Bioinspired micropatterned adhesives – from micromechanics to robotic function

3D micropatterning of surfaces signifies a recent paradigm shift for control of surface functionalities: the exploitation of judiciously designed surface protrusions, “fibrils” and other features at the micron scale. This talk will give an overview of our successful attempts to create bioinspired adhesive surfacesby micropatterning, with special emphasis on mechanisms and modeling. Interesting size effects appear in adhesion, both on the level of single fibrils and on the higher level of hierarchy of single arrays. Our principle of "contact splitting“, i.e. the gain in intermolecular adhesion due to a multitude of fine fibrillar contacts instead of one monolithic contact region, allows good Van der Waals contact between the surfaces while establishing little elastic strain. We have also shown that a switching action to a non-adhesive state can reproducibly achieved, for example, by inducing bending and Euler buckling in the fibrils. An important element of our work is the numerical simulation of the adhesion performance as a function of materials and structure parameters, which has allowed us to rationally optimize our structures for particular applications. More recently, we have extended our adhesive systems to address also biological surfaces, especially skin. These properties make gecko surfaces interesting for innovative surgical procedures. Currently, these principles are being exploited to create new surface solutions for robotic pick-and-place systems, assembly machines, in space technology and biomedicine.