Spontaneous self-propulsion and nonequilibrium shape fluctuations of a droplet enclosing active particles
Spontaneous self-propulsion and nonequilibrium shape fluctuations of a droplet enclosing active particles
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DOI：
10.1038/s42005-022-00872-9
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发表时间：
2022-04-14
影响因子：
5.5
通讯作者：
Vlahovska, Petia M.
中科院分区：
文献类型：
--
作者：
Kokot, Gasper;Faizi, Hammad A.;Vlahovska, Petia M.
活性粒子，如游动细菌或自推进胶体，自发地组装成大规模的动态结构。几何边界往往强制不同的时空模式相比，开放的环境，从而提供了一个平台，以控制活动的物质的行为。在这里，我们报告的集体动力学的活性粒子封闭的软，可变形的边界，这是响应于粒子的活动。我们发现，一个准二维的流体液滴封闭动力的Quincke效应（Quincke辊）具有强烈的形状波动与功率谱一致的主动波动驱动的颗粒界面碰撞。打破详细的平衡证实了形状动力学的非平衡性质。我们进一步发现，辊自组织成一个单一的滴跨越涡，它可以经历一个自发的对称性破缺和涡分裂。当涡偶存在时，液滴获得运动性。我们的研究结果提供了深入了解复杂的集体行为的活性胶体悬浮液在软约束。
Active particles, such as swimming bacteria or self-propelled colloids, spontaneously assemble into large-scale dynamic structures. Geometric boundaries often enforce different spatio-temporal patterns compared to unconfined environment and thus provide a platform to control the behavior of active matter. Here, we report collective dynamics of active particles enclosed by soft, deformable boundary, that is responsive to the particles' activity. We reveal that a quasi two-dimensional fluid droplet enclosing motile colloids powered by the Quincke effect (Quincke rollers) exhibits strong shape fluctuations with a power spectrum consistent with active fluctuations driven by particle-interface collisions. A broken detailed balance confirms the nonequilibrium nature of the shape dynamics. We further find that rollers self-organize into a single drop-spanning vortex, which can undergo a spontaneous symmetry breaking and vortex splitting. The droplet acquires motility while the vortex doublet exists. Our findings provide insights into the complex collective behavior of active colloidal suspensions in soft confinement.