Optical fiber sensor for dual sensing of dissolved oxygen and Cu2+ ions based on PdTFPP/CdSe embedded in sol-gel matrix

A simple, low-cost technique for fabricating a plastic optical fiber sensor for the dual sensing of dissolved oxygen (DO) and Cu2+ ions is proposed. The optical fiber dual sensor consists of quantum dots (QDs) and oxygen indicator coated on the fiber end. A fluorinated xerogel doped with palladium (II) meso-tetrakis(pentafluorophenyl)porphyrin (PdTFPP) and CdSe QDs serves as the DO and Cu2+ ion sensing material. The Cu2+ ion and DO fluorescent indicators can both be excited with a 405-nm LED and the two emission wavelengths can be detected separately. The optical fiber dual sensor was tested with regard to monitoring various Cu2+ ion and DO concentrations. The attenuation of the relative luminescence intensity for Cu2+ ion sensing has a linear relationship with Cu2+ ions in the tested range. In addition, the results show that the luminescence properties of the Cu2+ ion sensor are independent of the presence of the DO sensor, and have a uniquely good linear response in the 0-10 μM range. The proposed optical fiber dual sensor can be used for the simultaneously sensing of Cu2+ ion and DO concentrations in biological, medical, and environmental applications.