Fluidic instability is another key limitation to increased volumetric throughput. When the channel cross section becomes large, mixing driven by fluid vortices drastically decreases the efficiency of enrichment and separation. To understand how to mitigate this detrimental process, several research groups have proposed theoretical models describing mechanisms for vortex formation. These models indicate that the dominant mechanism can vary based on the critical dimensions of the microchannel and the concentration of the BGE. Experimental approaches have been developed to limit vortex formation, including geometric restriction of the fluid in microslits, creation of an alternate current path through the IDZ by coating the channel with a highly conductive polymer, and addition of microposts to augment surface conduction within the IDZ. For these reasons, we anticipated that an additional bed of insulating microbeads, positioned within the IDZ would promote fluidic stability (Scheme 1f).