Anisotropic wetting on structured surfaces

Directional textured surfaces help butterflies to shed water from their wings, pitcher plants to capture prey, and water striders and certain beetles and spiders to walk on water. Inspired by natural directional surfaces, researchers have developed a myriad of synthetic surfaces with precisely tuned physicochemical properties to regulate wettable adhesion. Anisotropic surfaces are of great value to the energy and biomedical fields for applications such as directional syringes, microprocessor cooling, high-efficiency hydropower turbines, and nanoscale digital fluidics. We summarize experimental and theoretical approaches to the design, synthesis, and characterization of engineered surfaces demonstrating anisotropic wetting properties.