For centuries, warfighters have used obscurants like smoke to evade enemies and stay safe on the battlefield.

As technology advances and new threats emerge, older capabilities must be modernized to more comprehensively obscure warfighters from enemy sight. As infrared sensors become more widespread, scientists at the U.S. Army Research, Development and Engineering Command Edgewood Chemical Biological Center (RDECOM ECBC) are developing infrared obscurants, which block infrared vision and are disseminated as aerosols on the battlefield.

“As sensor technologies advance, improving smoke to protect and defend the warfighter across the spectrum is more important than ever,” said research chemist Danielle Kuhn, Ph.D. “Those who think of smoke as primitive are missing both the improvements to sensors and obscuration technologies. We are moving smoke into the 21^st century to protect our warfighter.”

“Thermal imaging and infrared sensors are becoming more accessible. You can order night vision goggles on the Internet,” Kuhn said. “Having the infrared sensor technology so readily available motivates our efforts for advanced smokes and obscurants to keep our warfighters safe.”

Infrared sensors and night vision goggles pose a challenge for warfighters. While smoke protects warfighters from the enemy’s naked eye, they may still be exposed to infrared. But by using infrared obscurants, protection is improved.

Infrared obscurants are small aerosol particles that block infrared light, sometimes referred to as heat vision. They can be disseminated through multiple means including grenades, pyrotechnic devices and smoke generators.

“There is an enduring practical need to reduce logistics on the battlefield,” Kuhn said. “With more efficient obscurants, less obscurant is needed to accomplish the mission. This is especially true of infrared obscurants.”

In her search for a high performing infrared obscurant, Kuhn has turned to electrospun conductive nanofibers, which have high theoretical performance due to their electrical conductivity, shape, and size: their diameters are less than 100 nanometers. Produced through a process called electrospinning, nanofibers are also more versatile than flakes, another aerosolized material that helps block infrared.

“Theory tells us that having nanofibers make very good obscurants, and there’s several reasons for that,” Kuhn said. “Nanofibers tend to have high aspect ratios, and if the material is highly conductive and sized appropriately, it will attenuate obscurants in the infrared region.”

Nanofibers are geometrically predisposed to having strong attenuation for infrared.

“You can relate fiber length to the frequency of oscillations of electrons across the surface,” Kuhn said. “So once fiber comes into contact with a source of irradiation, electrons will oscillate across the surface of the fiber at a specific frequency. The frequency of that oscillation can be associated to a specific wavelength.”

In other words, they block infrared light, making the smoke a more effective obscurant. Moreover, they may be able to be used for decontamination purposes.

“Nanofibers are multifunctional in terms of their capabilities,” Kuhn said. “They have catalytic processes for degradation of chemical threats. They can also be used for decontamination purposes.”

Electrospinning, a burgeoning technique that ECBC excels in, is the capability that enables production of nanofibers.

“Electrospinning gives you a platform to make so many different kinds of compositions of nanofibers in different dimensions, so you can create exactly what you’re looking for,” she explained. “You can modify the composition of the fiber. You can functionalize these materials and make other composites. There’s a variety of things you can do.”

Kuhn added that it’s a scalable process.

“If you need to make these materials on a large scale, it is possible,” she said. “When you’re doing research-scale work, you’re working with milligram quantities, which isn’t realistic when you’re talking about fielding a material.”

“This could be used for field materials,” she said. “The sky’s really the limit for what you can do with electrospinning.”