There is a growing interest in the advancement of microscale electrokinetic (EK) systems for biomedical and clinical applications, as these systems offer attractive characteristics such as portability, robustness, low sample requirements and short response time. The present work is focused on manipulating the characteristics of the insulating post arrangement in insulator-based EK (iEK) systems for separating a binary mixture of spherical microparticles with same diameter (5.1 μm), same shape, made from the same substrate material and only differing in their zeta potential by ∼14 mV. This study presents a combination of mathematical modeling and experimental separations performed by applying a low-frequency alternating current (AC) voltage in iEK systems with 12 distinct post arrangements. These iEK devices were used to systematically study the effect of three spatial characteristics of the insulating post array on particle separations: the horizontal separation and the vertical separation between posts, and introducing an offset to the posts arrangement. Through normalization of the spatial separation between the insulating posts with respect to particle diameter, guidelines to improve separation resolution for different particle mixtures possessing similar characteristics were successfully identified. The results indicated that by carefully designing the spatial arrangement of the post array, separation resolution values in the range of 1.4–2.8 can be obtained, illustrating the importance and effect of the arrangement of insulating posts on improving particle separations. This study demonstrates that iEK devices, with effectively designed spatial arrangement of the insulating post arrays, have the capabilities to perform discriminatory separations of microparticles of similar characteristics.

中文翻译：

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操纵直流偏置 AC-iEK 设备中的绝缘柱排列以改善微粒分离

人们对生物医学和临床应用的微型动电 (EK) 系统的发展越来越感兴趣，因为这些系统具有便携性、稳健性、样品需求量低和响应时间短等有吸引力的特性。目前的工作重点是操纵基于绝缘体的 EK (iEK) 系统中绝缘柱排列的特性，用于分离具有相同直径 (5.1 μm)、相同形状、由相同基材材料制成且仅由球形微粒组成的二元混合物它们的 zeta 电位相差约 14 mV。这项研究提出了数学建模和实验分离的结合，通过在具有 12 个不同柱排列的 iEK 系统中应用低频交流 (AC) 电压来执行。这些 iEK 设备用于系统地研究绝缘柱阵列的三个空间特性对颗粒分离的影响：柱之间的水平分离和垂直分离，并引入柱排列的偏移。通过根据粒径对绝缘柱之间的空间分离进行标准化，成功地确定了提高具有相似特性的不同颗粒混合物的分离分辨率的指南。结果表明，通过仔细设计绝缘柱阵列的空间排列，可以获得1.4~2.8范围内的分离分辨率值，说明了绝缘柱排列对改善颗粒分离的重要性和效果。这项研究表明，iEK 设备通过有效设计绝缘柱阵列的空间排列，能够对具有相似特性的微粒进行区分分离。