Interfaces play a vital role in both natural and engineered systems, significantly influencing vital biological, ecological, and technological characteristics that enhance performance, functionality, and user experience.
However, achieving accurate control over interfaces presents considerable challenges in both conventional and additive manufacturing. The limitations in scalability often obstruct the precise deposition of quasi-2D layers within 3D structures.
At Johns Hopkins University, civil and systems engineers have turned a long-standing challenge in 3D printing into a groundbreaking advantage. Their innovative printing technique effectively addresses the inherent weaknesses that occur at the layer interfaces during 3D printing. This transformative work offers the exciting potential to tailor the behavior of 3D-printed objects, paving the way for unprecedented customization and performance.
“In 3D printing, interfaces are notorious for creating vulnerabilities,” said Jochen Mueller, an assistant professor at Whiting School of Engineering’s Department of Civil and Systems Engineering. “The printed material either adheres too much or too little, resulting in structural weaknesses. It’s similar to the way spaghetti sticks together after cooking but easily pulls apart. This creates flaws that limit the functionality of 3D-printed products.”
To address this issue, the team members created a novel printing method that enables precise control over the interfaces between voxels, the three-dimensional equivalents of pixels, as well as their functionality, including factors like adhesion—how effectively different layers or materials bond with one another.
Referred to as voxel interface 3D printing, or VI3DP, this technique employs a printhead that consists of a standard nozzle surrounded by four additional nozzles.
While the primary nozzle dispenses material, these supplementary nozzles apply a thin layer of different material on top. This capability allows customization and control over the interfaces of each 3D printed line in both single and multi-material printing, thus removing the need for multiple printheads and avoiding unnecessary gaps or features in the printed object.
In addition to producing stronger prints, VI3DP paves the way for a variety of new uses for 3D-printed items. The study highlights how the team can incorporate optical, mechanical, and electrical characteristics into the interfaces—all in a single print while maintaining consistent weight, duration, or cost.
“Adding mechanical, optical, or electrical properties is already possible using some 3D printing processes, including material extrusion and material jetting, but those processes require the properties to be added as entire voxels, rather than thin interfaces surrounding the voxels, significantly reducing throughput and resolution,” Doctoral candidate Daniel Ames said. “Our method makes these properties feasible at a fraction of the voxel size, expanding the range and type of applications for soft materials.”
According to the researchers, the new technology offers an unprecedented level of functional control in 3D printing by integrating interfaces with physical characteristics.
“Interfaces are extremely crucial because of what they can enable,” said Mueller, the corresponding study author. “VI3DP has the potential to produce thinner interfaces, new material combinations, and integrated functions like complex 3D circuits, electromechanical devices, data-embedded composite structures, and print-in-place mechanisms with precise fittings.”
The team plans to explore these possible enhancements in their upcoming studies.
“VI3DP is a strong foundation for future fabrication developments. We’ll be able to print complex structures that have never been possible before,” said Ames.
Journal reference:
- Daniel C. Ames, Sarah Propst, Aadarsh Shah, Jochen Mueller. Voxel Interface Control in Multimaterial Extrusion 3D Printing. Advanced Materials, 2024; DOI: 10.1002/adma.202407599