Electrokinetics

Electrokinetics is a field of study that explores the interplay between electric fields and fluid motion, particularly in systems containing charged interfaces. It encompasses phenomena where the movement of ions or charged particles within a fluid induces or is influenced by an electric field. Key electrokinetic effects include electrophoresis, electroosmosis, sedimentation potential, and streaming potential.

Electrophoresis describes the movement of charged particles in a fluid under the influence of an applied electric field. This principle is widely used in analytical techniques like gel electrophoresis to separate molecules based on their charge and size. Electroosmosis, conversely, refers to the bulk fluid flow generated when an electric field is applied across a porous material or a capillary tube that has a charged surface. This effect is utilized in microfluidic devices and separation technologies.

Sedimentation potential arises when charged particles settle under gravity in a fluid, creating an electric potential difference. This is essentially the inverse of electrophoresis. Streaming potential is the electric potential generated when a fluid flows through a charged channel or porous medium, creating an ion imbalance that leads to a potential difference.

These electrokinetic phenomena are crucial in various scientific and engineering disciplines, including colloid science, microfluidics, material science, and biotechnology. Understanding and manipulating electrokinetic effects allows for the design of novel devices for sensing, separation, pumping, and drug delivery. The behavior of electrokinetic phenomena is governed by factors such as the surface charge density, fluid properties, and the applied electric field strength.