Manipulation and characterization of red blood cells with alternating current fields in microdevices
Manipulation and characterization of red blood cells with alternating current fields in microdevices
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DOI：
10.1002/elps.200305644
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发表时间：
2003-11-01
期刊：
影响因子：
2.9
通讯作者：
Chang, HC
中科院分区：
文献类型：
--
作者：
Minerick, AR;Zhou, RH;Chang, HC
研究了微流控装置中红细胞悬浮液在高频交变电场作用下的运动，采用平行和正交电极结构来描述各种基本驱动力。在现场应用的最初几秒钟内，观察到由于电极极化与细胞膜极化相互作用而引起的细胞对铂电极的斥力是作用在粒子上的最大力。我们利用这种强烈的排斥力将生物颗粒集中在微电极之间，以放大微流控器件中一个小而特征良好的区域中的多粒子聚集现象和介电泳动(DEP)操作。二次运动包括由于粒子极化而沿场线形成RBC珍珠链，然后是经典的跨场线到弱场区域的介电运动。它们是由比最初的电极斥力弱得多的偶极-偶极和场-偶极相互作用驱动的。在不同的交流频率下，RBC链长和聚集的细胞总数被呈现出来，并且被电极斥力显著放大。粒子离开极化电极的运动被发现是对物种和年龄敏感的，并且可以单独作为一种有前途的识别和分离机制。在0.1 S/m等渗磷酸盐缓冲溶液中，在约1 MHz的最佳频率下观察到最大的细胞迁移率，对应于细胞双层和电极极化层的反向扩散时间。这表明，在低MHz频率范围内，颗粒和电极的介电响应主要是由离子从块体到其界面的正常电迁移决定的。对红细胞年龄和物种的敏感性表明，表面蛋白和膜离子通道可以影响界面的电容，以容纳来自本体的离子。这种表面离子积累和极化机制不同于经典的介电理论。在约1 MHz处，电极极化的共振频率落在正、负介电共振峰之间，这表明双层极化机制是一种独特且潜在重要的生物制品操纵工具。
The motion of a suspension of erythrocytes (red blood cells, RBCs) in response to a high-frequency alternating current (AC) field in a microfluidic device is examined with parallel and orthogonal electrode configurations to delineate the various fundamental driving forces. Cell repulsion from the platinum electrodes due to electrode polarization interacting with cell membrane polarizations is observed to be the strongest force acting on the particles in the first few seconds of field application. We exploit this strong repulsion to concentrate the bioparticles between the microelectrodes to amplify multiparticle aggregation phenomenon and dielectrophoretic (DEP) manipulation in a small and well-characterized region within the microfluidic device. Secondary motions include RBC pearl chain formation along field lines due to particle polarization followed by classical dielectrophoretic motion of the chains across field lines to regions of weaker field. These are driven by far weaker dipole-dipole and field-dipole interactions than the preliminary electrode repulsions. RBC chain length and total aggregated cells are presented for a variety of AC frequencies and are significantly amplified by the electrode repulsion. Motion of particles away from the polarized electrode is found to be species- and age-sensitive and can stand by itself as a promising identification and separation mechanism. In a 0.1 S/m isotonic phosphate buffer saline medium, we observe the largest cell mobilities at an optimal frequency of approximately 1 MHz, corresponding to the inverse diffusion time across the double layer of the cell and across the electrode's polarized layer. This suggests that the dielectric responses of both particles and electrodes in the low MHz frequency range are mostly determined by normal electromigration of ions from the bulk to their interfaces. Sensitivity to RBC age and species suggests that the surface proteins and membrane ion channels can affect the capacitance of the interface to accommodate the ions from the bulk. Such surface ion accumulation and polarization mechanisms are different from the classical dielectric theories. The resonant frequency of electrode polarization at around 1 MHz falls between positive and negative dielectrophoretic resonant frequency peaks suggesting that the double-layer polarization mechanism is a distinct and potentially important bioparticle manipulation tool.