What is electrokinetic flow?
Electrokinetic flow is the fluid motion generated by an external electric field1,2. It has a much smaller resistance than the traditional pressure-driven flow3, and is the preferred mode for transport of fluids and samples in microfluidic devices4,5,6,7.
Why does electroosmotic flow occur?
Electroosmotic flow occurs because the walls of the capillary tubing carry a charge. The surface of a silica capillary contains large numbers of silanol groups (–SiOH). At a pH level greater than approximately 2 or 3, the silanol groups ionize to form negatively charged silanate ions (–SiO–).
Why electrophoresis is an electrokinetic phenomenon?
Electrokinetic phenomena are typically second-order phenomena, in that forces of a certain kind create fluxes or flows of another type. For instance, in electrophoresis an electric force leads to a mechanical motion and in streaming current (see below) an applied mechanical force produces an electric current.
What is electroosmotic flow of ions?
Definition. Electroosmotic flow is the bulk liquid motion that results when an externally applied electric field interacts with the net surplus of charged ions in the diffuse part of an electrical double layer.
How does electro osmosis work?
According to the chemistry web dictionary at www.chemicool.com, the definition of electroosmosis is “the process by which charged particles will tend to migrate toward a less charged area.” Electroosmosis is typically discussed with regard to its influence on the flow characteristics of charged analytes in capillary …
How does electro-osmosis work?
How can electroosmotic flow be reduced?
Electroosmotic flow can be reduced by coating the capillary with a material that suppresses ionization of the silanol groups, such as polyacrylamide or methylcellulose.
Which of the following is electrokinetic phenomena?
The four main electrokinetic phenomena are electrophoresis, electroosmosis, streaming potential, and sedimentation potential, or Dorn effect. These phenomena are related to one another through the zeta potential ζ of the electrical double layer that exists in the neighborhood of the charged surface.
How do you calculate electroosmotic flow rate?
For example, if we apply 300 V along a 1-cm-long microchannel of r = 50 μm, the electro-osmotic velocity will be uEOF = 2.13 mm/s and the corresponding volumetric flow rate will be Q = 1 μL/min, when ε = 7.1 × 10–10 F/m, ζ0 = -0.1 V, and μ = 0.001 N s/m2.