Improved Sensitivity for Explosive Vapours and ICAO Taggents Detection Using Electrochemical (EC) Sensors

Abstract

Improvements in electrochemical (EC) cell design, sample preconcentration, sample desorption, pyrolysis and sample transport have led to significant increases in sensitivity towards explosive detection using electrochemical NO₂ sensors. Our EC sensors have been modified to allow faster sample permeation through the sensor membrane giving sharper response peaks. Sample trapping and preconcentration has been optimized for low concentrations of explosive vapours and ICAO taggents. The trap has a low mass and achieves desorption temperatures in approximately 1/5^th of a second. Pyrolyzation uses an efficient high temperature filament, removed from but in close proximity to the desorber element. Transport of vapours to the detector is through a moisture exchanger and removes any effect of fast sampling from an overly wet or dry environment. Near zero dead volumes in the sensor housing force almost complete transmission of gases through the membrane for detection. Detection limits for most vapours is less than a ppb.