基于变截面微通道的黏弹性流体内颗粒高效分离研究

Efficient Separation of Microparticles in Viscoelastic Fluid via Microchannel WithVariable Cross Section

黏弹性流体广泛存在于自然界中,如人体中的血液等。实现黏弹性流体中不同尺寸微颗粒的高效分离对于生命科学和临床医学等领域有着重要的意义。本文基于对黏弹性流体中的微颗粒先富集再分离的思想,首先通过渐缩截面微通道,改变弹性升力的方向,并增强微颗粒在微通道中的受力,实现不同微颗粒的高效富集。而后,利用不同粒径微颗粒在层流状态下的运动特性差异,进一步实现对不同尺寸微颗粒的高效分离。实验结果表明,在维森伯格数Wi为17.5至34.9的范围内,聚乙烯吡咯烷酮(PVP)黏弹性流体中10 μm与4 μm两种微颗粒可实现完全分离。此外,本文还研究了不同流动参数和通道几何结构对黏弹性流体中颗粒分离的影响。与其他用于黏弹性流体中微颗粒分离的微流控技术相比,本文提出的颗粒分离方法具有分离精度和效率高、通道长度短等优点。基于此方法的微流控芯片技术在生物医学等领域有着巨大的应用潜力。

The viscoelastic fluid widely exists in the nature, such as the human blood. Efficientseparation of the microparticles suspended in the viscoelastic fluid has great potentials in the lifescience and the clinical fields. Based on the concept to focus and then to separate the microparticles,the efficient viscoelastic focusing of the microparticle was firstly achieved in a microchannel withgradually contracted cross section which significantly enhanced the driving forces on the particle.Then microparticles were separated based on the different migration behavior of the particle withdifferent sizes in laminar flow. The experiment results demonstrated that, when the Weissenbergnumber Wi was from 17.5 to 34.9, the 10 µm and 4 µm microparticles suspended in the PolyvinylPyrrolidone (PVP) solution can be completely separated. In addition, the influence of the flowcondition and the channel geometry on the particle separation was also investigated in this paper. Incomparison to the existing microfluidic methods for the viscoelastic separation of the microparticle,the preset method has the advantages of higher separation efficiency and precision, and the shorterchannel length, which makes it more suitable for the biomedical applications.