6 research outputs found
Nonlinear electrophoresis of dielectric and metal spheres in a nematic liquid crystal
Electrophoresis is a motion of charged dispersed particles relative to a
fluid in a uniform electric field. The effect is widely used to separate
macromolecules, to assemble colloidal structures, to transport particles in
nano- and micro-fluidic devices and displays. Typically, the fluid is isotropic
(for example, water) and the electrophoretic velocity is linearly proportional
to the electric field. In linear electrophoresis, only a direct current (DC)
field can drive the particles. An alternate current (AC) field is more
desirable because it allows one to overcome problems such as electrolysis and
absence of steady flows. Here we show that when the electrophoresis is
performed in a nematic fluid, the effect becomes strongly non-linear with a
velocity component that is quadratic in the applied voltage and has a direction
that generally differs from the direction of linear velocity. The new
phenomenon is caused by distortions of the LC orientation around the particle
that break the fore-aft (or left-right) symmetry. The effect allows one to
transport both charged and neutral particles, even when the particles
themselves are perfectly symmetric (spherical), thus enabling new approaches in
display technologies, colloidal assembly, separation, microfluidic and
micromotor applications.Comment: 15 pages, 4 figure