Methods, apparatus, and system for mass spectrometry

Patent metadata

Field	Value
Publication number	US-9312117-B2
Application number	US-201414268599-A
Country	US
Kind code	B2
Filing date	May 2, 2014
Priority date	Feb 14, 2011
Publication date	Apr 12, 2016
Grant date	Apr 12, 2016

Abstract

A miniature, low cost mass spectrometer capable of unit resolution over a mass range of 10 to 50 AMU. The mass spectrometer incorporates several features that enhance the performance of the design over comparable instruments. An efficient ion source enables relatively low power consumption without sacrificing measurement resolution. Variable geometry mechanical filters allow for variable resolution. An onboard ion pump removes the need for an external pumping source. A magnet and magnetic yoke produce magnetic field regions with different flux densities to run the ion pump and a magnetic sector mass analyzer. An onboard digital controller and power conversion circuit inside the vacuum chamber allows a large degree of flexibility over the operation of the mass spectrometer while eliminating the need for high-voltage electrical feedthroughs. The miniature mass spectrometer senses fractions of a percentage of inlet gas and returns mass spectra data to a computer.

First claim

What is claimed is:

1. A mass spectrometer, comprising:
a vacuum housing defining a vacuum cavity in which a pressure of about 10 −5 mm Hg or less is maintained;
an electrode, disposed within the vacuum cavity and configured to be charged to an electrode potential, to control acceleration of a charged particle propagating through the vacuum cavity;
a digital controller, disposed within the vacuum cavity and in electrical communication with the electrode, to control the electrode potential at the electrode and a heater, in thermal communication with at least one component within the vacuum cavity, to heat the at least one component so as to drive gas off the at least one component.

2. The mass spectrometer of claim 1 , wherein:
the electrode comprises a grid electrode to control a flow of electrons; and
the digital controller is configured to modulate the electrode potential at the grid electrode.

3. The mass spectrometer of claim 2 , further comprising:
signal processing electronics, operably coupled to the digital controller, to process digital controller signals used to modulate the electrode potential at the grid electrode so as to increase a signal-to-noise ratio of the mass spectrometer.

4. The mass spectrometer of claim 3 , wherein the signal processing electronics are configured to process the digital controller signals with synchronous detection signal processing techniques and/or stochastic system identification signal processing techniques.

5. The mass spectrometer of claim 1 , further comprising:
a communications module, disposed within the vacuum cavity and operably coupled to the digital controller, to relay data and/or instructions between the digital controller and at least one electronic component outside the vacuum cavity.

6. The mass spectrometer of claim 5 , wherein the communication module comprises a wireless communications interface configured to transmit and/or receive data and/or instructions via at least one wireless communications channel.

7. The mass spectrometer of claim 5 , wherein the communications module is configured to relay the data and/or instructions via at least one data line fed through at least one wall of the vacuum housing.

8. The mass spectrometer of claim 1 , wherein:
the electrode comprises an electrostatic lens electrode configured to focus a stream of ionized particles; and
the digital controller is configured to control the electrode potential of the electrostatic lens electrode.

9. The mass spectrometer of claim 8 , wherein the electrostatic lens electrode focuses the streams of ionized particles onto at least one aperture to limit dispersion of the stream of ionized particles.

10. The mass spectrometer of claim 9 , wherein the at least one aperture is defined by at least one member formed by a chassis of a mass analyzer.

11. The mass spectrometer of claim 10 , wherein the at least one member comprises a flexure to change a width of the at least one aperture.

12. The mass spectrometer of claim 1 , wherein the heater comprises a network of resistive heating elements disposed on a substrate.

13. A method for mass spectrometry, the method comprising:
(A) maintaining a pressure of about 10 −5 mm Hg or less in a vacuum cavity defined by a vacuum housing;
(B) charging an electrode disposed within the vacuum cavity to an electrode potential so as to control acceleration of a charged particle propagating through the vacuum cavity; and
(C) controlling the electrode potential at the electrode via a digital controller disposed within the vacuum cavity and in electrical communication with the electrode; and (D) heating the at least one component within the vacuum cavity so as to drive gas off the at least one component.

14. The method of claim 13 , wherein:
(B) comprises charging a grid electrode configured to control flow of electrons; and
(C) comprises modulating the electrode potential at the grid electrode.

15. The method of claim 14 , further comprising:
(E) processing digital controller signals used to modulate the electrode potential at the grid electrode to increase a signal-to-noise ratio of the mass spectrometer.

16. The method of claim 15 , wherein (E) comprises processing digital controller signals with synchronous detection signal processing techniques and/or stochastic system identification signal processing techniques.

17. The method of claim 13 , further comprising:
(F) relaying, via a communication module coupled to the digital controller, data and/or instructions between the vacuum cavity and outside of the vacuum cavity.

18. The method of claim 17 , wherein (F) comprises relaying data and/or instructions with a wireless communications interface configured to transmit and/or receive data and/or instructions via at least one wireless channel.

19. The method of claim 17 , wherein (F) comprises relaying data and/or instructions via at least one data line fed through at least one wall of the vacuum housing.

20. The method of claim 13 , wherein:
(B) comprises charging an electrostatic lens electrode to focus a stream of ionized particles; and
(C) comprises controlling an electrode potential of the electrostatic lens electrode.

21. The method of claim 20 , further comprising:
focusing the stream of ionized particles onto at least one aperture to limit dispersion of the stream of ionized particles.

22. The method of claim 21 , wherein the at least one aperture is defined by a chassis of a mass analyzer.

23. The method of claim 22 , further comprising changing a width of the at least one aperture.

24. The method of claim 13 , wherein heating the at least one component comprises heating the at least one component with a heater comprising a network of resistive heating elements disposed on a substrate.

25. A mass spectrometer, comprising:
a vacuum housing defining a vacuum cavity;
an inlet, in fluid communication with the vacuum cavity, to allow introduction of a gaseous sample into the vacuum cavity for mass-spectrometric analysis;
an electron source, disposed within the vacuum cavity, to generate electrons that ionize particles of the gaseous sample to form ions;
a grid electrode, disposed within the vacuum cavity and configured to be charged to a grid electrode potential, to control acceleration of the electrons ionizing the particles of the gaseous sample;
an electrostatic lens system, disposed within the vacuum cavity and comprising:
an electrostatic lens electrode, configured to be charged to an electrostatic lens electrode potential, to focus the ions into an ion beam;
at least one aperture, defined by a mass spectrometer component, to focus the ion beam;
at least one flexure, integral to the mass spectrometer component, to change a width of the at least one aperture;
a digital controller, disposed within the vacuum cavity and in electrical communication with the grid electrode and/or the electrostatic lens electrode, to control and/or modulate the grid electrode potential and/or to control the electrostatic lens electrode potential; and a heater, in thermal communication with at least one component within the vacuum cavity, to heat the at least one component so as to drive gas off the at least one component.

Assignees

• Massachusetts Inst Technology
• Massachusetts Inst Technology

Inventors

• Hunter Ian W
• Hemond Brian
• Hemond Harold F

Classifications

• H01J49/30 Primary

  using magnetic analysers {, e.g. Dempster spectrometer} · CPC title

• H01J49/0013 Primary

  Miniaturised spectrometers, e.g. having smaller than usual scale, integrated conventional components · CPC title

• H01J49/24

  Vacuum systems, e.g. maintaining desired pressures · CPC title

• H01J49/022

  Circuit arrangements, e.g. for generating deviation currents or voltages (regulating electric or magnetic variables in general, e.g. current, magnetic field G05F); Components associated with high voltage supply (high voltage supply per se H02M) · CPC title

• H01J49/147

  with electrons, e.g. electron impact ionisation, electron attachment (H01J49/145 takes precedence) · CPC title