Carbon nanotubes could find use in improved bomb detection device

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Ling Zang with his prototype explosives sensor (Photo: Dan Hixon, University of Utah College of Engineering)

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Along with flame-retardant clothing, flexible supercapitors and a stronger alternative to carbon fiber, carbon nanotubes may soon have yet another application. Led by Prof. Ling Zang, a team of researchers at the University of Utah has integrated the tiny tubes of carbon atoms into a prototype explosives sensor. It can also detect illegal drugs and toxic chemicals such as nerve gas, reportedly doing so better than currently-used technologies.

The device utilizes two electrodes with a microscopic amount of carbon nanotubes located between them. When no explosive or toxic substances are present in the environment, electricity will flow between those electrodes – and through the nanotubes – at a consistent, known level.

If molecules of such a substance are present in sufficient quantities, however, the nanotubes will be affected. As a result, the current will either increase or decrease, depending on the substance in question – the nanotubes can be tuned to react to different substances, by modifying their surface structure using a polymer coating.

When the device detects such a change in current, it notifies the user.

In its present form, the prototype can detect over a dozen commonly-used explosives, and approximately two dozen toxic chemicals including sarin and chlorine. Because all of the nanotubes are exposed to the air, it is reportedly much more sensitive and accurate than existing explosives sensors, plus it delivers results in seconds as opposed to minutes. It should also be cost-effective, as the amount of nanotubes required in each device is so small.

A handheld commercial version of the device is now being developed by spinoff company Vaporsens, and is due for release early next year. The technology could also be added to existing security systems at places such as airports.

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