Parallel processing data acquisition system for multilaser flow cytometry and cell sorting

This report describes the data acquisition electronics for a flow cytometer. The design differs from most instruments in that the signals from a large number of detectors are processed in parallel. Each of the input channels is capable of autonomously measuring and digitizing the fluorescence signals. The digitized values that belong to one particle are collected by digital circuitry and are presented as a compact data package on a special bus. In addition to the pulse values, the data package contains a time marker, information needed for sort decisions, and an error detection code. Specially designed electronic modules that read the information from the bus can take complex multiparameter sort decisions at a very high speed. All events can also be recorded as data lists by a computer. The lists can be used to reconstruct a sort or analysis run. The raw data lists can also be reduced to kinetic curves and/or (gated) multivariate histograms. As a result of the applied scheme of parallel pulse processing, the dead time of the system is independent of the number of parameters measured and the number and time separation of the excitation beams. The instrument has a cycle time of 5 microseconds, which corresponds to a throughput rate of 2 x 10(5) events/s. At this rate, the incidence of correlation errors is well below 1 in 10(8) analyzed particles. The system has proved to be reliable and convenient to use in a variety of experiments. Its high speed and low error rate make it well suited for high-resolution measurements, rare-event analysis, kinetic measurements, and high-speed cell sorting.