Moving charged particles in lattice Boltzmann-based electrokinetics.

The motion of ionic solutes and charged particles under the influence of an electric field and the ensuing hydrodynamic flow of the underlying solvent is ubiquitous in aqueous colloidal suspensions. The physics of such systems is described by a coupled set of differential equations, along with boundary conditions, collectively referred to as the electrokinetic equations. Capuani et al.

Microfluidic pumping by micromolar salt concentrations.

An ion-exchange-resin-based microfluidic pump is introduced that utilizes trace amounts of ions to generate fluid flows. We show experimentally that our pump operates in almost deionized water for periods exceeding 24 h and induces fluid flows of μm s over hundreds of μm. This flow displays a far-field, power-law decay which is characteristic of two-dimensional (2D) flow when the system is strongly confined and of three-dimensional (3D) flow when it is not.

Selective Trapping of DNA Using Glass Microcapillaries.

We show experimentally that an inexpensive glass microcapillary can accumulate λ-phage DNA at its tip and deliver the DNA into the capillary using a combination of electro-osmotic flow, pressure-driven flow, and electrophoresis. We develop an efficient simulation model based on the electrokinetic equations and the finite-element method to explain this phenomenon. As a proof of concept for the generality of this trapping mechanism we use our numerical model to explore the effect of the salt concentration, the capillary surface charge, the applied voltage, the pressure difference, and the mobility of the analyte molecules.

Reducing spurious flow in simulations of electrokinetic phenomena.

Electrokinetic transport phenomena can strongly influence the behaviour of macromolecules and colloidal particles in solution, with applications in, e.g., DNA translocation through nanopores, electro-osmotic flow in nanocapillaries, and electrophoresis of charged macromolecules.

Diffusiophoretic self-propulsion for partially catalytic spherical colloids.

Colloidal spheres with a partial platinum surface coating perform autophoretic motion when suspended in hydrogen peroxide solution. We present a theoretical analysis of the self-propulsion velocity of these particles using a continuum multi-component, self-diffusiophoretic model. With this model as a basis, we show how the slip-layer approximation can be derived and in which limits it holds.