An apparatus is provided for performing an chemical, biochemical, or biological assay on a sample comprising: a microfluidic assay cartridge (1) that contains at least one sample inlet well (2) configured to receive a sample; and a microfluidic sub-unit (3) associated with the microfluidic assay cartridge (1) and comprising microfluidic channels (8), micro-valves (4, 4a, 9) and at least one separate and fluidicly-isolated isolation channel (5), and at least one hollow element (14); the at least one hollow element (14) being functionalized with a capture moiety or molecules (15) so as to form at least one reaction vessel (19); the microfluidic channels (8) and micro-valves (4, 4a, 9) configured to respond to signaling containing information about performing the assay and to controllably receive the sample and at least one reagent in the at least one reaction vessel (19), and to provide from the at least one reaction vessel (19) light containing information about the assay performed on the sample inside the at least one reaction vessel (19) as a result of said at least one reagent.