Scientists at Donghua University in China have found a way to cause tiny (0.8 to 6 centimeter) graphene oxide-based objects to move in specific ways using heat and infrared light. The work was inspired by origami, an art form based on folding paper.
In this work, traditional paper was replaced with two types of graphene sheets infused with hydrogen and oxygen compounds, resulting in graphene oxide and graphene oxide-polydopamine. The former does not react to water but the second does. To create origami type structures, the team infused the latter with water molecules than bonded the two types of sheets together—when heat or light was applied to the second type, it would cause the water molecules to be released, making the paper shrink slightly, which in turn would exert a force that would pull against the second type of sheet. This allowed for the creation of hinges or joints which could be employed on command, which made the objects programmable in a sense.
To demonstrate this concept, the team bonded sheets together in such a way as to cause a box to self-form. Another example was of a sheet that formed into a worm-shaped object that was capable of inching along a surface—the team found they could cause it to turn by heating just one side of it. The third was a claw-like object that was capable of grabbing onto something else and in some instances was able to lift other small objects.
The researchers believe this work could lead to the development of a variety of objects such as remote-controlled robots, tissue engineering or even the development of a type of artificial muscle. For their next project, they want to see if it might be possible to create similar types of objects at a much smaller scale, perhaps down to nanosize.