Mechanical Characterization of Ultralow Interfacial Tension Oil-in-Water Droplets by Thermal Capillary Wave Analysis in a Microfluidic Device

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• 作者：Guido Bolognesi ; Yuki Saito ; Arwen I. I. Tyler ; Andrew D. Ward ; Colin D. Bain ; Oscar Ces
• 刊名：Langmuir
• 出版年：2016
• 出版时间：April 19, 2016
• 年：2016
• 卷：32
• 期：15
• 页码：3580-3586
• 全文大小：360K
• 年卷期：0
• ISSN：1520-5827

文摘

Measurements of the ultralow interfacial tension and surfactant film bending rigidity for micron-sized heptane droplets in bis(2-ethylhexyl) sodium sulfosuccinate–NaCl aqueous solutions were performed in a microfluidic device through the analysis of thermally driven droplet interface fluctuations. The Fourier spectrum of the stochastic droplet interface displacement was measured through bright-field video microscopy and a contour analysis technique. The droplet interfacial tension, together with the surfactant film bending rigidity, was obtained by fitting the experimental results to the prediction of a capillary wave model. Compared to existing methods for ultralow interfacial tension measurements, this contactless, nondestructive, all-optical approach has several advantages, such as fast measurement, easy implementation, cost-effectiveness, reduced amount of liquids, and integration into lab-on-a-chip devices.