Researchers from The University of Texas at Austin have made significant strides in 3D printing technology, inspired by the resilience found in nature. Their novel method integrates soft and hard materials into a single object, drawing parallels from how nature combines various physical properties, such as the rigidity of bone with the flexibility of cartilage.
This advanced technique, detailed in the journal Nature Materials, aims to revolutionize the production of next-generation prosthetics, flexible medical devices, and stretchable electronics that mimic the natural movements of human joints. Assistant professor Zak Page, leading this research, emphasized the motivation derived from observing how nature achieves seamless integration of materials without failure at contact points.
The study introduces a dual-light printing system that utilizes distinct wavelengths to initiate different chemical reactions within a custom liquid resin. For example, using violet light allows the resin to become stretchy and rubber-like, while higher-energy ultraviolet light solidifies it into a robust form. This enables the fabrication of objects characterized by varying zones of softness and hardness in just one print.
One of the challenges of combining materials with significantly different physical properties is avoiding failure at their interface—something that traditionally occurs due to separation as seen in everyday products like running shoes. The new method solved this by incorporating molecules that enable a strong connection between soft and hard sections with the possibility of a gradual transition.
The researchers showcased this technique by printing a small, functional knee joint comprising flexible ligaments and rigid bone, successfully demonstrating the smooth movement of these components. Additionally, they created a bendable electronic device that incorporates flexible circuitry alongside a stiffer area to maintain functionality without breakage.
Page noted with surprise that their approach worked exceptionally well on the first attempt, highlighting the considerable differences in properties—soft components exhibited rubber-like elasticity while hard sections maintained strength akin to consumer-grade plastics. Their method also promises to be faster and yield higher resolution compared to prior 3D printing techniques, making it accessible to various sectors, including research and healthcare.
This innovative process could open doors for the development of surgical models, wearable sensors, and soft robotics, significantly impacting fields that rely on sophisticated and adaptable technologies. The research was supported by initiatives from the U.S. Department of Defense, the National Science Foundation, and other organizations, and a patent application related to this technology has been filed by the team.