Longitudinal field driven field asymmetric ion mobility filter and detection system

• US 6,512,224 B1
• Filed: 11/12/1999
• Issued: 01/28/2003
• Est. Priority Date: 07/21/1999
• Status: Expired due to Term

• Current Assignee: Charles Stark Draper Laboratory Incorporated
• Original Assignee: Charles Stark Draper Laboratory Incorporated
• Inventors: Miller, Raanan A., Zahn, Markus
• Primary Examiner(s): Anderson, Bruce C.
• Application Number:
  US09/439,543
• Time in Patent Office: 1,173 Days
• Field of Search: 250/286, 250/287, 250/281, 250/282
• US Class Current: 250/286
• CPC Class Codes: G01N 27/624 Differential mobility spectrometry [DMS]; Field asymmetric-waveform ion mobility spectrometry [FAIMS]
• CPC Class Codes: H01J 49/0018 Microminiaturised spectrometers, e.g. chip-integrated devices, Micro-Electro-Mechanical Systems [MEMS]

Abstract

An asymmetric field ion mobility spectrometer with an ionization source for ionizing a sample media and creating ions. An ion filter is disposed in the analytical gap downstream from the ionization source for creating an asymmetric electric field to filter the ions. An ion flow generator for creating an electric field in a direction transverse to the asymmetric electric field and which propels the ions through the asymmetric electric field towards a detector.

Claims

1. An asymmetric field ion mobility spectrometer comprising:

an ionization source for ionizing a sample media and creating ions;

an analytical gap;

an ion filter disposed in the analytical gap downstream from the ionization source, and including a pair of spaced electrodes for creating an asymmetric electric field to filter the ions;

an ion flow generator including a plurality of spaced discrete electrodes insulated from the pair of spaced electrodes for creating an electric field transverse to the asymmetric electric field for propelling ions through the asymmetric electric field; and

an ion detector for sensing ions not filtered by the ion filter.

2. The spectrometer for claim 1 in which the ion detector is proximate the ion flow generator.

3. The spectrometer of claim 2 in which the ionization source is a radiation source.

4. The spectrometer of claim 1 in which the ionization source includes an ultraviolet lamp.

5. The spectrometer of claim 1 in which the ionization source includes a corona discharge device.

6. The spectrometer of claim 1 in which the ionization source includes an electrospray nozzle.

7. The spectrometer of claim 1 in which the ion filter is connected to an electric controller for applying a bias voltage and an asymmetric periodic voltage to the ion filter.

8. The spectrometer of claim 1 in which the ion flow generator includes spaced resistive layers and a voltage applied along each layer to create a longitudinal electric field.

9. The spectrometer of claim 1 in which the ion filter includes a first plurality of discrete electrodes electrically connected to an electric controller which applies an asymmetric periodic voltage to the first plurality of discrete electrodes and in which the ion flow generator includes a second plurality of discrete electrodes dispersed among the first plurality of discrete electrodes connected to a voltage source which applies a potential gradient along the second plurality of discrete electrodes.

10. The spectrometer of claim 1 in which the analytical gap is enclosed by a housing, the ion filter includes electrodes on an outside surface of the housing and the ion flow generator includes resistive layers on an inside surface of the housing and a voltage is applied along each layer to create a longitudinal electric field.

11. The spectrometer of claim 1 in which the ion filter and the ion flow generator are combined and include a series of discrete conductive elements each excited by a voltage source at a different phase.

12. The spectrometer of claim 1 in which the ion filter is connected to an electric controller for applying a traveling wave voltage.

13. An asymmetric field ion mobility spectrometer comprising:

an ionization source for ionizing a sample media and creating ions;

an analytical gap enclosed by a housing;

an ion filter disposed in the analytical gap downstream from the ionization source, and including electrodes on an inside surface of the housing for creating an asymmetric electric field to filter the ions;

an ion flow generator including electrodes proximate but insulated with respect to the ion filter electrodes for creating an electric field transverse to the asymmetric electric field for propelling ions through the asymmetric electric field; and

an ion detector for sensing ions not filtered by the ion filter.

14. The spectrometer of claim 13 in which the ion detector includes electrodes on an inside surface of the housing proximate the ion filter and the ion flow