Lets get to the science.
How it Works
How it Works
We know from common experience, especially in cold climates with low ambient humidity, that when two fabrics rub against each other they gain static electricity — a phenomenon commonly known as triboelectric charging. Fabrics woven from natural fibers like wool or cotton, which possess higher roughness, and even synthetic fabrics like Nylon gain static charge from rubbing.
The idea of exploiting charged fabrics to aid in filtration goes back a few decades (e.g. please see a brief review by Edward R. Frederick (1974) Some Effects of Electrostatic Charges In Fabric Filtration, Journal of Air Pollution Control Association, 23. 1164. DOI: 10.1080/00022470.1974.10470030), and indeed some early face mask designs incorporating electrocharged filtration did use wool or felt fibers. Over time though, electrospun polymer fabrics have become the mainstay material for the electrocharged layers in face mask designs.
The electrospun polymer material is manufactured using a method called electrospinning — a widely used platform for generating polymer nanofibers. In this method, molten polymer of high viscosity is forced out of tiny orifices. The metallic container (we will call it the emitter) with the orifices holding the polymer melt is positively charged and a flat plate or drum placed at a distance is negatively charged (we will call this the collector).
As the molten polymer is forced out of the emitter’s orifice, the positively charged polymer melt shoots out and is attracted towards the negatively charged collector, and rapidly cools down over the distance covered between the emitter and collector, thereby resulting in polymer nanofibers that are electrically charged.