This summer, the University of Texas at Austin published an exciting innovation in 3D printing, which has the potential to revolutionize the next generation of medical devices and flexible electronics. Researchers at the university, funded by the US Department of Defense, the National Science Foundation and the Robert A. Welch Foundation, have developed an innovative method which, inspired by a combination of natural materials such as bone and cartilage, enables hard and soft structures to be seamlessly integrated into a single printed object. This has made it possible to create a fully functional knee joint mini-model from a 3D printer.
The new 3D printing method does not use traditional filament, but a special liquid resin that reacts to two light pulses. Ultraviolet light produces hard, plastic-like sections in the hardening process, while violet light produces elastic, rubber-like areas. In this way, transitions from hard to soft can be achieved within a single component.
The artificial knee joint was the researchers’ first attempt to apply the method in practice.
Chemically cross-linked molecules prevent contact points from breaking or becoming structurally weak. As Zak Page, assistant professor at UT Austin, explains: “We built in a molecule with both reactive groups so our two solidification reactions could ‘talk to each other’ at the interface. That gives us a much stronger connection between the soft and hard parts, and there can be a gradual transition if we want.”
First Applications for UT Austin
In practice, the method has already been tested on a knee joint. The artificial bones of the joint had to remain stable, while the ligaments had to act flexibly. The model was fully functional, which holds great promise for biomechanical implants. In addition, the team developed a stretchable electronic strip in which a gold conductor had to be reliably stretchable – despite harder sections of the ligament – in order to protect the conductor.
According to the authors, the research team’s new method works faster and gives better results than previous methods. What’s more, the printer settings are easy to reproduce and inexpensive to implement, making the technique readily available to researchers, hospitals and teachers. “This approach could make additive manufacturing more competitive for higher-volume production compared with traditional processes like injection molding. Just as important, it opens up new design possibilities,” explains Keldy Mason, a PhD student in Page’s lab.
The revolutionary ability to integrate both biological functionality and robust mechanical properties opens up enormous possibilities – from medical implants to wearable electronics to soft robotics components. Thanks to its high precision, scalability and cost-effectiveness, this approach is on the verge of practical applications for the first time. For more information, click HERE.
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*Photo Credits: UT Austin