Mushroom-Shaped Adhesive Structures with Smooth Contour via Electrical Growth.

Bioinspired dry adhesives based on van der Waals forces have a wide range of impact in space operations, robot manipulation, and other fields. Previous studies have confirmed the significant advantages of a mushroom-shaped structure in uniformly distributing the separation stress. However, most of them are based on the structure with an abrupt geometric contour and have neglected the effect of a smooth contour on the contact process. Here, we analyze the effect mechanism of geometric contours on the contact-separation behavior of mushroom-shaped adhesive structures by finite element analysis and investigate the enhancement of smooth contours on the adhesive properties of mushroom-shaped structures. On this basis, we propose a one-step forming strategy inspired by the growth mechanism of biological adhesive structures to obtain mushroom-shaped structures with smooth contours by flow forming. The mushroom-shaped structures with smooth contours exhibit more excellent adhesive performance than those with mutant contours in the adhesion test, which verifies the correctness of our proposed law of geometric contours' influence on adhesive behavior, providing a new idea for the design of dry adhesives and dry adhesive-based systems.