Centrifugal Paperfluidic Platform for Accelerated Distance-Based Colorimetric Signal Readout

Area of Science:

• Analytical Chemistry
• Materials Science
• Biomedical Engineering

Background:

• Paper-based analytical devices (PADs) commonly use distance-based readout for user-friendly colorimetric assays.
• Traditional methods require precise sample volumes, limiting speed and accessibility.
• Integrating PADs with centrifugal platforms offers potential for improved performance.

Purpose of the Study:

• To develop centrifugally assisted distance-based PADs (CD-PADs) for affordable, rapid, and sample volume-independent colorimetric assays.
• To demonstrate the fabrication and optimization of CD-PADs using computer-controlled techniques and a low-cost centrifugal platform.
• To validate the performance of CD-PADs using a colorimetric nickel ion (Ni2+) assay.

Main Methods:

• Fabrication of PADs using computer-controlled print, cut, and laminate (PCL) techniques.
• Construction of an inexpensive centrifugal platform using a recycled DVD player and an Arduino microcomputer.
• Optimization of assay protocols, including rotational velocity and time, for maximum dynamic range and reproducibility.
• Demonstration using a colorimetric Ni2+ assay for naked-eye detection.

Main Results:

• CD-PADs eliminate the need for micropipets, reducing assay time and complexity.
• Optimized protocols yielded reproducible sample volume metering with a coefficient of variation of 3.62%.
• The Ni2+ assay achieved naked-eye detection within 1.5 minutes with a limit of detection (LOD) of 44.1 ng, the lowest reported for distance-based Ni2+ assays.

Conclusions:

• CD-PADs provide an affordable, rapid, and user-friendly platform for colorimetric analysis.
• The developed system demonstrates high sensitivity and reproducibility for metal ion detection.
• This technology has potential for mass production and widespread application in point-of-care diagnostics and environmental monitoring.