Characterizing the membrane properties of capsules flowing in a square-section microfluidic channel: Effects of the membrane constitutive law

摘要

Amicrofluidic method is presented tomeasure the elastic membrane properties of a population ofmicrocapsuleswith diameter of order 60 μm. The technique consists of flowing a suspension of capsules enclosed bya polymerized ovalbumin membrane through a square-section microfluidic channel with cross dimensioncomparable with the capsule mean diameter. The deformed profile and the velocity of a given capsule arerecorded. A full mechanical model of the motion and deformation of an initially spherical capsule flowing insidea square-section channel is designed for different flow strengths, confinement ratios, and membrane constitutivelaws. The experimental deformed profiles are analyzed with the numerical model. This allows us to find the ratiobetween the viscous and elastic forces and thus the shear elastic modulus of the membrane. We show that theovalbumin membrane tends to have a strain-softening behavior under the conditions studied here.