Complex patterning of matter with liesegang patterns propagating through different concentration media─gel lenses for liesegang waves

Abstract

The patterns formed in natural biochemical and geochemical media are never spatially or geometrically homogeneous. On the other hand, the artificial systems trying to mimic nature are usually homogeneous and far from depicting the complexity of the natural ones. Liesegang patterns (LPs) are artificial reaction-diffusion precipitate patterns that can be formed in hydrogels. Although these patterns can be made to “sense” the environment, they are mostly formed in homogeneous media. Here, we present that a simple setting of different gel concentration boundaries can cause refractions of the pattern waves and changes in the band spacings. The extent of refraction is dependent on the macroscopic shape of the boundary. As imaged by scanning electron microscopy, the LP bands “crossing the boundaries” are formed by the product of a new morphology. This study can be a step forward in straightforwardly achieving complexity in artificial systems and developing new crystal forms of solids.