‘Smart mask’ analyses breath for signs of medical conditions

In contrast to other smart masks being developed that monitor physical changes like the temperature, humidity, or rate of breath, the EBCare smart mask can analyse the chemicals in a person’s breath in real time. In use, the mask could monitor asthma patients for levels of nitrite, a chemical that indicates airway inflammation. The mask is detailed in Science.

Lead researcher, Wei Gao, professor of medical engineering at Caltech, said: "Monitoring a patient's breath is something that is routinely done, for example, to assess asthma and other respiratory conditions. However, this has required the patient to visit a clinic for sample collection, followed by a waiting period for lab results.

"Since COVID-19, people are wearing masks more. We can leverage this increased mask use for remote personalised monitoring to get real-time feedback about our own health in our home or office. For instance, we could use this information to assess how well a medical treatment may be working."

To selectively analyse the chemicals or molecules in somebody's breath, it first needs to be cooled and condensed into a liquid. In clinical settings, this cooling step is done separately from the analysis. Moist breath samples are chilled on buckets of ice or refrigerated coolers.

In Gao's new mask the breath is cooled by a passive cooling system that integrates hydrogel evaporative cooling with radiative cooling to effectively chill the breath on face masks.

"The mask represents a new paradigm for respiratory and metabolic disease management and precise medicine because we can easily get breath specimens and analyse the chemical molecules in breath in real time through daily masks," said Wenzheng Heng, lead author of the study and a graduate student at Caltech. "The breath condensate contains soluble gases as well as non-volatile substances in the form of aerosols or droplets, such as metabolic substances, inflammatory indicators, and pathogens."

Once the breath has been converted into a liquid, a series of capillaries transports the liquid to sensors for analysis.

The results of the analysis are then transmitted wirelessly to a personal phone, tablet, or computer. "The smart mask can be prepared at a relatively low cost," Gao said in a statement. "It is designed to cost only about $1 in materials."

To test the masks, the team performed a set of human studies, primarily focused on patients with asthma or COPD. They specifically monitored the patients' breath for nitrite, a biomarker for inflammation in both conditions. The results showed that the masks accurately detected the biomarker, indicting inflammation in the patients' airways. 

In another study, the team demonstrated that the masks accurately detected blood alcohol levels in human subjects, suggesting the masks could be used for on-site drinking-and-driving checks or other forms of alcohol-consumption monitoring. 

They also looked at how the masks could potentially be used to evaluate blood urea levels in the monitoring and management of kidney disease. As kidney function declines, protein metabolism by-products like urea accumulate in the blood. Simultaneously, urea increases in saliva, which breaks down into ammonia gas, and this leads to higher ammonium levels in the breath condensate. The new study showed that the smart masks could accurately detect these ammonium levels, closely reflecting urea levels in the blood.

"These first studies are a proof of concept," said Gao. "We want to expand this technology to incorporate different markers related to various health conditions. This is a foundation for creating a mask that functions as a versatile general health–monitoring platform."