Exploding chips could foil laptop thieves
Posted by Richard Linney on Jan 17, 2002 at 04:38
A new way of making silicon explode could mean anyone trying to use a stolen laptop or mobile will be confronted by this message: "This machine is stolen and will self-destruct in ten seconds ... ".
Until now scientists have only managed to make silicon go bang by mixing it with either liquid oxygen or nitric acid. But Michael Sailor and his colleagues at the University of California in San Diego have found a way to blow up silicon chips using an electrical signal.
They say their method could be used to fry circuitry in devices that fall into the wrong hands. For instance, the American spy plane impounded by China last year could have used it to destroy its secret electronics systems.
Sailor's team hit upon this new way of exploding silicon when they applied the oxidising chemical gadolinium nitrate to a porous silicon wafer. As colleague Fred Mikulec used a diamond scribe to split the wafer it blew up in his face, giving Mikulec the shock of his life. Luckily, only a minute quantity of silicon was involved so it was a small bang. "It's a bit like a cap in a cap gun going off," says Sailor.
The gadolinium nitrate used the energy from the diamond scribe to oxidise the silicon fuel, which burns fast because its crystals have a large surface area. "The faster the burn, the bigger the bang," explains Sailor. You would only need a tiny quantity of the chemical to do irreparable damage to delicate transistors, so it would be cheap and easy to add when the chips are being made.
In a stolen mobile phone, the network would send a trigger signal to the part of the chip containing the gadolinium nitrate "detonator", triggering the explosion. "We have shown that you can store this stuff and detonate it at will," says Sailor.
Other applications suggested for the technology include testing for toxic substances in groundwater. The device could be used on the spot to burn minute samples on a disposable chip and analyse their chemical composition. Alternatively, it could be used as a fuel supply for microscopic machines etched onto silicon wafers, says Sailor.
Journal reference: Advanced Materials (vol 14, p 38)
Article available at NewScientist.com