Although few things are more critical to life than the air we breathe, that air is increasingly filled with pollutants that are detrimental to both the environment and humans. And while terrorists have commonly used explosives to inflict their damage, they increasingly are turning to biological or chemical agents to attack airborne systems, drinking water, and public transportation systems.
In response to such threats, researchers at
RTI International in
Research Triangle Park, North Carolina, are developing methods of using nanotechnology to alleviate both the potentially harmful effects of airborne pollutants as well as terrorist attacks. RTI’s focus on nanotechnology combines and coordinates years of successful work in several
advanced technologies, such as thermoelectrics, materials science and engineering, and filtration and aerosol technology.
Nanotechnology entails the creation of materials, components, devices, and systems at the near-atomic, or
nanoscale, which is a world much smaller than the mere miniaturization of current objects. It involves working with particles in the range of one billionth to 100 billionths of a meter in size, about 1/100,000 the thickness of a human hair.
At this level, precisely arranged atoms and molecules of various materials have different properties than in their larger counterparts. By drawing on fields such as physics, chemistry, materials science, and engineering, nanotechnology allows for the creation of novel materials and products with desired properties such as increased strength, higher surface area, or better conductivity.
According to Lynn Davis, a researcher at RTI, “the air filters found in household ventilation systems are a good example of the potential benefits of nanotechnology for the environment.” Protecting indoor air quality requires filtration of bacteria, smoke, dust, and other airborne particulate and gaseous contaminants. “Improving the efficiency of indoor air filters can help mitigate the health effects of air pollutants and improve indoor air quality,” says Davis.
Research conducted at the nanoscale is improving air filters used in homes and in respirators by increasing the filtering efficiency for removing airborne particulates.
Nanostructures, such as RTI’s
nanofibers, with a small size, light weight, and high surface-to-volume ratio, can effectively trap smaller particles than conventional filters.
The small size of these nanofibers is also advantageous in that they offer less resistance to air flow than do the larger materials commonly used in constructing filters for
HVAC systems and respirators. Hence, less energy is required to push air through the filter and the filter can operate with a lower pressure drop.
RTI researchers have discovered a method of reducing the nanofiber size while maintaining suitable structure and support for the filter. This breakthrough could benefit not only individuals breathing cleaner air at their homes, schools, and offices, but also individuals working in harsh environments wearing a respirator filter made from nanofibers. For example, a firefighter equipped with a respirator containing a nanofiber filter could breathe more easily and hence tire less quickly than with conventional respirators.
Several industries are beginning to exploit the novel properties of nanofibers, which exhibit a smaller size combined with greater strength, elasticity, and surface area. And many researchers consider nanofibers to be the ideal building blocks that can enable devices to perform unique new functions. For example, protective clothing and collective protection systems used to clean up contaminated sites generally use a fibrous type of filter to remove unwanted agents.
According to Davis, “a focus at RTI has been on investigating ‘functionalized nanofibers,’ including novel structures and nanocomposites that could revolutionize the field of air filtration.” RTI’s efforts have made significant progress toward developing these novel applications that will one day help protect people from exposure to harmful dust, bacteria, and other particles, and at the same time reduce energy consumption and pollution to our
environment.
The use of nanoscale sensors for biological and chemical threats can also significantly improve national security programs and emergency response team safety by providing sensitive, selective, and inexpensive sensors that can function in a variety of settings.
For example, RTI is providing
homeland security support that includes reviewing environmental safeguards at potentially targeted industrial facilities, surveying public health system readiness, testing protective military clothing for aerosol penetration, and developing simulation-based training applications to prepare medical personnel for potential attacks.
RTI is developing a nanotechnology-based device called an “
electronic nose,” which would potentially enable a portable device to detect chemical and biological agents. “This very small device could potentially be embedded in the fibers of clothing to measure an individual’s exposure to these environmental contaminants,” according to Davis. This “electronic nose” may improve the capability to detect agents with sensitivity even as small as a single particle of an agent.
Potential electronic nose applications. Image courtesy of NASA.
And because selectivity is no less important than sensitivity, this new technology will aide in molecular recognition, or the ability to distinguish an element in the air that is harmful from one that is not. Altogether, this technology will be able to protect through the filtration, adsorption, destructive adsorption, or neutralization of these harmful agents.
By consolidating and coordinating years of successful work in advanced technologies, RTI is helping to realize nanotechnology’s potential to improve air filtration, prevent pollution, and protect people from the threat of biological and chemical agents. These advances are necessary in today’s world, as the threat of terrorism remains constant and our atmosphere is perpetually changing.
By Terezina Johnson
