Zhu Guangdong, Alexeev Alexander, Kumacheva Eugenia, Balazs Anna C
Chemical Engineering Department, University of Pittsburgh, Pittsburgh, Pennsylvania 15261, USA.
J Chem Phys. 2007 Jul 21;127(3):034703. doi: 10.1063/1.2753150.
Using a computational model, we investigate the motion of microcapsules inside a microchannel that encompasses a narrow constriction. The microcapsules are composed of a compliant, elastic shell and an encapsulated fluid; these fluid-filled shells model synthetic polymeric microcapsules or biological cells (e.g., leukocytes). Driven by an imposed flow, the capsules are propelled along the microchannel and through the constricted region, which is formed by two pillars that lie in registry, extending from the top and bottom walls of the channels. The tops of these pillars (facing into the microchannel) are modified to exhibit either a neutral or an attractive interaction with the microcapsules. The pillars (and constriction) model topological features that can be introduced into microfluidic devices or the physical and chemical heterogeneities that are inherently present in biological vessels. To simulate the behavior of this complex system, we employ a hybrid method that integrates the lattice Boltzmann model (LBM) for fluid dynamics and the lattice spring model (LSM) for the micromechanics of elastic solids. Through this LBM/LSM technique, we probe how the capsule's stiffness and interaction with the pillars affect its passage through the chambers. The results yield guidelines for regulating the movement of microcarriers in microfluidic systems and provide insight into the flow properties of biological cells in capillaries.
我们使用一个计算模型来研究微胶囊在包含狭窄收缩部分的微通道内的运动。微胶囊由一个柔顺的弹性外壳和一种被包裹的流体组成；这些充满流体的外壳模拟合成聚合物微胶囊或生物细胞（例如白细胞）。在施加的流场驱动下，微胶囊沿着微通道推进并通过由两个对齐的柱子形成的收缩区域，这两个柱子从通道的顶壁和底壁延伸出来。这些柱子的顶部（面向微通道内部）经过修饰，以与微胶囊呈现中性或吸引性相互作用。柱子（和收缩部分）模拟了可以引入微流控装置的拓扑特征，或者生物血管中固有的物理和化学异质性。为了模拟这个复杂系统的行为，我们采用了一种混合方法，该方法将用于流体动力学的格子玻尔兹曼模型（LBM）和用于弹性固体微观力学的格子弹簧模型（LSM）相结合。通过这种LBM/LSM技术，我们探究了微胶囊的刚度以及与柱子的相互作用如何影响其通过腔室的过程。研究结果为调节微流控系统中微载体的运动提供了指导方针，并深入了解了毛细血管中生物细胞的流动特性。
