Wet soft bio-adhesion of insect-inspired polymeric oil-loadable perforated microcylinders

Insect adhesion systems can enhance adhesion forces on wet or rough surfaces via oil-loadable spherical chambers and mushroom-shaped tips, enabling the achievement of an improved suction effect. In addition, highly conformal polymeric bio-adhesives with multiscale 3-dimensional (3D) architectures have been developed for stable adhesion performance on soft, wet, and non-flat skin or organ tissue. In this work, we propose a highly adaptable, biofluid-controllable, and reversible bio-adhesive with enhanced pulling adhesion and omnidirectional shear resistance. The development of this bio-adhesive was inspired by the hairy structure found in diving beetles, characterized by an oil-loadable spherical suction chamber and a mushroom-shaped tip. By investigating various geometrical and material parameters, a novel fabrication method was developed to control the diameter of the spherical chambers within the microcylinders and to create mushroom-like tips on the micropillars with 3D chambers. Owing to the capillarity-assisted suction effect and the omnidirectional shear resistance, originated from structural and materials features, the proposed bioinspired adhesive exhibits improved adhesion against dry and wet skin, as well as organ surfaces. Furthermore, diving beetle-inspired adhesives were employed on the top surfaces of a surgical grasper to utilize bioinspired architectures as highly conformal, wet-tolerant adhesive elements to minimize the damage of the engaged liver surfaces.