Colorimetry-based System for Gaseous Carbon Dioxide Detection

• Main Authors: João Mendes, Luís Coelho, Carlos Manuel de Melo Pereira, Pedro Jorge
• Format: Article
• Language: English
• Published: Universidade do Porto 2020-11-01
• Series: U.Porto Journal of Engineering
• Subjects: carbon dioxide detection; colorimetric membrane; polymerization; optical fiber
• Online Access: https://journalengineering.fe.up.pt/article/view/641

The study of sensing materials to the detection of carbon dioxide (CO2) was achieved using p-nitrophenol (pNPh) as a colorimetric indicator. The sensing material was polymerized (NPLn), functionalized with 3-triethoxysilyl propyl isocyanate (IPTES) which sensitivity was tested in the form of a membrane as is and encapsulated in hollow silica nanoparticles. The sensing membranes were tested in a closed gas system comprising very precise flow controllers to deliver different concentrations of CO2 (vs. N2). The combination of the sensing membranes with multimode optical fibers and a dual-wavelength diode (LED) allows the measurement of the CO2 through the analysis of the induced absorbance changes with a self-referenced ratiometric scheme. The analysis of the sensing materials have shown significant changes in their chemical and physical properties and the results attest these materials with a strong potential for assessing CO2 dynamics in environmental, medical, and industrial applications.