Tag Archives: University of Michigan

No more kevlar-wrapped lithium-ion batteries?

Current lithium-ion batteries present a fire hazard, which is why, last, year a team of researchers at the University of Michigan came up with a plan to prevent fires by wrapping the batteries in kevlar. My Jan. 30, 2015 post describes the research and provides some information about airplane fires caused by the use of lithium-ion batteries.

This year, a team of researchers at Stanford University (US) have invented a lithium-ion (li-ion) battery that shuts itself down when it overheats, according to a Jan. 12, 2016 news item on Nanotechnology Now,

Stanford researchers have developed the first lithium-ion battery that shuts down before overheating, then restarts immediately when the temperature cools.

The new technology could prevent the kind of fires that have prompted recalls and bans on a wide range of battery-powered devices, from recliners and computers to navigation systems and hoverboards [and on airplanes].

“People have tried different strategies to solve the problem of accidental fires in lithium-ion batteries,” said Zhenan Bao, a professor of chemical engineering at Stanford. “We’ve designed the first battery that can be shut down and revived over repeated heating and cooling cycles without compromising performance.”

Stanford has produced a video of Dr. Bao discussing her latest work,

A Jan. 11, 2016 Stanford University news release by Mark Schwartz, which originated the news item, provides more detail about li-ion batteries and the new fire prevention technology,

A typical lithium-ion battery consists of two electrodes and a liquid or gel electrolyte that carries charged particles between them. Puncturing, shorting or overcharging the battery generates heat. If the temperature reaches about 300 degrees Fahrenheit (150 degrees Celsius), the electrolyte could catch fire and trigger an explosion.

Several techniques have been used to prevent battery fires, such as adding flame retardants to the electrolyte. In 2014, Stanford engineer Yi Cui created a “smart” battery that provides ample warning before it gets too hot.

“Unfortunately, these techniques are irreversible, so the battery is no longer functional after it overheats,” said study co-author Cui, an associate professor of materials science and engineering and of photon science. “Clearly, in spite of the many efforts made thus far, battery safety remains an important concern and requires a new approach.”

Nanospikes

To address the problem Cui, Bao and postdoctoral scholar Zheng Chen turned to nanotechnology. Bao recently invented a wearable sensor to monitor human body temperature. The sensor is made of a plastic material embedded with tiny particles of nickel with nanoscale spikes protruding from their surface.

For the battery experiment, the researchers coated the spiky nickel particles with graphene, an atom-thick layer of carbon, and embedded the particles in a thin film of elastic polyethylene.

“We attached the polyethylene film to one of the battery electrodes so that an electric current could flow through it,” said Chen, lead author of the study. “To conduct electricity, the spiky particles have to physically touch one another. But during thermal expansion, polyethylene stretches. That causes the particles to spread apart, making the film nonconductive so that electricity can no longer flow through the battery.”

When the researchers heated the battery above 160 F (70 C), the polyethylene film quickly expanded like a balloon, causing the spiky particles to separate and the battery to shut down. But when the temperature dropped back down to 160 F (70 C), the polyethylene shrunk, the particles came back into contact, and the battery started generating electricity again.

“We can even tune the temperature higher or lower depending on how many particles we put in or what type of polymer materials we choose,” said Bao, who is also a professor, by courtesy, of chemistry and of materials science and engineering. “For example, we might want the battery to shut down at 50 C or 100 C.”

Reversible strategy

To test the stability of new material, the researchers repeatedly applied heat to the battery with a hot-air gun. Each time, the battery shut down when it got too hot and quickly resumed operating when the temperature cooled.

“Compared with previous approaches, our design provides a reliable, fast, reversible strategy that can achieve both high battery performance and improved safety,” Cui said. “This strategy holds great promise for practical battery applications.”

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

Fast and reversible thermoresponsive polymer switching materials for safer batteries by Zheng Chen, Po-Chun Hsu, Jeffrey Lopez, Yuzhang Li, John W. F. To, Nan Liu, Chao Wang, Sean C. Andrews, Jia Liu, Yi Cui, & Zhenan Bao. Nature Energy 1, Article number: 15009 (2016) doi:10.1038/nenergy.2015.9 Published online: 11 January 2016

This paper appears to be open access.

Digital alchemy from the University of Michigan (US)

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Describing this work as ‘digital alchemy’ seems like a bit of a stretch as lead is not being turned into gold digitally or otherwise, from an Oct. 30, 2015 news item on Azonano,

Alchemy left the mainstream centuries ago, but one of its core concepts, transmuting the elements, is experiencing a revival in nanotechnology.

Researchers at the University of Michigan are charting a path toward materials with new properties by cleverly altering the nanoparticles used to build them.

An Oct. 27, 2015 University of Michigan news release, which originated the news item, provides more details from the scientists,

“Today, scientists achieve something akin to alchemy when we change materials’ building blocks by adding atoms or molecules to them, or even changing their shape. Such changes affect how the building blocks fit together, which in turn controls material’s behavior and properties,” said Sharon Glotzer, the John Werner Cahn Distinguished University Professor of Engineering and the Stuart W. Churchill Collegiate Professor of Chemical Engineering.

“We’ve developed a new theoretical tool that can be used by computers to carry out ‘alchemy’ on the fly, rapidly searching for the best building block for a given application. Digital alchemy will transform the way we design materials.”

Nanoparticles have the potential to redefine the “elements” available to materials scientists, going from the 90 stable elements to an infinite palette of tiny synthetic particles, just a few hundred times the size of the atoms themselves. The researchers propose a way to navigate the new frontier of nanoscale building blocks not by making and measuring each particle, but by exploring why particles build certain types of structures. Then, the important attributes can be identified and applied to design particles that will produce those structures.

“It seems like having an infinitude of new ‘elements’ to make materials from is a great thing. But if we don’t know the rules they use to organize themselves, and we can’t determine the rules by trial and error because we can’t make all the different elements, then we need to approach developing materials in a new way,” said Greg van Anders, a research fellow in the Glotzer group and first author of the study.

“Rapidly scanning through building blocks is not just a useful way of finding good candidates for new materials, but a necessary step to deal with the tremendous flexibility we now have in making particles.”

To demonstrate the concept, the team used a computer simulation that arranged a set of particles into a structure and then allowed the shape of the particles to change.

“We just stick the particles into a structure and say ‘find a shape that you’re happy with if you have to sit in that structure,'” van Anders said.

It had been assumed that the best shape for self-assembling into a particular structure is the one that packs into that structure most efficiently, leaving very little empty space. To test this, the team simulated the self-organization of four-sided pyramids (known as tetrahedra). They pack efficiently into a diamond structure—the structure produced by carbon atoms in a diamond—if their points are cut off. But if the diamond structure is the goal, how much of the points should be removed?

Not as much as needed for the closest packing, van Anders said. The shapes self-assembled best if the points were left a little longer, better preserving the tetrahedral character.

The team also explored what happens when ripples of attraction and repulsion run through a collection of spherical particles. This causes the particles to arrange themselves with respect to their neighbors. When these ripples are timed in a certain way, the particles form an icosahedral quasicrystal, an intricate structure that is symmetrical but doesn’t have a repeating structural unit.

“It’s one of the most complicated structures we know,” van Anders said. “If we could understand how to control the interactions so that this structure forms better, then chances are, we could also figure out how to make less complicated structures in systems that use a different set of interactions.”

This could help researchers build structures by exposing a fluid containing nanoparticles to forces such as light, electric fields and magnetic fields. These capabilities could lead to many interesting advances. One of Glotzer’s particular interests is in materials that can change color on command, creating the ultimate camouflage.

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

Digital Alchemy for Materials Design: Colloids and Beyond by Greg van Anders, Daphne Klotsa, Andrew S. Karas, Paul M. Dodd, and Sharon C. Glotzer. ACS Nano, 2015, 9 (10), pp 9542–9553 DOI: 10.1021/acsnano.5b04181 Publication Date (Web): September 24, 2015

Copyright © 2015 American Chemical Society

This paper is behind a paywall.

Cell-to-cell communication via nanotubes

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It turns out that the cells communicating with each other are located in fruit flies. So, it’s perhaps not quite as exciting as one might have imagined, nonetheless, a July 1, 2015 news item on ScienceDaily provides some intriguing insights into cell communication,

When it comes to communicating with each other, some cells may be more “old school” than was previously thought.

Certain types of stem cells use microscopic, threadlike nanotubes to communicate with neighboring cells, like a landline phone connection, rather than sending a broadcast signal, researchers at University of Michigan Life Sciences Institute and University of Texas Southwestern Medical Center have discovered.

The findings, which are scheduled for online publication July 1 in Nature, offer new insights on how stem cells retain their identities when they divide to split off a new, specialized cell.

The fruit-fly research also suggests that short-range, cell-to-cell communication may rely on this type of direct connection more than was previously understood, said co-senior author Yukiko Yamashita, a U-M developmental biologist whose lab is located at the Life Sciences Institute.

A July 1, 2015 University of Michigan news release (also on EurekAlert), which originated the news item, expands on the theme,

“There are trillions of cells in the human body, but nowhere near that number of signaling pathways,” she said. “There’s a lot we don’t know about how the right cells get just the right messages to the right recipients at the right time.”

The nanotubes had actually been hiding in plain sight.

The investigation began when a postdoctoral researcher in Yamashita’s lab, Mayu Inaba, approached her mentor with questions about tiny threads of connection she noticed in an image of fruit fly reproductive stem cells, which are also known as germ line cells. The projections linked individual stem cells back to a central hub in the stem cell “niche.” Niches create a supportive environment for stem cells and help direct their activity.

Yamashita, a Howard Hughes Medical Institute investigator, MacArthur Fellow and an associate professor at the U-M Medical School, looked through her old image files and discovered that the connections appeared in numerous images.

“I had seen them, but I wasn’t seeing them,” Yamashita said. “They were like a little piece of dust on an otherwise normal picture. After we presented our findings at meetings, other scientists who work with the same cells would say, ‘We see them now, too.'”

It’s not surprising that the minute structures went overlooked for so long. Each one is about 3 micrometers long; by comparison, a piece of paper is 100 micrometers thick.

While the study looked specifically at reproductive cells in male Drosophila fruit flies, there have been indications of similar structures in other contexts, including mammalian cells, Yamashita said.

Fruit flies are an important model for this type of investigation, she added. If one was to start instead with human cells, one might find something, but the system’s greater complexity would make it far more difficult to tease apart the underlying mechanisms.

The findings shed new light on a key attribute of stem cells: their ability to make new specialized cells while still retaining their identity as stem cells.

Germ line stem cells typically divide asymmetrically. In the male fruit fly, when a stem cell divides, one part stays attached to the hub and remains a stem cell. The other part moves away from the hub and begins differentiation into a fly sperm cell.

Until the discovery of the nanotubes, scientists had been puzzled as to how cellular signals guiding identity could act on one of the cells but not the other, said collaborator Michael Buszczak, an associate professor of molecular biology at UT Southwestern, who shares corresponding authorship of the paper and currently co-mentors Inaba with Yamashita.

The researchers conducted experiments that showed disruption of nanotube formation compromised the ability of the germ line stem cells to renew themselves.

I gather the fruit fly research offers the basis for more extensive investigations into other species and their cell-to-cell communication.

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

Nanotubes mediate niche–stem-cell signalling in the Drosophila testis by Mayu Inaba, Michael Buszczak, & Yukiko M. Yamashita. Nature (2015) doi:10.1038/nature14602 Published online 01 July 2015

This paper is behind a paywall.

A hedgehog particle for safer paints and coatings?

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The researchers did not extract particles from hedgehogs for this work but they are attempting to provide a description for a class of particles, which could make paints and coatings more environmentally friendly. From a Jan. 28, 2015 news item on phys.org,

A new process that can sprout microscopic spikes on nearly any type of particle may lead to more environmentally friendly paints and a variety of other innovations. Made by a team of University of Michigan engineers, the “hedgehog particles” are named for their bushy appearance under the microscope. …

A Jan. 28, 2015 University of Michigan news release (also EurekAlert), which originated the news item, describes the research,

The new process modifies oily, or hydrophobic, particles, enabling them to disperse easily in water. It can also modify water-soluble, or hydrophilic, particles, enabling them to dissolve in oil or other oily chemicals.

The unusual behavior of the hedgehog particles came as something of a surprise to the research team, says Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering.

“We thought we’d made a mistake,” Kotov said. “We saw these particles that are supposed to hate water dispersing in it and we thought maybe the particles weren’t hydrophobic, or maybe there was a chemical layer that was enabling them to disperse. But we double-checked everything and found that, in fact, these particles defy the conventional chemical wisdom that we all learned in high school.”

The team found that the tiny spikes made the particles repel each other more and attract each other less. The spikes also dramatically reduce the particles’ surface area, helping them to diffuse more easily.

One of the first applications for the particles is likely to be in paints and coatings, where toxic volatile organic compounds (VOCs) like toluene are now used to dissolve pigment. Pigments made from hedgehog particles could potentially be dissolved in nontoxic carriers like water, the researchers say.

This would result in fewer VOC emissions from paints and coatings, which the EPA [US Environmental Protection Agency] estimates at over eight million tons per year in the United States alone. VOCs can cause a variety of respiratory and other ailments and also contribute to smog and climate change. Reducing their use has become a priority for the Environmental Protection Agency and other regulatory bodies worldwide.

“VOC solvents are toxic, they’re flammable, they’re expensive to handle and dispose of safely,” Kotov said. “So if you can avoid using them, there’s a significant cost savings in addition to environmental benefits.”

While some low- and no-VOC coatings are already available, Kotov says hedgehog particles could provide a simpler, more versatile and less expensive way to manufacture them.

For the study, the team created hedgehog particles by growing zinc oxide spikes on polystyrene microbeads. The researchers say that a key advantage of the process is its flexibility; it can be performed on virtually any type of particle, and makers can vary the number and size of the spikes by adjusting the amount of time the particles sit in various solutions while the protrusions are growing. They can also make the spikes out of materials other than zinc oxide.

“I think one thing that’s really exciting about this is that we’re able to make such a wide variety of hedgehog particles,” said Joong Hwan Bahng, a chemical engineering doctoral student. “It’s very controllable and very versatile.”

The researchers say the process is also easily scalable, enabling hedgehog particles to be created “by the bucketful,” according to Kotov. Further down the road, Kotov envisions a variety of other applications, including better oil dispersants that could aid in the cleanup of oil spills and better ways to deliver non-water-soluble prescription medications.

As is becoming more common in news releases, there’s a reference to commercial partners, suggesting (to me) they might be open to offers,

“Anytime you need to dissolve an oily particle in water, there’s a potential application for hedgehog particles,” he said. “It’s really just a matter of finding the right commercial partners. We’re only just beginning to explore the uses for these particles, and I think we’re going to see a lot of applications in the future.”

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

Anomalous dispersions of ‘hedgehog’ particles by Joong Hwan Bahng, Bongjun Yeom, Yichun Wang, Siu On Tung, J. Damon Hoff, & Nicholas Kotov. Nature 517, 596–599 (29 January 2015) doi:10.1038/nature14092 Published online 28 January 2015

This paper is behind a paywall.

Kevlar-wrapped batteries on an airplane

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Researchers at the University of Michigan are not trying to bulletproof lithium-ion batteries with kevlar. Rather, they’re trying prevent fires. From a Jan. 27, 2015 University of Michigan news release (also on EurekAlert),

New battery technology from the University of Michigan should be able to prevent the kind of fires that grounded Boeing 787 Dreamliners in 2013.

The innovation is an advanced barrier between the electrodes in a lithium-ion battery.

Made with nanofibers extracted from Kevlar, the tough material in bulletproof vests, the barrier stifles the growth of metal tendrils that can become unwanted pathways for electrical current.

A U-M team of researchers also founded Ann Arbor-based Elegus Technologies to bring this research from the lab to market. Mass production is expected to begin in the fourth quarter 2016.

“Unlike other ultra strong materials such as carbon nanotubes, Kevlar is an insulator,” said Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering. “This property is perfect for separators that need to prevent shorting between two electrodes.”

Lithium-ion batteries work by shuttling lithium ions from one electrode to the other. This creates a charge imbalance, and since electrons can’t go through the membrane between the electrodes, they go through a circuit instead and do something useful on the way.

But if the holes in the membrane are too big, the lithium atoms can build themselves into fern-like structures, called dendrites, which eventually poke through the membrane. If they reach the other electrode, the electrons have a path within the battery, shorting out the circuit. This is how the battery fires on the Boeing 787 are thought to have started.

“The fern shape is particularly difficult to stop because of its nanoscale tip,” said Siu On Tung, a graduate student in Kotov’s lab, as well as chief technology officer at Elegus. “It was very important that the fibers formed smaller pores than the tip size.”

While the widths of pores in other membranes are a few hundred nanometers, or a few hundred-thousandths of a centimeter, the pores in the membrane developed at U-M are 15-to-20 nanometers across. They are large enough to let individual lithium ions pass, but small enough to block the 20-to-50-nanometer tips of the fern-structures.

The researchers made the membrane by layering the fibers on top of each other in thin sheets. This method keeps the chain-like molecules in the plastic stretched out, which is important for good lithium-ion conductivity between the electrodes, Tung said.

“The special feature of this material is we can make it very thin, so we can get more energy into the same battery cell size, or we can shrink the cell size,” said Dan VanderLey, an engineer who helped found Elegus through U-M’s Master of Entrepreneurship program. “We’ve seen a lot of interest from people looking to make thinner products.”

Thirty companies have requested samples of the material.

Kevlar’s heat resistance could also lead to safer batteries as the membrane stands a better chance of surviving a fire than most membranes currently in use.

While the team is satisfied with the membrane’s ability to block the lithium dendrites, they are currently looking for ways to improve the flow of loose lithium ions so that batteries can charge and release their energy more quickly.

For anyone unfamiliar with the Boeing 787 Dreamliner fires, caused by lithium-ion batteries, these Boeing fires and others are mentioned in my May 29, 2013 post (Life-cycle assessment for electric vehicle lithium-ion batteries and nanotechnology is a risk analysis) scroll down about 50% of the way.

As for the research paper, here’s a link and a citation,

A dendrite-suppressing composite ion conductor from aramid nanofibres by Siu-On Tung, Szushen Ho, Ming Yang, Ruilin Zhang, & Nicholas A. Kotov. Nature Communications 6, Article number: 6152 doi:10.1038/ncomms7152 Published 27 January 2015

This paper is behind a paywall.

You can find out more about Elegus Technologies here.

FrogHeart and 2014: acknowledging active colleagues and saying good-bye to defunct blogs and hello to the new

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It’s been quite the year. In Feb. 2014, TED offered me free livestreaming of the event in Vancouver. In March/April 2014, Google tweaked its search function and sometime in September 2014 I decided to publish two pieces per day rather than three with the consequence that the visit numbers for this blog are lower than they might otherwise have been. More about statistics and traffic to this blog will be in the post I usually publish just the new year has started.

On other fronts, I taught two courses (Bioelectronics and Nanotechnology, the next big idea) this year for Simon Fraser University (Vancouver, Canada) in its Continuing Studies (aka Lifelong Learning) programmes. I also attended a World Congress on Alternatives to Animal Testing in the Life Sciences in Prague. The trip, sponsored by SEURAT-1 (Safety Evaluation Ultimately Replacing Animal Testing), will result in a total of five stories, the first having been recently (Dec. 26, 2014) published. I’m currently preparing a submission for the International Symposium on Electronic Arts being held in Vancouver in August 2015 based on a project I have embarked upon, ‘Steep’. Focused on gold nanoparticles, the project is Raewyn Turner‘s (an artist from New Zealand) brainchild. She has kindly opened up the project in such a way that I too can contribute. There are two other members of the Steep project, Brian Harris, an electrical designer, who works closely with Raewyn on a number of arts projects and there’s Mark Wiesner as our science consultant. Wiesner is a professor of civil and environmental engineering,at Duke University in North Carolina.

There is one other thing which you may have noticed, I placed a ‘Donate’ button on the blog early in 2014.

Acknowledgements, good-byes, and hellos

Dexter Johnson on his Nanoclast blog (on the IEEE [Institute of Electrical and Electronics Engineers] website) remains a constant in the nano sector of the blogosphere where he provides his incisive opinions and context for the nano scene.

David Bruggeman on his Pasco Phronesis blog offers valuable insight into the US science policy scene along with a lively calendar of art/science events and an accounting of the science and technology guests on late night US television.

Andrew Maynard archived his 2020 Science blog in July 2014 but he does continue writing and communication science as director of the University of Michigan Risk Science Center. Notably, Andrew continues to write, along with other contributors, on the Risk Without Borders blog at the University of Michigan.

Sadly, Cientifica, a emerging technologies business consultancy, where Tim Harper published a number of valuable white papers, reports, and blog postings is no longer with us. Happily, Tim continues with an eponymous website where he blogs and communicates about various business interests, “I’m currently involved in graphene, nanotechnology, construction, heating, and biosensing, working for a UK public company, as well as organisations ranging from MIT [Massachusetts Institute of Technology] to the World Economic Forum.” Glad to you’re back to blogging Tim. I missed your business savvy approach and occasional cheekiness!

I was delighted to learn of a new nano blog, NanoScéal, this year and relieved to see they’re hanging in. Their approach is curatorial where they present a week of selected nano stories. I don’t think a lot of people realize how much work a curatorial approach requires. Bravo!

Sir Martyn Poliakoff and the Periodic Table of Videos

Just as I was wondering what happened to the Periodic Table of Videos (my April 25, 2011 post offers a description of the project) Grrl Scientist on the Guardian science blog network offers information about one of the moving forces behind the project, Martyn Poliakoff in a Dec. 31, 2014 post,

This morning [Dec. 31, 2014], I was most pleased to learn that Martyn Poliakoff, professor of chemistry at the University of Nottingham, was awarded a bachelor knighthood by the Queen. So pleased was I that I struggled out of bed (badly wrecked back), my teeth gritted, so I could share this news with you.

…

Now Professor Poliakoff — who now is more properly known as Professor SIR Martyn Poliakoff — was awarded one of the highest civilian honours in the land, and his continued online presence has played a significant role in this.

…

“I think it may be the first time that YouTube has been mentioned when somebody has got a knighthood, and so I feel really quite proud about that. And I also really want to thank you YouTube viewers who have made this possible through your enthusiasm for chemistry.”

As for the Periodic Table of Videos, the series continues past the 118 elements currently identified to a include discussions on molecules.

Science Borealis, the Canadian science blog aggregator, which I helped to organize (albeit desultorily), celebrated its first full year of operation. Congratulations to all those who worked to make this project such a success that it welcomed its 100th blog earlier this year. From a Sept. 24, 2014 news item on Yahoo (Note: Links have been removed),

This week the Science Borealis team celebrated the addition of the 100th blog to its roster of Canadian science blog sites! As was recently noted in the Council of Canadian Academies report on Science Culture, science blogging in Canada is a rapidly growing means of science communication. Our digital milestone is one of many initiatives that are bringing to fruition the vision of a rich Canadian online science communication community.

The honour of being syndicated as the 100th blog goes to Spider Bytes, by Catherine Scott, an MSc [Master of Science] student at Simon Fraser University in Burnaby, British Columbia. …

As always, it’s been a pleasure and privilege writing and publishing this blog. Thank you all for your support whether it comes in the form of reading it, commenting, tweeting, subscribing, and/or deciding to publish your own blog. May you have a wonderful and rewarding 2015!

Like a starfish shell, facetless crystals

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Made by accident, these facetless crystals could prove useful in applications for cells, medications, and more according to researchers at the University of Michigan in an Oct. 20, 2014 news item on Nanowerk,

In a design that mimics a hard-to-duplicate texture of starfish shells, University of Michigan engineers have made rounded crystals that have no facets.

“We call them nanolobes. They look like little hot air balloons that are rising from the surface,” said Olga Shalev, a doctoral student in materials science and engineering who worked on the project.

There is a video with the researcher, Olga Shalev, describing the nanolobes in more detail,

An Oct. 17, 2014 University of Michigan news release (also on EurekAlert*), which originated the news item, offers text for those who prefer to read about the science rather than receive it by video,

Both the nanolobes’ shape and the way they’re made have promising applications, the researchers say. The geometry could potentially be useful to guide light in advanced LEDs, solar cells and nonreflective surfaces. A layer might help a material repel water or dirt. And the process used to manufacture them – organic vapor jet printing – might lend itself to 3D-printing medications that absorb better into the body and make personalized dosing possible.

The nanoscale shapes are made out of boron subphthalocyanine chloride, a material often used in organic solar cells. It’s in a family of small molecular compounds that tend to make either flat films or faceted crystals with sharp edges, says Max Shtein, an associate professor of materials science and engineering, macromolecular science and engineering, chemical engineering, and art and design.

“In my years of working with these kinds of materials, I’ve never seen shapes that looked like these. They’re reminiscent of what you get from biological processes,” Shtein said. “Nature can sometimes produce crystals that are smooth, but engineers haven’t been able to do it reliably.”

Echinoderm sea creatures such as brittle stars have ordered rounded structures on their bodies that work as lenses to gather light into their rudimentary eyes. But in a lab, crystals composed of the same minerals tend either to be faceted with flat faces and sharp angles, or smooth, but lacking molecular order.

The U-M researchers made the curved crystals by accident several years ago. They’ve since traced their steps and figured out how to do it on purpose.

In 2010, Shaurjo Biswas, then a doctoral student at U-M, was making solar cells with the organic vapor jet printer. He was recalibrating the machine after switching between materials. Part of the recalibration process involves taking a close look at the fresh layers of material, of films, printed on a plate. Biswas X-rayed several films of different thicknesses to observe the crystal structure. He noticed that the boron subphthalocyanine chloride, which typically does not form ordered shapes, started to do so once the film got thicker than 600 nanometers. He made some thicker films to see what would happen.

“At first, we wondered if our apparatus was functioning properly,” Shtein said.

At 800 nanometers thick, the repeating nanolobe pattern emerged every time.

For a long while, the blobs were lab curiosities. Researchers were focused on other things. Then doctoral student Shalev got involved. She was fascinated by the structures and wanted to understand the reason for the phenomenon. She repeated the experiments in a modified apparatus that gave more control over the conditions to vary them systematically. She collaborated with physics professor Roy Clarke to gain a better understanding of the crystallization, and mechanical engineering professor Wei Lu to simulate the evolution of the surface.. She’s first author of a paper on the findings published in the current edition of Nature Communications.

“As far as we know, no other technology can do this,” Shalev said.

The organic vapor jet printing process the researchers use is a technique Shtein helped to develop when he was in graduate school. He describes it as spray painting, but with a gas rather than with a liquid. It’s cheaper and easier to do for certain applications than competing approaches that involve stencils or can only be done in a vacuum, Shtein says. He’s especially hopeful about the prospects for this technique to advance emerging 3D-printed pharmaceutical concepts.

For example, Shtein and Shalev believe this method offers a precise way to control the size and shape of the medicine particles, for easier absorption into the body. It could also allow drugs to be attached directly to other materials and it doesn’t require solvents that might introduce impurities.

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

Growth and modelling of spherical crystalline morphologies of molecular materials by O. Shalev, S. Biswas, Y. Yang, T. Eddir, W. Lu, R. Clarke, & M. Shtein. Nature Communications 5, Article number: 5204 doi:10.1038/ncomms6204 Published 16 October 2014

This paper is behind a paywall.

* EurekAlert link added on Oct. 20, 2014 at 1035 hours PDT.

Intel’s 14nm chip: architecture revealed and scientist discusses the limits to computers

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Anxieties about how much longer we can design and manufacture smaller, faster computer chips are commonplace even as companies continue to announce new, faster, smaller chips. Just before the US National Science Foundation (NSF) issued a press release concerning a Nature (journal) essay on the limits of computation, Intel announced a new microarchitecture for its 14nm chips .

First, there’s Intel. In an Aug. 12, 2014 news item on Azonano, Intel announced its newest microarchitecture optimization,

Intel today disclosed details of its newest microarchitecture that is optimized with Intel’s industry-leading 14nm manufacturing process. Together these technologies will provide high-performance and low-power capabilities to serve a broad array of computing needs and products from the infrastructure of cloud computing and the Internet of Things to personal and mobile computing.

An Aug. 11, 2014 Intel news release, which originated the news item, lists key points,

Intel disclosed details of the microarchitecture of the Intel® Core™ M processor, the first product to be manufactured using 14nm.

The combination of the new microarchitecture and manufacturing process will usher in a wave of innovation in new form factors, experiences and systems that are thinner and run silent and cool.

Intel architects and chip designers have achieved greater than two times reduction in the thermal design point when compared to a previous generation of processor while providing similar performance and improved battery life.

The new microarchitecture was optimized to take advantage of the new capabilities of the 14nm manufacturing process.

Intel has delivered the world’s first 14nm technology in volume production. It uses second-generation Tri-gate (FinFET) transistors with industry-leading performance, power, density and cost per transistor.

Intel’s 14nm technology will be used to manufacture a wide range of high-performance to low-power products including servers, personal computing devices and Internet of Things.

The first systems based on the Intel® Core™ M processor will be on shelves for the holiday selling season followed by broader OEM availability in the first half of 2015.

Additional products based on the Broadwell microarchitecture and 14nm process technology will be introduced in the coming months.

The company has made available supporting materials including videos titled, ‘Advancing Moore’s Law in 2014’, ‘Microscopic Mark Bohr: 14nm Explained’, and ‘Intel 14nm Manufacturing Process’ which can be found here. An earlier mention of Intel and its 14nm manufacturing process can be found in my July 9, 2014 posting.

Meanwhile, in a more contemplative mood, Igor Markov of the University of Michigan has written an essay for Nature questioning the limits of computation as per an Aug. 14, 2014 news item on Azonano,

From their origins in the 1940s as sequestered, room-sized machines designed for military and scientific use, computers have made a rapid march into the mainstream, radically transforming industry, commerce, entertainment and governance while shrinking to become ubiquitous handheld portals to the world.

This progress has been driven by the industry’s ability to continually innovate techniques for packing increasing amounts of computational circuitry into smaller and denser microchips. But with miniature computer processors now containing millions of closely-packed transistor components of near atomic size, chip designers are facing both engineering and fundamental limits that have become barriers to the continued improvement of computer performance.

Have we reached the limits to computation?

In a review article in this week’s issue of the journal Nature, Igor Markov of the University of Michigan reviews limiting factors in the development of computing systems to help determine what is achievable, identifying “loose” limits and viable opportunities for advancements through the use of emerging technologies. His research for this project was funded in part by the National Science Foundation (NSF).

An Aug. 13, 2014 NSF news release, which originated the news item, describes Markov’s Nature essay in greater detail,

“Just as the second law of thermodynamics was inspired by the discovery of heat engines during the industrial revolution, we are poised to identify fundamental laws that could enunciate the limits of computation in the present information age,” says Sankar Basu, a program director in NSF’s Computer and Information Science and Engineering Directorate. “Markov’s paper revolves around this important intellectual question of our time and briefly touches upon most threads of scientific work leading up to it.”

The article summarizes and examines limitations in the areas of manufacturing and engineering, design and validation, power and heat, time and space, as well as information and computational complexity.

“What are these limits, and are some of them negotiable? On which assumptions are they based? How can they be overcome?” asks Markov. “Given the wealth of knowledge about limits to computation and complicated relations between such limits, it is important to measure both dominant and emerging technologies against them.”

Limits related to materials and manufacturing are immediately perceptible. In a material layer ten atoms thick, missing one atom due to imprecise manufacturing changes electrical parameters by ten percent or more. Shrinking designs of this scale further inevitably leads to quantum physics and associated limits.

Limits related to engineering are dependent upon design decisions, technical abilities and the ability to validate designs. While very real, these limits are difficult to quantify. However, once the premises of a limit are understood, obstacles to improvement can potentially be eliminated. One such breakthrough has been in writing software to automatically find, diagnose and fix bugs in hardware designs.

Limits related to power and energy have been studied for many years, but only recently have chip designers found ways to improve the energy consumption of processors by temporarily turning off parts of the chip. There are many other clever tricks for saving energy during computation. But moving forward, silicon chips will not maintain the pace of improvement without radical changes. Atomic physics suggests intriguing possibilities but these are far beyond modern engineering capabilities.

Limits relating to time and space can be felt in practice. The speed of light, while a very large number, limits how fast data can travel. Traveling through copper wires and silicon transistors, a signal can no longer traverse a chip in one clock cycle today. A formula limiting parallel computation in terms of device size, communication speed and the number of available dimensions has been known for more than 20 years, but only recently has it become important now that transistors are faster than interconnections. This is why alternatives to conventional wires are being developed, but in the meantime mathematical optimization can be used to reduce the length of wires by rearranging transistors and other components.

Several key limits related to information and computational complexity have been reached by modern computers. Some categories of computational tasks are conjectured to be so difficult to solve that no proposed technology, not even quantum computing, promises consistent advantage. But studying each task individually often helps reformulate it for more efficient computation.

When a specific limit is approached and obstructs progress, understanding the assumptions made is key to circumventing it. Chip scaling will continue for the next few years, but each step forward will meet serious obstacles, some too powerful to circumvent.

What about breakthrough technologies? New techniques and materials can be helpful in several ways and can potentially be “game changers” with respect to traditional limits. For example, carbon nanotube transistors provide greater drive strength and can potentially reduce delay, decrease energy consumption and shrink the footprint of an overall circuit. On the other hand, fundamental limits–sometimes not initially anticipated–tend to obstruct new and emerging technologies, so it is important to understand them before promising a new revolution in power, performance and other factors.

“Understanding these important limits,” says Markov, “will help us to bet on the right new techniques and technologies.”

Here’s a link to and a citation for Markov’s article,

Limits on fundamental limits to computation by Igor L. Markov. Nature 512, 147–154 (14 August 2014) doi:10.1038/nature13570 Published online 13 August 2014

This paper is behind a paywall but a free preview is available via ReadCube Access.

It’s a fascinating question, what are the limits? It’s one being asked not only with regard to computation but also to medicine, human enhancement, and artificial intelligence for just a few areas of endeavour.

Memristor, memristor! What is happening? News from the University of Michigan and HP Laboratories

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Professor Wei Lu (whose work on memristors has been mentioned here a few times [an April 15, 2010 posting and an April 19, 2012 posting]) has made a discovery about memristors with significant implications (from a June 25, 2014 news item on Azonano),

In work that unmasks some of the magic behind memristors and “resistive random access memory,” or RRAM—cutting-edge computer components that combine logic and memory functions—researchers have shown that the metal particles in memristors don’t stay put as previously thought.

The findings have broad implications for the semiconductor industry and beyond. They show, for the first time, exactly how some memristors remember.

A June 24, 2014 University of Michigan news release, which originated the news item, includes Lu’s perspective on this discovery and more details about it,

“Most people have thought you can’t move metal particles in a solid material,” said Wei Lu, associate professor of electrical and computer engineering at the University of Michigan. “In a liquid and gas, it’s mobile and people understand that, but in a solid we don’t expect this behavior. This is the first time it has been shown.”

…

Lu, who led the project, and colleagues at U-M and the Electronic Research Centre Jülich in Germany used transmission electron microscopes to watch and record what happens to the atoms in the metal layer of their memristor when they exposed it to an electric field. The metal layer was encased in the dielectric material silicon dioxide, which is commonly used in the semiconductor industry to help route electricity.

They observed the metal atoms becoming charged ions, clustering with up to thousands of others into metal nanoparticles, and then migrating and forming a bridge between the electrodes at the opposite ends of the dielectric material.

They demonstrated this process with several metals, including silver and platinum. And depending on the materials involved and the electric current, the bridge formed in different ways.

The bridge, also called a conducting filament, stays put after the electrical power is turned off in the device. So when researchers turn the power back on, the bridge is there as a smooth pathway for current to travel along. Further, the electric field can be used to change the shape and size of the filament, or break the filament altogether, which in turn regulates the resistance of the device, or how easy current can flow through it.

Computers built with memristors would encode information in these different resistance values, which is in turn based on a different arrangement of conducting filaments.

Memristor researchers like Lu and his colleagues had theorized that the metal atoms in memristors moved, but previous results had yielded different shaped filaments and so they thought they hadn’t nailed down the underlying process.

“We succeeded in resolving the puzzle of apparently contradicting observations and in offering a predictive model accounting for materials and conditions,” said Ilia Valov, principle investigator at the Electronic Materials Research Centre Jülich. “Also the fact that we observed particle movement driven by electrochemical forces within dielectric matrix is in itself a sensation.”

The implications for this work (from the news release),

The results could lead to a new approach to chip design—one that involves using fine-tuned electrical signals to lay out integrated circuits after they’re fabricated. And it could also advance memristor technology, which promises smaller, faster, cheaper chips and computers inspired by biological brains in that they could perform many tasks at the same time.

As is becoming more common these days (from the news release),

Lu is a co-founder of Crossbar Inc., a Santa Clara, Calif.-based startup working to commercialize RRAM. Crossbar has just completed a $25 million Series C funding round.

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

Electrochemical dynamics of nanoscale metallic inclusions in dielectrics by Yuchao Yang, Peng Gao, Linze Li, Xiaoqing Pan, Stefan Tappertzhofen, ShinHyun Choi, Rainer Waser, Ilia Valov, & Wei D. Lu. Nature Communications 5, Article number: 4232 doi:10.1038/ncomms5232 Published 23 June 2014

This paper is behind a paywall.

The other party instrumental in the development and, they hope, the commercialization of memristors is HP (Hewlett Packard) Laboratories (HP Labs). Anyone familiar with this blog will likely know I have frequently covered the topic starting with an essay explaining the basics on my Nanotech Mysteries wiki (or you can check this more extensive and more recently updated entry on Wikipedia) and with subsequent entries here over the years. The most recent entry is a Jan. 9, 2014 posting which featured the then latest information on the HP Labs memristor situation (scroll down about 50% of the way). This new information is more in the nature of a new revelation of details rather than an update on its status. Sebastian Anthony’s June 11, 2014 article for extremetech.com lays out the situation plainly (Note: Links have been removed),

HP, one of the original 800lb Silicon Valley gorillas that has seen much happier days, is staking everything on a brand new computer architecture that it calls… The Machine. Judging by an early report from Bloomberg Businessweek, up to 75% of HP’s once fairly illustrious R&D division — HP Labs – are working on The Machine. As you would expect, details of what will actually make The Machine a unique proposition are hard to come by, but it sounds like HP’s groundbreaking work on memristors (pictured top) and silicon photonics will play a key role.

…

First things first, we’re probably not talking about a consumer computing architecture here, though it’s possible that technologies commercialized by The Machine will percolate down to desktops and laptops. Basically, HP used to be a huge player in the workstation and server markets, with its own operating system and hardware architecture, much like Sun. Over the last 10 years though, Intel’s x86 architecture has rapidly taken over, to the point where HP (and Dell and IBM) are essentially just OEM resellers of commodity x86 servers. This has driven down enterprise profit margins — and when combined with its huge stake in the diminishing PC market, you can see why HP is rather nervous about the future. The Machine, and IBM’s OpenPower initiative, are both attempts to get out from underneath Intel’s x86 monopoly.

…

While exact details are hard to come by, it seems The Machine is predicated on the idea that current RAM, storage, and interconnect technology can’t keep up with modern Big Data processing requirements. HP is working on two technologies that could solve both problems: Memristors could replace RAM and long-term flash storage, and silicon photonics could provide faster on- and off-motherboard buses. Memristors essentially combine the benefits of DRAM and flash storage in a single, hyper-fast, super-dense package. Silicon photonics is all about reducing optical transmission and reception to a scale that can be integrated into silicon chips (moving from electrical to optical would allow for much higher data rates and lower power consumption). Both technologies can be built using conventional fabrication techniques.

In a June 11, 2014 article by Ashlee Vance for Bloomberg Business Newsweek, the company’s CTO (Chief Technical Officer), Martin Fink provides new details,

That’s what they’re calling it at HP Labs: “the Machine.” It’s basically a brand-new type of computer architecture that HP’s engineers say will serve as a replacement for today’s designs, with a new operating system, a different type of memory, and superfast data transfer. The company says it will bring the Machine to market within the next few years or fall on its face trying. “We think we have no choice,” says Martin Fink, the chief technology officer and head of HP Labs, who is expected to unveil HP’s plans at a conference Wednesday [June 11, 2014].

In my Jan. 9, 2014 posting there’s a quote from Martin Fink stating that 2018 would be earliest date for the company’s StoreServ arrays to be packed with 100TB Memristor drives (the Machine?). The company later clarified the comment by noting that it’s very difficult to set dates for new technology arrivals.

Vance shares what could be a stirring ‘origins’ story of sorts, provided the Machine is successful,

The Machine started to take shape two years ago, after Fink was named director of HP Labs. Assessing the company’s projects, he says, made it clear that HP was developing the needed components to create a better computing system. Among its research projects: a new form of memory known as memristors; and silicon photonics, the transfer of data inside a computer using light instead of copper wires. And its researchers have worked on operating systems including Windows, Linux, HP-UX, Tru64, and NonStop.

Fink and his colleagues decided to pitch HP Chief Executive Officer Meg Whitman on the idea of assembling all this technology to form the Machine. During a two-hour presentation held a year and a half ago, they laid out how the computer might work, its benefits, and the expectation that about 75 percent of HP Labs personnel would be dedicated to this one project. “At the end, Meg turned to [Chief Financial Officer] Cathie Lesjak and said, ‘Find them more money,’” says John Sontag, the vice president of systems research at HP, who attended the meeting and is in charge of bringing the Machine to life. “People in Labs see this as a once-in-a-lifetime opportunity.”

Here is the memristor making an appearance in Vance’s article,

HP’s bet is the memristor, a nanoscale chip that Labs researchers must build and handle in full anticontamination clean-room suits. At the simplest level, the memristor consists of a grid of wires with a stack of thin layers of materials such as tantalum oxide at each intersection. When a current is applied to the wires, the materials’ resistance is altered, and this state can hold after the current is removed. At that point, the device is essentially remembering 1s or 0s depending on which state it is in, multiplying its storage capacity. HP can build these chips with traditional semiconductor equipment and expects to be able to pack unprecedented amounts of memory—enough to store huge databases of pictures, files, and data—into a computer.

…

New memory and networking technology requires a new operating system. Most applications written in the past 50 years have been taught to wait for data, assuming that the memory systems feeding the main computers chips are slow. Fink has assigned one team to develop the open-source Machine OS, which will assume the availability of a high-speed, constant memory store. …

Peter Bright in his June 11, 2014 article for Ars Technica opens his article with a controversial statement (Note: Links have been removed),

In 2008, scientists at HP invented a fourth fundamental component to join the resistor, capacitor, and inductor: the memristor. [emphasis mine] Theorized back in 1971, memristors showed promise in computing as they can be used to both build logic gates, the building blocks of processors, and also act as long-term storage.

Whether or not the memristor is a fourth fundamental component has been a matter of some debate as you can see in this Memristor entry (section on Memristor definition and criticism) on Wikipedia.

Bright goes on to provide a 2016 delivery date for some type of memristor-based product and additional technical insight about the Machine,

… By 2016, the company plans to have memristor-based DIMMs, which will combine the high storage densities of hard disks with the high performance of traditional DRAM.

John Sontag, vice president of HP Systems Research, said that The Machine would use “electrons for processing, photons for communication, and ions for storage.” The electrons are found in conventional silicon processors, and the ions are found in the memristors. The photons are because the company wants to use optical interconnects in the system, built using silicon photonics technology. With silicon photonics, photons are generated on, and travel through, “circuits” etched onto silicon chips, enabling conventional chip manufacturing to construct optical parts. This allows the parts of the system using photons to be tightly integrated with the parts using electrons.

The memristor story has proved to be even more fascinating than I thought in 2008 and I was already as fascinated as could be, or so I thought.

Infusing solar cells with beauty

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There is a bit of a theme emerging (if two news items some six months apart can be considered a theme) with scientists now trying to make solar cells or solar panels (as per my July 3, 2013 posting) objects of beauty. The latest project is from the University of Michigan according to a March 4, 2014 news item on ScienceDaily,

Colorful, see-through solar cells invented at the University of Michigan could one day be used to make stained-glass windows, decorations and even shades that turn the sun’s energy into electricity.

The cells, believed to be the first semi-transparent, colored photovoltaics, have the potential to vastly broaden the use of the energy source, says Jay Guo, a professor of electrical engineering and computer science, mechanical engineering, and macromolecular science and engineering at U-M. Guo is lead author of a paper about the work newly published online in Scientific Reports.

Here’s a video (from the University of Michigan) where Jay Guo describes his work,

For those who are too impatient to watch the video, here’s some of what was discussed along with additional technical detail from a March 3, 2014 University of Michigan news release, which originated the news item,

“I think this offers a very different way of utilizing solar technology rather than concentrating it in a small area,” he said. “Today, solar panels are black and the only place you can put them on a building is the rooftop. And the rooftop of a typical high-rise is so tiny.

“We think we can make solar panels more beautiful—any color a designer wants. And we can vastly deploy these panels, even indoors.”

Guo envisions them on the sides of buildings, as energy-harvesting billboards and as window shades—a thin layer on homes and cities. Such an approach, he says, could be especially attractive in densely populated cities.

In a palm-sized American flag slide, the team demonstrated the technology.

“All the red stripes, the blue background and so on—they are all working solar cells,” Guo said.

The Stars and Stripes achieved 2 percent efficiency. A meter-square panel could generate enough electricity to power fluorescent light bulbs and small electronic gadgets, Guo says. State-of-the art organic cells in research labs are roughly 10 percent efficient.

The researchers are working to improve their numbers with new materials, but there will always be a tradeoff between beauty and utility in this case. Traditional black solar cells absorb all wavelengths of visible light. Guo’s cells are designed to transmit, or—in other versions—reflect certain colors, so by nature they’re kicking energy from those wavelengths back out to our eyes rather than converting it to electricity.

Unlike other color solar cells, Guo’s don’t rely on dyes or microstructures that can blur the image behind them. The cells are mechanically structured to transmit certain light wavelengths. To get different colors, they varied the thickness of the semiconductor layer of amorphous silicon in the cells. The blue regions are six nanometers thick while the red is 31 (the team also made green, but that color isn’t in the flag).

Amorphous silicon is commonly used in screens on cell phones, laptops and large LCD screens, in addition to solar cells. They sandwiched an ultrathin sheet of it between two semi-transparent electrodes that could let light in and also carry away the electrical current.

One of these so-called charge transport layers is made of an organic material. This hybrid structure, a combination of both organic and inorganic components, lets the researchers make cells that are 10 times thinner than traditional amorphous silicon solar cells. The organic layer replaces a thick ‘doped’ region that would typically controls the flow of electricity.

The ultrathin, hybrid design helps the cells hold their color and leads to a nearly 100 percent quantum efficiency. Quantum efficiency is different from overall efficiency. It refers to the percentage of light particles the device catches that lead to electrical current in that charge transport layer. Solar cells can leak current after this point, but researchers strive for a high number.

The cells’ hues don’t change based on viewing angle, which is important for several reasons. It means manufacturers could lock in color for precise pictures or patterns. It’s also a sign that the devices are soaking up the same amount of light regardless of where the sun is in the sky. Conventional solar panels pivot across the day to track rays.

“Solar energy is essentially inexhaustible, and it’s the only energy source that can sustain us long-term,” Guo said. “We have to figure out how to use as much of it as we can.”

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

Decorative power generating panels creating angle insensitive transmissive colors by Jae Yong Lee, Kyu-Tae Lee, Sungyong Seo, & L. Jay Guo. Scientific Reports 4, Article number: 4192 doi:10.1038/srep04192 Published 28 February 2014

This paper is open access.