2020/9/8 11:40:12
Imagine a reusable face mask that protects wearers and those around them from SARS-CoV-2, is comfortable enough to wear all day, and stays in place without frequent adjustment. Based on decades of experience with filtration and textile materials, Georgia Institute of Technology researchers have designed a new mask intended to do just that – and are providing the plans so individuals and manufacturers can make it. The modular Georgia Tech mask combines a barrier filtration material with a stretchable fabric to hold it in place. Prototypes made for testing use hook and eye fasteners on the back of the head to keep the masks on, and include a pocket for an optional filter to increase protection. After 20 washings, the prototypes have not shrunk or lost their shape. "If we want to reopen the economy and ask people to go back to work, we need a mask that is both comfortable and effective," said Sundaresan Jayaraman, the Kolon Professor in Georgia Tech's School of Materials Science and Engineering. "We have taken a science-based approach to designing a better mask, and we are very passionate about getting this out so people can use it to help protect themselves and others from harm."
The fundamental flaw in existing reusable cloth masks is that they – unlike N95 respirators, which are fitted for individual users – leak air around the edges, bypassing their filtration mechanism. That potentially allows virus particles, both large droplets and smaller aerosols, to enter the air breathed in by users, and allows particles from infected persons to exit the mask.
The leakage problem shows up in complaints about eyeglasses fogging up as exhaled breath leaks around the nose, making people less likely to wear them. The fit problem can also be seen in constant adjustments made by wearers, who could potentially contaminate themselves whenever they touch the masks after touching other surfaces.
To address the leakage challenge, Jayaraman and principal research scientist Sungmee Park created a two-part mask that fastens behind the head like many N95 respirators. The front part – the barrier component – contains the filtration material and is contoured to fit tightly while allowing space ahead of the nose and mouth to avoid breathing restrictions and permit unrestricted speech. Made from the kind of moisture-wicking material used in athletic clothing, it includes a pocket into which a filter can be inserted to increase the filtration efficiency and thereby increase protection. The washable fabric filter is made of a blend of Spandex and polyester.
The second part of the mask is fashioned from stretchable material. The stretchable part, which has holes for the ears to help position the mask, holds the front portion in place and fastens with conventional hook and eyelet hardware, a mechanism that has been used in clothing for centuries.
The stretchable part of the mask is made from knitted fabric – a Spandex/Lyocell blend – to allow for stretching around the head and under the chin. The researchers used a woven elastic band sewn with pleats to cover the top of the nose.
The researchers made their mask prototypes from synthetic materials instead of cotton. Though cotton is a natural material, it absorbs moisture and holds it on the face, reducing breathability, and potentially creating a "petri dish" for the growth of microbes.
"Masks have become an essential accessory in our wardrobe and add a social dimension to how we feel about wearing them," Park said. So, the materials chosen for the mask come in a variety of colors and designs. "Integrating form and function is key to having a mask that protects individuals while making them look good and feel less self-conscious," Jayaraman said.
"There is so much misinformation about what face masks can do and cannot do," Jayaraman said. "Being scientists and engineers, we want to put out information backed by science that can help our community reduce the harm from SARS-CoV-2."
(From admin)
Medical-in-China
Balan-Expo
