Particle migration in viscoelastic microfluidics

I ABSTRACT Particle migration is very important and essential for focusing, separating, counting, detecting or analysis in numerous biological and chemical applications. A variety of microfluidic devices have been designed to realize particle migration in Newtonian fluids. With the aid of external force fields, specially designed channel structures, or hydrodynamic forces, particles can migrate to one or several equilibrium positions in Newtonian fluids. While extensive research on fundamentals and application based on particle migration in Newtonian fluids has been conducted, there are fewer research on particle migration in non-Newtonian fluids. Actually, non-Newtonian fluids such as blood, cytoplasm, and many other body fluids, are very ubiquitous in our daily life and in real world issues. Therefore, it is important to invest our research focus on particle migration in non-Newtonian fluids to develop deep understanding of cell behaviours in these body fluids. Recently, the research interests on particle migration based on non-Newtonian fluid have been increasing. The increasing attention on particle migration based on non-Newtonian fluids is a result of its interesting intrinsic fluid properties. Compared with particle focusing in a Newtonian fluid, 3D particle focusing in a non-Newtonian fluid can be easily realized in simple channels without the need of any external force fields; and particles with a much smaller size, such as from submicrometer to even nanometer particles can be manipulated. Particle migration in non-Newtonian fluids can break the limitations of requiring extra external components, lower throughput, complex fabrications in Newtonian fluids. Moreover, it can develop simpler, more flexible and versatile particle manipulation methods with lower costs. These advantages of non-Newtonian fluids allow fast growth of microfluidic applications based on viscoelastisity-induced particle migration, enabling the development of various micro-devices for bi