April 1, 2007 Polymer chemists have created a flexible, indestructible material, called metal rubber, that can be heated, frozen, washed or doused with jet fuel, and still retain its electricity-conducting properties. To make metal rubber, chemists and engineers use a process called self-assembly. The material is repeatedly dipped into positively charged and negatively charged solutions. The positive and negative charges bond, forming layers that conduct electricity. Uses of metal rubber include bendy, electrically charged aircraft wings, artificial muscles and wearable computers.
Portable gadgets were meant to be taken on the move. Portable also means accidents and damage can happen. Now, imagine electronics that can take a beating and bounce back! It's soon possible with a shocking new flexible, indestructible material, called metal rubber.
"You can heat it. You can freeze it. You can stretch it. You can douse it with jet fuel," Jennifer Lalli, a polymer chemist at NanoSonic, Inc., in Blacksburg, Va., tells DBIS.
Abuse it, and metal rubber snaps back to its original shape. But the best part of this rubbery material? It conducts electricity just like metal and is also lightweight.
To make metal rubber, chemists and engineers use a process called self-assembly. The material is repeatedly dipped into positively charged and negatively charged solutions. The positive and negative charges bond, forming layers that conduct electricity.
"Electricity flows through metal rubber because there are little metal particles, and the electricity flows from little metal particle, to little metal particle, to little metal particle, between the two ends just like a piece of copper metal," Rick Claus, a NanoSonic electrical engineer, tells DBIS.
The self-assembly process coats almost anything -- even fabric can be made to carry electrical power. Lalli says you can wash the metal rubber textiles and they maintain electrical current.
Scientists are looking into uses of metal rubber like bendy, electrically charged aircraft wings and artificial muscles -- and wearable computers. Abuse-resistant, flexible circuits, like cell phones, are still years away, but the future looks bright -- and powerful -- for bendable products.
The Materials Research Society contributed to the information contained in the TV portion of this report.
BACKGROUND: Materials engineers and chemists at NanoSonic, Inc. have developed a way to produce lightweight electrically conductive textiles that won't break or disintegrate when you wash or stretch them. This makes the textiles perfect for use in sensor-laden 'smart clothes.' An important component is the company's trademarked metal rubber, a substance that has the elasticity of rubber and ability of steel to conduct electricity/ NanoSonic's metal rubber and e-textiles could find use in protective clothing; flexible antennae and circuits; flexible displays; electromagnetic shielding; biomedical sensors and health monitoring; and applications in outer space.
HOW IT'S MADE: Instead of just mixing different materials together, like in a blender or weaving metal wire components into fabrics, NanoSonic's manufacturing technique is a bit like 'growing' textiles in a makeshift washing machine. It's called "electrostatic self-assembly." By dipping the base material into baths of alternating electrons and protons, those nanoparticles with opposite charges attract and stick to each other like Velcro. So many different properties can be linked together without the material falling apart when it is washed or stretched. Each dip adds one layer. The e-textiles are lower in weight, with lower manufacturing costs and few byproducts, plus they can withstand repeated washings without falling apart.
EXAMPLES: In combat conditions, a US solder clothed in layers of garments made from e-textiles could wear sensors close to the skin that monitor blood pressure, body temperature, and heart rate. Another layer could be integrated into the Kevlar vest to register impact from a bullet or shrapnel. And sensors in an outer garment could 'sniff' the air for toxic agents of chemical or biological warfare. It might also be possible to make a thicker but lightweight conductive fabric for electric power workers that would not limit their range of motion, but would reduce the effects of electric power line radiation.
ABOUT SELF-ASSEMBLY: There are two basic ways to manipulate matter. On the large scale, we pick things up with our hands and physically put them together. Nature uses self-assembly, assembling its structures molecule by tiny molecule. Spread out in a liquid, the miniature parts jostle about and come together in random configurations, gradually matching up through trial and error according to shape and electrical charges. It's as if you shook a box holding the pieces of a jigsaw puzzle, and looked in to find the puzzle had assembled itself. Yet biological systems, as well as several inorganic physical systems, exhibit self-assembling or self-ordering behavior all the time.