Graphene Could Revolutionize the Development of Wearable Electronic Devices


 

graphenehydr

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.

graphene-supercapacitor

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Transparent loudspeakers and MICs that let your skin play music – Ultra-Thin Nanomembranes may help the Hearing and Speech Impaired


Skin Play Music 180918110939_1_540x360
Their ultrathin, conductive, and transparent hybrid NMs can be applied to the fabrication of skin-attachable NM loudspeakers and voice-recognition microphones, which would be unobtrusive in appearance due to their excellent transparency and conformal contact capability.Credit: UNIST

An international team of researchers, affiliated with UNIST has presented an innovative wearable technology that will turn your skin into a loudspeaker.

This breakthrough has been led by Professor Hyunhyub Ko in the School of Energy and Chemical Engineering at UNIST. Created in part to help the hearing and speech impaired, the new technology can be further explored for various potential applications, such as wearable IoT sensors and conformal health care devices.

In the study, the research team has developed ultrathin, transparent, and conductive hybrid nanomembranes with nanoscale thickness, consisting of an orthogonal silver nanowire array embedded in a polymer matrix. They, then, demonstrated their nanomembrane by making it into a loudspeaker that can be attached to almost anything to produce sounds. The researchers also introduced a similar device, acting as a microphone, which can be connected to smartphones and computers to unlock voice-activated security systems.

Nanomembranes (NMs) are molcularly thin seperation layers with nanoscale thickness. Polymer NMs have attracted considerable attention owing to their outstanding advantages, such as extreme flexibility, ultralight weight, and excellent adhesibility in that they can be attached directly to almost any surface. However, they tear easily and exhibit no electrical conductivity.

The research team has solved such issues by embedding a silver nanowire network within a polymer-based nanomembrane. This has enabled the demonstration of skin-attachable and imperceptible loudspeaker and microphone.

“Our ultrathin, transparent, and conductive hybrid NMs facilitate conformal contact with curvilinear and dynamic surfaces without any cracking or rupture,” says Saewon Kang in the doctroral program of Energy and Chemical Engineering at UNIST, the first author of the study.

He adds, “These layers are capable of detecting sounds and vocal vibrations produced by the triboelectric voltage signals corresponding to sounds, which could be further explored for various potential applications, such as sound input/output devices.”

Using the hybrid NMs, the research team fabricated skin-attachable NM loudspeakers and microphones, which would be unobtrusive in appearance because of their excellent transparency and conformal contact capability. These wearable speakers and microphones are paper-thin, yet still capable of conducting sound signals.

“The biggest breakthrough of our research is the development of ultrathin, transparent, and conductive hybrid nanomembranes with nanoscale thickness, less than 100 nanometers,” says Professor Ko. “These outstanding optical, electrical, and mechanical properties of nanomembranes enable the demonstration of skin-attachable and imperceptible loudspeaker and microphone.”

The skin-attachable NM loudspeakers work by emitting thermoacoustic sound by the temperature-induced oscillation of the surrounding air. The periodic Joule heating that occurs when an electric current passes through a conductor and produces heat leads to these temperature oscillations. It has attracted considerable attention for being a stretchable, transparent, and skin-attachable loudspeaker.

Wearable microphones are sensors, attached to a speaker’s neck to even sense the vibration of the vocal folds. This sensor operates by converting the frictional force generated by the oscillation of the transparent conductive nanofiber into electric energy. For the operation of the microphone, the hybrid nanomembrane is inserted between elastic films with tiny patterns to precisely detect the sound and the vibration of the vocal cords based on a triboelectric voltage that results from the contact with the elastic films.

“For the commercial applications, the mechanical durability of nanomebranes and the performance of loudspeaker and microphone should be improved further,” says Professor Ko.

Story Source:

Materials provided by Ulsan National Institute of Science and Technology(UNIST)Note: Content may be edited for style and length.


Journal Reference:

  1. Saewon Kang, Seungse Cho, Ravi Shanker, Hochan Lee, Jonghwa Park, Doo-Seung Um, Youngoh Lee, Hyunhyub Ko. Transparent and conductive nanomembranes with orthogonal silver nanowire arrays for skin-attachable loudspeakers and microphonesScience Advances, 2018; 4 (8): eaas8772 DOI: 10.1126/sciadv.aas8772

MIT: Introducing the latest in textiles: Soft hardware


MIT-Fiber-Diodes-01_0For the first time, the researchers from MIT and AFFOA have produced fibers with embedded electronics that are so flexible they can be woven into soft fabrics and made into wearable clothing.: Courtesy of the researchers

Researchers incorporate optoelectronic diodes into fibers and weave them into washable fabrics.

The latest development in textiles and fibers is a kind of soft hardware that you can wear: cloth that has electronic devices built right into it.

Researchers at MIT have now embedded high speed optoelectronic semiconductor devices, including light-emitting diodes (LEDs) and diode photodetectors, within fibers that were then woven at Inman Mills, in South Carolina, into soft, washable fabrics and made into communication systems. This marks the achievement of a long-sought goal of creating “smart” fabrics by incorporating semiconductor devices — the key ingredient of modern electronics — which until now was the missing piece for making fabrics with sophisticated functionality.

This discovery, the researchers  say, could unleash a new “Moore’s Law” for fibers — in other words, a rapid progression in which the capabilities of fibers would grow rapidly and exponentially over time, just as the capabilities of microchips have grown over decades.

The findings are described this week in the journal Nature in a paper by former MIT graduate student Michael Rein; his research advisor Yoel Fink, MIT professor of materials science and electrical engineering and CEO of AFFOA (Advanced Functional Fabrics of America); along with a team from MIT, AFFOA, Inman Mills, EPFL in Lausanne, Switzerland, and Lincoln Laboratory.

A spool of fine, soft fiber made using the new process shows the embedded LEDs turning on and off to demonstrate their functionality. The team has used similar fibers to transmit music to detector fibers, which work even when underwater. (Courtesy of the researchers)

Optical fibers have been traditionally produced by making a cylindrical object called a “preform,” which is essentially a scaled-up model of the fiber, then heating it. Softened material is then drawn or pulled downward under tension and the resulting fiber is collected on a spool.

The key breakthrough for producing  these new fibers was to add to the preform light-emitting semiconductor diodes the size of a grain of sand, and a pair of copper wires a fraction of a hair’s width. When heated in a furnace during the fiber-drawing process, the polymer preform partially liquified, forming a long fiber with the diodes lined up along its center and connected by the copper wires.

In this case, the solid components were two types of electrical diodes made using standard microchip technology: light-emitting diodes (LEDs) and photosensing diodes. “Both the devices and the wires maintain their dimensions while everything shrinks around them” in the drawing process, Rein says. The resulting fibers were then woven into fabrics, which were laundered 10 times to demonstrate their practicality as possible material for clothing.

“This approach adds a new insight into the process of making fibers,” says Rein, who was the paper’s lead author and developed the concept that led to the new process. “Instead of drawing the material all together in a liquid state, we mixed in devices in particulate form, together with thin metal wires.”

One of the advantages of incorporating function into the fiber material itself is that the resulting  fiber is inherently waterproof. To demonstrate this, the team placed some of the photodetecting fibers inside a fish tank. A lamp outside the aquarium transmitted music (appropriately, Handel’s “Water Music”) through the water to the fibers in the form of rapid optical signals. The fibers in the tank converted the light pulses — so rapid that the light appears steady to the naked eye — to electrical signals, which were then converted into music. The fibers survived in the water for weeks.

Though the principle sounds simple, making it work consistently, and making sure that the fibers could be manufactured reliably and in quantity, has been a long and difficult process. Staff at the Advanced Functional Fabric of America Institute, led by Jason Cox and Chia-Chun Chung, developed the pathways to increasing yield, throughput, and overall reliability, making these fibers ready for transitioning to industry. At the same time, Marty Ellis from Inman Mills developed techniques for weaving these fibers into fabrics using a conventional industrial manufacturing-scale loom.

“This paper describes a scalable path for incorporating semiconductor devices into fibers. We are anticipating the emergence of a ‘Moore’s law’ analog in fibers in the years ahead,” Fink says. “It is already allowing us to expand the fundamental capabilities of fabrics to encompass communications, lighting, physiological monitoring, and more. In the years ahead fabrics will deliver value-added services and will no longer just be selected for aesthetics and comfort.”

He says that the first commercial products incorporating this technology will be reaching the marketplace as early as next year — an extraordinarily short progression from laboratory research to commercialization. Such rapid lab-to-market development was a key part of the reason for creating an academic-industry-government collaborative such as AFFOA in the first place, he says. These initial applications will be specialized products involving communications and safety. “It’s going to be the first fabric communication system. We are right now in the process of transitioning the technology to domestic manufacturers and industry at an unprecendented speed and scale,” he says.

In addition to commercial applications, Fink says the U.S. Department of Defense — one of AFFOA’s major supporters — “is exploring applications of these ideas to our women and men in uniform.”

Beyond communications, the fibers could potentially have significant applications in the biomedical field, the researchers say. For example, devices using such fibers might be used to make a wristband that could measure pulse or blood oxygen levels, or be woven into a bandage to continuously monitor the healing  process.

The research was supported in part by the MIT Materials Research Science and Engineering Center (MRSEC) through the MRSEC Program of the National Science Foundation, by the U.S. Army Research Laboratory and the U.S. Army Research Office through the Institute for Soldier Nanotechnologies. This work was also supported by the Assistant Secretary of Defense for Research and Engineering.

An Ultra-Thin – Wearable Health Monitor made possible by a ‘Graphene Ink Tattoo’ designed and developed at the University of Texas at Austin


University of Texas at Austin. This is the world’s thinnest wearable Health Monitor, designed and developed by the researchers at the University of Texas at Austin, in the form of a “Graphene-Ink Tattoo”.

Most health monitors in use today are bulky and tend to restrict patients movements. This graphene tattoo will eliminate these restrictions. It picks up electric signal given off by the body and transmits it to a smartphone app.

Watch the Video:

Abstract: Tattoo-like epidermal sensors are an emerging class of truly wearable electronics, owing to their thinness and softness. While most of them are based on thin metal films, a silicon membrane, or nanoparticle-based printable inks, we report sub-micrometer thick, multimodal electronic tattoo sensors that are made of graphene.UT Autin Graphene Ink Tattoo maxresdefault (2)

The graphene electronic tattoo (GET) is designed as filamentary serpentines and fabricated by a cost- and time-effective “wet transfer, dry patterning” method. It has a total thickness of 463 ± 30 nm, an optical transparency of ∼85%, and a stretchability of more than 40%.

The GET can be directly laminated on human skin just like a temporary tattoo and can fully conform to the microscopic morphology of the surface of skin viajust van der Waals forces. The open-mesh structure of the GET makes it breathable and its stiffness negligible. A bare GET is able to stay attached to skin for several hours without fracture or delamination.

Wearable Health Patches 150929112030_1_540x360With liquid bandage coverage, a GET may stay functional on the skin for up to several days. As a dry electrode, GET–skin interface impedance is on par with medically used silver/silver-chloride (Ag/AgCl) gel electrodes, while offering superior comfort, mobility, and reliability. GET has been successfully applied to measure electrocardiogram (ECG), electromyogram (EMG), electroencephalogram (EEG), skin temperature, and skin hydration.

Read More Here

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Scientists Create Customizable, Fabric-Like Power Source for Wearable Electronics


supercap for wearables

Scientists at Nanyang Technological University, Singapore (NTU Singapore) have created a customizable, fabric-like power source that can be cut, folded or stretched without losing its function.

Led by Professor Chen Xiaodong, Associate Chair (Faculty) at the School of Materials Science & Engineering, the team reported in the journal Advanced Materials (print edition 8 January) how they have created the wearable power source, a supercapacitor, which works like a fast-charging battery and can be recharged many times.

Crucially, they have made their supercapacitor customizable or “editable”, meaning its structure and shape can be changed after it is manufactured, while retaining its function as a power source. Existing stretchable supercapacitors are made into predetermined designs and structures, but the new invention can be stretched multi-directionally, and is less likely to be mismatched when it is joined up to other electrical components.wearable-textiles-100616-0414_powdes_ti_f1

The new supercapacitor, when edited into a honeycomb-like structure, has the ability to store an electrical charge four times higher than most existing stretchable supercapacitors. In addition, when stretched to four times its original length, it maintains nearly 98 per cent of the initial ability to store electrical energy, even after 10,000 stretch-and-release cycles.

Experiments done by Prof Chen and his team also showed that when the editable supercapacitor was paired with a sensor and placed on the human elbow, it performed better than existing stretchable supercapacitors. The editable supercapacitor was able to provide a stable stream of signals even when the arm was swinging, which are then transmitted wirelessly to external devices, such as one that captures a patient’s heart rate.

The authors believe that the editable supercapacitor could be easily mass-produced as it would rely on existing manufacturing technologies. Production cost will thus be low, estimated at about SGD$0.13 (USD$0.10) to produce 1 cm2 of the material.

The team has filed a patent for the technology.

Professor Chen said, “A reliable and editable supercapacitor is important for development of the wearable electronics industry. It also opens up all sorts of possibilities in the realm of the ‘Internet-of-Things’ when wearable electronics can reliably power themselves and connect and communicate with appliances in the home and other environments.

“My own dream is to one day combine our flexible supercapacitors with wearable sensors for health and sports performance diagnostics. With the ability for wearable electronics to power themselves, you could imagine the day when we create a device that could be used to monitor a marathon runner during a race with great sensitivity, detecting signals from both under and over-exertion.”

The editable supercapacitor is made of strengthened manganese dioxide nanowire composite material. While manganese dioxide is a common material for supercapacitors, the ultralong nanowire structure, strengthened with a network of carbon nanotubes and nanocellulose fibres, allows the electrodes to withstand the associated strains during the customisation process.

The NTU team also collaborated with Dr. Loh Xian Jun, Senior Scientist and Head of the Soft Materials Department at the Institute of Materials Research and Engineering (IMRE), Agency for Science, Technology and Research (A*STAR).

Dr. Loh said, “Customisable and versatile, these interconnected, fabric-like power sources are able to offer a plug-and-play functionality while maintaining good performance. Being highly stretchable, these flexible power sources are promising next-generation ‘fabric’ energy storage devices that could be integrated into wearable electronics.”

Flexible Batteries Power the Future of Wearable Technology: U of Manchester


flexiblebattCredit: University of Manchester

The rapid development of wearable technology has received another boost from a new development using graphene for printed electronic devices.

New research from The University of Manchester has demonstrated flexible battery-like devices printed directly on to textiles using a simple screen-printing technique.

The current hurdle with wearable technology is how to power devices without the need for cumbersome battery packs. Devices known as supercapacitors are one way to achieve this. A  acts similarly to a battery but allows for rapid charging which can fully charge devices in seconds.

Now a solid-state flexible supercapacitor device has been demonstrated by using conductive -oxide ink to print onto cotton fabric. As reported in the journal 2-D Materials the printed electrodes exhibited excellent mechanical stability due to the strong interaction between the ink and textile substrate. Graphene-Ribbon-Developing-Flexible-Li-Ion-Battery

Further development of graphene-oxide printed supercapacitors could turn the vast potential of  into the norm. High-performance sportswear that monitors performance, embedded health-monitoring devices, lightweight military gear, new classes of  and even wearable computers are just some of the applications that could become available following further research and development.

To power these new wearable devices, the energy storage system must have reasonable mechanical flexibility in addition to high energy and power density, good operational safety, long cycling life and be low cost.

 Credit: University of Manchester

Dr Nazmul Karim, Knowledge Exchange Fellow, the National Graphene Institute and co-author of the paper said: “The development of graphene-based flexible textile supercapacitor using a simple and scalable printing technique is a significant step towards realising multifunctional next generation wearable e-textiles.”

“It will open up possibilities of making an environmental friendly and cost-effective smart e-textile that can store energy and monitor human activity and physiological condition at the same time”.

Graphene-oxide is a form of graphene which can be produced relatively cheaply in an ink-like solution. This solution can be applied to textiles to create supercapacitors which become part of the fabric itself.

Kaust wearablebattery1Dr Amor Abdelkader, also co-author of the paper said: “Textiles are some of the most flexible substrates, and for the first time, we printed a stable device that can store energy and be as flexible as cotton.

“The  is also washable, which makes it practically possible to use it for the future smart clothes. We believe this work will open the door for printing other types of devices on  using 2-D-materials inks.”

The University of Manchester is currently completing the construction of its second major graphene facility to complement the National Graphene Institute (NGI). Set to be completed 2018, the £60m Graphene Engineering Innovation Centre (GEIC) will be an international research and technology facility.

The GEIC will offer the UK the unique opportunity to establish a leading role in graphene and related two-dimensional materials. The GEIC will be primarily industry-led and focus on pilot production and characterisation.

 Explore further: Researchers develop simple way to fabricate micro-supercapacitors with high energy density

 

 

Nano-Engineered functional textiles are going to revolutionize the clothing that we wear.


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

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

Permethrin-releasing
textile net on a body suitSandy 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

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.

 

Schematic illustration of a wearable triboelectric nanogenerator

(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

 

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Quantum Dots of Iron Arranged on Boron Nitride Nanotubes (BNNTs) for Better Wearable Tech Without Semiconductors: “Iron Stepping Stones” with Video


Nanotube Iron QDs image131438-horiz

Iron-dotted boron nitride nanotubes, made in Yoke Khin Yaps’ lab at Michigan Tech, could make for better wearable tech because of their flexibility and electronic behaviors.

February 5, 2016—

The road to more versatile wearable technology is dotted with iron. Specifically, quantum dots of iron arranged on boron nitride nanotubes (BNNTs). The new material is the subject of a studypublished in Scientific Reports in February, led by Yoke Khin Yap, a professor of physics at Michigan Technological University.

Yap says the iron-studded BNNTs are pushing the boundaries of electronics hardware. The transistors modulating electron flow need an upgrade.

“Look beyond semiconductors,” he says, explaining that materials like silicon semiconductors tend to overheat, can only get so small and leak electric current. The key to revamping the fundamental base of transistors is creating a series of stepping-stones.

Quantum Dots

The nanotubes are the mainframe of this new material. BNNTs are great insulators and terrible at conducting electricity. While at first that seems like an odd choice for electronics, the insulating effect of BNNTs is crucial to prevent current leakage and overheating. Additionally, electron flow will only occur across the metal dots on the BNNTs.

In past research, Yap and his team used gold for quantum dots, placed along a BNNT in a tidy line. With enough energy potential, the electrons are repelled by the insulating BNNT and hopscotch from gold dot to gold dot. This electron movement is called quantum tunneling.

“Imagine this as a river, and there’s no bridge; it’s too big to hop over,” Yap says. “Now, picture having stepping stones across the river—you can cross over, but only when you have enough energy to do so.”

Nanotech for Wearable Electronics

Unlike with semiconductors, there is no classical resistance with quantum tunneling. No resistance means no heat. Plus, these materials are very small; the nanomaterials enable the transistors to shrink as well. An added bonus is that BNNTs are also quite flexible, a boon for wearable electronics.

“Here’s where the challenge comes in,” Yap says, holding up a pen to demonstrate. He gestures along the length of the pen, which mimics a straight BNNT, tapping out a line of quantum dots. “We have an array here to do quantum tunneling, but what if we want to bend the array to be flexible like a piece of wearable electronics?”

Yap sets down the pen and curls up his index finger: “And if I bend the dots, the distance between them changes—in doing so, we change the electronic behavior.”

Changing the behavior means that the quantum tunneling may not work. The solution is to get out of line: Yap and his team arranged a grid of quantum dots around the outside of the BNNT.

“This time we used iron instead of gold,” Yap adds, explaining that gold’s melting temperature was low for the process his team used. “And when we tested the material, the electrons distributed uniformly across the whole surface of the nanotubes.”

That means that instead of having a line of stepping stones, there are many different paths across the river, and an electron will jump to the nearest one. For future use in wearable electronics, the multiplicity of paths ensures electricity is moving from one riverbank to the next, one way or another. Using scanning tunneling microscopy inside a transmission electron microscope (STM-TEM), the team successfully bent the iron dot-coated BNNT while monitoring the electron flows. The electronic behaviors remain the same even when the BNNT was bent all the way up to 75 degrees.

Next Steps

Yap says that this experiment is a proof of concept. While the iron BNNT material shows promise, it’s not a full transistor yet, capable of modulating electron movement. Right now, it’s called a flexible tunneling channel.

“Next, we’ll put the BNNT and iron onto a bendable plastic substrate,” Yap says. “Then we’ll bend this substrate and watch where the electrons go.”

This experimental work is complemented by computer simulations by John Jaszczak, professor of physics, and Paul Bergstrom, professor of electrical and computer engineering.

Which route the electricity takes is hard to track, which will be the main challenge for the next experiment. But one direction is certain, Yap’s research is headed down a path to change the basic level of electronics and make wearable tech more adaptable.

Michigan Technological University (www.mtu.edu) is a leading public research university developing new technologies and preparing students to create the future for a prosperous and sustainable world. Michigan Tech offers more than 120 undergraduate and graduate degree programs in engineering; forest resources; computing; technology; business; economics; natural, physical and environmental sciences; arts; humanities; and social sciences.

ASU: Stretchable Battery could Power Future Wearable Devices, Smart Clothes: Video


Israeli 0422 flexible-screen-811x497Using a twist on the art of origami paper folding, a research team at Arizona State University has created batteries that would be ideal for watch bands and connected clothing.

A team of researchers at Arizona State University has created a battery that can stretch up to 150 percent, opening the door for embedded power packs in smartwatches, clothes and other devices.

The approach is based on kirigami — a twist on origami, or paper folding — that turns a solid battery into several smaller ones with various folds and cuts. The result? A battery that isn’t a small brick, but instead can twist, bend and stretch while still providing full power.

That could be the “killer application” for such batteries although there’s an obvious potential application in smartwatch bands. Wearable devices don’t actually have to be devices.

I’ve already tested a shirt — or biometric smartwear to be more precise — that measures my real time heart rate and respiration, for example.

The conductive fibers to do so are woven in to the shirt but they need power to transmit the data over Bluetooth to a mobile app. Currently, that power is found with the Bluetooth radio in a blocky, plastic module. Adding in a stretchable battery would reduce much of the module’s bulk and also provide flexibility for the garment to stretch.

While our biggest battery challenge is still the amount of power capacity we can store in a given space, ASU’s effort shows that we can still make some tweaks that could radically change the form of a battery; even in smart clothes.