Patent ID: 7851745

Claim:
A high field asymmetric waveform ion mobility spectrometer (FAIMS), comprising: a first electrode having two non-parallel edges defining therebetween a width that decreases along a length of the first electrode, the first electrode having an approximately flat first electrode surface bounded by the two edges; a second electrode having two non-parallel edges defining therebetween a width that decreases along a length of the second electrode, the second electrode having an approximately flat second electrode surface bounded by the two edges, the second electrode disposed in a spaced-apart facing relationship with the first electrode so as to define an electrode assembly with a space of approximately uniform thicknesses between the first electrode surface and the second electrode surface, the two edges of the first electrode and the two edges of the second electrode cooperating to define two lateral boundaries of the electrode assembly with separation therebetween decreasing along a first direction, the space for supporting during use the transmission of ions through the electrode assembly along the first direction; at least two focusing electrodes including at least one focusing electrode disposed adjacent to each of the two lateral boundaries of the electrode assembly, the separation distance between the at least two focusing electrodes decreasing along the first direction; an electrical contact on at least one of the first electrode and the second electrode for receiving an asymmetric waveform potential and for applying a direct current compensation potential between the first electrode and the second electrode, for establishing an electric field within the space for separating ions according to the FAIMS principle; and, an electrical contact on each one of the at least two focusing electrodes for receiving a direct current electrical potential for directing ions in a direction away from one of the two lateral boundaries and toward a central portion of the space.