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Let Us Spray: Low-Cost Explosive Sensor

NCJ Number
Law Enforcement Technology Volume: 37 Issue: 2 Dated: February 2010 Pages: 56,58,61
Douglas Page
Date Published
February 2010
5 pages
This article describes two emerging technologies for detecting explosives and assesses two existing technologies used for this purpose.
Researchers at the University of California-San Diego have devised a simple new spray-on film that could one day allow airport security, police, and hazardous material teams to quickly and accurately screen vehicles, passengers, luggage, and cargo for traces of nitrogen-based explosive residue. Airport screeners would apply a very thin spray of fluorescent polymer film on a suspect surface to reveal the presence of dangerous chemicals such as nitroglycerin. Contaminated fingerprints leave dark shadows on the film, which glow blue under ultraviolet light. Incriminating traces are revealed as soon as the solution dries, typically within 30 seconds. Another new way to detect explosives has been developed at Oak Ridge National Lab. Researchers have developed what they believe to be a more reliable miniature explosive sensor technology. It provides a way to mass produce miniature explosive sensors less likely to cause false alarms. This effort may one day make it possible to provide more effective bomb protection for infrastructure assets and public-assembly venues. The Oak Ridge research has found a different way to detect explosives based on the physical properties of their vapors. The sensor uses a micromechanical concept called a microfabricated bridge that can be electronically heated from room temperature to 500 degrees Celsius in 50 milliseconds. During this heating process, absorbed explosive molecules are burned, melted, and evaporated. These are just two of a number of airport explosive-detection technologies that have emerged in the past decade. This article concludes with descriptions and assessments of two existing explosive detection systems: backscatter systems that use X-rays when the primary application is scanning humans, and transmission X-rays that screen vehicles and shipping containers.


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