NFC-Powered "Smart" Face Mask Monitors Carbon Dioxide Levels, Links to a Smartphone App
Designed around fears of carbon dioxide rebreathing, this low-cost sensor keeps you informed on CO₂ levels in your face mask.
A team of scientists and engineers at the University of Granada (UGR) have developed a "smart" filtering face mask, designed to warn the wearer if excessive carbon dioxide rebreathing is taking place.
"Since the global pandemic declaration by the WHO [World Health Organization] due to the spread of COVID-19," the team explains, "the universal use of face masks has been widely recommended or even mandatory in many public or workspaces for a large number of individuals and long durations as a means of source control. Therefore, the integration of sensors in conventional face masks to monitor human physiological and behavioral signals can open new pathways in the field of wearable healthcare device."
The particular aspect chosen for this work: Concerns over carbon dioxide rebreathing, whereby wearing a mask for a long time results in the small amounts of exhaled breath captured within being breathed back in and potentially building up carbon dioxide in the wearer's blood.
"Even though in healthy populations, the potentially life-saving benefits of wearing face masks seem to outweigh the documented adverse effects," the team notes, "there seems to be widespread agreement on the increased breathing resistance, CO₂ rebreathing and decreased inhaled O₂ concentration caused by the use of face masks. In any case, the potential negative effects of CO₂ are known to be related to the duration of exposure, apart from the gas concentration itself."
To strike a balance between the benefits of the mask and concerns over rebreathing, the team set about upgrading an off-the-shelf FFP2-standard filter mask with some smarts. A flexible sensor tag, featuring a custom-designed optochemical carbon dioxide sensor, is fitted within the mask using a polymeric substrate designed for comfort. A near-field communication (NFC) link is used to both power the sensor and to transmit data to a smartphone, which then warns the user if excessive carbon dioxide is detected.
The sensor, which does not require a battery, is stated to offer an eight-hour lifetime — "comparable with recommended FFP2 face mask usage times," the team notes. While the results confirmed the sensor's ability to detect CO₂ within the mask from the user's exhalations, no attempt was made to link in-mask levels with CO₂ or O₂ blood concentrations.
The team's work has been published under open-access terms in the journal Nature Communications.