Abstract
A fiber optic pH sensor has been fabricated using 1-(2-pyridylazo)-2-naphthol entrapped in an ammonia catalyzed silica sol-gel film coated on glass substrate by dip-coating. The sensor was fixed at the end of an optical fiber. The sensor showed pH sensitivity when dipped into liquids of different pH. Linear and reproducible responses were obtained in standard buffer solutions in the pH range of 7.2-8.4 which encompasses the clinically-relevant range. The effects of interferences on the determination of pH were also investigated. The sensor was successfully applied to the determination of pH in various pH buffer solutions.