Science

"Layer cake" chip detects cocaine

A scanning electron microscope image shows the surface of the chip, on which gold nanoparticles (small bright dots) have been deposited over silver nanoparticles (light grey regions)
A scanning electron microscope image shows the surface of the chip, on which gold nanoparticles (small bright dots) have been deposited over silver nanoparticles (light grey regions)
View 1 Image
A scanning electron microscope image shows the surface of the chip, on which gold nanoparticles (small bright dots) have been deposited over silver nanoparticles (light grey regions)
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A scanning electron microscope image shows the surface of the chip, on which gold nanoparticles (small bright dots) have been deposited over silver nanoparticles (light grey regions)

We're getting one step closer to a portable, practical and affordable "cocaine breathalyzer," thanks to research being conducted at the University at Buffalo. Scientists there have created a chip that detects the drug in samples of a person's blood, breath, urine or saliva.

Created by a team led by associate professor Qiaoqiang Gan (who recently brought us a new-and-improved solar still), the chip utilizes a process known as surface-enhanced Raman spectroscopy, and is described as being like an "optical layer cake."

On the bottom is a horizontal layer of silver, which acts as a mirror. Sitting on top of that is a layer of dielectric material such as silicon dioxide or aluminum oxide (a dielectric material is an insulator through which no electrical current can flow, but that does become electrically polarized when voltage is applied to it). Finally, on the very top is an "active layer" made up of light-trapping gold and silver nanoparticles.

The idea is that the chip would be built into a handheld device, which would start by extracting cocaine molecules from a provided biological sample. Those molecules – assuming there were any – would then get deposited on the surface of the chip, where they would fall between the nanoparticles.

When the chip is exposed to a laser light source, the mirror and the dielectric material manipulate the light, causing an increase in the number of photons at the active surface layer. This intensifies the manner in which the cocaine molecules scatter the light trapped by the nanoparticles. The handheld device would be able to analyze that distinct light-scattering signature, and determine if it matched the signature known to be produced by cocaine. It could conceivably also identify the unique light-scattering signatures of other drugs, such as marijuana.

"The high-performance chip we designed was able to detect cocaine within minutes in our experiments," says Gan. "It's also inexpensive. It can be produced using raw materials that cost around 10 cents, and the fabrication techniques we used are also low-cost."

A paper on the research was recently published in the journal Small Methods.

For other approaches to cocaine detection, check out the work that's been done at the University of Surrey and the VTT Technical Research Centre of Finland.

Source: University at Buffalo

4 comments
Catweazle
That could be a problem for London where cocaine is now so prevalent that most Londoners would test positive using modern high sensitivity test instruments whether they are users or not.
MartinVoelker
I predict a major stock crash when they install this at the entrance to the Wall Street NYSE trading floor and no one gets in.
Martin Kinnaman
So how much is this research cost just to make the drug war a little more slick? Hopefully this vibrational technique can be applied to actual medicine.
Wolf0579
I could give a rat's ass about anyone doing coke. What I DO worry about is someone T-boning me at 50 mph, after running a stop sign or red light because they're DRUNK. You idiots need to give up on your dinosaur dreams of drug war. Pot, cocaine, acid, are all "driveable" drugs. They do not affect your motor coordination much to the police and courts' financial consternation. Worry about THE LEGAL DRUG OF ALCOHOL. It's killed far, far more people than the illegal kind.
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