The study of rare cell populations is important to advance medical diagnostics and therapeutics. For many clinical studies, rare cell counts promise to provide valuable alternate end points; examples are circulating tumour cells in peripheral blood, tumour stem cells, endothelial cells in blood, hematopoietic progenitor cells and their subpopulations, antigen specific T-cells and foetal cells in maternal circulation.

Flow cytometry is an established technology used in many research and clinical laboratories. The largest users are immunologists and haematologists who use it for cell sorting and analysis. Increasing requirements for processing larger numbers of patient samples led to the development of automated tube loading carousels and, later, multiwell plate-based sampling systems.

Commercial flow cytometers became widely established in research and clinical laboratories in the 1980s. Once the domain of immunologists and hematologists for cell sorting and analysis, the need for sample handling beyond manual delivery of single flow cytometry samples became apparent. Automated sample handling carousels subsequently evolved into multiwall plate-based sampling systems. In parallel, data acquisition and data analysis were advanced with automated and batch processing systems.