In the age of SARS, what the world needs is a better respirator, or breathing mask. As hospitals worldwide face major shortages of masks, Da-Ren Chen, Ph.D., assistant professor of mechanical engineering at Washington University in St. Louis, has developed material for a breathing mask, creating a polymer recipe of nanofibers so tiny and skinny that the entry of harmful particles as minute as viruses and bacteria is nearly impossible.
The mask is comprised of just less than two percent material, more than 98 percent air. Thus, it is inexpensive to mass-produce, allowing companies a good profit opportunity. Because it is constructed of such tiny nanofibers, it is far more comfortable to wear than commercial masks.
“What we’ve done is to improve the particle collection ability while reducing the pressure drop that occurs when air molecules hit the mask fiber surface, which is what makes people uncomfortable,” said Chen, a member of Washington University’s Environmental Engineering Science Program.
Ninety percent of respirators or masks made today are made of glass fibers, which are under fire by some critics as posing health problems. Chen’s material is a synthetic polymer. Current masks or respirators are made of fibers as small as 500 nanometers, but Chen’s are made in the 20 to 30-nanometer range.
The tiny size of the fiber material is important because bacteria are actually in the micrometer size range. One micrometer is one-millionth of a meter (a meter is approximately one yard); one nanometer is approximately one-billionth of a yard. A nanometer is one-thousandth of a micrometer; in comparison, a strand of human hair is typically 50 to 100 micrometers thick.
Yet, viruses are even smaller creatures, most of them are in the nanometer size range. Thus, Chen is shooting for material in the 20-nanometer range.