Eco-friendly pH detecting paper-based analytical device: Towards process intensification.

Area of Science:

• Analytical Chemistry
• Materials Science
• Biotechnology

Background:

• Traditional pH measurement methods can be expensive and require specialized equipment.
• There is a growing need for low-cost, portable, and sustainable sensing technologies.
• Natural dyes offer a promising alternative to synthetic indicators for chemical sensing applications.

Purpose of the Study:

• To develop a miniaturized, paper-based pH detection platform utilizing natural dye from red cabbage.
• To optimize the fabrication and experimental parameters for accurate pH sensing.
• To validate the performance of the developed sensor against standard pH measurement techniques.

Main Methods:

• Extraction of natural dye from red cabbage (Brassica oleracea).
• Fabrication of a patterned paper-based substrate using a punching machine.
• Quantitative assessment of pH using digital image analysis and CIEL*a*b* color space models.
• Optimization of experimental parameters and regression analysis to identify the best signal readout (a* parameter).

Main Results:

• The a* parameter in the CIEL*a*b* color space showed excellent correlation with pH (R² = 0.9754).
• The paper-based sensor accurately quantified pH in the range of 1-12.
• Results from real test samples validated against a standard pH meter demonstrated high accuracy.
• The device requires minimal reagent and sample volumes, enabling in situ measurements.

Conclusions:

• A simple, eco-friendly, and cost-effective paper-based pH sensor was successfully developed using red cabbage dye.
• The developed sensor offers a reliable and quantitative method for pH detection suitable for in situ applications.
• This approach supports the development of sustainable and intensified chemical sensor technologies.