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Measurement Principle of the VisiSensTM Imaging Systems - FRIM
Fluorescence Ratiometric Imaging (FRIM) is a method for reading out the signal of a fluorescent chemical optical sensor. Ratiometric measuring compensates most of the common interferences, e. g. inhomogeneous lightfields. An optical sensor foil contains an analyte sensitive dye and a reference dye which are immobilized in a permeable polymer matrix layer. The indicator dye is emitting red or green fluorescence, depending on the analyte and respective sensor foil type, which is dynamically quenched by the analyte while the reference dye is giving a constant green or red light signal respectively. These emissions meet exactly the red and green channel sensitivity of a color RGB chip.