Now, a device that mimics dog's nose to detect explosives

According to researchers from University of California, portable, accurate and highly sensitive devices that sniff out vapours from explosives and other substances could become as commonplace as smoke detectors in public places.

Researchers led by professors 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," he said.

Results show that their device can detect airborne molecules of a chemical called 2,4-dinitrotoluene, the primary vapour 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.

Their technology is inspired by the biological design and microscale size of the canine olfactory mucus layer, which absorbs and then concentrates airborne molecules.

"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 unparallelled," said researcher Dr Brian Piorek in a statement.

A microscale channel of liquid absorbs and concentrates the molecules by up to six orders of magnitude.

Once the vapour molecules are absorbed into a 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.

"The technology could be used to detect a very wide variety of molecules. The applications could extend to certain disease diagnosis or narcotics detection, to name a few," said Meinhart.