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This paper presents a polymer hollow microneedle array for transdermal drug delivery that is fabricated using UV photolithography and a single-step micromolding technique. This fabrication process patterns a 6×6 array of 1mm tall high-aspect-ratio hollow microneedles with sharp beveled tips and 150µm diameter side-opened lumens. The geometry of the beveled tip and the position of the lumen are defined simultaneously by a two-dimensional lithography mask pattern and the topography of the micromold. This three-dimensional geometry improves insertion performance and potentially the drug delivery efficiency without additional fabrication processes. These hypodermic-needle-like microneedles have been successfully constructed, packaged, and tested for fluidic functionality and skin penetrability.

This paper presents a fabrication process combining micromolding and direct drawing, and its application to the development of high aspect ratio microneedles. Without using photolithography or etching, the proposed process creates microneedles with: 1) higher aspect ratios than that of the original mold, 2) controllable needle diameter for optimized mechanical strength, and 3) arrowhead-shaped tips for potentially increased capacity and effective payload delivery. The needles presented are formed with biocompatible, water-soluble polymers, but the fabrication process inherently allows many kinds of polymers to be exploited. Various high aspect ratio 3D structures were fabricated and characterized, and the fabrication result was compared with theoretical prediction. Water-soluble microneedle arrays have been fabricated and successfully penetrated into porcine skin, fully releasing the drug-surrogate into the dermis layer within a minute.