Faculty of Science , Hokkaido University , Sapporo 060-0810 , Japan.
Department of Computer Science , Tokyo Institute of Technology , Yokohama 226-8502 , Japan.
ACS Nano. 2019 Nov 26;13(11):12452-12460. doi: 10.1021/acsnano.9b01450. Epub 2019 Oct 17.
Boundary conditions are important for pattern formation in active matter. However, it is still not well-understood how alterations in the boundary conditions (dynamic boundary conditions) impact pattern formation. To elucidate the effect of dynamic boundary conditions on the pattern formation by active matter, we investigate an gliding assay of microtubules on a deformable soft substrate. The dynamic boundary conditions were realized by applying mechanical stress through stretching and compression of the substrate during the gliding assay. A single cycle of stretch-and-compression (relaxation) of the substrate induces perpendicular alignment of microtubules relative to the stretch axis, whereas repeated cycles resulted in zigzag patterns of microtubules. Our model shows that the orientation angles of microtubules correspond to the direction to attain smooth movement without buckling, which is further amplified by the collective migration of the microtubules. Our results provide an insight into understanding the rich dynamics in self-organization arising in active matter subjected to time-dependent boundary conditions.
边界条件对于活性物质中的模式形成很重要。然而，对于边界条件（动态边界条件）的改变如何影响模式形成，人们仍然了解甚少。为了阐明动态边界条件对活性物质模式形成的影响，我们研究了在可变形软基底上滑行的微管。通过在滑行实验过程中拉伸和压缩基底来实现动态边界条件。基底的单次拉伸-压缩（松弛）循环会引起微管相对于拉伸轴的垂直排列，而重复循环则会导致微管呈现之字形图案。我们的模型表明，微管的取向角对应于达到无屈曲平滑运动的方向，而微管的集体迁移进一步放大了这个方向。我们的结果提供了一种理解在受时间相关边界条件影响的活性物质中出现的丰富自组织动力学的思路。
