One of graphene’s key properties is its surface area—as a two-dimensional material it really is just all surface. This has advantages in a number of applications, one of which is sensors.
Now researchers at the Electronics and Telecommunications Research Institute and Konkuk University in South Korea have found that if they coat fabrics with graphene, they can detect dangerous gases and alert the wearer of their presence by triggering an LED light.
In research published in Scientific Reports, the Korean researchers coated commercially available yarn with reduced graphene oxide (RGO)—which refers to graphene oxide being stripped of most of its oxide to make graphene—using electrostatic self assembly and molecular glue to produce a bendable and washable electronic textile (e-textile) gas sensor.
“This sensor can bring a significant change to our daily life since it was developed with flexible and widely used fibers, unlike the gas sensors invariably developed with the existing solid substrates,” said Dr. Hyung-Kun Lee, who led this research initiative, in a press release.
The researchers discovered that the graphene-coated yarn was extremely sensitive to nitrogen dioxide, which is produced through the burning of fossil fuels. The sensor operates by the nitrogen oxide molecules changing the electrical resistance of the graphene, which in turn triggers an LED light to turn on.
Within 30 minutes of exposure to 0.25 parts per million of nitrogen dioxide (just under five times above the acceptable standard set by the U.S. Environmental Protection Agency), the sensor detected the toxic gas.
While this fabric-based sensor compares favorably with previous RGO sensors prepared on a flat material, and offers three times the sensitivity to nitrogen oxide, it’s not clear why we would want clothing made from such a fabric. Wearable sensors have all sorts of potentially useful purposes, but this one seems somewhat obscure.
Nonetheless, the research does demonstrate that responsive gas sensors need not be fabricated on a solid substrate.