Abstract
Compared with conventional manipulating methods, such as vacuum suction, electromagnetic adsorption, and mechanical clamping, gecko-inspired adhesives possess the ability of attaching on various surfaces with extensive applications in space operation, industrial manufacturing, etc. However, adhesive structures with high adhesion on one certain surface may lose their adhesive performance when gripping another surface. Achieving a good adhesion on objects with unknown surface morphology in a simple way is still a great challenge for gecko-inspired adhesives. Inspired by the interaction of the gecko's actuating muscle and adhesive structures, we propose a smart adhesive film to adaptively manipulate objects with unknown surface morphology, consisting of magnetic artificial muscle and mushroom-shaped structures at the microscale. Controlled by the magnetic field, the adhesive film can conformally contact the target surfaces with flat/curved morphology or smooth/rough topography, and easily separated from the contacting interfaces, which process is performed without complex image recognition or detection sensors on pre-determining the detailed morphology of the opposing surfaces. This specific characteristic enables the smart adhesive film to successfully grip, transfer and release the unknown objects, extending the operating specification of gecko-inspired adhesives. Especially, in the manipulating process, the objects would not be dropped down from the smart adhesive film even if the magnetic field is suddenly removed, which is seldom achieved by other soft grippers. The proposed adhesion strategy extends gecko-inspired adhesives from specific types of surfaces to unknown surface morphology, opening an avenue for the development of gecko-inspired adhesive-based devices and systems.