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

 

 

Advertisements

Long-Term Health Monitoring Possible through Breathable, Wearable Electronics on Our Skin


Nano Skin breathablewe
The diagram at top illustrates the structure of gold nanomesh conductors laminated onto the skin surface. The nanomesh, constructed from polyvinyl alcohol (PVA) nanofibers and a gold (Au) layer, adheres to the skin when sprayed with water, …more

A hypoallergenic electronic sensor can be worn on the skin continuously for a week without discomfort, and is so light and thin that users forget they even have it on, says a Japanese group of scientists. The elastic electrode constructed of breathable nanoscale meshes holds promise for the development of noninvasive e-skin devices that can monitor a person’s health continuously over a long period.

Wearable electronics that monitor heart rate and other vital health signals have made headway in recent years, with next-generation gadgets employing lightweight, highly elastic materials attached directly onto the skin for more sensitive, precise measurements. However, although the  and rubber sheets used in these devices adhere and conform well to the skin, their lack of breathability is deemed unsafe for long-term use: dermatological tests show the fine, stretchable materials prevent sweating and block airflow around the skin, causing irritation and inflammation, which ultimately could lead to lasting physiological and psychological effects.

“We learned that devices that can be worn for a week or longer for continuous monitoring were needed for practical use in medical and sports applications,” says Professor Takao Someya at the University of Tokyo’s Graduate School of Engineering whose research group had previously developed an on-skin patch that measured oxygen in blood.

In the current research, the group developed an electrode constructed from nanoscale meshes containing a water-soluble polymer, polyvinyl alcohol (PVA), and a gold layer—materials considered safe and biologically compatible with the body. The  can be applied by spraying a tiny amount of water, which dissolves the PVA nanofibers and allows it to stick easily to the skin—it conformed seamlessly to curvilinear surfaces of human skin, such as sweat pores and the ridges of an index finger’s fingerprint pattern.

Breathable, wearable electronics on skin for long-term health monitoring
An array of nanomesh conductors attached to a fingertip, top, and a scanning electron microscope (SEM) image of a nanomesh conductor on a skin replica, bottom. Credit: 2017 Someya Laboratory.

The researchers next conducted a skin patch test on 20 subjects and detected no inflammation on the participants’  after they had worn the device for a week. The group also evaluated the permeability, with water vapor, of the nanomesh conductor—along with those of other substrates like ultrathin plastic foil and a thin rubber sheet—and found that its porous mesh structure exhibited superior gas permeability compared to that of the other materials.

Furthermore, the scientists proved the device’s mechanical durability through repeated bending and stretching, exceeding 10,000 times, of a conductor attached on the forefinger; they also established its reliability as an electrode for electromyogram recordings when its readings of the electrical activity of muscles were comparable to those obtained through conventional gel electrodes.

Breathable, wearable electronics on skin for long-term health monitoring
The electric current from a flexible battery placed near the knuckle flows through the conductor and powers the LED just below the fingernail. Credit: 2017 Someya Laboratory.

“It will become possible to monitor patients’ vital signs without causing any stress or discomfort,” says Someya about the future implications of the team’s research. In addition to nursing care and medical applications, the new device promises to enable continuous, precise monitoring of athletes’ physiological signals and bodily motion without impeding their training or performance.

 Explore further: Novel e-skin may monitor health, vital signs

More information: Akihito Miyamoto et al, Inflammation-free, gas-permeable, lightweight, stretchable on-skin electronics with nanomeshes, Nature Nanotechnology (2017). DOI: 10.1038/nnano.2017.125

 

Breakthrough in thin electrically conducting sheets paves way for smaller electronic devices



Through nanotechnology, physicists Dr Raymond McQuaid, Dr Amit Kumar and Professor Marty Gregg from Queen’s University’s School of Mathematics and Physics, have created unique 2-D sheets, called domain walls, which exist within crystalline materials.

The sheets are almost as thin as the wonder-material graphene, at just a few atomic layers. However, they can do something that graphene can’t – they can appear, disappear or move around within the crystal, without permanently altering the crystal itself.

This means that in future, even smaller electronic devices could be created, as electronic circuits could constantly reconfigure themselves to perform a number of tasks, rather than just having a sole function.
Professor Marty Gregg explains: “Almost all aspects of modern life such as communication, healthcare, finance and entertainment rely on microelectronic devices. 

The demand for more powerful, smaller technology keeps growing, meaning that the tiniest devices are now composed of just a few atoms – a tiny fraction of the width of human hair.”


Breakthrough in thin electrically conducting sheets paves way for smaller electronic devices Credit: Queen’s University Belfast

“As things currently stand, it will become impossible to make these devices any smaller – we will simply run out of space. This is a huge problem for the computing industry and new, radical, disruptive technologies are needed. One solution is to make electronic circuits more ‘flexible’ so that they can exist at one moment for one purpose, but can be completely reconfigured the next moment for another purpose.”

The team’s findings, which have been published in Nature Communications, pave the way for a completely new way of data processing.

Professor Gregg says: “Our research suggests the possibility to “etch-a-sketch” nanoscale electrical connections, where patterns of electrically conducting wires can be drawn and then wiped away again as often as required.

“In this way, complete electronic circuits could be created and then dynamically reconfigured when needed to carry out a different role, overturning the paradigm that electronic circuits need be fixed components of hardware, typically designed with a dedicated purpose in mind.”


Breakthrough in thin electrically conducting sheets paves way for smaller electronic devices Credit: Queen’s University Belfast

There are two key hurdles to overcome when creating these 2-D sheets, long straight walls need to be created. These need to effectively conduct electricity and mimic the behavior of real metallic wires. It is also essential to be able to choose exactly where and when the domain walls appear and to reposition or delete them.

 Through the research, the Queen’s researchers have discovered some solutions to the hurdles. Their research proves that long conducting sheets can be created by squeezing the crystal at precisely the location they are required, using a targeted acupuncture-like approach with a sharp needle. The sheets can then be moved around within the crystal using applied electric fields to position them.

Dr Raymond McQuaid, a recently appointed lecturer in the School of Mathematics and Physics at Queen’s University, added: “Our team has demonstrated for the first time that copper-chlorine boracite crystals can have straight conducting walls that are hundreds of microns in length and yet only nanometres thick. 

The key is that, when a needle is pressed into the crystal surface, a jigsaw puzzle-like pattern of structural variants, called “domains”, develops around the contact point. The different pieces of the pattern fit together in a unique way with the result that the conducting walls are found along certain boundaries where they meet.

“We have also shown that these walls can then be moved using applied electric fields, therefore suggesting compatibility with more conventional voltage operated devices. Taken together, these two results are a promising sign for the potential use of conducting walls in reconfigurable nano-electronics.”

 

More information: Raymond G.P. McQuaid et al. Injection and controlled motion of conducting domain walls in improper ferroelectric Cu-Cl boracite, Nature Communications (2017). DOI: 10.1038/ncomms15105

Provided by: Queen’s University Belfast

A New “Skin-Like” triboelectric Nanogenerator for Multifunction Power Sources and Wearable Electronics


Skin Tite China 59315af818740

A transparent electronic skin for tactile sensing. Credit: Xiong Pu

A team of researchers with the National Center for Nanoscience and Technology in China has developed what it is calling a skin-like triboelectric nanogenerator (STENG). In their paper published in the journal Science Advances, the group describes the nanogenerator they built and offer suggestions for its use.

 

Prior research led to the construction of TENG devices that generate electricity by pressing together and taking them apart, creating an . In this new effort, the researchers put an S in front of the name of their TENG device to highlight its similarity to .

To make the new device, the group mixed an elastomer with an ionic hydrogel to create a material that is both flexible and nearly transparent. Unlike other TENG devices, the elastomer can be used as the layer that is electrified while the hydrogel can work as the electrode. This allowed for much better stretching abilities—the team reports a 1000 percent improvement over other TENGs.

The researchers report that the material is also nearly clear, allowing 96.2 percent of light to pass through it—this, they suggest, makes it useful for devices that require transmission of optical data. The nanogenerator was able to continue functioning properly in temperatures up to 30° C, and with humidity as high as 30 percent. Testing showed that the material was capable of producing up to 145 volts and had a power density of 35 milliwatts per square meter when configured as an open circuit. The team notes also that all of the materials used to make the are inexpensive, light and readily available

 

More information: Ultrastretchable, transparent triboelectric nanogenerator as electronic skin for biomechanical energy harvesting and tactile sensing, Science Advances  31 May 2017: Vol. 3, no. 5, e1700015, DOI: 10.1126/sciadv.1700015

Abstract
Rapid advancements in stretchable and multifunctional electronics impose the challenge on corresponding power devices that they should have comparable stretchability and functionality. We report a soft skin-like triboelectric nanogenerator (STENG) that enables both biomechanical energy harvesting and tactile sensing by hybridizing elastomer and ionic hydrogel as the electrification layer and electrode, respectively.

Nano generator 59315b0222337

A circular soft and transparent triboelectric nanogenerator. Credit: Xiong Pu

For the first time, ultrahigh stretchability (uniaxial strain, 1160%) and transparency (average transmittance, 96.2% for visible light) are achieved simultaneously for an energy-harvesting device. The soft TENG is capable of outputting alternative electricity with an instantaneous peak power density of 35 mW m−2 and driving wearable electronics (for example, an electronic watch) with energy converted from human motions, whereas the STENG is pressure-sensitive, enabling its application as artificial electronic skin for touch/pressure perception.

Our work provides new opportunities for multifunctional power sources and potential applications in soft/wearable electronics.

 

UC San Diego: Printed, flexible and rechargeable battery can power Wearable Sensors, Solar Cells, Electronics


 

Nanoengineers at the University of California San Diego have developed the first printed battery that is flexible, stretchable and rechargeable. The zinc batteries could be used to power everything from wearable sensors to solar cells and other kinds of electronics.

The work appears in the April 19, 2017 issue of Advanced Energy Materials.

The researchers made the printed batteries flexible and stretchable by incorporating a hyper-elastic polymer material made from isoprene, one of the main ingredients in rubber, and polystyrene, a resin-like component. The substance, known as SIS, allows the batteries to stretch to twice their size, in any direction, without suffering damage.

The ink used to print the batteries is made of zinc silver oxide mixed with SIS. While zinc batteries have been in use for a long time, they are typically non-rechargeable. The researchers added bismuth oxide to the batteries to make them rechargeable.

“This is a significant step toward self-powered stretchable electronics,” said Joseph Wang, one of the paper’s senior authors and a nanoengineering professor at the Jacobs School of Engineering at UC San Diego, where he directs the school’s Center for Wearable Sensors. “We expect this technology to pave the way to enhance other forms of energy storage and printable, stretchable electronics, not just for zinc-based batteries but also for Lithium-ion batteries, as well as supercapacitors and photovoltaic cells.”

The prototype battery the researchers developed has about 1/5 the capacity of a rechargeable hearing aid battery. But it is 1/10 as thick, cheaper and uses commercially available materials. It takes two of these batteries to power a 3 Volt LED. The researchers are still working to improve the battery’s performance. Next steps include expanding the use of the technology to different applications, such as solar and fuel cells; and using the battery to power different kinds of electronic devices.

Researchers used standard screen printing techniques to make the batteries–a method that dramatically drives down the costs of the technology. Typical materials for one battery cost only $0.50. A comparable commercially available rechargeable battery costs $5.00 Batteries can be printed directly on fabric or on materials that allow wearables to adhere to the skin. They also can be printed as a strip, to power a device that needs more energy. They are stable and can be worn for a long period of time.

Making the batteries rechargeable

The key ingredient that makes the batteries rechargeable is a molecule called bismuth oxide which, when mixed into the batteries’ zinc electrodes, prolongs the life of devices and allows them to recharge. Adding bismuth oxide to zinc batteries is standard practice in industry to improve performance, but until recently, there hasn’t been a thorough scientific explanation for why.

Last year, UC San Diego nanoengineers led by Professor Y. Shirley Meng published a detailed molecular study addressing this question (download PDF here). When zinc batteries discharge, their electrodes react with the liquid electrolyte inside the battery, producing zinc salts that dissolve into a solution. This eventually short circuits the battery. Adding bismuth oxide keeps the electrode from losing zinc to the electrolyte. This ensures that the batteries continue to work and can be recharged.

The work shows that it is possible to use small amounts of additives, such as bismuth oxide, to change the properties of materials. “Understanding the scientific mechanism to do this will allow us to turn non-rechargeable batteries into rechargeable batteries—not just zinc batteries but also for other electro-chemistries, such as Lithium-oxygen,” said Meng, who directs the Sustainable Power and Energy Center at the UC San Diego Jacobs School of Engineering

From Innovation to Market

Rajan Kumar, a co-first author on this Advanced Energy Materials paper, is a nanoengineering Ph.D. student at the Jacobs School of Engineering. He and nanoengineering professor Wang are leading a team focused on commercializing aspects of this work. The team is one of five to be selected to join a new technology accelerator at UC San Diego. The technology accelerator is run by the UC San Diego Institute for the Global Entrepreneur, which is a collaboration between the Jacobs School of Engineering and Rady School of Management.

Kumar is excited at the prospect of taking advantage of all that the IGE Technology Accelerator has to offer.

“For us, it’s strategically perfect,” said Kumar, referring to the $50,000 funding for prototype improvements, the focus on prototype testing with a strategic partner, and the entrepreneurship mentoring.

Kumar is confident in the team’s innovations, which includes the ability to replace coin batteries with thin, stretchable batteries. Making the right strategic moves now is critical for commercialization success.

“It’s now about making sure our energies are focused in the right direction,” said Kumar.

In addition to the IGE Technology Accelerator, the team was also recently selected to participate in the NSF Innovation-Corps (I-Corps) program at UC San Diego, also administered by the Institute for the Global Entrepreneur. One of the key tenets of the I-Corps program is helping startup teams validate their target markets and business models early in the commercialization process. Through NSF I-Corps, for example, Kumar has already started interviewing potential customers which has helped the team better focus their commercialization strategy.

Through these programs, Kumar is focused on leading the team through a series of milestones in order to best position their innovations to refine “both what to build and who to build it for,” he said.

Paper Citation

“All-Printed, Stretchable Zn-Ag2O Rechargeable Battery via Hyperelastic Binder for Self-Powering Wearable Electronics” in the journal Advanced Energy Materials.http://onlinelibrary.wiley.com/doi/10.1002/aenm.201602096/full

Authors: Rajan Kumar, Jaewook Shin, Lu Yin, Jung-Min You, Prof. Shirley Meng and Prof. Joseph Wang, Department of Nanoengineering, Jacobs School of Engineering, University of California San Diego.

Joseph Wang is a distinguished professor, holds the SAIC endowed chair, and serves as chair of the Department of NanoEngineering at the UC San Diego Jacobs School of Engineering where he directs the Center for Wearable Sensors.

Shirley Meng is a professor in the Department of NanoEngineering and Director of the Sustainable Power and Energy Center at the UC San Diego Jacobs School of Engineering.

Research funders include: Advanced Research Projects Agency-Energy (DE-AR0000535); Rajan Kumar acknowledges the U.S. National Science Foundation (NSF) Graduate Research Fellowship under Grant No (DGE-1144086).

This work was performed in part at the San Diego Nanotechnology Infrastructure (SDNI), a member of the National Nanotechnology Coordinated Infrastructure, which is supported by the U.S. National Science Foundation (NSF).

Gold foil discovery could lead to wearable technology – Flexibility is the Key


goldfoildiscAn example of a gold foil peeled from single crystal silicon. Credit: Reprinted with permission from Naveen Mahenderkar et al., Science [355]:[1203] (2017).

Some day, your smartphone might completely conform to your wrist, and when it does, it might be covered in pure gold, thanks to researchers at Missouri University of Science and Technology.

Writing in the March 17 issue of the journal Science, the Missouri S&T researchers say they have developed a way to “grow” thin layers of gold on single crystal wafers of silicon, remove the gold foils, and use them as substrates on which to grow other electronic materials.

wearable-textiles-100616-0414_powdes_ti_f1The research team’s discovery could revolutionize wearable or “flexible” technology research, greatly improving the versatility of such electronics in the future.

According to lead researcher Dr. Jay A. Switzer, the majority of research into wearable technology has been done using polymer substrates, or substrates made up of multiple crystals. “And then they put some typically organic semiconductor on there that ends up being flexible, but you lose the order that (silicon) has,” says Switzer, Donald L. Castleman/FCR Endowed Professor of Discovery in Chemistry at S&T.

Because the polymer substrates are made up of multiple crystals, they have what are called , says Switzer. These grain boundaries can greatly limit the performance of an electronic device.

“Say you’re making a solar cell or an LED,” he says. “In a semiconductor, you have electrons and you have holes, which are the opposite of electrons. They can combine at grain boundaries and give off heat. And then you end up losing the light that you get out of an LED, or the current or voltage that you might get out of a solar cell.”

Most electronics on the market are made of silicon because it’s “relatively cheap, but also highly ordered,” Switzer says.

“99.99 percent of electronics are made out of silicon, and there’s a reason – it works great,” he says. “It’s a single crystal, and the atoms are perfectly aligned. But, when you have a single crystal like that, typically, it’s not flexible.”

By starting with single crystal silicon and growing gold foils on it, Switzer is able to keep the high order of silicon on the foil. But because the foil is gold, it’s also highly durable and flexible.

“We bent it 4,000 times, and basically the resistance didn’t change,” he says.

The gold foils are also essentially transparent because they are so thin. According to Switzer, his team has peeled foils as thin as seven nanometers.

Switzer says the challenge his research team faced was not in growing gold on the single crystal silicon, but getting it to peel off as such a thin layer of foil. Gold typically bonds very well to silicon.

“So we came up with this trick where we could photo-electrochemically oxidize the silicon,” Switzer says. “And the gold just slides off.”

Photoelectrochemical oxidation is the process by which light enables a semiconductor material, in this case silicon, to promote a catalytic oxidation reaction.

Switzer says thousands of gold foils—or foils of any number of other metals—can be made from a single crystal wafer of .

The research team’s discovery can be considered a “happy accident.” Switzer says they were looking for a cheap way to make single crystals when they discovered this process.

“This is something that I think a lot of people who are interested in working with highly ordered materials like single crystals would appreciate making really easily,” he says. “Besides making flexible devices, it’s just going to open up a field for anybody who wants to work with .”

Explore further: ‘Nanospears’ could lead to better solar cells, lasers, lighting

More information: Naveen K. Mahenderkar et al. Epitaxial lift-off of electrodeposited single-crystal gold foils for flexible electronics, Science (2017). DOI: 10.1126/science.aam5830

Read more at: https://phys.org/news/2017-03-gold-foil-discovery-wearable-technology.html#jCp

Read more at: https://phys.org/news/2017-03-gold-foil-discovery-wearable-technology.html#jCp

Environmentally-friendly graphene textiles could enable wearable electronics


graphene-textiles-19-environmenta

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. img_0801

“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.”

The work done by Dr Torrisi and Prof Wang, together with students Tian Carey and Jiesheng Ren, opens a number of commercial opportunities for graphene-based inks, ranging from personal health technology, high-performance sportswear, military garments, wearable technology/computing and fashion.
Electron microscopy image of a conductive graphene/cotton fabric. Credit: Jiesheng Ren
Environmentally-friendly graphene textiles could enable wearable electronics

 

“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 , 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 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- 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.

Explore further: New study shows nickel graphene can be tuned for optimal fracture strength

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

 

Nanotechnology in Smart Textiles and Wearables



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).

 


Genesis Nanotechnology Inc.

“Great Things from Small Things”

Watch Our YouTube Video:



WEARABLE NANOTECHNOLOGY ~ Imagine Charging Your Phone by “Plugging it Into Your Jacket” …


wearable-1-img_5629

Imagine plugging your phone into your jacket to charge it up or recharging your electric car just by leaving it in a sunny parking lot.

Associate Professor Jayan Thomas teaches nanotechnology at the University of Central Florida. He is working on a filament that can store the energy of the sun and could one day be woven into clothing or coat the roof of a car.wearable-textiles-100616-0414_powdes_ti_f1

To demonstrate how his project might work, Thomas had to learn how to use some old technology – a loom.

“Listen-In” to the Audio Link Below

 

Graphene Holds Great Promise for Electronics Applications – Wearable Electronics


mit-graphene-ii-shutterstock_62457640-610x406

Applications that have really spurred a huge amount of graphene and other two-dimensional (2D) material research over the years have come from the field of electronics. The fear that complementary metal–oxide–semiconductor (CMOS) technology is quickly nearing the end of its ability to ward off Moore’s Law, in which the number of transistors in a dense integrated circuit doubles approximately every two years, has been the spur for much graphene research.

However, there has always been the big problem for graphene that it does not have an intrinsic band gap. It’s a pure conductor and not a semiconductor, like silicon, capable turning on and off the flow of electrons through it. While graphene can be functionalized in a way that it does have a band gap, research for it in the field of electronics have looked outside of digital logic where an intrinsic band gap is such an advantage.

In the stories below, we see how graphene’s unrivaled conductivity is being exploited to take advantage of its strengths rather than trying to cover up for its weaknesses.

Graphene Comes to the Rescue of Li-ion Batteries

The role of graphene in increasing the charge capacity of the electrodes in lithium-ion (Li-ion) batteries has varied. There’s been “decorated graphene” in which nanoparticles are scattered across the surface of the graphene, and graphene nanoribbons, just to name a few of the avenues that have been pursued.

Another way in which graphene has been looked at is to better enable silicon to serve as the electrode material for Li-ion batteries. Silicon is a great material for increasing the storage capacity of electrodes in Li-ion batteries, but there’s one big problem: it cracks after just few charge/discharge cycles. The aim has been to find a way to make silicon so that it’s not so brittle and can withstand the swelling and shrinking during the charge charging and discharing of lithium atoms into the electrode material In these efforts, like those out Northwestern University, the role of graphene has been to sandwich silicon between layers graphene sheets in the anode of the battery.

Now, Yi Cui from both Stanford University and the Department of Energy’s SLAC National Accelerator Laboratory, who has been at the forefront of research to get silicon to be more flexible and durable for Li-ion batteries, has turned to graphene to solve the issue.

Cui and his colleagues were able to demonstrate in research described in the journal Nature Energy, a method for to encasing each particle of silicon in a cage of graphene that enables the silicon to expand and contract without cracking. In a full-cell electrochemical test, the graphene-infused silicon anodes retained 90 percent of their charge capacity after 100 charge-discharge cycles.

Previous attempts by Cui and many others to create nanostructured silicon has been very difficult, making mass production fairly impractical. However, based on these latest results, Cui believes that this approach is not only technologically possible, but may in fact be commercially viable.

The process involves coating the silicon particles with a layer of nickel. The nickel coating is used as the surface and the catalyst for the second step: growing the graphene. The final step of the process involves using an acid on the graphene-coated silicon particles so that the nickel is etched away.

“This new method allows us to use much larger silicon particles that are one to three microns, or millionths of a meter, in diameter, which are cheap and widely available,” Cui said in a press release. “Particles this big have never performed well in battery anodes before, so this is a very exciting new achievement, and we think it offers a practical solution.”

While a practical manufacturing approach was much needed, the technique also leads to an electrode material with very high charge capacity.

“Researchers have tried a number of other coatings for silicon anodes, but they all reduced the anode’s efficiency,” said Stanford postdoctoral researcher Kai Yan, in a press release. “The form-fitting graphene cages are the first coating that maintains high efficiency, and the reactions can be carried out at relatively low temperatures.”

Graphene Provides the Perfect Touch to Flexible Sensors

 

Photo: Someya Laboratory

Flexible sensors are the technological backbone of artificial skin technologies. The idea is that you can impart the sense of touch to a flexible sensor, making it possible to cover a prosthetic device for either a robot or replacement limb so it can feel. Creating materials that tick the boxes of flexibility, durability and sensitivity has been a challenge. Over the years, researchers have increasingly turned to nanomaterials, and graphene in particular, as a possible solution.

Researchers at the University of Tokyo have found that nanofibers produced from a combination of carbon nanotubes and graphene overcomes some of the big problems facing flexible pressure sensors: they’re not that accurate after being bent or deformed. The researchers have suggested that the flexible sensor they have developed could provide a more accurate detection breast cancer.

In research described in the journal Nature Nanotechnology, the scientists produced their flexible sensor by employing organic transistors and a pressure sensitive nanofiber structure.

The researchers constructed the nanofiber structure using nanofibers with diameters ranging between 300 to 700 nanometers. The researchers produced the nanofibers by combining carbon nanotubes and graphene and mixing that into a flexible polymer. The nanofibers entangled with each other to form a thin, transparent structure.

In contrast to other flexible sensors in which the striving for accuracy makes the sensors too sensitive to being deformed in any way, the fibers in this new flexible sensor does not lose their accuracy in measuring pressures. These fibers achieve this because of their ability to change their relative alignment to accommodate the bending. This allows them to continue measuring pressure because it reduces the strain in individual fibers.

Tunable Graphene Plasmons Lead to Tunable Lasers

Illustration: University of Manchester

A few years ago, researchers found that the phenomenon that occurs when photons strike a metallic surface and stir up the movement of electrons on the surface to the point where the electrons form into waves—known as surface plasmons—also occurs in graphene.

This discovery along with the ability to tune the graphene plasmons has been a big boon for the use of graphene in optoelectronic applications.  Now research out of the University of Manchester, led by Konstantin Novoselov, who along with Andre Geim were the two University of Manchester scientists who won the Nobel Prize for discovering graphene, has leveraged the ability of tuning graphene plasmons and combined it with terahertz quantum cascade lasers, making it possible to reversibly alter their emission.

This ability to reversibly the alter the emission of quantum cascade lasers is a big deal in optoelectronic applicatiopns, such as fiber optics telecommunication technologies by offering potentially higher bandwidth capabilities.

“Current terahertz devices do not allow for tunable properties, a new device would have to be made each time requirements changed, making them unattractive on an industrial scale,” said Novoselov in a press release. “Graphene however, can allow for terahertz devices to be switched on and off, as well as altering their state.”

In research described in the journal Science, were able to manipulate the doping levels of a graphene sheet so that it generated plasmons on its surface. When this doped graphene sheet was combined with a terahertz quantum cascade laser, it became possible to tune the transmission of the laser by tuning the graphene plasmons, essentially changing the concentration of charge carriers.

Graphene Flakes Speed Up Artificial Brains

Illustration: Alexey Kotelnikov/Alamy
Researchers out of Princeton University have found that graphene flakes could be a key feature in computer chips that aim at mimicking the function of the human brain.
In the human brain, neurons are used to transmit information by passing electrical charges through them. In artificial brains, transistors would take the place of neurons. One approach has been to construct the transistors out of lasers that would turn and off and the time intervals between the on and off states of the lasers would represent the 1s and 0s of digital logic.

One of the challenges that researchers have faced in this design is getting the time intervals between the laser pulses down to picosecond time scales, one trillionth of a second.

In research described in the journal Nature Scientific Reports, the Princeton researchers placed graphene flakes inside a semiconductor laser to act as a kind of “saturable absorber,” that absorbed photons and then was able to emit them in a quick burst.

It turns out graphene possesses a number of properties that makes it attractive for this application. Not only can it absorb and release photons extremely quickly, but it can also work at any wavelength. What this means is that even if semiconductor lasers are emitting different colors, the graphene makes it possible for them to work together simultaneously without interfering with each other, leading to higher processing speeds.

Posted By Terrance Barkan