Design and Vat-Photopolymerization 3D Printing of Customized Micromolds for Polymeric Microneedle Fabrication

This protocol presents a generalized, application-agnostic workflow for manufacturing polymeric microneedle (MN) patches using computer-aided design (CAD), vat-photopolymerization master fabrication (e.g., stereolithography or digital light processing, SLA/DLP), elastomer reverse molding, and single-fill casting. The method begins with parametric CAD of the MN geometry and array layout, including a thin patch base and an integrated reservoir to facilitate uniform cavity infiltration and limit thick rim formation at the patch perimeter. 3D-printing parameters are selected to preserve micro-feature integrity, followed by a brief solvent wash and controlled post-curing to remove residuals and stabilize features. The 3D-printed master is then replicated in an elastomer to yield a flexible reverse mold suitable for repeated casting cycles. Casting employs polymer solutions that are infiltrated into the mold via centrifugation or vacuum, enabling consistent cavity filling across a range of geometries. Representative quality assessments include inspection of the printed master and reverse mold for cavity completeness and defects, along with dimensional checks of needle height, base width, and tip quality at multiple array positions. The workflow accommodates multiple MN array model designs and is readily adapted to alternative polymer formulations by adjusting solution solids, viscosity, and drying conditions, enabling rapid, low-cost, and reproducible fabrication of polymeric MN patches suitable for research and prototyping.