Designed by a team of Korean scientists, the prototype mask incorporates two porous filter membranes – one on either side of the wearer’s face – which are made up of electrospun elastomer nanofibers.

Each disc-shaped membrane is surrounded by and joined to a ring-shaped pneumatic stretching mechanism. That “stretcher” is in turn hooked up to a lightweight portable device that contains an air sensor, an air pump and a microcontroller chip. That device is itself wirelessly linked to an external computer running artificial-intelligence-based software.

When the sensor detects a high concentration of harmful particles in the air, along with a relatively normal rate of respiration on the part of the user, the computer activates the pump. This causes the stretcher ring to inflate and become fatter, which allows the connected membrane to remain in a relaxed state. As a result, the membrane’s pores stay at their smallest, offering the highest degree of filtration.

However, if the sensor detects cleaner air – along with a faster rate of respiration, such as that which might accompany relatively COVID-safe outdoor exercise – the software prompts the stretcher to deflate. It thus gets skinnier, stretching the membrane as it does so. The pore size increases as a result, allowing for easier breathing.

What’s more, tests that were performed on volunteers indicated that even when the pores were large enough to significantly improve the mask’s breathability, its air filtration efficiency dropped by only six percent.

Plans now call for the technology to be made lighter, smaller and less bulky, which could involve doing away with the pump and switching to a non-pneumatic stretching mechanism.

A paper on the research, which is being led by Seung Hwan Ko of Seoul National University, was recently published in the journal ACS Nano.

“Smart” mask auto-adjusts its breathability in response to conditions [New Atlas]