Designing Superhydrophobic Robotic Surfaces: Self-Cleaning, High-Grip Impact, and Bacterial Repelling

Abstract Biomimetic surface has attracted a lot of interest in designing the high grip and superhydrophobic surfaces. In particular, adjusting the load on a flexible surface to increase the solid-solid contact area can effectively increase its overall solid-solid static friction. Here we utilized laser processing and hydrochloric acid etching methods on the aluminum alloy substrate surface to generate different textures as templates to produce polydimethylsiloxane (PDMS) films with flexible superhydrophobic surfaces. Four versatile PDMS films with surface morphologies were produced, which gave superhydrophobic properties at varying angles. Scanning electron microscopy revealed that a micron- and nano-scale structure is produced by the etched methods applied here. The static friction and its impact on grip using these flexible superhydrophobic surfaces were further studied under different loads and various conditions. We found that the flexible superhydrophobic surface increased grip under all conditions, using a critical threshold load. The high surface area of superhydrophobic surfaces can increase surface contact and friction. Also, the concave-convex structure can act as a suction cup, increasing the static friction. The designed surfaces were further applied to soft robotic hands, which significantly improved its gripping impact and bacteria-repelling properties after washing.