乌鸦传媒

Researchers developed and validated a prototype of a mask-based device designed to continuously monitor exhaled breath condensate (EBC) in pilot studies.

The EBCare mask looks similar to a KF94 mask and employs a self-cooling strategy, an automated microfluidic system, an electrochemical sensor array, and a wireless reading circuit, Wei Gao, PhD, of the California Institute of Technology in Pasadena, and colleagues reported in .

Unlike previous smart masks, EBCare provides real-time monitoring of multiple biomarkers simultaneously.

The "tandem cooling and bioinspired microfluidic design ensure efficient EBC collection and transport, enabling in situ quantitative analysis," Gao told 乌鸦传媒. The mask's "integration of highly selective electrochemical biosensors further enhances its capability to provide detailed molecular insights that were previously inaccessible with other wearable technologies," he added.

EBC is a noninvasive aqueous matrix in which soluble gaseous and nonvolatile biomarkers can be measured. Clinically, it's collected with a commercial condenser or condensation instruments, then analyzed in a lab using mass spectrometry or photometric assays to assess airway inflammation and substance metabolism.

Other EBC capture methods rely on outside refrigeration, which can be difficult to incorporate, but EBCare uses a passive cooling system to effectively chill exhaled breath.

"This research was motivated by the critical need for comprehensive respiratory monitoring, especially in light of recent respiratory pandemics," Gao said.

The researchers validated the EBCare in various real-life settings. Their pilot studies included 31 healthy adults, 12 people newly recovered from COVID-19, 10 smokers, 10 people with asthma, and 9 people with chronic obstructive pulmonary disease (COPD).

Over a span of 14 hours, participants went through both indoor and outdoor activities like exercise, eating, drinking, office work, and napping, wearing the mask the entire time except for 3-minute eating periods.

After breakfast, ammonium concentration slightly decreased and then increased. These levels also rose more substantially after a protein-rich lunch and dinner. Alcohol consumption resulted in a rapid elevation of EBC alcohol concentration, and the levels were comparable to blood alcohol concentration.

Patients with airway inflammation, especially with asthma, had higher nitrite levels than controls (P<0.0001), suggesting that EBC nitrite may help diagnose, monitor, or manage these patients. To demonstrate the clinical significance of EBC nitrite in asthma and other respiratory diseases, the researchers validated the EBCare sensors against fractional exhaled nitric acid (FeNO) and found a strong correlation (r=0.795) between EBC nitrite and FeNO in 31 people.

Elevated EBC ammonium in COPD patients potentially indicated higher serum urea, and a lower EBC pH may be related to airway acidification in asthma patients, the researchers noted.

"EBCare effectively monitors a range of biomarkers, including ammonium, pH, nitrite, and alcohol, across various indoor and outdoor activities," Gao said. This could have implications for monitoring respiratory conditions and metabolic disorders, as well as in respiratory pandemics like COVID. The alcohol metabolism monitoring capabilities could also be used by law enforcement or individuals, he added.

Raed Dweik, MD, chief of the Integrated Hospital Care Institute at the Cleveland Clinic in Ohio, told 乌鸦传媒 that historically, devices to collect EBC have been bulky, so "collecting the breath condensate in a simple way that is reproducible, easy, and portable -- that is novel and exciting."

While there are other ways to measure nitrite, alcohol, ammonia, and pH, Gao and his team demonstrated they can measure these biomarkers in EBC, he noted. "I think the concept that it can be done in a simple and portable way is great, but the things that they measure are not unusual," Dweik said.

It's unclear whether EBCare has an immediate clinical application, Dweik observed, but he sees its potential. Future studies will need to determine whether the device helps in diagnosis, monitoring, and follow-up, and whether it can measure other things, he suggested.

The researchers want to expand EBCare's biomarkers and perform more trials to validate its use in diverse populations and settings, Gao said. They also hope to further develop the device for affordable mass production and explore the possibility of integrated data analytics.

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