Flow Cytometry :: Introduction

Principles of Flow Cytometry

Flow cytometers are instruments that determine the characteristics of cells in a complex mixture. Cells (or other biological particles) are led in a stream past an illumination and light detection system. As the cells traverse the illumination spot one by one, a microscope objective collects the scattered and fluorescence light from the cells and directs it to a set of photomultipliers. Temporal, spatial and chromatic filters eliminate background light and separate the signals from different fluorophores. Digital acquisition electronics measure the intensity of the light pulses from each of the photomultiplier tubes.

A cell sorter adds a means for separating cells of interest from the heterogenoeus mixture after they have been measured and classified.

 An animation can be seen here.