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Friday, June 3, 2011

Improved gas masks

Researchers led by Michael Sailor of the University of California, San Diego have found a way to make gas masks safer. The team incorporated carbon nanofiber sensors into the masks that indicate when the masks’ filters are saturated, and thus no longer usable.

Gas masks contain canisters of activated charcoal. As a person breathes through the gas mask, airborne toxins stick to that charcoal, leaving the inhaled air free of contaminants. However, as the charcoal filter becomes saturated, it becomes less effective. Eventually, the filter becomes completely clogged and the mask is useless. In the past, the decision of when to discard a used gas mask was based purely on the number of hours of usage. Depending on where that mask had been, this could mean either continuing to use an ineffective, and thus highly dangerous mask, or throwing away a perfectly good mask.

Sailor’s innovation was to add nanofiber sensors to the filters. These thin fibers (each less than half as wide as a human hair) are assembled into photonic crystals that change color as they absorb toxins.

As Sailor explains,

Because these carbon nanofibers have the same chemical properties as the activated charcoal used in respirators, they have a similar ability to absorb organic pollutants.

People who use gas masks equipped with these sensors can be secure in the knowledge that the nanofibers will indicate when the masks are no longer protective.

Caption: Repeating bands of greater density give this bundle of carbon nanofiber photonic crystals a characteristic color. When the porous fibers absorb chemicals, they change color, making the material a sensitive optical sensor for chemical vapors.

Credit: Timothy Kelly, UCSD Chemistry and Biochemistry