Nanotech device mimics dog's nose to detect explosives

22nd November 2012

Inspired by the biology of canine scent receptors, UC Santa Barbara scientists have made a chip capable of rapidly identifying trace amounts of vapour molecules.

Portable, accurate and highly sensitive devices that "sniff out" vapours from explosives and other substances may soon be as commonplace as smoke detectors in public places, thanks to researchers at the University of California, Santa Barbara.

Researchers at UCSB, led by Carl Meinhart and Martin Moskovits, have designed a detector that 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 Meinhart. "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's detecting."

Results published in the latest Analytical Chemistry show that their device can detect airborne molecules of a chemical called 2,4-dinitrotoluene, the primary vapour emanating from TNT-based explosives. The system provides continuous, real-time monitoring at concentrations of just 1 part per billion (ppb).

The human nose cannot detect such minute amounts of a substance, but “sniffer” dogs can do so. The device is inspired by the biological design and microscale size of the canine olfactory mucus layer, which absorbs and then concentrates airborne molecules.

“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.

Packaged on a fingerprint-sized microchip and fabricated at UCSB’s state-of-the-art cleanroom facility, the underlying technology combines free-surface microfluidics and surface-enhanced Raman spectroscopy (SERS) to capture and identify specific molecules. A microscale channel of liquid absorbs and concentrates the molecules by up to six orders of magnitude. Once the molecules are absorbed into the microchannel, they interact with nanoparticles that amplify their spectral signature when excited by laser light. A computer database of spectral signatures identifies what kind of molecule has been captured.

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