Microfluidic ultralow interfacial tensiometry with magnetic particles

We describe a technique that measures ultralow interfacial tensions using paramagnetic spheres in a co-flow microfluidic device designed with a magnetic section. Our method involves tuning the distance between the co-flowing interface and the magnet's center, and observing the behavior of the s...

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Bibliographic Details
Published in:Lab on a chip 2013-01, Vol.13 (1), p.119-125
Main Authors: Tsai, Scott S H, Wexler, Jason S, Wan, Jiandi, Stone, Howard A
Format: Article
Language:English
Subjects:
Devices
Estimates
Impact tests
Interfacial tension
Microfluidics
Surfactants
Thresholds
Tuning
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Summary:We describe a technique that measures ultralow interfacial tensions using paramagnetic spheres in a co-flow microfluidic device designed with a magnetic section. Our method involves tuning the distance between the co-flowing interface and the magnet's center, and observing the behavior of the spheres as they approach the liquid-liquid interface-the particles either pass through or are trapped by the interface. Using threshold values of the magnet-to-interface distance, we make estimates of the two-fluid interfacial tension. We demonstrate the effectiveness of this technique for measuring very low interfacial tensions, O(10(-6)-10(-5)) N m(-1), by testing solutions of different surfactant concentrations, and we show that our results are comparable with measurements made using a spinning drop tensiometer.
ISSN:1473-0197
1473-0189
DOI:10.1039/c2lc40797c