ABSTRACT
Microfluidics is a multidisciplinary research field involving engineering, physics, chemistry, micro-technology, and biotechnology. Microfluidic systems have been shown to have great potential in diverse areas of biological applications, including diagnosis, drug delivery and therapeutics, biomolecular separations, bioassays, immunohybridization assays, and polymerase chain reactions. The most important characteristic of microfluidic devices is the dominant role of viscosity when compared to fluid velocity. The flow of liquid in microfluidic devices is regulated by a large variety of applied forces, such as pressure differences, electrophoresis capillary forces, or Marangoni forces, by controlling spatial variations of surface tension. Most fluidic devices that produce internal flows use electrophoresis, electroosmosis, electrohydrodynamics, magnetohydrodynamics, centrifugation, or pressure gradient. The spontaneous separation of charges at solid-liquid interfaces, determined by the ionization of surface groups, is central to electrokinetic actuation of flows in microfluidic devices. Surface electrodeposition on solid electrolytes can be used to control the flow in microfluidic devices.
