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In today's changing environment, the next threat our nation's
warfighter face may not be on a traditional battlefield. Instead, it
may be a chemical or biological attack without notice.
A new
project funded by the Defense Threat Reduction Agency's Joint
Science and Technology Office and conducted by a team of Lawrence
Livermore National Laboratory (LLNL) scientists have created a new
material that is breathable and protects against biological and
chemical threats. This futuristic material or ‘second skin' will
offer more protection for our warfighters in contaminated
environments by sensing and reacting to chemical and biological
threats.
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September 29, 2016 - A new project funded by the DTRA's Joint
Science and Technology Office and conducted by a team of Lawrence
Livermore National Laboratory (LLNL) scientists have created 'second
skin,' a new material that is breathable and protects against
biological and chemical threats. (Courtesy photo provided by DTRA Chemical and Biological Technologies Department)
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ICurrent protective military uniforms have heavyweight
full-barrier protection or permeable adsorptive protection that
cannot meet the critical demand of simultaneous high comfort and
defense. They also pose a high heat burden to warfighters and do not
react to environmental threats. High breathability is a critical
requirement for protective clothing to prevent heat-stress and
exhaustion when military personnel are engaged in the field.
The JSTO/LLNL ‘second skin' offers a ‘smart' material that
reacts to the environment by blocking chemical agents from
penetrating the warfighter's uniform. “Second skin” blocks harmful
agents such as sulfur mustard (blister agent), GD and VX nerve
agents, toxins such as staphylococcal enterotoxin and biological
spores such as anthrax.
The LLNL team, managed by
Tracee Whitfield from DTRA, fabricated flexible polymeric membranes
with aligned carbon nanotube (CNT) channels as moisture pores. Each
pore is less than five nanometers, 5,000 times smaller than the
width of a human hair. The new composite material provides high
breathability utilizing unique transport properties of these CNT
pores. By quantifying the membrane permeability to water vapor, the
team found for the first time that, when a concentration gradient is
used as a driving force, CNT nanochannels will sustain gas-transport
rates exceeding that of a well-known diffusion theory by more than
one order of magnitude.
These membranes also provide
protection from biological agents due to their minuscule pore size.
Biological threats such as bacteria or viruses are typically larger
than 10 nm, much larger than the LLNL-designed composite material.
Laboratory tests demonstrated the CNT membranes' ability to repel
Dengue virus during filtration tests.
This confirms that
LLNL-developed CNT membranes provide effective protection from
biological threats by size exclusion rather than by preventing
wetting. Furthermore, these results demonstrate that CNT pores
combine high breathability and bio-protection in a single functional
material.
However, chemical agents are much smaller in size
and require the membrane pores react to block the threat. To encode
the membrane with a smart and dynamic reaction to small chemical
hazards, Massachusetts Institute of Technology (MIT) scientists are
modifying these CNT membranes with chemical-threat-responsive
functional groups.
These functional groups will sense and
block the threat like gatekeepers on the pore entrance. Recently,
LLNL and MIT integrated actuating polymers with single walled CNTs
to demonstrate a chemiresistive dosimetric material. These materials
are the foundation of a low cost, passive, wireless hazard badge
that will allow detection of nerve agents.
This spin-off
technology effort was funded within the ‘second skin' project as
basic research; however, plans are underway to develop a wireless
sensor integrated with responsive protective fabrics for the
detection of exposure and material response to chemical warfare
agents. This is a paradigm shift from the concept of a deployable
sensor that is worn as a badge; as LLNL and MIT would embed sensors
in the fabric itself. As the fabric reacts to provide protection,
the physical-chemical change in the fabric can be measured and
analyzed. Swatch evaluations will occur in early 2018 to demonstrate
the concept of ‘second skin,' a major milestone that is a key step
in the maturation of this technology. The new uniforms could be
deployed to the field in less than 10 years.
By Elizabeth Meixler, Defense Threat Reduction Agency
Provided
through DVIDS
Copyright 2016
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