An Open-Type Crossflow Microfluidic Chip for Deformable Droplet Separation Driven by a Centrifugal Field

Area of Science:

• Microfluidics
• Biotechnology
• Chemical Engineering

Background:

• Microfiltration processes often suffer from clogging and inefficiency.
• Existing droplet sorting methods may require external pumps and can be prone to contamination.

Purpose of the Study:

• To develop and validate a novel centrifugal microfluidic chip for pump-free, high-throughput droplet sorting.
• To investigate the influence of geometric parameters and rotational speed on droplet separation performance.
• To establish a theoretical model for predicting critical droplet size during centrifugal separation.

Main Methods:

• Fabrication of a wedge-shaped inlet weir-type microfluidic chip from PMMA.
• Utilizing centrifugal force, shear stress, and Dean vortices for crossflow separation.
• Systematic investigation of water-in-oil emulsions with varying droplet sizes (0-400 μm).
• Development of a theoretical model based on force balance (centrifugal, viscous, pressure, surface tension).

Main Results:

• The microfluidic chip successfully sorted droplets from 0 to 400 μm at 200 rpm.
• Achieved a maximum sorting efficiency of 72% and a cutoff accuracy of 98.2%.
• Demonstrated pump-free operation and confirmed the absence of cross-contamination via fluorescence analysis.

Conclusions:

• The developed centrifugal microfluidic chip offers an efficient, contamination-free solution for droplet sorting.
• The structure-guided design leverages fluid dynamics under centrifugal fields for selective separation.
• Potential applications include biomedical diagnostics, drug screening, and other fields requiring precise droplet manipulation.