Ben Zion Matan Yah, Caba Yaelin, Modin Alvin, Chaikin Paul M
Center for Soft Matter Research, Department of Physics, New York University, 726 Broadway Avenue, New York, NY, 10003, USA.
UMR Gulliver 7083 CNRS, ESPCI Paris, PSL Research University, 10 rue Vauquelin, 75005, Paris, France.
Nat Commun. 2022 Jan 10;13(1):184. doi: 10.1038/s41467-021-27870-9.
While motile bacteria display rich dynamics in dense colonies, the phoretic nature of artificial micro-swimmers restricts their activity when crowded. Here we introduce a new class of synthetic micro-swimmers that are driven solely by light. By coupling a light absorbing particle to a fluid droplet we produce a colloidal chimera that transforms optical power into propulsive thermo-capillary action. The swimmers' internal drive allows them to operate for a long duration (days) and remain active when crowded, forming a high density fluid phase. We find that above a critical concentration, swimmers form a long lived crowded state that displays internal dynamics. When passive particles are introduced, the dense swimmer phase can re-arrange to spontaneously corral the passive particles. We derive a geometrical, depletion-like condition for corralling by identifying the role the passive particles play in controlling the effective concentration of the micro-swimmers.
虽然运动性细菌在密集菌落中表现出丰富的动态行为，但人工微游动器的泳动特性在拥挤时会限制其活性。在此，我们引入了一类全新的仅由光驱动的合成微游动器。通过将一个光吸收粒子与一个液滴耦合，我们制造出一种胶体嵌合体，它能将光能转化为推进性的热毛细作用。这些游动器的内部驱动使其能够长时间（数天）运行，并且在拥挤时仍保持活跃，形成高密度流体相。我们发现，在超过临界浓度时，游动器会形成一种具有内部动态的长期拥挤状态。当引入被动粒子时，密集的游动器相能够重新排列以自发地圈围被动粒子。通过确定被动粒子在控制微游动器有效浓度中所起的作用，我们推导出了一个用于圈围的几何类似耗尽的条件。
