Optical fiber dissolved oxygen sensor based on Pt(II) complex and core-shell silica nanoparticles incorporated with sol–gel matrix

This paper presents a highly sensitive dissolved oxygen sensor comprising an optical fiber coated at one end with core-shell silica nanoparticles and platinum(II) meso-tetrakis (pentafluorophenyl) porphyrin (PtTFPP) embedded in an n-octyltriethoxysilane (Octyl-triEOS)/tetraethylorthosilane (TEOS) composite xerogel. The sensitivity of optical fiber dissolved oxygen sensor is quantified in terms of the ratio I0/I100, where I0 and I100 represent the detected fluorescence intensities in fully deoxygenated and fully oxygenated water, respectively. The experimental results show that the optical fiber dissolved oxygen sensor has a sensitivity of approximately 117 in the range 0–40 mg/L of dissolved oxygen concentrations. The experimental results show that as compared to the other optical dissolved oxygen sensors based on Pt(II) or Ru(II) complexes, the proposed optical fiber dissolved oxygen sensor has the highest sensitivity. In addition to the increased surface area per unit mass in the sensing surface, the dye entrapped in the core of silica nanoparticles also play an important role in the increased sensitivity because of the penetration of substantial amount oxygen molecules through the porous silica shell.