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Mirofluidic Appproach for Rapid Interfacial Tensiometry



J Cabral, Steven Hudson


We report a microfluidic instrument to rapidly measure the interfacial tension of multi-component immiscible liquids. The measurement principle rests upon the deformation and retraction dynamics of drops under extensional flow and was implemented in microfluidics (Hudson et al., Appl. Phys. Lett (2005) [1]). We now describe in detail the instrument design and implementation and demonstrate, for the first time, measurements on binary drops mixtures. The microfluidic circuit produces drops of controlled size and spacing, which are accelerated and subjected to extensional flow gradients imposed by flow constrictions. Drop deformation is monitored using optical microscopy. Image analysis of drop shape, position and velocity, combined with a classical Taylor model yield the liquids' interfacial tension (ift) in real time.The experimental setup consists of an inverted optical microscope, a relatively fast CCD camera (50 fps) and a series of syringe pumps, and is computer controlled with a LabVIEW interface. The device is fabricated using rapid prototyping techniques. This approach provides fast ift measurements (in the order of 1 second), the possibility of rapidly adjusting drop composition and utilizes small sample volumes (order of 10 microliter). The tensiometer operation is illustrated with water drops and binary drops (water/ethylene glycol mixtures) in silicone oils. The technique should be particularly valuable for high-throughput characterization of complex fluids.
Lab on A Chip


high-throughput, instrument development, interfacial tension, microfludics, mixtures


Cabral, J. and Hudson, S. (2006), Mirofluidic Appproach for Rapid Interfacial Tensiometry, Lab on A Chip, [online], (Accessed July 25, 2024)


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Created January 31, 2006, Updated October 12, 2021