Titania films optical applications

The principle and the research progress in the electrophoretic sol-gel deposition technique, which is combined sol-gel method for particle preparation and electrophoretic deposition of the sol-gel derived particles, have been described. In the principal, (1) preparation of particles by the sol-gel method, (2) deposition of particles by electrophoresis, (3) constant-voltage and constant-current deposition, and (4) solvent and electrification are introduced, hi the practical application, (1) silica thickfihns, (2) titania thick films, (3) polysilsesquioxane thick films, and (4) template-based oxide nanorods are illustrated. The electrophoretic sol-gel deposition technique offers the advantages of functional coatings in various research fields such as chemically and mechanically protective, electrically conductive, photocatalytic and bioactive materials, and it expands the possibility of fabricating optical components and ahgned micro- and nanostructures. 

Sol-gel optical sensors were developed for many different applications the determination of pH [160], measuring the absorbance of common pH indicators immobilized in thin-film silica matrices [161,162] or as a coating in fiber-optics, where the evanescent wave absorption is measured [163,164], and sensors based on fluorescent pH indicators in hybrid matrices [165,166] were also developed, showing excellent reproducibility and reversibility. Zirconia in hybrid films doped with methyl-red showed reversible response to acid and base vapors [167]. Silica-titania thin films with entrapped sensing molecules have been developed as pH sensors [168]. 

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