Shrinkage.Printable electronics are about to become a whole lot smaller. Scientists have developed a new way to write electrically conducting silicon ink onto a plastic backing with five times more accuracy than previously possible. Whereas past printable electronics have manually placed components using, for example, inkjet printers, the researchers have developed an elaborate way of mak-ing the components fall into place like scattered iron filings spontaneously tracing out a picture, they report online the week of 11 January in the Proceedings of the National Academy of Sciences. The team demonstrated its self-assembly technique by building a flexible solar cell out of silicon crystals the thickness of a human hair (shown left, with magnified section showing crystals).
Bite strength.Zoom in on your tooth enamel, and you'll see this crisscrossing pattern of micron-sized crystals. But examine the thinner enamel of a frog's tooth, and you'll find smaller crystals with less intricate patterns. Researchers think the difference has to do with how many times an amino acid called proline repeats in amelogenin, a protein that acts like a scaffold for enamel's calcium minerals. The scientists synthesized versions of the protein with proline sequences of various lenghts and found an almost 5-fold increase in crystal size between the shortest and the longest. In addition, mice that had their more proline-rich amelogenin gene replaced by a proline-poor frog version lacked the tell-tale crisscross crystal pattern--and they had 50% thinner enamel, the researchers report online 22 December in PLoS Biology. The find may help scientists engineer new ways to grow tooth enamel to replace broken teeth.
Unforgettable. Flash memory devices have become popular because they can hold gobs of data and retain it even when their power supply has been cut off. But the silicon-based chips are too rigid and bulky for some applications, such as radio-frequency-identification transponders, basic versions of which are embedded into credit cards and ID badges. Now scientists have found a way around that problem by embedding the circuitry in flexible plastic semiconductors. In the 11 December issue of Science, researchers report that just like conventional flash memories, the devices can acquire data and maintain that data even when their power is off. But unlike their fatter cousins, the flexible chips can be folded into wallets.
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发表于 2010-1-15 21:40
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