An armorlike arapaima fish scale resists being fractured by a piranha tooth that is slowly pressed into it. In fact, it is the tooth that fails. Credit: Meyers Group: Credit: UCSD Jacobs Sch. of Eng.

If you ever watch cable TV’s River Monsters (and, honestly, who doesn’t!), you might be familiar with a large Amazonian “living fossil” fish that goes by the name arapaima.

The arapaima have a reputation for being one of the few animals in the Amazon that hungry piranha don’t bother. Why? Apparently it is because evolution has draped the arapaima in a flexible skin of “armor” that is effectively impenetrable to the piranhas’ teeth. The fish has “scales,” but there aren’t many other species among fish that come close to the defenses of the arapaima.

Researcher Marc Meyers, an expert on bio-inspirational design and a professor at the Jacobs School of Engineering at University of California, San Diego, knew of this reputation and speculated that if the arapaima are indeed protected from piranhas’ bites, maybe insights from the structure of the arapaima’s scales could provide ideas for engineering new materials, such as flexible ceramics.

(Meyers’ name may be familiar to some. He was one of the stars in one of the episodes of Nova’s “Making Stuff” TV series, in which he discussed the strength of mullosk shells.)

As can be seen in the above video, Meyers, along with his students and colleagues, set up a simple desktop test. They attach an arapaima scale to a soft rubber base (to simulate the fish’s soft muscle and tissue under the scale) and mounted a single piranha tooth in a press. The tooth is then pressed into the scale. In each case, the tooth can partially penetrate the scale, but the tooth cracks before the scale suffers a total fracture.

Credit: Meyers Group; UCSD.

Meyers says in a UC San Diego release that the structure of the scale is combination of a mineralized outer layer with a clever and tough internal design (see diagram from the press release). This tough inner layer has collagen fibers stacked in alternating directions “like a pile of plywood.” He says the mix of materials in the scale is similar to the hard enamel of a tooth deposited over softer dentin.

Implications? Meyers says that the arapaima’s design should serve as bioinspiration for lots of things that need to be both tough and flexible, for example body armor, fuel cells, insulation and aerospace designs.

Some lessons for engineers are from this work are:

• Combine hard and soft materials
• Stack the materials in the underlying layer with different orientations
• Texture is key, and a varying surface provides more capability.

On this last point, Meyers notes that each scale has an exterior that is “corrugated.” According to the story, “the corrugated surface keeps the scales’ thick mineralized surface intact while the fish flexes as it swims. Ceramic surfaces of constant thickness are strained when forced to follow a curved surface. The corrugations allow the scales to ‘be bent more easily without cracking,’ Meyers said.”

Meyers says he will also be studying the scales of another unusual fish, the alligator gar whose scales were reportedly used as arrow tips.

Corrugated texture of arapaima scales. Credit: Meyers Group; UCSD Jacobs Sch. of Eng.

Meyers et al. have written about their studies in the The Journal of the Mechanical Behavior of Biomedical Materials in the paper, “Biological materials: A materials science approach” (doi:10.1016/j.jmbbm.2010.08.005).

Share

The goal of the MGI is to support the creation of new computational tools, software and methods for materials characterization, plus foster the creation of open standards and databases that would make the development of advanced materials occur faster, with less expense and more predictability.

Because of the far-reaching impact the MGI will have on the materials science and engineering community — and the professional societies that support this work — ACerS’ Senior Editor Eileen De Guire interviewed a representative of the Obama administration, Cyrus Wadia, to discuss the administration’s vision of the MGI effort. Wadia is the assistant director for Clean Energy & Materials R&D in the White House Office of Science and Technology Policy in Washington, DC.

This interview was conducted Oct. 17, 2011, at the Materials Science & Technology 2011 Conference in Columbus, Ohio.

Video length: 6 minutes.

Share

I’ve been following the news coverage of the annual Consumer Electronic Show held last week in Las Vegas, and it appears that a lot of writers were underwhelmed by what they saw. Some items, such as large-format OLED television screens and a slew of “smart” TVs, turned heads, but few observers claim to see any huge breakout products.

However, there was one event display that commentators consistently mentioned in positive tones: Corning’s booth where it showcased its glass technologies. In other words, one of the stars of the CES show wasn’t really a consumer product but is enabling technologies in the engineered glass field.

Importantly, Corning used the CES to do a public rollout of what it calls Gorilla Glass 2. From the Corning news release:

Corning Gorilla Glass 2 enables up to a 20 percent reduction in glass thickness, while maintaining the industry-leading damage resistance, toughness, and scratch resistance customers have come to expect from the world’s most widely deployed cover glass. The thinner Gorilla Glass 2 enables slimmer and sleeker devices, brighter images, and greater touch sensitivity. These benefits can provide electronics manufacturers with superior design flexibility as they address consumer demand for increasingly high-performing, touch-sensitive, and durable mobile devices.

James R. Steiner, senior vice president and general manager, Corning Specialty Materials, went on to say that

“[W]e designed this new glass to enable meaningful reduction in thickness without sacrificing the outstanding glass performance for which Gorilla Glass has become highly recognized. This glass, along with Windows operating system innovations from Microsoft, will help deliver exceptional beauty, performance, and toughness for new Windows PCs. You will see this early this year with Windows-based PCs which we expect to be the first in-market laptops designed to leverage the performance of our new second-generation glass.”

Corning also says that product qualification and design implementation for GG2 is underway with various customers, and a number of products containing GG2 are expected “during the coming months.”

GG is pretty ubiquitous, and the release claims that it is “the most widely deployed cover glass, used by more than 30 major brands and designed into more than 575 product models, spanning more than 500 million units worldwide. As one of the company’s fastest growing businesses, Corning Gorilla Glass is expected to reach more than $700 million in 2011 sales, nearly triple 2010 results.”

It’s probably not a coincidence, but Corning posted several new videos during the CES. I had hoped to provide a video specifically about GG2, and one was/is apparently in the works. I received a notice that a new video on GG2 had been posted on YouTube, but by the time I got around to try to take a look at it, it had been taken down by Corning. So, instead of a GG2 video, I am using a new video featuring Peter L. Bocko, Corning Glass Technologies’ CTO, who explains how the company foresees the market and demand for thin glass applications. Some of the new videos are:

• Corning sights & sounds at CES 2012
• Bocko commentary: A thinner display industry
• The fusion process: At the core of Corning’s glass innovations
• Corning Gorilla Glass for seamless, elegant design
• Corning’s ultra-slim flexible glass for roll-to-roll processing

Share

Bre Pretis, CEO of MakerBot demonstrates a rapid prototype manufacturing process for printing objects. Credit: Time.

3D printing is a relatively new but no longer unusual process for materials scientists and engineers. Indeed, researchers have been using it to build and test ideas of prototypes of things such as biomedical scaffolds, casting molds for turbine blades, espresso cups, etc.

While once relatively rare, such printers are starting to seep into the DIY and consumer pipelines, and several companies have received significant financial backing for hardware and software businesses associated with personal 3D printers.

Although the video above demonstrates MakerBots‘ printers (~$1,300) that produce products composed of ABS plastic, there are also systems becoming available that will make products composed of ceramics, glass, metals and even concrete.

This video comes from Time, which also has an interesting new article about a wholly-owned subsidiary within Phillips—Shapeways—that claims to be “the largest marketplace for printable 3D designs.” Shapeways operates as something along the lines of Etsy, serving as a platform for 3D design “stores” that sell downloadable CAD files for use with personal printers. Shapeways makes and sells the aforementioned espresso cups, for example.

Although some of Shapeway’s store owners sell designs for jewelry and toys, others are starting to create more elaborate technical designs. The Time story reports, “On the flip side, there are public interest uses too, as doctors have employed 3D printing to lower medical costs. Mark Frame, an orthopedic surgical trainee at RHSC Glasgow recently used Shapeways and CT-scan information to create a 3D model of a fractured forearm to practice a surgery. Instead of the normal $1,200, the Shapeways model cost just $120. It’s hard to guess what kinds of things will be possible in the future, but aside from hoping to print in gold and mixed materials, Weijmarshausen theorizes that in five or ten years 3D printers will be able to churn out working electronics, such as an iPod.”

Another design marketplace and 3D forum is Thingiverse.

The individual pieces from 3D printers can be used to assemble larger structures. Violin and car body prototypes have been built this way. Proponents says its only a matter of time before it may be possible to create anything from personal body parts to concrete structures to entire buildings. It’s unclear, however, how small-scale innovators are addressing the sintering, tempering or annealing work that would be needed to finish objects composed of ceramic or glass powders.

Regardless, personal 3D printing seems to be rapidly transitioning from a novelty to a serious technique for producing and delivering consumer goods. As Time reports, one big outstanding roadblock may end up in the courts because of the new questions raised concerning intellectual property control over the sale and use of the 3D designs.

Share

Daniel Shechtman’s diffraction pattern was tenfold: turning the picture a tenth of a full circle (36 degrees) results in the same pattern. Credit: Shechtman; Royal Swedish Academy of Sciences.

Daniel Shechtman, while working at NIST alongside other luminaries, such as John Cahn, set the physics and materials science world atwitter (even before Twitter!) in 1984 when Physical Review Letters (doi:10.1103/PhysRevLett.53.1951) published a paper by him, Cahn, Denis Gratias and Ilan Blech reporting the discovery of a material that had a unique diffraction pattern (above) suggestive of a crystalline structure but apparently lacked a regularly ordered and repeating three-dimensional pattern.

The discovery reported was duly attributed to Shechtman. In 1982, he stumbled upon the phenomenon while studying an aluminum-mangnese alloy. The unexpected appearance of ten major dots in each concentric circle in the material’s diffraction pattern initially baffled Shechtman and others because it was unknown in crystallographic guides and seemed to violate the basic rules of crystallography. He followed up the initial data with other experiments that indicated the material had a five-fold symmetry, a characteristic that was thought to be impossible.

Cahn et al.’s contribution to Shechtman’s work was primarily to confirm his findings and conclusions about the existence of what came to be known as quasicrystals.

What Shechtman had discovered, in essence, in the Al-Mn alloy is that the five-fold symmetry creates an aperiodic regular “pattern” or “quasiperiodic” structure. Perhaps the easiest way to wrap one’s thinking around an regular aperiodicity is to look at the work, coincidentally done just several years before Shechtman’s discovery, by mathematicians, such as Roger Penrose, who created special mosaics with a limited number of tiles, a limitation that provides the appearance of some pattern similarities, while creating patterns that never actually repeat (see example, below). A Fibonacci sequence is another familiar example of regular aperiodicity.

Pentagonal aperiodic tiling by Roger Penrose using only two sizes of tiles. Identifying the vertices as atomic positions generates a quasiperiodic structure. Credit: R. Penrose; Royal Swedish Academy of Sciences.

The work of Penrose and others eventually provided Shechtman (and others who joined the investigation of quasicrystals) an explanation of how the material might actually be structured.

Shechtman’s assertions made him an outcast for a few years, but his dogged pursuit of an explanation of his findings eventually put him ahead of other researchers who, as it turns out, had observed similar patterns and data but had too-hastily dismissed the diffractions as being the result of twinned or intermingled crystals.

Background material provided by the Royal Swedish Academy of Sciences reports that hundreds of different types of quasicrystals have now been synthesized and that at least one natural mineral has been found to have that structure. Here is what the Academy says about the uses of quasicrystals:

When trying out different blends of metal, a Swedish company managed to create [a] steel with many surprisingly good characteristics. Analyses of its atomic structure showed that it consists of two different phases: hard steel quasicrystals embedded in a softer kind of steel. The quasicrystals function as a kind of armor. This steel is now used in products such as razor blades and thin needles made specifically for eye surgery.

Despite being very hard, quasicrystals can fracture easily, like glass. Due to their unique atomic structure, they are also bad conductors of heat and electricity, and have non-stick surfaces. Their poor thermal transport properties may make them useful as so-called thermoelectric materials … Today, scientists also experiment with quasicrystals in surface coatings for frying pans, in components for energy-saving light-emitting diodes, and for heat insulation in engines, among other things.

Here’s a great 2010 interview with Shechtman, who now works at Technion:

Share