evacuated in a repeated cycle exposing the sensor initially under reduced pressure to ambient air rapidly draws analyte vapor into the sensor accelerating and driving vapor molecules into the polymer film coated on top of the saw device the saw sensor frequency signal is monitored during the cyclical operations exposure to an uncalibrated nerve agent simulant dimethylmethylphosphonate dmmp vapor source for approximately 0 5 seconds during the sensor exposure to ambient air results in a rapid response providing 90 of the total signal response within approximately 0 2 seconds after the vapor source is removed the signal recovery is accelerated by sweeping out relatively volatile vapors with a flow through purging step immediately following the flow through purging the evacuation is applied first to remove the volatile species and then the flow through purging is used to remove the non volatile species as they are u201c stickier u201d than the volatile species an increase in signal response kinetics for chemical warfare agents of approximately 1 2 orders of magnitude can be established with the pressure modulated pneumatics in order to optimize the signal response and recovery kinetics a pneumatic configuration shown in fig3 was designed with a timing diagram shown in fig4 recovery time of the fig3 flush embodiment as compared to the fig1 basic embodiment is greater than about 4 times i e recovery time for the basic embodiment shown in fig1 is typically 3 5 seconds and that for the fig3 flush embodiment is typically less than 1 second the cause and effect of various events during a typical cycle with the flush embodiment shown in fig3 is illustrated in fig4 data collected.