Flow Cytometry, Instrumentation: Into the Black Box

Chapter Three (“Instrumentation: Into the Black Box”) covers the theory of flow cytometric instrumentation. Laser beam illumination of the stream is described, with discussion of the benefits of an elliptical beam profile. Then cytometer fluidics are explained, with description of the use of sheath fluid to center cells so that they flow one-by-one through the analysis point in the illuminating beam. The next section in this chapter covers the signals that are generated from cells after they are illuminated. Photodetectors detect and measure the light signals from cells. The sources of forward scatter and side scatter signals are explained as is the ability of a multi-parameter cytometer to detect fluorescence signals of different colors. The final section in this chapter explains the use of electronics (including logarithmic and linear amplifiers), of thresholding, and of the channels of an analog-to-digital converter, to convert the light signals from each cell to numbers that form the flow cytometric description of that cell.
10.1002/0471223948.ch3