Manipulating fluid flow on a chip through controlled-current redox magnetohydrodynamics
Manipulating fluid flow on a chip through controlled-current redox magnetohydrodynamics
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DOI：
10.1016/j.snb.2012.07.006
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发表时间：
2012-10-01
影响因子：
8.4
通讯作者：
Fritsch, Ingrid
中科院分区：
文献类型：
--
作者：
Weston, Melissa C.;Fritsch, Ingrid
在微电极上使用受控的电子电流以在溶液中产生离子电流，允许用氧化还原-磁流体动力学（氧化还原-MHD）在小规模上进行精确和定量的流体操纵。在溶液中给定时间和位置的MHD力F-B（x，y，z，t）等于离子电流密度j（x，y，z，t）和磁通量密度（或磁感应强度）B（x，y，z，t）的叉积。通过实验在这些参数和实验条件（即流体速度v（x，y，z，t）和通过电极的电流i（t））之间建立定量关系，提供了一种实用的手段，通过该手段以高精度预测和控制小规模的流体流动。对于我们的设置，数据显示，对于固定的B（x，y，z，t），v（x，y，z，t）和i（t）之间的关系是线性的，这表明直接向电极施加电流而不是施加电势的通常方法应该提供微流体的微调，并且以其他常见微泵送方法不可能的水平和简单性。当施加电势时，所产生的电子电流以及因此的离子电流将随着时间以及从一个实验到下一个实验而波动，这是因为不太可控的因素：电子转移动力学、质量转移（例如，来自MHD本身的对流的变化）、浓度（例如，氧化还原物质的耗尽）和电极的结垢。比较了氧化还原磁流体动力学所产生的流体流动与外加电流和外加电位的关系。数据还表明，垂直条v（x，y，z，t）垂直条与垂直条B（x，y，z，t）垂直条之间的关系是线性的。此外，细胞的几何形状对速度的影响进行了研究。这些研究涉及显微镜可视化跟踪微珠，以监测在永磁体存在下的微带阵列上含有电活性亚铁氰化钾和亚铁氰化钾的小体积溶液中的流体速度。此外，三种不同珠类型（6 μ m硫酸盐、10 μ m硫酸盐和6 μ m氨基官能化）的总体流动曲线相似。(C)2012 Elsevier B. V.保留所有权利。
The use of controlled electronic current at microelectrodes to generate ionic current in solution allows precise and quantitative fluid manipulation on a small scale with redox-magnetohydrodynamics (redox-MHD). The MHD force, F-B(x, y, z, t), at a given time and location in solution equals the cross product of the ionic current density, j(x, y, z, t), and magnetic flux density (or magnetic induction), B(x, y, z, t), there. A quantitative relationship is experimentally established between these parameters and experimental conditions, namely the fluid velocity, v(x,y,z,t), and electronic current passing through the electrodes, i(t), providing a practical means by which to predict and control fluid flow on a small scale with great precision. The data show for our setup that the relationship between v(x, y, z, t) and i(t) is linear for a fixed B(x, y, z, t), suggesting that applying current directly to the electrodes, instead of the usual approach of applying a potential, should offer fine tuning of microfluidics and at a level and with simplicity that is not possible with other common micropumping methods. When a potential is applied, the resulting electronic current, and therefore ionic current, will fluctuate in time and from one experiment to the next because of less controllable factors: electron transfer kinetics, mass transfer (e.g. changes in convection from MHD itself), concentration (e.g. depletion of redox species) and fouling of the electrode. A comparison is made between fluid flow generated by redox-MHD using applied electronic current and applied potential. The data also show that the relationship between vertical bar v(x, y, z, t)vertical bar and vertical bar B(x, y, z, t)vertical bar is linear. In addition, effects of cell geometries on velocities were investigated. The studies involved microscope visualization to track microbeads to monitor fluid velocity in a small volume of solution containing electroactive potassium ferri- and ferrocyanide at microband arrays in the presence of permanent magnets. Also, overall flow profiles were similar for three different bead types (6-mu m sulfate, 10-mu m sulfate, and 6-mu m amino-functionalized). (C) 2012 Elsevier B.V. All rights reserved.