Many investigators have designed a variety of devices based on the Coulter principle, and generated peer-reviewed publications featuring data from these devices. Even today, some flow cytometers utilize the Coulter principle to provide highly accurate information about cell size and count. They are also routinely employed for quality control.Ī Coulter counter played an important role in the development of the first ever cell sorter, and was involved in the early days of the development of flow cytometry. Previously, this procedure involved preparing a peripheral blood smear and manually counting each type of cell under a microscope, a process that typically took a half-hour.Ĭoulter counters have a wide variety of applications including paint, ceramics, glass, molten metals and food manufacturing. The CBC is used to determine the number or proportion of white and red blood cells in the body. Its primary function is the quick and accurate analysis of complete blood counts (often referred to as CBC). The Coulter counter is a vital constituent of today's hospital laboratory. The size of the electric current change is related to the size of the particle, enabling a particle size distribution to be measured, which can be correlated to mobility, surface charge, and concentration of the particles. By monitoring such pulses in electric current, the number of particles for a given volume of fluid can be counted. If these particles are less conductive than the surrounding liquid medium, the electrical resistance across the channel increases, causing the electric current passing across the channel to briefly decrease. The principle has found commercial success in the medical industry, particularly in hematology, where it can be applied to count and size the various cells that make up whole blood.Ĭells, being poorly conductive particles, alter the effective cross-section of the conductive microchannel. The Coulter principle was named for its inventor, Wallace H. This pulse in impedance originates from the displacement of electrolyte caused by the particle. The Coulter principle states that particles pulled through an orifice, concurrent with an electric current, produce a change in impedance that is proportional to the volume of the particle traversing the orifice. 3.5 Direct current and alternating current.