Figure 4. Fabrication of the mask for SU-8 selective polymerization by depositing Al thin film only inside the microchannel.

Glass flat slide (a), deposition of positive resist over this slide and then pre-bake (b), UV exposure, development producing the mask for microchannel pattern transfer, and hard bake (c), glass etching (d), deposition of opaque thin film by sputtering over all of the slide (e), and lift-off with the thin film only inside the etched cavity (f). Features not drawn to scale.