A blood cell counter system on display at what is likely a trade show. This technology is based on the Coulter principle and the the Coulter Counter, which quantifies and sizes particles suspended in a fluid, like blood cells, bacteria, and a wide variety of other substances. The Coulter principle was discovered by Wallace H Coulter in the late 1940s and patented in 1953. The Coulter counter was manufactured by Coulter Corporation until 1997, when the company was acquired by Beckman Instruments and became known as Beckman Coulter, Inc.