ADVANCED MATERIALS & PROCESSES | MARCH 2025 60 3D PRINTSHOP TINY, CHIP-BASED 3D PRINTER Researchers from MIT and the University of Texas at Austin have built the first chip-based 3D printer. The proof-of-concept device consists of a single, millimeter-scale photonic chip that emits reconfigurable beams of light into a well of resin that cures into a solid shape when light strikes it. Researchers envision a system where the photonic chip emits a 3D hologram of visible light, rapidly curing an entire object in a single step. This type of portable 3D printer could have many applications, such as enabling clinicians to create tailor-made medical device components or allowing engineers to make rapid prototypes at a job site. “This system is completely rethinking what a 3D printer is,” says Jelena Notaros, professor at MIT and senior author of a paper about the device which was published in Light: Science and Applications. “It is no longer a big box sitting on a bench in a lab creating objects, but something that is handheld and portable. It is exciting to think about the new applications that could come out of this and how the field of 3D printing could change.” But forming and steering the beam is only half the battle. Interfacing with a novel photocurable resin was a completely different challenge. Researchers from UT Austin worked closely with the MIT group, carefully adjusting chemical combinations and concentrations of specialized resins to zero-in on a formula that provided a long shelf-life and rapid curing. doi.org/10.1038/ s41377-024-01478-2. PRINTING CONCRETE WITHOUT NEED FOR REINFORCERS The use of concrete material in 3D printing has been limited by the need for beams and rebars. To print without those supports, the material must be strong enough to hold itself up without getting stuck in the printer. To address these concerns, researchers at The University of New Mexico have developed what they call self-reinforced ultra- ductile cementitious material. The substance must contain enough fiber to stand firmly on its own while maintaining a viscosity that allows it to pass through the printing nozzle without getting stuck. While it might sound simple, finding the right balance is a complex research challenge. If too little fiber is in the mix, the printed shapes might cave in on themselves. Too much fiber and the material won’t make it very far in the printing process. Testing the viability of the materials requires that they be precisely mixed, measured, and printed. Even after designs are printed in several different shapes and designs, including small structures, prisms, and dog bones, they must be tested for their bending and direct tensile strength. The researchers repeated this process and explored mixes made of many materials and fibers, like polyvinyl alcohol, fly ash, silica fume, and ultra-high molecular weight polyethylene fibers. The resulting patent offers four different mixes with up to 11.9% higher strain capacity. “Because of the incorporation of large quantities of short polymeric fibers in this material, it could hold all of the concrete together when subjected to any bending or tension load,” says Maryam Hojati, assistant professor. “If we use this material at a larger scale, we can minimize the requirement of external reinforcement to the printed concrete structure.” unm.edu. The chip contains an array of 160-nm-thick optical antennas and fits onto a U.S. quarter. Courtesy of S. Corsetti et al./Light: Science and Applications. New materials with high structural viability could offer greater resilience to natural disasters and more automation in construction. Courtesy of University of New Mexico School of Engineering.
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