ABSTRACT
Both the microfluidic and metrologie aspects of flow cytometry can be traced directly to Leeuwenhoek and Robert Hooke's work in the late 1600s. Staining and improvements in microscopy made in the mid-1800s led to better understanding of what cells were and how they worked, but it was not until the mid-20th century that it became possible to perform accurate and precise quantitative analyses of cells in flow systems. Flow cytometry will remain the method of choice for the most complex analytical tasks and for sorting; but the jobs done by the simpler, relatively inexpensive flow cytometers may soon be done by even simpler and less expensive boxes in which flow systems are conspicuous by their absence. By the late 1960's, several groups had explored fluorescence measurement as a means of improving both quantitative and qualitative analysis in cytometry.
