Fiber optic oxygen sensor based on phosphorescence quenching of erythrosin B trapped in silica-gel glasses

Experimental results from a phosphorescence-based fiber-optical oxygen sensor are presented. The optical oxygen sensor module has overall dimensions of 6 x 6 x 12 mm(3). Erythrosin B immobilized in sol-gel silica, which showed strong phosphorescence quenching by oxygen, was used in the sensor probe. Oxygen sensing is effective from 0.014 to 600 mbar. On account of the long phosphorescence lifetime (similar to 0.28 ms) and high phosphorescence yield (similar to 2%) of erythrosin B in sol-gel silica at room temperature, the sensitivity of the sensor improves by a factor of 10 as compared to transition-metal complex-based optical fiber oxygen sensors. The phosphorescence quenching effect is highly selective to oxygen. The sensor is inert to commonly found gases such as nitrogen and argon, Time-decay of phosphorescence is also studied. (C) 2000 Elsevier Science B.V. All rights reserved.