Recent respiratory outbreaks have garnered substantial attention, yet most respiratory monitoring remains confined to physical signals. Exhaled breath condensate (EBC) harbors rich molecular information that could unveil diverse insights into an individual’s health. Now, Caltech’s Professor Wei Gao and colleagues have developed the EBCare, a mask-based device for real-time monitoring of EBC biomarkers. For example, the EBCare mask could monitor asthma patients for levels of nitrite, a chemical that indicates airway inflammation.
This schematic shows the process by which the smart mask can detect chemicals in the breath, such as nitrite, which is an indicator of airway inflammation. Image credit: Wei Gao & Wenzheng Heng, Caltech.
“Monitoring a patient’s breath is something that is routinely done, for example, to assess asthma and other respiratory conditions,” Professor Gao said.
“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 personalized 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 analyze the chemicals or molecules in somebody’s breath, it needs to be first cooled and condensed into a liquid
In clinical settings, this cooling step is done separately from the analysis. Moistbreath samples are chilled on buckets of ice or bulky refrigerated coolers.
The EBCare mask, in contrast, is self-cooling, according to the team.
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 analyze the chemical molecules in breath in real time through daily masks,” said Caltech graduate student Wenzheng Heng.
“The breath condensate contains soluble gases as well as nonvolatile 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, belonging to a class of devices referred to as bioinspired microfluidics, immediately transports the liquid to sensors for analysis.
“We learned from plants how to transport the water. Plants use capillary forces to draw water upward from the ground,” Professor Gao said.
“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. It is designed to cost only about $1 in materials.”
To test the masks, the authors 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 experiment, they 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.
At the same time, urea increases in saliva, which breaks down into ammonia gas, and this leads to higher ammonium levels in the breath condensate.
The study showed that the smart masks could accurately detect these ammonium levels, closely reflecting urea levels in the blood.
“The smart mask platform for EBC harvesting and analysis represents a major advance in the potential to monitor lung health in real time,” said Professor Harry Rossiter from the Lundquist Institute for Biomedical Innovation at Harbor-UCLA Medical Center.
“That concept, that biosensors for a wide range of compounds may be added in the future, highlights the game-changing potential of the smart mask for health monitoring and diagnostics.”
The team’s work is described in a paper in the journal Science.
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Wenzheng Heng et al. 2024. A smart mask for exhaled breath condensate harvesting and analysis. Science 385 (6712): 954-961; doi: 10.1126/science.adn6471
This article is a version of a press-release provided by Caltech.
