Dielectrophoresis (DEP) has emerged as a viable means of fabricating functional materials and devices via self-assembly of colloidal particles, and has attracted much attention. Despite the extensive studies, how the crossover frequency of a pearl chain changes with the number of forming spheres is still unclear. Here we investigate the crossover frequency of individual two-sphere particles using the optical-tweezer-based phase-shift method and the volumetric polarization and integration (VPI) model. The phase shift method, based on reversal of particle oscillating movement, is capable of measuring the crossover frequency of individual particles with high accuracy; the VPI model considers the electric field distortion due to the particles and the electric double layer. We find that a two-sphere particle possesses a lower crossover frequency than the single sphere due to the competing effect of volume and surface area. Also, there exists an intriguing relationship between the crossover frequency of an n-sphere chain and that of its composing single sphere as follows: f_n-sphere = n^―0.095 f_single. This relationship is independent of the sphere size, medium conductivity, and functional group. Our results provide a rational framework for understanding the DEP behavior of pearl chains and may be useful for future applications using DEP self-assembly technology.

介电电泳（DEP）已经成为通过胶体颗粒的自组装制造功能性材料和器件的可行手段，并引起了广泛的关注。尽管进行了广泛的研究，但珍珠链的交叉频率如何随着形成球的数量变化仍然不清楚。在这里，我们使用基于光镊的相移方法和体积极化与积分（VPI）模型研究单个两球粒子的交叉频率。基于粒子振动运动的反转的相移方法能够高精度地测量单个粒子的交叉频率。VPI模型考虑了由于粒子和双电层引起的电场畸变。我们发现，由于体积和表面积的竞争效应，两球粒子具有比单球更低的穿越频率。同样，在一个扬声器的交叉频率之间存在一个有趣的关系。n球及其组成的单球的链如下：f _n球= n ^-0.095 f _single。这种关系与球的大小，中等电导率和官能团无关。我们的结果为理解珍珠链的DEP行为提供了一个合理的框架，并且可能对使用DEP自组装技术的未来应用有用。