Flexible carbon-nanofiber connectors with anisotropic adhesion properties.

The ability of gecko lizards and many insects to climb vertical surfaces relies on the hierarchical microand nanofibrillar arrayed features on their feet. The fibrillar structures provide conformal contact with the opposing surfaces to maximize the van der Waals (vdW) interactions. These adhesive systems found in nature have inspired researchers to design synthetic adhesives by using fibrillar arrays of polymers andcarbonnanotubes (CNTs),whichcanuniversally attach toa variety of surfaces. In addition to these universal adhesives, the fibrillar arrays have also been utilized to design self-selective connectors to bind morphologically self-similar components together. Specifically, we recently reported selfselective connectors based on inorganic/organic nanowire (NW) arrays, in which the vdW interactions are significantly amplified by the interpenetration of the high-aspect-ratio NW components. In contrast to gecko adhesives, the unisex NW connectors feature self-selective binding with weak adhesion to non-self-similar surfaces arising from the relatively stiff structure of the hybrid NWs.While the potency of the NW connectors has been shown, previous studies have relied on hard and fragile backing layers, such as silicon substrates used for the growth of the inorganic NWs, which is not practical for