Encapsulated Cell Dynamics in Droplet Microfluidic Devices with Sheath Flow.

Area of Science:

• Biophysics
• Microfluidics
• Cellular Dynamics

Background:

• Microfluidic devices enable precise control over cellular environments.
• Encapsulating single cells in droplets creates micro-reactors for studying cellular behavior.
• Cellular biomechanical properties are crucial for understanding cell function and disease.

Purpose of the Study:

• To investigate the rotational dynamics of single cells within microfluidic droplets.
• To explore the impact of enhanced flow fields on cell behavior and biomechanical property extraction.
• To develop label-free methods for rare cell detection using cellular dynamics.

Main Methods:

• Utilizing microfluidic channels with water-in-oil emulsions to encapsulate single cells.
• Coupling microchannel flow fields with internal droplet flow fields via viscous traction.
• Employing high-speed cameras for monitoring cell dynamics (orbits, spins, deformations).
• Developing a numerical multi-phase flow model to analyze rotational flow fields and fluid-fluid interfaces.
• Implementing a sheath flow microchannel to strengthen internal droplet flow.

Main Results:

• A rotational flow field is induced inside droplets, causing encapsulated cells to orbit, spin, and deform.
• Sheath flow significantly enhances the rotational flow field within droplets.
• Cell orbiting speed was experimentally doubled by implementing sheath flow.
• Numerical models confirmed the influence of various parameters on internal droplet flow.
• Increased cell speed allows for doubled biomechanical information extraction within camera's field of view.

Conclusions:

• Microfluidic droplet dynamics can be manipulated to study cellular biomechanics.
• Sheath flow is an effective strategy to enhance cell dynamics for improved analysis.
• This approach offers a promising label-free method for detecting rare cells based on their physical properties.