Fernández-Mateo Raúl, García-Sánchez Pablo, Ramos Antonio, Morgan Hywel
School of Electronics and Computer Science, University of Southampton, Southampton SO17 1BJ, UK.
Depto. Electrónica y Electromagnetismo, Facultad de Física, Universidad de Sevilla, Avda. Reina Mercedes s/n, 41012, Sevilla, Spain.
Lab Chip. 2024 May 28;24(11):2968-2974. doi: 10.1039/d4lc00081a.
Concentration-polarization electroosmosis (CPEO) refers to steady-state electroosmotic flows around charged dielectric micro-particles induced by low-frequency AC electric fields. Recently, these flows were shown to cause repulsion of colloidal particles from the wall of a microfluidic channel when an electric field is applied along the length of the channel. In this work, we exploit this mechanism to demonstrate fractionation of micron-sized polystyrene particles and bacteria in a flow-focusing device. The results are in agreement with predictions of the CPEO theory. The ease of implementation of CPEO-based fractionation in microfluidics makes it an ideal candidate for combining with current techniques commonly used to generate particle lift, such as inertial or viscoelastic focusing, requiring no extra fabrication steps other than inserting two electrodes.
浓度极化电渗（CPEO）是指由低频交流电场引起的围绕带电介电微粒的稳态电渗流。最近研究表明，当沿微流控通道长度方向施加电场时，这些流动会导致胶体颗粒从微流控通道壁排斥。在这项工作中，我们利用这一机制在流动聚焦装置中实现微米级聚苯乙烯颗粒和细菌的分离。结果与CPEO理论的预测一致。基于CPEO的分离在微流控中易于实现，这使其成为与当前常用于产生颗粒升力的技术（如惯性或粘弹性聚焦）相结合的理想候选方法，除了插入两个电极外无需额外的制造步骤。
