Sheathless separation of microalgae from bacteria using a simple straight channel based on viscoelastic microfluidics

Area of Science:

• Biotechnology
• Microfluidics
• Cell Separation

Background:

• Microalgae are vital for renewable energy, food, and materials.
• Contamination by bacteria necessitates efficient purification methods for microalgae cultivation.
• Existing separation techniques can be complex or inefficient.

Purpose of the Study:

• To develop a simple, sheathless, and efficient method for separating microalgae (Chlorella) from bacteria (Bacillus Subtilis).
• To leverage the viscoelastic properties of a medium for size-based cell separation.
• To establish a continuous and user-friendly purification process.

Main Methods:

• Utilized a straight microchannel and the viscoelasticity of a fluid medium.
• Employed fluorescent microparticles (1 μm and 5 μm) to optimize separation conditions.
• Compared separation in Newtonian vs. viscoelastic fluids and across different channel aspect ratios.
• Demonstrated separation of actual microalgae and bacteria cells.

Main Results:

• Achieved up to 98.28% removal of 1 μm particles and 93.85% separation efficiency for 5 μm particles.
• Successfully separated microalgae from bacteria with 92.69% bacteria removal and 100% microalgae separation efficiency.
• Validated the continuous, sheathless separation of microalgae from bacteria using viscoelastic microfluidics.

Conclusions:

• Viscoelastic microfluidics offers a highly effective and simple method for microalgae-bacteria separation.
• This technique demonstrates potential for continuous, high-purity cell purification.
• The method is adaptable for separating other cell types, including mammalian cells.