Electrophoresis of concentrated suspension of soft particles with volumetrically charged inner core

The present study deals with the electrophoresis of a concentrated suspension of soft particles. The inner core of the undertaken particles is considered to possess constant volumetric charges and is surrounded by an ion- and fluid-penetrable polyelectrolyte layer (PEL) with uniformly distributed immobile charges. Such types of particles are paradigm of several bio-particles, for example, virus, bacteria, yeasts, and humic substances, to name a few. A unit cell model is employed to take into account the effect of the interaction between neighboring particles. In the present study, we restrict ourselves with the low charge density and weak applied electric field assumptions. The electric potential distribution is obtained from the linearized Poisson-Boltzmann equation. The fluid velocity field inside the PEL and portion of the cell filled with electrolyte solution are determined by solving the Darcy-Brinkman and Stokes equations, respectively. We provide semi-analytical results for the mean electrophoretic mobility of the concentrated suspension of the undertaken soft particles. We have shown extensively that the suspension of the soft particles may switch its propulsion direction depending on the choice of the pertinent parameters. Unlike suspension of bare colloids or full porous particles, the mean electrophoretic mobility of the soft particles may be nonzero even at a net zero charge case.