Functional microstructures inspired by nature: from mechanics to new materials for robotics and biomedicine

Evolution has evolved fascinating resource-efficient materials architectures to solve mechanical problems. In this talk, I will review the mechanics of gripping like a gecko, which is mainly due to van der Waals interactions mediated by microfibrillar (‘hairy’) structures. After more than a decade of focused work in this area, we have recently developed release mechanisms for micro-objects with negligible mass, which are otherwise difficult to detach. Implementation in robotic pick-and-place applications has led to a machine-learning concept based on optical monitoring, which is designed to accelerate industrial acceptance of this new technology. As a serendipitous development, we have adapted such adhesive structures to stick to skin, which has led to a clinical adhesive for ear surgery. A new concept from Nature is the optimization of ‘stingers’ for easy penetration. It will be shown that sharp stingers, with sizes ranging from microns to millimeters, solve the conflict between buckling and penetration by adopting a ‘universal’ parabolic shape with an exponent close to 2. Analysis of these competing processes identifies a window of shapes in which penetration always precedes buckling. These examples highlight Nature’s need to ‘design’ and ‘optimize’ by geometric or structural variation as it has, compared to engineers, access to only relatively few high-performance materials.