Revealing molecular insights into surface charge and local viscosity in electroosmotic flows

Abstract

The limitations of the continuum theory in predicting osmotic response at the nanoscale stem from its lack of molecular-level insight into local fluid properties and the interfacial structure of fluid and electrolyte solutions. To overcome this challenge, our study integrates molecular dynamics (MD) simulation with the continuum framework to explore how surface charge and various hydrodynamic properties impact electroosmotic flow (EOF). The failure of continuum theories to account for molecular interactions and geometric boundaries leads to significant disparities between MD simulations and continuum predictions, influenced by local fluid properties and the electric field. Emphasizing the importance of incorporating appropriate local hydrodynamic properties and atomic interface boundary conditions, our findings bridge the gap between MD simulations and continuum EOF predictions. Our computational results and theoretical model, considering surface charge, atomic interface boundaries, and dynamic structure-based hydrodynamic properties, provide crucial insights and guidance for EOF investigations.