Fibre optic pH sensors prepared by sol-gel immobilisation technique

An improved fibre optic sensor with extended lifetime for pH measurements has been developed. The sensor is based on the absorbance change of organic indicators immobilised in a silica matrix coated as a thin film onto a porous glass optical fibre by the sol-gel technique. This approach has allowed the development of a highly stable, chemically durable and ruggedised fibre optic pH sensor. The sensor also has potential application in aqueous solutions at high temperatures and in those containing organic solvents.