Researchers at MIT have developed microscopic chemical sensors that can be sprayed as an aerosol mist. Spray-able sensors could someday be used to detect gas leaks, pollution from power plants, volatile organic compounds, and other air and water contaminants. They could also be injected into a person’s bloodstream to monitor its chemical composition – like a blood test that wouldn’t require drawing any blood, or could be taken as nasal spray or swallowed to track digestive health.
Each sensor is made of a polymer chip about 1 micrometer thick and 100 micrometers across (about as wide as a human hair) overlaid with a circuit made with atomically thin semiconducting materials. The circuit includes a photodiode, which converts ambient light into electric current, and a chemical detector made from a two-dimensional material, such as graphene. A number of 2-D materials may be used as detectors that are sensitive to different chemicals. The circuits are grafted onto colloids – extremely tiny insoluble particle or molecules – giving them the colloid’s ability to travel in unique environments due to their ability to remain suspended in a liquid or the air indefinitely.
Currently, sensors are only able to detect certain particles after they have touched a particular chemical, but it is expected that future sensors could emit light signals when in contact with target particles. The research team is also investigating ways to power the circuits without ambient light and to integrate multiple chemical detectors onto a single chip.
The original paper was published in Nature Nanotechnology in July of 2018.