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Prof Velev and Colleagues Develop Process to Print 3D Controllable Soft Mesh Robots

Professor Orlin Velev and his colleagues have created a 3D printer process that produces floating flexible mesh structures that can be controlled with magnetic fields. The structures can grab small objects and carry water droplets, giving them the potential to be useful as soft robots that can function on water surfaces, or that can serve as tissue scaffolds for cell cultures.

“This research shows capabilities in the emerging field of combining 3D printing and soft robotics,” said Dr. Velev, the corresponding author of a paper describing the research. In the paper, published in a special issue of Advanced Materials Technologies, the researchers showed how they were able to design a structure that could “grab” a tiny ball of aluminum foil and a structure that can “carry” a single water droplet and then release it on demand through the mesh.

To create these structures, the researchers made an “ink” from silicone microbeads, bound by liquid silicone and contained in water. The resulting “homocomposite thixotropic paste” resembles common toothpaste, which can easily be squeezed out of a tube but then maintains its shape on your toothbrush without dripping. A 3D printer was used to shape the paste into mesh-like patterns.

“Embedding of iron carbonyl particles, which are widely available and have a high magnetization, allows us to impart a strong response to magnetic field gradients,” added Joseph Tracy, professor of materials science and engineering and a senior co-investigator on the project.

The patterns are then cured in an oven to create flexible silicone structures that can be stretched and collapsed by the application of magnetic fields. The structures’ properties also allow them to be used while floating on water, similar to water striders, or insects that skim or hop across water surfaces.

“This self-reinforced paste allows us to create structures that are ultra-soft and flexible,” said Sangchul Roh, a CBE Ph.D. student in Velev’s lab and first author of the paper. “Mimicking live tissues in the body is another possible application for these structures,” Roh said.

“The structures are also auxetic, which means that they can expand and contract in all directions,” Velev said. “With 3D printing, we can control the shape before and after the application of the magnetic field.” “For now, this is an early stage proof-of-concept for a soft robotic actuator.”

The paper is co-authored by NC State graduate students Lilian B. Okello, Jameson P. Hankwitz and Jessica A.-C. Liu, and undergraduate student Nuran Golbasi.

The research is funded by the National Science Foundation under grants CBET-1604116 and CMMI-1663416.

The original version of this article was written by Mick Kulikowski, Director of Strategic Communications and Media Relations in University Communications at NC State.