Researchers at the University of Texas at Austin have developed a 3D printing method that can create objects with both soft and hard properties in a single print. The technique uses specially formulated resins and different colors of light to control material properties during the printing process.
The method addresses a common problem in multi-material manufacturing where different materials often fail at their connection points. “What really motivated me and my research group is looking at materials in nature,” said Zak Page, an assistant professor of chemistry at the University of Austin and corresponding author. “Nature organically does this in an organic way, combining hard and soft materials without failure at the interface. We wanted to replicate that.”
The printing system uses a custom liquid resin that responds differently to violet and ultraviolet light. Violet light transforms the resin into a soft, rubber-like material, while higher-energy ultraviolet light creates a rigid structure. This dual-light approach allows for seamless transitions between soft and hard zones within a single printed object.
The research team demonstrated the technology by printing a working knee joint with soft ligaments and hard bones that moved smoothly together. They also created a stretchable electronic device with a gold wire, where flexible sections could bend and stretch while stiffer areas protected the circuit from breaking. “Honestly, what surprised me most was how well it worked on the first try. That almost never happens with 3D printing resins,” said a co-author of the study.
The researchers suggest potential applications include prosthetics, flexible medical devices, and stretchable electronics that can move naturally with the body. The process reportedly works faster and offers better resolution than previous approaches while using affordable and relatively simple equipment. The research was published in Nature Materials, with related work appearing in ACS Central Science on May 29.
Source: interestingengineering.com