Nature-inspired fibrillar adhesives have versatile applications, such as wall-climbing robots
and grippers, which require residue-free and repeatable adhesion. To meet the
requirements of excellent adhesion strength combined with controllability of adhesion and
detachment, directional adhesive pillars with anisotropic adhesion properties have been
extensively investigated. However, existing designs that simply mimic nature suffer from
relatively weak adhesion and insufficient directionality, because most of them were …