Maria M Sneha, Kumar B S, Chandra T S, Sen A K
Department of Mechanical Engineering, Indian Institute of Technology Madras, Chennai, 600036, India.
Department of Biotechnology, Indian Institute of Technology Madras, Chennai, 600036, India.
Biomed Microdevices. 2015 Dec;17(6):115. doi: 10.1007/s10544-015-0017-z.
This work presents design, fabrication and test of a microfluidic device which employs Fahraeus-Lindqvist and Zweifach-Fung effects for cell concentration and blood cell-plasma separation. The device design comprises a straight main channel with a series of branched channels placed symmetrically on both sides of the main channel. The design implements constrictions before each junction (branching point) in order to direct cells that would have migrated closer to the wall (naturally or after liquid extraction at a junction) towards the centre of the main channel. Theoretical and numerical analysis are performed for design of the microchannel network to ensure that a minimum flow rate ratio (of 2.5:1, main channel-to-side channels) is maintained at each junction and predict flow rate at the plasma outlet. The dimensions and location of the constrictions were determined using numerical simulations. The effect of presence of constrictions before the junctions was demonstrated by comparing the performances of the device with and without constrictions. To demonstrate the performance of the device, initial experiments were performed with polystyrene microbeads (10 and 15 μm size) and droplets. Finally, the device was used for concentration of HL60 cells and separation of plasma and cells in diluted blood samples. The cell concentration and blood-plasma purification efficiency was quantified using Haemocytometer and Fluorescence-Activated Cell Sorter (FACS). A seven-fold cell concentration was obtained with HL60 cells and a purification efficiency of 70 % and plasma recovery of 80 % was observed for diluted (1:20) blood sample. FACS was used to identify cell lysis and the cell viability was checked using Trypan Blue test which showed that more than 99 % cells are alive indicating the suitability of the device for practical use. The proposed device has potential to be used as a sample preparation module in lab on chip based diagnostic platforms.
这项工作展示了一种微流控装置的设计、制造和测试，该装置利用法厄斯-林德奎斯特效应和茨魏法赫-冯效应进行细胞浓缩和血细胞-血浆分离。该装置设计包括一条直的主通道，在主通道两侧对称设置一系列分支通道。该设计在每个连接处（分支点）之前设置收缩部分，以便将那些原本会迁移到更靠近壁面（自然迁移或在连接处液体提取后）的细胞引导至主通道中心。对微通道网络的设计进行了理论和数值分析，以确保在每个连接处保持最小流速比（2.5:1，主通道与侧通道），并预测血浆出口处的流速。收缩部分的尺寸和位置通过数值模拟确定。通过比较有收缩部分和无收缩部分的装置性能，证明了连接处之前存在收缩部分的效果。为了展示该装置的性能，首先使用聚苯乙烯微珠（尺寸为10和15μm）和液滴进行了实验。最后，该装置用于HL60细胞的浓缩以及稀释血样中血浆和细胞的分离。使用血细胞计数器和荧光激活细胞分选仪（FACS）对细胞浓度和血浆-血细胞纯化效率进行了量化。使用HL60细胞获得了7倍的细胞浓缩，对于稀释（1:20）血样，观察到纯化效率为70%，血浆回收率为80%。使用FACS鉴定细胞裂解情况，并使用台盼蓝试验检查细胞活力，结果表明超过99%的细胞存活，这表明该装置适用于实际应用。所提出的装置有潜力用作基于芯片实验室诊断平台的样品制备模块。
