基于非对称电极的定比例颗粒聚集

Induced charge electroosmosis (ICEO) trapping of particles was proposed in 2015, which has attracted broad attention in microfluidic community for its flexibility and ease in integration. By depositing a pair of wide and narrow metal strips (floating electrode) in the bottom of channel, after energizing AC signal on driving electrodes parallel to floating electrode, particle trapping of proportional scale occur above each floating electrode respectively due to the asymmetric ICEO vortexes. The derivation of electrode surface slip velocity in DC limit and numeric simulation of volumetric flow rate were performed to obtain the velocity distribution which indicates that the number of particles trapped is proportional to the width of electrode. Based on the forces analysis of typical particle and the surface-averaged slip velocity under various conditions, an effective slip velocity profile and the corresponding operating range is presented, which is also validated by the experiments. The results provide the theoretical and experimental basis for generating proportional trapping and gradient concentration of particles.