Somewhere in the 5th century BCE, Hippocrates accidentally stumbled upon “breathomics”—or the testing of breath for biomarkers— when he tied “sweet smelling” (aka acetone) breath to patients with diabetes, even if he didn’t fully understand the implications of his discovery at the time. In modern times, human breath and fluid have been used as samples for rapid, non-invasive testing of everything from disease to drug and alcohol intoxication.
Hippocrates, though, couldn’t have imagined the technology available to scientists and laypersons today—especially not the fact that 20% of us wear advanced technology on our wrists.
Scientists at Ohio State University have now taken the first step toward turning wearables like smartwatches and finish trackers into the next generation of health monitors. Their new study suggests a wearable sensor may be able to monitor the body’s health by detecting the gases released from a person’s skin.
Most wearable devices are already capable of measuring pulse rate and temperature, and a good amount of research is dedicated to how wearables can take advantage of a person’s perspiration to measure health. Less research has been done on breathomics and biomarkers, although it is still an active area of interest.
Even less research has been done on how biomarkers related to metabolic disorders, like heart disease or diabetes, can be detected from the gases released from skin.
“This is an area of research that hasn’t been nearly as well developed yet because we’re just now producing the technology to measure lower concentrations of these gases with high selectivity,” said Anthony Annerino, lead author of the study and a graduate student in materials science and engineering at The Ohio State University.
In other words, skin-gas biomarker monitoring combines the most attractive features of breath sensing and sweat sensing.
In their study published in PLOS One, the researchers examine the sensitivity and selectivity of a novel chemo-mechanical actuator developed to detect specific gaseous chemicals. The team created a film material made of derivatives of plant cellulose and electroactive polymers. Annerino and his team then placed the film over solutions containing different combinations of ethanol, acetone and water, using machine learning and computational algorithms to accurately record and track the film’s bending response.
According to the study results, the film’s bending showed greater sensitivity to acetone over ethanol. Furthermore, the researchers noted that the film responded significantly faster to acetone. For example, a difference in response time was seen between exposures to solutions 1 and 2, which were pure acetone and pure ethanol, respectively. Then, there was a similarity in response time seen between most exposures to solutions 3 and 4—which both consisted of half acetone, but are alternatively completed by ethanol and water.
“Together, these demonstrate that not only is the sensitivity to acetone greater than the sensitivity to ethanol when considered as pure solvents, but also that the presence of acetone overpowers the response to ethanol so much that responses to solutions 3 and 4 were largely indistinguishable,” the researchers explain in their paper.
The researchers say these findings demonstrate that the films are sensitive enough to track long-term changes in the body, including diabetes (acetone) and liver disease (ethanol).
While more work needs to be done on how the films used in the study would work as actual wearable sensors, the researchers envision the final product being a small device worn on low-sweat body locations, like behind the ear or on the nails. In six months, the scientists hope to have a proof-of-concept, and in a year, they hope to be testing the device on people.
“Discerning health issues through the skin is really the ultimate frontier,” said study co-author Pelagia-Iren Gouma, professor of materials science and engineering. “We are developing a new generation of skin sensors, and it will really be the new norm.”