Field-Induced Layering of Colloidal Crystals
M. Trau,
D. A. Saville,
I. A. Aksay
*
An electrohydrodynamic methodology has been developed that makes
possible the precise assembly of two- and three-dimensional colloidal
crystals on electrode surfaces. Electrophoretically deposited colloidal
particles were observed to move toward one another over very large
distances (greater than five particle diameters) to form
two-dimensional colloidal crystals for both micrometer- and
nanometer-size particles. This coalescence of particles with the same
charge is opposite to what is expected from electrostatic
considerations and appears to result from electrohydrodynamic fluid
flow arising from an ionic current flowing through the solution. The
ability to modulate this ``lateral attraction'' between particles,
by adjusting field strength or frequency, facilitates the reversible
formation of two-dimensional fluid and crystalline colloidal states on
the electrode surface. Further manipulation allows controlled
structures to be assembled.
Department of Chemical Engineering and Princeton Materials
Institute, Princeton University, Princeton, NJ 08544, USA.
*
To whom correspondence should be addressed.
