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Northeastern University in the US improves the precision of inkjet 3D printing through research on water droplet physics.

September 24, 2025 Services 130

Inkjet printers have been around since the late 1980s, but they have advanced by leaps and bounds since their introduction over 30 years ago.

On one hand, they are an engineering marvel: millions of colorful ink droplets are precisely deposited onto a blank sheet of paper, producing everything from written reports to colorful invitations. On the other hand, the opportunities for disruption remain enormous, particularly for more complex printing tasks involving large 3D structures and multiple material types.

Researchers from Northeastern University have achieved a new breakthrough in the field of inkjet printing that could enhance the precision of 3D printing. The research was led by a team under Professor Tang Xiaoyu from the Department of Mechanical and Industrial Engineering, whose work focuses on materials operating at the interface of fluids and solids—directly relevant to the technology inside printers.

Bolstered by a recently received NSF CAREER award, Professor Tang's team is set to develop a new framework to better understand the changing fluid dynamics when particle-laden water droplets fall into liquid. This work could help engineers design more robust and optimized ink processes, as well as more resilient printing hardware.

Fourth-year mechanical engineering students Tang Xiaoyu and Yan Boqian conduct droplet research. Photo by Alyssa Stone/Northeastern University.

The research itself will utilize high-speed cameras capable of capturing 10,000 images per second. Such speed is necessary. "The impact process, from droplet hitting the water surface, will last only less than a hundred milliseconds," Tang Xiaoyu explained.

When analyzing the captured photos and videos, the research team focuses on several key factors: the morphology of the water droplet upon impact, particle distribution, and the velocity field. Tang explained that there is already a wealth of established research documenting the physics produced when water droplets impact a larger body of water. Through this project, the team hopes to explore how these physics change when the droplets are laden with particles such as cornstarch and silica.

"Adding a large number of particles into the liquid makes things more complex, because the viscosity of the liquid is no longer constant, and the mixture can even become solid-like, especially during the droplet impact process," Tang said. "A great example is the 'Oobleck effect'—people can run on a mixture of cornstarch particles in water, but will sink if they stand still."

Tang Xiaoyu. Photo by Alyssa Stone/Northeastern University

This work is directly relevant to 3D printing, as it promises to provide Tang and her team with deeper insights into how different types of materials interact in a more fluid state. "3D printing basically works by depositing droplets onto a substrate, letting them solidify, and building layer by layer," she said. "But sometimes it may not fully solidify, so it remains liquid, and when the next droplet interacts with that liquid, it deforms differently… A lot can happen between the droplet and the uncured layer."

By better understanding these interactions, 3D printer manufacturers will be able to "control the interaction between the droplet and the substrate." The project team also plans to integrate multiple advanced detection techniques to develop a platform upon which other researchers can build and expand.