US Patent 7718960 Ion mobility spectrometer and ion-mobility-spectrometry/mass-spectrometry hybrid spectrometer

A low-cost and high-ion-transmission-ratio ion-mobility spectrometry filter, including an ion source, a first drift region in which a gas flow direction and a DC electric-field direction are opposite to each other, a second drift region in which a gas flow direction is provided, the gas flow direction being different from the gas flow direction in the first drift region, and being opposite to a DC electric-field application direction in the second drift region, an intermediate region having an electric field for causing ions to travel between the first drift region and the second drift region, and a detector for detecting ions which have passed through the first drift region and the second drift region.