Nanotech device detects explosives

A new device that mimics the highly sensitive scent receptors found in dogs has been created to recognize the vapors from explosives and other substances. Researchers at the University of California, Santa Barbara (UCSB) have designed a portable, accurate, and highly sensitive detector that uses microfluidic nanotechnology to mimic the biological mechanism involved in canine scent receptors.The team, led by professors Carl Meinhart of mechanical engineering and Martin Moskovits of chemistry, developed a device that is both highly sensitive to trace amounts of certain vapour molecules, and able to tell a specific substance apart from similar molecules.The device will be key in the control and identification of explosives as it can detect airborne molecules of 2,4-dinitrotoluene, the primary vapor that emanates from TNT-based explosives. The technology is inspired by the biological design and microscale size of the canine olfactory mucus layer, which absorbs and then concentrates airborne molecules and allows ‘sniffer’ dogs to track them.

"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," says Professor Carl 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." The technology involved 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 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 then identifies what kind of molecule has been captured. "The device consists of two parts," explains Moskovits. "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 new device could become as commonplace as smoke detectors in public places as it is packaged on a fingerprint-sized silicon microchip. It is also not limited to the detection of explosives: "The technology could be used to detect a very wide variety of molecules," explains Professors Carl Meinhart. "The applications could extend to certain disease diagnosis or narcotics detection, to name a few." The specificity and sensitivity of the device are currently unparalleled as it is capable of real-time detection and identification of certain types of molecules at concentrations of 1 ppb or below.