Optimal design of a bioinspired micropillar arrayed surface for equal load sharing and robust adhesion

Simultaneous detachment of all microstructures during the loading process, known as equal load sharing (ELS), can ensure the robust adhesion of a microstructural surface. Inspired by gecko adhesion, although various fibrillar structured surfaces had been fabricated to mimic gecko adhesion, robust adhesion is not easily achieved because of the load concentration at the edge fibrils of the microstructural surface. In this paper, an optimal design strategy is proposed to analyze the factors affecting the interface adhesion. It is found that the height, radius, and elastic modulus of the micropillars and the elastic modulus of the backing layer can be well optimized into specific non-uniform distributions, achieving ELS of all the micropillars at interface detachment, thereby leading to robust adhesion of micropillar arrayed surfaces. Furthermore, the non-uniform distribution functions of the micropillar’s height, radius, and Young’s modulus are well achieved analytically and verified by the finite element simulations. The proposed optimal design methods can also be applied to other fibrillar geometries, for example, mushroom-shaped fibrillar arrays. The obtained results would be very helpful for the design of robust adhesion of gecko-inspired microstructural adhesives.