our knowledge, hydrogen sensor based on a polymer planar Bragg grating coated with Pt-loaded -. The reflected Bragg signal shows a distinct peak splitting correlated to substrate anisotropies originating from the injection molding process. Especially at low concentrations, both sensing peaks exhibit an outstanding response to the heat generated by the exothermic reaction between hydrogen molecules and coating. Thereby, a hydrogen volume ratio of 50 ppm leads to a Bragg wavelength shift of -37, which yields an outstandingly low detection limit of only 5 ppm in air. Thus, functionalized polymer planar Bragg gratings are eminently suitable for leak detection applications.