Patent ID: 8754366
Filing Date: 2014-06-17
Classification: G01N

Abstract:
1. A chemical sensing system comprising: an ionization system operable to ionize sample molecules; a differential mobility cell connected to said ionization system to receive ionized sample molecules therefrom, said differential mobility cell including a plurality of electrodes operable to apply an electric field in said differential mobility cell; a time-of-flight ion-mobility spectrometry system downstream of said differential mobility cell operable to analyze target ions of said ionized sample molecules to produce a time-resolved spectrum of ions, said time-of-flight ion-mobility spectrometry system including first and second ion mobility drift cells configured to detect, respectively, positive and negative ions from said differential mobility cell, wherein said positive ions exiting the differential mobility cell are pulled toward a first ion gate electrode and gated into said first ion mobility drift cell, and said negative ions exiting the differential mobility cell are pulled toward a second ion gate electrode and gated into said second ion mobility drift cell; and a controller in communication with said plurality of electrodes, said controller configured to control said electric field in tune with said target ions of the ionized sample molecules such that said target ions do not become neutralized by contact with an electrode and are permitted to pass through the differential mobility cell to the time-of-flight ion-mobility spectrometry system.