Highly sensitive optical fiber oxygen sensor using Pt(II) complex embedded in sol–gel matrices

A simple, low-cost technique for fabrication of an optical fiber oxygen sensor is described. The technique is based on coating the end of an optical fiber with a microporous film prepared by a sol–gel process. A platinum complex, platinum tetrakis pentrafluoropheny porphine (PtTFPP) or platinum octaethylporphine (PtOEP), is trapped in the microporous film. In this sensor configuration, the complex is excited by the 380 nm radiation and guided by an optical fiber. As a result, the I0/I100 values of the PtTFPP or PtOEP doped in n-Octyltriethoxysilane (Octyl-triEOS)/tetraethylorthosilane (TEOS) composite xerogels are estimated to be 22.31 and 47.84, respectively. Also, the typical Stern–Volmer plot shows a very good linearity. The response time of the PtTFPP doped in Octyl-triEOS/TEOS composite xerogels is 0.6 s upon switching from nitrogen to oxygen and 5 s from oxygen to nitrogen. In addition, the response time of the PtOEP doped in Octyl-triEOS/TEOS composite xerogels is 0.7 s upon switching from nitrogen to oxygen and 14 s from oxygen to nitrogen. These results indicate that the optical fiber oxygen sensors based on the platinum complexes exhibit greater sensitivity, stability and faster response time as compared to the existing ones.