Using Cellulose Nanofiber (CNF) to Create Face Coverings with N95 Performance

Background

Given the recent current events revolving around the COVID‑19 pandemic and CDC guidelines, face coverings have become a necessity in public settings. Due to the increasing evidence of the effectiveness of face masks for the stop of the COVID‑19 virus and other germs/bacteria, wearing them has become a societal norm. Currently, the most common face coverings used are the N95 masks and they have certain shortcomings that can be improved upon. N95 filters are efficient because they contain charged fibers that provide electrostatic forces to attract small nanosized particles. This meets the National Institute for Occupational Safety and Health’s (NIOSH) filter efficiency and breathing resistance requirements. However, due to the formation of moisture‑induced salt bridges, these electrostatic forces do not last a long time which limits shelf life and results in the inability to use N95 masks again after washing them. Therefore there is a need for face coverings that can last longer and be re‑used.

Technology

This technology revolves around enhancing any face-covering material with N95 performance by using a combination of aerial spraying and nanocellulose technology. An air atomizing spray nozzle provides air pressure to uniformly apply a CNF barrier layer to the fabric. This layer provides the fabric with the capability of being an effective face mask.The mechanical strength of the CNF layer is increased by chemically cross‑linking the negative COO‑ groups in the CNF layer with a wet‑strength resin. This will allow for the face-covering to be washed without reducing efficiency. The CNF layer also has the characteristic of being able to retain electrostatic charges when re‑used which maintains its effectiveness.

Advantages

Cost‑effective - Face masks that are reusable - Face masks can be washed while having good charge retention - Longer shelf‑life

Application

This technology is an immediate, low‑cost defense when combatting airborne threats. People can apply the CNF layer to their face‑covering via a spray canister or they can insert/attach fabricated CNF membranes to existing face coverings.