A microarrayer for dispensing reagent onto a substrate, comprising a dispensing print head adapted to load reagent and provided with a plurality of nozzles to dispense said at least reagent on the substrate, wherein the print head is mounted in the microarrayer to allow the print head to move with respect to the substrate in subsequent, essentially, parallel print passes, wherein the print head moves during a first print pass between a first end of the substrate toward a second end of the substrate and during a subsequent printpass in the opposite direction, the microarrayer being characterised in that the microarrayer comprises a first camera adapted to move behind the print head during a print pass and a second camera adapted to move ahead of the print head during said print pass, the first and second camera being adapted to obtain images of the substrate.