ImQuant — An image based fluorescence reader for quantitative lateral flow immunoassays

Fluorescence immunoassays (FIA) have strong potential in enabling rapid quantitative immunological testing at point of care. Existing state of the art instruments employ laser scanning of FIA test kits, which require the use of electromechanical systems, making the instrument bulky, heavy and less reliable in the long term. There is a growing need for an extremely compact and reliable, motion-free, automated reader for accurate quantification of immunoassays. Here, we present ImQuant, an image based FIA reader with integrated monochromatic excitation source, optical filtering and real time image capture, assisted with an intuitive graphical user interface. A 12bit dynamic range RAW ouput CMOS camera with 1/3” sensor format and a sharp cut off wideband filter were utilized to ensure improved accuracy. A laboratory prototype was constructed and tested using a set of stable reference cartridges that provided repeatable fluorescent lines. The ImQuant could capture the lines and measure area ratios with coefficient of variation (CV) less than 2%. Further, tests with blood samples on Quanti
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HbA1C test kits also demonstrated good repeatability with CV<;2%. The ImQuant is a novel platform of motion-free fluorescent scanning of FIA immunoassays and is being used for developing a variety of test kits and instruments.