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[1] [2] [3] During the 1950s, laboratory technicians counted each individual blood cell underneath a microscope. Tedious and inconsistent, this was replaced with the first, very basic hematology analyzer, engineered by Wallace H. Coulter. The early hematology analyzers relied on Coulter's principle (see Coulter counter). However, they have ...
The Coulter counter is the commercial term for the technique known as resistive pulse sensing or electrical zone sensing. The apparatus is based on the Coulter principle named after its inventor, Wallace H. Coulter. A typical Coulter counter has one or more microchannels that separate two chambers containing electrolyte solutions.
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 ...
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.
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 ]
In electrical engineering, impedance is the opposition to alternating current presented by the combined effect of resistance and reactance in a circuit. [1]Quantitatively, the impedance of a two-terminal circuit element is the ratio of the complex representation of the sinusoidal voltage between its terminals, to the complex representation of the current flowing through it. [2]
Joseph and Wallace Coulter circumnavigates these difficulties by inventing the principle of using electrical impedance to count and size microscopic particles suspended in a fluid. [5] [13] This principle is today known as the Coulter principle and was used in the automated blood cell counter released by Coulter Electronics in 1954.
Blood is sampled and diluted, and moves through a tube thin enough that cells pass by one at a time. Characteristics about the cell are measured using lasers (fluorescence flow cytometry) or electrical impedance. Because not everything about the cells can be measured at the same time, blood is separated into a number of different channels.