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Super Goop An Ambiguous Substance Could Animate Robots, Prevent Earthquake Damage By Amanda Onion Oct. 2 A fluid that can transform from a liquid to a solid within milliseconds could soon be running through the "veins" of robots to give them a soft, human-like touch. Super Goop to Be Pumped in Robot Veins When not near a magnetic pull, so-called MR fluids appear as gray, unextraordinary oily liquids. But apply a magnetic force and the fluid instantly becomes the texture of thick clay. By pumping the fluid into an electronic sensing system that activates a magnetic field, it can be used to power robots, stabilize buildings and smooth bumpy automobile rides. "These fluids have properties that can change in an instant when you apply magnetic fields," says Henri Gavin, a professor of engineering at Duke University. "This gives great flexibility in how you can design devices." MR fluids are not new the substance was discovered in the 1940s but recently the fluid has been improved and researchers are devising new ways of putting it to use. The stiffness of the fluids can now be adjusted a thousand times a second. NASA thinks they can do better and will be sending an MR fluid experiment to the space station in November to study the fluid so they can further improve it. "We're trying to take it to the next level," says Juan Agui, project scientist with NASA Glenn Research Center in Cleveland, Ohio. Iron in Oil MR fluid is already applied in a wide range of mechanisms. It's used to provide resistance in Nautilus home step machines and exercise bicycles. The fluid is incorporated into advanced shock absorption systems in some cars and even prosthetic limbs. And North Carolina's Lord Corporation is now working on developing washing machines with the magnetic dampers so they can operate with little vibration and virtually no noise. Some are hopeful it could offer the next wave in building stabilization. Engineers in Japan have become the first to install the technology to help stabilize buildings against tremors. And China's Dong Ting Lake Bridge is kept steady by the technology. A primitive version of MR fluid can be crafted by adding iron filings to corn oil. Hold a magnet nearby and the mixture stiffens as the iron filings form lattice structures pointing toward the magnet. Professional MR fluids contain basically the same mix, but use a specially designed hydrocarbon as the oil and soft iron particles shaved so small that a bag of them looks like dark sand. Researchers at the University of Pittsburgh recently concocted another substance for adding to the mix that prevents a common problem clumping. "The additive transforms the fluid from a free flowing liquid to something like a yogurt over a period of hours," explains Gavin. "The 'yogurt' holds the iron filings in place." When activated, Gavin explains, the yogurt-like substance instantly becomes liquid again and then transforms into its stiffer, more solid form. This kind of advance is particularly key for damping systems in buildings since the MR fluid is rarely activated and iron filings are more likely to clump after time. Gavin explains the MR fluid would be placed in a shock absorbing system that fits into an isolation system of a building. As motion detectors sense movement, they trigger a matching magnetic pulse. The pulse then stiffens the MR fluid accordingly and steels the building against shaking. General Motors is installing the magnetic damping system in the seats of their 2003 Corvette and Oldsmobile models to offer a super smooth ride. Prosthetic joint manufacturers have also begun installing MR fluids in artificial leg joints to soften a wearer's steps. And Russian company recently announced plans to use MR fluids in super cushioned running shoes. Fighting Clumping in Space This November, engineers at NASA and the Massachusetts Institute of Technology hope to better understand how the tiny suspended particles interact and improve the fluid's performance by studying their interaction in the low gravity environment of the space station. "The force between any two particles is minuscule," explains Alice Gast, a professor of chemical engineering at MIT who is leading the research. "We think by understanding the details of these forces, we'll be able to understand how to keep the filings from clumping and make them more effective." The research could eventually be applied to help NASA smooth space station docking, minimize wear and tear from repositioning satellites and better suppress vibrations during rocket launches. But Gast believes one of the best applications for the fluid will be in animating the hands and limbs of robots so they move as naturally as any human's. "Think about using a robot to pick up an egg," she says. "If the magnetic fluid were running in the veins of the hand you could tune it so it would apply just the right force and no eggs would be broken." |