Deformation of an elastic capsule in a rectangular microfluidic channel

Area of Science:

• Computational fluid dynamics
• Microfluidics
• Biophysics

Background:

• Capsule deformation in microfluidic channels is crucial for understanding cell dynamics in biological systems.
• Previous studies focused on capsule and droplet behavior in square or cylindrical channels, showing elongation along the flow direction.
• The distinct mechanical properties of capsules, droplets, and vesicles influence their deformation under flow.

Purpose of the Study:

• To computationally investigate the deformation of elastic capsules in a rectangular microfluidic channel.
• To compare capsule deformation in rectangular channels with that of droplets and vesicles in various channel geometries.
• To elucidate the factors governing interfacial stability and shape evolution in different confinement scenarios.

Main Methods:

• Numerical simulations of elastic capsule deformation within a rectangular microfluidic channel.
• Comparative analysis of capsule, droplet, and vesicle behavior under asymmetric channel flow conditions.
• Investigation of membrane tension development and its role in interfacial stability.

Main Results:

• In rectangular channels, capsules adopt a pebble-like shape, extending laterally due to lower confinement, contrasting with bullet/parachute shapes in other geometries.
• Capsule deformation differs significantly from droplets (extending along flow) and vesicles (extending along channel height) in asymmetric flows.
• The observed differences in shape evolution are attributed to varying tension development on the interface for stability.

Conclusions:

• Capsule deformation dynamics are highly sensitive to channel geometry and confinement.
• The study highlights distinct stability dynamics among capsules, droplets, and vesicles in microfluidic flows.
• Erythrocyte deformation in asymmetric vessels may be governed by its internal spectrin skeleton, similar to capsule behavior.