NANOTECH INNOVATIONS

Fashion designers and fiber scientists at Cornell have taken “functional clothing” to a whole new level. They have designed a garment that can prevent colds and flu and never needs washing, and another that destroys harmful gases and protects the wearer from smog and air pollution. The two-toned gold dress and metallic denim jacket, contain cotton fabrics coated with nanoparticles that give them functional qualities never before seen in the fashion world. Designed by Olivia Ong in the College of Human Ecology’s Department of Fiber Science and Apparel Design, the garments were infused with their unusual qualities by fiber science assistant professor Juan Hinestroza and his postdoctoral researcher Hong Dong. Apparel design assistant professor Van Dyke Lewis launched the collaboration by introducing Ong to Hinestroza several months ago.”We think this is one of the first times that nanotechnology has entered the fashion world,” Hinestroza said. He noted one drawback may be the garments’ price: one square yard of nano-treated cotton would cost about $10,000. Ong’s dress and jacket, part of her original fashion line called “Glitterati,” look innocently hip. But closer inspection — with a microscope, that is — shows an army of electrostatically charged nanoparticles creating a protective shield around the cotton fibers in the top part of the dress, and the sleeves, hood and pockets of the jacket.”It’s something really moving toward the future, and really advanced,” said Ong, who graduates in December and aspires to design school. “I thought this could potentially be what fashion is moving toward.”Dong explained that the fabrics were created by dipping them in solutions containing nanoparticles synthesized in Hinestroza’s lab. The resultant colors are not the product of dyes, but rather, reflections of manipulation of particle size or arrangement.The upper portion of the dress contains cotton coated with silver nanoparticles. Dong first created positively charged cotton fibers using ammonium- and epoxy-based reactions, inducing positive ionization. The silver particles, about 10-20 nanometers across (a nanometer is one-billionth of a meter) were synthesized in citric acid, which prevented nanoparticle agglomeration. Dipping the positively charged cotton into the negatively charged silver nanoparticle solution resulted in the particles clinging to the cotton fibers. Silver possesses natural antibacterial qualities that are strengthened at the nanoscale, thus giving Ong’s dress the ability to deactivate many harmful bacteria and viruses. The silver infusion also reduces the need to wash the garment, since it destroys bacteria, and the small size of the particles prevents soiling and stains.The denim jacket includes a hood, sleeves and pockets with soft, gray tweed cotton embedded with palladium nanoparticles, about 5-10 nanometers in length. To create the material, Dong placed negatively charged palladium crystals onto positively charged cotton fibers. Ong, though strictly a designer, was drawn especially to the science behind creating the anti-smog jacket.”I thought it would be cool if [wearers] could wipe their hands on their sleeves or pockets,” Ong said. Ong incorporated the resultant cotton fiber into a jacket with the ability to oxidize smog. Such properties would be useful for someone with allergies, or for protecting themselves from harmful gases in the contaminated air, such as in a crowded or polluted city.

Fabrics made from these smart yarns have potential application in professions that involve high risk. A police officer in danger, a firefighter who is hurt while at work, a wounded soldier at the warfront may not be in a position to send a message requesting for help. But the apparels infused with smart yarns would be able to do it. The clothes can be designed accordingly; to store energy, which will provide power to operate small electronic devices. A mobile phone or any other form of communication device attached with the clothing can transmit the information from the garment to a command post. It can also be used in garments and used for monitoring health. It also foresees lucrative applications as performance apparel.The concept of electrically sensitive clothing made from nanotube infused cotton yarn can be adapted in various fields based on their exposure to potential risks. The burgeoning interest in nano technology opens a floodgate of opportunities for developing new and innovative products in the textile sector.

Presently, smart fabrics are manufactured from metallic or optical fibres. They wear away quickly, and are brittle and uncomfortable. Laundry of such textiles also proves to be troublesome. Nano technology has come up with an innovative way of combining the two fibres; one natural and the other nano technology. Cotton yarn with a thickness of 1.5 millimeters is dipped a few times in a solution of a special sticky polymer in ethanol and dried. This enables the yarn to conduct power from a battery to illuminate light emitting diode device. The antibody anti-albumin is added to the carbon nanotube solution. Anti-albumin reacts with albumin, a protein that is found in blood. When the anti-albumin infused yarns were exposed to albumin, the conductivity is increased considerably. This method is more sensitive, simple and durable. By repeating the process a few times, normal cotton becomes a conductive material due to the carbon nano tubes which are conductive in nature. After the process is complete, the cotton yarn still retains its soft and supple features. This yarn is much better comparatively over the current designs available for electrically conducting fabrics. The only change in the yarn is that it turns into black color due to the presence of carbon.

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…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 fire-fighter, 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. 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.”

The scientists rendering of the complex nano_barcodes and the “sandwhiches” they’d look for to identify biological weapons. Credit: J. Tok. The scientists rendering of the complex nano_barcodes and the “sandwhiches” they’d look for to identify biological weapons. Credit: J. Tok. Microscopic metal wires marked with barcodes like so many boxes of grocery-store spaghetti maight someday help identify biological weapons much more quickly than today’s methods. The technology would allow soldiers to use the right kind of anti-pathogen protection at just the right time. At present, to identify biological weapons, whether a bacteria such as anthrax, a virus such as smallpox, or a toxin such as botulism, samples must be collected from the battlefield and cultured in controlled laboratories. The new system would be very small and work virtually instantaneous, said Jeffrey Tok, a researcher at Lawrence Livermore National Laboratory and team leader for a multi-institution group that is developing the system. How it’s made? The core of this portable, lickity-split bioweapon recognition system is an amalgamation of two parts. One is the tiny wires, which are about 250 nanometers around (about 300 times smaller than a human hair) and 6,000 nanometers long. The other is an assortment of antibodies, the proteins that the body produces to directly attack, or direct the immune system to attack, cells that viruses, bacteria, and other unpleasant intruders infect. Each type of pathogen calls for a unique antibody. The tiny wires—made by an independent company —are electrochemically formed and then layered with bands of silver, gold, and nickel to produce patterns that are similar to the ubiquitous barcodes found on products worldwide. Then antibodies are essentially glued to the miniscule wires. Just as a box of 9-inch nails gets one barcode and a box set of classic Nine Inch Nails CDs gets another, anthrax antibodies are attached to nanowires with one code and smallpox antibodies are attached to nanowires with another. “In the end you will have a pool of various striped nanowires each of which will have a unique antibody assigned to it, which is to detect for that particular pathogen,” Tok explained. How it works? To identify pathogens, millions of barcoded, antibody-carrying nanowires are floated in a neutral liquid called an assay buffer, into which samples of suspected pathogens are injected. If a pathogen (or a cell in the pathogen called an “antigen”) meets its corresponding antibodies, the two will join, creating a nanowwire, antibody, antigen sandwich that will fluoresce, or glow, under a special light. To ID the pathogens the system takes two digital mug shots in quick succession. In the first the special light is off, and the barcodes are visible. In the second the light is on and the pathogen-fingering nanowires are glowing. A computer then matches each glowing wire in photo two to its barcode in photo one. An important advantage of the system, Tok said, is that many kinds barcoded antibodies can be mixed together in the assay buffer liquid, which can be used over and over. For the test project four types of antibodies, and corresponding barcodes, were used. “In theory we could interrogate for as many as 100 different striped nanowires in one single snapshot,” he said “That makes the analysis very fast.”

Self-cleaning fabrics could revolutionize the sport apparel industry. The technology, created by scientists working for the U.S. Air Force, has already been used to create t-shirts and underwear that can be worn hygenically for weeks without washing. The new technology attaches nanoparticles to clothing fibers using microwaves. Then, chemicals that can repel water, oil and bacteria are directly bound to the nanoparticles. These two elements combine to create a protective coating on the fibers of the material. This coating both kills bacteria, and forces liquids to bead and run off. The U.S. military spent more than $20 million to develop the fabric, deriving from research originally intended to protect soldiers from biological weapons. Jeff Owens, one of the scientists who worked to develop the process, said, “During Desert Storm, most casualties were from bacterial infections—not accidents or friendly fire. We treated underwear for soldiers who tested them for several weeks and found they remained hygienic. They also helped clear up some skin complaints.” Science fiction writer Neal Stephenson wrote specifically about nanotech fabrics that stayed clean; he referred to “fabricules” in his 1995 novel The Diamond Age: …with a quick brush, John and Gwendolyn were able to transfer most of the dirt onto their white gloves. From there it went straight into the air. Most gentlemen’s and ladies’ gloves nowadays were constructed of infinitesimal fabricules that knew how to eject dirt…British news organizations pointed out that an earlier reference to the general idea of clothes that never got dirty can be found in the 1951 film “The Man in the White Suit.” Sci-fi fans can console themselves with the fact that the lead role was played by Alec Guiness, who of course played Obiwan Kenobi in the original Star Wars films.