A cartridge includes a substrate including a polymerase chain reaction (PCR) zone. The PCR zone includes a first heating region, a second heating region spaced away from the first heating region and a detection region. A microchannel is formed in the substrate. The microchannel receives a fluid flowing therethrough, the microchannel passing through the first heating region and second heating region to thermally cycle the fluid. The microchannel passes through the detection region after the fluid has been thermally cycled.