Smart windows can be tuned for privacy, while still letting the light shine through

 

Imagine if you could turn up the opacity for a bit of privacy, just as you would with regular blinds, without compromising on brightness? (Credit: Timothy Zarki/University of Cincinnati) Image Gallery (9 images) The glass panels that let light into our homes and offices have been seen as huge windows of opportunity for engineers in recent times. If the amount of light pouring through can be managed throughout the day, it could lessen reliance on energy-sapping air conditioner units, for instance. This has led to a number of examples of smart facades that keep interior spaces from overheating, and some that even harvest energy for lights and ventilation. But a new tunable window-tinting technology is claimed to do things the smart glass before it cannot, by allowing users control over brightness, color temperature and opacity. Scientists from the University of Cincinnati (UC) teamed up with researchers from Hewlett Packard, Merck and National Taiwan University in developing the tunable windows. The team set out to produce an adaptation of the technology found in e-paper electronic displays that could scale to cover entire window panes without being prohibitively expensive. Around three years in the making, the final, patent-pending design is claimed to be simple and cheap to manufacture. Two glass substrates enclose a layer of polymer, a set of electrodes, and micro-replicated polymer nubs. This results in a honeycomb-pattern coating that can be integrated into new windows or even rolled onto existing ones. "Basically, one color has one charge," explains UC's Sayantika Mukherjee, who led the research. Another color has another charge, and we apply voltage to repel or attract the colors into different positions. The basic technology is not that different from what our group has previously demonstrated before in electronic display devices." So, imagine if you could turn up the opacity for a bit of privacy, just as you would with regular blinds, without compromising on brightness? Or adjust the windows to bring feelings of warmth to your cold, bare basement, like you could with one of Phillips' Hue lightbulbs? The researchers say the tunable windows can make this possible. They report that when the windows are turned milky for privacy, they are capable of still letting through 90 percent of natural light. Furthermore, the team says the system can allow for other types of configurations. This might involve controlling both visible light and infrared heat transmission at the same time. Such a function could find use in summer months to prevent the house heating up, or in the winter months to help keep it warm and toasty. The researchers are hopeful that the solution will lead to inexpensive window tinting that replaces conventional shades and blinds. The research was published in the journal Applied Optics.   Source: University of Cincinnati

New algorithm paves the way for light-based computers

 

Optical interconnects made of silicon act as a prism to direct infrared light transferring data between computer chips An inverse design algorithm developed by Stanford engineers enables the design of silicon interconnects capable of transmitting data between computer chips via light. The new process replaces the wire circuitry used to relay information electronically, which could lead to the development of highly efficient, light-based computers. While the heavy lifting in computer processing takes place inside the chips, an analysis by Stanford professor of electrical engineering, David Miller, showed that up to 80 percent of a microprocessor’s power is eaten up by the transmitting of data as a stream of electrons over wire interconnects. Basically, shipping requires far more energy than production, and chewing through all that power is the reason laptops heat up. Inspired by the optical technology of the internet, the researchers sought to move data between chips over fiber optic threads beaming photons of light. Besides using far less energy than traditional wire interconnects, chip-scale optic interconnects can carry more than 20 times more data. The majority of fiber optics are made from silicon, which is transparent to infrared light the same way glass is to visible light. Thus, using optical interconnects made from silicon was an obvious choice. “Silicon works,” said Tom Abate, Stanford Engineering communications director. “The whole industry knows how to work with silicon.” But optical interconnects need to be designed one at a time, making the switch to the technology impractical for computers since such a system requires thousands of such links. That’s where the inverse design algorithm comes in. The software provides the engineers with details on how the silicon structures need to be designed for performing tasks specific to their optical circuitry. The group designed a working optical circuit in the lab, copies were made, and all worked flawlessly despite being constructed on less than ideal equipment. The researchers cite this as proof of the commercial viability of their optical circuitry, since typical commercial fabrication plants use highly precise, state-of-the-art manufacturing equipment. While details of the algorithm’s functions is a tad complex, it basically works by designing silicon structures that are able to bend infrared light in various and useful ways, much like a prism bends visible light into a rainbow. When light is beamed at the silicon link, two wavelengths, or colors, of light split off at right angles in a T shape. Each silicon thread is miniscule – 20 could sit side-by-side within a human hair. The optical interconnects can be constructed to direct specific frequencies of infrared light to specific locations. And it’s the algorithm that instructs how to create these silicon prisms with just the right amount and bend of infrared light. Once the calculation is made as to the proper shape for each specific task, a tiny barcode pattern is etched onto a slice of silicon. Building an actual computer that uses the optical interconnects has yet to be realized, but the algorithm is a first big step. Other potential uses for the algorithm include designing compact microscopy systems, ultra-secure quantum communications, and high bandwidth optical communications. The team describes their work in the journal Nature Photonics. Source: Stanford University

Tools for real-time visual collaboration

 

National Science Foundation (NSF) Discoveries Indiana and Purdue University professors design cyberlearning system to make sharing ideas easier Concept sketches of a toy helicopter in skWiki, which supports multiple histories for an object. Credit and Larger Version June 10, 2015 Increasingly, professionals in all sorts of fields need to work together to rapidly design new and complex solutions to pressing problems. Often, these teams are geographically or temporally distributed. "We've had great tools in the past to collaborate on texts, but we haven't had great tools for us to collaborate visually," said Kylie Peppler, an assistant professor of learning sciences at Indiana University. "As a result, much of today's innovative design work still occurs through pen-and-paper sketching, which is challenging to share and systematically build upon." On Thursday, June 11, Peppler takes part in the Capitol Hill Maker Faire, which immediately precedes the June 12-18 Week of Making announced by the White House. Peppler will be on a panel at 2:00 p.m. titled "Making in Community." In an earlier presentation at the National Science Foundation (NSF), Peppler and Karthik Ramani, a professor of mechanical engineering at Purdue University, described two new interactive collaboration tools they've designed--skWiki (or Sketch Wiki, pronounced 'squeaky') and Juxtapoze--that significantly improve creative collaboration in the visual design process. For the last 18 years, Ramani has taught a class on toy design at Purdue. The university purchased its first 3-D printers in 1995 and has consistently been on the technological cutting edge. But digital collaboration among students had remained a challenge. "Computers have been individualistic devices," said Ramani. "But a new class of technology is emerging that allows us to engage in our individual learning process and also in a collaborative process." SkWiki is an example of such technology. It allows many participants to collaboratively create digital multimedia projects on the web using many kinds of media types, including text, hand-drawn sketches and photographs. Whereas collaborative writing tools like Wikipedia and Google Docs don't allow for divergent thinking, SkWiki does, the researchers say. Individuals can contribute elements to others' designs or clone components from your peers' work and integrate them into your own. Ramani and Peppler released the tool to the public in March 2014, and presented the project at the 2014 Association for Computing Machinery (ACM) conference on Human Factors in Computing Systems last June. A second tool they developed, Juxtapoze, lets students draw shapes that the program matches to existing web images, leading to serendipitous discoveries and open-ended creativity. "Juxtapoze lowers the barriers to entry for people to make creative things in a very fluid manner," said Peppler. A plug in for skWiki--the first of many, according to the researchers--Juxtapoze quickly matches scribbles generated by the designer with images found on the Internet, leading to serendipitous connections: for instance, a circle may become a wheel, or a squiggly line, a snake. With Juxtapoze, "technology starts to be a partner in the design process and gets students to think in more divergent ways," she said. Ramani and Peppler believe the two technologies have the potential to transform the design process into a more collaborative, creative and efficient endeavor. "We've created a platform that can change things in a strategic way to maximize learning," said Ramani. "This new class of tools allows us to have better fluidity between our ideas and our design and lets students accomplish complicated engineering concepts in a short time scale." Beyond enabling collaboration, SkWiki and Juxtapoze have the capacity to generate useful data about the creative design process itself, a potentially rich source for research into the impact of technology and collaboration on learning processes. "Process is more important than final product, but it's often not treated that way," Peppler said. "These tools capture and privilege the process."   Aaron Dubrow, NSF (703) 292-4489 adubrow@nsf.gov Investigators Kylie Peppler Karthik Ramani Related Institutions/Organizations Purdue University Indiana University Related Programs Cyber-Human Systems Cyberlearning and Future Learning Technologies Related Awards #1249229 EAGER: skWiki - A Sketch-based Wiki #0535156 3D Sketch-Based System for Conceptual Design #1227639 DIP: V-ICED Visually-Integrated Cyber Exploratorium for Design #1312167 AIR Option 1: Technology Translation Gesture-based free form shape modeling Years Research Conducted 2009 - 2014 Total Grants $1,479,490

Study shows how the US could achieve 100 percent renewable energy by 2050

 

A study points the way to a renewable energy reliant United States in just 35 years (Credit: Shutterstock) A team of researchers led by Stanford University's professor Mark Z. Jacobson has produced an ambitious roadmap for converting the energy infrastructure of the US to run entirely on renewable energy in just 35 years. The study focuses on the wide-scale implementation of existing technologies such as wind, solar and geothermal solutions, claiming that the transition is both economically and technically possible within the given timeframe. As a starting point, the researchers looked at current energy demands on a state-by-state basis, before calculating how those demands are likely to evolve over the next three and a half decades. Splitting the energy use into residential, commercial, industrial and transportation categories, the team then calculated fuel demands if current generation methods – oil, gas, coal, nuclear and renewables – were replaced with electricity. That already sounds like a mammoth task, but its true complexity comes to light when you consider that for the purposes of the study, absolutely everything has to run on electricity. That means everything from homes and factories to every vehicle on the road. As it turns out, while the calculations might be complex, the results are extremely promising. "When we did this across all 50 states, we saw a 39 percent reduction in total end-use power demand by the year 2050," said Jacobson. "About 6 percentage points of that is gained through efficiency improvements to infrastructure, but the bulk is the result of replacing current sources and uses of combustion energy with electricity." In order for each state to make the transition, it would focus on the use of the most easily available renewable sources. For example, some states get a lot more sunlight than others, some have a greater number of south-facing rooftops, while coastal states can make use of offshore wind farms, and for others geothermal energy is a good option. Interestingly, the plan doesn't involve the construction of new hydroelectric dams, but does call for improved efficiency of existing facilities. It would also only require a maximum of 0.5 percent of any one state's land to be covered in wind turbines or solar panels. The team looked at all of the above before laying out a roadmap for each state to become 80 percent reliant on clean, renewable energy by 2030, with a full transition achieved by 2050. Some states are more prepared to make the change than others. For example, Washington state already draws some 70 percent of its current electricity from hydroelectric sources, and both Iowa and South Dakota use wind power for around 30 percent of their electricity needs. So what would all of this cost? Well, according to the research, the initial bill would be fairly hefty, but thanks to the sunlight and wind being free, things would level out in the long run, roughly equaling the cost of the current infrastructure. "When you account for the health and climate costs – as well as the rising price of fossil fuels – wind, water and solar are half the cost of conventional systems," said Jacobson. "A conversion of this scale would also create jobs, stabilize fuel prices, reduce pollution-related health problems and eliminate emissions from the United States. There is very little downside to a conversion, at least based on this science." Not only would it be economically viable to make the switch, but it would also have some significant knock-on health benefits, as approximately 63,000 people currently die from air pollution-related cases in the US every year. The researchers published the results of their study in the journal Energy and Environmental Sciences. There's also an interactive map available, detailing how each state would make use of available renewables. Source: Stanford University

The Ultimate Guide To Solar Panels

 

GreenMatch.co.uk The Ultimate Guide To Solar Panels Clouds are not a problem Contrary to common thought, solar panels work in cloudy weather too. Although it is true that the output will be maximized when the amount of sunlight hitting the panels is greater, solar panels have proved to be significantly efficient in grey weather such as that of the UK. Efficiency Efficiency is one of the most looked-at features. A solar panel in simple terms consists of a group of solar cells that are grouped next to each other on top of a backsheet and covered by glass. Solar cell efficiency refers to the amount of light that a single cell can convert into electricity and solar panel efficiency is the amount of light that one entire module can convert into electricity. Solar panels currently on the market have an efficiency between 15%- 22%. You might think this is a low percentage, but the truth is, it is enough to power your home and sell some of the remaining electricity back to the grid. Grid-connected systems When you are choosing a solar panels system, you will see there are lots of options. One important thing to know is that there are grid-connected and off-the-grid solar systems. The first option is good if you want to benefit from the Feed-in Tariff and also if you want to have access to electricity during the night. Off-the-grid systems are more suitable for cottages that have no access to the national grid, and most often go along with batteries to power the house when there is no sun. Heating or electricity? Despite the fact that “solar panels” is the most common term to refer to solar power, one must know that solar panels (or solar photovoltaics) are different from solar water heating systems (or solar thermal systems). While solar panels generate electricity and make it available for household use, solar thermal systems are used to heat water, which is then available for heating purposes in the house. Inverter A solar inverter is also called “the brain“ of the solar system. This device will convert the energy captured during the day, from DC to AC, so it can be used for consumption. The inverter combines digital control technology with efficient power conversion architecture in order to make the most of the energy the panels are collecting. You can choose from grid-tie or off-grid inverters. ”Smart inverters” are being developed with forecasting algorithms, load/demand planning and so on. In addition, smart inverters can be “told” whether to use photovoltaic energy or not, send power to batteries to store it, or save you in case of a power blackout. Ja, Panasonic, Samsung, REC, Sunpower Are just a few brand names that manufacture solar panels. The major players in the market are competing to bring great features for the consumers such as double sided panels or anti reflective coating. A large amount of resources is invested every year in Research and Development. It is good to have an idea of the different brands in the market, and maybe read a little description of the differences and advantages of each. You can find a lot of detailed information here: Buyers-guide-to-solar-panels Kilowatts You can find it on your monthly electricity bill. They will indicate the amount of electricity you have used. It is always a good starting point to find your energy bills from the last year so you and the solar supplier have a good understanding of your energy use and costs. From this step you can start planning what kind of panels and how many you need. Check with the manufacturer to find out how many kW you can expect the panels to generate. Long term savings Solar panels are said to be expensive. And it’s true that the initial costs are considerable (although technological development has lead to an abrupt drop in the costs of solar devices). However, like it happens with any other big investment, one should assess the costs/benefits in the long term. The cost of a solar panel installation can go from £2,500 to £8,000 depending on the type of system chosen. If you are eligible for the Feed-in Tariff, this will payback after approximately 8 years (remember that during all this time you will enjoy the free electricity). Monocrystalline solar cells Made from the purest form of silicone, these cells deliver the highest efficiencies. One crystal of silicon is used to make one cell. You can recognize them by the uncovered gaps at the four corners of the cells. apart from monocrystalline cells, you can also choose polycrystalline or thin-film panels. Normal Operating Test Conditions (NOCT) are used to measure the solar panel's output under “real world” conditions. This will indicate how much power you can expect the panels to generate on any given day. Initially, the panels are tested under Standard Test Conditions (STC). This is a lab carried test, where the conditions are optimal. However, a solar system will produce lower energy when faced with changes in: weather, shading, irradiance. NOCT assumes the following: irradiance 800 W/㎡, ambient temperature 20°C, windspeed 1m/s, nominal cell temperature 45.7°C (±2°C). So when you read the data sheet of a solar panel, look for the output under NOCT. Photovoltaic "Photo" comes from the Greek language, and means "light"; and "voltaic", means electric, and comes from the name of the Italian physicist Volta. Often, solar panels are also called photovoltaics or solar PV’s. Rent a roof scheme Some installers run this business model which consists of installing a free solar panel system on your roof. In this scenario, you rent your roof in exchange of free (and clean) electricity generated by the panel. The catch is that the excess electricity the panels produce will be sold to the grid and the money will be cashed in by the installer. If you decide to get the free panels you should know that you and the installer will enter a 25-year commitment contract. Also, you need to own your home and your roof must usually be 24 square meters due south, or within 35 degrees of south. Technical information The solar cell is the main component of Photovoltaic technology and Solar PV systems use these cells to convert solar radiation into electricity. Solar cells consist of one or two layers of a semi-conductor and the most common material used in these cells is silicon, an abundant element most commonly found in sand. Watch how solar panels are made. Solar cells can be wired together to form a module (a solar panel) and these can then be connected together to form an array. More than one array connected together will form a solar system. In addition, a solar panel can weigh from 15Kg to 26Kg, and their dimensions go from 99x140cm to 105x166cm. Moreover, you should know that maximum output (expressed in Watts) is the amount of power a sun panel will generate. Unlimited energy The big advantage of solar energy compared with other sources of energy is that the energy of the sun is unlimited. In addition, solar energy is not only a clean and free source of energy, but also a different way to make money. Installing solar panels in your roof will therefore reduce your carbon footprint and also reduce your electricity bills since you will use less energy from your supplier. In addition, if you are eligible for the Feed-in Tariff, you can even get paid for the green electricity you produce. Here you can see a simple explanation of the carbon footprint. V is for very easy! Switching to solar energy is very easy once you find the right installer. Finding the right installer is not complicated either. As previously mentioned, you can get free quotes and compare the offers from different installers. You can also ask for references if you have neighbours that have already taken the lead. When you have the installer, it’s just about making the investment and enjoying for the next decades the free and green electricity from your panels. Warranty of solar panels Typically, most manufacturers offer 2 kinds of warranty: one for the product one for the output It is common to get a 10-year material and workmanship warranty. When it comes to output, most manufacturers will cover 25 years. You should check with the manufacturer how much of the output they will actually cover. For example, you could expect 97% of the maximum output in the first year of operation. This will gradually decrease with 0.7% every year reaching around 80% in year 25. X-ample Xavier has a 4kW Solar PV installation at his bungalow, in Bournemouth. The 16 solar panel system generates 3500 kWh per year in green energy. After the first month, he started to save £50 on his electricity bill. After 3 months, the first cheque came in with payments from the Feed-in Tariff- this time £200. Xavier now covers 80% of the electricity he consumes with the help of solar panels. The payback period for this project is 6.5 years but payments from the FIT will come for the next 20 years. You should get solar panels! There’s not much to explain here. It is easy, it is good for the environment, and it is also good from a financial point of view.

Clearflo Ag-47 Antimicrobial PVC Tubing

 

Fri, 06/05/2015 - 10:36am NewAge Industries Inc. New from tubing manufacturer NewAge Industries is Clearflo Ag-47 antimicrobial tubing. Suitable for a variety of fluid transfer applications, Clearflo Ag-47 is designed to protect liquids from harmful bacteria that can result in taste transfer, odors and illnesses. Clearflo Ag-47 is manufactured from a clear, flexible PVC compound that is free of phthalates. It contains a silver ion additive, tested in accordance with ISO 22196:2011 on over 50 different species of bacteria, to guard against microorganisms such as E. coli, listeria, salmonella, legionella, MRSA, campylobacter and pseudomonas. The silver ion ingredient is throughout the tubing, not only on the interior as with similar products, for bacteria protection on all tubing surfaces. The transparent tubing handles temperatures between -40 F and 125 F (-40 C and 52 C) and is stocked and immediately available in ten sizes ranging from 3/16 in through 1/2 in I.D. NewAge Industries, www.newageindustries.com

Toward “green” paper-thin, flexible electronics

 

Wed, 06/10/2015 - 9:15am American Chemical Society A new, environmentally friendly paper that glows could lead to sustainable, roll-up electronics. Image: American Chemical SocietyThe rapid evolution of gadgets has brought us an impressive array of “smart” products from phones to tablets, and now watches and glasses. But they still haven’t broken free from their rigid form. Now scientists are reporting in ACS Applied Materials & Interfaces a new step toward bendable electronics. They have developed the first light-emitting, transparent and flexible paper out of environmentally friendly materials via a simple, suction-filtration method. Technology experts have long predicted the coming age of flexible electronics, and researchers have been working on multiple fronts to reach that goal. But many of the advances rely on petroleum-based plastics and toxic materials. Yu-Zhong Wang, Fei Song and colleagues wanted to seek a “greener” way forward. The researchers developed a thin, clear nanocellulose paper made out of wood flour and infused it with biocompatible quantum dots—tiny, semiconducting crystals—made out of zinc and selenium. The paper glowed at room temperature and could be rolled and unrolled without cracking. Source: American Chemical Society

Heart attack risk increases 16-21% with use of common antacid

 

Recent studies show increased risk of heart attack for people who use proton pump inhibitors to control GERD and other excess-acid issues. Adults who use proton pump inhibitors are between 16 and 21 percent more likely to experience a heart attack than people who don't use the commonly prescribed antacid drugs, according to a massive new study by Houston Methodist and Stanford University scientists. An examination of 16 million clinical documents representing 2.9 million patients also showed that patients who use a different type of antacid drug called an H2 blocker have no increased heart attack risk. The findings, reported in PLOS ONE, follow a Circulation report in 2013 in which scientists showed how -- at a molecular level -- PPIs might cause long-term cardiovascular disease and increase a patient's heart attack risk. "Our earlier work identified that the PPIs can adversely affect the endothelium, the Teflon-like lining of the blood vessels," said John Cooke, M.D., Ph.D., a senior author of the PLOS ONE report. "That observation led us to hypothesize that anyone taking PPIs may be at greater risk for heart attack. Accordingly, in two large populations of patients, we asked what happened to people that were on PPIs versus other medications for the stomach." The PLOS ONE study's principal investigator was Stanford vascular medicine specialist Nicholas J. Leeper, M.D. In the present study, the researchers found a clear and significant association between exposure to PPIs and the occurrences of heart attack. "By looking at data from people who were given PPI drugs primarily for acid reflux and had no prior history of heart disease, our data-mining pipeline signals an association with a higher rate of heart attacks," said the PLOS ONE report's lead author, Nigam H. Shah, M.B.B.S., Ph.D., an assistant professor of biomedical informatics at Stanford, where the work was done. "Our results demonstrate that PPIs appear to be associated with elevated risk of heart attack in the general population, and H2 blockers show no such association." The estimated increase of heart attack risk ranges from 16 to 21 percent, because of uncertainty in the estimation process, Shah said. The FDA estimates about 1 in 14 Americans has used proton pump inhibitors. In 2009, PPIs were the third-most taken type of drug in the U.S., and are believed to account for $13 billion in annual global sales. Doctors prescribe PPIs to treat a wide range of disorders, including gastro-esophageal reflux disease, or GERD, infection by the ulcer-causing bacterium Helicobacter pylori, Zollinger-Ellison syndrome, and Barrett's esophagus. The drugs can also be purchased over the counter. PPIs come in a variety of slightly different chemical forms, always ending with the suffix "-prazole," for example, omeprazole or lansoprazole. Brand examples of PPIs are Nexium, Prilosec, and PrevAcid. H2 blockers are another type of antacid drug. They are not believed to be associated with increased risk of heart attack or cardiovascular disease. Examples of the drug are cimetidine and ranitidine. Brand examples of H2 blockers are Zantac and Tagamet. The researchers collected data from two repositories -- STRIDE (Stanford Translational Research Integrated Database Environment), which contains information about 1.8 million Stanford hospital and clinic patients, and a subset of information for 1.1 million patients from the Web-based electronic medical records company Practice Fusion, Inc. Both sources of patient information were anonymized before the researchers accessed the data. The group scanned the databases for patients who were prescribed proton pump inhibitors or other drugs, such as H2 blockers, and also looked to see if a given patient had a mention of having experienced a major cardiovascular event, such as myocardial infarction (heart attack), in their medical record. Patients who had used PPIs were found to be at 1.16-1.21-fold-increased risk of heart attack. Scrutiny of PPIs has only increased with time. Initially it was believed PPIs only posed a risk to a very narrow subset of patients -- those with coronary artery disease who were using the anti-platelet drug clopidogrel to prevent future heart attacks. "Investigators originally assumed this was due to a drug-drug interaction between these compounds, and the FDA went so far as to release a warning about their concomitant use," said Nicholas Leeper. A 2013 report to Circulation by several of the present report's coauthors, including Cooke, raised the possibility that PPIs could lead to cardiovascular disease in the general population. "This led us to use powerful 'big-data' approaches to try to determine whether PPIs might in fact be associated with risk in 'all comers,' Leeper said. "Our report raises concerns that these drugs -- which are available over the counter and are among the most commonly prescribed drugs in the world -- may not be as safe as we previously assumed." In the future, the researchers say they hope to conduct a large, prospective, randomized trial to determine whether PPIs are harmful to a broader population of patients. Story Source: The above story is based on materials provided by Houston Methodist. Note: Materials may be edited for content and length. Journal Reference: Nigam H. Shah, Paea LePendu, Anna Bauer-Mehren, Yohannes T. Ghebremariam, Srinivasan V. Iyer, Jake Marcus, Kevin T. Nead, John P. Cooke, Nicholas J. Leeper. Proton Pump Inhibitor Usage and the Risk of Myocardial Infarction in the General Population. PLOS ONE, 2015; 10 (6): e0124653 DOI: 10.1371/journal.pone.0124653

3D printing with metals achieved

 

Wed, 06/10/2015 - 9:25am University of Twente A copper micro-pillar with a height of 0.86 mm and a width of 0.005 mm. The pillar is formed from drops that had a diameter of 0.001 mm. With this technique, more complex shapes can also be printed. A team of researchers from the Univ. of Twente has found a way to 3D print structures of copper and gold, by stacking microscopically small metal droplets. These droplets are made by melting a thin metal film using a pulsed laser. Their work is published by Advanced Materials. 3D printing is a rapidly advancing field, that is sometimes referred to as the “new cornerstone of the manufacturing industry”. However, at present, 3D printing is mostly limited to plastics. If metals could be used for 3D printing as well, this would open a wide new range of possibilities. Metals conduct electricity and heat very well, and they're very robust. Therefore, 3D printing in metals would allow manufacturing of entirely new devices and components, such as small cooling elements or connections between stacked chips in smartphones. However, metals melt at a high temperature. This makes controlled deposition of metal droplets highly challenging. Thermally robust nozzles are required to process liquid metals, but these are hardly available. For small structures in particular (from 100 nm to 10 um) no good solutions for this problem existed yet. Researchers from FOM and the Univ. of Twente now made a major step towards high-resolution metal printing. They used laser light to melt copper and gold into micrometer-sized droplets and deposited these in a controlled manner. In this method, a pulsed laser is focused on a thin metal film that locally melts and deforms into a flying drop. The researchers then carefully position this drop onto a substrate. By repeating the process, a 3-D structure is made. For example, the researchers stacked thousands of drops to form micro-pillars with a height of 2 mm and a diameter of 5 um. They also printed vertical electrodes in a cavity, as well as lines of copper. In effect, virtually any shape can be printed by smartly choosing the location of the drop impact. High energy In this study, the researchers used a surprisingly high laser energy in comparison to earlier work, to increase the impact velocity of the metal droplets. When these fast droplets impact onto the substrate, they deform into a disk shape and solidify in that form. The disk shape is essential for a sturdy 3D print: It allows the researchers to firmly stack the droplets on top of each other. In previous attempts, physicists used low laser energies. This allowed them to print smaller drops, but the drops stayed spherical, which meant that a stack of solidified droplets was less stable. In their article, the researchers explain which speed is required to achieve the desired drop shape. They had previously predicted this speed for different laser energies and materials. This means that the results can be readily translated to other metals as well. One remaining problem is that the high laser energy also results in droplets landing on the substrate next to the desired location. At present this cannot be prevented. In future work the team will investigate this effect, to enable clean printing with metals, gels, pastas or extremely thick fluids. Source: University of Twente

Boron compounds for OLEDs

 

Wed, 06/10/2015 - 11:15am Goethe University. Frankfurt Image: GUMajor Customized organic molecules enable the production of lightweight, mechanically flexible electronic components that are perfectly adapted to individual applications are shown. advances in the field of organic electronics are currently revolutionizing previously silicon-dominated semiconductor technology. Customized organic molecules enable the production of lightweight, mechanically flexible electronic components that are perfectly adapted to individual applications. Chemists at the Goethe Univ. have now developed a new class of organic luminescent materials through the targeted introduction of boron atoms into the molecular structures. The compounds described in Angewandte Chemie feature an intensive blue fluorescence and are therefore of interest for use in organic light-emitting diodes (LED's). Carbon in the form of graphite conducts the electrical current in a similar way to a metal. In addition, its two-dimensional shape, the graphene layer, has extremely attractive optical and electronic properties. In graphene, the discoverers of which were awarded the Nobel Prize for Physics in 2010, countless benzene rings are fused to form a honeycomb structure. Sections of this structure, so-called nanographenes or Polycyclic Aromatic Hydrocarbons (PAHs), constitute an important basis of organic electronics. "For a long time, efforts were largely focused on affecting the properties of nanographenes by chemically manipulating their edges", according to Prof. Matthias Wagner of the Institute for Inorganic and Analytical Chemistry at the Goethe University. "However, in recent years, researchers have been increasingly capable of also modifying the inner structure by embedding foreign atoms in the carbon network. This is where boron assumes crucial significance." A comparison of the new boron-containing nanographenes with the analogous boron-free hydrocarbons verifies the fact that the boron atoms have a decisive impact on two key properties of an OLED luminophore: The fluorescence color shifts into the highly desirable blue spectral range and the capacity to transport electrons is substantially improved. To date, only limited use could be made of the full potential of boron-containing PAHs, since most of the exponents are sensitive to air and moisture. "This problem does not occur with our materials, which is important with regard to practical applications" explains Valentin Hertz, who synthesized the compounds within the scope of his doctoral dissertation. Hertz and Wagner anticipate that materials such as the graphene flakes they have developed will be particularly suitable for use in portable electronic devices. As film displays for future generations of smartphones and tablets, even large-scale screens could be rolled up or folded to save space when the devices are not in use.