Indoor Air Pollution

Air pollution is a common nuisance when going outside, especially if you live in a major city. But what receives far less concern is indoor pollution, which can be extremely harmful to human health. Especially in recent years, indoor air pollution has been more of a concern and has led to sick building syndrome (SBS), sick car syndrome, and sick school syndrome.

To counteract this problem, scientists from the University of Southampton and the Japan Advanced Institute of Science and Technology (JAIST) created a lightweight sensor that can detect indoor air pollution.

The sensor and switch are made from graphene, a material that's one-atom thick and super durable. The entire device operates using very little power consumption. Their research is published in the journal Science Advances.

Schematic of the single-molecule sensor detecting CO2, with the signal shown on the simulated monitor screen. Source: University of Southampton

The sensor works by detecting volatile organic compounds (VOCs) and individual CO2 molecules that are lingering indoors. They're commonly found in building materials and household goods. Over time, they can harm your health even if your home has good insulation.

Improving the Technology

Because CO2 and VOCs are found in extremely minuscule concentrations (parts per billions), they're very hard to detect with technology that's only adapted to parts per million.

In response to this issue, the researcher's sensor detects these individual particles in the parts per billion level, once they are absorbed onto the graphene layer. There is an electric field charged throughout the structure that detects the molecules one by one.

The team conducted an experiment using the sensor and detected approximately 30 ppb of CO2 gas molecules in only a few minutes. "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," stated Professor Hiroshi Mizuta, a researcher involved in the study.

Two other scientists involved in the research developed a graphene-based switch that uses less than three volts of power. It's energy-efficient and could greatly improve the battery life of handheld electronic devices.

The research team believes that if they can integrate both inventions together—the switch and the sensor—then they'll be able to create a super low-powered environmental sensor that works at similar efficiency.

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