Self-Healing Plastic 'Skin' Points Way to New Prosthetics

by Tim Wogan on 11 November 2012, 1:00 PM | 0 Comments

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Cutting edge. After it was divided with a scalpel, a new polymer was able to heal itself, restoring most of its mechanical and electrical properties in 15 seconds.

Credit: Benjamin Tee and Chao Wang

Human skin is a special material: It needs to be flexible, so that it doesn't crack every time a user clenches his fist. It needs to be sensitive to stimuli like touch and pressure—which are measured as electrical signals, so it needs to conduct electricity. Crucially, if it's to survive the wear and tear it's put through every day, it needs to be able to repair itself. Now, researchers in California may have designed a synthetic version—a flexible, electrically conductive, self-healing polymer.
The result is part of a decadelong miniboom in "epidermal electronics"—the production of circuits thin and flexible enough to be attached to skin (for use as wearable heart rate monitors, for example) or to provide skinlike touch sensitivity to prosthetic limbs. The problem is that silicon, the base material of the electronics industry, is brittle. So various research groups have investigated different ways to produce flexible electronic sensors.
Chemists, meanwhile, have become increasingly interested in "self-healing" polymers. This sounds like science fiction, but several research groups have produced plastics that can join their cut edges together when scientists heat them, shine a light on them, or even just hold the cut edges together. In 2008, researchers at ESPCI ParisTech showed that a specially designed rubber compound could recover its mechanical properties after being broken and healed repeatedly.

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Chemical engineer Zhenan Bao of Stanford University in Palo Alto, California, and her team combined these two concepts and explored the potential of self-healing polymers in epidermal electronics. However, all the self-healing polymers demonstrated to date had had very low bulk electrical conductivities and would have been little use in electrical sensors. Writing in Nature Nanotechnology, the researchers detail how they increased the conductivity of a self-healing polymer by incorporating nickel atoms, allowing electrons to "jump" between the metal atoms. The polymer is sensitive to applied forces like pressure and torsion (twisting) because such forces alter the distance between the nickel atoms, affecting the difficulty the electrons have jumping from one to the other and changing the electrical resistance of the polymer.
To demonstrate that both the mechanical and the electrical properties of the material could be repeatedly restored to their original values after the material had been damaged and healed, the researchers cut the polymer completely through with a scalpel. After pressing the cut edges together gently for 15 seconds, the researchers found the sample went on to regain 98% of its original conductivity. And crucially, just like the ESPCI group's rubber compound, the Stanford team's polymer could be cut and healed over and over again.
"I think it's kind of a breakthrough," says John J. Boland, a chemist at the CRANN nanoscience institute at Trinity College Dublin. "It's the first time that we've seen this combination of both mechanical and electrical self-healing." He is, however, skeptical about one point: "With a scalpel you can very precisely cut the material without inducing significant local mechanical deformation around the wound." Failure due to mechanical tension, however, could stretch the material, producing significant scarring and preventing complete self-healing, he suspects.
Now, Bao and her fellow researchers are working to make the polymer more like human skin. "I think it will be very interesting if we can make the self-healing skin elastic," she says, "because, while it's currently flexible, it's still not stretchable. That's definitely something we're moving towards for our next-generation self-healing skin."

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The Evidence for LENR

March 29, 2012 / Brad Arnold / 15 comment(s) / Business and Economics, Science and Technology

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“Over 2 decades with over 100 experiments worldwide indicate LENR is real, much greater than chemical…” –Dennis M. Bushnell, Chief Scientist, NASA Langley Research Center Low Energy Nuclear Reaction (LENR) using nickel and hydrogen is a clean, very very cheap, and super abundant new energy technology. It would be fair to say that it is the silver bullet for our current continual energy crisis – and as a consequence sounds too good to be true.
In November of 2009 the US Defense Intelligence Agency (DIA) published Defense Analysis Report DIA 8-0911-003 titled “Technological Forecast: Worldwide Research on Low-Energy Nuclear Reactions Increasing and Gaining Acceptance” ( http://www.lenr-canr.org/acrobat/BarnhartBtechnology.pdf ).
The paper gives a rundown of Low Energy Nuclear Reaction work being done around the world. Among other things it notes: “DIA assesses with high confidence that if LENR can produce nuclear-origin energy at room temperatures, this disruptive technology could revolutionize energy production and storage, since nuclear reactions release millions of times more energy per unit mass than do any known chemical fuel.”
“Energy density many orders of magnitude over chemical.” –Michael A. Nelson, NASA
Here is a detailed description of a LENR generator and formula that was producing energy over unity. In the March of 1994 US government contract F33615-93-C-2326 titled “NASCENT HYDROGEN: AN ENERGY SOURCE” ( www.lenr-canr.org/acrobat/GernertNnascenthyd.pdf ), “Anomalous heat was measured from a reaction of atomic hydrogen in contact with potassium carbonate on a nickel surface.”
This phenomenon (LENR) has been confirmed in hundreds of published scientific papers as is shown by this document titled “Tally of Cold Fusion Papers” ( http://lenr-canr.org/acrobat/RothwellJtallyofcol.pdf ). It gives readers a sense of the scale, variety, and sources of the material available about this subject. It also gives some indication of how much has been published on cold fusion, and where they were published.
Of special note is a PowerPoint presentation by George Miley of the University of Illinois ( https://netfiles.uiuc.edu/mragheb/www/NPRE%20498ES%20Energy%20Storage%20Systems/Nuclear%20Battery%20using%20Clusters%20in%20Nanomaterials.pptx ), who has successfully replicated the LENR “cold fusion” reaction.
In the ebook “Secrets of E-Cat,” (Consulente Energia Publisher, 145 pages, 68 illustrations, Pdf format, 7 €, http://www.consulente-energia.com/cold-fusion-book-secrets-e-cat-by-mario-menichella-secret-ecat-andrea-rossi-focardi-energy-catalyzer.html ) author Mario Menichella says:
“The modern history of cold fusion begins with the premature announcement made in the United States by the two electrochemical Martin Fleischmann and Stanley Pons, who in 1989 convened a press conference…there were numerous attempts to replicate (their) result, but for some years had little success, so that soon the question of cold fusion was labeled by the media and mainstream science as a “hoax.”
Menichella continues, “The probably better experimental work…carried out in Siena since the early Nineties, by a group of physicists composed by Sergio Focardi (University of Bologna), Francesco Piantelli (University of Siena), Roberto Habel (University of Cagliari), but it did not lead to a system capable of generating useful amount of excess energy for normal industrial or domestic applications. In Siena, in fact, the three scientists – using hydrogen and nickel as the two only “ingredients” of the reaction, plus an appropriate amount of heat supplied to the system – managed to get out a double thermal energy than the electrical energy provided in input.”
You may be wondering why the ebook is called “Secrets of E-Cat.” As you can see, LENR (otherwise loosely known as “cold fusion”) is a proven scientific phenomena, but the excess energy from this exothermic reaction was not large enough for normal industrial or domestic applications. In comes Andrea Rossi, the e-cat fusion developer, an Italian inventor who has a Masters Degree in Engineering from Milan University.
To quote the article “ANDREA ROSSI BIOGRAPHY – STORY”
( http://ecatfusion.com/e-cat/andrea-rossi-biography-the-e-cat-fusor-story ):
“In 2007, Andrea Rossi arrived at the very critical point in his research and concentrated his time on his invention. He also hired Sergio Focardi, a physicist from the University of Bologna who is an acknowledged expert in field. The physicist’s work on nickel hydrogen reactions proved to be invaluable…In 2009, Mr. Rossi introduced to the public a process and a device called the E-Catalyst. This is a revolutionary process in energy production and is also called low energy nuclear reactions. It could be a breakthrough invention since it can solve some of the energy problems of our planet.”
I recommend watching the video contained in this article titled “Nobel laureate touts E-Cat cold fusion” (http://pesn.com/2011/06/23/9501856_Nobel_laureate_touts_E-Cat_cold_fusion/ ). Dr. Brian Josephson, winner of the 1973 Nobel Prize in Physics, stars in the video whose stated purpose is to wake up the media to the E-Cat story, which has not been widely reported on in the mainstream media of the English-speaking world.
By the way, here is a article titled “The New Breed of Energy Catalyzers: Ready for Commercialization?” ( http://www.cleantechblog.com/2011/08/the-new-breed-of-energy-catalyzers-ready-for-commercialization.html ), which contains a relatively current survey of all the companies that are trying to bring LENR to commercialization.
The subject of LENR, a clean, very very cheap, and super abundant energy technology, is too deep to comprehensively cover in this limited space. Using only nickel and hydrogen, both very abundant and cheap, in a LENR exothermic reaction, could be a source of almost unlimited energy for humanity, with a cost close to nothing, and no environmental pollution. Hopefully the limited evidence for LENR cited above will go part of the way toward convincing an open minded reader of the validity of this too good to be true energy technology.
“Total replacement of fossil fuels for everything but synthetic organic chemistry.” –Dr. Joseph M. Zawodny, NASA

Engineered particles made to self-assemble like atoms

They could spur new high-tech materials for better optical displays, faster computer chips

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Illustration courtesy of Yufeng Wang and Yu Wang

Scientists have created new kinds of particles, 1/100th the diameter of a human hair, that spontaneously assemble themselves into structures resembling molecules made from atoms.

updated 11/1/2012 6:51:05 PM ET

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Particles engineered to spontaneously self-assemble like atoms forming molecules could give rise to new high-tech materials, leading to better optical displays and faster computer chips, researchers say.

Scientists have crafted the new particles, which are 1/100th the diameter of a human hair, by altering the architecture of colloids, tiny particles suspended in liquids, and which can be found dispersed in everyday items such as paint, milk, glass and porcelain. The work is detailed this week in the journal Nature.
Engineers have been limited in their ability to manipulate these particles into new patterns that would form the building blocks of new materials because colloids stick to one another randomly; in science speak, they lack directional bonds, or bonds that prefer a specific orientation.
In an accompanying essay in the same issue of Nature, Northwestern University's Matthew Jones and Chad Mirkin describe the predicament of trying to make structures from these particles as "trying to assemble a bookcase from parts covered in glue that stick to each other equally well wherever they touch, regardless of their relative orientations," the material scientists wrote. "You would quickly find the task to be extremely challenging, because the components would keep joining together in haphazard configurations, rather than fitting neatly into their intended positions."

Image courtesy of Vinothan N. Manoharan and David J. Pine

These are electron microscope images of "colloidal atoms," micrometer-sized particles with patches that allow bonding only along particular directions. From left to right: particle with one patch (analogous to a hydrogen atom), two, three, four (analogous to a carbon atom), five, six, and seven patches.

To form new, complex molecular structures, chemists use atoms with directional bonds, which are necessary to control self-assembly and maintain structural integrity.
"Chemists have a whole periodic table of atoms to choose from when they synthesize molecules and crystals," study researcher Vinothan Manoharan of Harvard said in a statement. "We wanted to develop a similar 'construction set' for making larger-scale molecules and crystals."
The team created chemically distinct "patches" on the particles' surfaces that could form directional bonds, sticking to other particles in specific patterns to spontaneously form "colloidal molecules" of the researchers' design.

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To ensure the patches interacted with other patches in specific ways, the scientists used single strands of DNA to create "sticky ends" to which particle patches adhered, placing up to seven patches on each particle.
The scientists say they could manipulate these bonds to create colloids of a specific color, size, chemical function or electrical conductivity. This, in turn, could lead to the production of new materials, such as photonic crystals to improve optical displays and boost the speed of computer chips.

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"What this means is we can make particles that attach only at the patches, and then we can program them so only specific kinds of particles attach at those patches," added another researcher involved in the study, David Pine, an NYU physics professor. "This gives us tremendous flexibility to design 3-dimensional structures."