Microelectrophoresis is a method of studying electrophoresis

Electrophoresis

Electrophoresis, also called cataphoresis, is the motion of dispersed particles relative to a fluid under the influence of a spatially uniform electric field. This electrokinetic phenomenon was observed for the first time in 1807 by Reuss , who noticed that the application of a constant electric...

 of various dispersed particles using optical microscopy

Microscopy

Microscopy is the technical field of using microscopes to view samples and objects that cannot be seen with the unaided eye...

. This method provides image of moving particles, which is its unique advantage.

Complexity of this method is associated with electro-osmosis

Electro-osmosis

Electroosmotic flow is the motion of liquid induced by an applied potential across a porous material, capillary tube, membrane, microchannel, or any other fluid conduit...

 generated by electric field

Electric field

In physics, an electric field surrounds electrically charged particles and time-varying magnetic fields. The electric field depicts the force exerted on other electrically charged objects by the electrically charged particle the field is surrounding...

 influence on the double layers of the sample cell walls. In the usually used closed cells this creates Poiseuille type back flow, leading to parabolic

Parabola

In mathematics, the parabola is a conic section, the intersection of a right circular conical surface and a plane parallel to a generating straight line of that surface...

 velocity profile. There are two stationary layers, where fluid does not move. Position of these stationary layer regarding cell walls depends on the cell geometry

Geometry

Geometry arose as the field of knowledge dealing with spatial relationships. Geometry was one of the two fields of pre-modern mathematics, the other being the study of numbers ....

. It is possible to focus

Focus (optics)

In geometrical optics, a focus, also called an image point, is the point where light rays originating from a point on the object converge. Although the focus is conceptually a point, physically the focus has a spatial extent, called the blur circle. This non-ideal focusing may be caused by...

 microscope

Microscope

A microscope is an instrument used to see objects that are too small for the naked eye. The science of investigating small objects using such an instrument is called microscopy...

 on this stationary layers and observe particles motion not affected with electro-osmosis.

The second complexity comes from necessity of diluting sample, if it was initially concentrated. Concentration must be sufficiently low for observing individual particles.

Measurement in the low polar

Chemical polarity

In chemistry, polarity refers to a separation of electric charge leading to a molecule or its chemical groups having an electric dipole or multipole moment. Polar molecules interact through dipole–dipole intermolecular forces and hydrogen bonds. Molecular polarity is dependent on the difference in...

 fluids present additional problems. These systems have low electrical conductivity and low dielectric permittivity. Electrophoretic mobility is low and this requires high electric field, by factor 10 and higher.

Details of this method are presented in IUPAC Technical Report prepared by a group of most known world experts on the electrokinetic phenomena

Electrokinetic phenomena

Electrokinetic phenomena are a family of several different effects that occur in heterogeneous fluids or in porous bodies filled with fluid. The term heterogeneous here means a fluid containing particles...

.