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Chemical Sensor as Sensitive as a Dog's Nose

A technological scent sensor that works in almost the exact same manner as a bog's biological nose has been developed by researchers at the University of California. The sensor, the size of an adult male fingerprint, uses microfluidic nanotechnology to mimic the biological mechanism behind canine scent receptors. The device is both highly sensitive to trace amounts of certain vapour molecules, and able to tell a specific substance apart from similar molecules.

"Dogs are still the gold standard for scent detection of explosives. But like a person, a dog can have a good day or a bad day, get tired or distracted," said professor Carl Meinhart of the department of mechanical engineering, the individual who led the study. "We have developed a device with the same or better sensitivity as a dog's nose that feeds into a computer to report exactly what kind of molecule it is detecting."

"The device is capable of real-time detection and identification of certain types of molecules at concentrations of 1 ppb or below. Its specificity and sensitivity are unparalleled," said Dr. Brian Piorek, former mechanical engineering doctoral student in Meinhart's laboratory and Chief Scientist at Santa Barbara-based SpectraFluidics, Inc . The technology has been patented and exclusively licensed to SpectraFluidics, a company that Piorek co-founded in 2008 with private investors.
"Our research project not only brings different disciplines together to develop something new, but it also creates jobs for the local community and hopefully benefits society in general," commented Meinhart.

The first results were published earlier this month in the journal Analytical Chemistry. They show that the sensor is capable of detecting airborne molecules of a chemical called 2,4-dinitrotoluene, the primary vapor emanating from TNT-based explosives. The human nose cannot detect such minute amounts of a substance, but "sniffer" dogs have long been used to track these types of molecules. For the first time, we now have a technological sensor – small enough to integrate into a handheld device – that can do the same thing. This opens up the possibility of equipping every investigative officer with one, rather than relying solely on specialised dog teams.

Granted the sensor cannot do everything the sniffer dog can, as it only has the dog's sense of smell, not the dog's sense of hearing or agile mind, but there are many instances where it would not be practical to bring a dog into the equation, but very practical to use the sensor. An example would be in looking for chemicals in refrigerated meat vans. Another would be any situation where chemicals hazardous to your health, are already present in the air. Dogs have to breathe after all.

The technology underlying the sensor is a hybrid. It uses a combination of the same technology every biochip lab uses – microfluidics – and a miniature spectrometer. The microfluidics forms a host of small channels which trap molecules from the air, and force them to flow down the channels, which all merge together in a single river just as they pass the spectrometer. As such, it analyses every molecule the device has collected. Once the molecules have been analysed by the spectrometer, the microfluidic channel carries them out of the device altogether.

"The technology could be used to detect a very wide variety of molecules," said Meinhart. "The applications could extend to certain disease diagnosis or narcotics detection, to name a few."
Moskovits added, "The paper we published focused on explosives, but it doesn't have to be explosives. It could detect molecules from someone's breath that may indicate disease, for example, or food that has spoiled."
The fundamental research was developed through an interdisciplinary collaboration between Professors Meinhart and Moskovits, and carried out by former doctoral researchers Dr. Piorek and Dr. Seung-Joon Lee. Their project was funded in part by UCSB's Institute for Collaborative Biotechnologies through the Army Research Office and DARPA.


Nanotech Device Mimics Dog's Nose to Detect Explosives

SpectraFluidics: The company commercialising the research

Free-Surface Microfluidics/Surface-Enhanced Raman Spectroscopy for Real-Time Trace Vapor Detection of Explosives (Paper, Paywalled)

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