Graphene holds plenty of superlative titles in the materials world: it’s the strongest, thinnest and most conductive material on earth. Those traits together mean the thin, one-atom-thick sheets of carbon molecules can be applied in lots of ways. Many scientists are optimistic that graphene will one day enhance—or replace—metals and plastics in our daily lives. Swapping silicon with graphene in electronics can effectively create super batteries. It also shows promise in medicine, it can filter water and it can even take a classic little black dress to the next level.
But can graphene repel mosquitoes? It sure can, researchers show in a new study published in the Proceedings of the National Academy of Sciences.
According to a press release, researchers at Brown University were working on lining fabric with graphene oxide—a type of graphene that can be made into thin nanosheets to coat things—to see if it could block chemical exposures. When they brainstormed other uses for graphene-lined clothing, mosquitoes came to mind. The scientists suspected that the insect’s proboscis wouldn’t be able to penetrate the graphene barrier.
To see if it worked, the team recruited volunteers willing to risk a few bites from Aedes aegypti mosquitoes. Participants put their arm in a mosquito-filled chamber, either with bare skin, skin covered with a thin layer of cheese cloth or skin covered by the graphene coated fabric.
While the bare-skinned and cheese cloth-covered participants got hammered by the mosquitoes, those wearing the graphene fabrics didn’t get a single bite.
The mosquitoes didn’t have enough force to push their needle-like proboscis through the graphene oxide, which protected the volunteers. Not only that but insects wouldn’t even land on the fabric, suggesting something else was going on, explains Cintia Castilho, the study’s lead author and a chemical engineer at Brown University.
“With the graphene, the mosquitoes weren’t even landing on the skin patch—they just didn't seem to care,” she says in a statement. “We had assumed that graphene would be a physical barrier to biting, through puncture resistance, but when we saw these experiments we started to think that it was also a chemical barrier that prevents mosquitoes from sensing that someone is there.”
The team then dabbed a little sweat on the outside of the fabric, which immediately drew in the bloodsuckers. The team suspects that besides offering a physical barrier to the bites, the graphene also blocks the chemical cues coming off of human skin. (That makes sense because mosquitoes can detect sweat; earlier this year, researchers confirmed that some mosquitoes including Aedes aegypti have receptors that detect lactic acid and other components in perspiration.)
The fabric does have some limitations. When graphene oxide is dry, mosquitoes can’t produce enough force to puncture it. When the material gets wet, however, their needle-like mouthparts slip right through.
Another version of graphene oxide with reduced oxygen content (rGO) does provide bug-bite protection when it gets wet, but it loses one of graphene oxide’s best qualities.
“Graphene oxide is breathable, meaning you can sweat through it, while rGO isn’t,” says Robert Hurt, the study’s senior author and an engineer at Brown University. “So our preferred embodiment of this technology would be to find a way to stabilize GO mechanically so that is remains strong when wet. This next step would give us the full benefits of breathability and bite protection.”
It’s unlikely that graphene-lined clothes will make it to market anytime soon. Even though carbon—graphene’s only component—is the fourth most common element in the universe, it is currently very difficult to make in large quantities, report Les Johnson and Joseph E. Meany at The American Scientist. Currently, producing even small amounts involves complex machines and multi-step reactions using dangerous chemicals.
In 2017, researchers at Kansas State found a way to produce graphene using small detonations, a process that may be scalable and other processes look promising as well. But it may take a decade, or several decades, before we’re able to produce enough graphene to revolutionize our computers, lighten our airplanes and make mosquitoes to buzz off.