SMART SENSOR SYSTEM FOR TRACE ORGANOPHOSPHORUS AND ORGANOSULFUR VAPOR DETECTION EMPLOYING A TEMPERATURE-CONTROLLED ARRAY OF SURFACE-ACOUSTIC-WAVE SENSORS, AUTOMATED SAMPLE PRECONCENTRATION, AND PATTERN-RECOGNITION

A smart sensor system for the detection of toxic organophosphorus and toxic organosulfur vapors at trace concentrations has been designed, fabricated, and tested against a wide variety of vapor challenges. The key features of the system are an array of four surface acoustic wave (SAW) vapor sensors, temperature control of the vapor sensors, the use of pattern recognition to analyze the sensor data, and an automated sampling system including thermally desorbed preconcentrator tubes (PCTs). All the electronics necessary to control and operate the various subsystems and to collect and process the data are included in the system. Organophosphorus analytes were detected at concentrations as low as 0.01 mg/m3 in 2 min, and the organosulfur analyte was detected at 0.5 mg/m3 in 2 min. Pattern recognition algorithms correctly classified these analytes at these concentrations and discriminated them for a variety of other organic vapors.