Cornell engineers unveil self-healing, morphing metal

The hybrid material became malleable when heated and regained its strength and rigidity when cooled.

By Brooks Hays

ITHACA, N.Y., March 21 (UPI) -- A new hybrid material promises to bolster the field of soft robotics. The material is part metal, part foam -- its pliability, strength and durability offer the best of both worlds.

The metal-foam compound is rigid when required, but can change shape on the fly and heal itself when damaged.


"It's sort of like us -- we have a skeleton, plus soft muscles and skin," lead researcher Rob Shepherd, an engineering professor at Cornell University, said in a news release. "Unfortunately, that skeleton limits our ability to change shape -- unlike an octopus, which does not have a skeleton."

Shepherd and his research team set out to create a material with the strength and structural integrity of the human skeletal system, but with the adaptability of an octopus.

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"That's what this idea is about, to have a skeleton when you need it, melt it away when you don't, and then reform it," Shepherd said.

To build their hybrid material, the team used Field's metal, a fusible metal alloy with a relatively low melting point of 144 degrees Fahrenheit. To complete the hybridization process, researchers dipped porous silicone foam in the molten metal alloy and then placed it in a vacuum. As the air is sucked from the foam's pores, it's replaced by the metal.


In testing the end results, researchers found the hybrid material became malleable when heated and regained its strength and rigidity when cooled.

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"Sometimes you want a robot, or any machine, to be stiff," explained Shepherd. "But when you make them stiff, they can't morph their shape very well. And to give a soft robot both capabilities, to be able to morph their structure but also to be stiff and bear load, that's what this material does."

The team published their research in the journal Advanced Materials.

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