Portable, accurate, and highly sensitive devices as sensitive as a dog’s nose will be able to sniff out vapors from explosives and other substances and it could become as commonplace as smoke detectors in public places.
A detector that uses microfluidic nanotechnology to mimic the biological mechanism behind canine scent receptors is now in development, said researchers at University of California, Santa Barbara (UCSB), led by professors Carl Meinhart of mechanical engineering and Martin Moskovits of chemistry.
The device is highly sensitive to trace amounts of certain vapor molecules, and able to tell a specific substance apart from similar molecules.
“Dogs are still the gold standard for scent detection of explosives,” Meinhart said. “But like a person, a dog can have a good day or a bad day, get tired or distracted. 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.”
The key to the technology, Meinhart said, is in the merging of principles from mechanical engineering and chemistry.
The device can detect airborne molecules of a chemical called 2,4-dinitrotoluene, the primary vapor emanating from TNT-based explosives, the researchers said. The human nose cannot detect such minute amounts of a substance, but “sniffer” dogs have long been able to track these types of molecules. Their technology comes from 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 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 a patent and has an exclusive license with to SpectraFluidics, a company Piorek co-founded in 2008 with private investors.
Packaged on a fingerprint-sized silicon microchip and fabricated at UCSB’s cleanroom facility, the underlying technology combines free-surface microfluidics and surface-enhanced Raman spectroscopy (SERS) to capture and identify molecules.
A microscale channel of liquid absorbs and concentrates the molecules by up to six orders of magnitude. Once the vapor molecules absorb into the microchannel, they interact with nanoparticles that amplify their spectral signature when excited by laser light. A computer database of spectral signatures identifies the captured molecule.
“The device consists of two parts,” Moskovits said. “There’s a microchannel, which is like a tiny river that we use to trap the molecules and present them to the other part, a mini spectrometer powered by a laser that detects them. These microchannels are twenty times smaller than the thickness of a human hair.”
“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.”