Prohm Christopher, Stark Holger
Institute of Theoretical Physics, Technische Universität Berlin, Hardenbergstr. 36, 10623 Berlin, Germany.
Lab Chip. 2014 Jun 21;14(12):2115-23. doi: 10.1039/c4lc00145a. Epub 2014 May 8.
Inertial microfluidics is a promising tool for many lab-on-a-chip applications. Particles in channel flows with Reynolds numbers above one undergo cross-streamline migration to a discrete set of equilibrium positions in square and rectangular channel cross sections. This effect has been used extensively for particle sorting and the analysis of particle properties. Using the lattice Boltzmann method, we determined the equilibrium positions in square and rectangular cross sections and classify their types of stability for different Reynolds numbers, particle sizes, and channel aspect ratios. Our findings thereby help to design microfluidic channels for particle sorting. Furthermore, we demonstrated how an axial control force, which slows down the particles and shifts the stable equilibrium position towards the channel center. Ultimately, the particles then stay on the centerline for forces exceeding the threshold value. This effect is sensitive to the particle size and channel Reynolds number and therefore suggests an efficient method for particle separation. In combination with a hysteretic feedback scheme, we can even increase the particle throughput.
惯性微流控技术是一种在许多芯片实验室应用中颇具前景的工具。在雷诺数大于1的通道流中，粒子会发生跨流线迁移，在方形和矩形通道横截面中迁移到一组离散的平衡位置。这种效应已被广泛用于粒子分选和粒子特性分析。我们使用格子玻尔兹曼方法确定了方形和矩形横截面中的平衡位置，并针对不同的雷诺数、粒子尺寸和通道纵横比分类了它们的稳定性类型。我们的研究结果有助于设计用于粒子分选的微流控通道。此外，我们展示了轴向控制力如何使粒子减速并将稳定平衡位置向通道中心移动。最终，当力超过阈值时，粒子会停留在中心线上。这种效应对粒子尺寸和通道雷诺数敏感，因此提出了一种有效的粒子分离方法。结合滞后反馈方案，我们甚至可以提高粒子通量。
