Origin of electro-osmosis

Though the model presented and used does not give a complete account of the interface and the origin of measured electro-osmotic fluid mobility, it was proven useful in interpretation of surface properties. The range of electrolyte concentration that can be used in the manual particle electrophoresis chamber developed in this work is limited, and this limits the model of the origin of electro-osmosis that can be tested, such as inclusion of a Stern layer. 

In the following sections an account of the origin and measurement of electroosmosis is elicited, Furthermore, it is shown how to employ its measurement as a characterization technique. The discussion will focus on the measurement of electro-osmosis in cylindrical chambers and in a novel rectangular chamber whereby electro-osmosis can be measured at small sample plates. Examples of using the measurement of electro-osmosis as a surface characterization technique are discussed in terms of interpretation of the source of electro-osmosis according to classical electrokinetic theory. 

The parabola method makes it possible to measure the potential of cell walls. Usually, the cell is made of quartz, and the parabola method thus offers the possibility of determining the lEP of one material that has already been extensively studied. The potentials of macroscopic specimens of other materials can also be determined from the mobility profile [273-275] by replacement of the original cell wall of a commercial electrophoretic cell by a flat specimen of the material of interest. For example, in [276], the lEP of a basal plane of mica found from the mobility profile was different from the lEP of a mica dispersion. Only a few types of electrophoretic devices (most of which are no longer available on the market) can be used to determine potentials by means of electro-osmosis. 

For microchannels in which the flow is originated by means of electro-osmosis the hydrodynamic entrance... 

Electro-osmosis refers to the movement of the liquid adjacent to a charged surface, in contact with a polar liquid, under the influence of an electric field applied parallel to the solid-liquid interface. The bulk fluid of liquid originated by this electrokinetic process is termed electro-osmotic flow (EOF). It may be produced both in open and in packed capillary tubes, as well as in planar electrophoretic systems employing a variety of supports, such as paper or hydrophilic polymers. 

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