Researchers from the UK’s University of Cambridge (www.cam.ac.uk) say they have created micro-thin fibres that exceed the capabilities of conventional film-based sensors. The new devices were used to test the leakage of common protective masks under a range of breathing conditions.

The 3D-printed composite fibres are comprised of silver, semiconducting polymers, or both materials, the university said, and they were made with a technique that creates a high-purity core with a thin, protective polymer sheath – a structure similar to common electrical cables but only a few micrometres in diameter.

Researchers used the fibre sensor to test the amount of breath moisture leaked through face coverings under respiratory conditions such as normal breathing, rapid breathing, and simulated coughing. The devices were said to significantly outperform comparable commercial sensors, especially in monitoring rapid breathing, which replicates shortness of breath.

The team found that most leakage from fabric or surgical masks comes from the front, especially during coughing, while most leakage from N95 masks occurs at the top and sides with tight fittings, the university said. Nonetheless, both types of face masks, when worn properly, help weaken the flow of exhaled breath.

The team looks to develop this fibre-printing technique for a number of multi-functional sensors, which could potentially detect more breath varieties for mobile health monitoring, or for bio-machine interface applications.