The technology described herein generally relates to microfluidic cartridges configured to amplify and detect polynucleotides extracted from multiple biological samples in parallel. The technology includes a microfluidic substrate, comprising: a plurality of sample lanes, wherein each of the plurality of sample lanes comprises a microfluidic network having, in fluid communication with one another: an inlet; a first valve and a second valve; a first channel leading from the inlet, via the first valve, to a reaction chamber; and a second channel leading from the reaction chamber, via the second valve, to a vent.