We recently introduced methods to tether phospholipid vesicles or proteoliposomes onto a fluid-supported lipid bilayer using DNA hybridization (Yoshina-Ishii, C.; Miller, G. P.; Kraft, M. L.; Kool, E. T.; Boxer, S. G. J. Am. Chem. Soc. 2005, 127, 1356-1357). These intact tethered vesicles diffuse in two dimensions parallel to the supporting membrane surface. In this article, we report the dynam...

The understanding of electrokinetic transport of fluid or particles in microchannel plays an important role in the design and the optimization of microand nanofluidic devices. Two important electrokinetic phenomena are electro-osmosis and electrophoresis. In order to study these phenomena, the lattice Boltzmann solver is coupled with the iteration solver for the Poisson equation. Using these nu...

We investigate electro-osmosis in aqueous solutions of polyelectrolytes using mean-field equations. A solution of positively charged polyelectrolytes is confined between two negatively charged planar surfaces, and an electric field is applied parallel to the surfaces. When electrostatic attraction between the polymer and the surface is strong, the polymers adhere to the surface, forming a highl...

The net flow of electrolyte induced by an ac electric potential applied to an array of asymmetric pairs of microelectrodes has recently been reported. The interaction between the oscillating electric field and the oscillating induced charge at the diffuse double layer on the electrodes results in a steady electro-osmotic velocity distribution on top of the electrodes. This slip velocity distrib...

We investigate experimentally the electrokinetic properties of soft nanofluidic channels that consist in soap films with nanometric thickness, covered with charged surfactants. Both the electric and fluidic responses of the system are measured under an applied voltage drop along the film. The electric field is shown to induce an electro-osmotic hydrodynamic flow in the film. However, in contras...

The mechanism by which fluid is transported across epithelial layers is still unclear. The prevalent idea is that fluid traverses these layers transcellularly, driven by local osmotic gradients secondary to electrolyte transport and utilizing the high osmotic permeability of aquaporins. However, recent findings that some aquaporin knockout mice epithelia transport fluid sow doubts on local osmo...

Recent numerical and experimental studies have investigated the increase in efficiency of microfluidic ac electro-osmotic pumps by introducing nonplanar geometries with raised steps on the electrodes. In this study, we analyze the effect of the step height on ac electro-osmotic pump performance. AC electro-osmotic pumps with three-dimensional electroplated steps are fabricated on glass substrat...

The differential migration of ions in an applied electric field is the basis for separation of chemical species by capillary electrophoresis. Axial diffusion of the concentration peak limits the separation efficiency. Electromigration dispersion is observed when the concentration of sample ions is comparable to that of the background ions. Under such conditions, the local electrical conductivit...

Dynamic and steady-state water flux, current density, and resistance across a Nafion 115 membrane-electrode-assembly (MEA) were measured as functions of temperature, water activity, and applied potential. After step changes in applied potential, the current, MEA resistance, and water flux evolved to new values over 3000-5000 s, indicating a slow redistribution of water in the membrane. Steady-s...