High power and low-power damage, side by side
Three years ago, Apple's iPhone 4 launch was marred by the grip of death. If you held the iPhone [just so](http://stag-komodo.wired.com/gadgetlab/2010/06/iphone-4-holding-it-wrong/), your hand could interfere with the phone's antenna. Calls would drop, and web surfing would suck.
It was a PR nightmare for Apple, which eventually handed out free plastic bumpers that could fix the problem. But now, researchers at the California Institute of Technology say they're developing a [new approach to chipmaking](http://www.caltech.edu/content/creating-indestructible-self-healing-circuits) that could prevent this -- and crack down on a few other chip problems as well.
They've built a new kind of "self-healing" processor. Basically, it can reorganize itself when confronted with something like the Apple death grip, or worse.
To test their chips, the Caltech researchers blasted out components in specially built chips, similar to the kind of power amplifier chips you'd find in your mobile phone. They found that their their chips could fix themselves and keep on working even after being blasted by lasers. When they are first disrupted, the test chips waste a lot of power, but as they heal themselves, they automatically figure out the best state to change into, in order to keep working as efficiently as possible.
That's a big deal. With most chips, if a single transistor fails, it's enough to put it out of service. The Caltech chips, however, are equipped with sensors and a kind of digital immune system that allows them to alter the way they operate, bringing in new resources to replace whatever has been damaged, even after they've been blasted with lasers.
"Every so often a transistor blows up," says Caltech Professor Ali Hajimiri. "In a current chip -- if you have a microprocessor or a radio transceiver on your cellular phone -- if one transistor is gone, the entire chip is useless."
Hajimiri hopes that these self-healing techniques could be used by chipmakers to build more robust processors and to boost yield rates of existing chips. They'd do that by fixing chips that would have once been considered unusable.
To complete their research, the team used lasers to torture their microprocessors in a variety of ways, which you can see in the images above.
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A laser-blasted chip, captured via electron microscope. The Caltech team aimed a high power laser at very small areas of the chip. "We hit them with different powers of laser and different focus, and with a different size of the laser," says Hajimiri. So the damage runs from the precise vaporization of the top layer of the chip (bottom left) to deeper, more powerful shots, with a the laser focused beneath the surface of the chip. With these hits, right, you get the messier, chip-blown-up kind of effect.
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