Nanotechnology Now

Our NanoNews Digest Sponsors





Heifer International

Wikipedia Affiliate Button


android tablet pc

Home > Press > Tough, light and strong: Lessons from nature could lead to the creation of new materials

The interior of the toucan’s beak is rigid "foam" made of bony fibers and drum-like membranes sandwiched between outer layers of keratin, the protein that makes up fingernails, hair and horn. The result is solid “foam” made of air-tight cells that gives the beak additional rigidity. Like a house covered by a shingled roof, the foam is covered with overlapping keratin tiles, each about 50 micrometers in diameter and 1 micrometer thick, which are glued together to produce sheets.

Credit: Marc Meyers/Jacobs School of Engineering, UC San Diego
The interior of the toucan’s beak is rigid "foam" made of bony fibers and drum-like membranes sandwiched between outer layers of keratin, the protein that makes up fingernails, hair and horn. The result is solid “foam” made of air-tight cells that gives the beak additional rigidity. Like a house covered by a shingled roof, the foam is covered with overlapping keratin tiles, each about 50 micrometers in diameter and 1 micrometer thick, which are glued together to produce sheets.

Credit: Marc Meyers/Jacobs School of Engineering, UC San Diego

Abstract:
In a sweeping review of the field of bio-inspired engineering and biomimicry in the Feb. 15 issue of the journal Science, two engineers at the University of California, San Diego, identify three characteristics of biological materials that they believe engineers would do well to emulate in man-made materials: light weight, toughness and strength.

Tough, light and strong: Lessons from nature could lead to the creation of new materials

San Diego, CA | Posted on February 14th, 2013

Joanna McKittrick and Marc Meyers, from the materials science program at the Jacobs School of Engineering at UC San Diego, examine the three characteristics in a wide range of materials, from spider silk, to lobster and abalone shells, to toucan beaks and porcupine quills. Lessons learned from these materials could lead to better body armor, lighter aircraft and stronger, more flexible materials, researchers said.

3-D printing offers new opportunities to fabricate these materials, engineers said. "An abalone doesn't grow a shell overnight," McKittrick said. "But you could build a material similar to the abalone shell using principles we learned from nature by printing layer upon layer of mineral deposits—and do it much faster than nature would."

Meyers and McKittrick have been studying bio-inspired designs for more than a decade and were commissioned to write a research review on the topic by Science. Over the years, they have used a wide array of advanced tools, from

X-ray diffraction to electron microscopy; and developed tests of materials' mechanical properties at the nanoscale, to understand the underlying structure of materials found in animals and plants. "Mother Nature gives us templates," said McKittrick. "We are trying to understand them better so we can implement them in new materials."

"We outline the mechanisms that can help us elucidate the properties of biological materials," Meyers said. Bio-inspired designs have been a part of science and engineering for a long time—from the legend of Icarus, to Leonardo Da Vinci's flying machines, inspired by birds, to modern-day materials such as Velcro, Meyers pointed out.

Tough materials: the importance of interfaces

Tough materials deflect cracks by erecting various obstacles that prevent cracks from propagating in a straight line. Materials in nature use various strategies to achieve this result. One is to embed stretchy collagen fibers in brittle minerals. Another is the use of interfaces between layers of materials to create obstacles.

For example, at the nanoscale, an abalone shell is made of thousands of layers of "tiles" made of calcium carbonate (more commonly known as chalk), about 10 micrometers across and 0.5 micrometer thick—about one-one hundredth the thickness of a strand of human hair. The irregular stacks of thin tiles refract light to yield the characteristic luster of mother of pearl. They are organized in a highly ordered brick-like structure arranged in the toughest configuration theoretically possible.

A key to the strength of the abalone shell, Meyers said, is a protein adhesive that binds to the top and bottom surfaces of the calcium carbonate tiles. The glue is strong enough to hold layers of tiles firmly together, but weak enough to permit the layers to slip apart, absorbing the energy of a heavy blow in the process. Abalones quickly fill in fissures due to impacts, and they also deposit "growth bands" of organic material during seasonal lulls in shell growth. The growth bands further strengthen the shells. Meyers believes that designs inspired by the structure of the abalone shell could help improve advanced ceramic materials in the future.

Lightweight structures: shells and foams

Animals have developed incredibly light yet tough structures compatible with motion, including flight. Think of bird feathers, porcupine quills and bird beaks. These structures are made of materials that don't bend while being as light as possible. Most are made of tube-like structures with a fairly large diameter. But when the tubes' diameter reaches a certain size, they become increasingly likely to buckle. To increase resistance to buckling, the tubes are then filled with a foam-like substance.

For example, the interior of the toucan's beak is rigid "foam" made of bony fibers and drum-like membranes sandwiched between outer layers of keratin, the protein that makes up fingernails, hair and horn. The result is solid "foam" made of air-tight cells that gives the beak additional rigidity. Like a house covered by a shingled roof, the foam is covered with overlapping keratin tiles, each about 50 micrometers in diameter and 1 micrometer thick, which are glued together to produce sheets.

Meyers said the bio-composite found in the toucan's beak could inspire the design of ultra-light aircraft and vehicle components. The researchers also describe other strategies to make lightweight objects. Some bird wing bones have strut-like structures inside them as reinforcements. Bamboo is made of segments that don't crack.

"Natural systems are built from so few elements, yet they use ingenious ways to assemble all these different materials to maximize their properties," McKittrick said.

Strong materials: the importance of biopolymers

Biopolymers, such as collagen, are a key component of strong natural materials. At lower stress levels, they can undergo considerable stretching, their molecules uncoiling and unkinking, without breaking. At higher stress levels, it's the polymer's backbone itself that stretches. These biopolymers are found between stiff minerals, giving materials their natural strength.

For example, spider silk has both high tensile strength and extensibility. "It's stronger than almost any material," Meyers said. The si¬lk is made of pleated sheets of nanocrystals connected by weak hydrogen bonds and embedded in protein strands. Under low stress, the protein strands uncoil and straighten, much like biopolymers. Under larger stress, the load gets transferred to the nanocrystals. If necessary, some of the hydrogen bonds slip, allowing the structure to stretch without breaking. Silk's reliance on hydrogen bonds for strength suggests that researchers may need to pursue new avenues to engineer stronger materials, Meyers said. Incidentally, similar structures can be found in bone, where sacrificial hydrogen bonds between mineralized collagen fibrils impart excellent fracture resistance.

More complex strong structures can be found in everything from wool to whelk eggs.

Real-life examples of bioinspired materials and design

Beyond Velcro, there are multiple examples of bio-inspired materials and design. Swimsuits for competitive swimmers were built to replicate the ridges that reduce drag on shark skin (and were later banned from competition). Researchers at MIT have developed a surgical tape based on the structure of the gecko's sticky paws. Irregularities found on whale fins reduce drag and are now used in turbine blade designs.

Researchers believe more, and better, materials are yet to come. "There are a tremendous number of examples of things we can't do with traditional materials," McKittrick said. "It's going to take more time to make these bio-inspired materials. But they will be better."

"This field is here to stay," Meyers said.

####

For more information, please click here

Contacts:
Ioana Patringenaru

858-822-0899

Copyright © University of California - San Diego

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

News and information

HP Supercomputer at NREL Garners Top Honor October 19th, 2014

First Canada Excellence Research Chair gets $10 million from the federal government for oilsands research at the University of Calgary: Federal government announces prestigious research chair to study improving oil production efficiency October 19th, 2014

Ucore's McKenzie to Deliver Presentation to Rare Earths Conference in Singapore as Highlight of Fall 2014 Marketplace Schedule October 19th, 2014

Non-Toxic Nanocatalysts Open New Window for Significant Decrease in Reaction Process October 19th, 2014

Discoveries

Non-Toxic Nanocatalysts Open New Window for Significant Decrease in Reaction Process October 19th, 2014

Plastic nanoparticles also harm freshwater organisms October 18th, 2014

Superconducting circuits, simplified: New circuit design could unlock the power of experimental superconducting computer chips October 18th, 2014

Nanotechnology Improves Quality of Anti-Corrosive Coatings October 17th, 2014

Materials/Metamaterials

Nanotechnology Improves Quality of Anti-Corrosive Coatings October 17th, 2014

Graphenea opens US branch October 16th, 2014

3DXNano™ ESD Carbon Nanotube 3D Printing Filament - optimized for demanding 3D printing applications in the semi-con and electronics industry October 16th, 2014

Nanocoatings Market By Product Is Expected To Reach USD 8.17 Billion By 2020: Grand View Research, Inc. October 15th, 2014

Announcements

HP Supercomputer at NREL Garners Top Honor October 19th, 2014

First Canada Excellence Research Chair gets $10 million from the federal government for oilsands research at the University of Calgary: Federal government announces prestigious research chair to study improving oil production efficiency October 19th, 2014

Ucore's McKenzie to Deliver Presentation to Rare Earths Conference in Singapore as Highlight of Fall 2014 Marketplace Schedule October 19th, 2014

Non-Toxic Nanocatalysts Open New Window for Significant Decrease in Reaction Process October 19th, 2014

Tools

New Grand ARM Transmission Electron Microscope Offers Highest Commercially-Available Atomic Resolution of 63 Picometers October 17th, 2014

Nanodevices for clinical diagnostic with potential for the international market: The development is based on optical principles and provides precision and allows saving vital time for the patient October 15th, 2014

Nanotronics Imaging Releases nSPEC® 3D, Powerful Microscope That Captures 3D Images at Nanoscale, in Lightning Speed: Company Unveils Design at American Chemical Society 2014 International Elastomer Conference October 14th, 2014

Unique catalysts for hydrogen fuel cells synthesized in ordinary kitchen microwave oven October 14th, 2014

NanoNews-Digest
The latest news from around the world, FREE





  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More














ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2014 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE