Dielectrophoresis, an electrokinetic technique, can be used for contactless manipulation of micro- and nano-size particles suspended in a fluid. We present a 3-D microfluidic DEP device with an orthogonal electrode configuration that uses negative dielectrophoresis to trap spherical polystyrene micro-particles. Traps with three different basic geometric shapes, i.e. triangular, square, and circular, and a fixed trap area of around 900 μm² were investigated to determine the effect of trap shape on dynamics and strength of particle trapping. Effects of trap geometry were quantitatively investigated by means of trap stiffness, with applied electric potentials from 6 V_P-P to 10 V_P-P at 1 MHz. Analyzing the trap stiffness with a trapped 4.42 μm spherical particle showed that the triangular trap is the strongest, while the square shape trap is the weakest. The trap stiffness grew more than eight times in triangular traps and six times in both square and circular traps when the potential of the applied electric field was increased from 6 V_P-P to 10 V_P-P at 1 MHz. With the maximum applied potential, i.e. 10 V_P-P at 1 MHz, the stiffness of the triangular trap was 60% and 26% stronger than the square and circular trap, respectively. A finite element model of the microfluidic DEP device was developed to numerically compute the DEP force for these trap shapes. The findings from the numerical computation demonstrate good agreement with the experimental analysis. The analysis of three different trap shapes provides important insights to predict trapping location, strength of the trapping zone, and optimized geometry for high throughput particle trapping.

介电泳是一种电动技术，可用于对悬浮在流体中的微米级和纳米级粒子进行非接触式操作。我们提出了一种具有正交电极配置的 3-D 微流体 DEP 设备，该配置使用负介电泳来捕获球形聚苯乙烯微粒。研究了具有三种不同基本几何形状（即三角形、方形和圆形）以及大约 900 μm ²的固定陷阱面积的陷阱，以确定陷阱形状对粒子陷阱的动力学和强度的影响。通过陷阱刚度定量研究陷阱几何形状的影响，施加的电势从 6 V _P-P到 10 V _P-P在 1 兆赫。用被困的 4.42 μm 球形颗粒分析陷阱刚度表明，三角形陷阱最强，而方形陷阱最弱。当外加电场的电位在 1 MHz 下从 6 V _P-P增加到 10 V _P-P时，三角形陷阱的陷阱刚度增加了 8 倍以上，方形和圆形陷阱的陷阱刚度增加了 6 倍。具有最大施加电位，即 10 V _P-P在 1 MHz 时，三角形陷阱的刚度分别比方形和圆形陷阱强 60% 和 26%。开发了微流体 DEP 设备的有限元模型，以数值计算这些陷阱形状的 DEP 力。数值计算的结果与实验分析非常吻合。三种不同陷阱形状的分析为预测陷阱位置、陷阱区域的强度和高通量粒子陷阱的优化几何形状提供了重要的见解。