Oral: Pattern Formation in a Solid-State System Driven by the Euler Instability

We present a solid state system which spontaneously forms incredible patterns on a Germanium surface. Regular structures at the 10 – 100 µm scale, such as spirals, are spontaneously repeated hundreds of times on a chip. The patterns are created by chemical etching in the presence of a thin film metal catalyst. They arise spontaneously from homogeneous initial conditions. The growth mechanism is unusual, in that it involves coupling of a chemical reaction to the mechanical instabilities of the catalyst metal layer. The result has similarities with Turing patterns, crack propagation, and biological form.