Hypersensitive H2 sensor based on polymer planar Bragg gratings coated with Pt-loaded WO3-SiO2

This Letter demonstrates a novel, to the best of our knowledge, hydrogen sensor based on a polymer planar Bragg grating coated with Pt-loaded WO3-SiO2. The reflected. Bragg signal shows a distinct peak splitting correlated. to substrate anisotropies originating from the injection molding process. Especially at low H-2 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 pm, which yields an outstandingly low detection limit of only 5 ppm H-2 in air. Thus, functionalized polymer planar Bragg gratings are eminently suitable for H-2 leak detection applications. (C) 2020 Optical Society of America