Investigations of Redox Magnetohydrodynamic Fluid Flow At Microelectrode Arrays Using Microbeads
Investigations of Redox Magnetohydrodynamic Fluid Flow At Microelectrode Arrays Using Microbeads
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DOI：
10.1021/ac9020177
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发表时间：
2010-04-01
影响因子：
7.4
通讯作者：
Fritsch, Ingrid
中科院分区：
文献类型：
--
作者：
Anderson, Emily C.;Weston, Melissa C.;Fritsch, Ingrid
微珠用于跟踪微带电极阵列上的流体流动，以研究受限溶液中氧化还原磁流体动力学（redox- mhd）的基本原理。研究结果可为基于氧化还原- mhd概念的微流体全量分析系统的设计提供指导。离子通量是通过在阵列中选定的可单独寻址的微电极上还原和氧化电活性铁和亚铁氰化物钾来产生的。外部磁场是由一个小的永久磁铁（0.38 T）产生的，它的磁场垂直于阵列的平面。离子通量和磁场的叉乘产生磁力（洛伦兹力方程的一部分），使流体围绕活动电极旋转。这里展示了高达1.4毫米/秒的速度。研究了不同氧化还原物质浓度、电极宽度、电极间隙以及阳极极化和阴极极化电极组合对速度的影响。微珠可以绘制与阵列芯片平行或垂直的流动模式和速度。讨论了反剪力、沿壁阻力和加强流的影响。一个重要的结果是，在反向偏置的电极之间获得了横跨650 μ m的相当平坦的流动剖面。
Microbeads are used to track fluid flow over microband electrode arrays to investigate fundamentals of redox magnetohydrodynamics (redox-MHD) in a confined solution. The results may lead toward the design of micro total analysis systems with microfluidics based on the redox-MHD concept. Ion flux was generated by reduction and oxidation of electroactive potassium ferri- and ferrocyanide at selected individually addressable microelectrodes in the array. An external magnetic field was produced by a small, permanent magnet (0.38 T) placed directly below the array with its field perpendicular to the plane of the array. The cross product of ion flux and magnetic field produces a magnetic force (a portion of the Lorentz force equation) that causes the fluid to rotate around the active electrodes. Velocities up to 1.4 mm/s are demonstrated here. The effects on velocities were obtained for different concentrations of redox species, widths of electrodes, gaps between electrodes, and combinations of anodically- and cathodically polarized electrodes. The microbeads allowed mapping of flow patterns and velocities, both parallel and perpendicular to the array chip. The influence of counteracting shear forces, drag along the walls, and reinforcing flow are discussed. A significant result is the fairly flat flow profile across 650 mu m, attained between electrodes that are oppositely biased.