We report on electrokinetic manipulation of submicron particles in a device with microfabricated Si electrodes featuring segmented sidewalls acting as tracks guiding particles under hydrodynamic drag. Electrohydrodynamic drag, both AC electroosmosis in low-conductive medium and electrothermal flow in high-conductive medium, gives rise to fluid rolls that deliver particles to tracks where they are held under the influence of dielectrophoretic forces. Particles are being railed along tracks under pressure-driven flow to a downstream junction where tracks act as bridges, keeping particles on course within the main channel causing their post-junction enrichment. This outcome, however, is strongly coupled to electrode sidewall contours as demonstrated here. We also report on particle oscillations under strong AC electroosmosis. Specifically, particles in deionized water can be seen bouncing off tracks or circulating with convective rolls in and out of space beneath tracks at an oscillation frequency and amplitude depending on the activation frequency. These results collectively draw attention to the functional use of electrode sidewall contours for continuous-flow manipulation of particles, which are rarely explored in microfluidics and yet could lead to more effective designs for particle separation and enrichment.

我们报道了在具有微细加工的硅电极的装置中对亚微米粒子的电动控制，该电极具有分段的侧壁，作为在流体动力阻力下引导粒子的轨道。低流体介质中的交流电渗透和高导电介质中的电热流动的电动流体阻力产生了流体辊，该流体辊将颗粒输送到在介电泳力的作用下被保持的轨道。在压力驱动的流动下，颗粒沿着轨道被导向下游的交汇处，在该处，轨道充当桥梁，将颗粒保持在主通道内的路线上，从而导致它们的结后富集。但是，此结果与此处所示的电极侧壁轮廓紧密相关。我们还报告了强交流电渗透作用下的颗粒振荡。具体来说，可以看到去离子水中的颗粒从轨道上弹起或用对流辊在轨道下方的空间中进出空间，其振荡频率和幅度取决于激活频率。这些结果共同引起了人们对电极侧壁轮廓在连续流操纵颗粒中的功能性使用的关注，这在微流体学中很少探索，但是可能导致更有效的颗粒分离和富集设计。