Effects of fluid rheology on particle-focusing behavior in a spiral microchannel

Passive particle manipulation in non-Newtonian fluids through microchannels has received scientific attention due to its biomedical and chemical applications requiring size–based focusing and separation of microparticles. In Non-Newtonian fluids through curved microchannels, particle-focusing is achieved due to the synergy between inertial lift, elastic lift, and dean drag force. In addition, the complex rheological properties exhibited by non-Newtonian fluids highly influence the focusing behavior. We investigate in this work the effects of fluid rheology on particle-focusing behavior in a spiral microchannel by employing polymer solutions with varying rheological properties. Focusing behavior is examined over a range of Reynolds and Weissenberg numbers at the outlet region of the microchannel. A systematic experimental approach aids in decomposing the fluid rheology effects on particle migration and focusing. This work explores the individual and combined effects of inertia, elasticity, and shear thinning property on particle-focusing behavior.