When you think of futuristic clothing, you probably imagine lots of metallics, holographic accents, and textures. In fact, the sci-fi imagery that springs to mind is coming back into fashion, as evidenced by some recent runway trends (Below: Figure 1).
While we can’t say for certain what the fashion of the future will look like, many of us hope that clothing a few years from now will have some greatly enhanced function, making use of science to create cleaner, safer textiles. One way to achieve these goals is to use nanotechnology to do things like kill bacteria or remove dirt.
Nanotechnology in the clothing industry is not a new phenomenon. Beginning in the mid-2000s, many clothing companies started incorporating silver nanoparticles into their products. Silver nanoparticles are antimicrobial, which means they kill the bacteria that cause bad odors. By including these nanoparticles in fabric to prevent odor, the resulting clothes need to be washed less frequently. These nano-infused items range from socks to t-shirts and are still popular today.1 To learn more about the environmental implications of silver-nanoparticle impregnated fabric, visit our previous blog post here.
There is a lot more new technology beyond antimicrobial nanoparticles coming from the field of nano-fabrics. Other desirable clothing characteristics that could be achieved with nanotechnology include self-cleaning fabrics, water-repelling textiles, and clothing that can reduce odors by chemically changing the compounds that cause bad odor.2 These innovations would take advantage of nano- specific properties, particularly the high surface area per volume ratio of nano-sized materials that increase the exposure of active surfaces to the surrounding environment.
Some of these more futuristic-sounding features are already in development. Recently, fabrics coated with silver and copper nanomaterials were produced that can degrade organic matter, such as food and dirt, upon exposure to the sun. These nanomaterials absorb visible light, producing high energy “hot” electrons that can break down surrounding organic matter. The nano features are helpful because the increased surface area of silver or copper metal drastically increases surface-exposed sites that can form the “hot” electrons to help break down food and dirt.2,3 Incorporating these nanomaterials could thus help create clothes that clean themselves!
Nanotechnology can also be harnessed to produce water-repelling, or hydrophobic, materials. This application draws its inspiration from nature: many plants have foliage that is hydrophobic because of nano-scale structures on the leaves. You can observe water-repelling plant leaves on a dewy summer morning. Water droplets on a leaf tend to ball up into spheres instead of being absorbed into the surface (Figure 3). This phenomenon is called the “lotus effect” because it is especially potent for the leaves of the lotus plant.
The hydrophobicity of the lotus leaf also makes it self-cleaning; dirt that initially sticks to the leaf surface is often washed away by beads of water that roll off the plant due to its hydrophobicity (Figure 4).4 After studying the physical structure of lotus leaves, researchers understand that their superhydrophobic nature is partially due to the presence of nanostructures, which create a rough surface that repels water.4
Researchers are working to exploit the lotus effect to create artificial superhydrophobic fabrics. Imagine how convenient it would be if rain was completely repelled by your umbrella, to the point that you could wrap it up when you get inside- no having to shake it off or leave it open to dry! New nanofabrics can do just this because they contain patterned nano-silicone spikes. Silicone is naturally water resistant, and the use of nano-sized patterns makes the material even more hydrophobic. When a water droplet comes into contact with the surface of these materials, it balls up and slides off instead of being absorbed.5
Nanotechnology can also be used to chemically target and eliminate odor-causing molecules. Whereas the silver nanoparticles mentioned earlier prevent odor formation by killing bacteria, a second generation of odor-busting nanoparticles work by chemically targeting and modifying stinky compounds. Whereas things like fabric or room sprays merely mask odor, fabrics modified with these new nanomaterials could break down the source of the odor, making them better and more efficient at deodorizing. One group of researchers found that copper coated silica nanoparticles were effective at eliminating odor arising from ethyl mercaptan, which is a stinky chemical typically added to petroleum gas (which is odorless) to enable us to smell gas leaks. Interacting with the copper-silica nanoparticles modifies the ethyl mercaptan molecules and binds them to the surface of the particles, so there is less ethyl mercaptan left to smell bad.6 This second generation of odor-reducing nanoparticles may be more environmentally sound than antimicrobial silver, because the mechanism of odor elimination is targeted towards specific compounds as opposed to general bacterial toxicity.
So, will nano-fabrics be the future of clothing, enabling us to all have self-cleaning, water-resistant clothes that we only have to wash a few times a year? Only time will tell. The field of nano-fabrics is still very much in its infancy and it still faces some challenges. For example, washing clothes that contain antimicrobial silver releases nanoparticles into the waste water, giving them a limited effective lifetime as the nanomaterial washes out. Perhaps more important is the potential environmental risk of this nanoparticle release into the environment, which has incited continued debate and controversy, as metal nanoparticles can dissolve into toxic ions when exposed to environmental conditions.7,8 Newer nanofabric technologies may carry their own concerns, which have not yet been thoroughly studied. However, the potential benefits of nano-enhanced fabrics makes their use worth exploration. And with continued scientific advancement that will allow us to address environmental concerns, this sector of nanotechnology can only continue to grow.
- TryNano.org: Nano Waterproofing lesson plan (ages 8-18)
- NISEnet: Exploring Nanotechnology through Consumer Products lesson plan (ages 11+)
- Soutter, W. Nanotechnology in Clothing. AZO Nano, 2012. https://www.azonano.com/article.aspx?ArticleID=3129.
- Osborne, H. Self-cleaning clothes edge closer as scientists create textile cleansed of dirt by sunlight. International Business Times, 2016. https://www.ibtimes.co.uk/self-cleaning-clothes-edge-closer-scientists-create-textile-cleansed-dirt-by-sunlight-1551240.
- Anderson, S. R.; Mohammadtaheri, M.; Kumar, D.; O’Mullane, A. P.; Field, M. R.; Ramanathan, R.; Bansal, V. Adv. Mater. Interfaces 2016, 3(6), 1–8. DOI: 10.1002/admi.201500632.
- Nanowerk. Nanotechnology solutions for self-cleaning, dirt and water-repellent coatings. 2011. https://www.nanowerk.com/spotlight/spotid=19644.php.
- Evans, J. Nanotech clothing fabric ‘never gets wet.’ New Scientist, 2008. https://www.newscientist.com/article/dn16126-nanotech-clothing-fabric-never-gets-wet/.
- Singh, A.; Krishna, V.; Angerhofer, A.; Do, B.; MacDonald, G.; Moudgil, B. Langmuir 2010, 26(20), 15837–15844. doi: 10.1021/la100793u
- Mole, B. News Brief: Wash removes nano germ-killers https://www.sciencenewsforstudents.org/article/news-brief-wash-removes-nano-germ-killers.
- American Chemical Society. The impact of anti-odor clothing on the environment (press release) 2016. https://www.acs.org/content/acs/en/pressroom/presspacs/2016/acs-presspac-april-13-2016/the-impact-of-anti-odor-clothing-on-the-environment.html.
Thanks to the application of the wonder material graphene, the quest for producing durable, affordable, and mass-produced “smart textiles” has been given a new push.
Headed by Professor Monica Craciun from the University of Exeter Engineering department, an international group of researchers has developed a novel method for producing fully electronic fibers that can be integrated into the production of day-to-day clothing.
The development of the current generation of wearable electronics involves fixing devices to fabrics, which could make them extremely rigid and prone to malfunctioning. However, in the latest study, the electronic devices are embedded in the material’s fabric, and this is done by coating electronic fibers with durable and lightweight components that will enable showing images directly on the fabric.
According to the scientists, the discovery could transform the development of wearable electronic devices for applications in many different day-to-day applications, and also medical diagnostics and health monitoring, like blood pressure and heart rates.
The international collaborative study has been reported in the scientific journal Flexible Electronics. Experts from the Centre for Graphene Science at the University of Exeter, CenTexBel in Belgium, and the Universities of Aveiro and Lisbon in Portugal took part in the study.
For truly wearable electronic devices to be achieved, it is vital that the components are able to be incorporated within the material, and not simply added to it.
Monica Craciun, Professor and Study Co-Author, Engineering Department, University of Exeter.
Graphene is only one-atom thick, which makes it the thinnest substance with the ability to conduct electricity. It is also one of the strongest known materials and quite flexible. In recent years, the race has been on for engineers and scientists to adapt graphene for applications in wearable electronic devices.
The latest study applied existing polypropylene fibers—often employed in an array of commercial applications in the textile sector—to fix the novel, graphene-based electronic fibers to develop light-emitting and touch-sensor devices.
The innovative method means that the fabrics will be capable of integrating truly wearable displays but without the requirement for electrodes—wires of extra materials.
The incorporation of electronic devices on fabrics is something that scientists have tried to produce for a number of years, and is a truly game-changing advancement for modern technology.
Saverio Russo, Professor and Study Co-Author, Physics Department, University of Exeter.
The key to this new technique is that the textile fibres are flexible, comfortable and light, while being durable enough to cope with the demands of modern life.
Dr Ana Neves, Study Co-Author, Engineering Department, University of Exeter.
Earlier in 2015, an international group of researchers, including Dr Ana Neves, Professor Russo, and Professor Craciun from the University of Exeter, had developed a novel method to integrate flexible, transparent graphene electrodes into fibers often associated with the textile sector.
Prof. Dr. Andreas Greiner (left) and Prof. Dr. Seema Agarwal (right) with equipment for electrospinning at the University of Bayreuth. With backlighting, one can see the thin fibres from which nonwoven materials are formed.
Uncomfortable, rigid, with low air permeability: textile materials capable of conducting electricity can be awkward for day-to-day use. However, researchers at the University of Bayreuth, Donghua University in Shanghai, and Nanjing Forestry University have now developed new nonwoven materials that are electrically conductive as well as flexible and breathable. This paves the way for comfortable high-tech clothes which, for example, convert sunlight to warmth, supply wearable electronic devices with electricity, or contain sensors for fitness training.
|The scientists have published their findings in the journal npj Flexible Electronics (“Polymer nanofibre composite nonwovens with metal-like electrical conductivity”).|
|Prof. Dr. Andreas Greiner’s team of researchers at the University of Bayreuth and their Chinese partners have succeeded in producing electrically conductive nonwovens which have all the other characteristics you would expect from clothing that is suitable for daily use. The materials are flexible, and thus adapt to movements and changes in posture. In addition, they are air-permeable, meaning they do not interfere with the natural breathing of the skin.|
|The combination of these properties is based on a special production process. In contrast to common methods of production, metal wires were not inserted into finished textiles. Rather, the scientists modified classical electro-spinning, which has been used to produce nonwovens for many years: short electro-spun polymer fibres and small amounts of tiny silver wires with a diameter of only 80 nanometres are mixed in a liquid. Afterwards, they are filtered, dried, and briefly heated up. If the composition is right, the resulting nonwoven material exhibits a very high degree of electrical conductivity.|
|This opens up a whole range of possibilities for innovative applications, especially in the area of smart clothes (i.e. wearables). Everyday clothing, for example, can be equipped with solar cells such that the captured sunlight is converted to warmth, heating up the textiles themselves. Mobile phones, cameras, mini-computers, and other wearable electronic devices could be charged by plugging them into the textiles. Sensors installed in the clothes could provide athletes and trainers with important fitness and health data or could give family and friends information on its location.|
|“In addition to articles of clothing, similar functions could also just as easily be installed in textile materials for use in seats and instruments in cars or airplanes,” explained Prof. Dr. Andreas Greiner, Chair of Macromolecular Chemistry II at the University of Bayreuth.|
|“Our approach, which takes the production of conductive textiles as its basis, can in principle be applied to many different systems,” added Steffen Reich, doctoral researcher and lead author of the new study. As an example, he cites current Bayreuth research projects on microbial fuel cells, which could eventually be used as electrodes in such nonwoven materials.|
|The research findings that were published in npj Flexible Electronics resulted from close cooperation between the University of Bayreuth, Donghua University in Shanghai, and Nanjing Forestry University. It was only two years ago that the University of Bayreuth signed a cooperation agreement with Donghua University, which has had a research priority on the research and development of textiles since the establishment of the institution. The mutual exchange in research and teaching that was agreed on is now beginning to bear fruit.|
|Source: University of Bayreuth|
Credit: Jiesheng Ren
A new method for producing conductive cotton fabrics using graphene-based inks opens up new possibilities for flexible and wearable electronics, without the use of expensive and toxic processing steps.
Wearable, textiles-based electronics present new possibilities for flexible circuits, healthcare and environment monitoring, energy conversion, and many others. Now, researchers at the Cambridge Graphene Centre (CGC) at the University of Cambridge, working in collaboration with scientists at Jiangnan University, China, have devised a method for depositing graphene-based inks onto cotton to produce a conductive textile. The work, published in the journal Carbon, demonstrates a wearable motion sensor based on the conductive cotton.
Cotton fabric is among the most widespread for use in clothing and textiles, as it is breathable and comfortable to wear, as well as being durable to washing. These properties also make it an excellent choice for textile electronics. A new process, developed by Dr Felice Torrisi at the CGC, and his collaborators, is a low-cost, sustainable and environmentally-friendly method for making conductive cotton textiles by impregnating them with a graphene-based conductive ink.
Based on Dr Torrisi’s work on the formulation of printable graphene inks for flexible electronics, the team created inks of chemically modified graphene flakes that are more adhesive to cotton fibres than unmodified graphene. Heat treatment after depositing the ink on the fabric improves the conductivity of the modified graphene. The adhesion of the modified graphene to the cotton fibre is similar to the way cotton holds coloured dyes, and allows the fabric to remain conductive after several washes.
Although numerous researchers around the world have developed wearable sensors, most of the current wearable technologies rely on rigid electronic components mounted on flexible materials such as plastic films or textiles. These offer limited compatibility with the skin in many circumstances, are damaged when washed and are uncomfortable to wear because they are not breathable.
“Other conductive inks are made from precious metals such as silver, which makes them very expensive to produce and not sustainable, whereas graphene is both cheap, environmentally-friendly, and chemically compatible with cotton,” explains Dr Torrisi.
Co-author Professor Chaoxia Wang of Jiangnan University adds: “This method will allow us to put electronic systems directly into clothes. It’s an incredible enabling technology for smart textiles.”
“Turning cotton fibres into functional electronic components can open to an entirely new set of applications from healthcare and wellbeing to the Internet of Things,” says Dr Torrisi “Thanks to nanotechnology, in the future our clothes could incorporate these textile-based electronics and become interactive.”
Graphene is carbon in the form of single-atom-thick membranes, and is highly conductive. The group’s work is based on the dispersion of tiny graphene sheets, each less than one nanometre thick, in a water-based dispersion. The individual graphene sheets in suspension are chemically modified to adhere well to the cotton fibres during printing and deposition on the fabric, leading to a thin and uniform conducting network of many graphene sheets. This network of nanometre flakes is the secret to the high sensitivity to strain induced by motion. A simple graphene-coated smart cotton textile used as a wearable strain sensor has been shown to reliably detect up to 500 motion cycles, even after more than 10 washing cycles in normal washing machine.
The use of graphene and other related 2D materials (GRMs) inks to create electronic components and devices integrated into fabrics and innovative textiles is at the centre of new technical advances in the smart textiles industry. Dr Torrisi and colleagues at the CGC are also involved in the Graphene Flagship, an EC-funded, pan-European project dedicated to bringing graphene and GRM technologies to commercial applications.
Graphene and GRMs are changing the science and technology landscape with attractive physical properties for electronics, photonics, sensing, catalysis and energy storage. Graphene’s atomic thickness and excellent electrical and mechanical properties give excellent advantages, allowing deposition of extremely thin, flexible and conductive films on surfaces and – with this new method – also on textiles. This combined with the environmental compatibility of graphene and its strong adhesion to cotton make the graphene-cotton strain sensor ideal for wearable applications.
The research was supported by grants from the European Research Council’s Synergy Grant, the International Research Fellowship of the National Natural Science Foundation of China and the Ministry of Science and Technology of China. The technology is being commercialised by Cambridge Enterprise, the University’s commercialisation arm.
More information: Jiesheng Ren et al. Environmentally-friendly conductive cotton fabric as flexible strain sensor based on hot press reduced graphene oxide, Carbon (2017). DOI: 10.1016/j.carbon.2016.10.045
The number and variety of smart textiles and wearable electronic devices has increased significantly in the past few years, as they offer significant enhancements to human comfort, health and well-being.
Wearable low-power silicon electronics, light-emitting diodes (LEDs) fabricated on fabrics, textiles with integrated Lithium-ion batteries (LIB) and electronic devices such as smart glasses, watches and lenses have been widely investigated and commercialized (e.g. Google glass, Apple Watch).
There is increasing demand for wearable electronics from industries such as:
– Medical and healthcare monitoring and diagnostics.
– Sportswear and fitness monitoring (bands).
– Consumer electronics such as smart watches, smart glasses and headsets.
– Military GPS trackers, equipment (helmets) and wearable robots.
– Smart apparel and footwear in fashion and sport.
– Workplace safety and manufacturing.
However, improvements in sensors, flexible & printable electronics and energy devices are necessary for wider implementation and nanomaterials and/or their hybrids are enabling the next phase convergence of textiles, electronics and informatics.
They are opening the way for the integration of electronic components and sensors (e.g. heat and humidity) in high strength, flexible and electrically conductive textiles with energy storage and harvesting capabilities, biological functions, antimicrobial properties, and many other new functionalities.
The industry is now moving towards the development of electronic devices with flexible, thin, and large-area form factors.
Electronic devices that are fabricated on flexible substrates for application in flexible displays, electronic paper, smart packages, skin-like sensors, wearable electronics, implantable medical implements etc. is a fast growing market. Their future development depends greatly on the exploitation of advanced materials. (See Our YouTube Video – below)
Nanomaterials such as carbon nanotubes (CNT), silver nanowires graphene and other 2D materials are viewed as key materials for the future development of wearable electronics for implementation in healthcare and fitness monitoring, electronic devices incorporated into clothing and ‘smart skin’ applications (printed graphene-based sensors integrated with other 2D materials for physiological monitoring).
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Nanoengineered functional textiles are going to revolutionize the clothing that you’ll wear. The potential of nanotechnology in the development of new materials in the textile industry is considerable. On the one hand, existing functionality can be improved using nanotechnology and on the other, it could make possible the manufacture of textiles with entirely new properties or the combination of different functions in one textile material.
Applications of nanotechnology in textiles. (Reprinted with permission by American Chemical Society)
A first generation of nano-enhanced textiles benefitted from nano finishing: Coating the surface of textiles and clothing with nano particles is an approach to the production of highly active surfaces to have UV-blocking, antimicrobial, antistatic, flame retardant, water and oil repellent, wrinkle resistant, and self-cleaning properties.One stubborn hurdle that prevents nanomaterial-enhanced textiles from becoming more of a commercial reality is the insufficient durability of nanocoatings on textile fibers or the stability of various properties endowed by nanoparticles. Quite simply put, the ‘smart’ comes off during washing.While antimicrobial properties are exerted by nano-silver, UV blocking, self-cleaning and flame-retardant properties are imparted by nano-metal oxide coatings. Zinc oxide nanoparticles embedded in polymer matrices like soluble starch are a good example of functional nanostructures with potential for applications such as UV-protection ability in textiles and sunscreens, and antibacterial finishes in medical textiles and inner wears.
Read More About: Nanotechnology In Textiles from AZO Nano
Sandy Mattei models a design by Matilda Ceesay with a Permethrin-releasing textile net. (Image: Cornell University)
A just published review paper in the February 26, 2016 online edition of ACS Nano (“Nanotechnology in Textiles”) discusses electronic and photonic nanotechnologies that are integrated with textiles and shows their applications in displays, sensing, and drug release within the context of performance, durability, and connectivity.In these smart clothes the textile structures themselves perform electronic or electric functions. Ideally, the nanoelectronic components will be completely fused with the textile material, resulting in that textile and non-textile components cannot be differentiated and ‘foreign particles’ can no longer be seen or felt.
Read More: Electronics in textiles
- flex-form energy dense rapid charge/ recharge batteries & super capacitors for textiles
- energy-scavenging fabrics that lead to wearable ‘smart’ clothes that can power integrated electronics and sensors through ordinary body movements;
- Interwoven solar cells that turn T-shirts into power textiles
- graphene yarns that facilitate energy storage textiles
- graphene-coated ‘e-textile’ that detect noxious gases
In their review, the authors discuss the electrical conductivity of conducting polymers and graphene, both of which are attractive for creating textiles that enable the incorporation of sensors and actuators.Another section of the review is dedicated to power sources suitable for e-textiles. This covers lightweight fabric carbon nanotube supercapacitor electrodes; stretchable graphene and PPy-based supercapacitors; triboelectric nanogenerators; flexible fiber and stripe batteries; and stretchable PPy-based supercapacitors for energy transfer.
(a) Schematic illustration of a wearable triboelectric nanogenerator. (b) Fabrication process of the nanopatterned PDMS structure. (c) FE-SEM images of the bottom textile with nanopatterned PDMS. Inset is a high-resolution image clearly showing the ZnO NR-templated PDMS nanopatterns. (d) Photographic image of the flexible, foldable WTNG. (Reproduced with permission by American Chemical Society) (click on image to enlarge)
Adding digital components to these e-textiles would open up an entirely new area of functional clothing. OLEDs in fiber form could lead to revolutionary applications by integrating optical and optoelectronic devices into textile. Combined with nanoelectronic devices, we might one day see flexible optical sensors and display screens woven into shirts and other garments. You could literally wear your next-generation smart phone or iPad on your sleeves; including the solar panels to power them (read more: “Light-emitting nanofibers shine the way for optoelectronic textiles“).
Photonic technologies for textiles
Want your clothes to change color at the push of a button, in response to ambient heat or illumination, warning you about airborne pollutants or pollen, or glow in the dark? The integration of optical technologies into garments will make this possible.As the authors write, “photonic materials and devices including films, nanoadditives, or optical fibers have been adopted in the fabrication of textiles and garments to not only enhance the aesthetic performance but also endow the garments with additional functionalities. The most distinctive and basic application of optical technologies on fabrics or garments is perhaps tuning their appearance by controlling the intensity, color, and pattern of light.”For example, optical films made of periodical dielectric multilayers could be directly coated on fabrics, thus offering a highly reflective colorful appearance and enabling different color perceptions depending on the angle of observation. Holographic films may also achieve similar functions and even provide a more complex 3D visual effect.”
Sensing and drug release in textiles
Lab-on-fiber technology will allow the implementation of sophisticated, autonomous multifunction sensing and actuating systems – all integrated in individual optical fibers. Such multifunctional labs integrated into a single optical fiber, exchanging information and combining sensorial data, could provide effective auto-diagnostic features as well as new photonic and electro-optic functionalities.
The general sensing principle of a plasmonic fiber sensor is described in detail in the review paper: “In a plasmonic fiber sensor, a lossy surface plasmon mode propagating along a metal/dielectric interface can be excited at its resonance by an optical fiber core-guided mode via evanescent wave coupling when the phase-matching condition between the two modes is satisfied at a certain frequency. The presence of such a plasmonic mode manifests itself as a spectral dip in the fiber transmission spectrum, with its spectral location corresponding to the phase-matching frequency. Variations in the refractive index of an analyte adjacent to the metal layer could significantly modify the phase-matching condition, thus displacing the spectral dip in the optical fiber transmission spectrum.”Already, temperature, humidity, and pressure sensors have been incorporated in textiles.
In future, microfluidics can be incorporated in thread-based channels for application in point-of-care diagnostics. Combined with LEDs, these textiles can give visual sensing information. Combined with drug-loaded nanoparticles, textile fibers could provide programmable release of therapeutic drugs.For example, the designer Matilda Ceesay created a hooded body suit embedded at the molecular level with insecticides to ward off mosquitoes infected with malaria. The cotton mesh used for this anti-malaria garment was coated with a material where an insect repellent and fabric are bound at the nano level using metal organic framework molecules (MOFs).Concluding their review, after an extensive discussion of fabrication methods and functionalities, the authors also address the issues of toxicity of nanomaterials in textiles as well as commercial trends in the global nanotechnology-enhanced textile market.
Contributed By Michael Berger
Genesis Nanotechnology, Inc.
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The standard appearance of today’s electronic devices as solid, black objects could one day change completely as researchers make electronic components that are transparent and flexible. Working toward this goal, researchers in a new study have developed transparent, flexible supercapacitors made of carbon nanotube films. The high-performance devices could one day be used to store energy for everything from wearable electronics to photovoltaics.
The researchers, Kanninen et al., from institutions in Finland and Russia, have published a paper on the new supercapacitors in a recent issue of Nanotechnology.
In general, supercapacitors can store several times more charge in a given volume or mass than traditional capacitors, have faster charge and discharge rates, and are very stable. Over the past few years, researchers have begun working on making supercapacitors that are transparent and flexible due to their potential use in a wide variety of applications.
“Potential applications can be roughly divided into two categories: high-aesthetic-value products, such as activity bands and smart clothes, and inherently transparent end-uses, such as displays and windows,” coauthor Tanja Kallio, an associate professor at Aalto University who is currently a visiting professor at the Skolkovo Institute of Science and Technology, told Phys.org. “The latter include, for example, such future applications as smart windows for automobiles and aerospace vehicles, self-powered rolled-up displays, self-powered wearable optoelectronics, and electronic skin.”
The type of supercapacitor developed here, called an electrochemical double-layer capacitor, is based on high-surface-area carbon. One prime candidate for this material is single-walled carbon nanotubes due to their combination of many appealing properties, including a large surface area, high strength, high elasticity, and the ability to withstand extremely high currents, which is essential for fast charging and discharging.
The problem so far, however, has been that the carbon nanotubes must be prepared as thin films in order to be used as electrodes in supercapacitors. Current techniques for preparing single-walled carbon nanotube thin films have drawbacks, often resulting in defected nanotubes, limited conductivity, and other performance limitations.
In the new study, the researchers demonstrated a new method to fabricate thin films made of single-walled carbon nanotubes using a one-step aerosol synthesis method. When incorporated into a supercapacitor, the thin films exhibit the highest transparency to date (92%), the highest mass specific capacitance (178 F/g), and one of the highest area specific capacitances (552 µF/cm2) compared to other carbon-based, flexible, transparent supercapacitors. The films also have a high stability, as demonstrated by the fact that their capacitance does not degrade after 10,000 charging cycles.
With these advantages, the new device illustrates the continued improvement in the development of transparent, flexible supercapacitors. In the future, the researchers plan to further improve the energy density, flexibility, and durability, and also make the supercapacitors stretchable.
“One more important characteristic to be realized and urgently expected in future electronics is the stretchability of the conductive materials and assembled electronic components,” said coauthor Albert Nasibulin, a professor at the Skolkovo Institute of Science and Technology and an adjunct professor at Aalto University. “Together with Tanja, we are currently working on a new type of stretchable and transparent single-walled carbon nanotube supercapacitor. We are confident that one can create prototypes based on carbon nanotubes that might withstand 100% elongation with no performance degradation.”
Explore further: Researchers develop stretchable wire-shaped supercapacitor
More information: Kanninen et al. “Transparent and flexible high-performance supercapacitors based on single-walled carbon nanotube films.” Nanotechnology. DOI: 10.1088/0957-4484/27/23/235403
Genesis Nanotechnology, Inc. ~ “Great Things from Small Things”
Photo: M. Scott Brauer
National public-private consortium led by MIT will involve manufacturers, universities, agencies, companies.
A wide range of industries are expected to benefit from these revolutionary fibers and textiles, including apparel, consumer products, automotive, medical devices, and consumer electronics. “Fibers and fabrics are ubiquitous,” Fink says. “Our institute will go everywhere a fiber and fabric goes.”
An independent nonprofit founded by MIT has been selected to run a new, $317 million public-private partnership announced today by Secretary of Defense Ashton Carter.
The partnership, named the Advanced Functional Fibers of America (AFFOA) Institute, has won a national competition for federal funding to create the latest Manufacturing Innovation Institute. It is designed to accelerate innovation in high-tech, U.S.-based manufacturing involving fibers and textiles.
The proposal for the institute was led by Professor Yoel Fink, director of MIT’s Research Laboratory of Electronics (RLE). The partnership includes 32 universities, 16 industry members, 72 manufacturing entities, and 26 startup incubators, spread across 27 states and Puerto Rico.
This is the eighth Manufacturing Innovation Institute established to date, and the first to be headquartered in New England. The headquarters will be established in Cambridge, Massachusetts, in proximity to the MIT campus and its U.S. Army-funded Institute for Soldier Nanotechnology, as well as the Natick Soldier Research Development and Engineering Center.
This unique partnership, Fink says, has the potential to create a whole new industry, based on breakthroughs in fiber materials and manufacturing. These new fibers and the fabrics made from them will have the ability to see, hear, and sense their surroundings; communicate; store and convert energy; monitor health; control temperature; and change their color.
The new initiative will receive $75 million in federal funding out of a total of $317 million through cost sharing among the Department of Defense, industrial partners, venture capitalists, universities, nonprofits, and states including the Commonwealth of Massachusetts. The initial funding will cover a five-year period and will be administered through the new, independent, nonprofit organization set up for the purpose. The partnership, which will focus on both developing new technologies and training the workforce needed to operate and maintain these production systems, also includes a network of community colleges and experts in career and technical education for manufacturing.
“Massachusetts’s innovation ecosystem is reshaping the way that people interact with the world around them,” says Massachusetts Gov. Charlie Baker. “This manufacturing innovation institute will be the national leader in developing and commercializing textiles with extraordinary properties. It will extend to an exciting new field our ongoing efforts to nurture emerging industries, and grow them to scale in Massachusetts. And it will serve as a vital piece of innovation infrastructure, to support the development of the next generation of manufacturing technology, and the development of a highly skilled workforce.”
“Through this manufacturing innovation institute, Massachusetts researchers and Massachusetts employers will collaborate to unlock new advances in military technology, medical care, wearable technology, and fashion,” adds Massachusetts Lt. Gov. Karyn Polito. “This, in turn, will help drive business expansion, support the competitiveness of local manufacturers, and create new employment opportunities for residents across the Commonwealth.”
Announcing the new institute at an event at MIT, Carter stressed the importance of technology and innovation to the mission of the Department of Defense and to national security broadly: “The intersection of the two is truly an opportunity-rich environment. These issues matter. They have to do with our protection and our security, and creating a world where our fellow citizens can go to school and live their lives, and dream their dreams, and one day give their children a better future. Helping defend your country and making a better world is one of the noblest things that a business leader, a technologist, an entrepreneur, or a young person can do, and we’re all grateful to all of you for doing that with us.”
A new age of fabrics
For thousands of years, humans have used fabrics in much the same way, to provide basic warmth and aesthetics. Clothing represents “one of the most ancient forms of human expression,” Fink says, but one that is now, for the first time, poised to undergo a profound transformation — the dawn of a “fabric revolution.”
“What makes this point in time different? The answer is research,” Fink says: Objects that serve many complex functions are always made of multiple materials, whereas single-material objects, such as a drinking glass, usually have just a single, simple function. But now, new technology — some of it developed in Fink’s own laboratory — is changing all that, making it possible to integrate many materials and complex functional structures into a fabric’s very fibers, and to create fiber-based devices and functional fabric systems.
The semiconductor industry has shown how to combine millions of transistors into an integrated circuit that functions as a system; as described by “Moore’s law,” the number of devices and functions has doubled in computer chips every couple of years. Fink says the team envisions that the number of functions in a fiber will grow with similar speed, paving the way for highly functional fabrics.
The challenge now is to execute this vision, Fink says. While many textile and apparel companies and universities have figured out pieces of this puzzle, no single one has figured it all out.
“It turns out there is no company or university in the world that knows how to do all of this,” Fink says. “Instead of creating a single brick-and-mortar center, we set out to assemble and organize companies and universities that have manufacturing and ‘making’ capabilities into a network — a ‘distributed foundry’ capable of addressing the manufacturing challenges. To date, 72 manufacturing entities have signed up to be part of our network.”
“With a capable manufacturing network in place,” Fink adds, “the question becomes: How do we encourage and foster product innovation in this new area?” The answer, he says, lies at the core of AFFOA’s activities: Innovators across the country will be invited to execute “advanced fabric” products on prototyping and pilot scales. Moreover, the center will link these innovators with funding from large companies and venture capital investors, to execute their ideas through the manufacturing stage. The center will thus lower the barrier to innovation and unleash product creativity in this new domain, he says.
Promoting leadership in manufacturing
The federal selection process for the new institute was administered by the U.S. Department of Defense’s Manufacturing Technology Program and the U.S. Army’s Natick Soldier Research, Development and Engineering Center and Contracting Command in New Jersey. Retired Gen. Paul J. Kern will serve as chairman of the AFFOA Institute.
As explained in the original call for proposals to create this institute, the aim is to ensure “that America leads in the manufacturing of new products from leading edge innovations in fiber science, commercializing fibers and textiles with extraordinary properties. Known as technical textiles, these modern day fabrics and fibers boast novel properties ranging from being incredibly lightweight and flame resistant, to having exceptional strength. Technical textiles have wide-ranging applications, from advancing capabilities of protective gear allowing fire fighters to battle the hottest flames, to ensuring that a wounded soldier is effectively treated with an antimicrobial compression bandage and returned safely.”
In addition to Fink, the new partnership will include Tom Kochan, the George Maverick Bunker Professor of Management at MIT’s Sloan School of Management, who will serve as chief workforce officer coordinating the nationwide education and workforce development (EWD) plan. Pappalardo Professor of Mechanical Engineering Alexander Slocum will be the EWD deputy for education innovation. Other key MIT participants will include professors Krystyn Van Vliet from the Materials Science and Engineering and Biological Engineering departments; Peko Hosoi and Kripa Varanasi from the Department of Mechanical Engineering; and Gregory Rutledge from the Department of Chemical Engineering.
Among the industry partners who will be members of the partnership are companies such as Warwick Mills, DuPont, Steelcase, Nike, and Corning. Among the academic partners are Drexel University, the University of Massachusetts at Amherst, the University of Georgia, the University of Tennessee, and the University of Texas at Austin.
In a presentation last fall about the proposed partnership, MIT President L. Rafael Reif said, “We believe that partnerships — with industry and government and across academia — are critical to our capacity to create positive change.” He added, “Our nation has no shortage of smart, ambitious people with brilliant new ideas. But if we want a thriving economy, producing more and better jobs, we need more of those ideas to get to market faster.” Accelerating such implementation is at the heart of the new partnership’s goals.
Connecting skills, workers, and jobs
This partnership, Reif said, will be “a system that connects universities and colleges with motivated companies and with far-sighted government agencies, so we can learn from each other and work with each other. A system that connects workers with skills, and skilled workers with jobs. And a system that connects advanced technology ideas to the marketplace or to those who can get them to market.”
Part of the power of this new collaboration, Fink says, is combining the particular skills and resources of the different partners so that they “add up to something that’s more than the sum of the parts.” Existing large companies can contribute both funding and expertise, smaller startup companies can provide their creative new ideas, and the academic institutions can push the research boundaries to open up new technological possibilities.
“MIT recognizes that advancing manufacturing is vital to our innovation process, as we explored in our Production in the Innovation Economy (PIE) study,” says MIT Provost Martin Schmidt. “AFFOA will connect our campus even more closely with industries (large and small), with educational organizations that will develop the skilled workers, and with government at the state and federal level — all of whom are necessary to advance this new technology. AFFOA is an exciting example of the public-private partnerships that were envisioned in the recommendation of the Advanced Manufacturing Partnership.”
“Since MIT’s start, there has always been an emphasis on ‘mens et manus,’ using our minds and hands to make inventions useful at scales that impact the nation and the world,” adds Van Vliet, the director of manufacturing innovation for MIT’s Innovation Initiative, who has served as the faculty lead in coordinating MIT’s response to manufacturing initiatives that result from the Advanced Manufacturing Partnership. “What makes this new partnership very exciting is, this is for the first time a manufacturing institute headquartered in our region that connects our students and our faculty with local and national industrial partners, to really scale up production of many new fiber and textile technologies.”
“Participating in this group of visionaries from government, academia, and industry — who are all motivated by the goal of advancing a new model of American textile manufacturing and helping to develop new products for the public and defense sectors — has been an exciting process,” says Aleister Saunders, Drexel University’s senior vice provost for research and a leader of its functional fabrics center. “Seeing the success we’ve already had in recruiting partners at the local level leads me to believe that on a national level, these centers of innovation will be able to leverage intellectual capital and regional manufacturing expertise to drive forward new ideas and new applications that will revolutionize textile manufacturing across the nation.”
“Revolutionary fabrics and fibers are modernizing everything from battlefield communication to medical care,” says U.S. Congressmen Joe Kennedy III (D-Mass.). “That the Commonwealth would be chosen to lead the way is no surprise. From Lowell to Fall River, our ability to merge cutting-edge technology with age-old ingenuity has sparked a new day for the textile industry. With its unparalleled commitment to innovation, MIT is the perfect epicenter for scaling these efforts. I applaud President Reif, Professor Fink, and all of the partners involved for this tremendous success.”
The innovations that led to the “internet of things” and the widespread incorporation of digital technology into manufacturing have brought about a revolution whose potential is unlimited and will generate “brilliant ideas that people will be able to bring to this task of making sure that America stays number one in each and every one of these fields,” said Senator Ed Markey (D-Mass.) at the MIT event. “The new institute we are announcing today will help ensure that both Massachusetts and the United States can expand our technological edge in a new generation of fiber science.”
A wide range of industries are expected to benefit from these revolutionary fibers and textiles, including apparel, consumer products, automotive, medical devices, and consumer electronics. “Fibers and fabrics are ubiquitous,” Fink says. “Our institute will go everywhere a fiber and fabric goes.”
Genesis Nanotechnology, Inc. ~ “Great Things from Small Things”
The transistor is the most fundamental building block of electronics, used to build circuits capable of amplifying electrical signals or switching them between the 0s and 1s at the heart of digital computation. Transistor fabrication is a highly complex process, however, requiring high-temperature, high-vacuum equipment.
Now, University of Pennsylvania engineers have shown a new approach for making these devices: sequentially depositing their components in the form of liquid nanocrystal “inks.”
Their new study, published in Science, opens the door for electrical components to be built into flexible or wearable applications, as the lower-temperature process is compatible with a wide array of materials and can be applied to larger areas.
The researchers’ nanocrystal-based field effect transistors were patterned onto flexible plastic backings using spin coating but could eventually be constructed by additive manufacturing systems, like 3-D printers.
The study was lead by Cherie Kagan, the Stephen J. Angello Professor in the School of Engineering and Applied Science, and Ji-Hyuk Choi, then a member of her lab, now a senior researcher at the Korea Institute of Geoscience and Mineral Resources. Han Wang, Soong Ju Oh, Taejong Paik and Pil Sung Jo of the Kagan lab contributed to the work. They collaborated with Christopher Murray, a Penn Integrates Knowledge Professor with appointments in the School of Arts & Sciences and Penn Engineering; Murray lab members Xingchen Ye and Benjamin Diroll; and Jinwoo Sung of Korea’s Yonsei University.
The researchers began by taking nanocrystals, or roughly spherical nanoscale particles, with the electrical qualities necessary for a transistor and dispersing these particles in a liquid, making nanocrystal inks.
Kagan’s group developed a library of four of these inks: a conductor (silver), an insulator (aluminum oxide), a semiconductor (cadmium selenide) and a conductor combined with a dopant (a mixture of silver and indium). “Doping” the semiconductor layer of the transistor with impurities controls whether the device transmits a positive or negative charge.
“These materials are colloids just like the ink in your inkjet printer,” Kagan said, “but you can get all the characteristics that you want and expect from the analogous bulk materials, such as whether they’re conductors, semiconductors or insulators.
“Our question was whether you could lay them down on a surface in such a way that they work together to form functional transistors.”
The electrical properties of several of these nanocrystal inks had been independently verified, but they had never been combined into full devices.
“This is the first work,” Choi said, “showing that all the components, the metallic, insulating, and semiconducting layers of the transistors, and even the doping of the semiconductor could be made from nanocrystals.”
Such a process entails layering or mixing them in precise patterns.
First, the conductive silver nanocrystal ink was deposited from liquid on a flexible plastic surface that was treated with a photolithographic mask, then rapidly spun to draw it out in an even layer. The mask was then removed to leave the silver ink in the shape of the transistor’s gate electrode. The researchers followed that layer by spin-coating a layer of the aluminum oxide nanocrystal-based insulator, then a layer of the cadmium selenide nanocrystal-based semiconductor and finally another masked layer for the indium/silver mixture, which forms the transistor’s source and drain electrodes. Upon heating at relatively low temperatures, the indium dopant diffused from those electrodes into the semiconductor component.
“The trick with working with solution-based materials is making sure that, when you add the second layer, it doesn’t wash off the first, and so on,” Kagan said. “We had to treat the surfaces of the nanocrystals, both when they’re first in solution and after they’re deposited, to make sure they have the right electrical properties and that they stick together in the configuration we want.”
Because this entirely ink-based fabrication process works at lower temperatures than existing vacuum-based methods, the researchers were able to make several transistors on the same flexible plastic backing at the same time.
“Making transistors over larger areas and at lower temperatures have been goals for an emerging class of technologies, when people think of the Internet of things, large area flexible electronics and wearable devices,” Kagan said. “We haven’t developed all of the necessary aspects so they could be printed yet, but because these materials are all solution-based, it demonstrates the promise of this materials class and sets the stage for additive manufacturing.”
Explore further: Particle-free silver ink prints small, high-performance electronics
More information: “Exploiting the colloidal nanocrystal library to construct electronic devices” DOI: 10.1126/science.aad0371