STRONGER THAN STEEL!
Human tissue tears all too easily; spider silk is stronger than steel. So at Utah State, researchers are spinning spider silk into a fix for damaged shoulders and knees. They bred transgenic goats to produce large volumes of spider-silk proteins, spun those proteins into strands, and braided the strands into a fiber. The filaments retain the silk’s stretchiness but are 100 times as strong as human ligaments and up to 20 times as strong as tendons. Spider silk could also make bone grafts less brittle, says Markus Buehler, who combines spider-silk proteins with collagen at MIT. Both groups estimate spider-silk implants could be approved for use in humans by 2030. —Sarah Fecht
Skin doesn’t just protect the body—it transmits sensations. By making electronics soft and fleshy, engineers have found a way to make the artificial skin covering grafts and prosthetics feel something, too. Researchers at the University of Illinois have created circuits thin and flexible enough to cover a fingertip, where they convert pressure into electrical signals. A gel developed at Stanford, capable of storing electricity, could become a moldable battery. And Carnegie Mellon’s Carmel Majidi is trying to turn rubber into pressure and friction sensors. He embeds it with small channels of liquid metal, which change conductivity as the liquid moves. Electronic skin may be useful to nonhumans, too. “This approach to engineering could potentially make robots and machines a lot more lifelike,” Majidi says. —Lauren Aaronson
A SAFER NUCLEAR REACTOR
The nation’s 104 nuclear power plants rely heavily on steel for many of their components, including the pressure vessels that contain uranium. But eventually, the steady barrage of radiation can degrade steel, making it susceptible to fractures. Researchers at Caltech and Los Alamos National Laboratory have created nanolaminate composites, materials that could better disaster-proof future reactors. The interfaces between the composites’ metal layers absorb the radiationinduced defects that cause irradiated material to become brittle. In the near term, the laminates could be incorporated into steel to replace aging parts in existing plants, says Caltech engineer Julia Greer. Spacecraft materials could also be coated with nanolaminates, safeguarding them against the cosmic radiation of deep space. —LA.
HEAT-SEEKING SOLAR PANELS
Like sunflowers bending toward light, solar panels can increase their energy output by rotating as the sun moves. But swiveling requires energy too. “Not many materials can respond to sunlight and also have a mechanical response,” says Hongrui Jiang, an engineer at the University of Wisconsin at Madison. Jiang developed a material that could passively shift the base of a solar array. He combined carbon nanotubes, which absorb sunlight, with a liquid-crystalline elastomer (LCE) that contracts when it heats up. As solar energy warms one side of the base, the LCE shrinks, causing the solar panel to tilt toward the sun; once that side falls into shadow, the LCE cools and returns to its original height. Field tests show the system Increases the efficiency of solar panels by an average of 10 percent. —S.F.
Bacterial infections caught at U.S. hospitals kill about 100,000 patients annually; staff must continually sterilize surfaces to halt their spread. A material pioneered by a Harvard lab could prevent organisms from growing on medical equipment like catheters in the first place—It’s so slippery not even bacteria can stick to it. Based on SLIPS (slippery liquid-infused porous surfaces) technology, it leverages the same mechanism that causes insects to slide into a pitcher plant. Nanopores texturing a solid base, such as Teflon or metal, wick an ultrasmooth lubricant to it; everything else, including germs, simply slides off the liquid coating. Harvard materials scientist Tak-Sing Wong says SLIPS have the same effect on dust, ice, and graffiti, making them potentially useful to many more industries. —Laura Geggel