Effect of ionic diffusion on microscale electrohydrodynamic conduction pumps

In this work, we investigate microscale electrohydrodynamic (EHD) conduction pumps of dielectric liquids in a wide working regime range from the Ohmic to saturation regime. We show that electric force EHD differs macroscale owing scale effect. reveal effect is triggered by enhanced ionic diffusion. When characteristic length system reduces millimeter micrometer, maximum order magnitude α increases O(10−5) O(10−1), resulting significantly diffusion; however, diffusion can be neglected for pumps, where denotes ratio velocity migration velocity. found existing theoretical models do not work due rough estimation heterocharge layer thickness. thickness only depends on but also relies By modifying expression with respect and diffusion, develop model dimensionless pumps.