Insulator-based dielectrophoresis (iDEP) has become a powerful tool for biomicrofluidic separation and analysis because it is capable to selectively separate biological particle systems according to properties like size, material, and shape. However, it has rarely been used to solve challenging separation problems involving nonbiological particles, namely, for systems that are prone to particle agglomeration. Here, we demonstrate material-selective separation of nonbiological systems, i.e., polystyrene and gold-coated polystyrene particles of two different sizes, using iDEP at high accuracy. For this purpose, we present a method to generate fluorescent gold-coated particles. We further introduce a method to reduce the static backpressure that builds up between in- and outlet reservoir due to electroosmotic flow. Moreover, we found that particle agglomeration makes their separation impossible when conventional iDEP routines are applied. Therefore, two solutions to reduce particle agglomeration are presented: A combination of AC and DC potentials and adjustment of pH and conductivity of the suspending medium. Both approaches allow separating particles under challenging conditions such as initially low absolute particle zeta potentials and high particle concentrations. Since those conditions can also be present in biological iDEP separation processes, the results are of general value for biological and nonbiological iDEP operations.

中文翻译：

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通过基于绝缘体的介电电泳对混合微粒进行材料选择性分离。

基于绝缘体的介电电泳（iDEP）已成为用于生物微流体分离和分析的强大工具，因为它能够根据大小，材料和形状等属性选择性地分离生物粒子系统。但是，它很少用于解决涉及非生物颗粒的具有挑战性的分离问题，即用于易于发生颗粒团聚的系统。在这里，我们演示了使用iDEP高精度地对非生物系统进行材料选择性分离，即两种不同尺寸的聚苯乙烯和金包被的聚苯乙烯颗粒。为此，我们提出了一种产生荧光金涂层颗粒的方法。我们进一步介绍了一种减少由于电渗流而在进水口和进水口之间累积的静态背压的方法。此外，我们发现，当应用常规iDEP程序时，粒子的团聚使其无法分离。因此，提出了两种减少颗粒团聚的解决方案：交流和直流电势的组合以及悬浮介质的pH和电导率的调节。两种方法都允许在挑战性条件下分离颗粒，例如最初的低绝对zeta电位和高颗粒浓度。由于这些条件也可能存在于生物iDEP分离过程中，因此该结果对于生物和非生物iDEP操作具有一般价值。交流和直流电势以及悬浮介质的pH和电导率调节的组合。两种方法都允许在挑战性条件下分离颗粒，例如最初的低绝对zeta电位和高颗粒浓度。由于这些条件也可能存在于生物iDEP分离过程中，因此该结果对于生物和非生物iDEP操作具有一般价值。交流和直流电势以及悬浮介质的pH和电导率调节的组合。两种方法都允许在挑战性的条件下分离颗粒，例如最初的低绝对zeta电位和高颗粒浓度。由于这些条件也可能存在于生物iDEP分离过程中，因此该结果对于生物和非生物iDEP操作具有一般价值。