Adhesion Reduction at Solid/Liquid Interfaces Based on Topologically Optimized Microtextures

Artificial microtextures adopted to achieve adhesion reduction help avoid the vulnerability associated with chemical coatings. Most current microtextures strongly rely on biological inspiration or designers' physical intuition. There are also manufacturing challenges due to the complex geometrical configurations. Topology optimization can determine the structural configurations encompassing geometric information on topology, shape, and size and ensure the manufacturability of the optimized microtextures by controlling the feature size corresponding to a specified fabrication process. Herein, we present an approach to reduce the liquid adhesion on solid surfaces by employing artificial microtextures with hexagonal periodicity, where the microtextures are inversely designed through topology optimization. The microtextures are fabricated of polydimethylsiloxane by using a soft lithography process. The liquid adhesion on the microtextures is measured via the tilting plate method. Experimental results demonstrate that the topologically optimized microtextures can significantly reduce the liquid adhesion by 45.0%, which is achieved by the robust Cassie-Baxter state of the wetting behavior. The topologically optimized microtextures can also support the robust Cassie-Baxter state underwater and accelerate the speed when the droplets slide off the surface with them. The findings can be utilized in the context of the reduction of underwater drag and bioadhesion.