極地打印機 再創磁鐵工作之法（片段！）
Polar Printer Reimagines the Way Magnets Work (With Video!)
A team of engineers in Alabama unveils an invention that reimagines the way magnets work, and that could change the way we do everything from closing the fridge to building frictionless gears.
一隊阿拉巴馬州的工程師，揭示一項發明 再創磁鐵的工作方式，它可能改變我們做每一件事的方法，從閉冰箱至建設無摩擦裝置。
By Joe Pappalardo
Published on: November 24, 2009
A startup company in Hunstville, Ala. has revealed an invention that can reconfigure the charges of magnets in never-before-seen patterns, a breakthrough that may lead to new varieties of contact-free attachments and friction-free gears. The company, Correlated Magnetics Research (CMR), creates magnets that, instead of carrying a positive charge on one end and a negative on the other, have complex field patterns that can be used to attract corresponding magnetic fields. When the correlated patterns on two magnets match, they attract and clasp. With a simple turn, the correlation is lost and the two sides can be easily separated.At the heart of the discovery is inventor Larry Fullerton, CEO and chief scientist of CMR and a former NASA scientist who worked on advanced radar and ultra-wideband communications technology. Fullerton's eureka moment occurred during a frustrating experience putting together toys for his grandchildren: "What if these could self-assemble?" he asked. "I knew it'd have to be done with magnets."
Most magnets used in self-assembly rely on electricity to switch their positive and negative poles to initiate action. But Fullerton's desire for a simpler solution led to a question: What if he could instill multiple magnetic poles, instead of just two, into magnetic material? In collaboration with company engineers, he created a machine that uses an electromagnetic print head to focus a high-intensity magnetic field to form new patterns in the material. The company has developed a more advanced technology that reprograms magnets by heating up material to above its Curie temperature, the maximum temperature at which a material can retain its magnetism. It then brings the material into contact with a magnetic structure that instills the material with new magnetic field patterns. When the material cools, the multipole pattern remains.
Experts say the physics makes sense, but add that the technology is not exotic. "It seems to be legitimate engineering," says Bill Butler, the director of the University of Alabama's Center for Materials for Information Technology. "It also seems to be elementary," he says. "That said, sometimes the best ideas are the simple ones." Butler says that CMR's technology is taking advantage of properties in rare-earth, high-coercivity magnets—which can maintain their polarization in strong magnetic fields.
Programmable magnets could be used for spaceship hatches, prosthetics ball joints, sports-equipment clasps and maglev-train hardware, according to the company. CMR is asking manufacturing companies to buy licenses to use the new technology in their products, so these magnets could conceivably turn up almost anywhere, especially in niche markets such as NASA hardware and military gear. In truly foolproof assembly directions, unlike those that plagued Fullerton, these smart magnets would ensure that every part links only where it belongs.
CMR is making prototype devices that demonstrate some other possibilities: Two handheld smart magnets mounted on handles clasp together tightly, but when they are twisted they come apart. This ability could come in handy in, say, tightly securing freezer doors—perfectly sealed with powerful magnets, but opened easily once the magnets rotate. Another key benefit of the arrangement becomes clear with this prototype: the attraction between correlated magnets falls off more quickly than that between traditional magnets as distance between the magnets increases. (The presence of so many positive and negative points close together saps the long-distance magnetic force. This is explained in some depth on the company's website.) This ability could allow for strong magnets to be used in everyday applications without destroying nearby credit cards, for instance, or it could control magnetic emissions used in medical imaging equipment that are not compatible with medical devices such as Pacemakers. For a closer look at the prototype in action and other possible uses for the magnets, check out the video below.
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