Amplified electrokinetic response by concentration polarization near nanofluidic channel.
Amplified electrokinetic response by concentration polarization near nanofluidic channel.
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DOI：
10.1021/la900332v
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发表时间：
2009-07-07
期刊：
影响因子：
--
通讯作者：
Han J
中科院分区：
文献类型：
--
作者：
Kim SJ;Li LD;Han J
离子浓差极化是发生在离子选择性膜附近的基本输运现象，但由于理论和实验的挑战，人们对这种重要的膜现象知之甚少。在这里，我们报告了对耗尽区内部和附近的详细流量和电势分布的首次直接测量。这项工作是全面表征耦合传输问题的重要一步。使用与微流体装置集成的微加工电极，我们测量并证实，由于沿微通道的离子浓度分布高度不均匀，离子耗尽区内部的电场比耗尽区外部放大了30倍以上。结果，流体（电渗）和颗粒（电泳）的电动运动显着放大。还首次通过光学跟踪光漂白的中性染料分子测量了耗尽区内的详细流动剖面。我们进一步表明，该设备中产生的放大电动流可用作场控微流体泵和开关。
Ion concentration polarization is the fundamental transport phenomenon that occurs near ion-selective membranes, but this important membrane phenomenon has been poorly understood due to theoretical and experimental challenges. Here, we report the first direct measurements of detailed flow and electric potential profiles within and near the depletion region. This work is an important step towards a full characterization of this coupled transport problem. Using microfabricated electrodes integrated with the microfluidic device, we measured and confirmed that the electric field inside an ion depletion region is amplified more than 30 fold compared to outside of the depletion zone due to the highly non-uniform ion concentration distribution along the microchannel. As a result, the electrokinetic motion of both fluid (electroosmosis) and particle (electrophoresis) was significantly amplified. The detailed flow profile within the depletion zone was also measured for the first time by optically tracking photobleached neutral dye molecules. We further showed that the amplified electrokinetic flows generated in this device may be used as a field-controlled, microfluidic fluid pump and switch.
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