Researchers from the University of Illinois at Urbana-Champaign have created a photosensitive ink for 3D printing that can display varying hues across a single object without using traditional dyes. The breakthrough, reported in the Proceedings of the National Academy of Sciences, showcases a material that changes color through light interaction rather than pigment alone, enabling more intricate and multicolored prints in a single build process.
The color effect draws inspiration from the natural nanostructures found on butterfly wings. These tiny architectures manage light by reflecting, scattering, and absorbing wavelengths to produce vivid reds, blues, and greens. By studying how these natural structures manipulate light, engineers have designed a synthetic counterpart that mimics the same optical behavior while remaining compatible with standard 3D printing workflows.
Color control is achieved by exposing the freshly extruded material to ultraviolet light at precise moments. As soon as the material exits the printer’s nozzle, UV exposure triggers changes in the ink that lock in distinct hues. The timing is critical: the material’s microstructure is altered just enough to create stable, color-rich regions without compromising the object’s structural integrity.
Researchers fine-tuned a range of parameters to realize smooth color transitions within a single part. By coordinating extrusion speed, printhead motion, and UV intensity, they managed to produce color zones spanning from deep blue to warm orange. The technique also supports gradient transitions, allowing subtle shading that enhances depth and detail without adding extra materials or post-processing steps.
The work builds on prior efforts to develop ultrathin, durable nano coatings and advanced pigment-free coloring methods. By combining light-responsive chemistry with nanostructured design, the team has opened new possibilities for functional, aesthetically rich 3D printed products that can achieve complex color patterns in a single manufacturing pass without relying on surface painting or dye infiltration. Ongoing research aims to broaden the palette, improve color stability under illumination, and translate the approach to a wider range of printing platforms and materials, with potential applications in consumer electronics, automotive accents, and artistic prototyping. (citation: PNAS)