(The) fabrication of microneedle array using inclined LIGA process

Abstract

In this thesis, we present a novel fabrication technology for micro needle array fabrication, which can be used in the medical application like transdermal drug delivery and blood analyte sampling. To overcome geometric constraint, we developed an inclined LIGA process for the fabrication of micro needle array. In microneedle fabrication methods employed to date, researchers have used conventional silicon-based fabrication methods such as inductively coupled plasma etching and wet etching techniques. However, these processes are not sufficient for the fabrication of a longer needle shank and applications such as blood extraction from the skin surface. This process provides easier fabrication method than conventional silicon based fabrication process to make sharp, robust and HAR(High Aspect Ratio) out-of-plane micro needle array structure. Using a deep x-ray, high-aspect-ratio (HAR) 3D microstructures can be fabricated. The fabrication process consists of a vertical deep x-ray exposure and a successive inclined deep x-ray exposure. The first vertical exposure makes a triangular column array with a needle conduit through a deep x-ray mask having a triangular and hollow circle shape pattern. The column array is shaped into the microneedle array by the second inclined exposure without additional mask alignment. Changing the inclined angle and the gap between the mask and polymethylmet-acrylate (positive photoresist) substrate, different types of microneedle arrays are fabricated. We also investigated a novel fabrication method for 3D micro HAR (High Aspect Ratio) structure, the out-of-plane type microneedles which have various shapes at the shanks. The structures are formed by the commonly masked area of the PMMA during three time deep X-ray exposures, which are exposed to the perpendicular direction of the individual face of a cube shape PMMA(5m㎥). By the pre-formed PMMA window after first exposure, successive exposures are self-aligned with deep X-ray mask. The ...