Automated electric valve for electrokinetic separation in a networked microfluidic chip
Automated electric valve for electrokinetic separation in a networked microfluidic chip
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DOI：
10.1021/ac061845h
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发表时间：
2007-02-15
影响因子：
7.4
通讯作者：
Ivory, Cornelius F.
中科院分区：
文献类型：
--
作者：
Cui, Huanchun;Huang, Zheng;Ivory, Cornelius F.
本文描述了一种自动电动阀系统，旨在减少分散和样品损失到侧通道时，电动动员的浓度区通过网络微流控芯片中的T型接头。减少分散的一种方法是控制电流流线，因为带电物质在没有电渗流的情况下被沿着它们驱动。计算机模拟表明，分散和样品损失可以通过在侧通道中施加恒定的附加电场来拉直线性电动流动（区带电泳）中的电流流线来减少。这种额外的电场是由一对铂微电极提供的，该电极集成到芯片的T型结附近。模拟和实验均表明，这种具有恒定阀电压的电动阀在非线性电泳（等速电泳）期间的阀性能不令人满意。然而，在这些结果的基础上，开发了具有改进的阀性能的自动电动阀系统。用该系统进行的实验表明，随着蛋白质区等速通过T-接头，分散性降低，再现性增加。自动电动阀的模拟提供了进一步的支持，所需的形状的电流流线保持在T型接头在等速电泳。基于分散引起的统计方差，在不同阀电流下评价阀性能。通过自动控制系统，两个集成的微电极提供了一种有效的方式来操纵电流流线，从而在电动分离中充当带电物种的电动阀。
This paper describes an automated electric valve system designed to reduce dispersion and sample loss into a side channel when an electrokinetically mobilized concentration zone passes a T-junction in a networked microfluidic chip. One way to reduce dispersion is to control current streamlines since charged species are driven along them in the absence of electroosmotic flow. Computer simulations demonstrate that dispersion and sample loss can be reduced by applying a constant additional electric field in the side channel to straighten current streamlines in linear electrokinetic flow (zone electrophoresis). This additional electric field was provided by a pair of platinum microelectrodes integrated into the chip in the vicinity of the T-junction. Both simulations and experiments of this electric valve with constant valve voltages were shown to provide unsatisfactory valve performance during nonlinear electrophoresis (isotachophoresis). On the basis of these results, however, an automated electric valve system was developed with improved valve performance. Experiments conducted with this system showed decreased dispersion and increased reproducibility as protein zones isotachophoretically passed the T-junction. Simulations of the automated electric valve offer further support that the desired shape of current streamlines was maintained at the T-junction during isotachophoresis. Valve performance was evaluated at different valve currents based on statistical variance due to dispersion. With the automated control system, two integrated microelectrodes provide an effective way to manipulate current streamlines, thus acting as an electric valve for charged species in electrokinetic separations.