Premium
Concentrating particles on drop surfaces using external electric fields
Author(s) -
Nudurupati Sai,
Janjua Mohammad,
Aubry Nadine,
Singh Pushpendra
Publication year - 2008
Publication title -
electrophoresis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.666
H-Index - 158
eISSN - 1522-2683
pISSN - 0173-0835
DOI - 10.1002/elps.200700676
Subject(s) - drop (telecommunication) , electric field , spinning drop method , liquid drop , mechanics , equator , materials science , voltage drop , dielectric , condensed matter physics , optics , physics , current (fluid) , thermodynamics , pressure drop , optoelectronics , electrical engineering , quantum mechanics , astronomy , latitude , engineering
Abstract We propose to use an externally applied uniform electric field to alter the distribution of particles on the surface of a drop immersed in another immiscible liquid. Specifically, we seek to generate well‐defined concentrated regions at the drop surface while leaving the rest of the surface particle free. Experiments show that when the dielectric constant of the drop is greater than that of the ambient liquid the particles for which the Clausius–Mossotti factor is positive move along the drop surface to the two poles of the drop. Particles with a negative Clausius–Mossotti factor, on the other hand, move along the drop surface to form a ring near the drop equator. The opposite takes place when the dielectric constant of the drop is smaller than that of the ambient liquid, namely particles for which the Clausius–Mossotti factor is positive form a ring near the equator while those for which such a factor is negative move to the poles. This motion is due to the dielectrophoretic force that acts upon particles because the electric field on the surface of the drop is nonuniform, despite the uniformity of the applied electric field. Experiments also show that when small particles collect at the poles of a deformed drop the electric field needed to break the drop is smaller than without particles. These phenomena could be useful to concentrate particles at a drop surface within well‐defined regions (poles and equator), separate two types of particles at the surface of a drop or increase the drop deformation to accelerate drop breakup.