A SO2 fiber optic sensor was prepared It consists of combination of a pH optic sensor based on absorption of immobilized dye (bromphenol blue, l = 624 nm, or bromcresol green, l = 600 nm) and a piece of silicone rubber membrane with a reservoir of HSO3- solution When SO2 diffuses across the membrane, the pH of internal HSO3- solution is changed. The observed pH change is a measure of the total SO2 in the sample. Agreement between theory and experiment is good. The response range depends on the concentration of HSO3- in the internal solution and the pH range to which the pH optic sensor can respond.

Key words: SULFUR DIOXIDE, OPTICAL WAVEGUIDE FIBER, SENSORS, GAS SENSITIVE ELECTRODE, OPTICAL FIBER DEVICES, DYE ABSORPTION