Optical properties of sol-gel coatings for fiberoptic sensors

Sol-gel-derived materials can be exploited for the construction of various optoelectronic devices, including sensors optodes and their protective layers, as well as other kinds of coatings. Different types of materials were studied: silica sol-gel matrices made from silica solutions with water or alcohol as solvents. The samples were prepared in the form of single layer films. The films were deposited on glass surfaces. The porous structure of sol-gels layers was examined as well as the transmittance spectra, which were measured in the visible and UV regions. A strong influence of the solvent type on the material optical properties was noted. Alcohol-based samples showed stable homogenous structures, with no cracking. However, the water-based samples demonstrated higher transmittance in the visible region. The obtained results can serve as a basis for choosing a suitable layer when constructing optical sensors or coatings. (C) 2002 Elsevier Science B.V. All rights reserved.