Thwar Prasanna K, Linderman Jennifer J, Burns Mark A
Department of Chemical Engineering, University of Michigan, Ann Arbor, MI, USA.
Electrophoresis. 2007 Dec;28(24):4572-81. doi: 10.1002/elps.200700373.
We demonstrate dielectrophoretic (DEP) potential wells using pairs of insulating oil menisci to shape the DC electric field. These oil menisci are arranged in a configuration similar to the quadrupolar electrodes, typically used in DEP, and are shown to produce similar field gradients. While the one-pair well produces a focusing effect on particles in flow, the two-pair well results in creating spatial traps against crossflows. Uncharged polystyrene particles were used to map the DEP force fields and the experimental observations were compared against the field profiles obtained by numerically solving Maxwell's equations. We demonstrate trapping of a single particle due to negative DEP against a pressure-driven crossflow. This can be easily extended to trap and hold cells and other objects against flow for a longer time. We also show the results of particle trapping experiments performed to observe the effect of adjusting the oil menisci and the gap between two pairs of menisci in a four-menisci configuration on the nature of the DEP well formed at the center. A design parameter, Theta, capturing the dimensions of the DEP energy well, is defined and simulations exploring the effects of different geometric features on Theta are presented.
我们利用成对的绝缘油弯月面来塑造直流电场，展示了介电泳（DEP）势阱。这些油弯月面的排列方式类似于DEP中常用的四极电极，并显示出能产生相似的场梯度。虽然单对势阱对流动中的粒子产生聚焦作用，但两对势阱则能形成抵抗横向流的空间陷阱。使用不带电的聚苯乙烯粒子来绘制DEP力场，并将实验观察结果与通过数值求解麦克斯韦方程组获得的场分布进行比较。我们展示了由于负介电泳而使单个粒子在压力驱动的横向流中被捕获的情况。这可以很容易地扩展到长时间捕获和固定细胞及其他物体以抵抗流动。我们还展示了粒子捕获实验的结果，该实验旨在观察在四弯月面配置中调整油弯月面以及两对弯月面之间的间隙对在中心形成的DEP阱性质的影响。定义了一个捕获DEP能量阱尺寸的设计参数Theta，并给出了探索不同几何特征对Theta影响的模拟结果。
