Scalable fabrication of microneedle arrays via spatially controlled UV exposure

This paper describes a theoretical estimation of the geometry of negative epoxy-resist microneedles prepared via inclined/rotated ultraviolet (UV) lithography based on spatially controlled UV exposure doses. In comparison with other methods based on UV lithography, the present method can create microneedle structures with high scalability. When negative photoresist is exposed to inclined/rotated UV through circular mask patterns, a three-dimensional, needle-shaped distribution of the exposure dose forms in the irradiated region. Controlling the inclination angles and the exposure dose modifies the photo-polymerized portion of the photoresist, thus allowing the variation of the heights and contours of microneedles formed by using the same mask patterns. In an experimental study, the dimensions of the fabricated needles agreed well with the theoretical predictions for varying inclination angles and exposure doses. These results demonstrate that our theoretical approach can provide a simple route for fabricating microneedles with on-demand geometry. The fabricated microneedles can be used as solid microneedles or as a mold master for dissolving microneedles, thus simplifying the microneedle fabrication process. We envision that this method can improve fabrication accuracy and reduce fabrication cost and time, thereby facilitating the practical applications of microneedle-based drug delivery technology. Microstructures: Fabrication gets to the point A cheap and quick method for producing micrometer-scale needles for painless drug delivery has been developed by researchers in Japan. Yun Jung Heo at Tokyo University of Agriculture and Technology and Isao Shimoyama at the University of Tokyo and their co-workers used ultraviolet light and a light-sensitive polymer to mass-produce arrays of microneedles that could offer an easier way for people to self-deliver therapeutic drugs beneath the skin. The team exposed a thin film to the ultraviolet radiation through a mask composed of a grid of circles. The light was shone at an angle, and the substrate rotated. A solution process then removed the exposed material, leaving behind the unexposed material in the shape of a sharp needle. The researchers calculated the optimum intensity and exposure time to ensure highly accurate fabrication of the array.