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One of the holy grails of robotics is the creation of artificial muscles. No manmade alternative available today can do all the things that a biological muscle can do, but we are making progress towards that goal.

In one such advance, researchers at Donghua University in Shanghai have developed a material that can mimic some capabilities of a real muscle. To build it, they used derivatives of the much-touted material called graphene oxide.

Jiuke Mu and his colleagues created two types of graphene oxide (GO): a reduced version (rGO) which was inert to water molecules, and a version with a polymer attached to it (GO-PDA) that readily absorbed water. Using different layering of these compounds, they created a material that could change shape based on whether or not it had absorbed water.

Jiuke Mu et al/Science

Once they had the materials, Mu and his colleagues created objects with different amounts of rGO and GO-PDA. These objects could change shape based on the amount of water they had absorbed. Their results have been published in Science Advances.

When the changes in shape became predictable, they “programed” the object to move in a certain way. All they had to do was vary the amount of water absorbed by the many layers, which was easily achieved by using an infrared laser that emitted heat and light. The range of movements included folding, walking and even turning corners.

Jiuke Mu et al/Science

This is not the first self-folding material created, but Mu and his colleagues believe that it is one of the strongest and most flexible. In one experiment, they showed that it could “hold” objects that are nearly five times the material’s own weight.

As with any new material developed in a lab, rGO and GO-PDA will need to undergo rigorous testing before they can be used in real-life applications. If it all works out, graphene’s many promises may finally start becoming a reality.

Akshat Rathi
Senior reporter
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