To locomote on different surfaces, animals have evolved different strategies. Many animals use reversible adhesion for their locomotion, which is largely dependent on the microstructure on the surface of their feet. The micropillar array surfaces inspired by these microstructures therefore are referred to as structured adhesives. In contrast to the use of phase transition of materials to achieve controlled regulation of adhesion, the reversible process of structured adhesive does not require additional energy input. Learning from the energy-saving strategy of structured adhesive, we prepared a series of micropillar arrays with modulus gradient, hard-core soft-shell structure, and micro-nanopit at the micropillar end. These structures can effectively regulate the stress distribution at the separation interface, inhibit the initiation and propagation of cracks, and thus improve the adhesion performance. The asymmetrical design of the micropillars allows for directional adhesion to water droplets and solid surfaces, extending the application of structured adhesion surfaces to the fields of droplet manipulation and soft robotics.
 

Adhesion, bioinspired material, elastic modulus, microstructure