N95 Masks Could Be Rechargeable
The pandemic has led to N95 masks quickly becoming one of the world’s most sought-after resources as essential workers burned through billions of them. New research could lead to an N95 that you can recharge rather than throw away — or even one that continuously tops itself up for maximum effectiveness.
The proposed system, from researchers at Technion-IIT in Israel and the Tata Institute of Fundamental Research in India, is not one of decontamination, as you might expect. Instead, it focuses on another aspect of N95 masks that renders them less effective over time.
N95s use both mechanical filtering, in which particles are caught in a matrix of microscopic fibers, and electrostatic filtering, in which particles are attracted to surfaces that carry a static charge. It’s like the old trick where you rub a balloon on your head and it sticks — but at the scale of microns.
The combination of these two methods makes N95 masks very effective, but the electrostatic charge, like any charge, dissipates after time as air and moisture pass over it. While decontamination via UV or high temperature may help keep the mechanical filter from becoming a tiny petri dish, they do nothing to restore the electrostatic charge that acted as a second barrier to entry.
It’s unlikely that healthcare workers are going to be disassembling their masks after every shift, though. While a service and special mask type could (and if it’s effective, should) be established to do this, the team also explored the possibility of a mask with a built-in battery that recharges itself constantly:
A solution that can help replenish the lost charge on the masks in real time would be desirable. In this section, we provide a proof-of-concept method of keeping the masks charged, which comes as a logical extension of our recharging method.
We tested a technique by which the filter material maintains its charge and thus its filtration efficiency… Since the currents required are extremely small, a large battery is not required, and it is possible that a small compact and practical solution may be feasible.