Durable, flexible, superhydrophobic and blood-repelling surfaces for use in medical blood pumps

Extracorporeal blood pumps expose blood to high stresses and can cause blood damage or clotting, leading to serious complications and death. One possible solution is to use superhydrophobic (SHP) surfaces to reduce blood stresses via slip flow. However, current SHP surfaces have the durability problem, or are difficult to customize into complex 3D shapes. Here, we report a novel sand-casting technique to prepare a SHP and blood-repelling surface made of silicone and functionalized SiO₂ nanoparticles, which is durable, flexible, and customizable into complex 3D shapes with relative ease. Compared to plain silicone surfaces, the casted surface can reduce the water drag force by up to 72%. The casted item is mechanically durable, maintaining its SHP properties after repeated tape peeling and alcohol swab rubbing, high-speed (9.7 m s^-1) water impacting, and high-pressure sandpaper abrasion. Its flexibility is also demonstrated by retention of its superhydrophobicity after repeated bending. Moreover, the material is SHP as prepared. This allows the material to be shape-customizable, simply by preparing molds of specific 3D geometries for sand-casting, which will be useful on surfaces of complex 3D shapes. This SHP material can be used on rigid blood pump surfaces or on flexible tubings of roller pumps.