Trumpet-shaped controllable adhesive structure for manipulation of millimeter-sized objects

Abstract

Reversible adhesion has great potential in a broad range of applications such as robotic grasping, transfer printing, and precision assembling. Herein, we show a trumpet-shaped controllable adhesive structure capable of grasping and releasing millimeter-sized three-dimensional objects with an instability modulation strategy. Experimental results revealed that the strong grasping capacity via compressing derives from the dual contribution of vacuum pressure and van der Waals interactions at the contact interface, whereas the easy releasing performance via shearing/twisting is facilitated by local unsymmetric cracking and subsequent peeling at the adhesive interface. Finite element analysis validated that external load such as shearing and twisting can dynamically modulate the interfacial stress from a relatively uniform distribution to a severely uneven state through buckling, which changes the crack path and thereby destructs the adhesive interface. Furthermore, the controllable adhesive structure was successfully demonstrated to transfer various three-dimensional objects with durable performances in both air and underwater environments. This work presents a generally applicable and dexterous modulation strategy to achieve tunable adhesion for millimeter-scale and even smaller objects, which promotes the understanding and application of controllable adhesion.