Category Archives: energy

Smart windows from Texas (US)

I’ve been waiting for ‘smart’ windows and/or self-cleaning windows since 2008. While this research on ‘smart’ windows at the University of Texas at Austin looks promising I suspect it will be years before these things are in the marketplace. A July 22, 2015 news item on Nanotechnology Now announces the latest research,

Researchers in the Cockrell School of Engineering at The University of Texas at Austin are one step closer to delivering smart windows with a new level of energy efficiency, engineering materials that allow windows to reveal light without transferring heat and, conversely, to block light while allowing heat transmission, as described in two new research papers.

By allowing indoor occupants to more precisely control the energy and sunlight passing through a window, the new materials could significantly reduce costs for heating and cooling buildings.

In 2013, chemical engineering professor Delia Milliron and her team became the first to develop dual-band electrochromic materials that blend two materials with distinct optical properties for selective control of visible and heat-producing near-infrared light (NIR). In a 2013 issue of Nature, Milliron’s research group demonstrated how, using a small jolt of electricity, a nanocrystal material could be switched back and forth, enabling independent control of light and energy.

A July 23, 2015 University of Texas at Austin news release, which originated the news item, provides more details about the research which has spawned two recently published papers,

The team now has engineered two new advancements in electrochromic materials — a highly selective cool mode and a warm mode — not thought possible several years ago.

The cool mode material is a major step toward a commercialized product because it enables control of 90 percent of NIR and 80 percent of the visible light from the sun and takes only minutes to switch between modes. The previously reported material could require hours.

To achieve this high performance, Milliron and a team, including Cockrell School postdoctoral researcher Jongwook Kim and collaborator Brett Helms of the Lawrence Berkeley National Lab, developed a new nanostructured architecture for electrochromic materials that allows for a cool mode to block near-infrared light while allowing the visible light to shine through. This could help reduce energy costs for cooling buildings and homes during the summer. The researchers reported the new architecture in Nano Letters on July 20.

“We believe our new architected nanocomposite could be seen as a model material, establishing the ideal design for a dual-band electrochromic material,” Milliron said. “This material could be ideal for application as a smart electrochromic window for buildings.”

In the paper, the team demonstrates how the new material can strongly and selectively modulate visible light and NIR by applying a small voltage.

To optimize the performance of electrochromics for practical use, the team organized the two components of the composite material to create a porous interpenetrating network. The framework architecture provides channels for transport of electronic and ionic change. This organization enables substantially faster switching between modes.
Smart Window

The researchers are now working to produce a similarly structured nanocomposite material by simple methods, suitable for low-cost manufacturing.

In a second research paper, Milliron and her team, including Cockrell School graduate student Clayton Dahlman, have reported a proof-of-concept demonstrating how they can achieve optical control properties in windows from a well-crafted, single-component film. The concept includes a simple coating that creates a new warm mode, in which visible light can be blocked, while near-infrared light can enter. This new setting could be most useful on a sunny winter day, when an occupant would want infrared radiation to pass into a building for warmth, but the glare from sunlight to be reduced.

In this paper, published in the Journal of the American Chemical Society, Milliron proved that a coating containing a single component ­— doped titania nanocrystals — could demonstrate dynamic control over the transmittance of solar radiation. Because of two distinct charging mechanisms found at different applied voltages, this material can selectively block visible or infrared radiation.

“These two advancements show that sophisticated dynamic control of sunlight is possible,” Milliron said. “We believe our deliberately crafted nanocrystal-based materials could meet the performance and cost targets needed to progress toward commercialization of smart windows.”

Interestingly, the news release includes this statement,

The University of Texas at Austin is committed to transparency and disclosure of all potential conflicts of interest. The lead UT investigator involved with this project, Delia Milliron, is the chief scientific officer and owns an equity position in Heliotrope Technologies, an early-stage company developing new materials and manufacturing processes for electrochromic devices with an emphasis on energy-saving smart windows. Milliron is associated with patents at Lawrence Berkeley National Laboratory licensed to Heliotrope Technologies. Collaborator Brett Helms serves on the scientific advisory board of Heliotrope and owns equity in the company.

Here are links to and citations for the two papers,

Nanocomposite Architecture for Rapid, Spectrally-Selective Electrochromic Modulation of Solar Transmittance by Jongwook Kim, Gary K. Ong, Yang Wang, Gabriel LeBlanc, Teresa E. Williams, Tracy M. Mattox, Brett A. Helms, and Delia J. Milliron. Nano Lett., Article ASAP DOI: 10.1021/acs.nanolett.5b02197 Publication Date (Web): July 20, 2015

Copyright © 2015 American Chemical Society

Spectroelectrochemical Signatures of Capacitive Charging and Ion Insertion in Doped Anatase Titania Nanocrystals by Clayton J. Dahlman, Yizheng Tan, Matthew A. Marcus, and Delia J. Milliron. J. Am. Chem. Soc., 2015, 137 (28), pp 9160–9166 DOI: 10.1021/jacs.5b04933 Publication Date (Web): July 8, 2015

Copyright © 2015 American Chemical Society

These papers are behind paywalls.

University of Toronto researchers combine 2 different materials for new hyper-efficient, light-emitting, hybrid crystal

The Sargent Group at the University of Toronto has been quite active with regard to LEDs (light-emitting diodes) and with quantum dots. Their latest work is announced in a July 16, 2015 news item on Nanotechnology Now (Note: I had to include the ‘oatmeal cookie and chocolate chips’ analogy in the first paragraph as it’s referred to subsequently),

It’s snack time: you have a plain oatmeal cookie, and a pile of chocolate chips. Both are delicious on their own, but if you can find a way to combine them smoothly, you get the best of both worlds.

Researchers in The Edward S. Rogers Sr. Department of Electrical & Computer Engineering [University of Toronto] used this insight to invent something totally new: they’ve combined two promising solar cell materials together for the first time, creating a new platform for LED technology.

The team designed a way to embed strongly luminescent nanoparticles called colloidal quantum dots (the chocolate chips) into perovskite (the oatmeal cookie). Perovskites are a family of materials that can be easily manufactured from solution, and that allow electrons to move swiftly through them with minimal loss or capture by defects.

A July 15, 2015 University of Toronto news release (also on EurekAlert), which originated the news item, reveals more about the research (Note: A link has been removed),

“It’s a pretty novel idea to blend together these two optoelectronic materials, both of which are gaining a lot of traction,” says Xiwen Gong, one of the study’s lead authors and a PhD candidate working with Professor Ted Sargent. “We wanted to take advantage of the benefits of both by combining them seamlessly in a solid-state matrix.”

The result is a black crystal that relies on the perovskite matrix to ‘funnel’ electrons into the quantum dots, which are extremely efficient at converting electricity to light. Hyper-efficient LED technologies could enable applications from the visible-light LED bulbs in every home, to new displays, to gesture recognition using near-infrared wavelengths.

“When you try to jam two different crystals together, they often form separate phases without blending smoothly into each other,” says Dr. Riccardo Comin, a post-doctoral fellow in the Sargent Group. “We had to design a new strategy to convince these two components to forget about their differences and to rather intermix into forming a unique crystalline entity.”

The main challenge was making the orientation of the two crystal structures line up, called heteroexpitaxy. To achieve heteroepitaxy, Gong, Comin and their team engineered a way to connect the atomic ‘ends’ of the two crystalline structures so that they aligned smoothly, without defects forming at the seams. “We started by building a nano-scale scaffolding ‘shell’ around the quantum dots in solution, then grew the perovskite crystal around that shell so the two faces aligned,” explained coauthor Dr. Zhijun Ning, who contributed to the work while a post-doctoral fellow at UofT and is now a faculty member at ShanghaiTech.

The resulting heterogeneous material is the basis for a new family of highly energy-efficient near-infrared LEDs. Infrared LEDs can be harnessed for improved night-vision technology, to better biomedical imaging, to high-speed telecommunications.

Combining the two materials in this way also solves the problem of self-absorption, which occurs when a substance partly re-absorbs the same spectrum of energy that it emits, with a net efficiency loss. “These dots in perovskite don’t suffer reabsorption, because the emission of the dots doesn’t overlap with the absorption spectrum of the perovskite,” explains Comin.

Gong, Comin and the team deliberately designed their material to be compatible with solution-processing, so it could be readily integrated with the most inexpensive and commercially practical ways of manufacturing solar film and devices. Their next step is to build and test the hardware to capitalize on the concept they have proven with this work.

“We’re going to build the LED device and try to beat the record power efficiency reported in the literature,” says Gong.

I see that Sargent’s work is still associated with and supported by Saudi Arabia, from the news release,

This work was supported by the Ontario Research Fund Research Excellence Program, the Natural Sciences and Engineering Research Council of Canada (NSERC), and the King Abdullah University of Science & Technology (KAUST).

Here’s a link to and a citation for the paper,

Quantum-dot-in-perovskite solids by Zhijun Ning, Xiwen Gong, Riccardo Comin, Grant Walters, Fengjia Fan, Oleksandr Voznyy, Emre Yassitepe, Andrei Buin, Sjoerd Hoogland, & Edward H. Sargent. Nature 523, 324–328 (16 July 2015) doi:10.1038/nature14563 Published online 15 July 2015

This paper is behind a paywall.

Finally, the researchers have made a .gif of their hybrid crystal available.

A glowing quantum dot seamlessly integrated into a perovskite crystal matrix (Image: Ella Marushchenko). Courtesy: University of Toronto

A glowing quantum dot seamlessly integrated into a perovskite crystal matrix (Image: Ella Marushchenko). Courtesy: University of Toronto

ETA July 17, 2015:

Dexter Johnson provides some additional insight into the work in his July 16, 2015 posting on the Nanoclast blog (on the Institute for Electrical and Electronics Engineers website), Note:  Links have been removed,

Ted Sargent at the University of Toronto has built a reputation over the years as being a prominent advocate for the use of quantum dots in photovoltaics. Sargent has even penned a piece for IEEE Spectrum covering the topic, and this blog has covered his record breaking efforts at boosting the conversion efficiency of quantum dot-based photovoltaics a few times.

Earlier this year, however, Sargent started to take an interest in the hot material that has the photovoltaics community buzzing: perovskite. …

Extending catalyst life for oil and gas

A July 6, 2015 news item on Nanowerk describes the progress on determining exactly how catalysis is achieved when using zeolite (Note: A link has been removed),

Despite decades of industrial use, the exact chemical transformations occurring within zeolites, a common material used in the conversion of oil to gasoline, remain poorly understood. Now scientists have found a way to locate—with atomic precision—spots within the material where chemical reactions take place, and how these spots shut down.

Called active sites, the spots help rip apart and rearrange molecules as they pass through nanometer-sized channels, like an assembly line in a factory. A process called steaming causes these active sites to cluster, effectively shutting down the factory, the scientists reported in Nature Communications (“Determining the location and nearest neighbours of aluminium in zeolites with atom probe tomography”). This knowledge could help devise how to keep the factory running longer, so to speak, and improve catalysts that help produce fuel, biofuel and other chemicals.

A July 6, 2015 Pacific Northwest National Laboratories (PNNL) news release (also on EurekAlert), which originated the news item, describes the collaboration and the research in more detail (Note: Links have been removed),

The team included scientists from the Department of Energy’s Pacific Northwest National Laboratory, petroleum refining technology company UOP LLC and Utrecht University. To make this discovery, they reconstructed the first 3-D atomic map of an industrially relevant zeolite material to track down its key element, aluminum.

When things get steamy, structure changes

Zeolites are minerals made up of aluminum, silicon and oxygen atoms arranged in a three-dimensional crystalline structure. Though they look like white powder to the naked eye, zeolites have a sponge-like network of molecule-size pores. Aluminum atoms along these pores act like workers on an assembly line-they create active sites that give zeolites their catalytic properties.

Industry uses about a dozen synthetic zeolites as catalysts to process petroleum and chemicals. One major conversion process, called fluid catalytic cracking, depends on zeolites to produce the majority of the world’s gasoline. [emphasis mine]

To awaken active sites within zeolites, industry pretreats the material with heat and water, a process called steaming. But too much steaming somehow switches the sites off. Changing the conditions of steaming could extend the catalyst’s life, thus producing fuel more efficiently.

Scientists have long suspected that steaming causes aluminum to move around within the material, thus changing its properties. But until now aluminum has evaded detailed analysis.

Strip away the atoms

Most studies of zeolite structure rely on electron microscopy, which can’t easily distinguish aluminum from silicon because of their similar masses. Worse, the instrument’s intense electron beam tends to damage the material, changing its inherent structure before it’s seen.

Instead, the team of scientists turned to a characterization technique that had never before been successfully applied to zeolites. Called atom probe tomography, it works by zapping a sample with a pulsing laser, providing just enough energy to knock off one atom at a time. Time-of-flight mass spectrometers analyze each atom-at a rate of about 1,000 atoms per second. Unlike an electron microscope, this technique can distinguish aluminum from silicon.

Though atom probe tomography has been around for 50 years, it was originally designed to look at conductive materials, such as metals. Less conductive zeolites presented a problem.

PNNL materials scientist Danny Perea and his colleagues overcame this hurdle by adapting a Local Electrode Atom Probe at EMSL, the Environmental Molecular Sciences Laboratory, a DOE Office of Science User Facility accessible to scientists around the world. Most attempts to image the material ended prematurely, when electromagnetic forces within the instrument vaporized the entire sample. The key to success was to find the right conditions to prepare a sample and then to coat it with a layer of metal to help provide conductivity and strength to withstand analysis.

After hours of blasting tens-of-millions of atoms, the scientists could reconstruct an atomic map of a sample about a thousand times smaller than the width of a human hair. These maps hold clues as to why the catalyst fails.

The news release reveals what the scientists were able to see for the first time,

The images confirmed what scientists have long suspected: Steaming causes aluminum atoms to cluster. Like workers crowded around one spot on the assembly line, this clustering effectively shuts down the catalytic factory.

The scientists even pinpointed the place where aluminum likes to cluster. Zeolite crystals often grow in overlapping sub-units, forming something like a 3-D Venn diagram. Scientists call the edge between two sub-units a grain boundary, and that’s where the aluminum clustered. The scientists suspect that open space along grain boundaries attracted the aluminum.

With the guidance of these atomic maps, industry could one day modify how it steams zeolites to produce a more efficient, longer lasting catalyst. The research team will next examine other industrially important zeolites at different stages of steaming to provide a more detailed map of this transformation.

Here’s a link to and a citation for the paper,

Determining the location and nearest neighbours of aluminium in zeolites with atom probe tomography by Daniel E. Perea, Ilke Arslan, Jia Liu, Zoran Ristanović, Libor Kovarik, Bruce W. Arey, Johannes A. Lercher, Simon R. Bare, & Bert M. Weckhuysen.  Nature Communications 6, Article number: 7589 doi:10.1038/ncomms8589 Published 02 July 2015

This is an open access paper.

Your tires generate energy that can be harvested

One day, this new work from the University of Wisconsin-Madison could help cut gas expenditures for your car and other motorized vehicles dependent on fossil fuels. A June 29, 2015 news item on Nanowerk describes the research (Note: A link has been removed),

A group of University of Wisconsin-Madison engineers and a collaborator from China have developed a nanogenerator that harvests energy from a car’s rolling tire friction.

An innovative method of reusing energy, the nanogenerator ultimately could provide automobile manufacturers a new way to squeeze greater efficiency out of their vehicles.

The researchers reported their development, which is the first of its kind, in a paper published May 6, 2015, in the journal Nano Energy (“Single-electrode triboelectric nanogenerator for scavenging friction energy from rolling tires”).

A June 29, 2015 University of Wisconsin-Madison news release (also on EurekAlert), which originated the news item, provides more details (Note: Links have been removed),

Xudong Wang, the Harvey D. Spangler fellow and an associate professor of materials science and engineering at UW-Madison, and his PhD student Yanchao Mao have been working on this device for about a year.

The nanogenerator relies on the triboelectric effect to harness energy from the changing electric potential between the pavement and a vehicle’s wheels. The triboelectric effect is the electric charge that results from the contact or rubbing together of two dissimilar objects.

Wang says the nanogenerator provides an excellent way to take advantage of energy that is usually lost due to friction.

“The friction between the tire and the ground consumes about 10 percent of a vehicle’s fuel,” he says. “That energy is wasted. So if we can convert that energy, it could give us very good improvement in fuel efficiency.”

The nanogenerator relies on an electrode integrated into a segment of the tire. When this part of the tire surface comes into contact with the ground, the friction between those two surfaces ultimately produces an electrical charge-a type of contact electrification known as the triboelectric effect.

During initial trials, Wang and his colleagues used a toy car with LED lights to demonstrate the concept. They attached an electrode to the wheels of the car, and as it rolled across the ground, the LED lights flashed on and off. The movement of electrons caused by friction was able to generate enough energy to power the lights, supporting the idea that energy lost to friction can actually be collected and reused.

“Regardless of the energy being wasted, we can reclaim it, and this makes things more efficient,” Wang says. “I think that’s the most exciting part of this, and is something I’m always looking for: how to save the energy from consumption.”

The researchers also determined that the amount of energy harnessed is directly related to the weight of a car, as well as its speed. Therefore the amount of energy saved can vary depending on the vehicle-but Wang estimates about a 10-percent increase in the average vehicle’s gas mileage given 50-percent friction energy conversion efficiency.

“There’s big potential with this type of energy,” Wang says. “I think the impact could be huge.”

Here’s a link to and a citation for the paper,

Single-electrode triboelectric nanogenerator for scavenging friction energy from rolling tires by Yanchao Mao, Dalong Geng, Erjun Liang, & Xudong Wang. Nano Energy Volume 15, July 2015, Pages 227–234 doi:10.1016/j.nanoen.2015.04.026

This paper is behind a paywall.

LEDs (light-emitting diodes) that need less energy and give better light

A June 24, 2015 University of Copenhagen Niels Bohr Institute press release (also on EurekAlert), announces research that could lead to a brighter future (pun intended),

The researchers [from the Niels Bohr Institute] studied nanowires using X-ray microscopy and with this method they can pinpoint exactly how the nanowire should be designed to give the best properties. …

Nanowires are very small – about 2 micrometers high (1 micrometer is a thousandth of a millimetre) and 10-500 nanometers in diameter (1 nanometer is a thousandth of a micrometer). Nanowires for LEDs are made up of an inner core of gallium nitride (GaN) and a layer of indium-gallium-nitride (InGaN) on the outside, both of which are semiconducting materials.

“The light in such a diode is dependent on the mechanical strain that exists between the two materials and the strain is very dependent on how the two layers are in contact with each other. We have examined a number of nanowires using X-ray microscopy and even though the nanowires should in principle be identical, we can see that they are different and have very different structure,” explains Robert Feidenhans’l, professor and head of the Niels Bohr Institute at the University of Copenhagen.

Surprisingly efficient

The studies were performed using nanoscale X-ray microscopy in the electron synchrotron at DESY in Hamburg, Germany. The method is usually very time consuming and the results are often limited to very few or even a single study subject. But here researchers have managed to measure a series of upright nanowires all at once using a special design of a nanofocused X-ray without destroying the nanowires in the process.

“We measured 20 nanowires and when we saw the images, we were very surprised because you could clearly see the details of each nanowire. You can see the structure of both the inner core and the outer layer. If there are defects in the structure or if they are slightly bent, they do not function as well. So we can identify exactly which nanowires are the best and have the most efficient core/shell structure,” explains Tomas Stankevic, a PhD student in the research group ‘Neutron and X-ray Scattering’ at the Niels Bohr Institute at the University of Copenhagen.

The nanowires are produced by a company in Sweden and this new information can be used to tweak the layer structure in the nanowires. Professor Robert Feidenhans’l explains that there is great potential in such nanowires. They will provide a more natural light in LEDs and they will use much less power. In addition, they could be used in smart phones, televisions and many forms of lighting.

The researchers expect that things could go very quickly and that they may already be in use within five years.

Here’s a link to and a citation for the paper,

Fast Strain Mapping of Nanowire Light-Emitting Diodes Using Nanofocused X-ray Beams by Tomaš Stankevič, Emelie Hilner, Frank Seiboth, Rafal Ciechonski, Giuliano Vescovi, Olga Kryliouk, Ulf Johansson, Lars Samuelson, Gerd Wellenreuther, Gerald Falkenberg, Robert Feidenhans’l, and Anders Mikkelsen.
ACS Nano, Article ASAP DOI: 10.1021/acsnano.5b01291
Publication Date (Web): June 19, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Solar-powered sensors to power the Internet of Things?

As a June 23, 2015 news item on Nanowerk notes, the ‘nternet of things’, will need lots and lots of power,

The latest buzz in the information technology industry regards “the Internet of things” — the idea that vehicles, appliances, civil-engineering structures, manufacturing equipment, and even livestock would have their own embedded sensors that report information directly to networked servers, aiding with maintenance and the coordination of tasks.

Realizing that vision, however, will require extremely low-power sensors that can run for months without battery changes — or, even better, that can extract energy from the environment to recharge.

Last week, at the Symposia on VLSI Technology and Circuits, MIT [Massachusetts Institute of Technology] researchers presented a new power converter chip that can harvest more than 80 percent of the energy trickling into it, even at the extremely low power levels characteristic of tiny solar cells. [emphasis mine] Previous experimental ultralow-power converters had efficiencies of only 40 or 50 percent.

A June 22, 2015 MIT news release (also on EurekAlert), which originated the news item, describes some additional capabilities,

Moreover, the researchers’ chip achieves those efficiency improvements while assuming additional responsibilities. Where its predecessors could use a solar cell to either charge a battery or directly power a device, this new chip can do both, and it can power the device directly from the battery.

All of those operations also share a single inductor — the chip’s main electrical component — which saves on circuit board space but increases the circuit complexity even further. Nonetheless, the chip’s power consumption remains low.

“We still want to have battery-charging capability, and we still want to provide a regulated output voltage,” says Dina Reda El-Damak, an MIT graduate student in electrical engineering and computer science and first author on the new paper. “We need to regulate the input to extract the maximum power, and we really want to do all these tasks with inductor sharing and see which operational mode is the best. And we want to do it without compromising the performance, at very limited input power levels — 10 nanowatts to 1 microwatt — for the Internet of things.”

The prototype chip was manufactured through the Taiwan Semiconductor Manufacturing Company’s University Shuttle Program.

The MIT news release goes on to describe chip specifics,

The circuit’s chief function is to regulate the voltages between the solar cell, the battery, and the device the cell is powering. If the battery operates for too long at a voltage that’s either too high or too low, for instance, its chemical reactants break down, and it loses the ability to hold a charge.

To control the current flow across their chip, El-Damak and her advisor, Anantha Chandrakasan, the Joseph F. and Nancy P. Keithley Professor in Electrical Engineering, use an inductor, which is a wire wound into a coil. When a current passes through an inductor, it generates a magnetic field, which in turn resists any change in the current.

Throwing switches in the inductor’s path causes it to alternately charge and discharge, so that the current flowing through it continuously ramps up and then drops back down to zero. Keeping a lid on the current improves the circuit’s efficiency, since the rate at which it dissipates energy as heat is proportional to the square of the current.

Once the current drops to zero, however, the switches in the inductor’s path need to be thrown immediately; otherwise, current could begin to flow through the circuit in the wrong direction, which would drastically diminish its efficiency. The complication is that the rate at which the current rises and falls depends on the voltage generated by the solar cell, which is highly variable. So the timing of the switch throws has to vary, too.

Electric hourglass

To control the switches’ timing, El-Damak and Chandrakasan use an electrical component called a capacitor, which can store electrical charge. The higher the current, the more rapidly the capacitor fills. When it’s full, the circuit stops charging the inductor.

The rate at which the current drops off, however, depends on the output voltage, whose regulation is the very purpose of the chip. Since that voltage is fixed, the variation in timing has to come from variation in capacitance. El-Damak and Chandrakasan thus equip their chip with a bank of capacitors of different sizes. As the current drops, it charges a subset of those capacitors, whose selection is determined by the solar cell’s voltage. Once again, when the capacitor fills, the switches in the inductor’s path are flipped.

“In this technology space, there’s usually a trend to lower efficiency as the power gets lower, because there’s a fixed amount of energy that’s consumed by doing the work,” says Brett Miwa, who leads a power conversion development project as a fellow at the chip manufacturer Maxim Integrated. “If you’re only coming in with a small amount, it’s hard to get most of it out, because you lose more as a percentage. [El-Damak’s] design is unusually efficient for how low a power level she’s at.”

“One of the things that’s most notable about it is that it’s really a fairly complete system,” he adds. “It’s really kind of a full system-on-a chip for power management. And that makes it a little more complicated, a little bit larger, and a little bit more comprehensive than some of the other designs that might be reported in the literature. So for her to still achieve these high-performance specs in a much more sophisticated system is also noteworthy.”

I wonder how close they are to commercializing this chip (see below),

The MIT researchers' prototype for a chip measuring 3 millimeters by 3 millimeters. The magnified detail shows the chip's main control circuitry, including the startup electronics; the controller that determines whether to charge the battery, power a device, or both; and the array of switches that control current flow to an external inductor coil. This active area measures just 2.2 millimeters by 1.1 millimeters. (click on image to enlarge) Read more: Toward tiny, solar-powered sensors. Courtesy: MIT

The MIT researchers’ prototype for a chip measuring 3 millimeters by 3 millimeters. The magnified detail shows the chip’s main control circuitry, including the startup electronics; the controller that determines whether to charge the battery, power a device, or both; and the array of switches that control current flow to an external inductor coil. This active area measures just 2.2 millimeters by 1.1 millimeters. (click on image to enlarge)
Courtesy: MIT

Saharan silver ants: the nano of it all (science and technology)

Researchers at Columbia University (US) are on quite a publishing binge lately. The latest is a biomimicry story where researchers (from Columbia amongst other universities and including Brookhaven National Laboratory, which has issued its own news release) have taken a very close look at Saharan silver ants to determine how they stay cool in one of the hottest climates in the world. From a June 18, 2015 Columbia University news release (also on EurekAlert), Note: Links have been removed,

Nanfang Yu, assistant professor of applied physics at Columbia Engineering, and colleagues from the University of Zürich and the University of Washington, have discovered two key strategies that enable Saharan silver ants to stay cool in one of the hottest terrestrial environments on Earth. Yu’s team is the first to demonstrate that the ants use a coat of uniquely shaped hairs to control electromagnetic waves over an extremely broad range from the solar spectrum (visible and near-infrared) to the thermal radiation spectrum (mid-infrared), and that different physical mechanisms are used in different spectral bands to realize the same biological function of reducing body temperature. Their research, “Saharan silver ants keep cool by combining enhanced optical reflection and radiative heat dissipation,” is published June 18 [2015] in Science magazine.

The Columbia University news release expands on the theme,

“This is a telling example of how evolution has triggered the adaptation of physical attributes to accomplish a physiological task and ensure survival, in this case to prevent Saharan silver ants from getting overheated,” Yu says. “While there have been many studies of the physical optics of living systems in the ultraviolet and visible range of the spectrum, our understanding of the role of infrared light in their lives is much less advanced. Our study shows that light invisible to the human eye does not necessarily mean that it does not play a crucial role for living organisms.”

The project was initially triggered by wondering whether the ants’ conspicuous silvery coats were important in keeping them cool in blistering heat. Yu’s team found that the answer to this question was much broader once they realized the important role of infrared light. Their discovery that there is a biological solution to a thermoregulatory problem could lead to the development of novel flat optical components that exhibit optimal cooling properties.

“Such biologically inspired cooling surfaces will have high reflectivity in the solar spectrum and high radiative efficiency in the thermal radiation spectrum,” Yu explains. “So this may generate useful applications such as a cooling surface for vehicles, buildings, instruments, and even clothing.”

Saharan silver ants (Cataglyphis bombycina) forage in the Saharan Desert in the full midday sun when surface temperatures reach up to 70°C (158°F), and they must keep their body temperature below their critical thermal maximum of 53.6°C (128.48°F) most of the time. In their wide-ranging foraging journeys, the ants search for corpses of insects and other arthropods that have succumbed to the thermally harsh desert conditions, which they are able to endure more successfully. Being most active during the hottest moment of the day also allows these ants to avoid predatory desert lizards. Researchers have long wondered how these tiny insects (about 10 mm, or 3/8” long) can survive under such thermally extreme and stressful conditions.

Using electron microscopy and ion beam milling, Yu’s group discovered that the ants are covered on the top and sides of their bodies with a coating of uniquely shaped hairs with triangular cross-sections that keep them cool in two ways. These hairs are highly reflective under the visible and near-infrared light, i.e., in the region of maximal solar radiation (the ants run at a speed of up to 0.7 meters per second and look like droplets of mercury on the desert surface). The hairs are also highly emissive in the mid-infrared portion of the electromagnetic spectrum, where they serve as an antireflection layer that enhances the ants’ ability to offload excess heat via thermal radiation, which is emitted from the hot body of the ants to the cold sky. This passive cooling effect works under the full sun whenever the insects are exposed to the clear sky.

“To appreciate the effect of thermal radiation, think of the chilly feeling when you get out of bed in the morning,” says Yu. “Half of the energy loss at that moment is due to thermal radiation since your skin temperature is temporarily much higher than that of the surrounding environment.”

The researchers found that the enhanced reflectivity in the solar spectrum and enhanced thermal radiative efficiency have comparable contributions to reducing the body temperature of silver ants by 5 to 10 degrees compared to if the ants were without the hair cover. “The fact that these silver ants can manipulate electromagnetic waves over such a broad range of spectrum shows us just how complex the function of these seemingly simple biological organs of an insect can be,” observes Norman Nan Shi, lead author of the study and PhD student who works with Yu at Columbia Engineering.

Yu and Shi collaborated on the project with Rüdiger Wehner, professor at the Brain Research Institute, University of Zürich, Switzerland, and Gary Bernard, electrical engineering professor at the University of Washington, Seattle, who are renowned experts in the study of insect physiology and ecology. The Columbia Engineering team designed and conducted all experimental work, including optical and infrared microscopy and spectroscopy experiments, thermodynamic experiments, and computer simulation and modeling. They are currently working on adapting the engineering lessons learned from the study of Saharan silver ants to create flat optical components, or “metasurfaces,” that consist of a planar array of nanophotonic elements and provide designer optical and thermal radiative properties.

Yu and his team plan next to extend their research to other animals and organisms living in extreme environments, trying to learn the strategies these creatures have developed to cope with harsh environmental conditions.

“Animals have evolved diverse strategies to perceive and utilize electromagnetic waves: deep sea fish have eyes that enable them to maneuver and prey in dark waters, butterflies create colors from nanostructures in their wings, honey bees can see and respond to ultraviolet signals, and fireflies use flash communication systems,” Yu adds. “Organs evolved for perceiving or controlling electromagnetic waves often surpass analogous man-made devices in both sophistication and efficiency. Understanding and harnessing natural design concepts deepens our knowledge of complex biological systems and inspires ideas for creating novel technologies.”

Next, there’s the perspective provided by Brookhaven National Laboratory in a June 18, 2015 news item on Nanowerk (Note: It is very similar to the Columbia University news release but it takes a turn towards the technical challenges as you’ll see if you keep reading),

The paper, published by Columbia Engineering researchers and collaborators—including researchers from the U.S. Department of Energy’s (DOE) Brookhaven National Laboratory—describes how the nanoscale structure of the hairs helps increase the reflectivity of the ant’s body in both visible and near-infrared wavelengths, allowing the insects to deflect solar radiation their bodies would otherwise absorb. The hairs also enhance emissivity in the mid-infrared spectrum, allowing heat to dissipate efficiently from the hot body of the ants to the cool, clear sky.

A June 18, 2015 BNL news release by Alasdair Wilkins, which originated the Nanowerk news item, describes the collaboration between the researchers and the special adjustments made to the equipment in service of this project (Note: A link has been removed),

In a typical experiment involving biological material such as nanoscale hairs, it would usually be sufficient to use an electron microscope to create an image of the surface of the specimen. This research, however, required Yu’s group to look inside the ant hairs and produce a cross-section of the structure’s interior. The relatively weak beam of electrons from a standard electron microscope would not be able to penetrate the surface of the sample.

The CFN’s dual beam system solves the problem by combining the imaging of an electron microscope with a much more powerful beam of gallium ions.  With 31 protons and 38 neutrons, each gallium ion is about 125,000 times more massive than an electron, and massive enough to create dents in the nanoscale structure – like throwing a stone against a wall. The researchers used these powerful beams to drill precise cuts into the hairs, revealing the crucial information hidden beneath the surface. Indeed, this particular application, in which the system was used to investigate a biological problem, was new for the team at CFN.

“Conventionally, this tool is used to produce cross-sections of microelectronic circuits,” said Camino. “The focused ion beam is like an etching tool. You can think of it like a milling tool in a machine shop, but at the nanoscale. It can remove material at specific places because you can see these locations with the SEM. So locally you remove material and you look at the under layers, because the cuts give you access to the cross section of whatever you want to look at.”

The ant hair research challenged the CFN team to come up with novel solutions to investigate the internal structures without damaging the more delicate biological samples.

“These hairs are very soft compared to, say, semiconductors or crystalline materials. And there’s a lot of local heat that can damage biological samples. So the parameters have to be carefully tuned not to do much damage to it,” he said. “We had to adapt our technique to find the right conditions.”

Another challenge lay in dealing with the so-called charging effect. When the dual beam system is trained on a non-conducting material, electrons can build up at the point where the beams hit the specimen, distorting the resulting image. The team at CFN was able to solve this problem by placing thin layers of gold over the biological material, making the sample just conductive enough to avoid the charging effect.

Revealing Reflectivity

While Camino’s team focused on helping Yu’s group investigate the structure of the ant hairs, Matthew Sfeir’s work with high-brightness Fourier transform optical spectroscopy helped to reveal how the reflectivity of the hairs helped Saharan silver ants regulate temperature. Sfeir’s spectrometer revealed precisely how much those biological structures reflect light across multiple wavelengths, including both visible and near-infrared light.

“It’s a multiplexed measurement,” Sfeir said, explaining his team’s spectrometer. “Instead of tuning through this wavelength and this wavelength, that wavelength, you do them all in one swoop to get all the spectral information in one shot. It gives you very fast measurements and very good resolution spectrally. Then we optimize it for very small samples. It’s a rather unique capability of CFN.”

Sfeir’s spectroscopy work draws on knowledge gained from his work at another key Brookhaven facility: the original National Synchrotron Light Source, where he did much of his postdoc work. His experience was particularly useful in analyzing the reflectivity of the biological structures across many different wavelengths of the electromagnetic spectrum.

“This technique was developed from my experience working with the infrared synchrotron beamlines,” said Sfeir. “Synchrotron beamlines are optimized for exactly this kind of thing. I thought, ‘Hey, wouldn’t it be great if we could develop a similar measurement for the type of solar devices we make at CFN?’ So we built a bench-top version to use here.”

Fascinating, non? At last, here’s a link to and a citation for the paper,

Keeping cool: Enhanced optical reflection and heat dissipation in silver ants by Norman Nan Shi, Cheng-Chia Tsai, Fernando Camino, Gary D. Bernard, Nanfang Yu, and Rüdiger Wehner. Science DOI: 10.1126/science.aab3564 Published online June 18, 2015

This paper is behind a paywall.

Platinum catalysts and their shortcomings

The problem boils down to the fact that platinum isn’t cheap and so US Dept. of Energy research laboratories are looking for alternatives to or ways of making more efficient use of platinum according to a June 16, 2015 news item on Nanowerk,

Visions of dazzling engagement rings may pop to mind when platinum is mentioned, but a significant share of the nearly half a million pounds of the rare metalExternal link [sic] mined each year ends up in vehicle emission systems and chemical manufacturing plants. The silvery white metal speeds up or enhances reactions, a role scientists call serving as a catalyst, and platinum is fast and efficient performing this function.

Because of its outstanding performance as a catalyst, platinum plays a major role in fuel cells. Inside a fuel cell, tiny platinum particles break apart hydrogen fuel to create electricity. Leftover protons are combined with oxygen ions to create pure water.

Fuel cells could let scientists turn wind into fuel. Right now, electricity generated by wind turbines is not stored. If that energy could be converted into hydrogen to power fuel cells, it would turn a sporadic source into a continuous one.

The problem is the platinum – a scarce and costly metal. Scientists funded by the U.S. Department of Energy’s Office of Science are seeing if something more readily available, such as iron or nickel, could catalyze the reaction.

But, earth-abundant metals cannot simply be used in place of platinum and other rare metals. Each metal works differently at the atomic level. It takes basic research to understand the interactions and use that knowledge to create the right catalysts.

A June 15, 2015 US Department of Energy Office of Science news release, which originated the news item, describes various efforts,

At the Center for Molecular Electrocatalysis, an Energy Frontier Research Center, scientists are gaining new understanding of catalysts based on common metals and how they move protons, the positively charged, oft-ignored counterpart to the electron.

Center Director Morris Bullock and his colleagues showed that protons’ ability to move through the catalyst greatly influences the catalyst’s speed and efficiency. Protons move via relays — clusters of atoms that convey protons to or from the active site of catalysts, where the reaction of interest occurs. The constitution, placement, and number of relays can let a reaction zip along or grind to a halt. Bullock and his colleagues are creating “design guidelines” for building relays.

Further, the team is expanding the guidelines to examine proton movement related to the solutions and surfaces where the catalyst resides. For example, matching the proton-donating abilityExternal link [sic] of a nickel-based catalyst to that of the surrounding liquid, much like matching your clothing choice with the event you’re attending, eases protons’ travels. The benefit? Speed. A coordinated catalyst pumped out 96,000 hydrogen molecules a second — compared to just 27,000 molecules a second without the adjustment.

This and other research at the Energy Frontier Research Center is funded by the DOE Office of Science’s Office of Basic Energy Sciences. The Center is led by Pacific Northwest National Laboratory.

At two other labs, research shows how changing the catalyst’s superstructure, which contains the proton relays and wraps around the active site, can also increase the speed of the reaction. Led by Argonne National Lab’s Vojislav Stamenkovic and Berkeley Lab’s Peidong Yang, researchers created hollow platinum and nickel nanoparticles, a thousand times smaller in diameter than a human hair. The 12-sided particles split oxygen molecules into charged oxygen ions, a reaction that’s needed in fuel cells. The new catalyst is far more active and uses far less platinum than conventional platinum-carbon catalysts.

Building the catalysts begins with tiny structures made of platinum and nickel held in solution. Oxygen from the air dissolves into the liquid and selectively etches away some of the nickel atoms. The result is a hollow framework with a highly active platinum skin over the surface. The open design of the catalyst allows the oxygen to easily access the platinum. The new catalyst has a 36-fold increase in activity compared to traditional platinum–carbon catalysts. Further, the new hollow structure continues to work far longer in operating fuel cells than traditional catalysts.

I think we’re entering the ‘slow’ season newswise so there are likely to be more of these ’roundup’ pieces being circulated in the online nanosciencesphere and, consequently, here. too.

Construction and nanotechnology research in Scandinavia

I keep hearing about the possibilities for better (less polluting, more energy efficient, etc.) building construction materials but there never seems to be much progress.  A June 15, 2015 news item on Nanowerk, which suggests some serious efforts are being made in Scandinavia, may help to explain the delay,

It isn’t cars and vehicle traffic that produce the greatest volumes of climate gas emissions – it’s our own homes. But new research will soon be putting an end to all that!

The building sector is currently responsible for 40% of global energy use and climate gas emissions. This is an under-communicated fact in a world where vehicle traffic and exhaust emissions get far more attention.

In the future, however, we will start to see construction materials and high-tech systems integrated into building shells that are specifically designed to remedy this situation. Such systems will be intelligent and multifunctional. They will consume less energy and generate lower levels of harmful climate gas emissions.

With this objective in mind, researchers at SINTEF are currently testing microscopic nanoparticles as insulation materials, applying voltages to window glass and facades as a means of saving energy, and developing solar cells that prevent the accumulation of snow and ice.

Research Director Susie Jahren and Research Manager Petra Rüther are heading SINTEF’s strategic efforts in the field of future construction materials. They say that although there are major commercial opportunities available in the development of green and low carbon building technologies, the construction industry is somewhat bound by tradition and unable to pay for research into future technology development. [emphasis mine]

A June 15, 2015 SINTEF (Scandinavia’s largest independent research organisation) news release on the Alpha Galileo website, which originated the news item, provides an overview of the research being conducted into nanotechnology-enabled construction materials (Note: I have added some heads and ruthlessly trimmed from the text),

[Insulation]

SINTEF researcher Bente Gilbu Tilset is sitting in her office in Forskningsveien 1 in Oslo [Norway]. She and her colleagues are looking into the manufacture of super-insulation materials made up of microscopic nanospheres.

“Our aim is to create a low thermal conductivity construction material “, says Tilset. “When gas molecules collide, energy is transferred between them. If the pores in a given material are small enough, for example less than 100 nanometres in diameter, a molecule will collide more often with the pore walls than with other gas molecules. This will effectively reduce the thermal conductivity of the gas. So, the smaller the pores, the lower the conductivity of the gas”, she says.

[Solar cells]

As part of the project “Bygningsintegrerte solceller for Norge” (Building Integrated Photovoltaics, BIPV Norway), researchers from SINTEF, NTNU, the IFE [IFE Group, privately owned company, located in Sweden] and Teknova [company created by the Nordic Institute for Studies in Innovation {NIFU}, located in Norway], are planning to look into how we can utilise solar cells as integral housing construction components, and how they can be adapted to Norwegian daylight and climatic conditions.

One of the challenges is to develop a solar cell which prevents the accumulation of snow and ice. The cells must be robust enough to withstand harsh wind and weather conditions and have lifetimes that enable them to function as electricity generators.

[Energy]

Today, we spend 90 per cent of our time indoors. This is as much as three times more than in the 1950s. We are also letting less daylight into our buildings as a result of energy considerations and construction engineering requirements. Research shows that daylight is very important to our health, well-being and biological rhythms. It also promotes productivity and learning. So the question is – is it possible to save energy and get the benefits of greater exposure to daylight?

Technologies involving thermochromic, photochromic and electrochromic pigments can help us to control how sunlight enters our buildings, all according to our requirements for daylight and warmth from the sun.

Self-healing concrete

Every year, between 40 and 120 million Euros are spent in Europe on the maintenance of bridges, tunnels and construction walls. These time-consuming and costly activities have to be reduced, and the project CAPDESIGN is aiming to make a contribution in this field.

The objective of the project is to produce concrete that can be ‘restored’ after being exposed to loads and stresses by means of self-healing agents that prevent the formation of cracks. The method involves mixing small capsules into the wet concrete before it hardens. These remain in the matrix until loads or other factors threaten to crack it. The capsules then burst and the self-healing agents are released to repair the structure.

At SINTEF, researchers are working with the material that makes up the capsule shells. The shell has to be able to protect the self-healing agent in the capsules for an extended period and then, under the right conditions, break down and release the agents in response to the formation of cracks caused by temperature, pH, or a load or stress resulting from an impact or shaking. At the same time, the capsules must not impair the ductility or the mechanical properties of the newly-mixed concrete.

You’ll notice most of the research seems to be taking place in Norway. I suspect that is due to the story having come from a joint Norwegian Norwegian University of Science and Technology (NTNU)/SINTEF, website, Gemini.no/en. Anyone wishing to test their Norwegian readings skills need only omit ‘/en’ from the URL.

Nanotech and the oil and gas industry: a webinar

How serendipitous! I stumbled on an announcement from Park Systems for a webinar designed for the oil and gas industry after my June 8, 2015 post featuring Abakan and its new Alberta (Canada)-based cladding facility designed for oil and gas pipes in particular. From a June 8, 2015 news item on Nanowerk,

Park Systems, world-leader in atomic force microscopy (AFM) today announced a webinar to provide next generation technology to improve oil and gas production in both traditional drilling and hydraulic fracturing for oil & gas producers and equipment manufacturers as they continue to pursue the latest developments in production efficiencies.

A June 8, 2015 Park Systems news release, which originated the news item, expands on the theme,

The oil and gas industry is ripe for innovation and the cost of extracting oil can be reduced. Research at PETRO Case Consortium is uncovering new materials, chemicals and coatings that improves yield and reduce costs and with an eye towards diminishing the impact on our environment. This webinar is part of an ongoing series offered by Park System’s new Nano Academy, a platform for providing education and shared knowledge on the latest advancements across a wide spectrum of nanosciences.

This webinar titled Nanostructured Polymers and Nanomaterials for Oil & Gas will be given June 11 [2015] by Dr. Rigoberto Advincula, Director of the Petro Case Consortium and Professor with the Department of Macromolecular Science and Engineering at Case Western Reserve University and is designed to offer innovations in microscopy nanotechnology for oil & gas producers and suppliers.

“Our best in class AFM equipment registers nanoparticle observations and analysis not previously available that extends the ability to analyze chemicals and materials to develop the optimum efficiency,” said Keibock Lee, President of Park Systems. “We are proud to offer this webinar for the oil & gas industry, showcasing Dr. Advincula’s outstanding contribution towards cost reduction and sustainability for the current energy producers and paving the way for future innovations that can enable global energy solutions.”

PETRO Case Consortium at Case Western [Reserve] University, led by Dr. Advincula, is working hard to ensure that the industry can catch up with new technology and apply it to oil & gas production that improves productivity by creating longer lasting concrete, coatings and apply other methods to increase yield in production. This webinar is the first of a series that will cover multiple topics related to nano scale developments across a wide variety of research applications and bio scientific fields.
“Hydraulic fracturing and directional drilling has unlocked many resources,” states Dr. Advincula. “Revolutionary new microscopy technology provided thru Park Systems AFM (Atomic Force Microscopy) and new innovations in chemical and material research indicates that there is a defined opportunity to use the advances in chemistry, materials, and nanoscience to make valuable industry process updates.”

For the last 10 years there has been an increase in interest and research for new materials useful for upstream, midstream, and downstream processes to effectively find function in demanding environments including directional drilling and hydraulic fracturing. High temperature high pressure (HT/HP) and brine conditions pose a challenge for emulsification, demulsification, and viscosity of drilling fluids. Usually the “easy” oil or conventional oil has allowed technologies even dating back to the first oil well in Pennsylvania to become very profitable. But with high pressure high temperature (HPHT) conditions in the most challenging wells, many of the established technologies and materials do not suffice.

The discovery driven group, PETRO Case Consortium at Case Western University, a Park AFM user, investigates the area of molecular, macromolecular, and supramolecular synthesis and structure of polymers and nanomaterials capable of controlled-assembly to form ultrathin films and dispersions with the aim of finding new technologies and materials that improve and replace established oil and gas field formations.

For instance, the evaluation of chemicals and changing or altering the formulas can greatly improve production yields. Different chemicals used for the field include inhibitors for scaling, fouling, corrosion, asphaltene control, formation damage, differential pressures in multiphase environments which will be met by new synthesis methods including metathesis reactions, bio based feedstocks, new polymer surfactants, living polymers, and nanoparticle. Other uses of new chemical technologies include tracers and reporters for geomapping and well connectivity, as well as different types of fluid loss agents that prevent formation damage or keep well integrity, and smart and stimuli-responsive nanoparticles that can be used for improving gelation.

This webinar is available at no cost and is part of Park Systems Nano Academy which will offer valuable education and shared knowledge across many Nano Science Disciplines and Industries as a way to further enable NanoScale advancements. To register go to: http://bit.do/polyoilgas

Webinar logistics (from the Park Systems news release),

About Webinar
Title: Nanostructured Polymers and Nanomaterials for Oil & Gas
Date: June 11, 2015
Time: 9am PST
To Register, go to: http://bit.do/polyoilgas
Pre-requisite: Knowledge of oil field chemicals and rubber materials is preferred but not required.

Here’s more about the expert (from the news release),

About Prof. Rigoberto Advincula
Prof. Rigoberto Advincula, Director of the Petro Case Consortium, is recognized industry-wide as an expert regarding polymer and materials challenges of the oil-gas industry. He is currently a Professor with the Department of Macromolecular Science and Engineering at Case Western Reserve University and is the recipient of numerous awards including Fellow of the American Chemical Society, Herman Mark Scholar Award of the Polymer Division, and Humboldt Fellow.

The news release also included some information about Park Systems,

About Park Systems
Park Systems is a world-leading manufacturer of atomic force microscopy (AFM) systems with a complete range of products for researchers and industry engineers in chemistry, materials, physics, life sciences, semiconductor and data storage industries. Park’s products are used by over a thousand of institutions and corporations worldwide. Park’s AFM provides highest data accuracy at nanoscale resolution, superior productivity, and lowest operating cost thanks to its unique technology and innovative engineering. Park Systems, Inc. is headquartered in Santa Clara, California with its global manufacturing, and R&D headquarters in Korea. Park’s products are sold and supported worldwide with regional headquarters in the US, Korea, Japan, and Singapore, and distribution partners throughout Europe, Asia, and America. Please visit http://www.parkafm.com or call 408-986-1110 for more information.

So there you have it.