1. A biosensor for detecting and quantifying fluorescently-labeled biomolecules; said biosensor comprising a nanochannel defined between two substrates and containing one or several selectively functionalized areas on which are immobilized biomarkers, said nanochannel furthermore being defined by a lateral input aperture and a lateral output aperture, said input aperture being adapted to let a solution containing biomolecules to enter said nanochannel and said output aperture adapted to drive said solution through said nanochannel by capillarity.