Researchers Grow Graphene at Low Temperatures to Boost Flexible, Wearable Electronics' Capabilities
A new method of growing graphene directly onto substrates could prove key for boosting flexible, wearable, and implantable electronics.
Researchers from Caltech and the Industrial Technology Research Institute (ITRI) have published three related studies, which they hope will give a major boost to flexible and wearable electronics, turning — once again — to the "wonder material" graphene to boost performance.
"Flexible and wearable electronics can be made of soft materials like polymers that can't sustain high temperatures," explains lead author Chen-Hsuan "Steve" Lu of the work he and his team have carried out, which works around the typical need to expose materials to temperatures exceeding 1,000°C (1,832°F) to "grow" graphene. "Our method allows us to grow graphene directly on the substrates at a low temperature, preventing any damage to sensitive materials."
With a scalable approach to growing graphene, a single-atom-thick allotrope of carbon, on otherwise-unsuitable substrates, Lu and colleagues set about applying it to flexible electronics. In testing, the resulting graphene-coated copper structures survived repeated folding over hundreds of thousands of times without damage — and demonstrated improved chemical stability and electrical conductivity too.
"We put just two atomic layers of graphene on top of these thin copper lines," says Nai-Chang Yeh, Caltech physics professor and lab leader, "and saw that they were beautifully unchanged after several months."
In a third study, the researchers looked at using graphene to protect gold structures in implantable biosensors. Using their low-temperature approach, the team grew graphene directly onto gold then exposed it to a solution designed to mimic sweat — showing that the structures could withstand at least a month's exposure at normal human body temperatures, a major gain on untreated gold.
"I wasn't aware of graphene's full potential when I first started working with it," claims Lu. "But then I realized how it can be used in tandem with other materials for so many applications. My roommate [co-author Kuang Ming (Allen) Shang] and I were having a boba tea when we realized we could test whether graphene might protect gold from the corrosive effects of sweat."
The three studies, published in ACS Applied Materials and Interfaces and ACS Applied Nano Materials, are linked from Caltech's news announcement.