Applications of Induced-Charge Electrokinetic

Applications of Induced-Charge Electrokinetic in Microfluidics, Fig. 1 (a) The computational domain of the proposed ICEK microvalve with three microchannels and one suspended Janus particle In it. i, and 2,... 

Applications of Induced-Charge Electrokinetic in Microfluidics, Table 1 Constants used for our numerical simulation... 

Applications of Induced-Charge Electrokinetic in Microfluidics, Fig. 4 Flow pattem and concentration distribution in the micromixer. The red lines inside the microchamber represent the streamlines of the flow field. The color bar shows the concentration distribution. The figure shows a micromixing chamber (a) without a particle inside, (b and c) with a conducting particle at different... 

The technology involves the application of low-intensity, direct electrical current across electrode pairs that have been implanted on each side of the contaminated soil. The electrical current induces electroosmosis and ion migration between the two implanted electrodes. Depending on their charge, the contaminants accumulate on one of the electrodes and are extracted to a recovery system (Fig. 14.4). Improved performance of electrokinetics could be attained by the introduction of surfactants. 

In addition to conventional pressure driven flow, electrokinetic flow is also a commonly used means of transporting liquids in microfluidic devices. One type of electrokinetic flow, electroosmotic flow, relies on the presence of an electrical double layer at the solid-liquid interface. A negatively charged surface in a flow channel will attract cationic species from the fluid to form an electrical double layer at the surface. Application of an external voltage can pull those cationic species through the flow channel inducing bulk flow. The electroosmotic flow velocity can be described... 

The motion of electrically charged particles or molecules in a stationary medium under the influence of an electric field is called electrophoresis. In such transport the electric force is applied through a potential difference between electrodes. Selective use of the Lorentz force by applying a magnetic field can also induce such movement. Electrophoresis and electroosmosis are two key modalities of electrokinetic transport which are very useful in micro- and nanofluidics for a variety of applications including biomedical (bio-NEMS, etc ), fuel cell and micro total analysis systems ( x-TASs). In electroosmosis the bulk fluid moves due to the existence of a charged double layer at the solid-liquid interface. While onedimensional electrophoresis is more commonly used, two-dimensional electrophoresis may also become a useful tool for the separation of gel proteins based on isoelectric property. 

Electrokinetic phenomena, namely electrophoresis, electro-osmosis and streaming potential are discussed in Vol. 1 at a fundamental level. These effects arise because of charge separation at the interface that is induced for example by application of an electric field. The plane at which the liquid starts to move is defined as the shear plane and the potential at this plane is defined as the electrokinetic or zeta potential. A schematic picture is given that describes the shear plane and zeta potential. The latter is mostly assumed to be equal to the Stern potential and in the absence of specific adsorption it can be equated to the surface potential, which is the parameter... 

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