Electrokinetic molecular separation in nanoscale fluidic channels
Electrokinetic molecular separation in nanoscale fluidic channels
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DOI：
10.1039/b503914b
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发表时间：
2005-01-01
期刊：
影响因子：
6.1
通讯作者：
López, GP
中科院分区：
文献类型：
--
作者：
Garcia, AL;Ista, LK;López, GP
这份报告提出了一个电动运输的研究，在一系列集成的宏观到纳米流控芯片，允许控制注射到高密度阵列的纳米通道的分子混合物。高纵横比的纳米通道上制作的硅晶片使用干涉光刻和标准的半导体工业过程中，并与透明的派热克斯盖玻片，以允许实验观察。共聚焦激光扫描显微镜被用来检查带负电荷的染料（Alexa 488）和中性染料（罗丹明B）内的纳米通道，从35到200 nm的宽度变化与电场强度等于或低于2000 V m（-1）的电动运输。在带负电荷的通道中，相应溶质和通道壁之间的纳米限制和相互作用引起带负电荷的染料比中性染料朝向负电极的电渗速度更高，导致在相对短的距离（1 mm）上发生的异常分离。增加通道宽度导致在微尺度通道中观察到的电渗传输行为的切换，其中中性分子移动得更快，因为带负电荷的分子被电泳阻力减慢。因此，建立了"纳米“和“微流体”机制之间的明确区别。我们提出了一个分析模型，占电动运输和吸附（中性染料）在通道壁，并与实验数据吻合良好。观察到的效果有可能用于新的纳米分离技术。
This report presents a study of electrokinetic transport in a series of integrated macro- to nanofluidic chips that allow for controlled injection of molecular mixtures into high-density arrays of nanochannels. The high-aspect-ratio nanochannels were fabricated on a Si wafer using interferometric lithography and standard semiconductor industry processes, and are capped with a transparent Pyrex cover slip to allow for experimental observations. Confocal laser scanning microscopy was used to examine the electrokinetic transport of a negatively charged dye ( Alexa 488) and a neutral dye ( rhodamine B) within nanochannels that varied in width from 35 to 200 nm with electric field strengths equal to or below 2000 V m(-1). In the negatively charged channels, nanoconfinement and interactions between the respective solutes and channel walls give rise to higher electroosmotic velocities for the negatively charged dye than for the neutral dye, towards the negative electrode, resulting in an anomalous separation that occurs over a relatively short distance (, 1 mm). Increasing the channel widths leads to a switch in the electroosmotic transport behavior observed in microscale channels, where neutral molecules move faster because the negatively charged molecules are slowed by the electrophoretic drag. Thus a clear distinction between ``nano-'' and "microfluidic'' regimes is established. We present an analytical model that accounts for the electrokinetic transport and adsorption ( of the neutral dye) at the channel walls, and is in good agreement with the experimental data. The observed effects have potential for use in new nano-separation technologies.