Gecko Feet: Natural Hairy Attachment Systems for Smart Adhesion

Abstract

leg attachment pad gecko foot smart adhesion The leg attachment pads of several creatures, including many insects, spiders, and lizards, are capable of attaching to a variety of surfaces and are used for locomotion. Geckoes, in particular, have hairy attachment the largest mass and have developed the most complex hairy attachment structures capable of smart smart adhesion adhesion – the ability to cling to different smooth and rough surfaces and detach at will. These microscale hair animals make use of about three million microscale hairs (setae) (about 14,000 mm−2) that nanoscale spatula branch off into hundreds of nanoscale spatulae (about three billion spatula on two feet). This so-called division of contacts provides high dry adhesion. This multiple-level hierarchically structured surface construction provides the gecko with the compliance and adaptability to create a large real area of contact with a variety of surfaces. Modeling of the gecko attachment system as a hierarchical hierarchical spring model spring model has provided insight into the adhesion enhancement generated by this system. van der Waals forces are the primary mechanism utilized to adhere to surfaces, and capillary forces are a secondary effect that can further increase the adhesion force. Preload applied to the setae increases adhesive force. Although a gecko is capable of producing of the order of 20 N of adhesive force, it retains the ability to remove its feet from an attachment surface at will. The adhesive strength of gecko setae is dependent on orientation; maximum adhesion occurs at 30°. During walking, a gecko is able to peel its foot from surfaces by changing the angle at fibrillar structure which its setae contact the surface. Manmade fibrillar structures capable of replicating gecko adhesion superadhesive tape wall-climbing robot have the potential for use in dry superadhesive tapes and treads for wall-climbing robots for various applications. These structures can be created using micro/nanofabrication techniques or self-assembly.