Li Xinzhi, Bi Dapeng
Department of Physics, Carnegie Mellon University, Pittsburgh, PA 15213, USA.
Department of Physics, Northeastern University, Boston, MA 02115, USA.
Soft Matter. 2023 Nov 1;19(42):8221-8227. doi: 10.1039/d3sm00419h.
We introduce an amorphous mechanical metamaterial inspired by how cells pack in biological tissues. The spatial heterogeneity in the local stiffness of these materials has been recently shown to impact the mechanics of confluent biological tissues and cancer tumor invasion. Here we use this bio-inspired structure as a design template to construct mechanical metamaterials and show that this heterogeneity can give rise to amorphous cellular solids with large, tunable acoustic bandgaps. Unlike acoustic crystals with periodic structures, the bandgaps here are directionally isotropic and robust to defects due to their complete lack of positional order. Possible ways to manipulate bandgaps are explored with a combination of the tissue-level elastic modulus and local stiffness heterogeneity of cells. To further demonstrate the existence of bandgaps, we dynamically perturb the system with an external sinusoidal wave in the perpendicular and horizontal directions. The transmission coefficients are calculated and show valleys that coincide with the location of bandgaps. Experimentally this design should lead to the engineering of self-assembled rigid acoustic structures with full bandgaps that can be controlled mechanical tuning and promote applications in a broad area from vibration isolations to mechanical waveguides.
我们介绍了一种受细胞在生物组织中堆积方式启发的非晶态机械超材料。最近研究表明，这些材料局部刚度的空间异质性会影响融合生物组织的力学性能以及癌症肿瘤的侵袭。在此，我们将这种受生物启发的结构用作设计模板来构建机械超材料，并表明这种异质性能够产生具有大的、可调节声子带隙的非晶态细胞固体。与具有周期性结构的声子晶体不同，这里的带隙在方向上是各向同性的，并且由于完全缺乏位置有序性而对缺陷具有鲁棒性。我们结合细胞的组织水平弹性模量和局部刚度异质性，探索了操纵带隙的可能方法。为了进一步证明带隙的存在，我们用外部正弦波在垂直和水平方向上动态扰动系统。计算得到的传输系数显示出与带隙位置重合的谷值。在实验上，这种设计应该能够实现具有全带隙的自组装刚性声学结构的工程化，这些带隙可以通过机械调谐来控制，并促进从隔振到机械波导等广泛领域的应用。
