In the fight against novel coronavirus, the researchers have developed a reusable silicone rubber face mask with an N95 filter, which they believe could stop viral particles. According to the study, published in the British Medical Journal Open, the new masks were designed to be easily sterilized and used many times.
The new mask is made of durable silicone rubber and can be manufactured using injection moulding, which is widely used in factories around the world. It requires much less N95 material than a traditional N95 mask.
"One of the key things we recognized early on was that in order to help meet the demand, we needed to really restrict ourselves to methods that could scale," said study researcher Giovanni Traverso from Massachusetts Institute of Technology (MIT) in the US. "We also wanted to maximize the reusability of the system, and we wanted systems that could be sterilized in many different ways," Traverso added.
The researchers decide on silicone rubber -- the material that goes into silicone baking sheets, among other products -- because it is so durable.
Liquid silicone rubber can be easily moulded into any shape using injection moulding, a highly automated process that generates products rapidly. The masks are based on the shape of the 3M 1860 style of N95 masks, the type normally used at Brigham and Women's Hospital.
The researchers tested several different sterilization methods on the silicone masks, including running them through an autoclave (steam sterilizer), putting them in an oven, and soaking them in bleach and in isopropyl alcohol.
Better Fit and Breathability
They found that after sterilization, the silicone material was undamaged. To test the comfort and fit of the masks, the researchers recruited about 20 health care workers from the emergency department and an oncology clinic at Brigham and Women's Hospital.
All 20 participants passed the fit test, and they reported that they were able to successfully insert and remove the N95 filter. When asked their preference between the new mask, a typical N95 mask, and a standard surgical mask, most either said they had no preference or preferred the new silicone mask, the researchers said.
They also gave the new mask high ratings for fit and breathability.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.