Graphene sensor detects individual molecules to warn of indoor air pollution

The graphene-based sensor, developed by researchers at Southampton University in collaboration with the Japan Advanced Institute of Science and Technology (JAIST), can detect individual carbon dioxide (CO2) molecules and volatile organic compound (VOC) gas molecules.

These chemicals, which can be found in low concentrations of parts per billion (ppb) in materials, furniture and household goods in homes, offices, schools and cars, are believed to contribute to health problems associated with so-called sick building syndrome.

These pollutants are extremely difficult to detect with existing sensors, which can only detect gases with concentrations of parts per million.

The sensor, developed by a group led by Prof Hiroshi Mizuta, who has a joint appointment at both Southampton University and JAIST, can detect a single CO2 molecule as it bonds to the graphene – a process known as adsorption.

The sensor, presented in a paper in the journal Science Advances, consists of a 300 nanometre-long graphene beam suspended above a gold electrode formed on a silicon substrate, according to Mizuta. As a gas molecule is adsorbed onto the graphene, it alters the electrical resistance of the material to a detectable degree, he said.