TAMING EXPLOSIVE CHIPS
Exploding silicon chips will soon find their way into car airbags, in the first application of a bizarre effect accidentally discovered by Dmitri Kovalev at the Technical University in Munich, Germany. During an experiment on a piece of porous silicon, the sample exploded and wrecked the lab (New 杏吧原创, 4 August 2001, p 15).
Tests showed that the massive internal surface area makes the silicon oxidise explosively, and researchers at the University of California, San Diego, later worked out how to trigger the effect electrically. Now the Munich team is collaborating with TRW Airbag Systems of Livonia, Michigan, to exploit this effect in a cheap, simple detonator. The prototype measures just a few millimetres square, and replaces the more costly and less reliable metal chloride detonator. The detonator triggers a second explosion, which will release the gas that inflates the airbag.
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ART TO DYE FOR
Museums and art galleries need to know how much light is falling on their exhibits, as excessive exposure makes paints and pigments fade. Electronic sensors are expensive, so researchers from five labs in Europe, headed by Germany鈥檚 Fraunhofer Institute for Silicate research in W眉rzburg, have been developing a cheap alternative.
Their sensor, which they unveiled at a meeting in Florence, Italy, last week, is coated with a patented silica matrix containing a blue dye that fades at a predictable rate when exposed to light. The resulting colour can be regularly checked against a colour chart to make sure an exhibit is not too brightly lit.
JACKET MAKES ENGINES GREENER
Car engines produce far more pollution when they are cold than when fully warmed up, and also wear faster. The solution could be to keep them warm.
Researchers have developed an insulating casing that drastically slows the loss of heat. At an ambient temperature of 20 掳C, a Volkswagen Golf engine insulated in this way took up to 15 hours to cool to 40 掳C, compared with 2 to 3 hours for a 鈥渘aked鈥� engine.
By reducing the number of cold starts, the insulation should cut emissions of pollutants, say the inventors, who come from the University of Applied Sciences in Cologne, Germany, and Elastogran, a subsidiary of the chemicals giant BASF.
Their casing contains blocks of polyurethane and can easily be dismantled to give mechanics access to the engine. Polyurethane foam was chosen as it provides the best insulation with the minimum weight.
Elastogran says cars cannot be retro-fitted with the new casing as a redesign would be needed to accommodate it. But the company is in negotiations with a major car manufacturer to produce a prototype.
