Sol-gel processed TiO₂ films on U-shaped glass-rods as optical humidity sensor

Abstract

The fabrication and characterization of a thick-film optical humidity sensor based on the semiconducting metal-oxide TiO₂ have been described_.The sensor element consists of a thin U-shaped borosil glass-rod having different curvature with a film of TiO₂ deposited on it. The films prepared are dried and annealed at 600^oC for two hours, which make them rutile, porous and very sensitive to humidity. Both the ends of the U-shaped glass-rods are coupled to optical fibers. Light from a He-Ne laser is launched in to the sensing element through one of them. Light received from the other fibre is fed into an optical power meter. Variations in the intensity of light with changes in humidity from 5% to 95% have been recorded.