Magnetically Actuated Patterns for Bioinspired Reversible Adhesion (Dry and Wet)

摘要

Over the last decade the unique "strong but reversible" characteristics of gecko's and tree frog's adhesive pads have been intensively investigated both in the natural systems and artificial mimics. Whereas adhesive strength in the natural systems has been matched and even surpassed with synthetic micro and nanostructured surfaces, strategies to effectively switch between adhesive and non adhesive states, drastically or gradually, are still scarce and limited either in performance or by the complexity of the preparation method. Reversibility in patterned adhesives relies on a significant surface pattern reorganisation via application of an external stimulus. In artificial systems this has been achieved by temperature changes using patterns of responsive polymer materials (shape memory polymers and liquid crystalline polymers or by mechanical stretching of wrinkled patterns supported by elastomeric films. Switching adhesion with temperature based methods is slow and cannot be tuned. Adhesion changes by mechanical forces only work on stretchable films and the principle is not applicable when these are supported by rigid solids. Methods for reversible and tunable adhesion controlled by non-contact external stimuli (temperature, light, etc.) remain a scientific and technical challenge.