Nonspherical double emulsions with multiple distinct cores enveloped by ultrathin shells

Area of Science:

• Microfluidics
• Materials Science
• Chemical Engineering

Background:

• Microfluidics enables precise control over emulsification for producing monodisperse double-emulsion drops.
• These drops are valuable templates for creating microcapsules with specific functionalities.

Purpose of the Study:

• To introduce a novel capillary microfluidic device design for generating nonspherical double-emulsion drops.
• To create templates with multiple distinct cores and ultrathin middle layers for advanced microcapsule fabrication.

Main Methods:

• Parallelization of capillary channels, each featuring a core-sheath biphasic flow.
• Achieving core-sheath flow via preferential wetting of oil to hydrophobic channel walls.
• Concurrent emulsification of core-sheath streams into a continuous phase to form paired double-emulsion drops.

Main Results:

• Successful fabrication of nonspherical double-emulsion drops with multiple cores and thin middle shells.
• Demonstration of high controllability over drop size, shape, number, and composition.
• Observation of strong capillary forces in nonspherical envelopes promoting inner drop coalescence.

Conclusions:

• The developed microfluidic approach offers flexibility for creating complex double-emulsion templates.
• These templates are suitable for producing multicompartment microcapsules capable of co-delivering distinct components without cross-contamination.
• Potential applications include nanoliter-scale reactions and controlled encapsulation of reaction products.