Search

EP-4736216-A2 - ELECTRODE FOR SPECTROMETER

EP4736216A2EP 4736216 A2EP4736216 A2EP 4736216A2EP-4736216-A2

Abstract

The present disclosure relates to an electrode for a spectrometer, in particular, an electrode for an ion gate and/or ion modifier for a spectrometer, such as an ion mobility spectrometer. An aspect of the disclosure provides an electrode for providing a Tyndall-Powell gate structure, the electrode comprising: a conductive structure comprising a hexagonal lattice and a frame around the hexagonal lattice, wherein the hexagonal lattice is planar and the frame is configured to provide additional support to the hexagonal lattice.

Inventors

  • Atkinson, Jonathan R
  • SWALLOW, Phil

Assignees

  • Smiths Detection-Watford Limited

Dates

Publication Date
20260506
Application Date
20240627

Claims (20)

  1. 1. An electrode for providing a Tyndall-Powell gate structure, the electrode comprising: a conductive structure comprising a hexagonal lattice and a frame around the hexagonal lattice, wherein the hexagonal lattice is a planar structure defining a plane and the frame is configured to provide additional support to the hexagonal lattice, wherein: the frame has a thickness perpendicular to the plane defined by the hexagonal lattice which is greater than a thickness of the hexagonal lattice perpendicular to the plane defined by the hexagonal lattice.
  2. 2. The electrode of claim 1 , wherein: the frame and the hexagonal lattice are unitary.
  3. 3. The electrode of claim 2, wherein: the frame and the conductive structure substantially consist of a metal suitable for electrodeposition.
  4. 4. The electrode of any of claims 1 to 3, wherein: the conductive structure comprises conductive struts which form the hexagonal lattice wherein the conductive struts have a width of between 0.080 mm to 0.005 mm in a direction parallel to the hexagonal lattice;
  5. 5. The electrode of any of claims 1 to 4, wherein: the conductive structure comprises conductive struts which form the hexagonal lattice wherein the conductive struts have a thickness of between 0.080 mm to 0.005 mm in a direction perpendicular to the hexagonal lattice.
  6. 6. The electrode of any of claims 1 to 5, wherein: the frame comprises a plurality of frame locator features configured to engage a respective plurality of holder locator features on a holder for holding the electrodes.
  7. 7. The electrode of claim 6, wherein: engagement of the frame locator features of each electrode with the holder locator features arranges the conductive structure of the first electrode parallel to the conductive structure of the second electrode.
  8. 8. The electrode of claim 7, wherein: engagement of the frame locator features of each electrode with the holder locator features aligns the hexagonal lattice of the first electrode with the hexagonal lattice of the second electrode in a direction perpendicular to the hexagonal lattice of each electrode.
  9. 9. The electrode of any of claims 7 to 8, wherein: any of: at least one of the frame locator features comprises a hole and at least one of the holder locator features comprises a peg configured to fit the hole; and, at least one of the holder locator features comprise a hole and at least one of the frame locator features comprises a peg configured to fit the holes.
  10. 10. The electrode of any of claims 6 to 9, wherein: the frame locator features are disposed around the frame to provide a plurality of frame locator features wherein the mean horizontal position and/or mean vertical position of the plurality of frame locator features is located less than a predetermined distance from the centre of the hexagonal lattice, wherein the predetermined distance is based on a width of the conductive struts in a direction parallel to the hexagonal lattice.
  11. 11. An apparatus comprising at least two electrodes according to any of claims 6 to 9, wherein the frame locator features are positioned such that when the frame locator features are located on holder locator features the conductive struts of the respective hexagonal lattice are aligned.
  12. 12. A Tyndall-Powell ion gate comprising: a first electrode and a second electrode, wherein each of the first electrode and the second electrode comprises: a conductive structure comprising a hexagonal lattice wherein the hexagonal lattice is planar; a holder configured to hold the first electrode relative to the second electrode so that the planar hexagonal lattice of the first electrode is: parallel to the planar hexagonal lattice of the second electrode; and, spaced from the second electrode by an electrode spacing.
  13. 13. The Tyndall-Powell ion gate of claim 12, comprising: a first electrode voltage circuit configured to vary a voltage of the first electrode; and, a second electrode voltage circuit configured to vary a voltage of the second electrode; wherein the first electrode volage circuit and the second electrode volage circuit are configured to control a barrier voltage between the first electrode and the second electrode by varying the voltage of the first electrode and the voltage of the second electrode thereby to control passage of ions through the hexagonal holes of the electrodes of the ion gate.
  14. 14. The Tyndall-Powell ion gate of claim 13, wherein: the first electrode volage circuit and the second electrode volage circuit are configured to provide a modification voltage between the first electrode and the second electrode by varying the voltage of the first electrode and the voltage of the second electrode thereby to modify ions disposed between the first electrode and the second electrode.
  15. 15. The Tyndall-Powell ion gate of claim 14, wherein: each of the first electrode and the second electrode comprise a frame configured to provide additional support to the hexagonal lattice.
  16. 16. The Tyndall-Powell ion gate of any of claims 12 to 15, wherein: the frame of each electrode comprises a plurality of frame locator features configured to engage a respective plurality of holder locator features on a holder for holding the electrodes.
  17. 17. The Tyndall-Powell ion gate of claim 16, wherein: engagement of the frame locator features of each electrode with the holder locator features arranges the conductive structure of the first electrode parallel to the conductive structure of the second electrode.
  18. 18. The Tyndall-Powell ion gate of claim 17, wherein: engagement of the frame locator features of each electrode with the holder locator features aligns the hexagonal lattice of the first electrode with the hexagonal lattice of the second electrode in a direction perpendicular to the hexagonal lattice of each electrode.
  19. 19. The Tyndall-Powell ion gate of any of claims 12 to 18, wherein: the first electrode and the second electrode are aligned so that the difference in alignment between conductive elements of the first electrode and conductive elements of the second electrode is less than the width of the conductive elements in a direction parallel to the hexagonal lattice of each electrode.
  20. 20. The Tyndall-Powell ion gate of any of claims 12 to 19, wherein: the holder comprises a spacer disposed between the first electrode and the second electrode.

Description

ELECTRODE FOR SPECTROMETER Field of the invention The present disclosure relates to an electrode for a spectrometer, in particular, an electrode for an ion gate and/or ion modifier for a spectrometer, such as an ion mobility spectrometer. Background Ion mobility spectrometers (IMSs) are used to make determinations of substances in a sample. The sample is vaporised and ionised (e.g. by an ionisation source) and then selectively admitted to a drift chamber by an ion gate. Admitted ions in the drift chamber are moved by drift electrodes against a drift gas of known characteristics until the ions reach a detector at an end of the drift chamber. The time-of-flight (TOF) of the ions (i.e. the time taken for the ions to travel from the ion gate to the detector) is indicative of the mobility of said ion. Ions having different characteristics (e.g. mass and shape) have different mobilities in the drift tube and so a determination of the ions in the sample can be made based on said mobilities. Tyndall-Powell ion gates are a specific type of ion gate for use in IMSs which are typically chosen fortheir relative ease of construction. However, typically Tyndall-Powell ion gates often sacrifice ion transmission (i.e. the relative proportion of ions which can pass through the gate) in comparison to other gate designs. Therefore, IMSs with a Tyndall-Powell ion gate often sacrifice sensitivity due to the relatively poor transmission of ions therethrough. Bradbury-Neilson ion gates are an alternative to Tyndall-Powell ion gates. Bradbury-Nielson ion gates have two electrodes spaced in a direction of travel of ions passing therethrough (e.g. a spacer may be disposed between the two electrodes). In examples, the two electrodes may have approximately the same position along the direction of travel of ions (e.g. they may be aligned in the direction of travel of ions). Bradbury Nielson ion gate have two main drawbacks which are not present in Tyndall-Powell ion gates. A first drawback is that, Bradbury-Nielson ion gates have an open area (e.g. the area of the gate through which ions can pass) which typically provides reduced ion transmission compared to a comparable Tyndall-Powell ion gate which may comparatively reduce the sensitivity of a detector of an IMS. A second drawback is that, when a Bradbury-Nielson ion gate is closed, electric field lines around the gate cause a region devoid of ions to form, called the ‘depletion region’. When the Bradbury-Nielson ion gate is then subsequently opened, ions must traverse the depletion region before they can pass through the gate. This effectively extends the ‘cutting width’ of the gate, and reduces the number of ions which can pass through the gate during the short period of time for which it is open. Summary Aspects of the invention are as set out in the independent claims and optional features are set out in the dependent claims. Aspects of the invention may be provided in conjunction with each other and features of one aspect may be applied to other aspects. An aspect provides an electrode for providing a Tyndall-Powell gate structure, the electrode comprising: a conductive structure comprising a hexagonal lattice and a frame around the hexagonal lattice, wherein the hexagonal lattice is planar and the frame is configured to provide additional support to the hexagonal lattice. The frame may be configured to provide additional support to the hexagonal lattice, which may advantageously permit a hexagonal lattice with a greater open area (e.g. which may require additional support from a frame) to be provided in comparison to a hexagonal lattice with a comparatively less open area (e.g. which may not require additional support from a frame). Accordingly, a hexagonal lattice with a comparatively greater open area (e.g. a greater ratio of open area to closed area of the lattice) may be provided which may improve ion transmission past the electrode (e.g. through the open areas). For example, a hexagonal lattice with a greater open area may not be self-supporting (e.g. the hexagonal lattice may not be able to retain a planar shape without the additional support provided by a frame). The frame may have a thickness perpendicular to the hexagonal lattice which is greater than a thickness of the hexagonal lattice. Accordingly the frame may be comparatively more rigid (e.g. than the hexagonal lattice which may advantageously, permit the frame to provide additional support to the hexagonal lattice. Tyndall-Powell ion gates may not suffer from the drawbacks of Bradbury-Nielson ion gates. For example, Tyndall-Powell ion gates may not have a significant depletion region, because electric field lines around the electrode may remain substantially parallel which results in ion paths remaining parallel. When a Tyndall-Powell ion gate is opened, there may be ions in very close proximity to the gate electrode (i.e. because there is no or a very small depletion region) which may, for the same open period