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 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.

[1]  Michiel T. Kreutzer,et al.  All-aqueous core-shell droplets produced in a microfluidic device , 2011 .

[2]  H. Stone,et al.  Conformal coating of particles in microchannels by magnetic forcing , 2011 .

[3]  Howard A Stone,et al.  Microfluidic immunomagnetic multi-target sorting--a model for controlling deflection of paramagnetic beads. , 2011, Lab on a chip.

[4]  Howard A. Stone,et al.  Corrugated interfaces in multiphase core-annular flow , 2010, 1204.4977.

[5]  Jianhong Xu,et al.  A new interfacial tension measurement method through a pore array micro-structured device. , 2009, Journal of colloid and interface science.

[6]  G. Luo,et al.  Microfluidic approach for rapid interfacial tension measurement. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[7]  K. Nichols,et al.  Electrowetting-based microdrop tensiometer. , 2008, Langmuir : the ACS journal of surfaces and colloids.

[8]  D. Bonn,et al.  Life at ultralow interfacial tension: wetting, waves and droplets in demixed colloid-polymer mixtures , 2008 .

[9]  Ashok Sinha,et al.  Single magnetic particle dynamics in a microchannel , 2007 .

[10]  Andrés L. Márquez,et al.  Water in oil (w/o) and double (w/o/w) emulsions prepared with spans: microstructure, stability, and rheology , 2007 .

[11]  Christopher D. Mellor,et al.  Optical sculpture: controlled deformation of emulsion droplets with ultralow interfacial tensions using optical tweezers. , 2006, Chemical communications.

[12]  S. D. Hudson,et al.  Microfluidic approach for rapid multicomponent interfacial tensiometry. , 2006, Lab on a chip.

[13]  H. Bruus,et al.  Microfluidic capturing-dynamics of paramagnetic bead suspensions. , 2005, Lab on a chip.

[14]  G. Fonnum,et al.  Characterisation of Dynabeads® by magnetization measurements and Mössbauer spectroscopy , 2005 .

[15]  M. J. Rosen,et al.  Ultralow interfacial tension for enhanced oil recovery at very low surfactant concentrations. , 2005, Langmuir : the ACS journal of surfaces and colloids.

[16]  H. Lekkerkerker,et al.  Interfacial dynamics in demixing systems with ultralow interfacial tension , 2005 .

[17]  Andreas Manz,et al.  On-chip free-flow magnetophoresis: continuous flow separation of magnetic particles and agglomerates. , 2004, Analytical chemistry.

[18]  Dirk G. A. L. Aarts,et al.  Direct Visual Observation of Thermal Capillary Waves , 2004, Science.

[19]  K. Sakai,et al.  Measurement of ultralow interfacial tension with a laser interface manipulation technique. , 2002, Physical review. E, Statistical, nonlinear, and soft matter physics.

[20]  G M Whitesides,et al.  Fabrication of topologically complex three-dimensional microfluidic systems in PDMS by rapid prototyping. , 2000, Analytical chemistry.

[21]  H. Lekkerkerker,et al.  Measurement of the interfacial tension of a phase-separated colloid-polymer suspension , 1999 .

[22]  K. Shinoda,et al.  Solution behavior and hydrophile-lipophile balance temperature in the aerosol OT-isooctane-brine system: Correlation between microemulsions and ultralow interfacial tensions , 1980 .

[23]  J. J. Taber,et al.  Dynamic and static forces required to remove a discontinuous oil phase from porous media containing both oil and water , 1969 .

[24]  E. Bart.  The slow unsteady settling of a fluid sphere toward a flat fluid interface , 1968 .

[25]  H. Brenner.  The slow motion of a sphere through a viscous fluid towards a plane surface , 1961 .