Paper-Based Microfluidics Perform Mixing Effects by Utilizing Planar Constricted-Expanded Structures to Enhance...

Area of Science:

• Microfluidics
• Chemical Engineering
• Materials Science

Background:

• Paper-based microfluidic devices offer a low-cost platform for various applications.
• Efficient mixing remains a challenge in passive microfluidic systems.
• Enhancing chaotic advection is key to improving mixing performance.

Purpose of the Study:

• To design and fabricate planar constricted-expanded structures for paper-based microfluidic channels.
• To evaluate the mixing performance of different constricted-expanded channel designs.
• To investigate the effect of these structures on flow patterns and chaotic advection.

Main Methods:

• Utilized chromatography paper and a solid-wax printer to fabricate paper-based microfluidic devices.
• Designed and tested three distinct constricted-expanded structures: zigzag, crossed, and curved channels.
• Employed numerical simulations to analyze mixing mechanisms and flow dynamics.

Main Results:

• Experimental results demonstrated significant improvements in mixing indices across all tested structures compared to straight channels.
• Mixing indices increased from 20.1% (unmixed) to 34.5% (straight), 84.3% (zigzag), 87.3% (curved), and 92.4% (cross-shaped).
• Numerical simulations showed good agreement with experimental data, with variations between 1.0% and 11.0%.

Conclusions:

• Planar constricted-expanded structures effectively enhance chaotic advection and mixing in paper-based microfluidic devices.
• The cross-shaped and curved channel designs exhibited the highest mixing efficiencies.
• These passive paper-based mixers hold promise for advancing microfluidic applications.