Amplifying Fluorescent Polymer Arrays for Chemical Detection of Explosives

Abstract

Amplifying fluorescent polymers developed by collaborators at the Massachusetts Institute of Technology (MIT) have been integrated into a handheld sensor platform capable of detecting single femtogram masses of vapour-phase nitroaromatic explosives in real-time. This sensor, known as Fido, was originally developed under the Defense Advanced Research Projects Agency (DARPA) Dog’s Nose program. During field tests against buried landmines, the sensor has demonstrated the ability to detect trace levels of vapours of nitroaromatic explosives emanating from landmines. The sensor utilizes amplification of fluorescence quenching as a transduction mechanism for detection of nitroaromatic explosives and other closely related compounds. Earlier Fido prototypes utilized a single band of amplifying polymer deployed inside a capillary waveguide to form the sensing element of the detector. A new prototype has been developed that incorporates multiple, discrete bands of different amplifying polymers deployed in a linear array inside the capillary. Vapour phase samples are introduced into the sensor as a sharp pulse via a gated inlet. As the vapour pulse is swept through the capillary by flow of a carrier gas (air), the pulse of analyte encounters the bands of polymer sequentially. If the sample contains nitroaromatic explosives, the bands of polymer will respond with a reduction in emission intensity proportional to the mass of analyte in the sample.