First introduced in 19th-century Europe, bicycles evolved quickly into their familiar, current design.
Numbering over 1,000,000,000 in the world today, bicycles provide the principal means of transportation in many regions and a popular form of recreational transport in others.
Based on micro fuel cell technology developed at KTH Royal Institute of Technology in Stockholm, the MyFC PowerTrekk uses ordinary water to extend battery life for devices of up to 3 watts.
Anders Lundblad, KTH researcher and founder of MyFC, says that the device can be powered by fresh or seawater. The water need not be completely clean.
"Our invention has great potential to accelerate social development in emerging markets," Lundblad says. "There are large areas that lack electricity, while mobile phones fulfil more and more vital functions, such as access to weather information or electronic payment."
A USB connector attaches the compact PowerTrekk charger to the device. When plain water is poured onto a small disposable metal disc inside the unit, hydrogen gas is released and combines with oxygen to convert chemical energy into electrical energy. The resulting charge is enough to power an iPhone to between 25 and 100 per cent of its battery capacity.
Lundblad has done research on micro fuel cells and small flat Proton Exchange Membrane (PEM) fuel cells for more than 15 years at the Department of Applied Electrochemistry at KTH. He says the business vision behind MyFC is to commercialise fuel cell technology and contribute to the development of environmental technology.
He says the charger is the first step toward building fuel cells in laptops.
"The launch of our charger is a strategic move to gain wide acceptance of fuel cells throughout society," he says. "Our chargers may be considered expensive now; but in the longer term, as they reach a mass market, they would go down in price."
Fuel cells can already be found in electric cars, trucks and buses, and backup electrical power supply systems for hospitals and cogeneration plants. The process by which fuel cells generate electricity is considered to be safe and environmentally-friendly, and the only by-product is water vapour. The fuel cell system is passive and has no fans or pumps.
Lundblad says that fuel cell chargers are faster and more reliable than solar chargers. The main target groups for MyFC PowerTrekk are those who travel or live in remote areas of the world, outdoor enthusiasts and aid workers, he says.
The charger is both a fuel cell and a portable battery, providing a direct power source as well as a storage buffer for the fuel.
MyFC plans to open an online shop for its MyFC PowerTrekk product. The company has already sold the technology to users in China, Japan, the U.S. and much of Europe.
A "hybrid" anode developed at the Department of Energy's Pacific Northwest National Laboratory could quadruple the life of lithium-sulfur batteries. Nature Communications published a paper today describing the anode's design and performance.
"Lithium-sulfur batteries could one day help us take electric cars on longer drives and store renewable wind energy more cheaply, but some technical challenges have to be overcome first," said PNNL Laboratory Fellow Jun Liu, who is the paper's corresponding author. "PNNL's new anode design is helping bringing us closer to that day."
Today's electric vehicles are commonly powered by rechargeable lithium-ion batteries, which are also being used to store renewable energy. But the chemistry of lithium-ion batteries limits how much energy they can store. One promising solution is the lithium-sulfur battery, which can hold as much as four times more energy per mass than lithium-ion batteries. This would enable electric vehicles to drive longer on a single charge and help store more renewable energy. The down side of lithium-sulfur batteries, however, is they have a much shorter lifespan because they can't be charged as many times as lithium-ion batteries.
Most batteries have two electrodes: one is positively charged and called a cathode, while the second is negative and called an anode. Electricity is generated when electrons flow through a wire that connects the two. Meanwhile, charged molecules called ions shuffle from one electrode to the other through another path: the electrolyte solution in which the electrodes sit.
The lithium-sulfur battery's main obstacles are unwanted side reactions that cut the battery's life short. The undesirable action starts on the battery's sulfur-containing cathode, which slowly disintegrates and forms molecules called polysulfides that dissolve into the battery's electrolyte liquid. The dissolved sulfur eventually develops into a thin film called the solid-state electrolyte interface layer. The film forms on the surface of the lithium-containing anode, growing until the battery is inoperable.
Most lithium-sulfur battery research to date has centered on stopping sulfur leakage from the cathode. But PNNL researchers determined stopping that leakage can be particularly challenging. Besides, recent research has shown a battery with a dissolved cathode can still work. So the PNNL team focused on the battery's other side by adding a protective shield to the anode.
The new shield is made of graphite, a thin matrix of connected carbon molecules that is already used in lithium-ion battery anodes. In a lithium-sulfur battery, PNNL's graphite shield moves the sulfur side reactions away from the anode's lithium surface, preventing it from growing the debilitating interference layer. Combining graphite from lithium-ion batteries with lithium from conventional lithium-sulfur batteries, the researchers dubbed their new anode a hybrid of the two.
The new anode quadrupled the lifespan of the lithium-sulfur battery system the PNNL team tested. When equipped with a conventional anode, the battery stopped working after about 100 charge-and-discharge cycles. But the system worked well past 400 cycles when it used PNNL's hybrid anode and was tested under the same conditions.
"Sulfur is still dissolved in a lithium-sulfur battery that uses our hybrid anode, but that doesn't really matter," Liu said. "Tests showed a battery with a hybrid anode can successfully be charged repeatedly at a high rate for more 400 cycles, and with just an 11-percent decrease in the battery's energy storage capacity."
This and most other lithium-sulfur battery research is conducted with small, thin-film versions of the battery that are ideal for lab tests. Larger, thicker batteries would be needed to power electric cars and store renewable energy. Liu noted tests with a larger battery system would better evaluate the performance of PNNL's new hybrid anode for real-world applications.
This study was primarily supported by the Department of Energy's Office of Science (BES), with additional support from DOE's Advanced Research Projects Agency-Energy, and DOE's Office of Energy Efficiency and Renewable Energy. Some of this research was performed at EMSL, DOE's Environmental and Molecular Sciences Laboratory at PNNL.
A contentious controversy surrounds the high intensity of one leading LED semiconductor -- indium gallium nitride (InGaN) -- with experts split on whether or not indium-rich clusters within the material provide the LED's remarkable efficiency. Now, researchers from the Massachusetts Institute of Technology (MIT) and the U.S. Department of Energy's (DOE) Brookhaven National Laboratory have demonstrated definitively that clustering is not the source. The results -- published online May 16 in Applied Physics Letters -- advance fundamental understanding of LED technology and open new research pathways.
"This discovery helps solve a significant mystery in the field of LED research and demonstrates breakthrough experimental techniques that can advance other sensitive and cutting-edge electronics," said Silvija Gradečak, the Thomas Lord Associate Professor of Materials Science and Engineering at MIT and a coauthor on the study. "The work brings us closer to truly mastering solid-state technologies that could supply light and energy with unprecedented efficiency."
Building a Better Bulb
Incandescent lights -- the classic bulbs that use glowing wires of tungsten or other metals -- convert only about five percent of their energy into visible light, with the rest lost as heat. Fluorescent lights push that efficiency up to about 20 percent, still wasting 80 percent of the electricity needed to keep homes and businesses bright. In both of these instances, light is only the byproduct of heat-generating reactions rather than the principal effect, making the technology inherently inefficient.
"Solid-state lights convert electric current directly into photons," said Eric Stach, leader of the Electron Microscopy Group at Brookhaven Lab's Center for Functional Nanomaterials (CFN) and a co-author on the study. "LED bulbs use semiconductors to generate light in a process called electroluminescence. The efficiency of this process could, in theory, be nearly perfect, but the experimental realization has not reached those levels. That disconnect helped motivate this study."
For this study, the scientists looked at the LED compound InGaN (pronounced in-gan), which is particularly promising for practical applications. InGaN alloys contain dislocations -- structural imperfections that could inhibit electricity flow and light production -- but somehow the alloy performs exceptionally well. To understand the light-emitting reactions, physicists needed to understand what was happening on the atomic scale. After researchers started to investigate, however, not everyone reached the same conclusions.
Controversial Clusters
"Years ago, a team of researchers used electron microscopes to examine InGaN samples, and they identified a surprising phenomenon -- the material appeared to be spontaneously decomposing and forming these isolated indium-rich clusters," Stach said. "This behavior could explain the efficient light emission, as the clusters might help electrons avoid the structural problems in the InGaN. But then things became really interesting when another group proposed that the electron microscope itself caused that clustering decomposition. We had a real divide in the semiconductor field."
Rather than using light to examine materials, electron microscopes bombard samples with finely tuned beams of electrons and detect their interactions when they pass through a sample to reveal atomic structures. To achieve high enough resolution to examine the InGaN alloys, the electron microscopes used in the older experiments needed high-voltage beams. The controversy revolved around whether or not the experiment itself produced the clusters, rather than discovering the mechanism behind efficient light emission.
Improved Imaging
"The state-of-the-art instruments available at Brookhaven Lab's CFN changed the way we could test these promising materials," Gradečak said. "The CFN's aberration-corrected scanning transmission electron microscope (STEM) opened a new and non-destructive window into the LED samples. For the first time, we could get Ångstrom-level details -- that's one tenth of one nanometer -- without the risk of the device affecting the sample."
The researchers combined the leading STEM techniques with high-resolution electron energy loss spectroscopy (EELS), which measured the energy lost by electrons as they passed through the sample. Post-doctoral researchers Kamal Baloch of MIT -- the lead author of the study -- and Aaron Johnston-Peck of CFN actually applied these imaging techniques to the same samples that first launched the controversy over clustering, helping further settle the issue.
"We found that the indium-rich clusters do not actually exist in these samples, even though they remain efficient light emitters," Baloch said. "While clustering may still occur in other samples, which may be prepared in different ways, the important point is that we've established a foolproof method for investigating InGaN materials. We can use these non-destructive imaging techniques to explore the fundamental relationship between cluster formation and light emission to help unlock the secrets of this amazing alloy."
Beyond the advanced imaging instruments, researchers used the expertise of Brookhaven Lab physicist Kim Kisslinger, who specializes in nanoscale sample preparation. The InGaN samples were reduced to a thickness of just 20 nanometers, an essential step in priming the materials for STEM and EELS experimentation. The samples were also painstakingly cleaned and polished to eliminate artifacts that might impact image resolution.
The research was supported by the Center for Excitonics, an Energy Frontier Research Center funded by the U.S. Department of Energy's Office of Science. The work at Brookhaven Lab's Center for Functional Nanomaterials was also supported by DOE's Office of Science, with additional work carried out at the MIT Center for Materials Science Engineering.
Terahertz waves (THz) are found on the furthest extreme of the infrared band, just before the beginning of the microwave band. "This area is possibly the last range of the electromagnetic spectrum that is yet to be developed and exploited," comment the scientists. Although in recent years research has produced significant advances in the systems used to generate and detect this submillimetric radiation, it is still necessary to develop technologies with enough quality, flexibility and ease of use to cause an explosion in the commercialization of the THz range, points out Ángel Rubén Criado, one of the founding partners of Luz WaveLabs.
This company, a spin off hatched in UC3M's Department of Electronic Technology with the support of theVivero de Empresas (Business Incubator) in UC3M's Parque Científico (Science Park), is attempting to design high performance tools that can introduce THz waves to new sectors and convert this technology into an everyday tool within the next few years. Their star product is the "pure-T-wave," a THz generator that combines the advantages of electronics and photonics to obtain a "signal quality that is one million times greater than the one produced by the best photonic THz generator that is currently on the market," states the researcher.
Evolution of Nobel Prize winning technology
In order to do this, the researchers have used an "optic seed" (Optical Frequency Comb; OFC) of very high precision and coherence. This source of laser spectroscopy is similar to the one developed by John L. Hall and Theodor W. Hänsch (who won, thanks to this development, the Nobel Prize for Physics in 2005), although in this case the Spanish researchers have introduced a series of modifications that have allowed them to significantly reduce the device's cost, size and consumption. In fact, they recently published an article in Photonics Technology Letters about the most energy efficient OFC in the world.
Building from this OFC source, the researchers combine radiofrequency and photonic electronic techniques to synthesize a very high quality THz signal. "The quality of the signal is so high that it has not been possible to measure some of the parameters with precision; they are higher than the measurement limits of our laboratory instruments," explains the researcher, who is currently working on the development of the commercial system. "Industrializing the laboratory prototype will be an important challenge; our objective is to provide a totally automated system that is easy for users with no specific training in this technology to operate," he notes.
Promising applications
The projected date for the market launch of this generator is the second trimester of 2015. The objective set by Luz WaveLabs is to create a device that is easy to use, allowing any type of user to employ this technology. The commercial systems that are currently available are much more oriented to scientists, who use them in their research; however, this innovation will be available for use by architects, doctors, and technicians controlling industrial processes, for example.
The characteristics of this type of radiation make this technology a very promising field of development for the coming years, according to the researchers. Because THz waves are harmless (non ionizing), they open the way for new, massive security systems in airports or stadiums. Their spectroscopic properties can be used in the detection of cancer and other diseases, as well as in the inspection from a distance, without causing damage, of metal and wooden structures (historical building), and hazardous materials in packages (transportation of merchandise), or the detection of invisible fractures or defects (factories). From a scientific perspective, the application that has given the greatest impulse to the development of THz waves is radio astronomy. "Since most black-body radiation and a large quantity of molecular and intermolecular resonances are located in the area of the THz waves, having powerful, high quality tools to work in this field will lead, in the future, to great advances in our understanding of the origin and function of the universe," he concludes.
In their search for innovative methods to restore heart function, scientists have been exploring cardiac "patches" that could be transplanted into the body to replace damaged heart tissue. Now, in his Tissue Engineering and Regenerative Medicine Laboratory, Dr. Tal Dvir and his PhD student Michal Shevach of Tel Aviv University's Department of Molecular Microbiology and Biotechnology and the Center for Nanoscience and Nanotechnology, together with their colleagues, are literally setting a gold standard in cardiac tissue engineering.
To meet one of the biggest challenges in the development of cardiac patches -- ensuring that engineered tissue can mimic the heart's coordinated electrical system, which controls heartbeat and rhythm -- they integrated cardiac cells with nanofibers made of gold particles to form functional engineered tissues. Their goal is to optimize electrical signalling between cells.
Gold has been found to increase the connectivity of biomaterials, explains Dr. Dvir. With the addition of the gold particles, cardiac tissues contract much faster and stronger as a whole, he reports, making them more viable for transplants. The research was recently published in the Journal of Materials Chemistry B.
Lending nature a helping hand
On their surface, heart cells contain proteins that are responsible for transferring electrical signals. But the process of tissue engineering itself leads to the loss of these proteins. And while the cells will start to produce them again naturally, says Dr. Dvir, they take time to develop -- time which a patient may not have. Gold nanofibers can fill the role of electrical connectors until the cells are able to produce their own connectors once more.
New tissues are created by placing cells taken from patients or animals onto a three-dimensional scaffolding made of biomaterials -- any matter or surface that interacts with biological systems -- which organize the cells into the proper formation as they grow. Dr. Dvir and his team used various chemical and physical processes to integrate gold nanoparticles into their scaffolds. The cells then interacted with each other through these gold nanoparticles.
The researchers used a scanning electron microscope and various measures of electrical activity in order to observe the nanoparticles on the fibers and check conductivity. Cells placed on the gold-embedded scaffolding had significantly stronger contractions compared to those on a scaffolding without gold. Importantly, the cells contracted in unison, demonstrating effective electrical signalling between them.
A golden opportunity
Because 50 percent of heart attack victims die within five years of their initial attack, new treatment options are sorely needed. A functioning, transplantable tissue could not only save lives, but improve a patient's quality of life overall.
Having demonstrated the electrical signalling capability of these gold infused cardiac patches, Dr. Dvir will next evaluate their potential to improve function after heart attack through pre-clinical tests in the lab and, eventually, clinical trials with patients. He says that the ideal method would be to use a patient's own cells when building the new tissue, therefore avoiding the risk of rejection.
In their search for innovative methods to restore heart function, scientists have been exploring cardiac "patches" that could be transplanted into the body to replace damaged heart tissue. Now, in his Tissue Engineering and Regenerative Medicine Laboratory, Dr. Tal Dvir and his PhD student Michal Shevach of Tel Aviv University's Department of Molecular Microbiology and Biotechnology and the Center for Nanoscience and Nanotechnology, together with their colleagues, are literally setting a gold standard in cardiac tissue engineering.
To meet one of the biggest challenges in the development of cardiac patches -- ensuring that engineered tissue can mimic the heart's coordinated electrical system, which controls heartbeat and rhythm -- they integrated cardiac cells with nanofibers made of gold particles to form functional engineered tissues. Their goal is to optimize electrical signalling between cells.
Gold has been found to increase the connectivity of biomaterials, explains Dr. Dvir. With the addition of the gold particles, cardiac tissues contract much faster and stronger as a whole, he reports, making them more viable for transplants. The research was recently published in the Journal of Materials Chemistry B.
Lending nature a helping hand
On their surface, heart cells contain proteins that are responsible for transferring electrical signals. But the process of tissue engineering itself leads to the loss of these proteins. And while the cells will start to produce them again naturally, says Dr. Dvir, they take time to develop -- time which a patient may not have. Gold nanofibers can fill the role of electrical connectors until the cells are able to produce their own connectors once more.
New tissues are created by placing cells taken from patients or animals onto a three-dimensional scaffolding made of biomaterials -- any matter or surface that interacts with biological systems -- which organize the cells into the proper formation as they grow. Dr. Dvir and his team used various chemical and physical processes to integrate gold nanoparticles into their scaffolds. The cells then interacted with each other through these gold nanoparticles.
The researchers used a scanning electron microscope and various measures of electrical activity in order to observe the nanoparticles on the fibers and check conductivity. Cells placed on the gold-embedded scaffolding had significantly stronger contractions compared to those on a scaffolding without gold. Importantly, the cells contracted in unison, demonstrating effective electrical signalling between them.
A golden opportunity
Because 50 percent of heart attack victims die within five years of their initial attack, new treatment options are sorely needed. A functioning, transplantable tissue could not only save lives, but improve a patient's quality of life overall.
Having demonstrated the electrical signalling capability of these gold infused cardiac patches, Dr. Dvir will next evaluate their potential to improve function after heart attack through pre-clinical tests in the lab and, eventually, clinical trials with patients. He says that the ideal method would be to use a patient's own cells when building the new tissue, therefore avoiding the risk of rejection.
