Volumetric Photopolymerization Confinement with Wavelength-selective Photoinitiation and Photoinhibition
Tim Scott, University of Michigan
Abstract: Conventional photolithographic rapid prototyping approaches typically achieve reaction confinement in depth through patterned irradiation of a photopolymerizable resin at a wavelength where the resin strongly absorbs such that only a very thin layer of material is solidified. Consequently, three-dimensional objects are fabricated by progressive, two-dimensional addition of material, curtailing fabrication rates and necessitating the incorporation of support structures to ensure the integrity of overhanging features. Here, we describe the utilization of photo-mediated inhibitors of radical-mediated photopolymerizations to confine in depth the region polymerized in a volume of resin by employing two perpendicular irradiation patterns at wavelengths that independently effect either polymerization initiation or inhibition, enabling facile, three-dimensional photopolymerization patterning in bulk resin and providing a path for greatly increased fabrication rates while obviating the need for overhang supports.