Researchers have 3D-printed soft mesh robots that reconfigure in magnetic fields and respond to external stimuli by reshaping, an advance with applications in the medical sector and beyond.
Developed at North Carolina State University (NC State), the structures can reportedly grab small objects and carry water droplets, giving them the potential to be useful as soft robots that mimic creatures living 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 Orlin Velev, S. Frank and Doris Culberson Distinguished Professor of Chemical and Biomolecular Engineering at NC State and corresponding author of a paper describing the research.
To create these soft mesh robots, the researchers made an ink from silicone microbeads, bound by liquid silicone and contained in water.
According to NC State, the resulting homocomposite thixotropic paste was then extruded through a 3D printer and formed into mesh-like patterns that are cured in an oven to create flexible silicone structures. These can be controlled - stretched and collapsed - by applying magnetic fields.
Soft mesh robots
"This self-reinforced paste allows us to create structures that are ultra-soft and flexible," said Sangchul Roh, an NC State PhD student in Velev's lab and first author of the paper.
"Embedding of iron carbonyl particles, which are widely available and have a high magnetisation, 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 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."
The structures' properties also allow them to be used while floating on water. "Mimicking live tissues in the body is another possible application for these structures," Roh said.
In the paper, published in a special issue of Advanced Materials Technologies, the researchers showed how they were able to design reconfigurable meshes, a structure that could "grab" a tiny ball of aluminium foil and a structure that can "carry" a single water droplet and then release it on demand through the mesh.
"For now, this is an early stage proof-of-concept for a soft robotic actuator," Velev said.
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