Nanotechnology-based smart yarn for soldiers
Chinese and U.S. researchers have developed a carbon nanotube-coated smart yarn which can conduct electricity and be woven into textiles to detect blood or to monitor health. According to one of the lead researchers, today's smart textiles, which are made of metallic or optical fibers, are fragile and not comfortable. So the team combined two fibers, one natural and one created by nanotechnology, to build a new kind of smart textile. If a soldier wearing clothes made with this fabric was wounded, his mobile phone could alert a nearby patrol to save his life. But read more...
You can see above how this carbon-nanotube coated smart yarn can conduct enough electricity from a battery to power a light-emitting diode device. Researchers can use its conductivity to design garments that detect blood." (Credit: Nicholas Kotov lab, University of Michigan) You'll find a much larger version and another photo on this page.
This research project has been led at the University of Michigan by Nicholas Kotov, Professor of Chemical Engineering, and a member of his lab, PhD student Bongsup Shim. They've worked with Wei Chen, Chris Doty and Chuanlai Xu, researchers at Jiangnan University, Wuxi, Jiangsu Province, China.
So how did this team build these smart textiles? "To make these 'e-textiles,' the researchers dipped 1.5-millimeter thick cotton yarn into a solution of carbon nanotubes in water and then into a solution of a special sticky polymer in ethanol. After being dipped just a few times into both solutions and dried, the yarn was able to conduct enough power from a battery to illuminate a light-emitting diode device. 'This turns out to be very easy to do,' Kotov said. 'After just a few repetitions of the process, this normal cotton becomes a conductive material because carbon nanotubes are conductive.'"
What are the properties of these smart textiles? "The only perceptible change to the yarn is that it turned black, due to the carbon. It remained pliable and soft. In order to put this conductivity to use, the researchers added the antibody anti-albumin to the carbon nanotube solution. Anti-albumin reacts with albumin, a protein found in blood. When the researchers exposed their anti-albumin-infused smart yarn to albumin, they found that the conductivity significantly increased. Their new material is more sensitive and selective as well as more simple and durable than other electronic textiles, Kotov said."
And what could be the applications for such materials? "Clothing that can detect blood could be useful in high-risk professions, the researchers say. An unconscious firefighter, ambushed soldier, or police officer in an accident, for example, couldn't send a distress signal to a central command post. But the smart clothing would have this capability. Kotov says a communication device such as a mobile phone could conceivably transmit information from the clothing to a central command post."
In Carbon Nanotube Clothing Could Take Charge in an Emergency, Larry Greenemeier describes how these yarn could be used in a more expressive way. (Scientific American, December 12, 2008). " soldier is badly wounded on the battlefield in Afghanistan or Iraq by a roadside explosive. As he lies beside his vehicle, unable to reach his radio to contact his unit on his location and condition, blood from the wound seeps into his shirt. Luckily, its fibers are coated with cylindrical, nanosize carbon molecules that contain antibodies able to detect the presence of albumin, a protein common in blood. The shirt senses that its wearer is bleeding and sends a signal through the shirt's carbon nanotubes (1,000 times more conductive than copper) that activates an emergency radio-frequency beacon on the soldier's belt. This distress call is picked up by a nearby patrol that rushes to the aid of their wounded comrade. This may be the stuff of science fiction, but ongoing development of fabrics coated with carbon nanotubes and other nanoscale substances could someday make such smart clothing a reality, says Nicholas Kotov."
This research work has been published by Nano Letters, an American Chemical Society journal, under the title "Smart Electronic Yarns and Wearable Fabrics for Human Biomonitoring made by Carbon Nanotube Coating with Polyelectrolytes" (Volume 8, Issue 12, Pages 4151–4157, November 7, 2008). Here is a link to the abstract. "The idea of electronic yarns and textiles has appeared for quite some time, but their properties often do not meet practical expectations. In addition to chemical/mechanical durability and high electrical conductivity, important materials qualifications include weavablity, wearability, light weight, and 'smart' functionalities. Here we demonstrate a simple process of transforming general commodity cotton threads into intelligent e-textiles using a polyelectrolyte-based coating with carbon nanotubes (CNTs). [...] Along with integrated humidity sensing, we demonstrate that CNT-cotton threads can be used to detect albumin, the key protein of blood, with high sensitivity and selectivity. Notwithstanding future challenges, these proof-of-concept demonstrations provide a direct pathway for the application of these materials as wearable biomonitoring and telemedicine sensors, which are simple, sensitive, selective, and versatile."
For more information about this smart yarn, but written in plain English, you can read these other articles.
- Intelligent textiles for soldiers: An electric yarn (The Economist, December 10, 2008)
- Carbon-Nanotube Thread (Katherine Bourzac, Technology Review, November 19, 2008)
- And a previous post about Kotov's work, A plastic as solid as steel (Emerging Technology Trends blog, ZDNet, October 5, 2007)
Sources: University of Michigan, December 15, 2008; and various websites
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