CHAMPAIGN, Ill. University of Illinois chemists have developed a simple sensor to detect an explosive used in shoe bombs. It could lead to inexpensive, easy-to-use devices for luggage and passenger screening at airports and elsewhere.
Triacetone triperoxide (TATP) is a high-powered explosive that in recent years has been used in several bombing attempts. TATP is easy to prepare from readily available components and has been difficult to detect. It defies most standard methods of chemical sensing: It doesn't fluoresce, absorb ultraviolet light or readily ionize.
The few methods available to screen for TATP aren't feasible for on-the-ground use in airports, as they require large, expensive equipment, extensive sample preparation, or relatively high concentrations of TATP in solid or liquid form. There is no simple way to detect TATP vapor.
Kenneth Suslick, the Schmidt Professor of Chemistry at the U. of I., and postdoctoral researcher Hengwei Lin have developed a colorimetric sensor array that can quantitatively detect even very low levels of TATP vapor down to a mere 2 parts per billion. They wrote about their findings in an article published in the Journal of the American Chemical Society.
To create the sensor array, the researchers print a series of 16 tiny colored dots each a different pigment on an inert plastic film. A solid acid catalyst breaks down TATP into detectable components that cause the pigments to change color, like litmus paper.
Each pigment changes colors depending on the concentration of TATP in the air. The array is digitally imaged with an ordinary flatbed scanner or an inexpensive electronic camera before and after exposure to the air.
"Imagine a polka-dotted postage stamp sensor that can sniff out the shoe-bomber explosive simply by using a digital camera to measure the changing colors of the sensor's spots," Suslick said. "The pattern of the color change is a unique molecula
|Contact: Liz Ahlberg|
University of Illinois at Urbana-Champaign