Mosquitoes can bite through clothing, but adding an ultra-thin layer of graphene can make fabric impenetrable. In a new study, researchers from Brown University tested the nanomaterial—which has been used to make everything from efficient solar cells to stronger, lighter drones—to see how well it thwarted insects.
It’s already possible to buy shirts treated with permethrin, a chemical that can incapacitate or kill mosquitoes, though the chemical is a known carcinogen; the EPA says that the amount used in clothing is too low to harm humans, but some consumers still choose to avoid it. The clothing also may not always work—in tests by Consumer Reports, some people wearing the shirts stuck their arms in a mosquito-filled cage and still got bites. Spraying the insect repellent DEET on clothes can also keep insects away, but that chemical—originally developed as a pesticide and then used in jungle warfare—may also have some risks. A small number of cases of brain disease in children were linked to DEET. The researchers saw an opportunity to make a physical barrier with graphene instead. “There’s a desire to avoid some of the environmental and health effects [of alternatives],” says Robert Hurt, an engineering professor at Brown and senior author of a paper about the study.
Graphene is a transparent, very thin material made of a one-atom-thick layer of carbon atoms that can be peeled off graphite, the same material found in pencils. The researchers used a stack of multiple layers of graphene, which can be produced more easily and inexpensively than the thinnest version. “We coat this graphene, little flakes, from a liquid suspension like an ink,” Hurt says. “It dries and forms a graphene film which you can put on fabric or on some kind of backing.”
In tests, the researchers recruited volunteers to cover their arms in cheesecloth lined with graphene film and asked them to stick their arms in a mosquito-filled space. With bare arms, or arms covered with cheesecloth alone, they were covered in bites. With the extra graphene layer, the mosquitoes couldn’t bite, and no longer seemed to be able to get chemical signals from the skin to sense that a snack of blood was nearby.
Of course, someone wearing clothes made from the material would still be vulnerable on areas of skin that aren’t covered. But fabric coated or lined with graphene can be lightweight and comfortable enough that people might be more likely to wear long sleeves or cover their legs. The researchers previously tested another version of the material for clothing that offers chemical protection for workers that deal with toxic chemicals—it’s breathable, so someone wearing it won’t get sweaty, but the chemicals can’t get in.
The research is at an early stage, but the team is interested in testing it further and potentially developing clothing to provide to customers like the military, which currently buys permethrin-treated clothes. Because of the type of graphene used and the small amount of the material, it may not necessarily be expensive (as graphene slowly comes to market, one graphene jacket that currently exists is very pricey; more scale in manufacturing will help). If graphene clothes could be widely used, it could help play a role in public health, since mosquitoes spread diseases from Zika and malaria to Eastern equine encephalitis and West Nile virus.