Abstract: An ultra-miniature personal flow cytometer (pFCM) for the measurement of laser-induced fluorescence. The pFCM is approximately the size of a fluorescent microscope and includes a miniature optical module onto which the flow cytometry components are coupled. The miniature optical module is closely integrated with a flow cell through which a sample cell stream flows. The advantage of the pFCM is its compact size and efficiency that is made possible due to the unique microchip demultiplexing waveguide utilized in the separation of fluorescent wavelengths. The microchip demultiplexing waveguide is wholly contained in a tiny microchip consisting of a wave channel layer, a buffer layer, a substrate layer, and a plurality of micrograting filters. Photodetectors may either be coupled to the microchip demultiplexing waveguide by individual fiber optic members or incorporated into the wave channel layer in a photodiode array.