An open-tubular radially cyclical electric field-flow fractionation technique which achieves the online separation of microparticles in a functional annular channel is proposed in this study. The system was set up by using a stainless steel tube and a platinum wire modified with ionic liquid/mesoporous silica materials as the external and internal electrodes. The feasibility for online separation of various particles was experimentally demonstrated. Particles in the channel were affected by a radial electric field and field-flow fractionation (FFF). On the cross section, different particles showed distinctive migration distances depending on their own properties and the different magnitudes of forces being exerted. The same kind of particles form an annular distribution within the same annulus while different particles form annular distributions at varied concentric annuli through electrophoresis. Under a laminar flow of FFF, different sizes of particles formed a conical arrangement within the annular separation channel. With the joint influence of electric field and flow field, different trajectories were obtained and the particles were eventually separated. Voltage, frequency and duty cycle value are the main parameters affecting the separation of particles. By adjusting these parameters, particles migrate in a zigzag trajectory on one side of the electrodes (mode I) and reach both sides of the electrodes (mode II). Six polystyrene particles were completely separated with high resolution within several minutes. Our system offers numerous advantages of label-free, high-resolution and online separation without tedious operations, and it is a promising tool for the effective separation of various micro-objects.

中文翻译：

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开管径向循环电场流分馏（OTR-CyElFFF）：一种用于同时分离微粒的在线同心分布策略。

这项研究提出了一种开放管状径向循环电场流分馏技术，该技术可实现功能性环形通道中微粒的在线分离。通过使用不锈钢管和用离子液体/介孔二氧化硅材料改性的铂丝作为外部和内部电极来建立系统。实验证明了在线分离各种颗粒的可行性。通道中的粒子受到径向电场和场流分级分离（FFF）的影响。在横截面上，不同的粒子显示出不同的迁移距离，这取决于其自身的性质以及所施加的力的大小。相同种类的粒子在同一环空内形成环形分布，而不同的粒子通过电泳在变化的同心环空处形成环形分布。在FFF的层流作用下，不同大小的颗粒在环形分离通道内形成圆锥形排列。在电场和流场的共同影响下，获得了不同的轨迹，最终使颗粒分离。电压，频率和占空比值是影响颗粒分离的主要参数。通过调整这些参数，粒子以锯齿形轨迹在电极的一侧（模式I）迁移并到达电极的两侧（模式II）。数分钟内以高分辨率将六个聚苯乙烯颗粒完全分离。