One big reason there’s a shortage of face masks that can block the spread of the COVID-19 virus is that they’re single-use devices. The exterior may be contaminated and there’s a good chance that keeping the mask and using it again could transmit the infection, particularly when masks are used around known COVID-19 patients. Because the filters inside N95 masks, that are now being widely used by medical professionals, utilize electrostatic activity to trap particles, washing these devices destroys their filtration capabilities.
Engineers at KAIST, one of South Korea’s finest technology institutes, have now developed a washable filtering material that can be used within face masks. It can withstand at least twenty hand-cleaning cycles without losing its ability to trap fine dust particles. The material, placed on appropriately designed face masks with sturdy frames, lets the entire device maintain its original shape through the washes. According to the KAIST researchers, in their tests the mask could continue filtering up to 80% of 600 nanometer-wide particles even after 4,000 bends. Once the mask has been washed enough times to start losing its filtration qualities, the filter material can be swapped out for a new sheet without having to throw out the rest of the mask.
Within the material are nanofibers, with a diameter of between 100 and 500 nanometers, that are arranged perpendicularly to each other via a novel insulation block electrospinning process. This creates a fine mesh that lets air through while blocking very fine particles. Moreover, the material is highly water resistant and so dries out quickly before being used again.
The South Korean Ministry of Food and Drug Safety is currently reviewing the face masks containing the new material in preparation for approval to manufacture them in large quantities.