Color manipulation through microchip tinting for colorimetric detection using hue image analysis.

Area of Science:

• Analytical Chemistry
• Microfluidics
• Spectroscopy

Background:

• Colorimetry using microfluidic devices offers advantages for in situ analyses with limited resources and untrained users.
• Image analysis, particularly hue analysis, provides objective colorimetric readouts but struggles with subtle or monotonal color changes.
• Existing methods are inadequate for detecting faint colorimetric reactions, limiting their application in sensitive analyses.

Purpose of the Study:

• To develop and validate novel tinting techniques for enhancing color discrimination in microfluidic colorimetric analyses.
• To improve the limit of detection for colorimetric reactions exhibiting subtle or monotonal color changes.
• To demonstrate the effectiveness of these techniques using hydrogen peroxide detection.

Main Methods:

• Implementation of three distinct tinting techniques: dyeing reagent substrates, colored printing of devices, and colored lighting during image capture.
• Utilizing hue analysis as the primary image analysis parameter.
• Applying the tinting methods to a colorimetric reaction involving hydrogen peroxide.

Main Results:

• Tinting techniques effectively shifted the background color of the reaction detection area, enhancing color contrast.
• Improved discrimination of subtle and monotonal color changes was achieved.
• The limit of detection for hydrogen peroxide was significantly improved from undetectable to 0.1 mg mL^-1.

Conclusions:

• Tinting techniques offer a robust solution for overcoming limitations in microfluidic colorimetry, particularly for reactions with subtle color changes.
• These methods enhance the sensitivity and objectivity of colorimetric analyses, expanding their applicability.
• The developed techniques show promise for rapid, on-site detection of analytes like hydrogen peroxide.