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Updated: Aug 5, 2026

Tangential Flow Ultrafiltration: A “Green” Method for the Size Selection and Concentration of Colloidal Silver Nanoparticles
Published on: October 4, 2012
An electric bottle for colloids
M T Sullivan1, K Zhao, A D Hollingsworth
1Department of Physics, Princeton University, Princeton, New Jersey 08544, USA.
Abstract:
Particle concentration is a dominant control parameter for colloids and other soft matter systems. We demonstrate a simple technique, "dielectrophoretic equilibrium," implemented as an "electric bottle," a planar capacitor in a larger volume. The uniform field in the capacitor traps particles in this force-free region at a higher density than in the zero field regions outside. We show how the technique measures the equation of state and we initiate and grow colloidal crystals. "Dielectrophoretic equilibria" enable the study of a complete concentration-dependent phase diagram from a single microscopic sample, obviating the previous need for preparing a large number of samples.
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