Detecting molecules in the air is harder than in liquids. That’s why hospitals draw blood, and even at-home COVID tests require adding liquid. One reason is the low concentration. The air may contain only one in a trillion of the particles you want, like viruses. That’s a tough task for a device, and it used to require large, expensive equipment.
Scientists have figured out how to turn air into a liquid so it can be analyzed more easily. Their setup consists of several parts. First, a pump sucks in air. Then a humidifier adds water vapor, and a small cooling system lowers the temperature. This causes the air to turn into droplets, which contain the desired particles. These droplets flow down a smooth surface into a small reservoir. From there, devices can easily measure how many molecules are in the liquid using standard liquid analysis equipment.
When they created the device, the scientists didn’t know whether they would be able to capture certain molecules that evaporate quickly, called “volatiles.” To test the idea, one of the scientists used a cup of coffee. He directed the steam from the coffee into the system to see if it could collect and detect it. When the liquid condensed, it was clear that the experiment had worked—it smelled like coffee.
In subsequent tests, the scientists were able to measure sugar levels in exhaled air, detect E. coli in the air, and look for signs of inflammation in the cells of mice with gut microbiome problems. They called their system ABLE, or “airborne biomarker localization system.”
The technology will be useful in medicine, for example, it will allow non-invasive monitoring of biomarkers and improve care for premature babies.
Scientists have yet to determine which molecules to look for for different tasks. For example, the possibility of detecting signs of inflammatory bowel disease by breathing is currently being studied. There are also plans to make the device smaller and more comfortable to wear. One of the developers expects that this work will help make new discoveries in physics and study how impurities in the air affect physical processes.
