(606c) The Response of Anisotropic Colloidal Particles to a Nearby Electrode

Recent work has shown that colloidal crystals with intricate and complex microstructure can be fabricated from anisotropic particles responding to an electric field. Anisotropic particles, such as doublets with lobes of dissimilar zeta potential, will tend to form assemblies with more complex microstructure than those fabricated from isotropic particles because anisotropic particles will interact via directionally dependent forces. This presentation will summarize recent work in our group focused on the response of non-spherical particles to a nearby electrode. The force, torque, and resulting motion of homo- and heterogeneous doublets was calculated in response to a DC electric field. A non-zero force on the doublet in the direction perpendicular to the applied electric field was obtained as a consequence of the unbalanced equilibrium charge electroosmotic (ECEO) flow generated along the particleâ??s surface; the strength of the flow field depended on the sign and magnitude of the lobe zeta potential and weakly on the shape of the particle. Moreover, the ECEO flow field and the accompanying interparticle interactions were anisotropic. Experiments measuring the response of doublets and ellipsoids to DC and AC electric fields will also be presented. These results suggest a strategy by which one can design 2D interparticle interactions to achieve a specific ensemble microstructure.