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

Yuan, Dan, Zhao, Qianbin, Yan, Sheng, Tang, Shi Yang, Zhang, Yuxin, Yun, Guolin, Nguyen, Nam Trung, Zhang, Jun, Li, Ming and Li, Weihua (2019) Sheathless separation of microalgae from bacteria using a simple straight channel based on viscoelastic microfluidics. Lab on a Chip, 19 (17), 2811-2821. (doi:10.1039/c9lc00482c).

Abstract

Microalgae cells have been recognized as a promising sustainable resource to meet worldwide growing demands for renewable energy, food, livestock feed, water, cosmetics, pharmaceuticals, and materials. In order to ensure high-efficiency and high-quality production of biomass, biofuel, or bio-based products, purification procedures prior to the storage and cultivation of the microalgae from contaminated bacteria are of great importance. The present work proposed and developed a simple, sheathless, and efficient method to separate microalgae Chlorella from bacteria Bacillus Subtilis in a straight channel using the viscoelasticity of the medium. Microalgae and bacteria migrate to different lateral positions closer to the channel centre and channel walls respectively. Fluorescent microparticles with 1 μm and 5 μm diameters were first used to mimic the behaviours of bacteria and microalgae to optimize the separating conditions. Subsequently, size-based separation in Newtonian fluid and in viscoelastic fluid in straight channels with different aspect ratios was compared and demonstrated. Under the optimal condition, the removal ratio for 1 μm microparticles and separation efficiency for 5 μm particles can reach up to 98.28% and 93.85% respectively. For bacteria and microalgae cells separation, the removal ratio for bacteria and separation efficiency for microalgae cells is 92.69% and 100% respectively. This work demonstrated the continuous and sheathless separation of microalgae from bacteria for the first time by viscoelastic microfluidics. This technique can also be applied as an efficient and user-friendly method to separate mammalian cells or other kinds of cells.

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Contributors

Author: Shi Yang Tang

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