Coulter principle particle counting

The electrozone sensing technique, also called the Coulter principle, was originally developed for biomedical applications for counting blood cells. This method counts and sizes particle based on changes in the electrical resistance caused by nonconductive particles suspended in an electrolyte. It presently finds uses in a wide variety of industries, including the food, environmental, coatings, ceramics, and metals industries. 

The Coulter principle was patented in 1949 [2] and described in 1956 [3] as a method for counting and sizing blood cells. Kubitschek [4,5] introduced modifications which permitted the counting of bacterial cells, and pointed out that the method could be applied to the measurement of cell volumes as well as number counting. Modified instruments were soon developed with which particles could be sized as well as counted. In 1998 the company was acquired by Beckman and renamed Beckman Coulter. 

One of the earliest electronic particle sizing devices available was developed in the late-1940 s and was originally designed to count blood cells (Coulter, 1956). The Coulter Counter rapidly gained immense popularity in many industry and research applications, including the Earth sciences, and is still a very commonly used instrument in sedimento-logical laboratories. The Coulter Principle is sufficiently well established to be included in many A.S.T.M. (American Society for Testing Materials) reference method standards. 

The Coulter Counter, through its various models, has become an estabi ished and we I I evaluated method of counting and sizing particles. The Coulter principle, or better, the electrical sensing zone method, has been the subject of many publications, including textbooks and the British Standard 3406. The main advantage of this method is that it yields directly a number distribution of the equivalent volume diameter. 

The Coulter Counter (Coultronics) [102-105] is able to measure the sizes of individual particles and aggregates in very dilute suspensions (for counting, aliquots of the suspension were usually diluted up to one hundred times). The principle of the counter is that the colloid moves in a suspending electrolyte (whose composition and pH is equal or very close to that of the solvent employed in the experiments) through a constricted electrical current path. An aperture is set in the wall of an insulated vessel, and direct current is applied across a pair of electrodes, one situated inside the insulated vessel, the other outside in the suspension. The passage of each visible colloid... 

The Coulter Counter method provides facilities for both counting and sizing particles and its counting principle has a volume basis, which should allow the exact calculation of the particulate volume. In particular the method we proposed was essentially based on the comparison between the total particulate volume of a disintegrant as measured in a swelling and in an inert medium. 

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