“The potentials are enormous in every environment where organic molecules, germs are potentially harmful, and should be destroyed: water, air, materials surfaces”László Forró
With disposable paper masks being a common way of preventing the spread of the Covid-19 virus, researchers from EPFL in Lausanne have developed a mask that uses a filter “paper” made from titanium oxide nanowires capable of trapping pathogens and using light to destroy them. By eliminating pathogens in this way, the new filter could find uses in personal protective equipment (PPE), as well as air conditioners and air purifiers.
Paper masks are usually made from layers of non-woven polypropylene plastic microfibers, and only trap pathogens but do not destroy them, and their widespread use could be a source of contamination as well as a major environmental problem. As reported in Advanced Functional Materials [Horváth et al. Adv. Funct. Mater. (2020) DOI: 10.1002/adfm.202004615], however, the membrane filter made from titanium oxide nanowires that looks like filter paper but has antibacterial and antiviral properties could be the solution.
The titanium dioxide in the mask is photocatalytic, and upon being exposed to ultraviolet radiation the fibers in the mask convert moisture into oxidizing agents that can destroy pathogens such as viruses and bacteria. The mask is also reusable, with the filter being incorporated in a frame, printable by a 3D printer, so it could be personalized for individual faces. After use, it is placed in a holder, where a UV lamp disinfects the mask in only a couple of minutes, making it clean and totally safe.
The filter is exceptionally good at absorbing moisture, and traps the droplets that carry viruses and bacteria. The team conducted successful experiments showing the membrane's ability to destroy E. coli, the reference bacterium in biomedical research, as well as DNA strands, and hope they can scale up its production. Such masks could also be sterilized and reused up a thousand times, helping combat shortages and substantially reduce the waste from disposable masks. In addition, the manufacturing process ensures they are stable and prevents nanoparticles being inhaled by the wearer.
Their lab can make up to 200 m2 of filter paper in a week, with the potential of producing up to 80,000 masks a month. As team leader László Forró told us, “The potentials are enormous in every environment where organic molecules, germs are potentially harmful, and should be destroyed: water, air, materials surfaces.” They will now work to optimize the filter for specific environments, on its mechanical characteristics, and on “welding” the individual wires into a resistant filter paper before planning production, and are looking for funding to achieve this last step.
Titanium dioxide filter traps pathogens and uses light to destroy them