Nanoparticle Application to Mask Filter23 Nov 2020 16:37
I doubt its ink or printed.
I would postulate that the Cu nanoparticles (being so small they are invisible to the naked eye and still tiny with an electron microscope) are applied to the fabric layer in a nano- mist - and "cling by static" maybe.
Makes sense as it has been used in the description of the "kill mechanism" that the Cu nanoparticles release ions in to the virus rendering it dead instantly.
This Tech is going to be massive IMO
DYOR etc
GLA