Mesostructured and mesoporous metal oxide films for optical waveguide-based gas sensor application

A glass planar optical waveguide with a top layer of mesostructured or mesoporous metal oxide films, such as TiO₂, SnO₂, ZnO₂, ZrO₂, WO₃, Al₂O₃, Ta₂O₅ or Nb₂O₅, was proposed for chemical, biological and gas sensor applications. To demonstrate the application feasibility of such a composite waveguide structure, a slide glass substrate with a tin-diffused layer was dip-coated with a mesostructured hybrid film of peroxopolytungstic acid and block copolymer template. On the basis of the polarimetric interference, the resulting waveguide has been demonstrated to have a high sensitivity to ammonia in air at room temperature.