Continuous particle separation in spiral microchannels using Dean flows and differential migration.

Area of Science:

• Biomedical Engineering
• Environmental Science
• Fluid Dynamics

Background:

• Microparticle separation is crucial for biomedical and environmental applications.
• Existing methods often require active components or complex fabrication.
• A need exists for efficient, passive microfluidic separation techniques.

Purpose of the Study:

• To develop and demonstrate a passive microfluidic device for size-based microparticle separation.
• To utilize spiral microchannel geometry and Dean forces for differential particle migration.
• To achieve complete separation of microparticles in a continuous flow system.

Main Methods:

• Design of a passive microfluidic device with a 5-loop spiral microchannel (100 µm wide, 50 µm high).
• Exploitation of inertial lift, viscous drag, and Dean forces for particle manipulation.
• Experimental validation using particles of 7.32 µm and 1.9 µm at a Dean number of 0.47.

Main Results:

• Successful, complete separation of 7.32 µm and 1.9 µm particles.
• Demonstration of Dean forces' dual role in focusing larger particles and transposing smaller ones.
• Formation of two distinct particle streams collected at separate outputs.

Conclusions:

• The spiral microfluidic device offers an effective method for passive, size-based microparticle separation.
• The device's simple planar structure facilitates fabrication and integration into micro total analysis systems (µTAS) and lab-on-a-chip (LOC) devices.
• This technology holds promise for continuous filtration and separation applications in various fields.