Power generation cell driven by osmotic pressure in microchannels with hydrophobic surfaces and viscoelectric effects

Abstract

A theoretical study that explores power generation via streaming potential and osmotic gradients is proposed. The system is compounded by an osmotic membrane that has different saline concentrations on each side. This concentration gradient promotes a volumetric flux rate inside a microchannel with parallel plates whose surfaces are made of modified hydrophobic fumed silica, thus, the no-slip condition is no longer sustained. Aside from these characteristics, we consider viscoelectric effects in the analysis. The set of equations is written in dimensionless variables, which are solved with integrodifferential methods, permitting us to obtain semi-analytical solutions for velocity, pressure fields, and the most important: the electric potential generated for the system. This setup converts concentration gradients into electric energy in the form of streaming potential. Besides, we demonstrate that hydrophobic surfaces promote a greater induced streaming potential, nonetheless, for high potentials appears a saturation phenomenon which avoids the growth of the induced electric potential no matter how large the slip-conditions could be.