Insights from BCC Research

Ultra-Thin Graphene Sensor Detects Air Pollution in Homes

Posted by Clayton Luz on Nov 14, 2016 11:00:00 AM

"Sick building syndrome" (SBS) describes situations in which building occupants experience acute health and comfort effects that appear to be linked to time spent in a building, but no specific illness or cause can be identified, according to the Environmental Protection Agency.

 
The complaints may be localized in a particular room or zone, or may be widespread throughout the building. Building occupants complain of symptoms such as cough, chest tightness, fever, chills, and muscle aches. Typically, the symptoms resolve after the complainants leave the building.
 
In addition to sick building syndrome, other conditions such as sick car and sick school syndromes exist.
 
In recent years, there's been an uptick in health problems from low quality air in personal living spaces. But a new graphene-based sensor and switch that detects harmful air pollution may offer preventive help.
 
The sensor detects individual CO2 molecules and volatile organic compound (VOC) gas molecules found in building and interior materials, furniture and even household goods, which an adversely affect our living in modern houses with good insulation.
 
These harmful chemical gases have low concentrations of ppb (parts per billion) levels. But current environmental sensor technology can't detect their hazards because it can only detect concentrations of parts per million (ppm).
 
The graphene-based sensor and switch, developed by scientists from the University of Southampton, in partnership with the Japan Advanced Institute of Science and Technology (JAIST), detects individual CO2 molecules adsorbed onto the suspended graphene.
 
The team applied an electric field though the structure to detect the molecules one by one. By monitoring the electrical resistance of the graphene beam, the adsorption and desorption (whereby a substance is released from or through a surface) processes of individual CO2 molecules onto the graphene were detected as "quantized" changes in resistance (step-wise increase or decrease in resistance).  Within only a few minutes of detection time, a small volume of CO2 gas (equivalent to a concentration of approximately 30 ppb) was released.
 
"In contrast to the commercially available environmental monitoring tools, 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 levels," says Hiroshi Mizuta, a professor at the university.
 
In addition to that discovery, other team members Harold Chong, Marek Schmidt, and Jian Sun have invented graphene-based switches that use novel thin films developed at the University of Southampton. The results of that study were published in the March issue of Nanoscale.
 
The switches, which require remarkably low voltages (below three volts), can be used to power electronic components on demand, greatly improving the battery lifetime of personal electronic devices.
 
Professor Mizuta and the research group are now aiming to bring the two technologies together to create ultra-low-power environmental sensor systems that can detect single molecules.
 
The study was published in Science Advances, the journal of the American Association for the Advancement of Science (AAAS).

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