In this work, we aim to observe and study the physics of bacteria and cancer cells pearl chain formation under dielectrophoresis (DEP). Experimentally, we visualized the formation of Bacillus subtilis bacterial pearl chain and human breast cancer cell (MCF‐7) chain under positive and negative dielectrophoretic force, respectively. Through a simple simulation with creeping flow, AC/DC electric fields, and particle tracing modules in COMSOL, we examined the mechanism by which bacteria self‐organize into a pearl chain across the gap between two electrodes via DEP. Our simulation results reveal that the region of greatest positive DEP force shifts from the electrode edge to the leading edge of the pearl chain, thus guiding the trajectories of free‐flowing particles toward the leading edge via positive DEP. Our findings additionally highlight the mechanism why the free‐flowing particles are more likely to join the existing pearl chain rather than starting a new pearl chain. This phenomenon is primarily due to the increase in magnitude of electric field gradient, and hence DEP force exerted, with the shortening gap between the pearl chain leading edge and the adjacent electrode. The findings shed light on the observed behavior of preferential pearl chain formation across electrode gaps.

中文翻译：

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介电泳下的细菌和癌细胞珍珠链

在这项工作中，我们旨在观察和研究介电泳（DEP）下细菌和癌细胞珍珠链形成的物理过程。通过实验，我们观察到枯草芽孢杆菌的形成分别在正负介电泳力作用下的细菌珍珠链和人乳腺癌细胞 (MCF-7) 链。通过在 COMSOL 中使用蠕动流、AC/DC 电场和粒子追踪模块进行简单模拟，我们研究了细菌通过 DEP 在两个电极之间的间隙自组织成珍珠链的机制。我们的模拟结果表明，最大正 DEP 力的区域从电极边缘转移到珍珠链的前缘，从而通过正 DEP 引导自由流动粒子的轨迹朝向前缘。我们的研究结果还强调了为什么自由流动的颗粒更有可能加入现有的珍珠链而不是开始新的珍珠链的机制。这种现象主要是由于电场梯度的大小增加，因此施加了 DEP 力，珍珠链前缘和相邻电极之间的间隙缩短。这些发现揭示了在电极间隙中观察到的优先珍珠链形成行为。