Patterned Screen‐Printing Process for Substrate‐Free and Scalable Hyaluronic Acid Microneedle Arrays

ABSTRACT

Dissolving hyaluronic acid (HA) microneedles (MNs) offer a promising platform for transdermal drug delivery, yet conventional micromolding processes struggle with void‐free fabrication, large‐area scalability, and residual substrates that reduce patch flexibility on contoured skin. To overcome these limitations, we propose a screen‐printing‐based fabrication process to produce substrate‐free and scalable HA MN arrays. To improve mold filling capabilities and support the formation of solid, void‐free MNs, a hybrid HA ink blending low and high molecular weight HA was utilized. A vacuum‐assisted jig was employed to facilitate the rapid and uniform infiltration of the viscous ink into the cavities of polydimethylsiloxane (PDMS) molds. Furthermore, a “delayed drying system” utilizing a stepwise steam flow was applied to manage the evaporation rate, effectively preventing premature drying and ensuring the formation of void‐free, solid MNs. Notably, the proposed process achieved a production yield of approximately 95% for 21 × 21 arrays. The fabricated MNs exhibited structural uniformity and mechanical stability, demonstrating skin penetration and drug delivery in ex vivo porcine skin models. Multi‐drug loaded and patterned arrays were also successfully fabricated using various mask designs, confirming process versatility. This work presents a scalable and flexible manufacturing strategy for transdermal drug delivery systems.