Development of a Rapid Prototyping System for Microneedles Using Moving-mask Lithography with Backside Exposure

Abstract

Moving-mask lithography with backside exposure was utilized to generate master male mold for biodegradable polymer microneedle production. The microneedle shape was calculated from the exposure dose, mask geometry, and moving trajectory using a newly developed computer simulation. Two conditions (90 µm aperture with 80 µm diameter of circular movement, and 90 µm aperture with 90 µm diameter of circular movement) were selected to evaluate the moving-mask exposure effectiveness. By changing the moving trajectory, two different sizes of microneedles were obtained from a single-size aperture mask. The fabricated microneedle and calculated microneedle geometry showed good qualitative agreement. The geometrical difference was 2% in basal diameter and 8%-16% in height. Using the master male mold, biodegradable polymer microneedles made of chondroitin sulfate C sodium salt (CSC) were fabricated by casting from a poly-dimethylsiloxane female mold. The shape of the biodegradable CSC microneedles showed good agreement with the master male mold.

A biodegradable microneedle sheet for intracorporeal topical hemostasis

“…1 b). Following post-exposure bake, development, rinse, and drying with nitrogen blow, a master mold of the microneedle was obtained 5 , 6 . The shape of the master mold was transferred by poly-dimethyl siloxane (PDMS) (Sylgard 184, Dow Corning Corp, Midland, MI, USA) to be a female mold (Fig.…”

“…According to a previous study of wound healing 6 , Masson's trichrome stain histological data were digitalized and transferred to ImageJ (National Institutes of Health, Bethesda, MD, USA). As with macrophages per area analysis, the ROI was set for visible liver tissue at 20 × magnification.…”

Accessible, large-area, uniform dose photolithography using a moving light source

“…Alternatively, several researchers have suggested introducing moving components into the photolithography process. For example, moving-mask lithography can be used to create complex 3D structures [17,18]; and a rotating array of UV diodes has been demonstrated to create a uniform exposure pattern [19]. However, these systems still require expensive large-area LED arrays or complex control systems and subjectspecific expertise to develop.…”