Center for Biofluid and Biomimic Research, Department of Mechanical Engineering, WCU program Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, 790-784, Korea.
Lab Chip. 2011 Feb 7;11(3):460-5. doi: 10.1039/c0lc00212g. Epub 2010 Nov 12.
The inertial migration of particles in micro-scale flows has received much attention due to its promising applications, such as the membrane-free passive separation of particles or cells. The particles suspended in rectangular channels are known to be focused near the center of each channel face as the channel Reynolds number (R(C)) increases due to the lift force balance and the hydrodynamic interactions of the particles with the wall. In this study, the three-dimensional positions of neutrally buoyant spherical particles inside a square microchannel are measured using the digital holographic microscopy technique, and a transition from the lateral tubular pinch to the cross-lateral focusing with increasing R(C) is reported. The particles are found to migrate first in the lateral direction and then cross-laterally toward the four equilibrium positions. A general criterion that can be used to secure the fully developed state of particle focusing in Lab-on-a-Chip applications is also derived. This criterion could be helpful for the accurate estimation of the design parameters of inertial microfluidic devices, such as R(C), channel length and width, and particle diameter.
由于其在膜自由的颗粒或细胞被动分离等方面具有广阔的应用前景，微尺度流场中颗粒的惯性迁移受到了广泛关注。当通道雷诺数（R(C)）增加时，由于升力平衡和颗粒与壁面的流体动力相互作用，悬浮在矩形通道中的颗粒会集中在每个通道面的中心附近。在这项研究中，使用数字全息显微镜技术测量了方微通道内中性浮力球形颗粒的三维位置，并报告了随着 R(C) 的增加，从横向管状挤压到横向交叉聚焦的转变。发现颗粒首先在横向方向迁移，然后横向迁移到四个平衡位置。还推导出了一个可以用于确保在芯片实验室应用中颗粒聚焦完全发展状态的一般准则。该准则有助于对惯性微流控器件的设计参数（如 R(C)、通道长度和宽度以及颗粒直径）进行准确估计。
