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The Coulter principle states that particles pulled through an orifice, concurrent with an electric current, produce a change in impedance proportional to the volume of the particle traversing the orifice. This pulse in impedance originates from the displacement of electrolyte caused by the particle.
The Coulter principle uses electrical impedance measurements to count blood cells and determine their sizes; it is a technology that remains in use in many automated analyzers. Further research in the 1970s involved the use of optical measurements to count and identify cells, which enabled the automation of the white blood cell differential.
Celloscope automated cell counter was developed in the 1950s for enumeration of erythrocytes, leukocytes, and thrombocytes in blood samples. [1] Together with the Coulter counter, the Celloscope analyzer can be considered one of the predecessors of today's automated hematology analyzers, as the principle of the electrical impedance method is still utilized in cell counters installed in ...
Hematology analyzers are used to conduct a complete blood count (CBC), which is usually the first test requested by physicians to determine a patient's general health status. [5] A complete blood count includes red blood cell (RBC), white blood cell (WBC), hemoglobin, and platelet counts, as well as hematocrit levels.
The first impedance-based flow cytometry device, using the Coulter principle, was disclosed in U.S. Patent 2,656,508, issued in 1953, to Wallace H. Coulter.Mack Fulwyler was the inventor of the forerunner to today's flow cytometers – particularly the cell sorter. [6]
Flow cytometry is by far the most sophisticated and expensive method for cell counting. In a flow cytometer the cells flow in a narrow stream in front of a laser beam. The beam hits them one by one, and a light detector picks up the light that is reflected from the cells.
Electrical impedance measurements may also be used to calculate abstract parameters, i.e. nonvisual information. Recent advances in EIT technology as well as the lower number of electrodes required for recording global instead of regional parameters in healthy individuals can be used for non-invasive determination of e.g. VO 2 or arterial blood ...
Electrical analysis involves passing a dilute solution of the blood through an aperture across which an electrical current is flowing. The passage of cells through the current changes the impedance between the terminals (the Coulter principle). [6]