Controlling microarray spot morphology with polymer liftoff arrays.

Biological arrays are hindered by the lack of uniformity in the deposition of biomaterials. Efforts aimed at improving this deposition have focused on altering the composition of the solution or the tool used to deposit the material. However, little attention has been paid to controlling material deposition by constraining the physical and chemical topography of the surface. Here we present the use of a hybrid hydrophilic/hydrophobic micropatterned surface to direct the deposition of spotted DNA on microarrays. These polymer "liftoff" arrays combine the hydrophobic surface properties of di-p-xylylene (Parylene) with photolithographically etched hydrophilic openings within the polymer. We show that the flow pattern of solutes on these substrates favors the concentration of dissolved material into the mesoscopic openings underlying the printed spot, resulting in significantly improved uniformity of deposition. Moreover, the micropatterned surface allows for increased replication of spotted materials. Finally, these polymer liftoff arrays display reduced array-to-array variation, improving the reproducibility of data acquisition. We envision that these novel substrates can be generalized to produce more uniform arrays of other patterned biomaterials.