Fibre-optical sensor based on fluorescent indicator for monitoring physiological pH values.

A fibre-optical sensor has been developed based on the fluorescent indicator 8-hydroxyl-1,3,6-pyrene trisulphonic acid trisodium salt (HOPSA) for monitoring physiological pH values. Dowex-1 strongly basic anion exchange resin is used as the medium to immobilise the indicator on the end of an optical fibre. Polyurethane is coated on the sensor as the permeable membrane for H+. The properties of HOPSA in solution, as well as when immobilised on the sensor, are studied and found to have the potential for monitoring physiological pH values.