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Volume 89 Issue 49 | p. 36 | Concentrates
Issue Date: December 5, 2011

Soft Robot Walks

Harvard scientists create floppy, all-polymer crawler capable of navigating obstacles
Department: Science & Technology
News Channels: Materials SCENE, Nano SCENE
Keywords: robotics, soft robots, elastomeric polymers, materials science
Wiggling its limbs and spine, an all-polymer robot moves forward about half an inch in one step; the inset shows which limbs are pressurized (green) and which ones are not (red) during the cycle.
Credit: Proc. Natl. Acad. Sci. USA
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Wiggling its limbs and spine, an all-polymer robot moves forward about half an inch in one step; the inset shows which limbs are pressurized (green) and which ones are not (red) during the cycle.
Credit: Proc. Natl. Acad. Sci. USA
In this clip, a starfish-inspired robot, made from elastomeric polymers, crawls, undulates, and creeps under an obstacle.
Credit: Proc. Natl. Acad. Sci. USA/C&EN

Not all robots must contain heavy metal skeletons and parts such as mechanical joints, according to a research team at Harvard University. Led by George M. Whitesides, the scientists have constructed an all-polymer robot that can crawl and undulate backward and forward, even navigating obstacles (Proc. Natl. Acad. Sci. USA, DOI: 10.1073/pnas.1116564108). Fabricated with soft-lithography techniques used to build microfluidic devices, the robot moves via a series of inflatable chambers embedded between layers of the stretchy commercial elastomer Ecoflex and the more rigid plastic polydimethylsiloxane (C&EN, Feb. 14, page 36). The researchers sequentially inflate the chambers in the arms and spine of the tetrapod robot to propel it along. Because of its flexibility, the 0.9-cm-thick robot is able to pass below a glass plate elevated only 2 cm from a surface. The soft crawler has a number of favorable qualities, including its simple, lightweight design, the researchers say. But other materials will be needed to improve its durability and load-bearing capacity. “Soft robotics,” they write, “may, thus, initially be a field more closely related to materials science and to chemistry than to mechanical engineering.”

 
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