Geometric binding site design for surface-tension driven self-assembly

Surface-tension driven self-assembly techniques have been successfully employed to assemble and align micro parts on hydrophobic binding sites on a substrate. The driving force for assembly is provided by a liquid lubricant meniscus confined between two hydrophobic surfaces in an aqueous environment. Therefore, the hydrophobic pattern design becomes a critical issue for the self-assembly process. With an ideal design, the part can assemble in a unique position and orientation. In this paper, we study a series of geometric designs based on a first-order approximation energy model. An optimization method is developed to evaluate them, and a class of optimal designs is found consisting of asymmetric rings with additional geometric constraints.