3-D biocompatible microneedle arrays with nanoporous surface

During the past few years, developing painless needles or patches to replace traditional hypodermic needles has been investigated. Since micromachining can be used to construct a high density metallic micropillar array, we propose to use a biocompatible metal oxide, such as Al2O3 and TiO2, as an alternative material for fabricating arrays of microneedles. In this study, we fabricated an anodic aluminum oxide (AAO) covered Al micro-indent array using electrochemical and mechanical micromachining. We demonstrate use of a nanoindenter to make pyramidal indentions on Al surface in order to produce a female microneedle array mold. We also performed melting injection to fill AAO template with ultra-high molecular weight polyethylene (UHMWPE) to produce UHMWPE nanotubes. The microneedle array provides a 3-D structure that possesses several hundred times more surface area than a traditional nanotube template. This suggests that a medical-grade polymer microneedle array can potentially be formed for more applications. This 3-D microneedle array device can be used not only for painless injection or extraction, but also for storage, highly sensitive detection, drug delivery, and microelectrodes.