Sensor apparatus and method for use with gas ionization systems

• US 9,953,818 B2
• Filed: 06/24/2016
• Issued: 04/24/2018
• Est. Priority Date: 11/17/2011
• Status: Active Grant

• Current Assignee: Owlstone Medical Limited
• Original Assignee: Owlstone Medical Limited
• Inventors: Black, Mike, Hart, Matthew, Somerville, John, Taylor, Alastair, Manasi, Iva, Allsworth, Max
• Primary Examiner(s): Stoffa, Wyatt
• Application Number:
  US15/192,665
• Publication Number:
  US 20170004958A1
• Time in Patent Office: 669 Days
• CPC Class Codes: G01N 27/622 Ion mobility spectrometry
• CPC Class Codes: G01N 27/624 Differential mobility spectrometry [DMS]; Field asymmetric-waveform ion mobility spectrometry [FAIMS]
• CPC Class Codes: G01N 27/68 using electric discharge to ionise a gas
• CPC Class Codes: H01J 49/0422 for gaseous samples interfaces to gas chromatographs G01N30/7206
• CPC Class Codes: H01J 49/40 Time-of-flight spectrometers H01J49/36 takes precedence
• CPC Class Codes: H01J 49/403 characterised by the acceleration optics and/or the extraction fields

Abstract

An ion mobility gas detector apparatus including a detector core, an inlet gas path, an exhaust gas path, a source of diluent gas, and at least one or more sensors for measuring temperature, pressure and humidity of gas streams. Further included is a mixing mechanism adapted to mix at least first and second gas streams in response to one or more sensor measurements. A controller is provided for applying drive signals to the detector core.

Claims

1. A method for mixing gas streams in an ion mobility sensor, comprising:

providing a first inlet gas stream to the ion mobility sensor;

providing a second diluent gas stream to the ion mobility sensor;

measuring at least one of temperature, pressure and humidity of each first and second gas stream; and

mixing at least the first and second gas streams in response to measurement of at least the first and second gas streams.

2. The method as recited in claim 1, wherein the ion mobility sensor further includes:

a detector core;

an inlet gas path; and

an outlet gas path.

3. The method as recited in claim 2, further including applying drive signals to the detector core.

4. The method as recited in claim 3, wherein a controller applies the drive signals to the detector core.

5. The method as recited in claim 1, wherein at least one or more sensors are used to measure the at least one of temperature, pressure and humidity of each first and second gas stream.

6. The method as recited in claim 1, wherein a mixing mechanism mixes at least the first and second gas streams in response to the measurement of at least the first and second gas streams.

7. The method as recited in claim 5, wherein the ion mobility sensor further includes a detector core, and wherein the at least one or more sensors includes a humidity sensor positioned in a gas flow path connected in parallel with the detector core whereby at least a portion of inlet gas passes over the humidity sensor.

8. The method as recited in claim 1, wherein the ion mobility sensor is a Field Asymmetric Ion Mobility Spectrometry (FAIMS) detector.

9. The method as recited in claim 8, wherein the FAIMS detector is adapted and configured to operate in a low power mode to monitor for a chemical event whereby upon detection of a chemical event, the FAIMS detector switches to a higher discrimination mode for further analysis.

10. The method as recited in claim 8, wherein the FAIMS detector includes circuitry adapted and configured to monitor RF waveform parameters for feedback to an RF driver.

11. The method as recited in claim 10, wherein the RF waveform parameters monitored include at least one of peak voltage, peak-to-peak voltage, duty cycle, RF power consumption, and component temperatures.

12. The method as recited in claim 8, wherein the FAIMS detector is adapted and configured to facilitate capture of ions of a selected polarity from a gas stream for interaction with an ion detector tier detecting ions.

13. The method as recited in claim 12, wherein the FAIMS detector is further adapted and configured to provide only one dominant ion polarity in a FAIMS analytical region at a time whereby a single polarity of ions can be selected upstream of the FAIMS analytical region using bias electrodes to create electric fields that separate opposite polarities to prevent an undesired polarity from entering a FAIMS filter.

14. The method as recited in claim 13, wherein the electric fields can be dynamically reversed to select an opposite polarity.

15. The method as recited in claim 8, wherein the FAIMS detector is adapted and configured to scan a spectrum in opposite CV directions for acquiring scan results and to combine the results.

16. The method as recited in claim 12, wherein the FAIMS detector is further adapted and configured to reduce DC charge mirroring by preventing or inhibiting ions of an incorrect polarity from impacting the ion detector and facilitating ions of a correct polarity to reach the ion detector.

17. The method as recited in claim 16, wherein an electric bias is applied between an ionization source and a FAIMS filter inlet and/or between a FAIMS filter outlet and one or more detector electrodes to direct a polarity of ions to a detector region.

18. The method as recited in claim 12, wherein the FAIMS detector is further adapted and configured to generate an electric field downstream of a detector electrode using a separate electrode having an applied voltage for driving ions traveling through detector electrode perforations back onto a back surface of the detector electrode.

19. The method as recited in claim 12, wherein an ion detector electrode is integrated in a package common with a FAIMS filter.

20. The method as recited in claim 12, wherein the FAIMS detector is further adapted and configured such that an electric field is generated in a region between a FAIMS filter and at least one detector electrode to direct ions onto a surface of the at least one detector electrode wherein the electric field is at least partially perpendicular to gas flow.