Young-Myoung Ha

Insertion Force Estimation of Various Microneedle Array-type Structures Fabricated by a Microstereolithography Apparatus

Microneedles have been fabricated for painless drug delivery via skin. These microneedles have limitations on fabricating and drug amount due to their small size. But the continuous growth of MEMS and LIGA technologies enable fabricating more smaller microneedle, and array-type microneedles can deliver more drug to blood vessels via skin. In this case, the strength against human skin has to be considered according to the shape and arrangement of microneedles. In this paper, instead of MEMS and LIGA technologies, a microstereolithography technology was used to fabricate various microneedle array-type structures. A microstereolithography is a noble process for fabricating complex 3D microstructures with a few micrometers resolution. First, we fabricated three array-type microneedles which shapes are likely to be a quadrangular, but has different dimensions. To analyze fracture force of fabricated microneedle array-type structures, an analysis tool was used. In the analysis the microneedle array was modeled as a quadrangular pyramid with different dimensions which are the same as the fabricated structures. The force acting on microneedle array was distributed load over the whole surface contacted on needle base. Also, to optimize the arrangement of microneedle array, we modeled two microneedles which distance is various. From the result of the analysis, optimal shape, arrangement of microneedle array, and stress acting on the microneedle were found

Fabrication of 3-Dimensional Microstructures Using Dynamic Image Projection

As demand for complex precision parts increase, the existing fabrication methods such as MEMS, and LIGA technology have technical limitations with regard to high precision, high aspect ratio, and high complexity. A microstereolithography technology based on DMDTM(Digital Micromirror Device) can meet these demands. DMD enables a system to handle dynamic patterns. In this technology, the same standard format of the conventional rapid prototyping system, the STL file, is used, and 3D parts are fabricated by stacking layers that are sliced as 2D section from STL file. Whereas in conventional methods, the resin surface is cured by scanning laser beam spot according to the section shape, but in this research, we used an integral process which enabled the resin surface to be cured by one irradiation. In this paper, we dealt with the dynamic pattern generation and DMD operation to fabricate microstructures. Firstly, the microstereolithography apparatus and process were discussed. Secondly, the DMD operation according to mirror tilting, and optimal mounters for DMD and reflecting mirror according to light path were described. And thirdly, complex 3D microstructures were demonstrated.