Dynamics of a rodlike deformable particle passing through a constriction

Abstract

We use the finite element method to investigate the flow-induced translocation of a rodlike deformable particle through a narrow constriction in a microchannel from a dynamical perspective. Our results demonstrate that the deformable particle exhibits two translocation modes, one with folded deformation and one with unfolded deformation, depending mainly on the initial deflection angle. When the initial deflection angle is small, the deformable particle undergoes folded deformation, which changes to unfolded deformation as the angle increases. Depending on its initial location with respect to the axis of the microchannel, the deformable particle exhibits swinging motion or one of two types of tumbling motion: tumbling I (90° < θ < 180°, where θ is the rotation angle) and tumbling II (θ > 180°). Swinging motion occurs when the initial position is close to the axis, and this is converted to tumbling I and tumbling II motions when the initial position moves away from the axis. Our results provide a description of the deformation and motion of a rodlike deformable particle during its passage through a constriction, which can be useful for understanding the role of deformable particles in physiological processes, for cell separation, and for the application of deformable particles in drug delivery.