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A new, electronic skin microsystem tracks heart rate, respiration, muscle movement and other health data, and wirelessly transmits it to a smartphone. The electronic skin offers several improvements over existing trackers, including greater flexibility, smaller size, and the ability to stick the self-adhesive patch -- which is a very soft silicone about four centimeters (1.5 inches) in diameter -- just about anywhere on the body. （A research team led by Professor Kyung-In Jang of Robotics Engineering collects, analyzes, and diagnoses bio-signals wirelessly transmitted to mobile application from the soft electronic skin.）   The microsystem was developed by an international team led by Kyung-In Jang, a professor of robotics engineering at South Korea's Daegu Gyeongbuk Institute of Science and Technology, and John A. Rogers, the director of Northwestern University's Center for Bio-Integrated Electronics. The team described the new device in the journal Nature Communications.   The electronic skin contains about 50 components connected by a network of 250 tiny wire coils embedded in protective silicone. The soft material enables it to conform to body, unlike other hard monitors. It wirelessly transmits data on movement and respiration, as well as electrical activity in the heart, muscles, eyes and brain to a smartphone application.   Unlike flat sensors, the tiny wires coils in this device are three-dimensional, which maximizes flexibility. The coils can stretch and contract like a spring without breaking. The coils and sensor components are also configured in an unusual spider web pattern that ensures "uniform and extreme levels of stretchability and bendability in any direction." It also enables tighter packing of components, minimizing size. The researchers liken the design to a winding, curling vine, connecting sensors, circuits and radios like individual leaves on the vine.   The key to creating this novel microsystem is stretching the elastic silicone base while the tiny wire arcs, made of gold, chromium and phosphate, are laid flat onto it. The arcs are firmly connected to the base only at one end of each arc. When the base is allowed to contract, the arcs pop up, forming three-dimensional coils.   The entire system is powered wirelessly rather than being charged by a battery. The researchers also considered key electrical and mechanical issues to optimize the system's physical layout, such as sensor placement or wire length, to minimize signal interference and noise.   The electronic skin could be used in a variety of applications, including continuous health monitoring and disease treatment. Professor Jang states "Combining big data and artificial intelligence technologies, the wireless biosensors can be developed into an entire medical system which allows portable access to collection, storage, and analysis of health signals and information." He added "We will continue further studies to develop electronic skins which can support interactive telemedicine and treatment systems for patients in blind areas for medical services such as rural houses in mountain village." The microsystem could also be used in other areas of emerging interest, such as soft robotics or autonomous navigation, which the team is now investigating.   Ref. KY32-AD22050RZ KY32-AD9945KCPZ

Good things come in small packages. This is especially true in the world of portable wireless communications systems. Cell phones, wearables, and implantable electronics have shrunk over time, which has made them more useful in many cases. But a critical component of these devices -- the antenna -- hasn't followed suit. Researchers haven't been able to get them much smaller, until now. In a paper published online Tuesday in Nature Communications, Nian Sun, professor of electrical and computer engineering at Northeastern, and his colleagues describe a new approach to designing antennas. The discovery enables researchers to construct antennas that are up to a thousand times smaller than currently available antennas, Sun said. "A lot of people have tried hard to reduce the size of antennas. This has been an open challenge for the whole society," Sun said. "We looked into this problem and thought, 'why don't we use a new mechanism?'" Traditional antennas are built to receive and transmit electromagnetic waves, which travel fast -- up to the speed of light. But electromagnetic waves have a relatively long wavelength. That means antennas must maintain a certain size in order to work efficiently with electromagnetic radiation. Instead of designing antennas at the electromagnetic wave resonance -- so they receive and transmit electromagnetic waves -- researchers tailored the antennas to acoustic resonance. Acoustic resonance waves are roughly 10 thousand times -- smaller than electromagnetic waves. This translates to an antenna that's one or two orders of magnitude smaller than even the most compact antennas available today. Since acoustic resonance and electromagnetic waves have the same frequency, the new antennas would still work for cell phones and other wireless communication devices. And they would provide the same instantaneous delivery of information. In fact, researchers found their antennas performed better than traditional kinds. Tiny antennas have big implications, especially for Internet of Things devices, and in the biomedical field. For example, Sun said the technology could lead to better bioinjectible, bioimplantable, or even bioinjestible devices that monitor health. One such application that neurosurgeons are interested in exploring is a device that could sense neuron behavior deep in the brain. But bringing this idea to life has stumped researchers, until now. "Something that's millimeters or even micrometers in size would make biomedical implantation much easier to achieve, and the tissue damage would be much less," Sun said. Ref.KY78-501WPKY78-ASM56

In autumn, an abundance of fallen leaves from deciduous phoenix trees are scattered around the streets in Northern China. These leaves are generally burned in the colder season, exacerbating the country's air pollution problem.Investigators in Shandong, China, recently discovered a new method to convert this organic waste matter into a porous carbon material that can be used to produce high-tech electronics. The advance is reported in the Journal of Renewable and Sustainable Energy, by AIP Publishing. The investigators used a multistep, yet simple, process to convert tree leaves into a form that could be incorporated into electrodes as active materials. The dried leaves were first ground into a powder, then heated to 220 degrees Celsius for 12 hours. This produced a powder composed of tiny carbon microspheres. These microspheres were then treated with a solution of potassium hydroxide and heated by increasing the temperature in a series of jumps from 450 to 800 C. The chemical treatment corrodes the surface of the carbon microspheres, making them extremely porous. The final product, a black carbon powder, has a very high surface area due to the presence of many tiny pores that have been chemically etched on the surface of the microspheres. The high surface area gives the final product its extraordinary electrical properties.(Scanning Electron Microscopy (SEM) image of porous carbon microspheres.)The investigators ran a series of standard electrochemical tests on the porous microspheres to quantify their potential for use in electronic devices. The current-voltage curves for these materials indicate that the substance could make an excellent capacitor. Further tests show that the materials are, in fact, supercapacitors, with specific capacitances of 367 Farads/gram, which are over three times higher than values seen in some graphene supercapacitors. A capacitor is a widely used electrical component that stores energy by holding a charge on two conductors, separated from each other by an insulator. Supercapacitors can typically store 10-100 times as much energy as an ordinary capacitor, and can accept and deliver charges much faster than a typical rechargeable battery. For these reasons, supercapacitive materials hold great promise for a wide variety of energy storage needs, particularly in computer technology and hybrid or electric vehicles. This research is led by Hongfang Ma of Qilu University of Technology, and has been heavily focused on looking for ways to convert waste biomass into porous carbon materials that can be used in energy storage technology. In addition to tree leaves, the team and others have successfully converted potato waste, corn straw, pine wood, rice straw and other agricultural wastes into carbon electrode materials. Professor Ma and her colleagues hope to improve even further on the electrochemical properties of porous carbon materials by optimizing the preparation process and allowing for doping or modification of the raw materials. The supercapacitive properties of the porous carbon microspheres made from phoenix tree leaves are higher than those reported for carbon powders derived from other biowaste materials. The fine scale porous structure seems to be key to this property, since it facilitates contact between electrolyte ions and the surface of the carbon spheres, as well as enhancing ion transfer and diffusion on the carbon surface. The investigators hope to improve even further on these electrochemical properties by optimizing their process and allowing for doping or modification of the raw materials.  This article is authored by Hongfang Ma, Zhibao Liu, Xiaodan Wang and Rongyan Jiang and is published in Journal of Renewable and Sustainable Energy.  Ref.KY36-5KK560KOAAM(capacitor)KY36-DEBB33F222KA3B(capacitor)KY605-NH12VP(rechargeable battery)  

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 supercapacitor 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 graphene-oxide ink to print onto cotton fabric. As reported in the journal 2D Materials the printed electrodes exhibited excellent mechanical stability due to the strong interaction between the ink and textile substrate. Further development of graphene-oxide printed supercapacitors could turn the vast potential of wearable technology into the norm. High-performance sportswear that monitors performance, embedded health-monitoring devices, lightweight military gear, new classes of mobile communication devices 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. 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. Dr 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 device 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 textile using 2D-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 2D materials. The GEIC will be primarily industry-led and focus on pilot production and characterisation. Ref.MS614SE-FL28EML-614S/FN

As we can know, a new technique that can change plastic's molecular structure to help it cast off heat is a promising step in that direction. Advanced plastics could usher in lighter, cheaper, more energy-efficient product components, including those used in vehicles, LEDs and computers -- if only they were better at dissipating heat. Developed by a team of University of Michigan researchers in materials science and mechanical engineering and detailed in a new study published in Sciene Advances, the process is inexpensive and scalable. The concept can likely be adapted to a variety of other plastics. In preliminary tests, it made a polymer about as thermally conductive as glass -- still far less so than metals or ceramics, but six times better at dissipating heat than the same polymer without the treatment."Plastics are replacing metals and ceramics in many places, but they're such poor heat conductors that nobody even considers them for applications that require heat to be dissipated efficiently," said Jinsang Kim, U-M materials science and engineering professor. "We're working to change that by applying thermal engineering to plastics in a way that hasn't been done before." The process is a major departure from previous approaches, which have focused on adding metallic or ceramic fillers to plastics. This has met with limited success; a large amount of fillers must be added, which is expensive and can change the properties of the plastic in undesirable ways. Instead, the new technique uses a process that engineers the structure of the material itself. Plastics are made of long chains of molecules that are tightly coiled and tangled like a bowl of spaghetti. As heat travels through the material, it must travel along and between these chains -- an arduous, roundabout journey that impedes its progress. The team -- which also includes U-M associate professor of mechanical engineering Kevin Pipe, mechanical engineering graduate researcher Chen Li and materials science and engineering graduate student Apoorv Shanker -- used a chemical process to expand and straighten the molecule chains. This gave heat energy a more direct route through the material. To accomplish this, they started with a typical polymer, or plastic. They first dissolved the polymer in water, then added electrolytes to the solution to raise its pH, making it alkaline. The individual links in the polymer chain -- called monomers -- take on a negative charge, which causes them to repel each other. As they spread apart, they unfurl the chain's tight coils. Finally, the water and polymer solution is sprayed onto plates using a common industrial process called spin casting, which reconstitutes it into a solid plastic film. The uncoiled molecule chains within the plastic make it easier for heat to travel through it. The team also found that the process has a secondary benefit -- it stiffens the polymer chains and helps them pack together more tightly, making them even more thermally conductive. "Polymer molecules conduct heat by vibrating, and a stiffer molecule chain can vibrate more easily," Shanker said. "Think of a tightly stretched guitar string compared to a loosely coiled piece of twine. The guitar string will vibrate when plucked, the twine won't. Polymer molecule chains behave in a similar way." Pipe says that the work can have important consequences because of the large number of polymer applications in which temperature is important. "Researchers have long studied ways to modify the molecular structure of polymers to engineer their mechanical, optical or electronic properties, but very few studies have examined molecular design approaches to engineer their thermal properties," Pipe said. "While heat flow in materials is often a complex process, even small improvements in the thermal conductivities of polymers can have a large technological impact." The team is now looking at making composites that combine the new technique with several other heat dissipating strategies to further increase thermal conductivity. They're also working to apply the concept to other types of polymers beyond those used in this research. A commercial product is likely several years away. "We're looking at using organic solvents to apply this technique to non- water soluble polymers," Li said. "But we believe that the concept of using electrolytes to thermally engineer polymers is a versatile idea that will apply across many other materials." Ref.KY59-GW5BTF50K00KY59-LMR040-0700-40F8-20100EW

Washington State University physicists have found a way to write an electrical circuit into a crystal, opening up the possibility of transparent, three-dimensional electronics that, like an Etch A Sketch, can be erased and reconfigured. The work, to appear in the on-line journal Scientific Reports, serves as a proof of concept for a phenomenon that WSU researchers first discovered by accident four years ago. At the time, a doctoral student found a 400-fold increase in the electrical conductivity of a crystal simply by leaving it exposed to light. Matt McCluskey, a WSU professor of physics and materials science, has now used a laser to etch a line in the crystal. With electrical contacts at each end of the line, it carried a current. "It opens up a new type of electronics where you can define a circuit optically and then erase it and define a new one," said McCluskey. "It's exciting that it's reconfigurable. It's also transparent. There are certain applications where it would be neat to have a circuit that is on a window or something like that, where it actually is invisible electronics." Ordinarily, a crystal does not conduct electricity. But when the crystal strontium titanate is heated under the right conductions, it is altered so light will make it conductive. The phenomenon, called "persistent photoconductivity," also occurs at room temperature, an improvement over materials that require cooling with liquid nitrogen. "We're still trying to figure out exactly what happens," said McCluskey. He surmises that heat forces strontium atoms to leave the material, creating light-sensitive defects responsible for the persistent photoconductivity. McCluskey's recent work increased the crystal's conductivity 1,000-fold. The phenomenon can last up to a year. "We look at samples that we exposed to light a year ago and they're still conducting," said McCluskey. "It may not retain 100 percent of its conductivity, but it's pretty big." Moreover, the circuit can be by erased by heating it on a hot plate and recast with an optical pen. "It's an Etch A Sketch," said McCluskey. "We've done it a few cycles. Another engineering challenge would be to do that thousands of times." The research was funded by the National Science Foundation. Co-authors on the paper are former students Violet Poole and Slade Jokela. The work is in keeping with WSU's Grand Challenges, a suite of initiatives aimed at addressing large societal problems. It is particularly relevant to the challenge of Smart Systems and its theme of foundational and emergent materials. Ref.KY163-NX1255GBKY163-TSX-3225