OREGON STATE UNIVERSITY

engineering and technology

Alloying materials of different structures offers new tool for controlling properties

CORVALLIS, Ore. – New research into the largely unstudied area of heterostructural alloys could lead to greater materials control and in turn better semiconductors, advances in nanotechnology for pharmaceuticals and improved metallic glasses for industrial applications.

Heterostructural alloys are blends of compounds made from materials that don’t share the same atom arrangement. Conventional alloys are isostructural, meaning the compounds they consist of, known as the end members, have the same crystal structure.

“Alloys are all around us,” said study co-author Janet Tate, a physicist at Oregon State University. “An example of an istostructural alloy is an LED; you have a semiconductor like aluminum gallium arsenide, dope it with a particular material and make it emit light, and change the color of the light by changing the relative concentration of aluminum and gallium.”

Structure and composition are the two means of controlling the behavior of materials, Tate said. Combining materials gives the alloy properties between those that the end members have individually.

“If two materials have different structures, as you mix them together it’s not so clear which structure will win,” said Tate, the Dr. Russ and Dolores Gorman Faculty Scholar in the College of Science. “The two together want to take different structures, and so this is an extra way of tuning an alloy’s properties, a structural way. The transition between different crystal structures provides an additional degree of control.”

Tate and collaborators from around the world, including the National Renewable Energy Laboratory, published their findings in Science Advances.

“This is a very interesting piece of materials science that represents a somewhat uncharted area and it may be the beginning something quite important,” Tate said. “The heterostructural alloy concept had been known before, but it’s different enough that it hadn’t really been explored in a detailed phase diagram – the mapping of exactly how, at what temperature and what concentration, it goes from one structure to another.

“This paper is primarily the NERL’s theoretical work being supported by other collaborators’ experimental work,” Tate said. “Our involvement at OSU was in making one of the kinds of heterostructural alloys used in the research, the combination of tin sulfide and calcium sulfide.”

Tate and graduate student Bethany Matthews have been focusing on the semiconductor application.

“Tin sulfide is a solar cell absorber, and the addition of calcium sulfide changes the structure and therefore the electrical properties necessary for an absorber,” Tate said “Combining tin sulfide with calcium sulfide makes it more isotropic – properties being the same regardless of orientation – and that’s usually a useful thing in devices.”

In this study, thin-film synthesis confirmed the metastable phases of the alloys that had been predicted theoretically.

“Many alloys are metastable, not stable – if you gave them enough time and temperature, they’d eventually separate,” Tate said. “The way we make them, with pulsed laser deposition, we allow the unstable structure to form, then suppress the decomposition pathways that would allow them to separate; we don’t give them enough time to equilibrate.”

Metastable materials – those that are thermodynamically stable provided they are not subjected to large disturbances – are in general understudied, Tate said.

“When theorists predict properties, they tend to work with materials that are stable,” she said. “In general the stable compounds are easier to attack. The idea here with heterostructural alloys is that they give us a new handle, a new knob to turn to change and control materials’ properties.”

In addition to scientists at the National Renewable Energy Laboratory, the collaboration included researchers at the University of Colorado, the Colorado School of Mines, the SLAC National Accelerator Laboratory, and Harvard University.

The U.S. Department of Energy supported this research.

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Steve Lundeberg, 541-737-4039

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Northwest researchers map out regional approach to studying food, energy, water nexus

CORVALLIS, Ore. – Natural resource researchers at Oregon State University, Washington State University and the University of Idaho are gearing up for a late-summer summit aimed at addressing food, energy and water challenges as interconnected, regional issues.

The August meeting in Hermiston, Ore. – centrally located to many National Science Foundation-funded research projects – represents the second step of a collaboration that began with an April workshop in Coeur d’Alene, Idaho.

Research offices at the three universities hosted the gathering, where scientists explored ways to partner with each other and with industry to address issues that affect regional economies as well as environmental and human health.

Stephanie Hampton from WSU and Andrew Kliskey from Idaho led the planning of the workshop, at which six teams combined to start five U.S. Department of Agriculture and NSF grant proposals on issues ranging from water conservation to energy infrastructure.

“We’re really building a critical mass of researchers and research experience in the region,” said Chad Higgins, an agricultural engineering professor leading OSU’s role in the partnership. “The workshop was awesome. It exceeded all expectations with mind-blowing scientific discussions, new collaborations formed and new proposals floated. And now we have to keep it going because that was just the opening salvo, not the crescendo.”

Topics for future exploration might be broad – such as, will the region have enough food in 2050? – or narrow, like tracing the impact of a single technology. For example, a more efficient system for irrigation could lead to less energy used for pumping and also result in more food being produced.

“The food, energy, water nexus is so huge that it’s scary, but it’s also exciting,” Higgins said. “There are so many opportunities to look at things either in detail or to try to be broad and think about how the region will be influenced. We can bring each person’s expertise together to predict pain points, like are we going to be scarce in any one resource in the future, and where?”

Janet Nelson, vice president for research and economic development at the University of Idaho, said the tri-state collaboration “will poise us to build relationships among researchers from all three universities with many areas of expertise in order to work toward solutions that improve communities, economies and lives.”

“The University of Idaho is committed to examining issues that are critical not only to the people of Idaho, but also to the entire Northwest region, with rippling effects around the world,” she said.

Those issues include how to best update aging hydropower plants and food production infrastructure.

Cynthia Sagers, vice president for research at Oregon State, notes that when it comes to food, energy and water challenges, a solution in one location can lead to problems hundreds of miles away.

“That’s why this demands regional cooperation,” she said. “I am proud that our three land grant institutions are working together on these issues for a healthy Pacific Northwest." 

Christopher Keane, vice president of research at WSU, echoed the sentiment and said he “looks forward to seeing the results of continued collaboration.”

“Working across disciplines and institutions to ensure a sustainable supply of food, energy and water for future generations is a top research priority for WSU,” he said.

In addition to the August event, the planning team is applying for external funding to support ongoing meetings to help sustain momentum. 

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Sunflower crop

OSU College of Engineering establishes institute for robotics, intelligent systems

CORVALLIS, Ore. – Oregon State University’s College of Engineering has established a new research institute to advance the theory, design, development and deployment of robots and intelligent systems able to interact seamlessly with people.

It’s called the CoRIS Institute, short for Collaborative Robotics and Intelligent Systems.

Institute director Kagan Tumer said the new center would conduct research in robotics and artificial intelligence, as well as machine learning, vision, sensors, devices, and new materials. The institute also will explore public policy and ethical questions surrounding the deployment of robots and intelligent systems.

Tumer said the institute would enable research in oceanography, forestry, agricultural science and other fields, as well as identify and facilitate possible partnerships with companies around the globe to bring algorithms, software, hardware and integrated systems into everyday use.

“The CoRIS Institute will cement Oregon State’s position as a national leader in robotics and artificial intelligence,” said Scott Ashford, dean of the College of Engineering.

“The institute is poised to become a venue for exploring not just the technological advancement of robotics, but also all of the other dimensions of the robotics revolution. It will investigate the promise and the risks of robotics in the real world today, tomorrow and well into the future and help us plot a course through uncharted territory.”

The college offers a top-tier artificial intelligence program, as well as one of the five doctorate-granting robotics programs in the U.S. Those two programs received more than 500 student applications for the 40 openings available in fall term 2016.

“Our robotics and artificial intelligence faculty have a strong reputation for conducting cutting-edge research, holding key leadership positions in international organizations and drawing the best students from Oregon, the nation and the world,” said Tumer, a professor of mechanical engineering with a background that spans computer science and electrical engineering. “Research at Oregon State focuses on robotics and intelligent systems as a whole, exploring both the interaction between technology and human beings and the impact that technology will have on society.”

The institute’s core faculty are 25 researchers in robotics and artificial intelligence. Collaborators include more than 40 other researchers from across OSU who are looking to apply robotics and AI concepts to their own work.

“I can think of no better place than Oregon State for the home of the new CoRIS Institute,” Ashford said. “Our visionary robotics program already is recognized as one of the nation’s best and most progressive, and OSU’s deeply rooted culture of collaboration provides an ideal environment for this interdisciplinary institute to thrive and grow.”

Tumer notes that the moment a robot exits a lab and enters the everyday world, the large, complicated issue of human-robot interaction is at play in full force.

“You have to look at the big picture,” he said. “You have to think about how that robot is going to interact with people months down the road, years down the road. There are technical issues to putting robots in homes and also ethical issues. For example, what are the privacy issues of having a robot in your home 24-7? What is the emotional impact of interacting with that robot daily? It’s fair to say our emphasis on societal impact is one of the unique aspects of our institute.”

Early on in the field of robotics, Tumer said, a robot was typically a “big mechanical device on a factory floor, caged away, unpredictable and dangerous, not designed to be interacting with humans in a way that was natural to them.”

“But in the future, a robot might be sitting with you, working with you with some level of interaction,” he said. “Oregon State didn’t have a robotics program 10 years ago, which is in some ways liberating because we’re not saddled with the legacy of what a robotics program ought to be. We have a lot of young faculty who are looking at where the field is going and are not in any way stuck with how things were perceived in past. They’re looking at how robotics ought to be rather than how robotics was.”

Tumer’s leadership team includes three associate directors: Julie A. Adams, for deployment and policy; Alan Fern, for research; and Bill Smart, for academics. Adams and Fern are professors of computer science, and Smart is an associate professor of mechanical engineering.

Funding sources for research by the institute’s core faculty include federal and state grants, industry grants, and philanthropic gifts.

The institute will be located within existing research space within the College of Engineering.

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Steve Lundeberg, 541-737-4039

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Cassie the robot

Research aims to protect eagles from wind turbines

CORVALLIS, Ore. – New research from Oregon State University will aim to make eagles less likely to collide with wind-turbine blades.

The U.S. Department of Energy Wind Technology Office has awarded Roberto Albertani of the OSU College of Engineering a 27-month, $625,000 grant to develop technology for detecting and deterring approaching eagles and for determining if a blade strike has occurred.

A growing energy source in the U.S., wind power uses towers up to 300 feet tall typically equipped with three blades with wingspans double that of a Boeing 747. At their tips, the blades are moving close to 200 miles per hour.

Wind power is generally regarded as green energy, but danger to birds – particularly bald eagles and golden eagles – is a concern.

Albertani’s team will work on a three-part system for protecting the eagles. “We’re the only team in the world doing this kind of work,” said Albertani, an associate professor of mechanical engineering.

The team includes Sinisa Todorovic, associate professor of computer science, and Matthew Johnston, assistant professor of electrical and computer engineering.

If successful, Albertani said, the system that he and his colleagues develop will be a major breakthrough in a safer-for-wildlife expansion of wind energy worldwide.

The system will feature a tower-mounted, computer-connected camera able to determine if an approaching bird is an eagle and whether it’s flying toward the blades. If both those answers are yes, the computer triggers a ground-level deterrent: randomly moving, brightly colored facsimiles of people, designed to play into eagles’ apparent aversion to humans.

“There’s no research available, but hopefully those will deter the eagles from coming closer to the turbines,” Albertani said. “We want the deterrent to be simple and affordable.”

At the root of each turbine blade will be a vibration sensor able to detect the kind of thump produced by a bird hitting a blade. Whenever such a thump is detected, recorded video data from a blade-mounted micro-camera can be examined to tell if the impact was caused by an eagle or something else.

“If we strike a generic bird, sad as that is, it’s not as critical as striking a protected golden eagle, which would cause the shutdown of a wind farm for a period of time, a fine to the operator, big losses in revenue, and most important the loss of a member of a protected species,” Albertani said.

Albertani’s team includes two collaborators from the U.S. Geological Survey, biological statistician Manuela Huso and wildlife biologist and eagle expert Todd Katzner. An external advisory board includes Siemens Wind Power and Avangrid Renewables.

Primary field testing will take place at the North American Wind Research and Training Center in Tucumcari, N.M., and the NREL National Wind Technology Center in Boulder, Colo. Field work will also be done in Oregon and California.

The U.S. Fish and Wildlife Service estimates there are roughly 143,000 bald eagles and 40,000 golden eagles in the United States.

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Wind turbines

Technology to improve rockfall analysis on cliffs could save money, lives

CORVALLIS, Ore. – Researchers in the Pacific Northwest have developed a new, automated technology to analyze the potential for rockfalls from cliffs onto roads and areas below, which should speed and improve this type of risk evaluation, help protect public safety and ultimately save money and lives.

Called a “rockfall activity index,” the system is based on the powerful abilities of light detection and ranging, or LIDAR technology. It should expedite and add precision to what’s now a somewhat subjective, time-consuming process to determine just how dangerous a cliff is to the people, vehicles, roads or structures below it.

This is a multi-million dollar global problem, experts say, of significant concern to transportation planners.

It’s a particular concern in the Pacific Northwest with its many mountain ranges, heavy precipitation, erosion of steep cliffs and unstable slopes, and thousands of roads that thread their way through that terrain. The evaluation system now most widely used around the world, in fact, was developed by the Oregon Department of Transportation more than 25 years ago.

The new technology should improve on that approach, according to scientists who developed it from the University of Washington, Oregon State University and the University of Alaska Fairbanks. Findings on it were just published in Engineering Geology.

“Rockfalls are a huge road maintenance issue,” said Michael Olsen, an associate professor of geomatics in the College of Engineering at Oregon State University, and co-author of the report.

“Pacific Northwest and Alaskan highways, in particular, are facing serious concerns for these hazards. A lot of our highways in mountainous regions were built in the 1950s and 60s, and the cliffs above them have been facing decades of erosion that in many places cause at least small rockfalls almost daily. At the same time traffic is getting heavier, along with increasing danger to the public and even people who monitor the problem.”

The new approach could replace the need to personally analyze small portions of a cliff at a time, looking for cracks and hazards, with analysts sometimes even rappelling down it to assess risks. LIDAR analysis can map large areas in a short period, and allow data to be analyzed by a computer.

“Transportation agencies and infrastructure providers are increasingly seeking ways to improve the reliability and safety of their systems, while at the same time reducing costs,” said Joe Wartman, associate professor of civil and environmental engineering at the University of Washington, and corresponding author of the study.

“As a low-cost, high-resolution landslide hazard assessment system, our rockfall activity index methodology makes a significant step toward improving both protection and efficiency.”

The study, based on some examples in southern Alaska, showed the new system could evaluate rockfalls in ways that very closely matched the dangers actually experienced. It produces data on the “energy release” to be expected from a given cliff, per year, that can be used to identify the cliffs and roads at highest risk and prioritize available mitigation budgets to most cost-effectively protect public safety.

“This should improve and speed assessments, reduce the risks to people doing them, and hopefully identify the most serious problems before we have a catastrophic failure,” Olsen said.

The technology is now complete and ready for use, researchers said, although they are continuing to develop its potential, possibly with the use of flying drones to expand the data that can be obtained.

Tens of millions of dollars are spent each year in the U.S. on rock slope maintenance and mitigation.

This research was supported by the Pacific Northwest Transportation Consortium, the National Science Foundation and the Alaska Department of Transportation and Public Facilities. Co-authors included Lisa Dunham, former civil and environmental engineering graduate student at the University of Washington; graduate assistant Matthew O’Banion at OSU; and Keith Cunningham, research assistant professor of remote sensing at the University of Alaska Fairbanks.

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Michael Olsen, 541-737-9327

michael.olsen@oregonstate.edu

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A crumbling cliff
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Agility Robotics evolves from OSU research, aims to revolutionize robot mobility

CORVALLIS, Ore. – The rapidly expanding robotics program in the College of Engineering at Oregon State University has spun off one of its first businesses, a company focused on legged locomotion that may revolutionize robot mobility and enable robots to go anywhere people can go.

The firm, Agility Robotics, is based in Albany, Oregon, and Pittsburgh, Pennsylvania; already has several of its first customers; will license some technologies first developed at OSU, and plans to build on this scientific foundation in their product research and development.

A leading application for this type of mobility is package delivery, company officials say. In the long term, advanced mobility will enable shipping so automated and inexpensive that its cost becomes inconsequential, opening vast new possibilities in retail trade while lowering costs for manufacturing and production.

“This technology will simply explode at some point, when we create vehicles so automated and robots so efficient that deliveries and shipments are almost free,” said Jonathan Hurst, an associate professor of robotics in the OSU College of Engineering, chief technology officer at Agility Robotics and an international leader in the development of legged locomotion.

“Quite simply, robots with legs can go a lot of places that wheels cannot. This will be the key to deliveries that can be made 24 hours a day, 365 days a year, by a fleet of autonomous vans that pull up to your curb, and an onboard robot that delivers to your doorstep.

“This robot capability will free people from weekend shopping chores, reduce energy use, and give consumers more time to do the things they want to do. It effectively brings efficient automated logistics from state-of-the-art warehouses out and into the rest of the world.”

This long-term vision will take many steps, company officials said.

Some of Agility Robotics’ first sales will be to other academic and research institutions, to grow the research community and educate a new generation of engineers in this area, company officials said. What the firm now offers is a bipedal robot named “Cassie” – similar to the prototype version demonstrated Feb. 8 at OSU’s State of the University address in Portland, Oregon, by President Edward J. Ray.

Cassie the robot can stand, steer, and take a pretty good fall without breaking. It’s half the weight and much more capable than earlier robots developed at OSU.

“Our previous robot, ATRIAS, had motors that would work against either other, which was inefficient,” Hurst said. “With Cassie, we’ve fixed this problem and added steering, feet, and a sealed system, so it will work outdoors in the rain and snow as we continue with our controller testing.”

The particular issue of motors working against one another prompted some extensive theoretical research, to create the mathematical frameworks needed to solve the problem. The resulting leg configuration of Cassie looks much like an ostrich or other ground-running bird.

“We weren’t trying to duplicate the appearance of an animal, just the techniques it uses to be agile, efficient and robust in its movement,” Hurst said.

“We didn’t care what it looked like and were mostly just working to find out why Mother Nature did things a certain way. But even though we weren’t trying to mimic the form, what came out on the other end of our research looked remarkably like an animal leg.”

Cassie, built with a 16-month, $1 million grant from the Advanced Research Projects Agency of the U.S. Department of Defense, is already one of the leading innovations in the world of legged robotics.

Company officials say they plan to do all initial production in Oregon and will focus their business on the commercial applications of legged robots. Hiring is anticipated for research, production and development.

“The robotics revolution will bring with it enormous changes, perhaps sooner than many people realize,” Hurst said. “We hope for Agility Robotics to be a big part of that revolution. We want to change people’s lives and make them better.”

 

Company officials said that access to the research base and education of students at OSU will aid its growth, providing the needed expertise and trained work force. OSU has already been ranked by Grad School Hub as the best in the western United States and fourth leading program in the nation in robotics research and education.

Last month, OSU officials also announced that the university will be a founding academic partner in the newest Manufacturing USA Institute, the Advance Robotics Manufacturing Innovation Hub. This broad program with 14 institutes is a $3 billion federal and private company initiative designed to enhance U.S. competitiveness in advanced manufacturing.

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Jonathan Hurst, 541-737-7010

jonathan.hurst@oregonstate.edu

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Off-grid power in remote areas will require special business model to succeed

CORVALLIS, Ore. – Low-cost, off-grid solar energy could provide significant economic benefit to people living in some remote areas, but a new study suggests they generally lack the access to financial resources, commercial institutions and markets needed to bring solar electricity to their communities.

Around the world, more than 1.2 billion people lack access to basic electricity service. The majority of those people are living in developing nations, in rural or isolated areas with high rates of poverty. Steep costs and remote terrain often make it impractical or even impossible to extend the electric grid. 

Developing a successful business model that could deliver off-grid power to this market will require addressing challenges unique to the population, an Oregon State University researcher concluded in a study published recently in Renewable and Sustainable Energy Reviews.

“Surviving and growing in this market is very different than in a typical commercial enterprise,” said Inara Scott, an assistant professor in the College of Business. “There are a lot of people working on off-grid solar products on the small scale, but the problem becomes how can they scale the programs up and make them profitable?” 

When rural, isolated communities do gain access to solar power, the impact on residents can be profound, Scott said. Children are more likely to go to and complete schooling, because they have light to study by. Kerosene lamps, which create a lot of indoor air pollution, are no longer needed, improving people’s health. And work hours are increased, giving people more time to earn money or build home-based businesses.

“Providing electricity starts an incredible cycle of improvement for communities without reliance on charities or government aid,” she said. “There are also environmental benefits to encouraging sustainable development using renewable resources.” 

The market for small solar lighting and charging units has grown dramatically in the last few years, and solar home systems offer cleaner, safer and cheaper lighting over time than kerosene, the primary alternative for lighting in developing nations. But even a small cost can be out of reach for people whose annual incomes are often less than $3,000 per year, Scott said.

She examined successful business models for serving these populations, known as “base of the pyramid” markets, and successful renewable energy enterprises, looking for intersections that might aid businesses looking to market solar energy to base-of-pyramid markets. 

Scott found that a successful enterprise would include four primary components, and she developed a framework around them. Her recommendations:

  • Community interaction: Work with local communities to understand local norms, culture, social issues and economic systems that might influence the effort.
  • Partnerships: Join forces with other companies, government organizations, non-profit groups or non-governmental organizations to share ideas and resources and gain support.
  • Local capacity building: People in the community may lack product knowledge and have little experience with technology, while the community may not have typical distribution channels. Consider the potential customers as both producers and consumers, training local entrepreneurs as distributors, marketers and equipment installation/repair technicians.
  • Barriers unique to the off-grid market: Address issues such as financing of upfront costs, which may be prohibitive to consumers; educate people on the products and their benefits; build trust in quality and reliability; and develop multiple strong distribution networks.

“You’re not going to be successful just trying to sell a product,” she said. “This is really a social enterprise, with the goal of trying to bring people out of poverty while also emphasizing sustainable development.” 

There are a lot of socially-minded enterprises with good intentions that would like to work in these rural, remote and high-poverty areas, Scott noted. Her framework could serve as a checklist of sorts for organizations looking to put their ideas into action, she said.

“It’s a way to pause for a minute and ask yourself if you have all the right pieces in place to be successful,” she said.

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Inara Scott, 541-737-4102, Inara.Scott@oregonstate.edu

Advance in intense pulsed light sintering opens door to improved electronics manufacturing

CORVALLIS, Ore. – Faster production of advanced, flexible electronics is among the potential benefits of a discovery by researchers at Oregon State University’s College of Engineering.

Taking a deeper look at photonic sintering of silver nanoparticle films – the use of intense pulsed light, or IPL, to rapidly fuse functional conductive nanoparticles – scientists uncovered a relationship between film temperature and densification. Densification in IPL increases the density of a nanoparticle thin-film or pattern, with greater density leading to functional improvements such as greater electrical conductivity.

The engineers found a temperature turning point in IPL despite no change in pulsing energy, and discovered that this turning point appears because densification during IPL reduces the nanoparticles’ ability to absorb further energy from the light.

This previously unknown interaction between optical absorption and densification creates a new understanding of why densification levels off after the temperature turning point in IPL, and further enables large-area, high-speed IPL to realize its full potential as a scalable and efficient manufacturing process.

Rajiv Malhotra, assistant professor of mechanical engineering at OSU, and graduate student Shalu Bansal conducted the research. The results were recently published in Nanotechnology.

“For some applications we want to have maximum density possible,” Malhotra said. “For some we don’t. Thus, it becomes important to control the densification of the material. Since densification in IPL depends significantly on the temperature, it is important to understand and control temperature evolution during the process. This research can lead to much better process control and equipment design in IPL.”

Intense pulsed light sintering allows for faster densification – in a matter of seconds – over larger areas compared to conventional sintering processes such as oven-based and laser-based. IPL can potentially be used to sinter nanoparticles for applications in printed electronics, solar cells, gas sensing and photocatalysis.

Earlier research showed that nanoparticle densification begins above a critical optical fluence per pulse but that it does not change significantly beyond a certain number of pulses.

This OSU study explains why, for a constant fluence, there is a critical number of pulses beyond which the densification levels off.

“The leveling off in density occurs even though there’s been no change in the optical energy and even though densification is not complete,” Malhotra said. “It occurs because of the temperature history of the nanoparticle film, i.e. the temperature turning point. The combination of fluence and pulses needs to be carefully considered to make sure you get the film density you want.”

A smaller number of high-fluence pulses quickly produces high density. For greater density control, a larger number of low-fluence pulses is required.

“We were sintering in around 20 seconds with a maximum temperature of around 250 degrees Celsius in this work,” Malhotra. “More recent work we have done can sinter within less than two seconds and at much lower temperatures, down to around 120 degrees Celsius. Lower temperature is critical to flexible electronics manufacturing. To lower costs, we want to print these flexible electronics on substrates like paper and plastic, which would burn or melt at higher temperatures. By using IPL, we should be able to create production processes that are both faster and cheaper, without a loss in product quality.”

Products that could evolve from the research, Malhotra said, are radiofrequency identification tags, a wide range of flexible electronics, wearable biomedical sensors, and sensing devices for environmental applications.

The advance in IPL resulted from a four-year, $1.5 million National Science Foundation Scalable Nanomanufacturing Grant in collaboration with OSU researchers Chih-hung Chang, Alan Wang and Greg Herman. The grant focuses on overcoming scientific barriers to industry-level nanomanufacturing. Support also came from the Murdock Charitable Trust and the Oregon Nanoscience and Microtechnologies Institute.

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Unsintered, left, and sintered nanoparticles

Chemical trickery corrals ‘hyperactive’ metal-oxide cluster

CORVALLIS, Ore. – After decades of eluding researchers because of chemical instability, key metal-oxide clusters have been isolated in water, a significant advance for growing the clusters with the impeccable control over atoms that’s required to manufacture small features in electronic circuits.

Oregon State University chemists created the aqueous cluster formation process. It yielded a polyoxocation of zinc, aluminum and chromium that is not protected by the organic ligand shell that is usually required to capture such molecules from water.

“Our discovery is exciting in that it provides both new fundamental understanding and new materials, and useful applications are always built on a foundation of fundamental understanding,” said May Nyman, a professor of chemistry at Oregon State.

Metal oxides – compounds produced when metals combine with oxygen – serve a variety of important purposes. For example, titanium dioxide is a catalyst that degrades pollutants, and aluminum oxides and iron oxides are coagulants used as the first step in purifying drinking water.

“Metal oxides influence processes everywhere,” Nyman said. “They control the spread of contaminants in the environment. They are the touchscreen of your cellphone. The metal-oxide cluster forms are in your body storing iron and in plants controlling photosynthesis. Most of these processes are in water. Yet scientists still know so little about how these metal oxides operate in nature, or how we can make them with the absolute control needed for high-performance materials in energy applications.” 

Results of the research by the OSU College of Science’s Center for Sustainable Materials Chemistry were recently published in the journal Chem.

“We devised some synthetic processes so we can trick the clusters into forming,” Nyman said. “The main thing that we do is control the chemistry so the clusters grow not in the solution where they are highly reactive, but only at the surface, where the water evaporates and they instantly crystallize into a solid phase. Once in the solid phase, there’s no danger of reacting and precipitating metal oxide or hydroxide in an uncontrolled way.”

The clusters created in the research are spherical, contain about 100 atoms, and measure 1 nanometer across.

“Once we have synthesized these, we can prepare a solution of them, and they’re all exactly the same size and contain the same number of atoms,” Nyman said. “This gives us control over making very small features.

“The size of the feature is controlled by the size of the cluster. All metals on the periodic table act differently, and only a few have the right chemistry that behaves well enough to yield these clusters. For the rest of them, we need to innovate new chemistries to discover their cluster forms. The transition metals are particularly hard to control, yet they are earth-abundant and some of the most important metals in energy and environmental technologies.”

Metal-oxo clusters are usually isolated from water with ligands – molecules that protect the cluster surface and prevent precipitation of metal hydroxides.

In this study, an OSU team that included graduate students Lauren Fullmer, Sara Goberna-Ferron and Lev Zakharov overcame the need for ligands with a three-pronged strategy: pH-driven hydrolysis by oxidative dissolution of zinc; metal nitrate concentrations 10 times higher than conventional syntheses; and azeotropic evaporation for driving simultaneous cluster assembly and crystallization at the surface of the solution.

Meanwhile, the team’s computational collaborators in Catalonia provided a deeper understanding of the most stable arrangement of metal and oxygen atoms in the cluster.

“Contrary to common cluster growth, the fully assembled cluster is never detected in the reaction solution,” Nyman said. “Because the reactive clusters do not persist in solution, uncontrolled precipitation of metal hydroxide is avoided. In this sense, we have discovered a new way metal oxides can grow.”

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Metal-oxide crystals

Glucose-monitoring contact lens would feature transparent sensor

CORVALLIS, Ore. – Type 1 diabetes patients may one day be able to monitor their blood glucose levels and even control their insulin infusions via a transparent sensor on a contact lens, a new Oregon State University study suggests.

The sensor uses a nanostructured transistor – specifically an amorphous indium gallium oxide field effect transistor, or IGZO FET – that can detect subtle glucose changes in physiological buffer solutions, such as the tear fluid in eyes.

Type 1 diabetes, formerly known as juvenile diabetes, can lead to serious health complications unless glucose levels are carefully controlled. Problems can include retinopathy, blindness, neuropathy, kidney and cardiac disease.

Researchers in the OSU College of Engineering say sensors they fabricated using the IGZO FET will be able to transmit real-time glucose information to a wearable pump that delivers the hormones needed to regulate blood sugar: insulin and glucagon.

The sensor and pump would, in effect, act as an artificial pancreas.

“We have fully transparent sensors that are working,” said Greg Herman, an OSU professor of chemical engineering and corresponding author on this study. “What we want to do next is fully develop the communication aspect, and we want to use the entire contact lens as real estate for sensing and communications electronics.

“We can integrate an array of sensors into the lens and also test for other things: stress hormones, uric acid, pressure sensing for glaucoma, and things like that. We can monitor many compounds in tears – and since the sensor is transparent, it doesn’t obstruct vision; more real estate is available for sensing on the contact lens.”

The FET’s closely packed, hexagonal, nanostructured network resulted from complimentary patterning techniques that have the potential for low-cost fabrication. Those techniques include colloidal nanolithography and electrohydrodynamic printing, or e-jet, which is somewhat like an inkjet printer that creates much finer drop sizes and works with biological materials instead of ink.

The findings by postdoctoral scholar Xiaosong Du, visiting scholar Yajuan Li and,Herman were recently published online in the journal Nanoscale. The Juvenile Diabetes Research Foundation provided primary funding for the research.

Google has been working on a glucose-monitoring contact lens but its version is not fully transparent.

“It’s an amperometric sensor and you can see the chips -- that means it has to be off to the side of the contact lens,” Herman said. “Another issue is the signal is dependent on the size of the sensor and you can only make it so small or you won’t be able to get a usable signal. With an FET sensor, you can actually make it smaller and enhance the output signal by doing this.”

This research builds on earlier work by Herman and other OSU engineers that developed a glucose sensor that could be wrapped around a catheter, such as one used to administer insulin from a pump.

“A lot of type 1 diabetics don’t wear a pump,” Herman said. “Many are still managing with blood droplets on glucose strips, then using self-injection. Even with the contact lens, someone could still manage their diabetes with self-injection. The sensor could communicate with your phone to warn you if your glucose was high or low.”

The transparent FET sensors, Herman said, might ultimately be used for cancer detection, by sensing characteristic biomarkers of cancer risk. Their high sensitivity could also measure things such as pulse rate, oxygen levels, and other aspects of health monitoring that require precise control.

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