Reconfigurable swarms of nematic colloids controlled by photoactivated surface patterns
| When |
Feb 10, 2015
from 10:45 to 12:00 |
|---|---|
| Where | Salle des Commissions |
| Attendees |
Jordi Ignes-Mullol |
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Different phoretic driving mechanisms have been proposed for the transport of solid or liquid microscopic inclusions in integrated processes. In this talk, I will present recent experiments where colloidal microparticles dispersed in a nematic liquid crystal cell are driven into self-assembly by means of non-linear induced charge electrophoresis [1,2] using an AC field perpendicular to the plates. We take advantage of the configuration of the liquid crystal cell to design reconfigurable trajectories using a photosensitive anchoring layer (azosilane self-assembled monolayer), as the particle trajectory follows the local director orientation. Assembled particle flocks travel as swarms following paths that can be reconfigured in real time by a combination of UV and visible light. By separating particle steering and driving, these experiments present a simple and robust strategy for large scale addressability of ensembles of steered colloids, with full spatial and immediate temporal control, relying solely on generic properties of the host nematic and of the dispersed materials.
[1] Lavrentovich, O. D. et al., Nature 467, 947 (2010).
[2] Lavrentovich, O. D., Soft Matter 10, 1264 (2014).