Israeli researchers have developed a nanotechnology-powered sensor that they say “sniffs out” explosives with 100 to 1,000 times more sensitivity than specially trained dogs, like those the Israeli army is using in the Gaza Strip to uncover Hamas tunnels.

The sensor is also more reliable and provides more specific information than dogs or existing technologies, the researchers say. Research on prototypes, published in the journal Nature Communications in June, shows that it is able to identify faint traces of explosives even in air already thick with cigarette smoke.

“I strongly believe our device represents an excellent candidate to fight terrorism and for military uses as well, such as finding explosive sources before the force enters a building,” said Prof. Fernando Patolsky, whose research team at Tel Aviv University’s School of Chemistry conducted the study.

The explosives sensor developed at Prof. Fernando Patolsky's lab at Tel Aviv University. (photo credit: Prof. Fernando Patoslky/Tracense)

The explosives sensor developed at Prof. Fernando Patolsky’s lab at Tel Aviv University. (photo credit: Prof. Fernando Patoslky/Tracense)

Tracense Systems, a start-up security based in Herzliya, Israel, employs the researchers and has provided more than $10 million in funding. The company is testing the sensor with Israeli security forces, with plans to bring it to market next year.

A nose for explosives

A dog’s nose is the most sensitive explosives detector available now. The IDF usually sends dogs to check for booby traps in newly discovered tunnels from Gaza to Israel before troops go in. One of the IDF’s main objectives in Operation Protective Edge has been to destroy the tunnels, which Hamas uses to send terrorists into Israel. At least one dog has been killed.

‘In my experience, when something explodes, you want to be as far away as you can be.’

Dogs may be the IDF’s best friends, but they are not always dependable. Armies and other security forces around the world know from experience that dogs get tired and confused and make mistakes. They have to be rigorously trained, and they cannot report which chemicals they have detected.

In 2009, Patolsky and his team of scientists, mathematicians, and engineers began using nanotechnology to develop a better way of detecting explosives. According to the study, their sensor can identify a variety of explosives at concentrations as low as a few molecules per quadrillion. It works in about 30 seconds from at least four meters away from the source, the study showed.

“This sensor lets you make better decisions from further away,” said Maj. Gen. (Ret.) Arik Yakuel, a former head of the Israel Police bomb squads and a member of Tracense’s advisory board. “And in my experience, when something explodes, you want to be as far away as you can be.”

The prototype operates like this: A small vacuum wand with a filter on the front is used to collect a gas, liquid, or solid sample. The filter is placed in the sensor, which is about the size of three laptops stacked on top of each other. With the push of a button on the sensor’s touchscreen, more than 100 nanowires chemically interact with the sample, doing the actual sensing. The information is then sent as a signal to the sensor’s computer, which analyzes it to create a unique chemical “fingerprint.”

The sensor is modeled on the olfactory or “sense of smell” system, the researchers say.

If the sample’s chemical fingerprint matches a known explosive, the screen turns red. If it does not, the screen turns green. More detailed data, including a list of the detected explosives and the level of confidence of the reading, can be displayed for further analysis. The portable sensor can be powered by battery and cleans itself in seconds.

Safer borders and skies?

In the study, the sensor accurately detected TNT, RDX, PETN, nitroglycerine, HMX (which is used in commercial blasting and military applications) TATP, and HMTD. TATP and HMTD are commonly used in homemade bombs and are difficult to detect using existing technologies. The researchers expect the sensor to work equally well with other types of explosives.

The sensor was not distracted by cigarette smoke, meaning chain-smoking soldiers, and hopefully other chemical interference, will not distort the readings.

The computer chip with nano-features that runs the sensor. (photo credit: Prof. Fernando Patoslky/Tracense)

The computer chip with nano-features that runs the sensor. (photo credit: Prof. Fernando Patoslky/Tracense)

Tracense’s competitors say that while the results of the study are impressive, the real test will come in the field. Norbert Kloepper, the head of the explosives sensors unit at Germany’s Bruker Corporation and a physicist by training, points out that two similar technologies – surface acoustic wave and quartz crystal microbalance – once promised breakthroughs in explosives detection, but they did not work in real-world conditions.

“From what I have seen, the sensitivity of this sensor is very, very impressive,” said Kloepper. “My questions are about how it will behave in real life. Will it work for soldiers in the heat and dust of a roadside checkpoint, for example, and will the company [Tracense] be able to keep developing proper coatings for their nanowires in response to new threats?”

The researchers say their sensor is better not only than dogs but also than the leading explosives-detecting technology in use today. Airports, including Israel’s Ben Gurion International Airport and other public hubs, use ion-mobility spectrometry to screen for explosives and other contraband. If an airport security agent has ever swabbed you or your luggage with a wand, you have seen the system in action.

Like the airport system, the Israeli developed system has the advantage over dogs of not getting tired or thirsty and of being able to identify specific explosives. But it is also five to six orders of magnitude more sensitive, and easier to use, than the airport system, the researchers say. All this could mean less time in security lines and safer travel for passengers, though competitors have their doubts.

“The increased sensitivity, versatility, and high throughput of our sensor will revolutionize explosives screening of passengers,” said Tracense chief executive Ricardo Osiroff, who has a doctorate in engineering. “Not only will it improve detection and reduce false alarms, it will allow effective screening of 100 percent of passengers and their luggage – and that will mean better security.”

Osiroff says the sensor will cost about one third as much as the airport system to buy and operate. He would not provide exact figures. Patolsky and his team are working to expand the sensor for use with other explosives, as well with as illegal narcotics and chemical weapons.