APPLIED PHYSICS: Tilting at Towers

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Science  31 May 2002:
Vol. 296, Issue 5573, pp. 1571c
DOI: 10.1126/science.296.5573.1571c

Within a localized volume, the anisotropic molecules of a nematic liquid crystal will tend to orient in one general direction, called the director. For electro-optical devices, the orientation of the director is established by rubbing the substrate, which creates microscopic aligned grooves that interact with the liquid crystal molecules. Macroscopic features, such as short posts attached to the substrate, can also create localized variations in director alignment; several stable orientations may exist, but it can be difficult to switch between them.

Kitson and Geisow use tall posts or towers that induce a tilting of the director relative to the substrate. A lattice of these posts produces a small tilt in one direction, creating a device that has two stable states, differing only in director orientation. By applying a voltage pulse, they can switch between the bistable states, rendering the features either light or dark. Unlike other liquid crystal devices, the pattern remains stable after the current is shut off. — MSL

Appl. Phys. Lett. 80, 3635 (2002).

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