Figure 3  Schematic illustration of key steps in microintaglio printing (µIP) for the in situ fabrication of microarrays. A microengraved intaglio plate (micromold plate) consisting of a dense array of microchambers (a) is filled with the precursors of biomolecular “ink” (e.g., single-DNA molecule-amplified bead carrier or messenger RNA-immobilized bead carrier) (b); A glass substrate, one surface of which is modified to capture the biomolecular ink, is used to sandwich the cell-free system (e.g., coupled transcription/translation system or translation system) and seal the microchambers (c); The filled microchambers are placed in contact at a temperature for the in situ synthesis of the biomolecular ink within the microchambers (d); and the synthesized biomolecular ink (e.g., proteins) is then diffused and captured on the glass substrate (e). The assembly is peeled off to release the printed protein microarrays from the corresponding DNA microarrays.