KI Introduces the World's First Carbon-Negative Chair Made with AIrCarbon

Two childhood friends spent a decade, beginning in college, figuring out how to cheaply make plastic from carbon that's been captured from the atmosphere.

(Photo: Dan MacMedan, USA TODAY)

Story Highlights
While in college, two friends set out to turn air pollution into plastic
Their decade-long journey has led to an award-winning carbon-based product
They aim to reduce global warming by capturing heat-trapping carbon emissions

A decade ago in his Princeton dorm room, Mark Herrema had an aha moment. He read a newspaper story about the rise in heat-trapping methane emissions from dairy farms and decided to do something about it.

He thought — why not pull the carbon from the air and use it to make stuff? A politics major who also studied chemistry, he teamed up with childhood friend Kenton Kimmel, a biomedical engineering student at Northwestern University. They took odd jobs after graduation to fund their research.

"I was a bellhop and Kenton was a valet," says Herrema, recalling how they worked 14 to 16 hours every day — even holidays — for years to pay their bills and test their ideas in rented lab space.

Industry experts told them it was a fool's errand. For good reason. Scientists had spent decades trying to capture carbon and use it to make plastic but couldn't do it cheaply enough. The two friends cracked the code by developing a ten-times more efficient bio-catalyst, which strips the carbon from a liquefied gas and rearranges it into a long chain plastic molecule.

Mark Herrema shows a container of the plastic pellets that his California-based company, Newlight Technologies, makes from recycled methane gas.(Photo: Dan MacMedan, USA TODAY)

The result? Today, the 31-year-old co-founders of California-based Newlight Technologies have two factories that take methane captured from dairy farms and use it to make AirCarbon — plastic that will soon appear in the form of chairs, food containers and automotive parts. Coming next year: cellphone cases for Virgin Mobile.

"You'll be able to hold carbon in your hand," Herrema says of the products, which an independent lab says remove more carbon from the atmosphere than their manufacturing emits. By replacing oil-based plastics, he says he wants to help reduce global warming: "We actually want to change the world."

"This will be a paradigm shift in our industry," says Dick Resch, CEO of furniture maker KI, saying AirCarbon will produce the first carbon-negative furniture. KI, which has backed Newlight for eight years and holds exclusive industry rights to its product, plans next year to sell AirCarbon chairs and eventually other products.

"I wish I had been smart enough to figure this out," says William Dowd, former global director of industrial biotech research and development at Dow Chemical. He says venture capitalists asked him to look at Newlight's work, but he initially demurred, doubting it would break ground. "I was astounded by what they were able to do."

STORY: How technology can halt climate change

Dowd, who is not a Newlight investor, says AirCarbon closely resembles polypropylene and could be a cheaper alternative. He doubts it will do much to reduce global warming, citing the enormity of greenhouse gas emissions from power plants alone.

"It can't be a significant contributor to solving the (climate) problem," agrees Harvard physicist David Keith, adding the supply chain isn't big enough to absorb the 15-plus tons of carbon dioxide emitted per capita each year in the United States. Keith started Calgary-based Carbon Engineering, co-funded by Bill Gates, to capture carbon at industrial scale and use it to make low-carbon fuel.

Still, "it's a step in the right direction," says Brent Ehrlich, products editor of BuildingGreen, a company that studies the construction industry. Ehrlich says AirCarbon could replace a lot of oil-based plastic, adding: "It could potentially add up."

Herrema says his creation is much more than "a drop in the bucket" and is just starting to take off. AirCarbon was chosen as "bio-material of the year" by the 2013 International Conference on Bio-based Plastics and Composites.

 

The winners of the innovation award have been elected by the participants of the conference.

Though their journey had many "tough" months, Herrema says he and Kimmel had enough naivete to believe they'd succeed. "We always felt," he says, "that a breakthrough was just around the corner." 

KI introduces the world's first carbon-negative chair made with AirCarbon™—a revolutionary, paradigm-shifting thermoplastic developed by California-based Newlight Technologies. Newlight's patented manufacturing technology captures carbon that would otherwise be in the air and converts it into AirCarbon. KI will be the exclusive provider of AirCarbon in the contract furniture industry. "By using carbon that would otherwise be in the air we are breathing right now, AirCarbon turns everyday goods into products that actually improve the environment," said Mark Herrema, CEO, Newlight. "Combined with a cost profile that is more favorable than oil-based plastics, AirCarbon has the potential to change the world." Upon completion of lifecycle analysis and environmental testing in early 2014, KI will begin introducing AirCarbon into some of its most successful product lines, including the Strive and Grazie seating collections.

ORIGINAL: USA Today

Stretchy battery drawn to three times its size

ORIGINAL: BBC

By Jason Palmer Science and technology reporter, BBC News

The team tested their battery 

by stretching it 300% while 

it powered an LED lamp

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Researchers have demonstrated a flat, "stretchy" battery that can be pulled to three times its size without a loss in performance.

While flexible and stretchable electronics have been on the rise, powering them with equally stretchy energy sources has been problematic.

The new idea in Nature Communications uses small "islands" of energy-storing materials dotted on a stretchy polymer.

The study also suggests the batteries can be recharged wirelessly.

In a sense, the battery is a latecomer to the push toward flexible, stretchable electronics. A number of applications have been envisioned for flexible devices, from implantable health monitors to roll-up displays.

But consumer products that fit the bendy, stretchy description are still very few - in part, because there have been no equally stretchy, rechargeable power sources for them.

"Batteries are particularly challenging because, unlike electronics, it's difficult to scale down their dimensions without significantly reducing performance," said senior author of the study John Rogers of the University of Illinois at Urbana-Champaign. S for stretch

"We have explored various methods, ranging from radio frequency energy harvesting to solar power," he told BBC News.

In recent years, Prof Rogers worked with colleagues at Northwestern University, focusing on stretchy electronics of various sorts made using what they termed a "pop-up" architecture. The idea uses tiny, widely spaced tiny circuit elements embedded within a stretchy polymer and connected with wires that "popped up" as the polymer was stretched.
The new work hinges on "self-similar", serpentine wires between the battery elements

But batteries do not lend themselves to this idea; traditionally they are much larger than other circuit elements. They could be made from smaller elements wired together, but to create a small battery with sufficient power, the elements must be spaced more closely than those of the pop-up circuits.

The team's new idea was to use "serpentine" connections - wires that loop back on themselves in a repeating S shape, with that string of loops itself looped into an S shape.

Stretching out the polymer in which the tiny solar cells were embedded first stretches out the larger S; as it is stretched further, the smaller turns straighten - but do not become taut, even as the polymer was stretched to three times its normal size.

The team says the stretchy battery can be charged "inductively" - that is, wirelessly over a short distance. Prof Rogers said that the uses for such batteries and the stretchy circuits they power were myriad.

"The most important applications will be those that involve devices integrated with the outside of the body, on the skin, for health, wellness and performance monitoring," he explained.

However, the prototype batteries described in the paper were only run through 20 charge/discharge cycles, and Prof Rogers said that "additional development efforts to improve the lifetime will be required for commercialisation".

Bioinspired Fibers Change Color when Stretched

ORIGINAL: Wyss Institute

January 28, 2013

The so-called "bastard hogberry," shown here floating in water (which changes its apparent color), has inspired a new type of photonic fiber. (Image courtesy of Peter Vukusic.)

Color-tunable photonic fibers mimic the fruit of the "bastard hogberry" plant

A team of materials scientists at Harvard University and the University of Exeter, UK, have invented a new fiber that changes color when stretched. Inspired by nature, the researchers identified and replicated the unique structural elements that create the bright iridescent blue color of a tropical plant's fruit.

The multilayered fiber, described today in the journal Advanced Materials, could lend itself to the creation of smart fabrics that visibly react to heat or pressure.

"Our new fiber is based on a structure we found in nature, and through clever engineering we've taken its capabilities a step further," says lead author Mathias Kolle, a postdoctoral fellow at the Harvard School of Engineering and Applied Sciences (SEAS). "The plant, of course, cannot change color. By combining its structure with an elastic material, however, we've created an artificial version that passes through a full rainbow of colors as it's stretched."

The photonic fibers are made by wrapping multiple layers of polymer around a glass core, which is later etched away. The thickness of the layers determines the apparent color of the fiber, which can range across the entire visible spectrum of light. (Image courtesy of Mathias Kolle.)

Since the evolution of the first eye on Earth more than 500 million years ago, the success of many organisms has relied upon the way they interact with light and color, making them useful models for the creation of new materials. For seeds and fruit in particular, bright color is thought to have evolved to attract the agents of seed dispersal, especially birds.

The fruit of the South American tropical plant, Margaritaria nobilis, commonly called "bastard hogberry," is an intriguing example of this adaptation. The ultra-bright blue fruit, which is low in nutritious content, mimics a more fleshy and nutritious competitor. Deceived birds eat the fruit and ultimately release its seeds over a wide geographic area.

Zooming in on the structure of the hogberry fruit, multiple scales of repeating architecture become clear. (Image courtesy of Mathias Kolle.)

"The fruit of this bastard hogberry plant was scientifically delightful to pick," says principal investigator Peter Vukusic, Associate Professor in Natural Photonics at the University of Exeter. "The light-manipulating architecture its surface layer presents, which has evolved to serve a specific biological function, has inspired an extremely useful and interesting technological design."

Vukusic and his collaborators at Harvard studied the structural origin of the seed's vibrant color. They discovered that the upper cells in the seed's skin contain a curved, repeating pattern, which creates color through the interference of light waves. (A similar mechanism is responsible for the bright colors of soap bubbles.) The team's analysis revealed that multiple layers of cells in the seed coat are each made up of a cylindrically layered architecture with high regularity on the nano- scale.

The researchers at Harvard developed a unique method of producing the photonic fibers; they believe it can be scaled up for industrial fabrication. (Image courtesy of Mathias Kolle.)

The team replicated the key structural elements of the fruit to create flexible, stretchable and color-changing photonic fibers using an innovative roll-up mechanism perfected in the Harvard laboratories.

"For our artificial structure, we cut down the complexity of the fruit to just its key elements," explains Kolle. "We use very thin fibers and wrap a polymer bilayer around them. That gives us the refractive index contrast, the right number of layers, and the curved, cylindrical cross-section that we need to produce these vivid colors."

The researchers say that the process could be scaled up and developed to suit industrial production.

"Our fiber-rolling technique allows the use of a wide range of materials, especially elastic ones, with the color-tuning range exceeding by an order of magnitude anything that has been reported for thermally drawn fibers," says coauthor Joanna Aizenberg, Amy Smith Berylson Professor of Materials Science at Harvard SEAS, and Kolle's adviser. Aizenberg is also Director of the Kavli Institute for Bionano Science and Technology at Harvard and a Core Faculty Member at the Wyss Institute for Biologically Inspired Engineering at Harvard.

The fibers' superior mechanical properties, combined with their demonstrated color brilliance and tunability, make them very versatile. For instance, the fibers can be wound to coat complex shapes. Because the fibers change color under strain, the technology could lend itself to smart sports textiles that change color in areas of muscle tension, or that sense when an object is placed under strain as a result of heat.

Additional coauthors included Alfred Lethbridge at the University of Exeter, Moritz Kreysing at Ludwig Maximilians University (Germany), and Jeremy B. Baumberg, Professor of Nanophotonics at the University of Cambridge (UK).

This research was supported by the U.S. Air Force Office of Scientific Research Multidisciplinary University Research Initiative, by the UK Engineering and Physical Sciences Research Council, and through a postdoctoral research fellowship from the Alexander von Humboldt Foundation. The researchers also benefited from facilities at the Harvard Center for Nanoscale Systems, which is part of the National Nanotechnology Infrastructure Network supported by the U.S. National Science Foundation. The Wyss Institute for Biologically Inspired Engineering at Harvard also contributed to this research.

CONTACT: Caroline Perry, (617) 496-1351

Breaking the bacteria barrier

ORIGINAL: IBM

The Research Team (from left to right): Dr James L. Hedrick, IBM Research, Dr Yi-Yan Yang, IBN Group Leader, Dr Shaoqiong Liu, IBN Research Scientist, Dr Jeremy Tan, IBN Research Scientist and Li Yan, IBN PhD Candidate.

Bacterial biofilms appearing on the skin and on medical devices and household surfaces are difficult to treat and demonstrate high resistance to antibiotics. Antimicrobial hydrogels developed by IBM Research and the Institute for Bioengineering and Nanotechnology demonstrate 100% efficiency in destruction of these biofilms, with application potential for catheter and medical device coatings, implants, skin and everyday surfaces.

New hydrogel born from semiconductor research may help save lives

We are obsessed with cleanliness. From anti-bacterial cart wipes at the supermarket to individual sized packages of wipes and gels that we can carry in a pocket or a purse - you'd think we were winning in the war against germs.

But in hospitals, clinics and other medical facilities, the potential for infection still exists. Despite advanced sterilization and aseptic techniques, infections associated with medical devices and surfaces have not been eradicated, thanks to the increase in drug-resistant bacteria.

According to the CDC, antibiotic drug resistance in the U.S. costs an estimated $20 billion a year in healthcare costs as well as 8 million additional days spent in the hospital[1]. And hospital-acquired infections are among the top five leading causes of death in the United States and account for up to $11 billion in healthcare spending each year[2].

And while personal anti-bacterial products exist on the market today in the form of the aforementioned hand gels and wipes, these products target very common germs and most contain ethanol as a key ingredient. Ethanol evaporates after a very short time after application and does not provide long-lasting protection.

Cleaning products that effectively destroy bacteria on surfaces, including alcohol and bleach, also break down and/or evaporate after a short period of time and are not transferrable for human application based on their toxicity.

Now imagine a long-lasting substance that is biocompatible and non-toxic, but also biodegradable. A substance that destroys specific types of bacteria but leaves healthy skin and cells alone – one that could be applied to medical facility surfaces, surgical and diagnostic instruments, and even – one day - medical implants.

IBM Research, in association with the Institute of Bioengineering and Nanotechnology in Singapore have taken a first step towards that future with the development of an antimicrobial hydrogel that can break through diseased biofilms and eradicate drug-resistant bacteria upon contact.

“We were driven to develop a more effective therapy against superbugs due to the lethal threat of infection by these rapidly mutating microbes and the lack of novel antimicrobial drugs to fight them. Using the inexpensive and versatile polymer materials that we have developed jointly with IBM, we can now launch a nimble, multi-pronged attack on drug-resistant biofilms which would help to improve medical and health outcomes.”. Dr Yi-Yan Yang, Group Leader, Institute of Bioengineering and Nanotechnology, Singapore

It began with computer chips

The IBM nanomedicine polymer program began in IBM Research labs only four years ago with the mission to improve human health.

The program itself stems from decades of materials development traditionally used for semiconductor technologies. In earlier chip development research, IBM researchers identified specific materials that, when chained together, produced an electrostatic charge that allows microscopic etching on a wafer to be done at a much smaller scale.

This newfound knowledge that characterization of materials could be manipulated at the atomic level to control their movement inspired the team to see what else they could do with these new kinds of polymer structures. They started with methicillin-resistant Staphylococcus aureus (MRSA).

The outcome of that experiment was the creation of what are now playfully known as "ninja polymers" – sticky nanostructures that move quickly to target infected cells in the body, destroy the harmful content inside, and can then disappear by biodegrading without causing damaging side effects or accumulating in the organs. As a bonus, all of this occurs without damaging healthy cells in the area.

The next step was to figure out how to apply this new capability to other applications to help fight harmful bacteria.

On the left is a mature and healthy MRSA biofilm. After the hydrogel is applied, the biofilm is destroyed as seen on the right. Photo Credit: IBN

Zipping molecules and zapping bacteria

Through the precise tailoring of polymers, researchers were able to create macromolecules - molecular structures containing a large number of atoms - which combine water solubility, a positive charge, and biodegradability. When mixed with water and heated to normal body temperature, the polymers self-assemble, swelling into a synthetic gel that is easy to manipulate.

“This is a fundamentally different approach to fighting drug-resistant biofilms. When compared to capabilities of modern-day antibiotics and hydrogels, this new technology carries immense potential. This new technology is appearing at a crucial time as traditional chemical and biological techniques for dealing with drug-resistant bacteria and infectious diseases are increasingly problematic.”. James Hedrick, Advanced Organic Materials Scientist, IBM Research

This capability stems from internal reactions that create a molecular "zipper" effect. Similar to how zipper teeth link together, the short segments on the new polymers interlock, thickening the water-based solution into moldable and highly malleable hydrogels.

When applied to contaminated surfaces, the hydrogel's positive charge attracts negatively charged microbial membranes, like stars and planets being pulled into a black hole. However, unlike other antimicrobials that target the internal machinery of bacteria to try to prevent it from replicating, this hydrogel destroys the bacteria by rupturing the bacteria’s membrane, rendering it completely unable to regenerate or spread.

The hydrogel developed by the team is comprised of more than 90 percent water, making it easy to handle and apply to surfaces. It also makes it potentially viable for eventual inclusion in applications like creams or injectable therapeutics for wound healing, implant and catheter coatings, skin infections or even orifice barriers. It is the first-ever to be biodegradable, biocompatible and non-toxic, potentially making it an ideal tool to combat serious health hazards facing hospital workers, visitors and patients.

By preventing infections before they happen, doctors, hospitals, patients and healthcare providers may one day all benefit from improved medical outcomes and lower healthcare costs. This jointly developed hydrogel may be a key that helps open that door to the future.

Explore this topic

IBM Research produces staph-killing polymers that leave healthy cells alone

Research originally published in the Angewandte Chemie International Edition of the Gesellschaft Deutscher Chemiker

View more hydrogel images and videos

Meet the researchers

Dan Coady

Polymer Chemist, 

IBM Research - Almaden

Amanda Engler

Post Doctoral Researcher, 

IBM Research - Almaden

James Hedrick

Advanced Organic Materials, 

IBM Research - Almaden

1 U.S. Dept. of Health and Human Services, Agency for Healthcare Research and Quality: Hospital-acquired infections dramatically increase trauma patients' risk of in-hospital death and hospital stay

2 Centers for Disease Control and Prevention: Antimicrobial Resistance Posing Growing Health Threat

Nanoparticles deliver cargo inside mitochondria

ORIGINAL: Foresight Institute

Shanta Dhar, right, an assistant professor of chemistry in the UGA Franklin College of Arts and Sciences, and doctoral student Sean Marrache have fabricated nanoparticles that boost the effectiveness of drugs by delivering them to the mitochondria of cells (credit: University of Georgia).

Targeted drug delivery is one of the most important contributions of current and near-term nanotechnology to medicine. New research shows that specifically targeting one component of the cell makes nanoparticle-mediated drug delivery much more effective for a variety of applications. A hat tip to KurzweilAI.net for reprinting this University of Georgia news release “UGA researchers boost efficacy of drugs by using nanoparticles to target ‘powerhouse of cells’“:

Nanoparticles have shown great promise in the targeted delivery of drugs to cells, but researchers at the University of Georgia have refined the drug delivery process further by using nanoparticles to deliver drugs to a specific organelle within cells.

By targeting mitochondria, often called “the powerhouse of cells,” the researchers increased the effectiveness of mitochondria-acting therapeutics used to treat cancer, Alzheimer’s disease and obesity in studies conducted with cultured cells.

“The mitochondrion is a complex organelle that is very difficult to reach, but these nanoparticles are engineered so that they do the right job in the right place,” said senior author Shanta Dhar, an assistant professor of chemistry in the UGA Franklin College of Arts and Sciences.

Dhar and her co-author, doctoral student Sean Marrache, used a biodegradable, FDA-approved polymer to fabricate their nanoparticles and then used the particles to encapsulate and test drugs that treat a variety of conditions. Their results were published this week in early edition of the journal Proceedings of the National Academy of Sciences [abstract].

To test the effectiveness of their drug targeting system against cancer, they encapsulated the drug lonidamine, which works by inhibiting energy production in the mitochondria, and, separately, a form of the antioxidant vitamin E. They then treated cultured cancer cells and found that mitochondrial targeting increased the effectiveness of the drugs by more than 100 times when compared to the drugs alone and by five times when compared to the delivery of drugs with nanoparticles that target the outside of cells.

Similarly, the compound curcumin has shown promise in inhibiting formation of the amyloid plaques that are a hallmark of Alzheimer’s disease, but it quickly degrades in the presence of light and is broken down rapidly by the body. By encapsulating curcumin in the mitochondria-targeting nanoparticles, however, the researchers were able to restore the ability of brain cells in culture to survive despite the presence of a compound that encourages plaque formation. Nearly 100 percent of the cells treated with the mitochondria-targeting nanoparticles survived in the presence of the plaque-inducing compound, compared to 67 percent of cells treated with free curcumin and 70 percent of cells treated with nanoparticles that target the outside of cells.

Finally, the researchers encapsulated the obesity drug 2,4-DNP—which works by making energy production in the mitochondria less efficient—in their nanoparticles and found that it reduced the production of fat by cultured cells known as preadipocytes by 67 percent compared to cells treated with the drug alone and by 61 percent of cells treated with nanoparticles that target the outside of cells.

“A lot of diseases are associated with dysfunctional mitochondria, but many of the drugs that act on the mitochondria can’t get there,” Marrache said. “Rather than try to alter the drugs, which can reduce their effectiveness, we encapsulate them in these nanoparticles and precisely deliver them to the mitochondria.”

Dhar said that getting drugs to the mitochondria is no simple feat. Upon entering cells, nanoparticles enter a sorting center known as the endosome. The first thing Dhar and Marrache had to demonstrate was that the nanoparticles escape from the endosome and don’t end up in the cells’ disposal center, the lysosome.

The mitochondria itself is protected by two membranes separated by an interstitial space. The outer membrane only permits molecules of a certain size to pass through, while the inner membrane only permits molecules of a given range of charges to pass. The researchers constructed a library of nanoparticles and tested them until they identified the optimum size range—64 to 80 nanometers, or approximately 1,000 times finer than the width of a human hair—and an optimum surface charge, plus 34 millivolts.

Dhar notes the components they used to create the nanoparticles are FDA approved and that their methods are highly reproducible and therefore have the potential to be translated into clinical settings. The researchers are currently testing their targeted delivery system in rodents and say that preliminary results are promising.

“Mitochondrial dysfunctions cause many disorders in humans,” Dhar said, ” so there are several potential applications for this delivery system.”

Subject to the usual caveat that these nanoparticles are still in an early stage of testing, having been tested only in cell culture, it is remarkable that such effective targeting to reach the matrix of the mitochondria was achieved by the relatively crude strategy of optimizing only particle size and surface charge through engineering polymer composition. So success was achieved through clever application of biological knowledge more than through sophisticated atomically precise construction. It will be fascinating to watch the evolution of this technology as ever more sophisticated construction leads to increasing effectiveness. While we are waiting, this targeting of drug delivery to mitochondria is likely to be especially helpful because so many pathologies seem rooted in imperfections and consequences of the symbiosis that led to eukaryotic cells, and all complex life on Earth, nearly two billion years ago.

—James Lewis, PhD

Super-sponge polymer turns oil spill into floating gel

ORIGINAL: New Scientist

Following the Deepwater Horizon disaster, many new ways of cleaning up oil have been proposed. Now Mike Chung from Pennsylvania State University in University Park and colleagues have developed a novel approach using a super-absorbent material that turns an oil slick into a gel.

The material is a kind of polymer called a polyolefin, and can quickly soak up crude oil without mopping up water, absorbing up to 45 times its own weight (see video above). The gel that forms can then be removed and shipped to a refinery, where about 19 litres of oil can be recovered from a pound of the material. This is an advantage over existing absorbents, which become industrial waste after use.

According to Chung, the material's low cost makes it a viable solution. "Polyolefin products are inexpensive, with a large production capability around the world," he says.

If you enjoyed this post, watch a forked boom scoop up an oil spill or see a micro-submarine clean up motor oil.

IBM researchers unleash plastic 'ninjas' to fight deadly bacteria

ORIGINAL: IBMLabs

Having discovered that materials could be manipulated at the atomic level to control their movement, IBM researchers used this knowledge to create staph-killing 'ninja polymers' that leave healthy cells alone. They move quickly to target infected cells in the body, destroy the harmful content inside, and then disappear from the body by biodegrading without damaging side effects or accumulating in the organs.

Metafluids: German researchers realize new material class

ORIGINAL: Phys.org

May 8, 2012

Pentamode metamaterials almost behave like fluids. Their manufacture opens new possibilities in transformation acoustics. Credit: Source: CFN, KIT

A research team lead by Professor Martin Wegener at the Karlsruhe Institute of Technology has succeeded in realizing a new material class through the manufacturing of a stable crystalline metafluid, a pentamode metamaterial. Using new nanostructuring methods, these materials can now be realized for the first time with any conceivable mechanical properties. The researchers will present their results in the cover story of the May issue of Applied Physics Letters.

The Rubicon was crossed, so to speak, at the DFG Center for Functional Nanostructures (CFN) and at the Institute of Applied Physics (AP) in Karlsruhe during the past few months. Eventually, numerous three-dimensional transformation acoustics ideas, for example inaudibility cloaks, acoustic prisms or new loudspeaker concepts, could become reality in the near future.

So far, pentamodes, proposed in 1995 by Graeme Milton and Andrej Cherkaev, have been purely theoretical: The mechanical behavior of materials such as gold or water is expressed in terms of compression and shear parameters. Whereas the phenomenon that water, for example, can hardly be compressed in a cylinder is described through the compression parameter, the fact that it can be stirred in all directions using a spoon is expressed through the shear parameters.

The word penta is derived from ancient Greek and means "five". In the case of water, the five shear parameters equal zero, and only one parameter, compression, differs from that value. In terms of parameters, the ideal state of a pentamode metamaterial corresponds to the state of water, which is why that material is referred to as a metafluid. Theoretically, any conceivable mechanical properties whatsoever can be obtained by varying the relevant parameters.

"Realizing a pentamode metamaterial is about as difficult as trying to build a scaffold from pins that must not touch but at their tips," first author Dr. Muamer Kadic explains. "The Karlsruhe prototype has been manufactured from a polymer. The mechanical behavior of the material is determined by the acuteness and length of the individual "sugar loaves". On the one hand, we must be capable of designing small sugar loaves in the nanometer range and connect them to one another at the right angle. On the other hand, the entire structure must eventually become as large as possible. Since the material itself contributes only little more than one percent to the respective volume, the composite obtained is extremely light.

"To obtain similar 3D results, as in transformation optics, transformation acoustics is exclusively dependent on metamaterials. In view of this, this first manufacture of our pentamode metamaterial is a quite significant success," adds Tiemo Bückmann, who is about to receive his diploma at the Institute of Applied Physics and is responsible for realizing the structures of the new material by means of dip-in laser writing, a method that has been derived from direct laser writing developed by the Nanoscribe company.

In recent years, a Professor at the Institute of Applied Physics and CFN coordinator, Martin Wegener and his collaborators, have developed direct laser writing and, based on that method, established optical lithography of three-dimensional nanostructures. Numerous achievements of Wegener's group in transformation optics e.g., the first three-dimensional cloak of invisibility in the range of visible light have been due to that technique.

Provided by Helmholtz Association of German Research Centres

Scientists develop 2-component polymer scaffolds for controlled 3-D cell culture

ORIGINAL: Phys.org
April 6, 2011

This is a cell in the two-component polymer scaffold. The photo composition is based on a scanning electron microscopy and laser scanning microscopy. Credit: Image: CFN

At Karlsruhe Institute of Technology (KIT), researchers of the DFG Center for Functional Nanostructures (CFN) succeeded in specifically cultivating cells on three-dimensional structures. The fascinating thing is that the cells are offered small "holds" in the micrometer range on the scaffold, to which they can adhere. Adhesion is possible to these holds only, not to the remaining structure. For the first time, cell adhesion and, hence, cell shape are influenced precisely in three dimensions. The team headed by Professor Martin Bastmeyer thus has achieved big progress in the field of biomaterial engineering.

So far, several approaches have been used to cell culture in three-dimensional environments which are mostly produced from agarose, collagen fibers or matrigel. They are to simulate the flexible three-dimensional reality in which the cells act normally and, hence, allow for more realistic experiments than those using cell cultures in "two-dimensional Petri dishes". All approaches used so far have one common feature: They are mostly heterogeneous with random pore sizes. They have hardly been characterized structurally and biochemically.

It was the objective of the group under the direction of Bastmeyer to develop defined three-dimensional growth substrates for the cell culture. The cells are to adhere at certain points only rather than randomly. In this way, parameters, such as the cell shape, cell volume, intercellular force development, or cellular differentiation can be determined systematically as a function of the external geometry of the surroundings. These findings are needed for the later specific larger-scale production of three-dimensional growth environments for tissue cultures required in regenerative medicine, for instance.

This image shows laser-scanning microscopy (LSM) of the cell in the two-component polymer scaffold. The cytoskeleton of the cell is colored green, parts of the two-component polymer scaffold are colored white, the "cell holds" are colored red. Credit: Image: CFN

This objective was reached by means of a special polymer scaffold. The scaffold consists of a flexible, protein-repellent polymer with small box-shaped holds made of a protein-binding material. For scaffold construction, the scientists used the Direct Laser Writing Method (DLS) developed by the physicists Professor Martin Wegener and Professor Georg von Freymann at CFN. By means of this process, the protein-repellent structure was fabricated. It consists of 25 µm high pillars that are connected by thin bars at various heights. In a second lithography step, the holds were placed exactly in the middle of the bars. With the help of a solution of adhesion proteins, the proteins only bind to these small holds. Within two hours, individual cells colonize the scaffolds and adhere to the given adhesion points only.

For the first time, the scientists of CFN, Karlsruhe, succeeded in producing suitable materials, in which the growth of individual cells can be controlled and manipulated specifically in three dimensions. This is an important step towards the general understanding of how the natural three-dimensional environment in the tissue influences the behavior of cells.

More information: Klein, F., Richter, B., Striebel, T., Franz, C. M., Freymann, G. v., Wegener, M., and Bastmeyer, M., Two-Component Polymer Scaffolds for Controlled Three-dimensional Cell Culture. Advanced Materials, Volume 23, Issue 11, pages 1341, March 18, 2011, DOI:10.1002/adma.201004060

Provided by Helmholtz Association of German Research Centres (news : web)