Rationalization of the behaviour of a bi-label oxygen optical sensor

An oxygen optical sensor with two luminophores embedded in a polymeric matrix was prepared. The aim was to improve oxygen quantification by optimizing precision in the whole concentration range. The two luminophores behaved as if they were independent giving to the sensing layer enlarged working range with respect to the most sensitive membrane and improved precision with respect to the less sensitive membrane. Platinum(II) 5,10,15,20-tetraphenyl-21H,23H-porphyrin, palladium(II) 5,10,15,20-tetrakis(pentafluorophenyl)-21H,23H-porphyrin, ruthenium(II) (4,7-diphenyl- 1,10- phenanthroline)3(octylsulfate)2 were used as luminophores and they were embedded either in polyvinylchloride or in polysulfone matrices. Their different life-times allowed preparing sensing membranes having optimized precision in the required concentration interval by proportioning luminophores amounts. A working curve indicated the most suitable membrane composition.