How energy harvesting tech could power wearables and the internet of things

(GigaOm) It’s all very well talking about the evolution of wearable computing and the internet of things, but something has to power these thin and/or tiny devices. For that reason, it’s a good thing that so many ideas are popping up in the field of energy harvesting and storage. Some of these ideas were on display this week at the Printed Electronics Europe 2013 event in Berlin, which took in a variety of sub-events including the Energy Harvesting & Storage Europe show. The concepts ranged from the practical to the experimental, so let’s start with the practical.

S.D. School of Mines: Generating sustainable hydrogen energy goal of splitting water molecules

Finding a way to exponentially double the hydrogen atoms to create a sustainable amount of hydrogen regeneration so that a new form of energy can be harvested is the ultimate goal of researchers at the South Dakota School of Mines & Technology. Rajesh Shende, PhD, and Jan Puszynski, PhD, of the Department of Chemical and Biological Engineering, have been awarded a $299,975 NSF three-year grant to test high-temperature water splitting in multiple thermochemical cycles. Using thermally-stabilized redox materials, particularly ferrites, already the team has documented reliable multiple-cycle results, sparking hope that sustainable hydrogen energy through the use of thermal hydro-splitting will one day be feasible, says Shende. Just two other US. locations, and possibly a third, are conducting similar research, according to Shende. One of the aspects that makes the Mines experiments unique is that the group has successfully split water molecules during multiple cycles at significantly lower temperatures than other documented research efforts. While others have demonstrated thermochemical splitting at 800-1,500°C, the School of Mines has documented multiple cycles at 700-1,100°C, which could potentially lead to a more affordable large-scale effort.

Mainz scientists create new flexible mineral inspired by deep-sea sponges

(YouTube) Scientists at Johannes Gutenberg University Mainz and the Max Planck Institute for Polymer Research in Germany have created a new synthetic hybrid material with a mineral content of almost 90 percent, yet extremely flexible. They imitated the structural elements found in most sea sponges and recreated the sponge spicules using the natural mineral calcium carbonate and a protein of the sponge. Natural minerals are usually very hard and prickly, as fragile as porcelain. Amazingly, the synthetic spicules are superior to their natural counterparts in terms of flexibility, exhibiting a rubber-like flexibility. The synthetic spicules can, for example, easily be U-shaped without breaking or showing any signs of fracture. This highly unusual characteristic, described by the German researchers in the current issue of Science, is mainly due to the part of organic substances in the new hybrid material. It is about ten times as much as in natural spicules. The synthetic material was self-assembled from an amorphous calcium carbonate intermediate and silicatein and subsequently aged to the final crystalline material. After six months, the synthetic spicules consisted of calcite nanocrystals aligned in a brick wall fashion with the protein embedded like cement in the boundaries between the calcite nanocrystals.

BBC: The ceramic used in bullet-stopping body armor

Ceramics could be the key to providing soldiers with lighter and more effective body armor, according to a British research team attracting interest from the Ministry of Defense. “Most people are familiar with ceramics in the house—your plates, mugs and possibly your toilet,” says material scientist Hywel Jones of Sheffield Hallam University. The ceramics he hopes to use in body armor are in some ways similar being hard, light and brittle, but they are specialized versions known as engineering or technical ceramics. Jones is working with Anthony Pick, a ceramics consultant to develop new armor materials. The work is being carried out by XeraCarb, a spin-out business created by Sheffield Hallam to take its technology into production. They have produced a low-density composite ceramic which is mainly silicon carbide. Its manufacture requires lower furnace temperatures than similar materials, making it more energy efficient and cheaper to produce.

Novel heating system could Improve electric car’s range: Prototype system can heat and cool without draining battery power.

(MIT Technology Review) Buyers considering an electric car must bear in mind that using battery-powered heating and air conditioning can decrease the car’s range by a third or more. But, a heating and cooling system being developed by researchers at MIT almost eliminates the drain on the battery. The researchers are working with Ford on a system that they hope to test in Ford’s Focus EV within the next two years. The work is being funded with a $2.7 million grant from the ARPA-E. The researchers describe their new device as a thermal battery. It uses materials that can store large amounts of coolant in a small volume. As the coolant moves through the system, it can be used for either heating or cooling. In the system, water is pumped into a low-pressure container, evaporating and absorbing heat in the process. The water vapor is then exposed to an adsorbant—a material with microscopic pores that have an affinity for water molecules. This material pulls the vapor out of the container, keeping the pressure low so more water can be pumped in and evaporated. This evaporative cooling process can be used to cool off the passenger compartment. As the material adsorbs water molecules, heat is released; it can be run through a radiator and dissipated into the atmosphere when the system is used for cooling, or it can be used to warm up the passenger compartment. The system requires very little electricity-just enough to run a small pump and fans to blow cool or warm air. Eventually the adsorbant can’t take in any more water, but the system can be “recharged” by heating the adsorbant above 200°C. This causes it to release the water, which is condensed and returned to a reservoir.

A look back: Four years with Dr. Chu

In honor of DOE Secretary Chu’s last day at the department, here’s a look back at his time overseeing important investments in science, innovation, and clean energy technologies that are making America more competitive and helping us win the race for a clean energy future. For more than four years, he has provided remarkable leadership in pursuing both President Obama’s nuclear security agenda as well as an all-of-the-above approach to energy that invests in clean energy, reduces our dependence on foreign oil, addresses the global climate crisis, and supports the clean energy jobs of the future.

2D germanium: Redesigned material could lead to lighter, faster electronics

The same material that formed the first primitive transistors more than 60 years ago can be modified in a new way to advance future electronics, according to a new study. Chemists at Ohio State University have developed the technology for making a one-atom-thick sheet of germanium, and found that it conducts electrons more than ten times faster than silicon and five times faster than conventional germanium. The material’s structure is closely related to that of graphene—a much-touted two-dimensional material comprised of single layers of carbon atoms. As such, graphene shows unique properties compared to its more common multilayered counterpart, graphite. Graphene has yet to be used commercially, but experts have suggested that it could one day form faster computer chips, and maybe even function as a superconductor, so many labs are working to develop it. Joshua Goldberger, assistant professor of chemistry at Ohio State, decided to take a different direction and focus on more traditional materials.In a paper published online in ACS Nano, he and his colleagues describe how they were able to create a stable, single layer of germanium atoms. In this form, the crystalline material is called germanane. Researchers have tried to create germanane before. This is the first time anyone has succeeded at growing sufficient quantities of it to measure the material’s properties in detail, and demonstrate that it is stable when exposed to air and water.

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Onyx: A brand new colorful source of energy

Onyx Solar has rolled out a complete new full range of colored photovoltaic glass. The new product, which allows any sustainable project to configure a customized design in any color (or combination of colors) while generating clean and free energy. The wide range of tones and colors provides to any architectural design-curtain wall, brise soleil, skylight, ventilated façade, canopy, etc.—a new world of possibilities to integrate photovoltaic materials into buildings. With this innovative product, Onyx Solar shows that implementing green building solutions is compatible with an aesthetic architectural design and gives an absolute freedom of choice to integrate renewable energy into buildings. In addition to energy generation, Onyx Solar multifunctional solutions also provide other benefits to the buildings that incorporate them: Provide both thermal and sound insulation and filter out harmful radiations of natural light (IR & UV).

Chinese ceramics hurt Indian manufacturers: Assocham study

Chinese ceramic products are flooding the Indian market that has been impacting the interest of domestic manufacturers to the extent that many small units are on the verge of closure, an Assocham study has said. Ceramics manufacturers are not able to pass on the rise in input costs to consumers owing to the emerging competition from Chinese ceramic imports, which further hurt their profitability, the industry body said its study. “This has even lead to closure of certain ceramic units unable to bear rising production costs,” says D.S. Rawat, secretary general of Associated Chambers of Commerce and Industry of India (Assocham). The production of ceramics has been significantly falling short of the prevailing local demand in India and despite making rapid strides for enhancing domestic production capabilities, China continues to be a major supplier of ceramic products to India, the study says. Also, it says the rate of growth for import of Chinese ceramics into India has substantially risen from about eight per cent till a few years ago to over 42 per cent now.

Morgan increases piezoelectric disc production capacity

Morgan Technical Ceramics (MTC) of Stourport-on-Severn, UK, has opened a new production facility for piezoelectric ceramic discs, which can be used in heat-, gas- and water-metering applications. The company says it is responding to growing global demand for ultrasonic domestic utility metering. MTC’s site in Southampton, UK, is now able to produce in excess of ten million piezoelectric ceramic discs a year. Cogeneration is an increasingly popular method of simultaneously generating both electricity and heat. Essentially, excess heat from a central power station is used to heat water, which is then pumped to homes. As a result, heat metering, which measures the flow of water ultrasonically and monitors any drop in temperature, presents a significant opportunity, according to MTC. Meanwhile, ultrasonic products are rapidly replacing mechanical meters in gas- and water usage measurement, as the drive to measure usage more accurately for energy efficiency reasons continues.

New report: Nanotechnology drug delivery market in the US 2012-2016

TechNavio’s analysts forecast the Nanotechnology Drug Delivery market in the US to grow at a CAGR of 84.79 percent over the period 2012-2016. One of the key factors contributing to this market growth is the low R&D cost. The nanotechnology drug delivery market in the US has also been witnessing the trend of emergence of personalized medicines. However, the increasing safety concerns could pose a challenge to the growth of this market. TechNavio’s report, the Nanotechnology Drug Delivery Market in the US 2012-2016, has been prepared based on an in-depth market analysis with inputs from industry experts. It also covers the Nanotechnology Drug Delivery market in the US landscape and its growth prospects in the coming years. The report also includes a discussion of the key vendors operating in this market.

Schott wins BAE Systems’ first Supplier Performance Award for nuclear penetrations

At its First Annual Supplier Forum, BAE Systems Maritime—Submarines has recognized Schott’s Electronic Packaging Business for ten years of outstanding cooperation. The specialist for glass-to-metal sealing technology provides hermetic power, control, and instrumentation penetrations for BAE’s Astute-class submarines. The components safely conduct electricity and data through the containment structure of the submarine’s nuclear reactor. “Since 2003, Schott has consistently been one of our top-performing suppliers,” says Jeannette Medati, BAE Systems Maritime—Submarines Head of Supply Chain Category Management. “The cross-functional, cross-business, and multinational teamwork with Schott serves as a benchmark for what can be achieved by working together with joint aims, open and honest communication, and a will to perform to the highest levels. We hope to continue in a spirit of true partnership for many years to come.” Since the early 1960s, Schott’s glass-to-metal sealed electrical penetration assemblies have been used in naval vessels ranging from civil icebreakers to aircraft and LNG carriers, as well as dozens of active nuclear power plants around the world. In rigorous testing-including seismic simulations and severe accident test programs beyond conditions believed to have occurred in 2011 in Fukushima-the robust components have proven their heat-, pressure-, and radiation-resistant hermeticity and integrity.

Rio Tinto Minerals launches Asia Technology Center to serve growing market

Rio Tinto Minerals has formally launched its Asia Technology Centre (ATC) to serve the growing market for borates in Asia. Rio Tinto Minerals is recognized as a world leader in borate supply and science. Borates are found in a variety of products including high technology glass used in flat screen televisions and laptops, fiberglass to make buildings energy efficient, and fertilizers that help farmers increase crop quality and yield. The ATC in Suzhou, China joins research facilities in the US and is fully developed with laboratories, offices and work spaces, and built for growth. The ATC provides important internal capabilities in glass and ceramics, metals and advanced materials, and agriculture and specialty chemicals to support RTM’s research and development expansion in Asia. The company’s research and development strategy is to partner with customers, universities, government labs and other centers of to pursue commercially relevant innovation.

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U.S. Senator Dianne Feinstein (D-CA) and Erin Donohue at MA’s “Congressional Visits Day” last week. Donohue is a graduate student at the University of California, Santa Barbara in Carlos Levis’s group studying thermal barrier coatings. Credit: ACerS.

Last week the Material Advantage Student Program delegation took their annual trip to Washington, DC, to promote materials science, research, and higher education with elected officials and their staffs. Tricia Freshour, ACerS liaison to the Material Advantage Student Program, was with them and provided this report.

Congressional Visits Day (CVD), organized each year by the Material Advantage Program, was held last week on April 10 and 11 in Washington, DC. The CVD is an annual event that brings students to Washington to raise visibility and support for science, engineering, and technology.

Thirty-seven students and faculty from 13 universities attended this year’s CVD event. CVD is a unique opportunity for materials science and engineering students to advocate for long-term funding for science, engineering and technology through meetings with Congressional decision makers. Security was tight because of sequestration. The students also witnessed thousands of people rallying for immigration on the Capitol lawn, which made getting around DC very busy and hectic, but the weather was great, and the cherry blossoms were in full bloom.

The CVD experience began with an opening reception on Wednesday, April 10, where the students heard three great speakers regarding topics relevant to their visits. Most of the students’ Congressional visits with legislators were scheduled by the students themselves for Thursday, April 11, throughout the day. The students visited with legislative assistants, correspondents, and aides as well as the senators and representatives themselves. One student was even able to snag a photo with a well-known senator on her way to an important vote. [See photo of Senator Dianne Feinstein and student Erin Donohue, above.]

Watch for a full recap of this year’s CVD in the June/July issue of the ACerS’ Bulletin.

The partner societies in the Material Advantage Student Program are The American Ceramic Society, the Association for Iron & Steel Technology, ASM International, and The Minerals, Metals and Materials Society.

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A workshop in July will consider the promise, progress, and funding priorities of solid oxide fuel cell technology. Credit: NETL.

The National Science Foundation uses workshops as a mechanism to bring together the nation’s best minds and research leaders to wrap a scientific community’s collective mind around complex issues. These workshops are not advisory. As I understand it, the NSF is not looking for recommendations on funding, but it does want to facilitate breakthroughs, cross-fertilization of ideas, and encourage new collaborations. NSF program directors usually drop in, too, and provide information on existing funding mechanisms, new programs, etc.

I’m not a researcher, but I’ve been able to sit in on a few NSF workshops. The format usually involves very short presentations by researchers to highlighting a specific aspect of their work. Part of what makes the workshops unique is the extended discussion sessions that follow the presentations. These are very stimulating with lots of questions and clarifications flying back and forth. The best discussions happen when scientists who might not otherwise be aware of each other realize they are attacking similar problems from different angles.

Sound interesting? Another NSF-sponsored workshop is coming up soon: Jason Nicholas, an assistant professor in the chemical engineering and materials science department at Michigan State University, is organizing a workshop on solid oxide fuel cells—”Solid Oxide Fuel Cells: Promise, Progress and Priorities Workshop.” The event will be July 11-12, 2013 in Arlington, Va., and will bring together a mix of people from academia, industry, and government to discuss ways to advance SOFC research and technology.

Why have a workshop now? Solid oxide fuel cell technology has been around for a while, but does not get as much attention—or support—as might be expected. On the website, Nicholas sketches out key achievements—the promise—of SOFC technology.

Despite major accomplishments in the development of SOFCs over the past decade (reducing SOFC operating temperatures from ~800°C to ~600°C, consistently demonstrating power densities in excess of 1W/cm² at 600°C and above, reducing SOFC stack costs from >$1,500/kW to ~$150/kW, etc.), and increasing lifetimes from 15,000 to 40,000 hours, many challenges remain. For instance, improved SOFC materials properties and microstructures will allow low temperature (200-500°C) SOFC operation and the associated benefits of improved thermodynamic efficiencies, longer service lifetimes, rapid start-up times, and cheaper balance-of-plant costs.

Nicholas also captures some of the frustration felt by the SOFC community with the lack of priority, despite technological progress, and channels it productively into a justification for proactively championing SOFC research.

One thing which is clear, however, is that SOFC development in the United States has suffered from federal support that was inconsistent and/or dependent on tangentially related, politically sensitive clean-coal/FutureGen/SECA initiatives. With the scrapping of the DOE SECA program, the unjustified exclusion of SOFCs from President Obama’s “All-of-the-Above” Energy Policy, SOFC leadership slipping to Japan, the political disgrace accompanying the development of other energy conversion/generation/storage technologies (the bankruptcy of battery maker A123, the Dreamliner battery debacle, the failure of solar panel maker Solyndra, etc), the recent increase in domestic natural gas supplies, the continued worldwide use of hydrocarbons, and President Obama’s push to create a Clean Energy Security Trust, now is the perfect time for a Solid Oxide Fuel Cell Promise, Progress, and Priorities (SOFC-PPP) Workshop to re-evaluate the technical promise and funding mechanisms of SOFC research.

The workshop is organized into four sections, each with presentation and discussion format.

1. The Promise of SOFCs
2. Emerging Research Areas
3. Industry Needs
4. Technological, Funding and Political Factors Limiting Domestic and Global SOFC Research and Development

The workshop will include about 37 invited participants and about 13 self-nominated participants. NSF funding will cover a double-occupancy hotel room and airfare of up to $400 for domestic workshop participants. The deadline for applying as a self-nominated workshop participant is May 1, 2013. Please see the website for lodging, travel, registration, and workshop organizational details. The findings and conclusions of the workshop will be published as an open-access, peer-reviewed article in the Winter 2013 issue of Interface.

All interested parties are invited to contribute their ideas and suggestions via an online forum, regardless of whether or not they are participating.

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Strategic Materials Advisory Council cautions DOD against stockpiling Chinese rare earths

The Strategic Materials Advisory Council has cautioned the Department of Defense to avoid the risky mitigation strategy of stockpiling strategic and critical materials from China. The DOD recently completed its biannual “Strategic and Critical Materials 2013 Report on Stockpile Requirements,” which recommended stockpiling $120.43 million of heavy rare earth elements—materials produced only in China. ”The root cause of these material shortages is our ongoing dependence on Chinese suppliers,” says Council Executive Director Jeff Green. “While it is encouraging that DoD acknowledges these risks, we urge DOD to move from theoretical studies to the only appropriate and permanent solution: the creation and nurturing of a US-based rare earth supply chain.” The rare earth stockpile recommendation represents over one-third of a $319.74 million stockpiling plan to mitigate a $1.2 billion shortfall of 23 strategic and critical materials. This encouraging recommendation contrasts dramatically with previous DOD assessments that asserted domestic sources could meet all military requirements by 2013, except for yttrium, and that substitution would be a viable approach to risk mitigation for heavy rare earths.

‘Smart’ chemo drug goes easy on fertility

A new chemotherapy drug in the form of nanoparticles is less toxic to young women’s fertility but extra tough on cancer, say researchers. “Our overall goal is to create smart drugs that kill the cancer but don’t cause sterility in young women,” says Teresa Woodruff, a co-principal investigator of the study and chief of fertility preservation at Northwestern University. The chemotherapy drug, arsenic trioxide, is packed into a very tiny Trojan horse called a nanobin. The nanobin consists of nano-size crystalline arsenic particles densely packed and encapsulated in a fat bubble. The fat bubble, a liposome, disguises the deadly cargo-half a million drug molecules. The fat bubble is the perfect size to stealthily slip through holes in the leaky blood vessels that rapidly grow to feed tumors. The local environment of the tumor is often slightly acid and it’s this acid that causes the nanobin to release its drug cargo and deliver a highly effective dose of arsenic where it is needed. The scientists show this approach to packaging and delivering the active drug has the desired effect on the tumor cells but prevents damage to ovarian tissue, follicles, or eggs. Arsenic trioxide was approved a few years ago for treating some types of blood cancers such as leukemia in humans, but the researchers think the arsenic trioxide nanobins can be used against breast cancer and other solid tumors.

Harvesting unused energy with flat, printed thermoelectrics

At the Hannover trade fair, Fraunhofer researchers are now presenting a new manufacturing process with which these thermoelectric generators can be cost-effectively produced in the form of large-area flexible components from non-toxic synthetic materials. The scientists‘ vision is described by Aljoscha Roch of the Fraunhofer Institute for Material and Beam Technology IWS in Dresden: “Thermoelectric generators (TEG) currently have an efficiency of around eight percent. That sounds very small. But if we succeed in producing TEG cost-effectively, on a large scale and from flexible materials we can install them extensively on the insides of the concave cooling tower wall. In this way, through the enormous amount of energy produced in the huge plants—around 1500 liters of water evaporate per minute—we could generate large quantities of electricity.” The scientists have succeeded in producing TEGs by means of a printing process. The miniaturized generators can not only be produced cost-effectively, on large surfaces and in a flexibly manageable manner, but an additional major advantage is that the materials used are environmentally-friendly. “TEG are today largely produced by hand from toxic components which contain lead for example. We are now using modern 3D printing technology and harmless polymers (plastics) that are electrically conductive,” explains Roch. The IWS researchers are demonstrating the printed TEG for the first time in a cooling tower model at the Hannover trade fair.

To trap a rainbow, slow down light

Researchers have developed a “hyperbolic metamaterial waveguide” that halts and ultimately absorbs each frequency of light, at slightly different places in a vertical direction, to catch a “rainbow” of wavelengths. The technology is essentially an advanced microchip made of ultrathin films of metal and semiconductors and/or insulators. ”Right now, researchers are developing compact light absorbers based on optically thick semiconductors or carbon nanotubes. However, it is still challenging to realize the perfect absorber in ultrathin films with tunable absorption band,” says Qiaoqiang Gan, an assistant professor of electrical engineering at University at Buffalo. Gan previously helped pioneer a way to slow light without cryogenic gases. He and other researchers at Lehigh University made nanoscale-sized grooves in metallic surfaces at different depths, a process that altered the optical properties of the metal. While the grooves worked, they had limitations. For example, the energy of the incident light cannot be transferred onto the metal surface efficiently, which hampered its use for practical applications. As reported in the journal Scientific Reports, the waveguide solves that problem because it is a large area of patterned film that can collect the incident light efficiently. Researchers say the technology could lead to advancements in an array of fields, such as preventing crosstalk in electronics or energy-harvesting devices.

Carnegie Institution releases ‘Advances in Matter Under Extreme Conditions’ report on 2012 HPCAT Workshop

The High-Pressure Collaborative Access Team (HPCAT), a group linked to the Advanced Photon Source (APS) facility at the Argonne National Lab, held a workshop Oct. 10-12, 2012, to review the successes of HPCAT over the past 10 years, as well as opportunities for addressing key grand challenges in future of extreme conditions science. During the past decade, HPCAT has taken advantage of the nation’s most brilliant high-energy synchrotron source and developed a multitude of integrated synchrotron radiation techniques optimized for high-pressure research. These X-ray probes, integrated with hydrostatic or uniaxial compression, static or dynamic loading, resistive or laser heating, and cryogenic cooling, have enabled users’ investigations of structural, vibrational, electronic, and magnetic properties at high pressure and high/low temperature that were not possible a decade ago. The workshop consisted of over 120 people from the US and abroad. Emerging from the workshop and its discussions is a clear signal of the outstanding opportunities for the future of extreme conditions science at the APS in the years to come. The report is approximately 120 pages (pdf)

Superconductivity: denser, better

New experiments set the record of the superconducting transition temperatures for a new family of iron-based selenide superconductors. These materials were recently found to superconduct below 30 K, but their transition temperatures decline until approaching absolute zero temperature with the application of pressure. Now Carnegie scientists Xiao-Jia Chen, Lin Wang, and Ho-Kwang Mao, in collaboration with scientists from from the National Institute of Standards and Technology, the Chinese Academy of Science, and Zhejiang University, have uncovered reemerging superconductivity above 48 K in iron selenides upon further compression. The disappearance of superconductivity in the low-pressure cycle and the re-emergence of superconductivity with higher transition temperatures in the high-pressure cycle reflect detailed structural variances within the basic unit cell itself. The two superconducting domes were likely the result of different charge carriers. Finding the reentrance of superconductivity at 48 K in the new iron family of superconductors points to the possibility of achieving similar higher transition temperatures at ambient pressure through some structural modifications

Researchers find that tiny nanowires can lift liquids as effectively as tubes

New research carried out at MIT and elsewhere has demonstrated for the first time that when inserted into a pool of liquid, nanowires - wires that are only hundreds of nanometers across - naturally draw the liquid upward in a thin film that coats the surface of the wire. The finding could have applications in microfluidic devices, biomedical research and inkjet printers. Although this upward pull is always present with wires at this tiny scale, the effect can be further enhanced in various ways: Adding an electric voltage on the wire increases the force, as does a slight change in the profile of the wire so that it tapers toward one end. The researchers used nanowires made of different materials—silicon, zinc oxide and tin oxide, as well as two-dimensional graphene—to demonstrate that this process applies to many different materials. The results are published in the journal Nature Nanotechnology by a team of researchers led by Ju Li, an MIT professor of nuclear science and engineering and materials science and engineering, along with researchers at Sandia National Laboratories in New Mexico, the University of Pennsylvania, the University of Pittsburgh, and Zhejiang University in China. Several brief videos of the nanowires in action have been posted on YouTube by Li’s research group.

Even graphene has weak spots

Even graphene, the Superman of materials, has its kryptonite: Defects in polycrystalline graphene will sap its strength. The unexpected weakness is in the form of a seven-atom ring that inevitably occurs at the junctions of grain boundaries in graphene, where the regular array of hexagonal units is interrupted, report researchers. At these points, under tension, polycrystalline graphene has about half the strength of pristine samples of the material. New research shows defects in polycrystalline forms of graphene will sap its strength. The new calculations could be important to materials scientists using graphene in applications where its intrinsic strength is a key feature, like composite materials and stretchable or flexible electronics. The team calculated that the particular seven-atom rings found at junctions of three islands are the weakest points, where cracks are most likely to form. These are the end points of grain boundaries between the islands and are ongoing trouble spots.

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