Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, Geesthacht, 21502, Germany.
Institute of Experimental and Applied Physics, Kiel University, Kiel, 24098, Germany.
Adv Mater. 2020 Sep;32(37):e2002758. doi: 10.1002/adma.202002758. Epub 2020 Aug 2.
Wandering spiders climb vertically and walk upside-down on rough and smooth surfaces using a nanostructured attachment system on their feet. The spiders are assumed to adhere by intermolecular van der Waals forces between the adhesive structures and the substrate. The adhesive elements are arranged highly ordered on the hierarchically structured attachment hair (setae). While walking, it has been suggested that the spiders apply a shear force on their legs to increase friction. However, the detailed mechanical behavior of the hair's structures during attachment and detachment remains unknown. Here, gradients of the mechanical properties of the attachment hair on different length scales that have evolved to support attachment, stabilize adhesion in contact, and withstand high stress at detachment, examined by in situ experiments, are shown. Shearing helps to self-align the adhesive elements with the substrate. The study is anticipated to contribute to the development of optimized artificial dry adhesives.
游走蜘蛛利用脚部的纳米结构附着系统在粗糙和光滑表面上垂直攀爬和倒走。据推测，蜘蛛通过附着结构和基质之间的分子间范德华力来附着。附着元件在分层结构的附着毛（刚毛）上高度有序排列。在行走过程中，有人提出蜘蛛会对腿部施加剪切力以增加摩擦力。然而，毛发结构在附着和脱离过程中的详细力学行为仍然未知。本文通过原位实验，展示了不同长度尺度上的附着毛力学性能梯度，这些梯度是为了支持附着、稳定接触中的附着力以及承受脱离时的高应力而进化的。剪切有助于使附着元件与基底自动对齐。该研究有望为优化的人造干式粘合剂的发展做出贡献。
