Innovative Self-Sterilisation Desiccant Masks (SterilMask)

Transmission of COVID-19 occurs through direct, indirect, or close contact with infected people through infected secretions or their respiratory droplets. This can be limited with face masks. Face coverings are now recommended where appropriate social distancing could be difficult to maintain. The protection of frontline health workers is paramount and personal protective equipment (PPE) must be prioritized. However, large numbers of healthcare workers have been infected or lost their lives in spite of using PPEs. Moreover, there is a global shortage of PPE for medical settings, including face masks. Commonly used disposable medical surgical mask and FFP3/N95 mask provide some protection against COVID-19 but are not very effective in high virus concentrations and need to be replaced after each use to avoid contamination.

To address the scarcity of face mask, different approaches have been conceived to disinfect, clean, and sterilise the disposal masks. Since a mask can contain respiratory secretions on both the inside and outside, it is important to effectively decontaminate the mask before reusing it. There are processes in hospitals for cleaning masks, but typically they are time-consuming, involving different types of gases and special machines. Disposable masks are made from non-woven fabrics; FFP3/N95 masks cannot be safely cleaned for reuse since exposure to excessive amounts of water and cleaning products destroys the fibres and damages the carbon filtration systems. Optimum practices for effectively decontaminating masks are still being researched, yet preliminary evidence finds traces of the coronavirus persisted for considerable time on masks, which indicates that continuous sterilisation of face masks is essential for better protection, especially for healthcare facilities.

In this project, a self-sterilising desiccant mask, 'SterilMask' is proposed, which uses highly efficient desiccant material (salts) for continuous sterilisation without damaging the mask's filtration capability and breathability. Instead of using disinfecting materials or additional equipment/tools, SterilMask provides self-sterilisation properties to efficiently decontaminate the mask where the desiccant material kills/deactivates viruses on the mask skin and in the inhaled air. The desiccant material can be encapsulated with porous membrane fabrics to form into a mask. Alternatively, a desiccant sheet made of an impregnated desiccant material onto a membrane sheet layered with a fabric sheet can be used as a mask. Another option is to use the membrane sheet as a cover for SterilMask made from recyclable plastics. The desiccant can humidify inhaled air passing into the nose and sinus cavities, reducing the moisture level/minimising condensation, providing better comfort for wearers. SterilMask can provide long-lasting sterilisation effect. Furthermore, regeneration of the desiccant material/sheet is not needed because the difference in the humidity levels between the inhaled and exhaled air could contribute to the self-balanced performance. An additional filter can be incorporated to SterilMask to enhance breathability, and provide improved comfort for long-period wearers, such as healthcare workers and factory workers.

The advanced and affordable SterilMask will provide safety and enhanced breathing experience, and durability, recyclability, and reusability features. The use of SterilMask would significantly reduce the waste of millions of disposed single-use masks.