3D print can sense respiratory droplet
As Andy Wang, a Ph.D. student from the University of Cambridge’s Department of Engineering said he used the fiber sensor to test the amount of breath moisture leaked through his face covering, for respiratory conditions such as normal breathing, rapid breathing, and simulated coughing.
These fiber sensors are designed to detect respiratory droplets and moisture from breathing.
This kind of face-covering can have some kind of indicator for protection from COVID.