May 6, 2022 -- We already have smartwatches and fitness trackers that can tell us things about our bodies like how many steps we take a day, how well we sleep at night, and whether our blood pressure is in a healthy range.
Now, scientists are doing experiments to see whether sensors might be added to wearables to tell us even more about our health based on gases released by our skin.
As part of the process of developing such sensors, scientists have done some preliminary lab tests with a film made from derivatives of plant tissue and electroactive plastic compounds. This film can bend when it's exposed to acetone, a gas excreted from skin, researchers report in the journal PLOS One.
When scientists exposed the film to solutions containing water, ethanol, and acetone, they observed that the film bent in response to the chemicals but not the water.
Acetone is a chemical found naturally in plants and trees, and it's also present in the human body from the breakdown of fat, according to the U.S. Agency for Toxic Substances and Disease Registry.
People make more acetone when they're on a low-fat diet, as well as when they're pregnant or have diabetes. Exercise, heavy drinking, and physical trauma can also lead to elevated acetone levels in the body.
"Acetone has been shown to not only be exhaled with breath but to also be emitted through skin gas from accessible skin areas such as the hands, arms, and fingers, which enables easy, non-invasive, and continuous collection of acetone samples," says senior study author Perena Gouma, PhD, an engineering professor at The Ohio State University in Columbus.
Previously, scientists have confirmed that when people exhale higher levels of acetone, or release higher levels of acetone in their skin, they also have higher acetone levels in their blood, Gouma says.
While some research has shown it's possible to measure acetone in human sweat, these sensors require large amounts of perspiration to get accurate readings and can't function as continuous monitors, the researchers say.
The difference with measuring acetone from skin gases is that it requires very little gas to get a reading and can potentially be monitored around the clock to identify changes over time better.
"Discerning health issues through the skin is really the ultimate frontier," Gouma says. "The project still has a couple of years to go. But in 6 months, we should have proof of concept, and in a year, we'd like to have it tested in people."
If all goes well, the goal would be to make sensors from this film that can be added to wearable devices, the study team says. It could work in smartwatches or fitness trackers, or in special devices worn on low-sweat parts of the body like behind the ear or on the fingernails.
While this idea has some potential, any device people can wear outside of clinical trials is likely a long way off, says Shalini Prasad, PhD, a professor and head of the bioengineering department at the University of Texas, Dallas, who wasn't involved in the new study.
If human trials firmly establish a link between levels of chemicals released by the skin and levels of these chemicals circulating in the body, then there might one day be an opportunity to test skin gases to identify biomarkers for specific diseases, Prasad says.