Wallace Coulter, born in 1913 in Little Rock, Arkansas, is perhaps best known for his discovery of the Coulter principle, an electronic method for counting and sizing microscopic particles suspended in a fluid. His early interest in radio sets and electricity led him to study electrical engineering at Georgia Institute of Technology. Between 1934 and the start of World War II, Coulter held many jobs; he was a radio station engineer and announcer, a Far East sales and service representative for General Electric X-ray Corporation, and an electromedical instrumentation developer for Raytheon Manufacturing Company.
In 1948 Coulter discovered the Coulter principle of volumetric impedance, which is based on displacement as a measure of volume. Blood cells suspended in a conductive fluid can be counted because the cells will displace their own volume of electrolyte as they pass between electrodes. A measurable change in the electrical resistance to the system occurs, and this change can be used as a precise measure of cell volume.
Soon after this discovery, Coulter invented the Coulter counter—the first of his seventy-four patents, the catalyst for a lifetime of groundbreaking inventions, and the foundation for the Coulter Electronics Corporation. Incorporated in 1958 by Wallace and his brother, Joe, the Coulter Corporation grew out of a Chicago basement into a multinational industry leader in the field of blood-cell analysis systems. The Coulter counter enabled improvements not only in hematology but also in fine industrial particle counting. The Coulter brothers also worked on developing monoclonal antibodies for cancer diagnosis and flow cytometry systems that have lasers to detect cell signatures.
Wallace Coulter received many awards during his long and distinguished professional life. Among these were the John Scott Award for Scientific Achievement, the Morris E. Leeds Award of the Institute of Electrical and Electronic Engineers, and the Florida Industrialist of the Year Award. The American Society of Hematology gave him the Certificate of Distinguished Achievement, and the Association of Clinical Scientists presented him with a Gold-Headed Cane Award. Coulter was also inducted into the National Academy of Engineering and was elected a founding fellow of the American Institute of Mechanical and Biological Engineering in 1992.
Wallace Coulter (left) with an employee, ca. 1953. Courtesy of Beckman Coulter.