Smart mask converts every breath into a mini health check-up

A new solution to an old problem makes breath analysis in real time possible

The breath we exhale can tell us a lot about our respiratory and metabolic health – like whether we have asthma or if we might be developing kidney disease or need to better manage a case of COPD. But the breath is famously hard to study, especially in real time.

“Typically, analyzing breath involves measuring physical parameters like changes in temperature or rate of breath, which can potentially indicate fever or underlying infections,” said Wei Gao, Ph.D., professor of medical engineering at the California Institute of Technology. “But there’s a lot of information we can analyze at the molecular level.”

The problem is getting to that information – and that’s a problem Gao and his team think they’ve solved. With help from an NHLBI grant, they’ve developed a prototype “smart” facial mask that can do what conventional breath analysis machines cannot: monitor in real time the volatile organic compounds, inorganic substances, and pathogens we exhale as gases.

Breath analysis using these kinds of molecular markers currently can be done only in a clinical setting. “A person needs to breathe into a machine that uses bulky equipment to cool the breath down and condense it into a liquid,” explained Gao. Then the breath sample needs to be sent to a lab for analysis. But because many of the biomarkers change quickly, the information fast becomes dated.

Gao said in developing the smart mask, he and his team were aiming not just for ease, but better results. “We wanted to find a solution to the problem of how to turn the breath to liquid, but also to do it on a wearable sensor to capture the information in real time,” said Gao.

A novel design

The mask basically looks and feels like any common surgical or N-95 face mask – except for tiny, lightweight components packaged in units that are housed inside of the mask. The first of these, the cooling unit, is the centerpiece of the smart design. It makes it possible for the mask to take in a person’s exhaled hot air, chill it, and turn it to liquid – all without needing wires or mechanical parts.

The second unit draws that condensed liquid into the mask through microfluidic capillaries – little channels that transport liquid in much the way a plant brings up water from its root.

The third houses the sensing electrodes, which communicate with a flexible, dime-sized circuit board to identify the specific molecular markers a researcher or doctor might want to see – say, a marker that measures airway inflammation. The data collected from those markers is then transmitted via Bluetooth to a mobile app, allowing users to track changes in the markers over time.

Gao designed the smart mask so it could detect any kind of biomarker. “One electrode on the sensor can analyze one molecular marker selectively, but we can add as many as we want to analyze multiple markers at a time, or they can be switched out,” he said. The good news, he said, is that all the components are flexible and inexpensive to manufacture, costing about $1 in materials for each mask.

Putting it to the test

Gao and his team conducted pilot studies to test the masks under a variety of conditions – while the user is indoors and outdoors, upright and lying down, for example – and in both healthy volunteers and those with conditions such as asthma or COPD.

They found the mask generally comfortable to wear – one healthy volunteer was able to wear it for 14 hours while doing a variety of activities such as exercise, office work, and napping. The researchers envision users wearing it for much shorter stints for certain applications – say, 30 minutes at a time. That’s long enough to give providers the information they need to identify a health problem and offer treatment options.

This potential for using the mask to warn of an emerging health condition or help head off a worsening one could be far-reaching, the researchers believe. So far, the mask has been able to analyze metabolic changes that occurred after volunteers ate and drank, offering insight into whether a person is getting too much protein and how the protein is being digested. In volunteers with asthma and COPD, the mask was able to detect nitrite, a biomarker that signals inflammation in the airways, confirming what could been found through lab tests. The researchers also showed that the masks could be used to monitor kidney disease by accurately detecting higher ammonium levels in the breath – a fallout of increased urea buildup that often comes with kidney function decline. The mask even showed it could accurately measure blood alcohol content after a person drank.

Next steps

Though the pilot studies have shown promise, Gao said his team is conducting larger studies to confirm the mask’s clinical accuracy, while working to scale up manufacturing. If all works out, the impact the smart mask could have on patient health could be significant, said Songtao Liu, Ph.D., a program officer in the advanced technologies and surgeries branch in the Division of Cardiovascular Sciences.

“The real-time feedback allows for more proactive management and early intervention of certain conditions,” he said. “It opens new doors for personalized healthcare in ways that were previously not possible.”