A team of researchers from the University of California, San Diego, United States, and Tyco Electronics, has developed a new kind of sensor that could warn emergency workers when the carbon filters they wear as protection have become dangerously saturated. First responders protect themselves from volatile organic compounds by breathing through a canister filled with activated charcoal. The toxins stick to the carbon in the filter and become trapped, but as the filters become saturated, the toxins will begin to pass though. Determining when a filter has been spent, however, is difficult, and is usually based on how long the user has worn the mask. The research team assembled nanofibers into repeating structures called photonic crystals that reflect specific wavelengths of light. The sensors change color when the fibers absorb toxins, resulting in a visible indication of their capacity for absorbing additional chemicals. Team leader Michael Sailor, a professor of chemistry and biochemistry and bioengineering, said, “The new sensors would provide a more accurate reading of how much material the carbon in the filters has actually absorbed. 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.” The team’s findings were published in the journal Advanced Materials.
http://www.sciencedaily.com/releases/2011/05/110501183923.htm