New ‘smart’ FFP2 face mask alerts wearers when CO2 limits are exceeded

Scientists and engineers from the University of Granada (UGR) have developed and tested a ‘smart’ FFP2 facemask that notifies the user via their smartphone when the permitted carbon dioxide (CO₂) limits inside the mask are exceeded.

This important scientific advance addresses a problem that has been particularly spotlighted since the COVID-19 pandemic began: that of the CO₂ that we rebreathe inside our facemasks. Wearing FFP2-type facemasks for any length of time produces a concentration of CO₂ between the face and the mask that is higher than the normal atmospheric concentration (~0.04%), due to the gas we exhale when breathing. CO₂ rebreathing can cause adverse health effects, even in healthy people, such as general malaise, headaches, fatigue, shortness of breath, dizziness, sweating, increased heart rate, muscle weakness, and drowsiness

Furthermore, these negative effects are known to be linked to both the duration of exposure and the concentration of the gas itself. For example, some health regulations recommend a maximum value of 0.5% CO₂ in the working environment (averaged over an 8-hour day), or that a 30-minute exposure to 4% CO₂ be considered very harmful to health.

“Since the global pandemic was declared by the World Health Organization due to the spread of COVID-19, the universal use of facemasks has been recommended or imposed among the general population, in a bid to prevent the rapid spread of SARS-CoV-2. Notwithstanding the generalized evidence in favour of facemasks to reduce transmission throughout the population, there is also broad agreement on the possible adverse effects caused by their prolonged use, mainly as a consequence of the increase in respiratory resistance and the re-inhalation of the CO₂ that accumulates inside the mask”, explain the authors of this research.

The new FFP2 facemask designed at the UGR makes it possible to ascertain the level of CO₂ rebreathed in real time, using a smartphone application. This method—a wearable gas-monitoring system that is characterized by its low cost, scalability, reliability, and convenience—represents a significant advance with important health benefits.

This study, published in the prestigious journal Nature Communications, was conducted by the “ECsens” multidisciplinary research team pertaining to the Departments of Analytical Chemistry and Electronics and Computer Technology of the UGR. Together, they developed this wireless, real-time, portable gas-detection system that monitors CO₂ levels inside the FFP2 facemask.

Sensors that measure specific parameters of interest

While standard facemasks simply act as air filters for the nasal and/or mouth passage, the inclusion of sensors to measure specific parameters of interest provides added value that improves their use and effectiveness, creating a new paradigm of ‘smart’ facemasks.

“The system we propose is based on inserting a flexible ‘tag’ into a standard FFP2 mask. This tag comprises an innovative, custom-developed opto-chemical CO₂ sensor, together with the necessary signal-processing electronics. Both the sensor and the circuitry are fabricated onto a lightweight, flexible polymeric substrate, forming the so-called ‘sensing tag’, which causes no discomfort to the wearer”, note the authors. The tag does not require batteries as it is powered wirelessly by the near-field communication (NFC) link—similar to that used for making wireless payments, for example—of a smartphone, using an Android app. This custom-developed app is also used for data processing, alert management, and display and sharing of results.

The UGR scientists have conducted preliminary tests of this ‘smart facemask’ on both subjects conducting sedentary activity and those performing physical exercise. “Our results, which are in line with previous clinical trials, present CO₂ values of between 2% during low-work-rate (sedentary) activities and a peak value of almost 5% during high-intensity physical exercise. These values are significantly higher than the typical range of 0.04%–0.1% of CO₂ found in atmospheric air or in typical work environments that are considered healthy. Although the performance tests we carried out do not constitute a formal clinical trial, they are intended to give an indication of the potential of this system in the field of wearable sensors for non-invasive health monitoring”, the authors explain.

The scientists emphasize that this facemask is 100% environmentally friendly, as it does not require batteries, relying instead on standard wireless smartphone technology.

All of the aforementioned characteristics underline the potential multiple applications of this low-cost device in the fields of non-invasive health monitoring, pre-clinical research, and diagnostics using portable electronic devices. Other sensors can also be included, to detect other gases of interest.

Bibliography

Escobedo, P., Fernández-Ramos, M.D., López-Ruiz, N. et al. (2022) ‘Smart facemask for wireless CO₂ monitoring’, Nat. Commun. 13, 72.

https://doi.org/10.1038/s41467-021-27733-3

https://www.nature.com/articles/s41467-021-27733-3

Nature Portfolio—Behind the Paper: https://engineeringcommunity.nature.com/posts/smart-facemask-for-wireless-carbon-dioxide-monitoring