Colorimetric CO₂ Indicators

Area of Science:

• Analytical Chemistry
• Materials Science
• Environmental Science

Background:

• Carbon dioxide (CO2) plays vital roles in biological and industrial processes.
• Current CO2 monitoring methods (FTIR, electrochemical) have limitations.
• Existing CO2 indicators are often water-based, limiting portability and application.

Purpose of the Study:

• To develop novel, dry CO2-sensitive materials from traditional colorimetric indicators.
• To highlight advancements in CO2 colorimetric indicator technology by the Mills group.
• To demonstrate the versatility and advantages of dry CO2 indicators over current methods.

Main Methods:

• Development of CO2-sensitive inks using pH-sensitive dyes and quaternary ammonium cations in non-aqueous polymer solutions.
• Creation of CO2-sensitive pigments by coating silica particles with CO2 inks.
• Incorporation of pigments into plastics via extrusion to form CO2-sensitive films.
• Utilizing digital camera colorimetry (DCC) for quantitative CO2 measurements.

Main Results:

• Dry CO2-sensitive inks exhibit reversible color changes in response to CO2, with tunable sensitivity.
• CO2-sensitive pigments integrated into plastics offer enhanced properties for applications like food packaging and medical diagnostics.
• Demonstrated quantitative CO2 analysis using DCC, overcoming limitations of visual assessment.
• Developed specialized indicators for temperature, fizziness in beverages, and air pressure.

Conclusions:

• Dry CO2 colorimetric indicators represent a significant advancement over traditional methods.
• These materials offer enhanced portability, cost-effectiveness, and a wider range of applications.
• Digital camera colorimetry enables quantitative analysis, increasing the commercial viability and impact of these CO2 indicators.