Biaxial nanowrinkling in cholesteric surfaces: Egg carton surfaces through chiral anchoring

Periodic micro and nano-structured surfaces in nature are responsible for functionalities including structural colour, superhydrophobicity, where wrinkling plays a significant role. The Bouligand architecture of fibrous composites such as insect exoskeleton plant cell walls has been shown to generate uniaxial single multiscale nanowrinkling through the chiral capillarity effect due anisotropic surface tension helical fibre arrangement. arrangement structures is solid analogue cholesteric liquid crystal, which an intermediate stage self-assembly formation process composites. We extend predictions biaxial show, using crystal shape equation, how why egg carton with orthogonal patterning arise, since planar helix tangential unstable oblique modes. Taken together this work contributes novel pattern engineering principles study biological materials.