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

 

 

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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.