(432c) Effect of Particle Softness in Microfluidic Clogging Dynamics

In transport of suspensions in microchannels, clogging occurs when particles prevent further flow of suspensions downstream. Understanding the dynamics of clog formation is important in several applications involving the flow of particulate suspensions: a common application of clogging is in its use as a measure of the deformability of red blood cells ¹. Clogging has been observed both in dense and dilute suspensions of rigid spheres, and can occur when the particles size is much smaller than the narrowest dimension of a microchannel ². The formation of clogs can be initiated when the minimum number of particles sufficient to form an arch across the constriction width arrives at the same instant and jam. While this phenomenon is well studied for suspensions of rigid microbeads, the mechanism is less well understood for soft elastic microbeads and non-spherical particles ³.

In this study, we explore the effect of particle rigidity on clogging dynamics by comparing suspension flows of silica microbeads to deformable polymeric particles in a custom microfluidic device. The influence of particle size, concentration and driving pressure are also examined. Preliminary results suggest both a fast and slow process in the clogging dynamics. We explore the dependence of each step in the process on particle size, rigidity and driving pressure, and hypothesize that fast dynamics arise from the formation of bridging arches across the constriction at the initial clogging site, which is followed by the slower growth of the filter cake.

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