The sol-gel process was used to prepare organically modified silica gl
ass in which the fluorescent pH-sensitive reagent 1-hydroxypyrene-3,6,
8-trisulfonate is entrapped. An ion-pair approach was used to incorpor
ate the hydrophilic dye in the hydrophobic glass. Good sensitivity to
gas phase carbon dioxide was observed in the 0-20% range, with rapid r
esponse. A solid-state optical sensor device is described which could
lead to thin film waveguide sensors suitable for mass production.