Patent ID: 7528367
Filing Date: 2009-05-05
Classification: G01N

Abstract:
1. An ion mobility spectrometer, comprising: an inlet for receiving a sample to be tested for the presence of at least one substance of interest; an ionization chamber having an upstream end communicating with the inlet and a downstream end; a drift chamber having an upstream end communicating with the downstream end of the ionization chamber and a downstream end opposed to the upstream end thereof; a collector electrode in proximity to the downstream end of the drift chamber for collecting ions passing through the drift chamber; first and second grid electrodes lying substantially in first and second planes aligned substantially parallel to one another substantially at an interface between the downstream end of the ionization chamber and the upstream end of the drift chamber so that the second grid electrode is between the first grid electrode and the collector electrode; and a controller for applying a slight potential bias to the first grid electrode relative to the second grid electrode and walls of the ionization chamber during accumulation phase for accumulating ions between the first and second grid electrodes, the controller further being operative for applying a pulse to the first grid electrode for accelerating ions accumulated between the first and second grid electrodes into the drift chamber and towards the collector electrode.