Improved particle concentration by cascade AC electroosmotic flow
Improved particle concentration by cascade AC electroosmotic flow
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DOI：
10.1007/s10404-012-1109-1
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发表时间：
2013-06-01
影响因子：
2.8
通讯作者：
Honami, Shinji
中科院分区：
文献类型：
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作者：
Motosuke, Masahiro;Yamasaki, Keichi;Honami, Shinji
电动力学在微流控技术中的重要性由于其在制造、实施和处理方面的多功能性和简单性而不断增长。交流电渗（ACEO）是通过交流电场与电极表面双电层的相互作用使离子运动而使流体运动的一种方法，它具有用于检测微通道内流动样品的颗粒浓度方法的潜力。本研究探讨了一种改进的ACEO为基础的颗粒浓度的级联电动方法。通过对ACEO产生的流场和颗粒聚集行为的参数化测量，探讨了ACEO的浓缩机理。通过ACEO的颗粒的积累可以通过用于输送颗粒的衰减电渗流与颗粒的固有扩散运动之间的平衡来解释，所述固有扩散运动由于近壁位置而受到阻碍。尽管平行双间隙电极几何形状使得颗粒能够非常尖锐地收集在电极的中心处，但是其具有在通道的侧壁处具有累积颗粒的散射区。这一缺点可以通过在聚焦区上游应用鞘流或引入级联电极图案来克服。结果，对于在级联装置中流动的所有颗粒，总浓缩效率为98.4%。所得的浓缩颗粒存在于5 μ m内的电极表面上，并且使用单片通道、共面电极和无鞘溶液供给，可以实现具有高达700的浓缩因子的颗粒的三维浓缩。这种级联电动力学方法为稀有样品的超灵敏检测提供了一种新的有效的预富集器。
The importance of electrokinetics in microfluidic technology has been growing owing to its versatility and simplicity in fabrication, implementation, and handling. Alternating-current electroosmosis (ACEO), which is the motion of fluid due to the ion movement by an interaction between AC electric field and an electrical double layer on the electrode surface, has a potential for a particle concentration method to detecti rare samples flowing in a microchannel. This study investigates an improved ACEO-based particle concentration by cascade electrokinetic approach. Flow field induced by ACEO and accumulation behavior of particles were parametrically measured to discuss the concentrating mechanism. The accumulation of particles by ACEO can be explained by a balance between the attenuating electroosmotic flow to transport particles and the inherent diffusive motion of the particles, which is hindered due to the near-wall location. Although a parallel double-gap electrode geometry enables particles to be collected at the center of electrode very sharply, it has scattering zones with accumulated particles at sidewalls of the channel. This drawback can be overcome by applying sheath flow or introducing cascade electrode pattern upstream of the focusing zone. As a result, total concentration efficiency was 98.4 % for all the particles flowing in the cascade device. The resultant concentrated particles exist on the electrode surface within 5 mu m, and three-dimensional concentration of particle with the concentration factor as large as 700 is possible using a monolithic channel, co-planar electrode, and sheathless solution feeding. This cascade electrokinetic method provides a new and effective preconcentrator for ultra-sensitive detection of rare samples.