Deviations of Electroosmotic Fluidic Profile from Electric Double Layer Theory

2006 1st IEEE International Conference on Nano/Micro Engineered and Molecular Systems Pub Date : 2006-01-01 DOI:10.1109/NEMS.2006.334653

Yongqian Li, Liding Wang, Zheng Xu

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引用次数: 1

Abstract

The plug-like fluidic profile is one of most advantages of electroosmotic flow, which influences the reproducibility, sensitivity and separation efficiency of the microfluidic devices. Electroosmotic flow in microchannels with hydraulic diameters of less than 20 microns are investigated experimentally and qualitatively compared with prediction in electric double layer (EDL) theory. Fluidic profiles are obtained using caged-dye based technique with a high degree of resolution near the channel walls. The experimental results indicate the existence of transition zones, which is characterized by a drastic transition in velocity profile as a matching zone between the channel wall and the middle steady flow. The width scale of the transition layer was found to be the same magnitude of hydraulic diameter and much larger than the prediction in EDL theory, which is correlated with the zeta potential and length ratio of Debye length to channel's hydraulic diameter, while the middle profile is influenced by pressure force and the viscidity force. The experiments indicate that the deviations from plug-like velocity profile can be avoided by the reduction of pressure gradient and the channel's dimensional size

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电渗透流体剖面与双电层理论的偏差

微流控器件的重现性、灵敏度和分离效率受到微流控器件的影响，而微流控器件的塞状流控结构是电渗透技术的最大优势之一。对水力直径小于20微米的微通道中的电渗透流动进行了实验和定性研究，并与双电层理论的预测结果进行了比较。流体分布是使用基于笼状染料的技术获得的，在通道壁附近具有高分辨率。实验结果表明，过渡区存在，其特征是作为通道壁面与中间稳定流的匹配区，流速剖面发生剧烈转变。过渡层的宽度尺度与水力直径大小相同，且比EDL理论预测的要大得多，这与zeta势和德拜长度与管道水力直径的长度比有关，而中间剖面受压力力和粘性力的影响。实验结果表明，通过减小压力梯度和减小通道尺寸，可以避免与类塞速度分布的偏差

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2006 1st IEEE International Conference on Nano/Micro Engineered and Molecular Systems

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