Flow Injection Small-volume Fiber-optic pH Sensor Based on Evanescent Wave Excitation and Fluorescence Determination

Xiong, Yan; Huang, Ying; Ye, Zhongbin; Guan, Yafeng

doi:10.1007/s10895-010-0790-2

Cited by 14 publications

(8 citation statements)

References 36 publications

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“…1208 A small-volume fiberoptic pH sensor based on evanescent wave excitation and fluorometric detection was adapted such that it can be placed in a FIA analyzer. 1209 The sensor was fabricated by inserting a declad fiber into a transparent capillary tube. The microchannel between the optical fiber and the capillary inner wall acts as the flow cell.…”

Section: Ph Sensors As Transducers In Chemical Sensorsmentioning

confidence: 99%

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

2020

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This is the first comprehensive review on methods and materials for use in optical sensing of pH values and on applications of such sensors. The Review starts with an introduction that contains subsections on the definition of the pH value, a brief look back on optical methods for sensing of pH, on the effects of ionic strength on pH values and p K a values, on the selectivity, sensitivity, precision, dynamic ranges, and temperature dependence of such sensors. Commonly used optical sensing schemes are covered in a next main chapter, with subsections on methods based on absorptiometry, reflectometry, luminescence, refractive index, surface plasmon resonance, photonic crystals, turbidity, mechanical displacement, interferometry, and solvatochromism. This is followed by sections on absorptiometric and luminescent molecular probes for use pH in sensors. Further large sections cover polymeric hosts and supports, and methods for immobilization of indicator dyes. Further and more specific sections summarize the state of the art in materials with dual functionality (indicator and host), nanomaterials, sensors based on upconversion and 2-photon absorption, multiparameter sensors, imaging, and sensors for extreme pH values. A chapter on the many sensing formats has subsections on planar, fiber optic, evanescent wave, refractive index, surface plasmon resonance and holography based sensor designs, and on distributed sensing. Another section summarizes selected applications in areas, such as medicine, biology, oceanography, bioprocess monitoring, corrosion studies, on the use of pH sensors as transducers in biosensors and chemical sensors, and their integration into flow-injection analyzers, microfluidic devices, and lab-on-a-chip systems. An extra section is devoted to current challenges, with subsections on challenges of general nature and those of specific nature. A concluding section gives an outlook on potential future trends and perspectives.

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Section: Ph Sensors As Transducers In Chemical Sensorsmentioning

confidence: 99%

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

2020

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“…The surface interaction process between MB and silanol (SiOH) groups is discussed and the adsorption mechanism is proposed for the MB adsorption on silica interface. Compared with the traditional evanescent wave sensor fabricated for species determination reported by some research groups − and our lab, − this work is a new attempt to apply total internal reflection-induced evanescent wave to interfacial adsorption monitoring.…”

Section: Introductionmentioning

confidence: 99%

Real-Time Monitoring of Azo Dye Interfacial Adsorption at Silica–Water Interface by Total Internal Reflection-Induced Surface Evanescent Wave

et al. 2018

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An interface research method based on total internal reflection induced evanescent wave (TIR-EW) is developed to monitor the adsorption behavior of azo dye at the silica-water interface. The monitoring system is constructed by employing silica optical fiber (SOF) as both charged substrate for dye adsorption and light transmission waveguide for evanescent wave production. According to the change of evanescent wave intensity and followed by Beer's law, the methylene blue (MB) adsorption behavior can be real-time monitored at the silica-water interface. Langmuir adsorption model and pseudo-first-order model are applied to obtain the related thermodynamic and kinetic data. The adsorption equilibrium constant ( K) and adsorption free energy (Δ G) of MB at the silica-water interface are determined to be (3.3 ± 0.5) × 10 M and -25.7 ± 1.7 kJ mol. Meanwhile, this method is highlighted to isolate elementary processes of adsorption and desorption under steady-state conditions, and gives adsorption rate constant ( k) and desorption rate constant ( k) of 8585 ± 19.8 min and 0.26 ± 0.0006 min for 15 r/min flow rate. The surface interaction process is revealed and adsorption mechanism is proposed, indicating MB first adsorbed on Si-O sites through electrostatic attraction and then on Si-OH sites through hydrogen bond with increasing MB concentrations. Our findings from this study provided molecular-level interpretation of azo dye adsorption at silica-water interface, and the results provide important insight into how MB adsorption can be controlled at the interface.

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“…The most familiar optical methods applied to measure pH and dissolved oxygen are fluorescence, absorbance, reflectance and EW attenuation [15][16][17]. The sensing membrane is prepared by using many immobilization techniques, e.g.…”

Section: Introductionmentioning

confidence: 99%

Sol–gel based portable optical sensor for simultaneous and minimal invasive measurement of pH and dissolved oxygen

Deepa¹,

Ganesh²

2015

Measurement

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Flow Injection Small-volume Fiber-optic pH Sensor Based on Evanescent Wave Excitation and Fluorescence Determination

Cited by 14 publications

References 36 publications

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

Optical Sensing and Imaging of pH Values: Spectroscopies, Materials, and Applications

Real-Time Monitoring of Azo Dye Interfacial Adsorption at Silica–Water Interface by Total Internal Reflection-Induced Surface Evanescent Wave

Sol–gel based portable optical sensor for simultaneous and minimal invasive measurement of pH and dissolved oxygen

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