Self-folding graphene paper has the potential to be employed in developing tiny robots, and even artificial body parts, Chinese researchers have claimed.
Through a study published on November 6 in the journal Science Advances, experts at Donghua University have shown that they have created an innovative technique which employs infrared light and heat in order to animate graphene sheets.
Two thin layers of pure carbon were required, which measured just one atom in thickness, but were actually incredibly sturdy, with a strength 200 times higher than that of steel.
Scientists resorted to graphene oxide (GO) to make nano-scale components which were assembled into sheets, and afterwards treated some parts of these papers with polydopamine (PDA).
Those areas maintained oxygen when a reduction reaction was carried out, while the untreated portions were depleted of oxygen. Following this, small objects made out of this material acted like origami in motion under the effect of various stimuli.
More precisely, the folds of paper which had reacted with PDA could absorb gaseous water from the environment, and upon being exposed to heat using infrared light, the fabric dehydrated, which made it contract and twist. In contrast, when being cooled, the objects changed their shape once again, by expanding.
The creations could also switch position: they could advance or move backwards, and they could even move in a different direction or turn corners, which is actually unprecedented when it comes to self-folding fabrics.
Traditionally, active polymers have been used for programmable materials, especially in order to create artificial muscles and Braille displays. However, graphene paper is superior because of its stability, affordability and simplicity and also because it’s incredibly stretchy and responsive.
Moreover, its potency persists when the fabric is folded 500 times, and its energy-conversion rate, which is of 1.8%, surpasses the one encountered among electroactive polymers, which has been measured at just 1% or even lower.
According to Jiuke Mu, Ph.D. student at Donghua University and one of the material’s developers, there could be a multitude of applications for this invention in technology and medicine.
For example, researchers could use it in order to create miniature robots steerable through WiFi, or the layers could be employed for building artificial muscles and other tissues.
Smart apparel could also incorporate this type of fabric, which would allow it to alter its structure or shape based on weather conditions, body temperature and other similar factors.
Numerous self-folding objects had already been created in prior experiments, such as humanoid robots that can be enabled to assemble themselves under the effect of heat.
Now, study authors have developed a walking device that can curve, move forward and backward or turn, based on the amount of near-infrared light it receives. Other inventions include a box that can build itself from scratch, or an artificial hand capable of holding things weighing 5 times more than itself.
It is hoped that in the next stage nano-scale objects will be designed, which could have an even wider array of functions.
Image Source: ScienceAdvances