A Dean-flow-coupled interfacial viscoelastic fluid for microparticle separation applied in a cell smear method

Area of Science:

• Microfluidics
• Biotechnology
• Analytical Chemistry

Background:

• Continuous, label-free particle separation is crucial for various applications.
• Existing methods often lack efficiency or require specific labeling.
• Microfluidic devices offer precise control over particle manipulation.

Purpose of the Study:

• To develop a novel microfluidic device for continuous, label-free, and size-selective particle separation.
• To analyze the underlying mechanisms of particle migration and separation.
• To optimize device parameters for maximum separation efficiency.

Main Methods:

• A two-stage microfluidic separation process utilizing sheath flow and a non-Newtonian fluid interface.
• Analysis of force balance, including inertial lift, interfacial elastic lift, and Dean drag forces.
• Systematic variation of flow rate ratio and poly(ethylene oxide) (PEO) concentration.

Main Results:

• The first stage separates particles based on pre-focusing and interfacial forces.
• The second stage expands separation distance using a contraction-expansion structure.
• Optimal PEO concentration for peak separation distance was identified between 50-150 ppm.
• The proposed device demonstrated significant improvements in separation distance compared to existing methods.

Conclusions:

• The developed microfluidic device enables efficient, continuous, label-free, and size-selective particle separation.
• The two-stage design and controlled fluid dynamics are key to enhanced separation.
• The optimized device shows potential for sensitive and time-saving diagnostic applications, such as malignant pleural effusion diagnosis.