Scientists at the Donghua University in China have developed a breakthrough process that can turn objects made from thin sheets of graphene into items capable of folding themselves when exposed to infrared light and heat.
In a study featured in the journal Science Advances, Jiuke Mu and his team created two types of materials using graphene oxide (GO).
The first is a material constructed using a reduced version of graphene oxide (rGO) and is inert to molecules of water, while the second one is made from graphene oxide with an attached polymer (GO-PDA) and can readily absorb water.
The researchers then used varying layers of the two compounds to produce a new material that can change shape with or without exposure to water.
When Mu and his colleagues figured out a way to predict the shapes the material can change into, they tried to program it to move in a certain manner.
They did this by changing the amount of water the layers of graphene can absorb using heat and light emitted by an infrared laser. The new material was able to move in different ways such as walking, turning corners and folding.
"Compared with other kinds of self-folding materials, the all-graphene-based structure is simpler, its response behavior is faster and the output is more efficient," Mu explained.
"More importantly, its origami and walking behavior is remotely controlled."
According to the researchers, the breakthrough technology can be used to produce self-folding objects for specific purposes such as tissue engineering, artificial muscle development and creation of remote-controlled robots.
They will now try to create graphene-based objects on a nanoscale in order to discover properties and potential use of self-folding items on such a small scale.
"This work has the appeal of being simple to implement and actuates the films in a reversible manner," Michael Dickey, a researcher on nanomaterial fabrication at the North Carolina State University, said.
"There is interest in materials that can be stored flat and then induced into some useful shape, such as a gripper or an actuator, using simple triggers such as light."
Practical Uses of Graphene-Based Origami Paper
Hongzhi Wang, one of the Donghua researchers who developed the technology, said the new origami-like material can be used to create smart clothing capable of changing its style and shape based on the temperature of the body, changes in the environment and other gentle simulations.
He also plans to integrate the new technology into solar cells to develop self-folding panels.
The ability of the graphene-based origami paper to generate stress close to two orders of magnitude higher compared to skeletal muscles of mammals allows it to be used for the development of artificial muscles.
