The durable silicone rubber face mask, developed by MIT researchers, can be manufactured using injection moulding, a process used widely in factories around the world. The mask also includes an N95 filter, but it requires much less N95 material than a traditional N95 mask.

N95 masks are those which meet the US National Institute for Occupational Safety and Health (NIOSH) classification of air filtration, meaning that it filters at least 95 per cent of airborne particles.

Typically, they are not designed to be reused which creates additional waste and can place a strain on limited supplies – such as during the ongoing coronavirus pandemic,” said MIT assistant professor Giovanni Traverso.

“One of the key things we recognised early on was that in order to help meet the demand, we needed to really restrict ourselves to methods that could scale.

“We also wanted to maximise the reusability of the system, and we wanted systems that could be sterilised in many different ways.”

To get around the limited mask supply, many hospitals in recent months have begun sterilising N95 masks with hydrogen peroxide vapour, which can be used up to 20 times on a single mask.

However, this process requires specialised equipment that is not available everywhere, and even with this process, one mask can be worn for only a single day.

Silicone rubber was chosen as the material for the reusable masks due to its high durability and ability to be easily moulded into any shape.

While most of the mask is made of silicone rubber, there is space for one or two N95 filters, which are designed to be replaced after every use, while the rest of the mask can be sterilised and reused.

“With this design, the filters can be popped in and then thrown away after use, and you’re throwing away a lot less material than an N95 mask,” said research engineer Adam Wentworth.

The researchers tested several different sterilisation methods on the silicone masks, including running them through an autoclave (steam steriliser), putting them in an oven, and soaking them in bleach and in isopropyl alcohol. They found that after sterilisation, the silicone material was undamaged.

The researchers are now working on a second version of the mask, which they hope to make more comfortable and durable. They also plan to do additional lab tests measuring the masks’ ability to filter viral particles.