(142e) Determination of the Elastic Properties of Artificial Micro-Capsules in Microfluidic Devices

The study of the interfacial dynamics of artificial or physiological
capsules (i.e. membrane-enclosed fluid volumes) in viscous flows has
seen an increased interest during the last few decades due to their
numerous engineering and biomedical applications.  The determination of
the elastic properties of the membrane of artificial capsules, i.e. the
shear and area-dilatation moduli, is essential for the better design of
the various devices they are utilized.  For this, several techniques have
been developed including static compression and shear, extensional or
centrifugal flow fields for milli-capsules as well as micropipette and
atomic force microscope measurements, and flow in microfluidic channels
and tubes for micro-capsules.  We emphasize that a membrane mechanical
determination is a challenging task, where two experimental techniques
are commonly required to account for the combined effects of the shear
and area-dilatation moduli on the membrane deformation.

In this talk we will discuss a new methodology to identify a capsule
mechanical properties utilizing a single experimental technique, by
comparing our computation data with experimental measurements of the
capsule dimensions at moderate and strong planar extensional flows in
classical or microfluidic four-roll mill devices.

In addition, we will propose a new methodology to determine a membrane's
shear modulus, independently of its area-dilatation modulus, by
flowing of capsules in a specific micro-fluidic geometry and comparing
experimental measurements with our computational data.  Our proposed
experimental device can be combined with a microfluidic device for
capsules fabrication so that it is possible in situ fabrication and
characterization of a large number of artificial capsules.