Directional fluidization of concentrated emulsion induced by asymmetric wall roughness

Controlling the flow of soft glassy materials (SGMs) at the microscale is essential for many applications, ranging from pharmaceuticals to food technology. SGM include dense emulsions, foams, and gels. These materials have a peculiar non-Newtonian rheology described by the Herschel-Bulkley model; they behave like a solid unless a threshold stress is applied. Above this stress, they flow as a liquid. Previous studies have shown that this transition can be induced by the presence of a microroughness patterned on the walls of a microfluidic channel. This roughness activates local plastic rearrangements, causing a reduction in local viscosity and, consequently, fluidization of the material. The way these rearrangements are influenced by microtexturing remains an open question and is currently the subject of theoretical and experimental investigation. The student will realize microfluidic channels patterned with different asymmetric geometries and characterize their efficiency with respect to the fluidization transition of the concentrated emulsions.