Spray-On Explosive Detector


William Trogler and his team at the University of California, San Diego, made a silafluorene-fluorene copolymer to identify nitrogen-containing explosives. It is the first of its kind to act as a switchable sensor with picogram (10-15g) detection limits, and is reported in the Royal Society of Chemistry’s Journal of Materials Chemistry.

Trogler’s polymer can detect explosives at much lower levels than existing systems because it detects particles instead of explosive vapours. In the team’s new method one simply sprays the polymer solution over the test area, let it dry, and shine UV light on it. Spots of explosive quench the fluorescent polymer and turn blue….

Posted on May 28, 2008 at 12:40 PM22 Comments


R. May 28, 2008 12:53 PM

If those get deployed at airports someone will put a bucket of fine powdered nitrates in the back of a truck and drive along the roads towards the local airport.

The trailing cloud will contaminate enough passengers…

Carlo Graziani May 28, 2008 1:24 PM

So they can detect a 1.0E-24 kiloton explosive device? That must come in handy.

alan May 28, 2008 1:31 PM

Got a boss who travels a lot and whom you can’t stand? Just spray a little “Spray-N-Grow” on their luggage and watch the fun!

A little bit of nitrates makes the Boss go down…

Joe Buck May 28, 2008 1:34 PM

We were traveling with my daughter, who was in diapers at the time, and her car seat triggered an airport explosives detector. The airport security guy said that this was very common: the nitrogen compounds in urine (urea is the main one) will set them off, and she had leaked on the seat a bit.

Don May 28, 2008 1:47 PM

I won’t be satisfied until every farmer in America is detained at Guantanamo!

Jason May 28, 2008 2:17 PM

You only thought the lines were long at airport security.
You ain’t seen nothing yet.
In the team’s new method one simply sprays the polymer solution over the test area, let it dry, and shine UV light on it.

“It hasn’t dried yet, step back behind the line.”

Clive Robinson May 28, 2008 2:25 PM

Any one remember “Aunt aggies bomb factory” during the 1970’s.

Well their hands were swabed and came up positive for explosives.

Turns out they had been using old playing cards with a nitro celulose finish (still quite common).

And for those that are realy realy old the exploding billiard balls?

Turns out that various compounds of nitrogen and celulose where the equivelent of the “plastic of their era” and turned up all over the place such as piano keys, billiard balls and even ash trays and knife handles. Oh and of course “celuloid” film stock.

All of these every day items many still in use will leave traces on your hands that will show up as possible explosives on swabs several days after handaling them.

Also don’t shake hands with anybody with a dodgy ticker they might have used their NG spray recently (yup it’s Tri Nitro Glycerin or blasting oil as used for making dynamite).

There are so many ways to come into contact with “nitro compounds” that it is going to be worse than cocaine on twenty dollar bills.

What is needed is not a more sensitive test but a more discriminating test otherwise the false positives are going to be something like 5-15% of the population.

Davi Ottenheimer May 28, 2008 4:40 PM

Reminds me of a UV light used to find urine stains. Very effective.

I bet the real inventor (will that member of Mr. Trogler’s team please stand up) has a carpeted home and pets.

Perhaps instead of the old spray and UV-light method they could propose a general mist to fall on passengers. This would create a pleasant cooling atmosphere while inspectors with special UV-lenses could mingle more freely and instantly see who has peed themselves or filled their diaper. Oh, wait, I was sidetracked by that comment about the child car seat…

Roy May 28, 2008 4:49 PM

I’ll expect a raft of false positive and all for nothing. If the spray would detect the presence of nitroglycerin and nitrocellulose, then it would detect the presence of anyone carrying a gun. Those are the principal constituents of double-based powder, the propellant in modern firearms.

If it fails to detect the nitro compounds inside the cartridges, then it is failing to detect nitro compounds that everyone knows are ubiquitous with security personnel. All that terrorists need to do to smuggle high explosives in is coat them with a thin film of lacquer.

Yojimbo May 28, 2008 7:01 PM

Ooh, combine this spray with the oxytocin “trust” spray … and you’ll have …

Actually, I’m not quite sure what you’ll have.

“Because you don’t have any explosives, I can give you my money” ?

Georg Ruß May 29, 2008 1:41 AM

[…] picogram (10-15g) […]

If the article really means “picogram” this should read 10^(-12) g. But of course, that’s just three orders of magnitude less sensitive 🙂


Anonymous May 29, 2008 5:45 AM

Spots of explosive quench the fluorescent polymer and turn blue….

Yeah, and I bet this reaction is like totally specific for things that go boom and will not react in any way whatsoever with normal everyday items… dream on!

Paul May 29, 2008 8:35 AM

It’s our awesome new energy conservation policy: make air travel so completely miserable that nobody will bother any more, thereby saving vast amounts of fuel and reducing pollution.


OK seriously, there are so many ways you could false positive for this, especially with such a low detection threshold. Just ask any of the remaining Birmingham Six about that one…

Hans May 29, 2008 3:23 PM

Easy one.

Make an explosive that triggers on the detection fluid. And we’re back in the Movie Plot Threats.

gotpasswords May 29, 2008 6:06 PM

Even if the stuff is useful for passenger / baggage screening, will the TSA agents be able or willing to clean whatever they’ve sprayed it on?

I’m a bit wary of a company that seems more concerned with featuring their new products on TV shows like CSI:Miami and being proud that they’re located within 30 minutes of the US Patent Office. (Is that 30 minutes by foot, car or email?)

paul May 29, 2008 8:09 PM

If this stuff actually works without significant false positives it could be disastrous for security. People will spray it in something and, if it comes up clean, assume that the something is hazard-free.

Doug Coulter May 30, 2008 7:55 PM

Many, but far from all explosives are nitrate based.
Some are chlorate based, and were developed in WWII when glycerin and other options were running short.
See “Chemistry of Powder and Explosives” or any other reference.

These give off the precise same chemical signature as freshly washed clothing…

IF they tried to detect them — think of the false positives, and movie-plot possibilities.

Brian Greer June 1, 2008 9:34 AM

Surely the false-positives involved with this make it useless in real world applications.

Steve July 16, 2008 5:40 PM

Thank God the airports are doing what they are doing to ensure our safety; whether it’s an inconvience to us or not. I’d be more than willing to strip totally naked in the terminal if I had to, rather than have a 500 mph wind tear my clothes off later.

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