Rapid expulsion of microswimmers by a vortical flow.
Rapid expulsion of microswimmers by a vortical flow.
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DOI：
10.1038/ncomms11114
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发表时间：
2016-03-23
影响因子：
16.6
通讯作者：
Aranson IS
中科院分区：
文献类型：
--
作者：
Sokolov A;Aranson IS
微游泳者与其流体环境的相互作用异常复杂。宏观剪切流动以一种非常重要的方式改变了游泳轨迹，并导致粘度和异质细菌分布的急剧减少。在这里，我们报告了通过旋转微粒产生的涡流快速驱逐微游泳者（如运动细菌）的实验和理论研究。我们观察到在微粒附近的高剪切区形成宏观损耗区。细菌从剪切富区快速迁移是由气流的涡旋结构引起的，而不是细菌方向固有的随机波动，与平面剪切流动形成鲜明对比。我们的数学模型表明，驱逐是由涡旋流的运动性和对齐的综合效应。我们的发现为操纵活动微生物提供了一种新的方法，并阐明了细菌流相互作用。细菌等微游泳者的控制对于活性生物激发材料的新兴应用非常重要。在这里，作者演示了使用涡旋剪切从旋转微粒附近驱逐悬浮的运动细菌。
Interactions of microswimmers with their fluid environment are exceptionally complex. Macroscopic shear flow alters swimming trajectories in a highly nontrivial way and results in dramatic reduction of viscosity and heterogeneous bacterial distributions. Here we report on experimental and theoretical studies of rapid expulsion of microswimmers, such as motile bacteria, by a vortical flow created by a rotating microparticle. We observe a formation of a macroscopic depletion area in a high-shear region, in the vicinity of a microparticle. The rapid migration of bacteria from the shear-rich area is caused by a vortical structure of the flow rather than intrinsic random fluctuations of bacteria orientations, in stark contrast to planar shear flow. Our mathematical model reveals that expulsion is a combined effect of motility and alignment by a vortical flow. Our findings offer a novel approach for manipulation of motile microorganisms and shed light on bacteria–flow interactions. The control of microswimmers such as bacteria is important for emerging applications of active bioinspired materials. Here, the authors demonstrate the use of vortical shear to expel suspended motile bacteria from the vicinity of a rotating microparticle.