Smart mask monitors breath for disease

Exhaled breath contains water vapor bearing an array of compounds, including some that indicate diseases. A soft mask that analyzes breath to detect these biomarkers could let people easily monitor health at home (Science 2024, DOI: 10.1126/science.adn6471).

Sensing exhaled molecules typically requires bulky devices to condense the moisture in breath, says Wei Gao, a medical engineer at the California Institute of Technology.

Gao and colleagues created a wearable device that condenses breath using two cooling materials. One is a hydrogel that absorbs heat from breath and brings down temperature as the water in it naturally evaporates. The other is an alumina–polymer material that reflects sunlight and radiates heat into space. A microfluidic module containing hydrophilic channels and tiny pillars siphons the condensed moisture over an electrochemical sensor, which identifies analytes in the fluid, and on to the hydrogel to hydrate it. A small electronic circuit transmits sensor data to a mobile app via Bluetooth.

The mask could analyze breath continuously for 14 h, detecting pH, alcohol, ammonium, and nitrite levels, the latter of which can signify airway inflammation from asthma and other lung diseases. Gao says the sensor could be tailored to spot other diseases such as lung cancer and tuberculosis.

This work is a “tour de force,” says Peter Nguyen, a biochemist at Harvard University. “Essentially, you are wearing a laboratory that is monitoring your breath content.” To be cost effective, the team will need to simplify the system and increase the mask’s longevity, he says.