It was just a few months after the horrifying attacks on the World Trade Centre. On 22 December 2001, Richard Reid steps onto American Airlines flight 63 from Paris to Miami. It’s raining outside, and the flight has been delayed. But what was then an annoyance to passengers turned out to be a blessing: Reid’s shoes were packed with plastic explosives, and the rainy weather prevented them from detonating and killing the 200 passengers on board. A burning smell alerted a passenger, Reid was overpowered and currently serves a life sentence in the US. Things have changed quite drastically in airports since the infamous ‘shoe bomber’ was apprehended. X-raying footwear has become mandatory in the US, making airports safer but also causing long queues and substantially increasing the cost of security. “Forcing people to walk barefoot on board would be a lot like Henry IV’s Road to Canossa. On the other hand, the X-ray technology currently used for footwear screening comes with a major price tag. Here, security and cost-cutting are two sides of the same coin,” says Yuri Udalov, Chief Technology Officer and Co-Founder of Eye on Air. Eye on Air received EU funding for the AirBrush (A fast non-intrusive vapour detection system that rapidly identifies explosives in public areas) project in 2018. Their objective: developing and commercialising an ‘electronic sniffing’ technology based on Ion Mobility Spectrometry (IMS). Whilst such technology has already been applied successfully to the detection of explosive traces, it wasn’t sensitive enough for application to shoe scanning. “Our spectrometer differs substantially from existing devices. Unlike regular IMS devices, it detects vapours of explosives instead of traces. Its sensing modules have a drift space of 10 mm, which is an order of magnitude less than regular IMS spectrometers. The device can record the complete ion spectrum within less than a millisecond without any deterioration of the signal, and it can detect explosive masses of less than a pictogram,” Udalov enthuses. The Eye on Air system works as follows: explosive vapours are collected and introduced into the sensing unit. When the expected concentration of energetic materials is low, sampled molecules might initially be collected on a pre-concentrator. Under the influence of an external ionisation source, the molecules of the test sample are ionised. These ions drift in an electric field and land on a collector electrode – an ion current detector. The drift of ions in a neutral gas flow under the influence of an electric field makes it possible to separate ions based on their mobility. “Heavy ions move slower and thus get to the collector electrode later. As a result, ion current is measured as a function of time and the spectrum of ion arrival time can be obtained. AirBrush has a comprehensive database and is able to identify specific explosives by using its sensing unit and tracking the arrival time of each explosive. It is possible to extend the database with the desired list of target materials provided by the customer,” Udalov explains. Eye on Air has already received several purchase orders for its device and is confident that AirBrush will be available in airports in 2020. According to Udalov, an interesting option would be an integration of the device in a security screening portal, where passengers will be simultaneously scanned by microwave or terahertz full-body scanners, metal detectors and a customised version of AirBrush.
AirBrush, vapour detection system, Ion Mobility Spectrometry, explosive, passenger screening, bomb, airport security, terrorism