Lawrence Livermore National Laboratory (LLNL) researchers have developed a novel 3D printing technique that uses light to build complex structures, then cleanly dissolves the support material, expanding possibilities in multi-material additive manufacturing (AM).
In 3D printing, traditional supports often add time, waste and risk to the process, especially when printing intricate parts. But in a new study published in ACS Central Science, an LLNL team - in collaboration with University of California, Santa Barbara (UCSB) researchers - outlines a "one-pot" printing approach that uses two light wavelengths to simultaneously create permanent structures and temporary supports from a single resin formulation.
The method addresses a longstanding challenge in AM: how to fabricate suspended or overhanging features without cumbersome scaffolding requiring manual removal, which is a key hurdle to widespread adoption of Digital Light Processing (DLP) 3D printing technologies.
"This work adds another option to the growing range of multi-material printing possibilities," said principal investigator and LLNL staff researcher Maxim Shusteff. "Using multiple materials is critical to many manufacturing processes, and that's been hard to accomplish using 3D printing. And manually removing supports printed from the same material is one of the bottlenecks preventing the use of DLP in production activities and hurting part accuracy - dissolving a sacrificial material is much more automation-compatible and less cumbersome."
One of the study's key innovations lies in a custom-built, dual-wavelength negative imaging (DWNI) DLP printer, patented by co-author and LLNL engineer Bryan Moran. The system uses a single digital micromirror device to project both ultraviolet (UV) and visible light at the same time, each triggering a different chemical reaction. The UV light solidifies the final epoxy structure, while the visible light cures a degradable thermoset designed to dissolve post-printing.
After thermal postprocessing, the printed objects are placed in a basic water-based solution, where the supports gently dissolve, leaving the primary structure intact with no damage or residue. The team successfully demonstrated free-floating designs including interlocked rings and a ball-in-a-cage - shapes that are difficult or impossible to produce with conventional layer-by-layer methods.
The approach offers practical advantages: reduced print time, minimal material waste and improved resolution. It also avoids the need to swap resins mid-print, a common obstacle in multi-material 3D printing, researchers said.
"Our one-pot embedded printing approach improves the fidelity of unsupported, free-floating structures, such as overhangs and cantilevers, by using degradable supports that act as temporary scaffolds to prevent collapse and misalignment during fabrication," said first author Isabel Arias Ponce, a UC National Laboratory Fees Graduate Scholar and soon-to-be LLNL materials engineer. "Additionally, mobile components - such as hinges and interlocking systems - could be fabricated in place by simply patterning a degradable interface between multiple parts. This would eliminate the need for manual assembly and enhance production efficiency."
The work received funding through the Laboratory Directed Research and Development program and the Lawrence Postdoctoral Fellowship at LLNL. Co-authors include former LLNL Postdoctoral Fellow Sijia Huang, currently an assistant professor at the University of Utah; and Professor Craig Hawker of UCSB.
