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Materials

Light-Activated Soft Material Inches Along

Composite made of a liquid-crystalline polymer and carbon nanotubes might someday put soft robots in motion

by Lauren K. Wolf
March 15, 2013 | APPEARED IN VOLUME 91, ISSUE 11

FUTURE ROBOTS MIGHT BE MADE WITH NEW NANOTUBE-FILLED PLASTIC
Credit: Angew. Chem. Int. Ed./C&EN/YouTube
It used to be that robots conjured visions of metal skeletons and mechanical movements. Today, though, scientists want to make robots from soft materials--ones that are flexible and can handle fragile objects. A research team at the University of Wisconsin, Milwaukee, has now made a carbon nanotube-filled plastic that moves when exposed to infrared light. In this clip, they demonstrate how the potential robotic material can grip and lift objects, and how it can inch up an inclined platform.
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Credit: Angew. Chem. Int. Ed.
When exposed repeatedly to IR light for about two minutes, a hinged strip of nanotube-filled plastic walks an inch up an inclined surface.
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Credit: Angew. Chem. Int. Ed.
When exposed repeatedly to IR light for about two minutes, a hinged strip of nanotube-filled plastic walks an inch up an inclined surface.

Gone are the days when robots were made solely from rigid metal parts and electronic circuitry. Scientists now strive to make flexible, soft, nonmechanical robots that can change shape and delicately handle fragile objects. To help turn that vision into a reality, researchers led by Jian Chen of the University of Wisconsin, Milwaukee, have designed a soft polymeric material that moves when hit with a flash of infrared light (Angew. Chem. Int. Ed., DOI: 10.1002/anie.201210232). The team fabricated the robotic substance by polymerizing and stretching a mixture of acrylate-based liquid-crystal monomers and carbon nanotubes. They attached a sheet of the composite material to the top of a passive layer of silicone. When exposed to IR light, the nanotubes in the liquid crystal-silicone bilayer heat up, causing ordered polymers to undergo a phase transition and become disordered. The motion induces strain that forces the bilayer to bend. To demonstrate the material’s usefulness, the researchers turned a sheet of it into a light-activated gripper that curls around small objects, enabling their transfer from one point to another. The team also added hinges of the polymeric bilayer to a plastic sheet and activated them in sequence to make the whole device walk slowly forward.

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Comments
Inquirer (March 25, 2013 2:16 PM)
Quite interesting, is the composite quite fragile? The Infrared light seemed to be pretty spread out, so would a concentrated laser destroy its integrity?

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