FACS

Fluorescence Activated Cell Sorting (FACS) is used to separate cells based on their fluorescent characteristics. Cells tagged with fluorescently labeled antibodies are loaded in a sample chamber and allowed to flow through a thin pipe in a continuous stream. As they flow, a laser is shined onto the cells and the emitted fluorescence is detected. A vibrating mechanism ensures that each ejected droplets carries one cell. Just before the droplets emerge from the stream, a charging ring places charge onto the cells in proportion to the intensity of their recorded fluorescence. As the cells move past electrically charged deflection plates, they are separated into two or more containers on the basis of their charge. FACS can be used in many different fields that require isolation of pure populations of cells based on marker expression, and can also be used to quantify properties of tagged cells. (Credit: Muhammad Atif Khan)