This paper presents a metal enhanced optical oxygen sensor that comprises an optical fiber coated at one end with platinum (II) meso- tetrakis(pentafluorophenyl)porphyrin (PtTFPP) and silver metal-coated nanoparticles embedded in an n-octyltriethoxysilane (Octyl-triEOS)/ tetraethylorthosilane (TEOS) composite xerogel. The sensitivity of the optical oxygen sensor is quantified in terms of the ratio IN2/IO2, where IN2 and IO2 represent the detected fluorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental results show that the oxygen sensor has a sensitivity of 167. The response time was 2.6 s when switching from pure nitrogen to pure oxygen, and 36 s when switching in the reverse direction. The experimental results show that compared to oxygen sensor based on Pt(II) complex immobilized in the sol-gel matrix, the proposed optical fiber oxygen sensor has higher sensitivity. In addition to the increased surface area per unit mass of the sensing surface, the metal-coated silica nanoparticles also increase the sensitivity because the metal-enhanced fluorescence. The proposed optical sensor has the advantages of low cost and high sensitivity for oxygen monitoring using a cheap LED as a light source.
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