The new detector is designed to assess air pollution and alert the home owner to dangerous levels. The device works by assessing individual molecules of harmful substances. These substances include a range of volatile organic compounds (VOCs), as well as carbon dioxide. VOCs are organic chemicals that have a high vapor pressure at ordinary room temperature. Respiratory, allergic, or immune effects can occur if excessive amounts are breathed in. At particular risk are infants and children. The type of illnesses that arise include eye, nose, and throat irritation; headaches, loss of coordination, nausea; and damage to the liver, kidney, and central nervous system.
Even low levels of VOCs and carbon dioxide, at the parts per billion level, can cause potential harm and at these low levels the gases are particularly hard to detect. Most current technology, and that which is available for the home, can only detect down to the parts per million level.
Gaseous molecules are adsorbed onto suspended graphene. Graphene is a carbon based material, just one atom thick. The molecules are slowed down and strike the graphene one by one, due to a controlled electric field. Dangerous substances are detected via the monitoring of the electrical resistance of the graphene beam. Different increases and decreases in conductivity indicate different types of airborne pollutants.
The device also has a low power consumption (less than three volts), which gives the battery many years of life.
Speaking with Controlled Environments magazine, lead researcher Professor Hiroshi Mizuta explains the benefits further: “this extreme sensing technology enables us to realize significant miniaturization, resulting in weight and cost reduction in addition to the remarkable improvement in the detection limit from the ppm levels to the ppb [parts per billion] levels.”
The technology was developed at the University of Southampton, who worked alongside the Japan Advanced Institute of Science and Technology (JAIST). The research is published in the journal Science Advances. The paper is titled “Room Temperature Detection of Individual Molecular Physisorption using Suspended Bilayer Graphene.”
