Microfabrication of polymer microneedle arrays using two-photon polymerization.

Three dimensional (3D) printing technology has pushed state-of-the-art manufacturing towards more advanced processing methods through its ability to produce complex computer-designed 3D structures in a wide range of materials. Two-photon polymerization applied to the fabrication of ultraprecise 3D microstructures is one of the various innovative approaches to cutting-edge 3D printing. The integration of an ultrashort pulsed laser source and an appropriate photoresist has made it an attractive candidate for advanced photonics and biomedical applications. This paper presents the development of 3D solid microneedle arrays as a novel transdermal drug delivery system via two-photon polymerization in a single manufacturing step. Through a series of experiments, the best fabrication parameters are identified. Finite element simulations are then performed to investigate the interaction between a single microneedle and human skin. The results of this study highlight the influence of fabrication parameters such as laser power, scanning speed, hatch distance and layer height on the structural resolution and fabrication time of microneedles, as well as human skin deformation caused through application of force to a single polymer microneedle.