CHARACTERISTICS OF DYE-IMPREGNATED TETRAETHYLORTHOSILANE (TEOS) DERIVED SOL-GEL COATINGS

An investigation has been carried out on a cross-comparison study into several sol-gel coatings, impregnated with a pH-sensitive fluorescent dye, to determine their optimum characteristics, with the aim of thei r application as thin film sensor elements in fibre optic chemical sen sors. In this test of the coatings, they were applied to standard, cle aned microscope slides and several characteristics, such as the abilit y of the sol to wet the glass substrate and the optical clarity of the subsequent coating were investigated and found to depend mainly on th e water: tetraethylorthosilane (H2O:TEOS) ratio used in their preparat ion but also on the extent of aging and the level of catalyst used. It was found that thicker coatings could be created through the use of s uitable chemical additives in the preparation process.