apparatus and methods are provided for a microfabricated fluorescence activated cell sorter based on an optical switch for rapid , active control of cell routing through a microfluidic channel network . this sorter enables low - stress , highly efficient sorting of populations of small numbers of cells . the invention includes packaging of the microfluidic channel network in a self - contained plastic cartridge that enables microfluidic channel network to macro - scale instrument interconnect , in a sterile , disposable format .