Dynamic Fluid-Assisted Continuous Multimaterial 3D Printing for Seamless Gradient Structures

Functionally gradient materials emulate nature's ability to seamlessly blend properties through variations in material composition, unlocking advanced engineering applications such as biomedical devices and high-performance composites. Additive manufacturing, particularly stereolithography, enables sophisticated 3D geometries with diverse materials. However, current stereolithography-based multi-material 3D printing is constrained by time-intensive material switching and compromised interfacial properties. To overcome these challenges, we present dynamic fluid-assisted micro continuous liquid interface production (DF-µCLIP), a high-speed multi-material 3D printing platform that integrates varying compositions in a fully continuous fashion. By utilizing the polymerization-free “dead zone”, vliquid resins are seamlessly replenished within a resin bath equipped with dynamic fluidic channels and a synchronized material supply system. DF-µCLIP achieves ultra-fast printing speeds of 90 mm/hour with 7.4 µ m pixel-1 resolution while enabling on-the-fly material transitions. This strategy enhances mechanical strength at multi-material interface through entangled polymer networks and promotes seamless material transitions between distinct materials ilike fragile hydrogels and rigid polymers, addressing interfacial failure caused by mismatch of swelling behavior. Additionally, dynamic material replenishment with real-time composition control enables continuous gradient printing instead of the conventional step-wise controlled gradient. Demonstrations include polymers with gradient color transitions and gradient carbon nanotube (CNT) composites with seamlessly varying conductivity.