Portable Field Sorption Detector for the Detection and Recognition of Chemical Agents

摘要

The use of the piezoelectric sorption sensor, in which an analyte's absorption in a thin surface layer on a piezoelectric vibrator changes its resonant frequency, has been extensively described. In every instance, the chemical selectivity of the device hinges on that of the absorbing layer. In a complex environment, few analytes are so distinctive as to permit this. An alternative approach uses an array of crystals covered with a number of different absorbing layers. These are so thin that they operate in the saturation mode, with different partition coefficients against air, resulting in different frequency shifts for each layer. Experimental results of the demonstrated feasibility of a procedure for providing complete selectivity to quartz piezobalance sensors, by using an array of different sensor layers and pattern recognition, are presented. A portable multichannel correlation piezobalance system which fits neatly in an attache-sized case has been built and operated. A description of the system is presented, as well as field test results. The system has sensitivities well below 1 mu g/1, can be electrically tuned selectively to an arbitrary compound, responds in less than one minute, and can deal with mixed samples via a variety of algorithms. (ERA citation 12:001009)