Particle segregation using crystal-like structure of capsules in wall-bounded shear flow

Abstract

In a wall-bounded shear flow, deformable particles form a crystal-like structure. To examine particle sorting in microfluidic devices we added small capsules (SC) to a system where large capsules (LC) form a crystal structure, and find that the movement of SC changes significantly with size ratio ${R}_{a}$. When SC and LC are of comparable size (${R}_{a}\ensuremath{\sim}1$), the small capsules are trapped in the crystal structure, whereas when SC are smaller (${R}_{a}\ensuremath{\sim}0.6$ or lower) the SC deplete from the crystal layer due to low lift velocity. This suggests that the crystal structure of capsules can be used to trap capsules of comparable sizes, or to exclude capsules of smaller sizes.