A team of researchers from Donghua University in China created a new graphene oxide-based paper that self-folds into a box and inches around like an autonomous origami robot. In an article published in the journal Science Advances, the team describes the graphene paper they used and how they enabled it to self-fold into specific shapes.
The researchers used two different one-atom-thick sheets of graphene that were created using hydrogen and oxygen compounds. One sheet was comprised of graphene oxide, while the other was graphene oxide-polydopamine, a material that reacts with water. The team used this water reactivity to create a dual-layer origami paper that had graphene oxide on one side and a graphene oxide-polydopamine infused with water on the other side.
When exposed to light or heat, the water molecules would be released from the graphene oxide-polydopamine layer, causing it to shrink. This shrinkage then would cause the other graphene layer to bend and fold in response. Using the precision application of heat or infrared light, the team could create paper hinges that would fold on command.
To demonstrate this technology, the researchers created several small origami-like objects measuring 0.8 to 6 centimeters. One was a self-folding object that began as a a T-shaped piece of graphene and then turned into a box. There also was a worm-like paper sheet that could slither along a flat surface and a claw-like object that could grab objects and even pick them up.
Researchers believe their self-actuating material can be used in the future to create artificial muscles and self-moving parts for robots. They also plan to scale down the technology and explore nano sized graphene object. These tiny objects are of interest to the team as they expect the properties of the graphene material to change and its folding properties to vary at these much smaller sizes.