Design of a confocal microfluidic particle sorter using fluorescent photon burst detection

An instrumental system is described for detecting and sorting single fluorescent particles such as microspheres, bacteria, viruses, or even smaller macromolecules in a flowing liquid. The system consists of microfluidic chips (biochips), computer controlled high voltage power supplies, and a fluorescence microscope with confocal optics. The confocal observation volume and detection electro-optics allow measurements of single flowing fluorescent particles. The output of the avalanche photodiode (single photon detector) is coupled to a real-time photon-burst detection device, which output can address the control of high voltage power supplies for sorting purposes. Liquid propulsion systems like electro-osmotic flow and plain electric fields to direct the particles through the observation volume have been tested and evaluated. The detection and real-time sorting of fluorescent microspheres are demonstrated. Applications of these biochips for screening of bacteriophages-type biolibraries are briefly discussed.