electrokinetic

Electrokinetics is the study of motion and forces arising from electric fields acting on charge carriers in a medium, typically a liquid or porous solid. It encompasses the interaction between electric fields and charged species such as ions, colloidal particles, and charged surfaces, leading to bulk fluid flow, particle transport, and related electrical signals.

The field includes several principal phenomena. Electrophoresis refers to the movement of charged particles through a fluid under an applied electric field. Electroosmosis, or electroosmotic flow, is the bulk movement of liquid induced by the electric field across a charged surface or porous medium. Streaming potential arises when a pressure-driven flow generates an electrical potential due to the separation of charges in the electric double layer. Dielectrophoresis describes the motion of neutral but polarizable particles in non-uniform electric fields. Collectively, these effects enable control and analysis of micro- and nanoscale systems.

The underlying physics involves charged interfaces and the electric double layer formed at solid–liquid boundaries. Key concepts include zeta potential, Debye length, and the slip plane that governs electroosmotic motion. Mathematical relationships such as the Smoluchowski equation relate electroosmotic velocity to the electric field and surface charge, while electrophoretic mobility links particle charge to its velocity in an electric field.

Applications span microfluidics and lab-on-a-chip technologies, electrophoretic deposition of coatings, and environmental remediation using electric fields to enhance contaminant transport. In analytical chemistry, capillary electrophoresis and related methods rely on electrokinetic transport. Limitations include sensitivity to solution conductivity, pH, and temperature, as well as practical challenges from electrode reactions and Joule heating in real systems.