Multi-material micro stereolithography using multiple droplets of photopolymers for the production of heterogeneous structures

Multi-material 3D printing has attracted much attention due to its ability to produce functional 3D structures. We have developed several types of multi-material micro stereolithography systems including multi-tank type and single cylinder type. Recently, a multi-material micro stereolithography system based on single-photon polymerization using multiple droplets was also developed. In the multi-material micro stereolithography system, several types of photocurable resins are stored on a palette that is moved by a translation stage. Heterogeneous 3D microstructures are formed by accumulating each layer while exchanging the resins. In this system, two cleaning tanks are installed to prevent contamination of resin. Additionally, to prevent inclusion of air bubbles into the 3D-printed parts, the platform supporting the 3D-printed part was moved in horizontal plane. As a result, air bubbles were successfully pushed out of the fabrication area. Using several types of photocurable resins with different colors, multicolor 3D microstructures such as cubes and lattices were fabricated. By adjusting the number of accumulated layers, the color of the 3D-printed structure can be controlled. These multi-material micro stereolithography systems will be useful for producing functional microdevices including microfluidic elements, micromachines and scaffolds.