An assay unit for carrying-out fluorescence-detected assays on one or more physiological samples, comprises a microfluidic chip with a microfluidic system that is able to convey a physiological sample or analyte solution (25) through one or more microfluidic channels (30) arranged on the chip, and a photonic system with one or more planar waveguide structures (62, 66, 63) arranged on the chip that are able to guide excitation light (64, 65) in the near IR, visible, or near UV range. The one or more microfluidic channels and the one or more waveguide structures cross each other at a detection site (26). In an assay area (32), where a certain microfluidic channel and a certain waveguide structure cross each other, one or more surfaces of the core of the waveguide structure (66) at least partially face the inner volume of the microfluidic channel. In the assay areas (32), one or more capture spots are located on the surface of the waveguide core, the capture spots comprising a coating of capture antibodies of th
