Platform for field asymmetric waveform ion mobility spectrometry with ion propulsion modes employing gas flow and electric field

A method for separation, characterization, and/or detection of ions using differential ion mobility spectrometry or FAIMS, comprising:

• simultaneously applying a longitudinal electric field and a gas flow to move ions through the analytical gap of a FAIMS stage, wherein:
• (i) said gas flow is directed along the ion path through the analytical gap and said electric field pulls ions back toward the source thereby increasing discrimination against more mobile species compared to the flow-only regime and preventing those with mobility above a selected threshold from passing through the analytical gap;
• or
• (ii) the flow and the field are both directed along the ion path through the analytical gap thereby decreasing discrimination against more mobile species compared to the flow-only regime;
• or
• (iii) the field is directed along the ion path through the analytical gap and said flow pulls ions back toward the source thereby increasing discrimination against less mobile species compared to the field-only regime and preventing those with mobility below a selected threshold from passing through the analytical gap;
• and
• wherein the field is time-dependent and the gas flow is adjusted relative to the field intensity to minimize mobility-based discrimination over the desired mobility range.