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A simple, low cost technique to fabricate a ratiometric optical fiber dissolved oxygen sensor has been presented. The ratiometric optical fiber dissolved oxygen sensor comprising a plastic optical fiber coated at one end with Pd(II)/CdSe QDs or Pt(II)/CdSe QDs embedded in sol–gel matrix. Using an LED with a central wavelength of 405 nm as an excitation source, it is shown that the emission wavelengths of the oxygen-sensitive dye (PdTFPP, PdTCPP, PtTFPP and PtOEP) and the reference CdSe QDs have no spectral overlap and therefore permit the dissolved oxygen concentration to be measured using a ratiometric-based method. The sensitivity of optical fiber dissolved oxygen sensor is quantified in terms of the ratio I0/I100, where I0 and I100 represent the detected luminescence intensities in fully-deoxygenated and fully-oxygenated water, respectively. The experimental results show that the sensitivities of the ratiometric optical fiber dissolved oxygen sensors are estimated to be 21.7 for PdTFPP-doped sensor, 7.4 for PdTCPP-doped sensor, 6.5 for PtTFPP-doped sensor and 9.2 for PtOEP-doped sensor. The ratiometric sensing approach presented in this study has the advantage of suppressing the effects of spurious fluctuations in the intensity of the excitation source and optical transmission properties of the optic fiber.

A simple, low-cost technique for fabrication of highly sensitive fiber-optic oxygen sensor is described. An organically modified silicate (ORMOSIL) as a matrix for the fabrication of oxygen sensing film was produced. The technique is based on coating the end of a plastic optical fiber with ormosil composite xerogel film sequestered with luminophore palladium (II) meso-tetra(4-carboxyphenyl)porphyrin (PdTCPP) prepared by a sol–gel process. The composite xerogel studied is tetraethylorthosilane (TEOS)/n-octyltriethoxysilane (Octyl-triEOS). Result shows that, expect for PdTCPP-doped TEOS/Octyl-triEOS composite xerogel show the high sensitivity and linear Stern–Volmer relationship which indicate the homogenous environment of the luminophore. The sensitivity of the optical oxygen sensor is quantified in terms of the ratio I N2 / I O2 , where I N2 and I O2 represent the detected fluorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental result reveals that the PdTCPP-doped TEOS/Octyl-triEOS oxygen sensor has sensitivity of 153.

A simple, low-cost technique for fabrication of high performance optical fiber oxygen sensor is described. An organically modified silicate (ORMOSIL) as a matrix for the fabrication of oxygen sensing film was produced. The technique is based on coating the end of an optical fiber with ormosil composite xerogel film sequestered with luminophore palladium (II) meso-tetrakis(pentafluorophenyl)porphyrin (PdTFPP) prepared by a sol–gel process. The composite xerogel studied is n-propyltrimethoxysilane (n-propyl-TriMOS)/tetraethylorthosilane (TEOS)/n-Octyltriethoxysilane (Octyl-triEOS). Result shows that, expect for PdTFPP-doped n-propyl-TriMOS/TEOS/Octyl-triEOS composite xerogel shows a high sensitivity and linear Stern–Volmer relationship which indicates the homogenous environment of the luminophore. The sensitivity of the optical oxygen sensor is quantified in terms of the ratio I N 2 / I O 2 , where I N 2 and I O 2 represent the detected phosphorescence intensities in pure nitrogen and pure oxygen environments, respectively. The experimental result reveals that the PdTFPP-doped n-propyl-TriMOS/TEOS/Octyl-triEOS oxygen sensor has sensitivity of I N 2 / I 100 O 2 = 263 .