The pandemic of the coronavirus, Covid-19, has reached almost every country on the planet. Due to the huge demand, many countries have already started facing a shortage of face masks, which is currently affecting the health care sectors and medical professionals.
Most commonly used face masks are disposable and intended for one-time use. Referred to as N94 or N95 masks, these are originally made for filtering out up to 95% of fine airborne particles. But they fail to maintain their air filtering function because their electrostatic function disappears when exposed to water – which reduces the filtering efficiency and makes it impossible to reuse them. In response, many companies and researchers are trying to find another, more sustainable solutions.
Recently, a KAIST (Korea Advanced Institute of Science and Technology) research team announced the development of washable and reusable nano-filter for face masks that can fit inside standard surgical masks, which are less scarce. The filters are developed using the proprietary technology that aligns nano-fibers with a diameter of 100~500 nm in orthogonal or unidirectional directions.
The team, led by Professor Il-Doo Kim, used an insulation block electrospinning process to manufacture orthogonal nano-fibers by controlling the alignment of nano-fibers. Unlike existing disposable masks without nano-fibers, the new structure can minimize delivering of the pressure toward the air filter and maximize the filtration efficiency.
According to the researchers, the nano-fiber filtered mask maintained its sturdy frame and excellent filtering efficiency even after being repeatedly washed more than 20 times in ethanol sterilization and wash test. Interestingly, the nano-fiber design was able to successfully filter 94% of contaminants like bacteria even after washing repeatedly. They added that the composition remained unchanged after being soaked in an ethanol solution for more than three hours.
The new filter can be implemented in mid-level KF80 masks, as well as high-level N95 respirators, which are in high demand by healthcare sectors worldwide.
Professor Kim, who focuses on technology that filters fine dust with the help of nano-filters, has already filed this design and now awaiting final approval from the Ministry of Food and Drug Safety to bring his product into the market.
“We believe that this mask can be reusable for about a month even after washing in ethanol. The inner filter can also be replaced,” Professor Kim said in a release. “We found that the mask filters out up to 80 percent of 600-nanometer particles even after undergoing a bending test more than 4,000 times.”
Professor Kim established his startup company, the “Kim Il-Doo Research Institute,” last February that can currently produce 1,500 nano-fiber filters per day.