WO2022117694A2

WO2022117694A2 - Flexible multiple ion detector system

Info

Publication number: WO2022117694A2
Application number: PCT/EP2021/083874
Authority: WO
Inventors: Silke Seedorf; Michael Deerberg; Michael Krummen; Ronald Seedorf; Henning Wehrs
Original assignee: Thermo Fisher Scientific (Bremen) Gmbh
Priority date: 2020-12-04
Filing date: 2021-12-02
Publication date: 2022-06-09
Also published as: WO2022117694A3; DE212021000516U1

Abstract

A detector support system (1) for a mass spectrometer, such as a magnetic sector mass spectrometer, comprises: - a base (10), - at least two movable detector supports (20), - a drive unit for moving the movable detector supports relative to the base, - a first electrical connection unit (31) provided on each movable detector support, - at least one second electrical connection unit (32) provided on the base, and - flexible electrical connection elements (30) extending between each first electrical connection unit (31) and the at least one second electrical connection unit (32). The flexible electrical connection elements (30), which are offset so as to avoid entanglement, may comprise a relatively narrow signal conductor and wider shielding conductors.

Description

Flexible Multiple Ion Detector System

Field of the invention

The present invention relates to flexible electrical connections to moveable ion detectors in mass spectrometers, in particular in magnetic sector mass spectrometers. The present invention also relates to a flexible electrical connection element arranged for electrically connecting movable ion detectors in a mass spectrometer, to a detector support system for a mass spectrometer in which such flexible electrical connection elements may be utilized, and to a mass spectrometer provided with at least one such flexible electrical connection element and/or detector support system.

Background of the invention

Mass spectrometers may have a magnetic or an electric (also known as electrostatic) sector unit, or a combined magnetic and electric sector unit, to separate ions in space. Ions passing through a magnetic sector unit have a curved trajectory, the radius of the curvature depending on their respective m/z (mass-charge) ratio. A detector array, which may also be referred to as multicollector array, is typically used to detect the ions having different m/z ratios at different positions in the focal plane of the mass analyzer, each collector of such an array constituting a detector for a particular ion type.

In order to be able to optimally detect ions having different m/z ratios, at least some of the collectors of a multi-collector array may be movably arranged so that their positions can be adapted to the particular ions that are to be detected. The positions of the detectors are related to the dispersion of the isotopes. The Thermo Scientific™ Neptune™ series of mass spectrometers, for example, comprises a set of ion detectors of which the positions can be adapted to correspond with the locations of the ions to be detected.

United States patent US 10,867,780 (Thermo Fisher Scientific & University of Bristol) discloses a mass spectrometer which comprises a sector field mass analyser and an ion multi-collector array having a plurality of ion detectors for detecting a plurality of different ion species in parallel and/or simultaneously. The disclosed mass spectrometer has a central stationary detector platform and eight movable detector platforms, each detector platform carrying a Faraday cup and at least one ion counting detector. This allows the detectors to be very precisely positioned on the trajectories of the ion species. In a detector array, each detector must be electrically connected to electronic circuits for processing the signals produced by the detectors. This involves providing electrical leads between the movable detectors and a fixed electrical connection. However, such electrical leads may cause several problems.

The electrical leads may cause the detector signals to deteriorate due to secondary electrons and stray ions. That is, secondary electrons released by the impact of ions on the detectors may hit an electrical lead and disturb the detector signal. Ions that bounced off a detector or secondary ions released by the impact of an ion may also reach an electrical lead and cause a disturbance. Such disturbances can be prevented by a metal shielding, but that would make the electrical leads stiffer. Because of the high precision and accuracy requirements, in particular for isotope ratio measurements, the disturbances induced by any secondary electrons and stray ions have to be in the range of IO^-6 of the major ion beam (e.g. 1 ppm), or smaller.

Vibrations may introduce further disturbances of the detector signal. As a result of the small movements of the leads due to the vibrations, any disturbance signals induced in the electrical leads will vary in time and thus produce additional artifacts.

The electrical leads may hinder the movements of the detectors or cause a detector to move from its intended position. That is, the stiffness of the electrical leads may cause them to resist the movement of the detectors. In addition, relatively stiff leads will have a large bending radius and will thus require more space.

It is important that the electrical leads leading to the movable detectors do not get entangled. This is especially true for detectors which can move over a relatively wide range, such as 10 cm or more. Any entanglement of the electrical leads can cause both mechanical resistance and electrical disturbances.

Summary of the invention

It is an object to provide a detector support system for a mass spectrometer having electrical connections with movable detectors, which system minimizes the amount of disturbances of the detector signals. Accordingly, the invention provides a detector support system for a mass spectrometer, the detector support system comprising: a base, at least two detector supports, at least one of which being movable relative to the base, a drive unit for moving the at least one movable detector support, a first electrical connection unit provided on each detector support, at least one second electrical connection unit provided on the base, and flexible electrical connection elements extending between each first electrical connection unit and the at least one second electrical connection unit, wherein the flexible electrical connection elements each have a length which extends substantially parallel to a plane defined by the base and a width which extends substantially perpendicularly to the plane defined by the base, and wherein the flexible electrical connection elements extending from adjacent first electrical connection units are offset relative to each other in the direction of their widths so as to avoid overlap.

By providing flexible connection elements which extend over at least part of their lengths approximately parallel to the plane of the base and have a width which is approximately perpendicular to the plane of the base, the connection elements can be flexible in the plane of the base yet relatively stiff in the direction perpendicular to the plane of the base. The flexible electrical connection elements can be substantially planar and can define a plane which is substantially perpendicular to the base.

In some embodiments the base will be substantially planar, but this is not essential and a non-planar base can be envisaged, for example a curved and/or stepped base. Still, the base may be said to define a certain plane.

In typical embodiments, the base will in use be substantially horizontal. In such embodiments, the flexible electrical connection elements extend substantially horizontally and their widths extend substantially vertically. This arrangement allows the flexible connection elements to adapt easily to horizontal movements of the detector supports while approximately maintaining their substantially vertical positions. It is noted that substantially vertical is meant to include an angle of at least 60° to the horizontal, such as at least 70° or at least 80°, for example 90°, but this angle is not limited to 90° to the horizontal. Similarly, substantially horizontal is meant to include an angle of at most 30° to the horizontal, such as at most 20° or at most 10°, for example 0°, but this angle is not limited to 0°.

The flexible electrical connection elements can be flexible enough so as to avoid any significant mechanical resistance to the movable detector supports, yet stiff enough to avoid getting entangled by bending in the perpendicular (typically the vertical) direction. The detector support system of the invention is insensitive to mechanical vibrations and, due to the flexibility of the connection elements, requires relatively little space.

In some embodiments a single flexible electrical connection element connects each first electrical connection unit, and thus each detector support, with a second electrical connection unit. Although two or more flexible electrical connection elements could be used to connect a single first electrical connection unit with a second electrical connection unit, using a single flexible electrical connection element per detector support minimizes any electrical and/or mechanical disturbances. For the same reason, it is preferred that a single first electrical connection unit is mounted on and/or connected to each detector support.

To avoid touching or entanglement of flexible connection elements of adjacent detector supports, not all flexible connection elements are connected at a similar position to their respective detector supports. In particular, the flexible (electrical) connection elements of adjacent detector supports extend from different positions on their respective first electrical connection unit and are thus offset relative to each other. By providing an offset of the flexible electrical connection elements in the direction of their widths, which typically is approximately the vertical direction, overlap of adjacent flexible electrical connection elements can be avoided, thus avoiding any entanglement of the flexible electrical connection elements and reducing or eliminating interference between flexible electrical connection elements.

When more than two detector supports are provided, they may be arranged in groups of two or more adjacent detector supports. The detector supports of a single detector support system may comprise one, two, three or more groups of detector supports, each group consisting of two, three, four five or more . In some embodiments, the flexible electrical connection elements extending from a group of adjacent first electrical connection units are offset in the direction of their widths so as to provide a step-like arrangement with other flexible electrical connection elements of the group. That is, the flexible connection elements of consecutive detector supports of a group may each have a greater distance relative to a common line than the previous one. The offset may be relative to an edge or side of a detector support, for example.

Accordingly, the first electrical connection units may be arranged in one or more groups of adjacent first electrical connection units, and consecutive flexible electrical connection elements extending from respective first electrical connection units of a group may have an increasing distance relative to a side of each first electrical connection unit so as to constitute a stepped arrangement of flexible electrical connection elements. In the next group, the offset may be such that the stepped arrangement of the first group is repeated, although a mirrored stepped arrangement would also be possible, for example. The detector support system may comprise at least two groups of first electrical connection units. In an embodiment, the detector support system comprises two groups of five detector supports each, in each group the first electrical connection units being offset in the direction of their widths so as to avoid overlap with other flexible electrical connection elements of that group, while allowing overlap with the flexible electrical connection elements of the other group.

The flexible electrical connection elements may have a thickness which is at most l/10^th of their width, in some embodiments at most l/20^th of their width. Conversely, the width of the flexible electrical connection elements may be 10 times their thickness or more, for example 20 times. This relatively large width can provide sufficient stiffness in the vertical direction to maintain the substantially longitudinal extension of the flexible electrical connection elements along the base.

The flexible electrical connection elements may have a width between 2.5 mm and 10 mm, preferably between 4 mm and 6 mm. The flexible electrical connection elements may have a thickness between 0.05 mm and 0.5 mm, preferably between 0.1 mm and 0.3 mm, to provide sufficient flexibility in one direction yet sufficient stiffness in the other direction.

A flexible electrical connection element may comprise a signal conductor and two shielding conductors which extend on either side of the signal conductor over at least part of its length. The shielding conductors, which may extend parallel to the signal conductor, serve to provide shielding against stray electrons and/or ions. To minimize the impact of stray electrons and/or ions hitting the flexible electrical connection element, the signal conductor is preferably relatively narrow. In some embodiments, the signal conductor has a width of less than 0.5 mm, or even less than 0.2 mm, for example 0.1 mm. The signal conductor and each shielding conductor are separated by a spacing. To optimize the effect of the shielding conductors, the spacing may be relatively narrow. Accordingly, the spacing may have a width of less than 0.25 mm, for example between 0.1 mm and 0.2 mm.

A flexible connection element may be provided with a protective layer. The protective layer may comprise a polyimide film, which film may comprise Kapton™.

A flexible connection element may comprise contact areas at both ends, each contact area comprising a conducting surface. The conductive surface serves to provide an electrical contact. In such embodiments, the signal conductor may extend between the contact areas. At least one contact area may at least partially surround a contact opening in the flexible foil. The at least one contact opening may receive a conducting fastening element, such as a metal screw.

A flexible connection element may be provided with an auxiliary opening for fastening the flexible connection element. In some embodiments, the shielding conductors extending from the auxiliary opening along the length of the flexible connection element in one direction only. The signal conductor may deviate from its longitudinal trajectory to pass around the auxiliary opening.

The invention further provides a flexible electrical connection element for electrically connecting movable ion detectors in a mass spectrometer, the flexible electrical connection element comprising: an elongate electrically insulating flexible foil, a first contact area on a first end of the foil and a second contact area on a second end of the foil, each contact area comprising a conducting surface, a signal conductor extending over the foil to electrically connect the first contact area and the second contact area, a first shielding conductor and a second shielding conductor extending on either side of the signal conductor over at least part of its length in the same plane, spaced apart from the signal conductor, and a protective layer covering at least part of the signal conductor and the shielding conductors while leaving the contact areas exposed, wherein the signal conductor has a width of less than 0.5 mm, and wherein the flexible electrical connection element has a width which is at least 10 times its thickness.

By providing an elongate electrically insulating flexible foil which comprises a first and a second contact area at either end, which further comprises a signal conductor electrically connecting the contact areas, an electrical connection can be made using the length of the flexible electrical connection element.

By providing a first shielding conductor and a second shielding conductor extending on either side of the signal conductor over at least part of its length in the same plane, protection against any interference of secondary ions and secondary electrons is achieved. The structure of the flexible electrical connection element of the invention may be referred to as a coaxial cable in 2D, that is, a two-dimensional coaxial cable, as the signal conductor is shielded in the plane of the flexible electrical connection element. By making the width of the signal conductor smaller than 0.5 mm, the likelihood of stray ions and/or electrons hitting the signal conductor is further reduced.

By providing a width of the flexible connection element which is at least 10 times the thickness of the flexible electrical connection element, a sufficient flexibility in one direction and a sufficient stiffness in another, orthogonal direction can be achieved. In particular, such a width provides sufficient stiffness in the plane of the connection elements. In some embodiments, the width of the flexible connection element is at least 20 times its thickness, for example approximately 30 times.

It is noted that the width mentioned above can be the effective width at the location of the shielding elements. The actual width of the connection element may be smaller in parts where the shielding elements are not present, for example near the ends of the connection element, to locally increase its flexibility. The length of the connection element may be an effective length defined by the contact areas, the actual length may be greater if parts of the foil protrude beyond one or more contact areas.

The signal conductor may have a width that is substantially smaller than the width of each of the shielding conductors. In particular, the signal conductor may have a width which is less than 50% of the width of a shielding conductor. In some embodiments, the width of the signal conductor may be less than 25%, more preferably less than approximately 10%. A suitable width of the signal conductor may be less than 0.5 mm, for example a width of between 0.1 mm and 0.2 mm. The spacing between the signal conductor and each shielding conductor may be approximately equal to the width of the signal conductor. In some embodiments, the spacing between the signal conductor and each shielding conductor is between 0.1 mm and 0.2 mm. In some embodiments, the signal conductor has a width of between 0.1 mm and 0.2 mm.

The spacing between the signal conductor and each shielding conductor may be between l/15th and l/100th of the width of the flexible electrical connection elements, preferably between l/25th and l/50th.

The connection element may have a width at the part where the shielding conductors extend which is at least 25 times its thickness, preferably at least 50 times its thickness, more preferably at least 100 times its thickness.

The connection element may further comprise contact areas at both ends, each contact area comprising a conducting surface. At least one of the first contact area and the second contact area at least partially surrounds a contact opening in the flexible foil. In this way, a screw or bolt inserted into the contact opening can contact a contact area and hence the signal conductor.

The protective layer may comprise a polyimide film, preferably Kapton™. The foil may be made of an electrically insulating material and/or is provided with an electrically insulating layer.

The protective layer may leave at least one area of each shielding conductor exposed, the at least one exposed area providing a further contact area. Such a further contact area can be used for connecting the shielding conductor to ground.

An auxiliary opening may be provided in the foil, the first shielding conductor and the second shielding conductor extending on one side of the auxiliary opening only. Such an auxiliary opening may be used to fasten the connection element. An auxiliary opening may not be surrounded by a contact area.

The auxiliary opening may be in the trajectory of the signal conductor, the signal conductor deviating from its trajectory around one side of the opening. In such embodiments, the signal conductor may deviate towards the second shielding conductor, the first shielding conductor preferably extending further towards the auxiliary opening than the first shielding conductor. The auxiliary opening may, for example, be provided on a central longitudinal axis of the connection element. If the signal conductor is also located on the longitudinal axis, the provisioning of the auxiliary opening on the axis without interfering with the signal conductor can be made possible by shaping the signal conductor such that is goes around the auxiliary opening. The trajectory of the signal conductor may extend on one side of the auxiliary opening only to avoid producing a loop with might be susceptible to RF (radio frequency) disturbances.

In embodiments where the signal conductor deviates from its trajectory around one side of the auxiliary opening, the signal conductor may deviate towards the first shielding conductor, the second shielding conductor preferably extending further towards the auxiliary opening than the first shielding conductor. Shortening the first shielding conductor provides space for the signal conductor's path around the auxiliary opening.

At least one shielding conductor may extend over at least 50% of the length of the signal conductor, preferably at least 60%. It is preferred that the shielding conductors extend over that part of the length of the flexible electrical connection elements which extends between a first electrical connection unit provided on a movable detector support and a second electrical connection unit provided on a base of a detector support system. Thus, the shielding conductors extend over that part of the length of the flexible electrical connection elements which is not shielded by any connection units and are therefore exposed to stray ions and electrons.

The signal conductor of a flexible electrical connection element may preferably be straight, at least over the most of its length. In an embodiment the flexible electrical connection elements are substantially straight when not in use. It will be understood that they may be bent during use.

A mass spectrometer comprising a detector support system and/or at least one flexible electrical connection element as described above is also disclosed. The mass spectrometer may further comprise a magnetic sector unit, an electrostatic sector unit, an ion source, and/or a plurality of detectors, at least some of which are movably arranged. At least one detector mounted on a detector support may be a Faraday cup. Detectors mounted on a detector support may be Faraday cups, other detectors or both. Brief description of the drawings

Fig. 1 schematically shows a mass spectrometer comprising a magnetic sector unit.

Fig. 2 shows, in perspective, a detector support system for a mass spectrometer.

Fig. 3 shows, in perspective, the detector support system of Fig. 2 without cover plates.

Fig. 4 shows, in perspective, part of the detector support system of Fig. 2 in more detail.

Fig. 5 shows, in perspective, a first electrical connection unit without a cover.

Fig. 6 shows, in perspective, part of the detector support system of Fig. 2 in more detail.

Fig. 7 shows, in perspective, a second electrical connection unit provided with flexible electrical connection elements.

Figs. 8A to 8C show, in top view, a flexible electrical connection element as used in the detector support system of Fig. 2.

Detailed description of the drawings

A mass spectrometer may comprise an ion source, one or more mass filters and a detector unit. The ion source may be an ICP (inductively coupled plasma) ion source, although other ion sources may also be used, such as an electron impact (El) ion source or a thermal ionization (Tl) ion source. United States patent US 10,867,780, which is hereby incorporated by reference herein, discloses an example of a mass spectrometer comprising a magnetic sector mass filter. The known mass spectrometer comprises an ion source for generating a beam of ions from a sample, a mass filter downstream of the ion source to select ions from the beam by their mass-to-charge ratio (m/z), a collision cell downstream of the mass filter, a sector field mass analyzer downstream of the collision cell and an ion multicollector downstream of the mass analyzer. The ion multicollector comprises a plurality of ion detectors for detecting a plurality of different ion species in parallel and/or simultaneously.

Several types of ion detectors are known, for example Faraday cups, compact discrete dynodes (CDDs) and secondary electron multipliers (SEMs). In some mass spectrometers, a plurality of Faraday cups is combined with one or two other types of ion detectors, the Faraday cups being used for ions occurring in larger quantities (resulting in an ion current) and the other type(s) of ion detectors (typically resulting in ion pulses) being used for ions occurring in smaller quantities.

A mass spectrometer in which the invention may be applied is, by way of example, schematically illustrated in Fig. 1. The mass spectrometer 100 is shown to comprise an ion source 110, a beam focusing unit 120, a magnetic sector unit 130, a detector unit 140, and a detector signal processing unit 150. The ion source 110 may be a plasma source, such as an inductively coupled plasma (ICP) source, or a non-ICP source, such as a filament source. The ion source 110 is arranged for producing an original ion beam 101 which is focused by the beam focusing unit 120 to become a focused ion beam 102. The optional beam focusing unit 120 can comprise suitable ion optics which may be known per se. A mass filter (not shown) may optionally be arranged between the beam focusing unit 120 and the magnetic sector unit 130. The mass spectrometer may optionally further comprise an electrostatic sector unit and/or a 90° deflection unit.

In the magnetic sector unit 130, ions contained in the ion beam 102 may be separated according to their respective masses. Thus, the single focused ion beam 102 entering the magnetic sector unit 130 is split up into multiple ions beams 103 which may reach different detectors of the detector unit 140, allowing ions having different masses to be detected separately. The detector unit 140 produces ion detection signals IS which can be amplified and further processed in the signal processing unit 150, resulting in output signals OS which may include an average detection frequency per ion detector, and hence per ion mass range. Instead of, or in addition to a sector field unit, such as the magnetic sector unit 130, a mass filter unit such as a multipole unit (for example a quadrupole unit) may be used.

An exemplary embodiment of a detector support system for a mass spectrometer is schematically illustrated in Fig. 2. The detector support system 1 is shown to comprise a base 10 on which a detector support mechanism is mounted. The detector support mechanism comprises detector supports 20, guiding rods 21, guiding elements 22, end blocks 23 and connecting bars 24. The end blocks 23 are, in the embodiment shown, mounted on raised parts of the base 10. The ends of the guiding rods 21 are mounted in openings in the end blocks 23. The detector supports 20 and the guiding elements 22 are provided with openings through which the guiding rods 21 can pass, as is shown in more detail in Fig. 4. This allows the detector supports 20 and guiding elements 22 to slide over the guiding elements 22. A connecting bar 24 connects each detector support 20 with a guiding element 22 to provide a unit which can slidably move over the guiding rods 21. It will be understood that the length of the connecting bars 24 determines the distance over which the detector support unit can slide over the guiding rods 21. Each detector support 20 is provided with a mounting element 40 on which one or more detectors, such as a Faraday cup and another type of ion detector, can be mounted. In the embodiment shown, the detector support system 1 comprises ten detector supports 20, arranged in two groups of five detector supports each. A drive mechanism may be provided comprising electrical motors arranged on or under the base 10. Each motor can have a drive wheel contacting a connecting bar 24 so as to be able to individually slide a detector support unit in its desired position. Position sensors may be provided to provide position feedback to a control system controlling the motors. Not all detector supports may be driven by the drive mechanism. Some detector supports may be passive as they may be moved by driven (that is, active) detector supports. Additionally, or alternatively, one or more detector supports may be stationary.

The upstanding walls of the base 10 provide a space which is in the view of Fig. 2 closed off by cover plates 11, which are mounted by mounting bolts 12. In the view of Fig. 3, these cover plates have been removed. It can thus be seen that a first electrical connection unit 31 is mounted on each detector support 20, two second first electrical connection units 32 are mounted on the base 10, and that each group of five first electrical connection units 31 connected to a respective second first electrical connection unit 32 by flexible electrical connection elements 30. Thus, the first electrical connection units 31 move with the detector supports while the second electrical connection unit 32 are stationary, the flexible electrical connection elements 30 providing the electrical connections.

The detector support system 1 shown in Fig. 3 is designed such that identical flexible electrical connection elements may be used for all connections between first electrical connection units 31 and second electrical connection units 32, irrespective of their positions. This reduces the number of different parts required for the detector support system.

A detector support unit is shown in more detail in Fig. 4. The detector support 20 is connected with a guiding element 22 by a connecting bar 24. The guiding element is provided with openings 41 and 42 for accepting the guiding rods (21 in Fig. 3), while the detector support is provided with openings 43 and 44 for this purpose. A first electrical connection unit is, in the embodiment shown, mounted underneath the detector support. A flexible electrical connection element 30 is shown to extend from the first electrical connection unit 31.

The electrical connection unit 31 of Fig. 4 is shown in Fig. 5 without its cover. An end of the flexible electrical connection element 30 is shown to be connected to a pin 45, which provides an electrical connection with a detector mounted on the detector support (20 in Fig. 4). In the example of Fig. 5, the flexible electrical connection element 30 is mounted in the lowest of five possible positions. The flexible electrical connection element 30 may be dimensioned in such a manner that it can be connected to the pin 45 while extending substantially straight from this position while having slack when extending from any of the other four positions. It will be understood that the five possible positions allow the same parts to be used for each detector support of a group of five detector supports (see Fig. 3). It will also be understood that the number of five is provided by way of example and that other numbers of detector supports per group and thus of possible positions with a first electrical connection unit 31 are also possible, such as 2, 3, 4, 6, 7, 8 or more. The first electrical connection unit 31 can at least partially be made of metal to provide a shielding against stray electrons and ions.

Fig. 6 shows an embodiment of a detector support mechanism 2 in perspective view. The detector support mechanism 2 comprises two groups G1 and G2 of detector support units with a detector support 20, a guiding element 22, a connecting bar 24, a (first) electrical connection unit 31 and a flexible electrical connection element 30 each. The flexible electrical connection elements 30 are mounted substantially vertically, that is, their width extends in a vertical plane.

As can be seen in Fig. 6, the flexible electrical connection elements 30 are offset relative to each other so as to provide a stepped arrangement. The width of the flexible electrical connection elements 30 of a group have no overlap, but instead show a spacing. This allows the flexible electrical connection elements 30 to flex when their detector supports 20 are moved while avoiding any mechanical interference between the flexible electrical connection elements, such as entangling. It can be seen that per group, the stepped arrangement is repeated, so as to provide a maximum distance between the flexible electrical connection elements of adjacent groups.

A stationary second electrical connection element 32 is shown in Fig. 7 with part of the casing removed so as to show its interior. As can be seen, the second electrical connection element 32 comprises five pins 52 for providing electrical connections with further electrical devices below the base (10 in Fig. 2). A flexible electrical connection element 30 is connected to each pin 52. Each flexible electrical connection element 30 is mounted to the casing of the second electrical connection element using a fastening strip 55 which is bolted to the casing part, while a pin 51 extends through an opening in each flexible electrical connection element 30.

In the example shown, the topmost flexible electrical connection element 30 extends substantially straight from the fastening strip 55 towards its pin 52, while the other flexible electrical connection elements 30 have slack. Each flexible electrical connection element 30 is shown to have a connection opening 301 for fastening to the corresponding first electrical connection unit (31 in Fig. 6). The second electrical connection unit 32 can at least partially be made of metal to provide a shielding against stray electrons and ions. Fig. 7 makes clear that identical flexible electrical connection elements may be used for all connections between first electrical connection units 31 and second electrical connection units 32, irrespective of their positions. Thus, all flexible electrical connection elements 30 may have the same length.

An embodiment of a flexible electrical connection element 30 is shown in more detail in Figs. 8A-8C. Fig. 8A shows the entire flexible electrical connection element 30, while Figs. 8B and 8C show its ends in more details.

The flexible electrical connection element 30 shown in Fig. 8A comprises a flexible foil, on which a signal conductor is arranged. The signal conductor (300 in Figs. 8B & 8C) extends in the embodiment shown over substantially the full length of the flexible electrical connection element and connects a first contact area Cl at one end with a second contact area C2 at the opposite end. Over part of the length of the signal conductor, a first shielding conductor 321 and a second shielding conductor 322 extend on either side of the signal conductor. The shielding conductors 321 and 322 are arranged on the flexible foil next to the signal conductor and therefore lie in the same plane as the signal conductor. The shielding conductors 321 and 322 are spaced apart from the signal conductor 300 so as to be electrically isolated from the signal conductor. As can be seen, the shielding conductors 321 and 322 are both wider than the signal conductor 300, which is relatively narrow so as to reduce the chances of being hit by ions or electrons. Due to the presence of the shielding conductors 321 and 322, the middle part of the flexible electrical connection element is wider than the end parts. As can be seen in Figs. 5 and 7, the relatively wide middle part is the part which extends between the electrical connection units 31 and 32, while the relatively narrow end parts are the parts which are during use inside the electrical connection units 31 and 32 and therefore require less shielding. Embodiments of the flexible electrical connection element may have a uniform width over substantially its entire length, even if the shielding conductors do not extend over substantially the entire length of the flexible electrical connection element. In such embodiments, the end parts may comprise foil areas which are not covered by the protective layer. However, relatively narrow end parts are preferred as they have a greater flexibility which assists in taking up slack, as shown for example in Fig. 7. Over part of its length, the flexible electrical connection element 30 and hence the flexible conductor 300 can be covered by a protective layer covering at least part of the signal conductor and the shielding conductors while leaving the contact areas exposed. In the embodiment shown, the protective layer is applied in three areas: a first end area 304, a second end area 305 and a middle area 306. The protective layer not only protects the conductors against mechanical damage, but also provides shielding against electrons and ions, and provides electrical insulation.

In a few places the protective layer can be absent, thus leaving one or more conductors exposed: in the contact areas Cl and C2 at the ends of the flexible electrical connection element, exposing contact surfaces 341 and 342 respectively; and in the additional contact areas C3 and C4, where the signal conductor 300 and the shielding conductors 321 and 322 are exposed. The additional contact areas C3 and C4 serve to connect the shielding conductors to ground, or to another suitable electrical voltage. Electrical contacts can be arranged for this purpose in the electrical connection units (31 and 32 in Fig. 3). These electrical contacts can be shaped in such a way that they contact the shielding conductors 321 and 322 while avoiding contact with the signal conductor 300. It can thus be seen that the contact areas Cl and C2 are signal contact areas, while the contact areas C3 and C4 are ground contact areas. When the shielding conductors are connected to (electrical) ground, they may be referred to as grounding conductors and serve to remove any electric charges that may have accumulated on the flexible electrical connection element.

The ground contact area C4 is, in the embodiment shown, provided with an opening 303 for fastening the flexible electrical connection element 30. In the view of Fig. 7, pins 51 are shown which can extend through the fastening openings 303 of the flexible electrical connection elements 30 to define their positions relative to the electrical connection unit 32 and to provide strain relief.

The fastening opening 303 is shown in more detail in Fig. 8B. It can be seen in Fig. 8B that the signal conductor 300 goes around the fastening opening 303, thus deviating at Qfrom its regular straight trajectory. To this end, the second shielding conductor 322 is shortened relative to the first shielding conductor 312, which extends further towards the opening 303, thus maximizing the shielding. The protective layer 306 does not extend over the full length of the shielding conductors 321 and 322, thus leaving the ends of the shielding conductors 321 and 322 exposed to provide the contact area C4. This leaves the signal conductor 300 also exposed. In the embodiment shown, the edge of the protective layer part 306 is pointed towards the opening 303 so as to protect the signal conductor 300 over a greater part of its length. Similarly, the protective layer part 305 is also pointed towards the opening 303 to optimally protect the signal conductor.

The contact area C2 is not covered by the protective layer part 305, thus allowing the electrical contact surface 342 to be contacted. The electrical contact surface 342, which is integral with the signal conductor 300, extends around the fastening opening 302. A flap 332, consisting of foil 330, extends beyond the contact area 342 to facilitate the handling of the flexible electrical connection element. The protective layer part 305 has a pointed edge, pointing towards the fastening opening 302.

As shown in Fig. 8C, the first contact area Cl has a similar structure and comprises a contact surface 341 which surrounds a fastening opening 301. A flap 332 is not present at this end of the flexible electrical connection element but may be provided. The contact area C3 comprises the exposed signal conductor 300 and shielding conductors 321 and 322. As there is no opening in this contact area, the signal conductor 300 has a straight trajectory. In the example of Fig. 8C, the contact area C3 is larger than the contact area C4, leaving larger areas of the conductors exposed. The dimensions of the contact area C3 can be determined by the design of the first electrical connection unit shown in Fig. 5.

In the embodiment shown, the middle protective layer part 306 extends over more than 50% of the length of the flexible electrical connection element, in fact over more than 60%. The protective layer parts 304, 305 and 306 cover most of the surface of the flexible electrical connection element, leaving only the contact areas Cl to C4 exposed. The protective layer may comprise a polyimide, for example Kapton™, optionally combined with acryl. The conductors may be made of copper, for example.

The width of the signal conductor 300 may be between 0.05 mm and 1.0 mm, preferably between 0.05 mm and 0.5 mm, more preferably between 0.1 mm and 0.2 mm, for example approximately 0.15 mm. It is preferred that the signal conductor has a uniform width and is straight over most of its length, although curved signal conductors may also be utilized in some embodiments. The width of a shielding conductor may be at least 1 mm, preferably at least 1.5 mm.

The spacing between the signal conductor and each shielding conductor may be at least 0.1 mm, for example between 0.1 mm and 0.2 mm, but is preferably small relative to the width of the flexible electrical connection element. A spacing of approximately 0.2 mm is preferred. The thickness of the signal conductor and the shielding conductors may be, for example, less than 0.1 mm, preferably less than 0.05 mm, for example between 0.03 mm and 0.04 mm.

The base layer of the flexible electrical connection element is preferably an electrically insulating foil 330 which may be made of a polyimide. A suitable polyimide is Kapton™, although many other polyimides may also be suitable. The foil may have a thickness of less than 0.5 mm, preferably less than 0.1 mm. A thickness of 0.05 mm, for example, has been found suitable.

It has been found that the flexible electrical connection element should have both sufficient stiffness in the direction of its width when it is vertically mounted, and sufficient flexibility in the direction perpendicular to its plane. To this end, a suitable ratio of its thickness and its width assists in meeting these objects. The width can be at least 25 times the thickness, for example 30 times, but preferably not more than 100 times.

The total thickness of the flexible electrical connection element may be less than 0.5 mm, preferably less than 0.2 mm, still more preferably between 0.1 mm and 0.15 mm, for example approximately 0.14 mm. The total width may be, for example, approximately 5 mm, although smaller (for example 3 or 4 mm) or greater (for example 6, 7, 8 or 10 mm) may also be suitable. The small thickness reduces the risk of any air bubbles in the flexible electrical connection element, which would be detrimental to its electrical properties.

The flexible electrical connection element of the invention is highly suitable for use in an ion detector system of a spectrometer and performs much better than a conventional ribbon cable, for example. The detector support system and the flexible electrical connection element of the invention may be designed such that flexible electrical connection elements having identical dimensions can be used.

It will be understood by those skilled in the art that the invention is not limited to the embodiments shown and that many additions and modifications may be made without departing from the scope of the invention as defined in the appending claims.

Claims

1. A detector support system for a mass spectrometer, the detector support system comprising: a base, at least two detector supports, at least one of which being movable relative to the base, a drive unit for moving the at least one movable detector support, a first electrical connection unit provided on each detector support, at least one second electrical connection unit provided on the base, and flexible electrical connection elements extending between each first electrical connection unit and the at least one second electrical connection unit, wherein the flexible electrical connection elements each have a length which extends substantially parallel to a plane defined by the base and a width which extends substantially perpendicularly to the plane defined by the base, and wherein the flexible electrical connection elements extending from adjacent first electrical connection units are offset relative to each other in the direction of their widths so as to avoid overlap.

2. The detector support system according to claim 1, wherein the first electrical connection units are arranged in one or more groups of adjacent first electrical connection units, and wherein consecutive flexible electrical connection elements extending from respective first electrical connection units of a group have an increasing distance relative to a side of each first electrical connection unit so as to constitute a stepped arrangement of flexible electrical connection elements.

3. The detector support system according to claim 2, wherein a group comprises at least two first electrical connection units, preferably five first electrical connection units.

4. The detector support system according to claim 2 or 3, wherein the detector support system comprises at least two groups of first electrical connection units.

5. The detector support system according to any of the preceding claims, wherein a single flexible electrical connection element is connected to each first electrical connection unit.

6. The detector support system according to any of the preceding claims, wherein the flexible electrical connection elements have a thickness which is at most l/10^th of their width, preferably at most l/20^th of their width.

7. The detector support system according to any of the preceding claims, wherein the flexible electrical connection elements have a width between 2.5 mm and 10 mm, preferably between 4 mm and 6 mm.

8. The detector support system according to any of the preceding claims, wherein the flexible electrical connection elements have a thickness between 0.05 mm and 0.5 mm, preferably between 0.1 mm and 0.3 mm.

9. The detector support system according to any of the preceding claims, wherein a flexible electrical connection element comprises a signal conductor and two shielding conductors which extend on either side of the signal conductor over at least part of its length.

10. The detector support system according to claim 9, wherein the signal conductor has a width of less than 0.5 mm, preferably less than 0.2 mm.

11. The detector support system according to claim 9 or 10, wherein the signal conductor and each shielding conductor are separated by a spacing, which spacing preferably is between 0.1 mm and 0.2 mm.

12. The detector support system according to any of the preceding claims, wherein a flexible connection element is provided with a protective layer.

13. The detector support system according to claim 12, wherein the protective layer comprises a polyimide film, the film preferably comprising Kapton™.

14. The detector support system according to any of the preceding claims, wherein a flexible connection element comprises a contact area at either end, each contact area comprising a conducting surface.

15. The detector support system according to claim 14, wherein at least one contact area at least partially surrounds a contact opening in the flexible foil. The detector support system according to any of the preceding claims, wherein a flexible connection element is provided with an auxiliary opening for fastening the flexible connection element, the shielding conductors extending from the auxiliary opening along the length of the flexible connection element in one direction only. The detector support system according to claim 16, wherein the signal conductor deviates from its longitudinal trajectory to pass around the auxiliary opening. A flexible electrical connection element for electrically connecting movable ion detectors in a mass spectrometer, the flexible electrical connection element comprising: an elongate electrically insulating flexible foil, a first contact area on a first end of the foil and a second contact area on a second end of the foil, each contact area comprising a conducting surface, a signal conductor extending over the foil to electrically connect the first contact area and the second contact area, a first shielding conductor and a second shielding conductor extending on either side of the signal conductor over at least part of its length in the same plane, spaced apart from the signal conductor, and a protective layer covering at least part of the signal conductor and the shielding conductors while leaving the contact areas exposed, wherein the signal conductor has a width of less than 0.5 mm, and wherein the flexible electrical connection element has a width which is at least 10 times its thickness. The flexible electrical connection element according to claim 18, wherein the spacing between the signal conductor and each shielding conductor is approximately equal to the width of the signal conductor. The flexible electrical connection element according to claim 18 or 19, wherein the spacing between the signal conductor and each shielding conductor is between 0.1 mm and 0.2 mm. The flexible electrical connection element according to any of claims 18 to 20, wherein the signal conductor has a width of between 0.1 mm and 0.2 mm.

22. The flexible electrical connection element according to any of claims 18 to 21, wherein the spacing between the signal conductor and each shielding conductor is between l/15^th and l/100^th of the width of the flexible electrical connection elements, preferably between l/25^th and l/50^th.

23. The flexible electrical connection element according to claims 18 to 22, which has a width at the part where the shielding conductors extend which is at least 25 times its thickness, preferably at least 50 times its thickness, more preferably at least 100 times its thickness.

24. The flexible electrical connection element according to claims 18 to 23, wherein the width of the flexible electrical connection element at the part where the shielding conductors extend is between 3 and 10 mm, and wherein the thickness of the flexible electrical connection element is between 0.1 mm and 0.5 mm.

25. The flexible electrical connection element according to claims 18 to 24, further comprising contact areas at both ends, each contact area comprising a conducting surface.

26. The flexible electrical connection element according to claim 25, wherein at least one of the first contact area and the second contact area at least partially surrounds a contact opening in the flexible foil.

27. The flexible electrical connection element according to any of claim 18 to 26, wherein the protective layer comprises a polyimide film, preferably Kapton™.

28. The flexible electrical connection element according to any of claims 18 to 27, wherein the protective layer leaves at least one area of each shielding conductor exposed, the at least one exposed area providing a further contact area.

29. The flexible electrical connection element according to any of claims 18 to 28, wherein an auxiliary opening is provided in the foil, the first shielding conductor and the second shielding conductor extending on one side of the auxiliary opening only.

30. The flexible electrical connection element according to claim 29, wherein the auxiliary opening is in the trajectory of the signal conductor, the signal conductor deviating from its trajectory around one side of the auxiliary opening.

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31. The flexible electrical connection element according to claim 30, wherein the signal conductor deviates from its trajectory towards the second shielding conductor, the first shielding conductor preferably extending further towards the auxiliary opening than the first shielding conductor.

32. The flexible electrical connection element according to any of claims 18 to 31, wherein at least one shielding conductor extends over at least 50% of the length of the signal conductor, preferably at least 60%.

33. The flexible electrical connection element according to any of claims 18 to 32, wherein the foil is made of an electrically insulating material and/or is provided with an electrically insulating layer.

34. A mass spectrometer comprising a detector support system according to claims 1 to 17 and/or at least one flexible electrical connection element according to any of claims 18 to 33.

35. The mass spectrometer according to claim 34, further comprising an ion source and/or a magnetic sector unit and/or an electrostatic sector unit.

36. The mass spectrometer according to claim 34 or 35, further comprising a Faraday cup mounted on a detector support.

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