Drying mediated pattern formation in a capillary-held organometallic polymer solution

A simple route to produce highly circular concentric ring patterns in an easily controllable, cost-effective, and reproducible manner simply by allowing a drop to evaporate in a confined geometry consisting of a sphere on a Si surface was investigated. The confined geometry facilitates the suppression of hydrodynamic instabilities and convection due to the facts that the experiments were performed inside a chamber and evaporation was constrained to occur at the capillary edge. The confined geometry provided a unique environment for controlling the flow within the evaporating droplet. The results show that the concentric ring patterns could be used as etching barriers for preparing features with high aspect ratio.