Enhancing Capillary-Driven Flow for Paper-Based Microfluidic Channels

Area of Science:

• Microfluidics
• Analytical Chemistry
• Materials Science

Background:

• Paper-based microfluidic devices offer low cost and simplicity but suffer from slow flow rates, sample retention, and evaporation.
• Existing designs often overlook critical limitations hindering practical applications.

Purpose of the Study:

• To develop an improved paper-based microfluidic system with accelerated liquid flow rates.
• To address limitations of sample retention, evaporation, and slow flow in paper-based devices.

Main Methods:

• A capillary-driven flow system was designed utilizing narrow gap geometry between parallel hydrophobic surfaces.
• A hydrophobic paper substrate with a hydrophilic microfluidic channel was employed, with channel sides open to air.
• The system directs liquid flow along the hydrophilic path within the gap, preventing spread onto hydrophobic regions.

Main Results:

• The closed-channel system demonstrated significantly accelerated liquid flow and increased spreading distances.
• Average flow rate increases of 200% for nanoparticle-coated paperboard and 100% for blotting papers were achieved.
• Reduced liquid drying and evaporation were observed in the proposed closed-channel configuration.

Conclusions:

• The novel paper-based microfluidic system effectively enhances liquid flow rates, enabling faster results for analytical devices.
• The design mitigates common issues like sample evaporation and retention, improving device reliability.
• This approach represents a significant advancement for low-cost, high-performance paper-based analytical devices.