Biomimetic Directional Switchable Adhesive Inspired by the Gecko

摘要

We showed how by cleverly engineering asymmetric polymeric microstructures, we could fabricate a reusable switchable gecko-like adhesive yielding steady high adhesive (F_⊥ ≈ 1.25 N/cm~2) and friction (F_‖ ≈ 2.8 N/cm~2) forces when actuated for "gripping", yet release easily with minimal adhesion (F_⊥ ≈ 0.34 N/cm~2) and friction (F_‖ ≈ 0.38 N/cm~2) forces during detachment or "releasing", over multiple attachment/detachment cycles, with a relative small normal preload of 0.16 N/cm~2 to initiate the adhesion. We also demonstrated how these adhesives can be used to reversibly suspend weights from vertical (e.g., walls), and, for the first time to our knowledge, horizontal (e.g., ceilings) surfaces by simultaneously and judiciously activating anisotropic friction and adhesion forces. This design opens the way for new gecko-like adhesive surfaces and articulation mechanisms that do not rely on intensive nanofabrication.