Good defects, or what frustrated liquid crystals can do

Abstract:

Liquid crystals are best known for their use in displays, but their interest extends far beyond. This phase of matter, intermediate between liquid and solid, is composed by anisotropic molecules which spontaneously align in space. When the molecules cannot achieve a perfect order, they form topological defects, “mathematical” objects which can be used as physical objects for many purposes. I show two examples of how liquid crystal defects can inspire concepts for new materials. The first example is a bistable system, obtained by confining liquid crystals in a micron-sized cubic scaffold.  The device can switch between “bright” and “dark” metastable states, thanks to the interaction of the defects with the scaffold. The second example is a self-assembled  structure of liquid crystal defects that act as micro-lenses. The structure resembles an insect’s compound eye, able to focus objects at different distances and sensitive to the polarization of light.