Gecko-Inspired Dry Adhesive Based on Micro-Nanoscale Hierarchical Arrays for Application in Climbing Devices
Gecko-Inspired Dry Adhesive Based on Micro-Nanoscale Hierarchical Arrays for Application in Climbing Devices
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DOI：
10.1021/acsami.7b09526
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发表时间：
2018-01-10
影响因子：
9.5
通讯作者：
Wood, Kristin L.
中科院分区：
文献类型：
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作者：
Raut, Hemant Kumar;Baji, Avinash;Wood, Kristin L.
壁虎攀爬垂直墙壁的非凡能力是分层结构设计和更坚硬的材料成分的独特组合的基础。虽然密集的微观分层结构使壁虎脚趾垫能够粘附到各种表面，但更硬的材料（β-角蛋白）成分使它们能够在无数次循环中保持可靠的粘附力。这种独特的策略很少在工程干粘合剂中实施，因为使用更硬的聚合物制造高纵横比的分层结构具有挑战性。在此，我们报告了通过牺牲层介导的纳米压印技术在柔性聚碳酸酯片材（硬度与β角蛋白相当）上制造高纵横比的分层阵列。包含分层阵列的干粘合膜显示出 11.91 +/- 0.43 N/cm(2) 的强大剪切粘合力。循环粘合力测试还表明，50次循环后，粘合膜的剪切粘合力仅降低约20%，并且在约200次循环之前保持几乎恒定。最重要的是，高纵横比分层阵列被集成到微型机器人的脚上，并演示了在 30° 倾斜表面上的运动。
The unusual ability of geckos to climb vertical walls underlies a unique combination of a hierarchical structural design and a stiffer material composition. While a dense array of microscopic hierarchical structures enables the gecko toe pads to adhere to various surfaces, a stiffer material (beta-keratin) composition enables them to maintain reliable adhesion over innumerable cycles. This unique strategy has been seldom implemented in engineered dry adhesives because fabrication of high-aspect-ratio hierarchical structures using a stiffer polymer is challenging. Herein, we report the fabrication of high-aspect-ratio hierarchical arrays on flexible polycarbonate sheets (stiffness comparable to that of beta keratin) by a sacrificial-layer-mediated nanoimprinting technique. Dry-adhesive films comprising the hierarchical arrays showed a formidable shear adhesion of 11.91 +/- 0.43 N/cm(2). Cyclic adhesion tests also showed that the shear adhesion of the adhesive films reduced by only about 20% after 50 cycles and remained nearly constant until about 200 cycles. Most importantly, the high-aspect-ratio hierarchical arrays were integrated onto the feet of a miniature robot and the locomotion on a 30 inclined surface was demonstrated.