Dynamic angular segregation of vesicles in electrohydrodynamic flows.
Dynamic angular segregation of vesicles in electrohydrodynamic flows.
复制标题
电流体动力学流中囊泡的动态角分离。
DOI：
10.1021/la100447m
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发表时间：
2010
期刊：
影响因子：
--
通讯作者：
H. Stone
中科院分区：
文献类型：
--
作者：
W. Ristenpart;Olivier Vincent;S. Lecuyer;H. Stone
我们研究了一种新的行为，即在环形电流体流动中，围绕较大的小泡运行的小泡经历动态的角分离。施加低频(约50赫兹)电场会导致邻近的单层小泡在电极附近聚集，其方式与刚性胶体颗粒的情况相似。然而，对于多分散的囊泡悬浮液，在环形电流体流场中，经常观察到较小的囊泡(<；10微米)围绕较大的囊泡(>；20微米)“轨道”运行。在轨道运行时，较小的囊泡逐渐分离成定义明确的角状横截面。从上面看，小泡似乎在规定的角度上形成动态的“带”，由没有小泡的区域隔开。我们用诱导偶极子相互作用来解释角分离，并提出了一个基于点偶极子在蜂窝流场中旋转的模型。我们证明，该模型产生了令人惊讶的不同范围的囊泡轨迹，包括许多与实验观察定性一致的轨迹。
We investigate a new type of behavior whereby small vesicles orbiting around a larger vesicle in a toroidal electrohydrodynamic flow undergo dynamic angular segregation. Application of a low frequency (approximately 50 Hz) electric field induces aggregation of adjacent unilamellar vesicles near the electrode, in a manner similar to that observed with rigid colloidal particles. For polydisperse vesicle suspensions, however, small vesicles (<10 microm) are often observed to "orbit" around larger vesicles (>20 microm) in a toroidal electrohydrodynamic flow field. While orbiting, the smaller vesicles gradually segregate into well-defined angular cross sections. Viewed from above, the vesicles appear to form dynamic "bands" at prescribed angles, separated by regions devoid of vesicles. We interpret the angular segregation in terms of induced dipolar interactions, and we propose a model based on point dipoles rotating in a cellular flow field. We demonstrate that the model yields a surprisingly diverse range of vesicle trajectories, including many that are qualitatively consistent with the experimental observations.