A low sample volume particle separation device with electrokinetic pumping based on circular travelling-wave electroosmosis
A low sample volume particle separation device with electrokinetic pumping based on circular travelling-wave electroosmosis
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DOI：
10.1039/c3lc50343g
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发表时间：
2013-01-01
期刊：
影响因子：
6.1
通讯作者：
Tung, Yi-Chung
中科院分区：
文献类型：
--
作者：
Lin, Shiang-Chi;Lu, Jau-Ching;Tung, Yi-Chung
颗粒分离是样品制备过程中的关键步骤。小体积样品的制备在临床诊断和化学分析中尤为重要。微流控技术的优点使其成为颗粒分离的潜在候选者。然而，现有的微流控装置需要外部泵浦源和广泛的几何图形才能获得高的分离效率，这在处理小体积样品时是不利的。提出了一种基于循环行波电渗的低压电动泵送低进样量颗粒分离微流控装置。利用数值计算软件对圆形TWEO和介电(DEP)两种电动机制进行了数值模拟。圆形双剪切流在径向产生速度梯度，导致剪应力诱导力将颗粒拖入装置的中心区域。相反，非平行电极会产生负的DEP力，从而将聚苯乙烯微珠推向外围区域；DEP力的大小取决于聚苯乙烯微珠的大小。我们使用不同大小的颗粒来实验证明颗粒分离的概念。实验表明，由于剪应力诱导力的作用，15微米的微珠被拖入中心区域，而1微米的微珠由于较大的负DEP力而向外部移动。结果表明，15微米和1微米微珠的分离纯度分别为94.4%和80.0%。我们还从一个样品中进一步证明了颗粒分离，该样品包含一小部分6微米微珠和1微米微珠，浓度比为1：300。因此，本文开发的创新设备提供了一种很有前途的解决方案，允许在低至50nL的样品体积内进行颗粒分离。
Particle separation is a crucial step in sample preparation processes. The preparation of low volume samples is especially important for clinical diagnosis and chemical analysis. The advantages of microfluidic techniques have lead them to become potential candidates for particle separation. However, existing microfluidic devices require external pumping sources and extensive geometric patterns to attain high separation efficiency, which is disadvantageous when handling low volume samples. This paper presents a low sample volume particle separation microfluidic device with low voltage electrokinetic pumping based on circular travelling-wave electroosmosis (TWEO). Computational numerical software was utilized to simulate two electrokinetic mechanisms: circular TWEO and dielectrophoresis (DEP). The circular TWEO shear flow generates a velocity gradient in the radial direction which causes a shear stress-induced force to drag particles into the center region of the device. In contrast, the non-parallel electrodes induce negative DEP forces which push polystyrene beads towards the peripheral regions; the magnitude of the DEP forces are dependent on the sizes of the polystyrene beads. We used particles of various sizes to experimentally prove the concept of particle separation. Our experiments show that 15 mu m beads are dragged into the center region due to the shear stress-induced force, and 1 mu m beads move towards the outer region because of the large negative DEP force. The results show a separation purity of 94.4% and 80.0% for 15 mu m and 1 mu m beads respectively. We further demonstrated particle isolation from a sample of containing a small proportion of 6 mu m beads mixed with 1 mu m beads at a concentration ratio of 1 : 300. Therefore, the innovative device developed in this paper provides a promising solution to allow particle separation in sample volumes as low as 50 nL.