Tag Archives: Dynamic Multifunctional Material for a Second Skin Program

Protecting soldiers from biological and chemical agents with a ‘second skin’ made of carbon nanotubes

There are lots of ‘second skins’ which promise to protect against various chemical and biological agents, the big plus for this ‘skin’ from the US Lawrence Livermore National Laboratory is breathability. From an Aug. 3, 2016 news item on Nanowerk (Note: A link has been removed),

This material is the first key component of futuristic smart uniforms that also will respond to and protect from environmental chemical hazards. The research appears in the July 27 [2016] edition of the journal, , Advanced Materials (“Carbon Nanotubes: Ultrabreathable and Protective Membranes with Sub-5 nm Carbon Nanotube Pores”).

An Aug. 3, 2016 Lawrence Livermore National Laboratory (LLNL) news release (also on EurekAlert), which originated the news item, explains further (Note: Links have been removed),

High breathability is a critical requirement for protective clothing to prevent heat-stress and exhaustion when military personnel are engaged in missions in contaminated environments. Current protective military uniforms are based on heavyweight full-barrier protection or permeable adsorptive protective garments that cannot meet the critical demand of simultaneous high comfort and protection, and provide a passive rather than active response to an environmental threat.

The LLNL team fabricated flexible polymeric membranes with aligned carbon nanotube (CNT) channels as moisture conductive pores. The size of these pores (less than 5 nanometers, nm) is 5,000 times smaller than the width of a human hair [if 1 nm is 1/100,000 or 1/60,000 of a human hair {the two most commonly used measurements} then wouldn’t 5 nm be between 1/20,000 or1/15,000 of a human hair?] .

“We demonstrated that these membranes provide rates of water vapor transport that surpass those of commercial breathable fabrics like GoreTex, even though the CNT pores are only a few nanometers wide,” said Ngoc Bui, the lead author of the paper.

To provide high breathability, the new composite material takes advantage of the unique transport properties of carbon nanotube 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 can 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 very small pore size — less than 5 nanometers (nm) wide. Biological threats like bacteria or viruses are much larger and typically more than 10-nm in size. Performed tests demonstrated that the CNT membranes repelled Dengue virus from aqueous solutions during filtration tests. This confirms that LLNL-developed CNT membranes provide effective protection from biological threats by size exclusion rather than by merely preventing wetting.

Furthermore, the results show 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 to be able to react to block the threat. To encode the membrane with a smart and dynamic response to small chemical hazards, LLNL scientists and collaborators are surface modifying these prototype carbon nanotube membranes with chemical-threat-responsive functional groups. These functional groups will sense and block the threat like gatekeepers on the pore entrance. A second response scheme also is in development — similar to how living skin peels off when challenged with dangerous external factors. The fabric will exfoliate upon reaction with the chemical agent.

“The material will be like a smart second skin that responds to the environment,” said Kuang Jen Wu, leader of LLNL’s Biosecurity & Biosciences Group. “In this way, the fabric will be able to block chemical agents such as sulfur mustard (blister agent), GD and VX nerve agents, toxins such as staphylococcal enterotoxin and biological spores such as anthrax.”

Current work is directed toward designing this multifunctional material to undergo a rapid transition from the breathable state to the protective state.

“These responsive membranes are expected to be particularly effective in mitigating a physiological burden because a less breathable but protective state can be actuated locally and only when needed,” said Francesco Fornasiero, LLNL’s principal investigator of the project.

The new uniforms could be deployed in the field in less than 10 years.

“The goal of this science and technology program is to develop a focused, innovative technological solution for future chemical biological defense protective clothing,” said Tracee Whitfield, the DTRA [US Defense Threat Reduction Agency] science and technology manager for the Dynamic Multifunctional Material for a Second Skin Program. “Swatch-level 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 researchers have prepared a video describing their work,

Here’s a link to and a citation for the paper,

Ultrabreathable and Protective Membranes with Sub-5 nm Carbon Nanotube Pores by Ngoc Bui, Eric R. Meshot, Sangil Kim, José Peña, Phillip W. Gibson, Kuang Jen Wu, and Francesco Fornasiero. Advanced Materials Volume 28, Issue 28, pages 5871–5877, July 27, 2016 DOI: 10.1002/adma.201600740 Version of Record online: 9 MAY 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

Smart suits for US soldiers—an update of sorts from the Lawrence Livermore National Laboratory

The US military has funded a program named: ‘Dynamic Multifunctional Material for a Second Skin Program’ through its Defense Threat Reduction Agency’s (DTRA) Chemical and Biological Technologies Department and Sharon Gaudin’s Feb. 20,  2014 article for Computer World offers a bit of an update on this project,which was first reported in 2012,

A U.S. soldier is on patrol with his squad when he kneels to check something out, unknowingly putting his knee into a puddle of contaminants.

The soldier isn’t harmed, though, because he or she is wearing a smart suit that immediately senses the threat and transforms the material covering his knee into a protective state that repels the potential deadly bacteria.

Scientists at the Lawrence Livermore National Laboratory, a federal government research facility in Livermore, Calif., are using nanotechnology to create clothing designed to protect U.S. soldiers from chemical and biological attacks.

“The threat is nanoscale so we need to work in the nano realm, which helps to keep it light and breathable,” said Francesco Fornasiero, a staff scientist at the lab. “If you have a nano-size threat, you need a nano-sized defense.”

Fornasiero said the task is a difficult one, and the suits may not be ready for the field for another 10 to 20 years. [emphasis mine]

One option is to use carbon nanotubes in a layer of the suit’s fabric. Sweat and air would be able to easily move through the nanotubes. However, the diameter of the nanotubes is smaller than the diameter of bacteria and viruses. That means they would not be able to pass through the tubes and reach the person wearing the suit.

However, chemicals that might be used in a chemical attack are small enough to fit through the nanotubes. To block them, researchers are adding a layer of polymer threads that extend up from the top of the nanotubes, like stalks of grass coming up from the ground.

The threads are designed to recognize the presence of chemical agents. When that happens, they swell and collapse on top of the nanotubes, blocking anything from entering them.

A second option that the Lawrence Livermore scientists are working on involves similar carbon nanotubes but with catalytic components in a polymer mesh that sits on top of the nanotubes. The components would destroy any chemical agents they come in contact with. After the chemicals are destroyed, they are shed off, enabling the suit to handle multiple attacks.

An October 6, 2012 (NR-12-10-06) Lawrence Livermore National Laboratory (LLNL) news release details the -project and the proponents,

Lawrence Livermore National Laboratory scientists and collaborators are developing a new military uniform material that repels chemical and biological agents using a novel carbon nanotube fabric.

The material will be designed to undergo a rapid transition from a breathable state to a protective state. The highly breathable membranes would have pores made of a few-nanometer-wide vertically aligned carbon nanotubes that are surface modified with a chemical warfare agent-responsive functional layer. Response to the threat would be triggered by direct chemical warfare agent attack to the membrane surface, at which time the fabric would switch to a protective state by closing the CNT pore entrance or by shedding the contaminated surface layer.

High breathability is a critical requirement for protective clothing to prevent heat-stress and exhaustion when military personnel are engaged in missions in contaminated environments. Current protective military uniforms are based on heavyweight full-barrier protection or permeable adsorptive protective overgarments that cannot meet the critical demand of simultaneous high comfort and protection, and provide a passive rather than active response to an environmental threat.

To provide high breathability, the new composite material will take advantage of the unique transport properties of carbon nanotube pores, which have two orders of magnitude faster gas transport rates when compared with any other pore of similar size.

“We have demonstrated that our small-size prototype carbon nanotube membranes can provide outstanding breathability in spite of the very small pore sizes and porosity,” said Sangil Kim, another LLNL scientist in the Biosciences and Biotechnology Division. “With our collaborators, we will develop large area functionalized CNT membranes.”

Biological agents, such as bacteria or viruses, are close to 10 nanometers in size. Because the membrane pores on the uniform are only a few nanometers wide, these membranes will easily block biological agents.

However, chemical agents are much smaller in size and require the membrane pores to be able to react to block the threat. To create a multifunctional membrane, the team will surface modify the original prototype carbon nanotube membranes with chemical threat responsive functional groups. The functional groups on the membrane will sense and block the threat like gatekeepers on entrance. A second response scheme also will be developed: Similar to how a living skin peels off when challenged with dangerous external factors, the fabric will exfoliate upon reaction with the chemical agent. In this way, the fabric will be able to block chemical agents such as sulfur mustard (blister agent), GD and VX nerve agents, toxins such as staphylococcal enterotoxin and biological spores such as anthrax.

The project is funded for $13 million over five years with LLNL as the lead institution. The Livermore team is made up of Fornasiero [Francesco Fornasiero], Kim and Kuang Jen Wu. Other collaborators and institutions involved in the project include Timothy Swager at Massachusetts Institute of Technology, Jerry Shan at Rutgers University, Ken Carter, James Watkins, and Jeffrey Morse at the University of Massachusetts-Amherst, Heidi Schreuder-Gibson at Natick Soldier Research Development and Engineering Center, and Robert Praino at Chasm Technologies Inc.

“Development of chemical threat responsive carbon nanotube membranes is a great example of novel material’s potential to provide innovative solutions for the Department of Defense CB needs,” said Tracee Harris, the DTRA science and technology manager for the Dynamic Multifunctional Material for a Second Skin Program. “This futuristic uniform would allow our military forces to operate safely for extended time periods and successfully complete their missions in environments contaminated with chemical and biological warfare agents.”

The Laboratory has a history in developing carbon nanotubes for a wide range of applications including desalination. “We have an advanced carbon nanotube platform to build and expand to make advancements in the protective fabric material for this new project,” Wu said.

The new uniforms could be deployed in the field in less than 10 years. [emphasis mine]

Since Gaudin’s 2014 article quotes one of the LLNL’s scientists, Francesco Fornasiero, with an estimate for the suit’s deployment into the field as 10 – 20 years as opposed to the “less than 10 years” estimated in the news release, I’m guessing the problem has proved more complex than was first anticipated.

For anyone who’s interested in more details about  US soldiers and nanotechnology,

  • May 1, 2013 article by Max Cacas for Signal Online provides more details about the overall Smart Skin programme and its goals.
  • Nov. 15, 2013 article by Kris Walker for Azonano.com describes the Smart Skin project along with others including the intriguingly titled: ‘Warrior Web’.
  • website for MIT’s (Massachusetts Institute of Technology) Institute for Soldier Nanotechnologies Note: The MIT researcher mentioned in the LLNL news release is a faculty member of the Institute for Soldier Nanotechnologies.
  • website for the Defense Threat Reduction Agency