Squeezing multiple soft particles into a constriction: transition to clogging

Flows of particles are largely encountered in microfluidic devices designed to manipulate micro-sized artificial particles or living cells. As the particle size is generally the same order as the channel width, the performance of such devices could dramatically be hindered by clogging events. While there is an increasing need to improve the capability of microfluidic devices to handle high throughput, this study is carried out to address the scenarios that emerge when multiple soft particles flow through a microfluidic constriction.

The flow of soft particles in a microfluidic constriction involves strong fluid-structure interactions and is numerically solved using a combination of the lattice Boltzmann method, the finite element method and the immersed boundaries method. Two main characteristic scenarios are obtained: the particles form a permanent clog at the constriction entrance, or they pass freely through the constriction. The transition to clogging is found to be mainly controlled by the ratio of the particle size to the constriction width and the particles deformability. The results are reported in a state diagram, which indicates whether or not the particles clog the channel, depending on the constriction-to-particle size ratio and the deformability of the particles.