A novel oxygen and/or carbon dioxide-sensitive optical transducer

Area of Science:

• Analytical Chemistry
• Sensor Technology
• Spectroscopy

Background:

• Accurate monitoring of oxygen (O(2)) and carbon dioxide (CO(2)) is crucial for environmental and physiological applications.
• Existing sensing technologies may have limitations in sensitivity, selectivity, or reversibility for simultaneous gas detection.

Purpose of the Study:

• To develop a novel, reversible transducer for the simultaneous measurement of gaseous oxygen and carbon dioxide.
• To establish a fiber optic sensing system for continuous monitoring of O(2) and CO(2) concentrations.

Main Methods:

• Employed a solution of fluorescein (FL) and potassium hydroxide in a solvent mixture of N,N'-diethylaniline (DEA) and N,N-dimethylformamide.
• Utilized changes in absorbance at specific wavelengths (400 nm for O(2), 520 nm for CO(2)) to quantify gas concentrations.
• Developed a fiber optic sensing system integrating the solvent-dye solution.

Main Results:

• Demonstrated O(2) detection based on a contact charge transfer reaction between O(2) and DEA, showing increased absorbance at 400 nm with rising O(2) concentrations (0-100%).
• Showcased CO(2) detection via a non-linear decrease in absorbance at 520 nm due to fluorescein's color change (0-10% CO(2)).
• Confirmed independent, reversible responses for both O(2) and CO(2) measurements, with O(2) following Beer-Lambert's law.

Conclusions:

• The developed fluorescein-based transducer and fiber optic system enable simultaneous, reversible measurement of O(2) and CO(2).
• The system demonstrates potential for continuous environmental and physiological monitoring within the specified concentration ranges.
• This novel approach offers a promising alternative for dual gas sensing applications.