Tuning electroosmotic flow of aqueous electrolytes in nanochannels with implanted wall electrodes

The accurate prediction and precise control over electroosmotic flows at the nanoscale plays a pivotal role for the design and development of integrated micro-nano fluidic systems. In the present work, the electroosmotic flow of aqueous electrolytic solutions confined inside a nanochannel with implanted wall electrodes is thoroughly investigated. In the simulations, each channel wall consists of four layers of atoms in a face-centered cubic (FCC) lattice. The surface atoms of the walls are maintained at a constant charge density and different charging conditions are applied for the implanted electrode atoms. The channels are filled with different monovalent aqueous electrolytes at a desired pressure and an external homogeneous electric field is applied along channel axis. The ion concentration and electrical potential distribution inside the EDL strongly depends on the ion type and the charging condition of the electrodes. The velocity and concentration profiles show striking dissimilarity from previous investigations for homogenously charged surfaces including local flow reversal and modified ion distribution. By tuning the electrode charge, the local electro-kinetic driving force can be altered which can effectively manipulate the local flow direction of the electrolyte.