Davami Keivan, Zhao Lin, Lu Eric, Cortes John, Lin Chen, Lilley Drew E, Purohit Prashant K, Bargatin Igor
Department of Mechanical Engineering and Applied Mechanics, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Nanotechology Master's Program, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
Nat Commun. 2015 Dec 3;6:10019. doi: 10.1038/ncomms10019.
Unusual mechanical properties of mechanical metamaterials are determined by their carefully designed and tightly controlled geometry at the macro- or nanoscale. We introduce a class of nanoscale mechanical metamaterials created by forming continuous corrugated plates out of ultrathin films. Using a periodic three-dimensional architecture characteristic of mechanical metamaterials, we fabricate free-standing plates up to 2 cm in size out of aluminium oxide films as thin as 25 nm. The plates are formed by atomic layer deposition of ultrathin alumina films on a lithographically patterned silicon wafer, followed by complete removal of the silicon substrate. Unlike unpatterned ultrathin films, which tend to warp or even roll up because of residual stress gradients, our plate metamaterials can be engineered to be extremely flat. They weigh as little as 0.1 g cm(-2) and have the ability to 'pop-back' to their original shape without damage even after undergoing multiple sharp bends of more than 90°.
机械超材料不同寻常的力学性能取决于其在宏观或纳米尺度上精心设计且严格控制的几何结构。我们介绍一类通过用超薄膜形成连续波纹板而制造的纳米级机械超材料。利用机械超材料特有的周期性三维结构，我们用仅25纳米厚的氧化铝薄膜制造出尺寸达2厘米的独立板材。这些板材是通过在光刻图案化的硅片上原子层沉积超薄氧化铝薄膜，随后完全去除硅衬底而形成的。与未图案化的超薄膜不同，未图案化的超薄膜由于残余应力梯度往往会翘曲甚至卷起，而我们的板材超材料经过设计可以极其平整。它们的重量低至0.1克每平方厘米，并且即使在经历多次超过90°的急剧弯曲后仍能“弹回”其原始形状而不损坏。
