Centre for Regional and Rural Futures, Deakin University, Geelong, Victoria, 3216, Australia.
Queensland Micro- and Nanotechnology Centre, Griffith University, Nathan, Queensland, 4111, Australia.
Electrophoresis. 2021 Nov;42(21-22):2230-2237. doi: 10.1002/elps.202100126. Epub 2021 Sep 2.
Microfluidic particle focusing has been a vital prerequisite step in sample preparation for downstream particle separation, counting, detection, or analysis, and has attracted broad applications in biomedical and chemical areas. Besides all the active and passive focusing methods in Newtonian fluids, particle focusing in viscoelastic fluids has been attracting increasing interest because of its advantages induced by intrinsic fluid property. However, to achieve a well-defined focusing position, there is a need to extend channel lengths when focusing micrometer-sized or sub-microsized particles, which would result in the size increase of the microfluidic devices. This work investigated the sheathless viscoelastic focusing of particles and cells in a zigzag microfluidic channel. Benefit from the zigzag structure of the channel, the channel length and the footprint of the device can be reduced without sacrificing the focusing performance. In this work, the viscoelastic focusing, including the focusing of 10 μm polystyrene particles, 5 μm polystyrene particles, 5 μm magnetic particles, white blood cells (WBCs), red blood cells (RBCs), and cancer cells, were all demonstrated. Moreover, magnetophoretic separation of magnetic and nonmagnetic particles after viscoelastic pre-focusing was shown. This focusing technique has the potential to be used in a range of biomedical applications.
微流控粒子聚焦是下游粒子分离、计数、检测或分析的样品制备的重要前提步骤，在生物医学和化学领域得到了广泛的应用。除了牛顿流体中的所有主动和被动聚焦方法外，由于其固有流体特性引起的优势，粘弹性流体中的粒子聚焦也引起了越来越多的关注。然而，为了实现明确的聚焦位置，需要在聚焦微米级或亚微米级粒子时延长通道长度，这会导致微流控器件的尺寸增大。本工作研究了在曲折微流道中无鞘粘弹性粒子和细胞的聚焦。得益于通道的曲折结构，在不牺牲聚焦性能的情况下，可以减小通道长度和器件的占地面积。在这项工作中，展示了粘弹性聚焦，包括 10μm 聚苯乙烯粒子、5μm 聚苯乙烯粒子、5μm 磁性粒子、白细胞 (WBC)、红细胞 (RBC) 和癌细胞的聚焦。此外，还展示了粘弹性预聚焦后磁性和非磁性粒子的磁分离。这种聚焦技术有可能在一系列生物医学应用中得到应用。
