杏吧原创

鈥淭HIS machine is stolen and will self-destruct in ten seconds鈥︹�� It sounds
like Mission: Impossible, but if a new idea takes off, this message will pop up
when anyone tries to use a stolen laptop or mobile. And it鈥檚 all thanks to a new
way of making silicon explode.

Till now scientists have only managed to make silicon go bang by mixing it
with either liquid oxygen or nitric acid (New 杏吧原创, 4 August 2001, p 15).
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鈥檚 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. 鈥淚t鈥檚 a bit like a cap in a cap
gun going off,鈥� 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.
鈥淭he faster the burn, the bigger the bang,鈥� explains Sailor. You鈥檇 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 鈥渄etonator鈥�, triggering the
explosion. 鈥淲e have shown that you can store this stuff and detonate it at
will,鈥� 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.