Chinese Academy of Sciences Key Laboratory of Bio-Inspired Materials and Interfacial Science, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, 100190 Beijing, People's Republic of China.
Beijing National Laboratory for Molecular Sciences, Key Laboratory of Green Printing, Institute of Chemistry, Chinese Academy of Sciences, 100190 Beijing, People's Republic of China.
Proc Natl Acad Sci U S A. 2018 Oct 2;115(40):10046-10051. doi: 10.1073/pnas.1808293115. Epub 2018 Sep 17.
Bird feathers have aroused tremendous attention for their superdurability against tears during long flights through wind and even bushes. Although feathers may inevitably be unzipped, the separated feather vanes can be repaired easily by bill stroking. However, the mechanism underlying bird feathers' superdurability against tears remains unclear. Here, we reveal that the superdurability of bird feathers arises from their repairable cascaded slide-lock system, which is composed of hooklets, a slide rail, and spines at the end of the slide rail as terminating structures. Microscopy with a micronano manipulating system and 3D X-ray microscopy provided high-level visibility into the 3D fine structures and the entire unzipping process of feathers. The hooklets can slide along the slide rail reversibly when suffering external forces, and the sliding hooklet can be locked by the spine at the ends of barbules when larger pulling forces are applied and even slide farther away due to the unzipping of the interlocking structure with large deformation of the barbules. The elongation before separation of adjacent barbs can reach up to 270%, and the separation force can be maintained above 80% of the initial value even after 1,000 cycles of separating and repairing. These results prove that the cascaded slide-lock system ensures the superdurability of bird feathers against tears.
鸟类的羽毛具有超强的耐用性，在长途飞行中能抵御风的撕裂，甚至能穿越灌木丛，这引起了人们极大的关注。尽管羽毛可能不可避免地会被拉开，但通过喙的轻抚，分离的羽片可以很容易地被修复。然而，鸟类羽毛具有超强耐用性的机制尚不清楚。在这里，我们揭示了鸟类羽毛的超强耐用性来自于其可修复的级联滑动锁定系统，该系统由钩状结构、滑动轨以及滑动轨末端的刺作为终止结构组成。使用微米纳米操纵系统和 3D X 射线显微镜进行的显微镜检查提供了对羽毛 3D 精细结构和整个拉开过程的高可见度。当受到外力时，钩状结构可以沿着滑动轨可逆地滑动，当施加更大的拉力时，滑动的钩状结构可以被羽枝末端的刺锁定，甚至可以由于互锁结构的拉开而进一步滑动，导致羽枝发生大变形。相邻羽枝分离前的伸长率可达 270%，即使在 1000 次分离和修复循环后，分离力仍能保持在初始值的 80%以上。这些结果证明，级联滑动锁定系统确保了鸟类羽毛的超强耐用性，使其能够抵御撕裂。
