Effect of Solid-Fluid Energy Parameters on Streaming Potential and Flow Rate in Pressure-Driven Flow in Microchannels

Electrokinetic phenomena play an important role in microfluidic transport behavior. Review of literature suggests that surface energetic can also be an important factor, but rarely explored. Typically, surface energetic is taken into account by consideration as an arbitrarily selected slip boundary condition in the modified Navier-Stokes equation. In this paper, instead of selecting this arbitrary slip condition, we examine how solid-liquid energy parameters influence the transport of microfluidics in terms of streaming potential. The simultaneous effects of surface energetics and electrokinetics will be conducted by means of a mean-field free energy lattice boltzmann approach recently proposed. Rather than using the conventional Navier-Stokes equation with a slip condition, the description solid-liquid energetic is manifested by the more physical energy parameters in the mean-field description of the method. As a result, the magnitude of liquid slip can be related directly to the solid-liquid interfacial slip. These results will be employed in conjunction with the description of electrokinetic transport phenomena for streaming potential. The variation of streaming potential as a function of the energy parameters (solid-liquid interaction) is clearly demonstrated. In pressure-driven liquid microfluidics, the flow rate may be decreased due to the counter-effect between the electrokinetic and slip.