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Simultaneous sensing of multiple gases by a single fluorescent-based gas sensor is of utmost importance for practical applications. Such sensing is strongly hindered by cross-sensitivity effects. In this study, we propose a novel analysis method to ameliorate such hindrance. The trial sensor used here was fabricated by coating platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) and eosin-Y dye molecules on both sides of a filter paper for sensing O2 and NH3 gases simultaneously. The fluorescent peak intensities of the dyes can be quenched by the analytes and this phenomenon is used to identify the gas concentrations. Ideally, each dye is only sensitive to one gas species. However, the fluorescent peak related to O2 sensing is also quenched by NH3 and vice versa. Such cross-sensitivity strongly hinders gas concentration detection. Therefore, we have studied this cross-sensitivity effect systematically and thus proposed a new analysis method for accurate estimation of gas concentration. Comparing with a traditional method (neglecting cross-sensitivity), this analysis improves O2-detection error from −11.4% ± 34.3% to 2.0% ± 10.2% in a mixed background of NH3 and N2.

A simple signal processing, low-cost technique for the fabrication of an optical oxygen sensor based on phase shift detection is described. The sensing film is based on the oxygen-sensing dye platinum tetrakis pentrafluoropheny porphine (PtTFPP) embedded in a polymer matrix. The feasibility of coating a photodiode with the oxygen-sensing film to fabricate an optical sensing device is investigated. The optical oxygen sensor is tested with regard to monitoring excitation voltage and oxygen concentration. The experiment results show that the maximum phase difference between 0% and 100% gaseous oxygen is 26°. A preparation procedure for coating photodiodes with the oxygen-sensing film that produces repetitive and reliable sensing devices is proposed. The developed optical oxygen sensor is low-cost, has simple signal processing, and lacks optical filter elements. The proposed sensor is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optically based sensors.

This paper proposes a ratiometric optical temperature and oxygen sensor that incorporates a sol–gel matrix doped with platinum tetrakis pentafluorophenyl porphine (PtTFPP) as the oxygen-sensitive material, 7-amino-4-trifluoromethyl coumarin (AFC) as the temperature-sensing material, and rhodamine 110 (Rh110) as the temperature/oxygen-independent fluorescent dye. The feasibility of coating a color sensor with the sensing film for fabricating a ratiometric optical dual sensing device is investigated. Using an LED with a central wavelength of 405 nm as the excitation source, it is shown that the emission wavelengths of the temperature-sensitive, oxygen-sensitive, and reference dyes have no spectral overlap and therefore permit the temperature and oxygen concentration to be measured using a ratiometric-based method. The ratiometric optical dual sensor was tested with regard to monitoring various temperatures and oxygen concentrations. The results show that the luminescence properties of the temperature sensor are independent of the presence of the oxygen sensor, and have a uniquely good linear response in the 25–65 °C range. The oxygen sensing scheme presented in this work is intended for use in temperature compensation. The proposed ratiometric sensing approach suppresses the effects of spurious fluctuations in the intensity of the excitation source.

A new simple, low-cost technique for the fabrication of a portable optical sensor for the dual sensing of temperature and oxygen is described. The sensing film is based on the oxygen sensing dye platinum tetrakis pentrafluoropheny porphine (PtTFPP) and 7-amino-4-trifluoromethyl coumarin (AFC) embedded in tetraethylorthosilane (TEOS)/n-octyltriethoxysilane (Octyl-triEOS) composite xerogels. The feasibility of coating a color sensor with the sensing film to fabricate a portable optical dual sensing device is investigated. The temperature and oxygen indicators can both be excited with an LED at a wavelength 405 nm. The portable optical dual sensor has been tested with regard to monitoring different temperatures and oxygen concentrations, the oxygen response of which 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 results reveal that the portable optical oxygen sensor has a response of I N 2 / I 100 O 2 = 1.75 . In addition, our results show that the luminescence properties of the temperature sensor are independent of the presence of the oxygen sensor, and have a uniquely good linear response in the 25–65 °C range. Finally, the oxygen sensing scheme presented in this work is intended for use in temperature compensation, and the portable optical dual sensor is a cost-effective alternative to traditional electrochemical-based temperature and oxygen sensors and provides a platform for other optically based sensors.

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 to fabricate a plastic optical fiber sensor for dual sensing of temperature and oxygen has been described. The optical fiber dual sensor consists of temperature and oxygen indicators that were coated on the fiber end. A fluorinated xerogels doped with platinum tetrakis pentrafluoropheny porphine (PtTFPP) and 5(6)-carboxyfluorescein (CF) serves as the oxygen and temperature sensing material. The temperature and oxygen indicators can both be excited with an LED of 405 nm, and the two emission wavelengths can be detected separately. The optical fiber dual sensor has been tested with regard to monitoring different temperatures and oxygen concentrations. The typical Stern–Volmer plot of an optical fiber dual sensor for oxygen sensing shows linearity, and the attenuation of the relative luminescence intensity for temperature sensing also has a linear relationship with temperature in the tested range. In addition, our results show that the luminescence properties of the temperature sensor are independent of the presence of the oxygen sensor, and have a uniquely good linear response in the 25–66 °C range. Finally, the oxygen sensing scheme presented in this work is intended for use in temperature compensation, and optical fiber dual sensor can be used for the contactless-sensing of temperature and oxygen in biological, medical and environmental applications.

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 .

This paper presents a highly sensitive fiber-optic oxygen sensor. The sensor was fabricated using palladium (II) meso-tetrakis (pentafluorophenyl) porphyrin (PdTFPP) and porous silica nanoparticles embedded in a tetraethylorthosilane (TEOS)/n-octyl-triethoxysilane (Octyl-triEOS) composite xerogel present as a coating on the end of the fiber. Sensitivity is quantified in terms of the ratio IN2/IO2, where IN2 and IO2 represent the intensity of fluorescence detected in a pure nitrogen or pure oxygen environment. The experimental results reveal that this PdTFPP-doped oxygen sensor with porous silica nanoparticles has a sensitivity of IN2/I100O2 = 386. The results also show that this sensor has higher sensitivity than an oxygen sensor based on Pd(II) complex immobilized in a sol-gel matrix. Furthermore, the optical oxygen sensor yields a linear Stern–Volmer plot. The proposed optical sensor has the advantages of easy fabrication, low cost, and high sensitivity to oxygen.

This paper presents a high-sensitivity oxygen sensor that comprises an optical fibre coated at one end with tris (4, 7-diphenyl-1, 10-phenanthroline) ruthenium (II) ([Ru (dpp)3]2+) and porous silica 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 26. The experimental results show that compared to oxygen sensor based on Ru (II) complex immobilized in the sol-gel matrix, the proposed optical fibre oxygen sensor has higher sensitivity. In addition to the increased surface area per unit mass of the sensing surface, the porous silica nanoparticles increase the sensitivity because a substantial number of aerial oxygen molecules penetrate the porous silica shell. The proposed optical sensor has the advantages of easy fabrication, low cost, fast response and high sensitivity for oxygen monitoring using a cheap LED as a light source.

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 films film sequestered with luminophore platinum (II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) prepared by a sol–gel process. The composite xerogels studied are 3,3,3-trifluoropropyltrimethoxysliane (TFP-TriMOS) or n -propyltrimethoxysilane ( n -propyl-TriMOS)/tetraethylorthosilane (TEOS)/ n -octyltriethoxysilane (Octyl-triEOS). Results show that, expect for PtTFPP-doped TFP-TriMOS or n -propyl-TriMOS/TEOS/Octyl-triEOS composite xerogels show the high sensitivity and linear Stern–Volmer relationship which indicate the homogenous environment of the luminophore. The sensitivities of the two oxygen sensors are 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 results reveal that the PtTFPP-doped TFP-TriMOS/TEOS/Octyl-triEOS and n -propyl-TriMOS/TEOS/Octyl-triEOS oxygen sensors have sensitivities of 101 and 155, respectively. The experimental results confirm that the current oxygen sensors exhibit the linear Stern–Volmer plots and high-sensitive based on the oxygen indicator embedded in TFP-TriMOS or n -propyl-TriMOS/TEOS/Octyl-triEOS composite xerogels.

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.

A new, simple signal processing, low-cost technique for the fabrication of a portable oxygen sensor based on time-resolved fluorescence is described. The sensing film uses the oxygen sensing dye platinum meso-tetra (pentfluorophenyl) porphyrin (PtTFPP) embedded in a polymer matrix. The experimental results reveal that the PtTFPP-doped oxygen sensor has a sensitivity of 2.2 in the 0-100% range. A preparation procedure for coating the photodiodes with the oxygen sensor film that produces repetitive and reliable sensing devices is proposed. The developed time-resolved optical oxygen sensor is portable, low-cost, has simple signal processing, and lacks optical filter elements. It is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optical based sensors.

A new, simple signal processing, low-cost technique for the fabrication of a portable oxygen sensor based on time-resolved fluorescence is described. The sensing film uses the oxygen sensing dye platinum meso-tetra (pentfluorophenyl) porphyrin (PtTFPP) embedded in a polymer matrix. The ratio τ0/τ100 measures sensitivity of the sensing film, where τ0 and τ100 represent the detected fluorescence lifetimes from the sensing film exposed to 100% nitrogen and 100% oxygen, respectively. The experimental results reveal that the PtTFPP-doped oxygen sensor has a sensitivity of 2.2 in the 0%–100% range. A preparation procedure for coating the photodiodes with the oxygen sensor film that produces repetitive and reliable sensing devices is proposed. The developed time-resolved optical oxygen sensor is portable, low-cost, has simple signal processing, and lacks optical filter elements. It is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optical based sensors.

An optical sensor for the dual sensing of oxygen (Osub2/sub) and carbon dioxide (COsub2/sub) based on sensing films coated on filter paper is proposed. Ethyl cellulose (EC) doped with platinum(II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) and 7-amino-4-trifluoromethyl coumarin serve as the oxygen sensing material and reference blue emission dye for the pH indicator, respectively. The COsub2/subsensing layer includes the pH-sensitive fluorescent indicator 1-hydroxy-3,6,8-pyrenetrisulfonic acid trisodium salt immobilized within the EC. The Osub2/sub- and COsub2/sub-sensitive materials can both be excited with a 405 nm LED, and the two emission wavelengths can be detected separately. The experimental result reveals that the optical Osub2/suband COsub2/subsensors have sensitivities of IsubNsub2/sub/sub/Isub100%Osub2/sub/sub=22.8 and IsubNsub2/sub/sub/Isub100%COsub2/sub/sub=3.6, respectively. The response times of the optical Osub2/subsensor were 15 s upon switching from nitrogen to Osub2/suband 41 s when moving from Osub2/subto nitrogen (Nsub2/sub). The response times of the optical COsub2/subsensor were 7 s upon switching from 100% Nsub2/subto 100% COsub2/suband 39 s when moving from 100% COsub2/subto 100% Nsub2/sub. The proposed optical dual sensor can be used for the simultaneous sensing of Osub2/suband COsub2/subconcentrations in environmental applications.

This paper presents a high-sensitivity oxygen sensor that comprises an optical fiber coated at one end with tris(4,7-diphenyl-1,10-phenanthroline) ruthenium(II) ([Ru(dpp)3]2+) and porous silica 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 26. The response time was 2 s when switching from pure nitrogen to pure oxygen, and 7.7 s when switching in the reverse direction. The experimental results show that compared to an oxygen sensor based on Ru(II) complex immobilized in the solgel 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 porous silica nanoparticles increase the sensitivity because a substantial number of aerial oxygen molecules penetrate the porous silica shell. The proposed optical sensor has the advantages of easy fabrication, low cost, fast response, and high sensitivity for oxygen monitoring using a cheap LED as a light source.

A simple low-cost technique for the fabrication of portable optical oxygen sensors is described. The sensing film is based on the oxygen sensing dye tris(4,7-diphenyl-1,10-phenanthroline)ruthenium(II) {[Ru(dpp)3] 2 + } and dye-entrapped core-shell silica nanoparticles embedded in a sol-gel matrix. The feasibility of coating a photodiode with the oxygen sensing film to fabricate a portable optical sensing device is investigated. The sensitivity of the sensor is quantified in terms of the ratio IN2 /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 portable optical oxygen sensor has sensitivity of 41. The sensor exhibits a linear response for oxygen concentrations in the range 0 to 60%. A preparation procedure for coating photodiodes with the oxygen film that produces repetitive and reliable sensing devices is proposed. The developed optical oxygen sensor is portable, low-cost, highly sensitive, and lacks optical filter elements. The proposed sensor is a cost-effective alternative to traditional electrochemical-based oxygen sensors and provides a platform for other optically based sensors.

Oxygen and carbon dioxide sensors are involved in many chemical and biochemical reactions. Consequently, considerable efforts over years have been devoted to discover and improve suitable techniques for measuring gas concentrations by optical fiber sensors. Optical gas sensors consist of a gas-sensitive dye entrapped in a matrix with a high permeability to gas. With such sensors, gas concentration is evaluated based upon the reduction in luminescence intensity caused by gas quenching of the emitting state. However, the luminescence quenching effect of oxygen is highly sensitive to temperature. Thus, a simple, low-cost plastic optical fiber sensor for dual sensing of temperature and oxygen is presented. Also, a modified Stern-Volmer model is introduced to compensate for the temperature drift while the temperature is obtained by above dual sensor. Recently, we presented highly-sensitive oxygen and dissolved oxygen sensors comprising an optical fiber coated at one end with platinum (II) meso-tetrakis(pentafluorophenyl)porphyrin (PtTFPP) and PtTFPP entrapped core-shell silica nanoparticles embedded in an n-octyltriethoxysilane(Octyl-triEOS)/tetraethylorthosilane (TEOS) composite xerogel. Also, two-dimensional gas measurement for the distribution of chemical parameters in non-homogeneous samples is developed and is of interest in medical and biological researches.