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Updated: Aug 31, 2025
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Fabricating High-viscosity Droplets using Microfluidic Capillary Device with Phase-inversion Co-flow Structure
Published on: April 17, 2018
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Phase separation in evaporating all-aqueous sessile drops.
Alexander May1, Johannes Hartmann1, Steffen Hardt1
1Technische Universität Darmstadt, Fachbereich Maschinenbau, Fachgebiet Nano-und Mikrofluidik, Alarich-Weiss-Str. 10, 64287 Darmstadt, Germany. hardt@nmf.tu-darmstadt.de.
Soft Matter
|August 22, 2022
Summary
Water evaporation in a polyethylene glycol (PEG) and dextran solution causes phase separation. Dextran-rich droplets form and move to the center due to Marangoni convection.
Area of Science:
- Fluid dynamics
- Materials science
- Physical chemistry
Background:
- Phase transitions in polymer solutions are crucial for understanding material properties.
- Sessile drops offer a unique microfluidic environment for studying dynamic processes.
- Polyethylene glycol (PEG) and dextran are widely used biopolymers with distinct properties.
Purpose of the Study:
- To investigate the phase behavior and droplet dynamics in an all-aqueous PEG-dextran system.
- To understand the mechanisms driving droplet formation and migration during evaporation.
- To explore the role of interfacial stresses in fluid motion within the sessile drop.
Main Methods:
- Utilizing an all-aqueous sessile drop setup.
- Inducing phase separation through controlled water evaporation.
- Observing droplet formation and migration using microscopy.
- Analyzing fluid flow patterns, potentially through particle tracking or interferometry.
Main Results:
- Evaporation of water leads to the formation of dextran-rich droplets near the contact line.
- These dextran-rich droplets exhibit directed migration towards the center of the sessile drop.
- The observed migration is attributed to Marangoni convection, driven by interfacial tension gradients.
Conclusions:
- Water evaporation is a key trigger for phase separation and dynamic droplet behavior in PEG-dextran solutions.
- Marangoni convection plays a significant role in the observed droplet migration, highlighting the importance of interfacial phenomena.
- This study provides insights into the complex interplay of phase transitions and fluid dynamics in confined aqueous polymer systems.
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