Shape-changing robots courtesy of PU foam

Shape-changing robots courtesy of PU foam
By Jane Denny, Urethanes Technology International
Posted 17 July 2014
Engineers at Massachusetts Institute of Technology (MIT) in the US have developed a polyurethane-based material which they said could be used to create shape-changing robots for a variety of complex tasks.

Surgical robots for operating inside the body without damaging organs, or shape-changing robots that can squeeze through tight spaces on search and rescue missions, are potential applications the wax and foam phase-changing material could facilitate, said MIT.

Lead researcher Anette Hosoi said the challenge was to create a material that could be soft but also exert a reasonable amount of force on its surroundings.

She said: “You can’t just create a bowl of Jell-O, because if the Jell-O has to manipulate an object it simply deforms without applying significant pressure to the thing it was trying to move.”

Researchers placed polyurethane foam in a bath of melted wax then squeezed the foam to encourage it to soak up the wax, which could be replaced by a stronger material, such as solder.

To study the material’s properties in more detail, the team 3D-printed a second version of the foam lattice structure, allowing them to carefully control the position each of the struts and pores, said the press release.

Running a wire along each of the coated foam struts and applying a current to heat up and melt the surround wax caused the material’s hard outer shell to become a soft, pliable surface.

“This would also repair any damage sustained,” said Hosoi. “This material is self-healing so if you push it too far and fracture the coating, you can heat it and then cool it, and the structure returns to its original configuration.”

The MIT team worked with researchers from the Max Planck Institute, Stony Brook University and Google-owned robotics firm Boston Dynamics as part of the Chemical Robots programme of the government’s Defence Advanced Research Projects Agency.



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