Davies Collin D, Crooks Richard M
Department of Chemistry and Texas Materials Institute , The University of Texas at Austin , 105 E. 24th St., Stop A5300 , Austin , Texas , 78712-1224 , USA . Email:
Chem Sci. 2020 May 20;11(21):5547-5558. doi: 10.1039/d0sc01931c. eCollection 2020 Jun 7.
In this article, we report continuous sorting of two microplastics in a trifurcated microfluidic channel using a new method called serial faradaic ion concentration polarization (fICP). fICP is an electrochemical method for forming ion depletion zones and their corresponding locally elevated electric fields in microchannels. By tuning the interplay between the forces of electromigration and convection during a fICP experiment, it is possible to control the flow of charged objects in microfluidic channels. The key findings of this report are threefold. First, fICP at two bipolar electrodes, configured in series and operated with a single power supply, yields two electric field gradients within a single microfluidic channel (, serial fICP). Second, complex flow variations that adversely impact separations during fICP can be mitigated by minimizing convection by electroosmotic flow in favor of pressure-driven flow. Finally, serial fICP within a trifurcated microchannel is able to continuously and quantitatively focus, sort, and separate microplastics. These findings demonstrate that multiple local electric field gradients can be generated within a single microfluidic channel by simply placing metal wires at strategic locations. This approach opens a vast range of new possibilities for implementing membrane-free separations.
在本文中，我们报告了使用一种称为串联法拉第离子浓度极化（fICP）的新方法，在三叉微流体通道中对两种微塑料进行连续分选。fICP是一种在微通道中形成离子耗尽区及其相应局部增强电场的电化学方法。通过在fICP实验过程中调节电迁移力和对流力之间的相互作用，可以控制微流体通道中带电物体的流动。本报告的主要发现有三点。第一，串联配置并由单个电源操作的两个双极电极处的fICP在单个微流体通道内产生两个电场梯度（串联fICP）。第二，通过最小化电渗流引起的对流以利于压力驱动流，可以减轻fICP过程中对分离产生不利影响的复杂流动变化。最后，三叉微通道内的串联fICP能够连续且定量地聚焦、分选和分离微塑料。这些发现表明，通过在关键位置简单放置金属线，就可以在单个微流体通道内产生多个局部电场梯度。这种方法为实现无膜分离开辟了广泛的新可能性。
