3D-printed soft robots to mimic creatures living on water

Scientists have developed 3D-printed flexible mesh structures that can be used as soft robots which mimic creatures living on water surfaces or can serve as tissue scaffolds for cell cultures. The flexible mesh structures can be controlled with applied magnetic fields while floating on water, and could grab small objects and carry water droplets, according to the research published in the journal Advanced Materials Technologies.

“This research shows capabilities in the emerging field of combining 3D printing and soft robotics,” said Orlin Velev, a professor at the North Carolina State University in the US.

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.

The researchers used a 3D printer to shape the paste into mesh-like patterns. The patterns are then cured in an oven to create flexible silicone structures that can be controlled—stretched and collapsed—by the application of magnetic fields.

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“This self-reinforced paste allows us to create structures that are ultra-soft and flexible,” said Sangchul Roh, a PhD student at North Carolina State University.

“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, a professor at North Carolina State University.

“The structures are also auxetic, which means that they can expand and contract in all directions. With 3D printing, we can control the shape before and after the application of the magnetic field,” Velev said.

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. “Mimicking live tissues in the body is another possible application for these structures,” Roh said.

The researchers showed how they were able to design reconfigurable meshes, 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. “For now, this is an early stage proof-of-concept for a soft robotic actuator,” Velev said.