Researchers at The University of Texas at Austin have developed a groundbreaking 3D printing technique that mimics nature’s ability to combine soft and hard materials seamlessly within a single structure. This innovation opens up exciting possibilities for designers working on next-generation medical devices, wearable electronics, stretchable sensors, and even soft robotics.

Drawing inspiration from biological systems—such as the way cartilage and bone integrate within joints—the team created a dual-light 3D printing method using a custom-designed resin. The process enables the production of single printed objects with both soft, rubber-like zones and stiff, durable regions, connected without structural failure at their interface.

Dual-Light Chemistry for Seamless Integration

The novel approach relies on a liquid resin formulation that responds differently to distinct wavelengths of light. When exposed to violet light, the resin solidifies into a stretchable, elastic material. In contrast, ultraviolet (UV) light triggers a different reaction, creating rigid, high-strength components. This dual-light system allows precise control over material properties within one continuous print.

Crucially, the researchers engineered a molecule containing two reactive groups to ensure the different material phases chemically bond at the interface. This avoids delamination or structural weaknesses—a challenge common in multi-material additive manufacturing.

Prototyping Next-Generation Applications

Demonstrations of the technology include a functional miniature knee joint combining rigid “bone” with flexible “ligaments”, and a prototype stretchable electronic strip with embedded gold wiring. The device maintains structural integrity even when bent or stretched, thanks to the strategic placement of soft and rigid segments.

For designers, this process provides opportunities to rethink how materials interact in products, from customised medical implants and wearable sensors to flexible enclosures and advanced soft robotics. Compared to conventional 3D printing or even injection moulding, this method offers finer control, faster speeds, and the potential for greater production scalability.

Accessible Technology with Broad Potential

Importantly, the printer setup is simple and affordable, making it feasible for research labs, educational institutions, and hospitals. The resolution and speed also outperform earlier approaches, supporting rapid prototyping and more intricate geometries.

For designers prioritising sustainability, the integration of flexible and durable functions in one print could reduce the need for assembly and multiple materials, potentially improving recyclability and reducing waste. While the current resin is synthetic, the platform offers a promising base for future biobased or recyclable material formulations.

As additive manufacturing continues to evolve, this light-tuned, bioinspired strategy underscores the expanding design possibilities in multifunctional, hybrid material systems.

Source & photo: The University of Texas at Austin