Interface between ion trap and detection chamber of a charged aerosol detector

Abstract

The invention relates to an interface between an ion trap and a detection chamber of an electrical aerosol detector. The interface for guiding charged particles from an ion trap into a detection chamber comprises an electrically conductive tube configured to establish a connection for charged particles between the ion trap and the detection chamber, and an insulating member surrounding at least a portion of the tube and configured to establish an electrically insulating connection between the tube and the detection chamber. Furthermore, the invention relates to an assembly comprising an ion trap, a detection chamber and a corresponding interface, and to a corresponding method.

Description

Cross-references to related applications

[0001] This application is a continuation-in-part (CIP) of U.S. Patent Application No. 19 / 198,180, filed May 5, 2025. This application claims priority to U.S. Patent Application Nos. 19 / 198,180 and 19 / 198,229, filed May 5, 2025, and U.S. Patent Application No. 19 / 215,488, filed May 22, 2025. The entire contents of the foregoing applications are incorporated herein by reference. Technical Field

[0002] The present invention relates generally to an electrosol detector, and more particularly to an interface for delivering aerosols from an ion trap to a detection chamber. Background Technology

[0003] Charged aerosol detectors (CADs) are typically configured to generate a dry secondary aerosol of the analyte, which is then mixed with positively charged ions to generate a charged secondary aerosol via charge diffusion. To reliably measure the charged aerosol particles, excess ions are typically filtered out in an ion trap. The charged secondary aerosol is then guided into a detection chamber, where the ion current of the secondary aerosol can be measured in a Faraday cup.

[0004] Typically, during the process of guiding charged secondary aerosols from their charged region (e.g., mixing chamber) through an ion trap and into a detection chamber, it may be desirable to suppress (and ideally prevent) any charge loss on the aerosol particles while removing excess ions.

[0005] Charge loss on aerosol particles can occur primarily due to transport losses (caused by charge diffusion) and due to locally generated charges that cannot flow away (charge accumulation caused by triboelectricity). The triboelectric charge accumulation on surfaces in the gas flow can adversely provide an electric field, similar to an ion trap, that can deflect charged electrosols to the walls, making them unmeasurable. Therefore, these sources can be advantageously minimized.

[0006] Furthermore, while the use of a Faraday cup can be advantageously reliable and robust, and also allows for absolute measurement of time-constant ion currents, the Faraday cup is highly sensitive and should be well electrically insulated from its surrounding environment. This is typically achieved through a thick layer of insulating material, thus contradicting the desire to keep the flow path short to minimize diffusion losses.

[0007] Furthermore, Faraday cups can have relatively long time constants (typically around 0.1 s) due to their inherent capacitance and very high discharge resistance (10 GOhm) in the galvanometer. These typically result in poorer detection sensitivity (typically 2000 ions / s) and lower bandwidth compared to theoretically possible conditions, leading to long response times.

[0008] Therefore, due to the sensitivity and inertia of ion current measurements (and also due to the negative effects on charged particles), extra care may be needed to ensure the suppression and ideal prevention of localized charge buildup, i.e., good conductivity on all surfaces. Otherwise, charge buildup spontaneously flowing away via the Faraday cup or spontaneously transported away by the gas flow will adversely lead to signals irrelevant to the measurement. However, this may also require very good electrical insulation between the Faraday cup and the surrounding environment of the apparatus, including the inlet of the Faraday cup.

[0009] In the current design, the insulation of the Faraday cup relative to the ion trap is achieved using a feeder for guiding the aerosol into the Faraday cup, which is made of an insulating material. The insulating properties can be achieved by selecting a suitable material. Typically, plastic can be used for this purpose. However, in particular, when a gas stream carrying electrosol flows over the surface of a plastic material, the plastic can adversely cause the generation of charge through the triboelectric effect. The resulting charge accumulation can have several disadvantages as discussed above.

[0010] In this respect, PCTFE (polychlorotrifluoroethylene) exhibits the best insulating properties while also possessing suitable triboelectric properties (virtually no triboelectric charge induction on the surface). However, a certain thickness may be required to additionally provide the desired insulating properties. This may, to some extent, limit the possibility of keeping the aerosol transport path short to reduce the negative effects of charge diffusion over time. Conversely, tests using PEEK (polyetheretherketone) or PTFE (polytetrafluoroethylene) indicate that these materials may generally be unsuitable because they generate a high degree of charge on the surface due to gas flow.

[0011] The use of a guide belt electrosol via a plastic feeder may also have the following disadvantages: the feeder must be sealed to the outlet of the ion trap and may require a good fit with the outlet of the ion trap so that there are no edges in the flow path, which could otherwise impede gas flow.

[0012] In view of the foregoing, the object of the present invention is to overcome or at least mitigate the disadvantages and deficiencies of the prior art. More specifically, the object of the present invention is to provide an improved feed from the ion trap in the CAD to the detection chamber. Summary of the Invention

[0013] This invention achieves these objectives.

[0014] In a first aspect, the present invention relates to an interface for guiding charged particles from an ion trap into a detection chamber, the interface comprising: a conductive tube configured to establish a connection between the ion trap and the detection chamber for the charged particles; and an insulating member surrounding at least a portion of the tube and configured to establish an electrically insulating connection between the tube and the detection chamber.

[0015] In other words, the present invention relates to an interface between an ion trap and a detection chamber (e.g., within a CAD), wherein charged particles are guided only through a conductive tube and do not come into direct contact with the insulating material surrounding the tube. This advantageously allows for improved performance of such interfaces compared to existing technologies because charge buildup on the insulating material, such as due to triboelectricity, can be suppressed or even prevented. Furthermore, since the tube itself does not involve insulating the ion trap from the detection chamber, it can be shorter than tubes in current designs, allowing for reduced diffusion losses.

[0016] The tube can be configured to protrude partially into the testing chamber.

[0017] The tube can be made of metal. This is preferred because high conductivity is generally expected for tubes.

[0018] The tube is typically configured to guide gas and / or aerosol from the outlet of the ion trap to the detection chamber.

[0019] The tube provides a flow path from the tube inlet to the tube outlet. The flow path can be defined by the continuous, seamless inner wall of the tube.

[0020] The downstream end of the tube may extend beyond the downstream end of the insulating member. This, in turn, helps prevent any interaction between charged particles guided through the tube and the insulating member, and thus reduces the risk of charge buildup, for example, due to triboelectricity.

[0021] The tube can be configured to be fluidly connected to and electrically connected to the ion trap. Therefore, the tube can be configured to receive a gas flow and / or an electrosol from the ion trap while being at the same potential as the ion trap, which is preferably grounded.

[0022] The tube may include a length L ranging from 0.1 mm to 300 mm, preferably from 10 mm to 50 mm. T Additionally or alternatively, the tube includes an inner tube diameter D ranging from 1 mm to 50 mm, preferably from 2 mm to 10 mm. T .

[0023] The insulating member can be made of an electrically insulating material. In particular, the insulating member can be made of plastic. For example, the insulating member can be made of PTFE, PCTFE or PEEK, preferably PEEK or PTFE. Alternatively, the insulating member can be made of ceramic.

[0024] The insulating member can be configured to coaxially fix the tube to the test chamber (or vice versa). That is, the insulating member not only electrically insulates the test chamber from the tube, but also ensures the relative position of the tube and the test chamber by fixing them to each other, so that the relative position is maintained, thereby allowing the tube to extend coaxially relative to the test chamber.

[0025] The upstream portion of the insulating component can be connected to a pipe. This allows the insulating component to be fixed to the pipe relative to the test chamber, and the insulating component can also be connected to the test chamber.

[0026] The insulating member may preferably be hermetically connected to the pipe. The interface may include an O-ring for hermetically connecting the insulating member to the pipe. Alternatively, the insulating member may be hermetically glued or press-fitted to the pipe. In particular, the upstream portion of the insulating member may be hermetically connected to the pipe.

[0027] The interface may include an insulating gap between the downstream portion of the insulating member and the pipe. In other words, the downstream portion of the insulating member may surround the pipe such that the insulating gap is positioned between the downstream portion of the insulating member and the pipe.

[0028] The insulating gap may be filled with air. Therefore, the insulating gap can be an air gap. Alternatively, the insulating gap may be filled with a solid insulating material. For example, the insulating gap may be filled with adhesive, foam, or resin. Typically, the insulating gap is configured to insulate the downstream portion of the insulating member from the pipe. The distance between the downstream portion of the insulating member and the pipe can be in the range of 100 μm to 10 mm. It should be understood that this distance represents the width of the insulating gap between the downstream portion of the insulating member and the pipe.

[0029] In some embodiments, the insulating components and tubes may be made of composite materials. That is, they may be made of a composite material comprising a metal surface on one side and an insulating surface on the other. Such composite materials may be provided, for example, by two-component injection molding.

[0030] In another aspect, the present invention relates to a component comprising an ion trap, a detection chamber, and an interface according to the invention (e.g., as described above). A tube is fluidly connected to the ion trap. In particular, the tube inlet is fluidly connected to the ion trap outlet. Furthermore, the tube inlet is fluidly connected to the chamber outlet of the ion trap.

[0031] The tube can be electrically connected to the ion trap.

[0032] The tube can be permanently connected to the ion trap.

[0033] An ion trap may include a housing, wherein a tube may be integrally formed with the housing of the ion trap. That is, the housing and the tube of the ion trap may be formed from a single component. This advantageously ensures a good electrical connection between them and avoids any undesirable non-uniformities (e.g., edges or gaps) caused by imperfect fit between separate components.

[0034] The tube can extend into the testing chamber. Preferably, the downstream end of the tube can extend further into the testing chamber than the downstream end of the insulating member. In other words, the tube can extend further into the internal volume of the testing chamber than the insulating member.

[0035] The tube outlet can be located inside the testing chamber.

[0036] The tube can be coaxially installed into the testing chamber using insulating components.

[0037] The insulating gap can be fluidly connected to the test chamber. In particular, the insulating gap can be filled with the same air as the test chamber.

[0038] The testing chamber can be a Faraday cup.

[0039] An insulating member may be hermetically connected to the testing chamber. Alternatively or additionally, the insulating member may be included within the testing chamber. The insulating member may be permanently fixed to a portion of the testing chamber. For example, the insulating member, and at least a portion of the testing chamber, may be made of a composite material.

[0040] In another aspect, the present invention relates to an electrosol detector (CAD) comprising an atomizer, a spray chamber (including an impactor), a drying tube, a mixing chamber, a corona charger, an ion trap, a detection chamber, and an interface according to the invention, such as as described above. The CAD may include components comprising an ion trap, a detection chamber, and an interface, wherein such components are, for example, components according to the invention as described above.

[0041] In another aspect, the present invention relates to a method for guiding charged particles from an ion trap to a detection chamber within a charged sol detector (CAD), the method comprising guiding the charged particles from the ion trap into the detection chamber, wherein the charged particles are not guided along the surface of an insulating material. This advantageously allows for the suppression and ideally prevents triboelectric effects, which could otherwise lead to undesirable charge accumulation on the insulating material.

[0042] The steps of guiding charged particles from an ion trap into a detection chamber may include guiding the particles through a single continuous metal tube.

[0043] The step of guiding charged particles from an ion trap into a detection chamber includes guiding the particles through an interface according to the invention, for example as described above.

[0044] The ion trap and detection chamber can be included in the components according to the invention, for example as described above.

[0045] The method may also include applying an electric field within the ion trap, which is configured to remove highly mobile charged particles.

[0046] The method may also include detecting the charge of charged particles supplied to the detection chamber.

[0047] Below, we will refer to the interface implementation schemes. These implementation schemes are abbreviated as the letter "I" followed by a number. Whenever "interface implementation scheme" is mentioned in this document, it refers to these implementation schemes. 11. An interface for guiding charged particles from an ion trap into a detection chamber, the interface comprising: A conductive tube, configured to establish a connection between the ion trap and the detection chamber for the charged particle; and An insulating member surrounds at least a portion of the tube and is configured to establish an electrically insulating connection between the tube and the detection chamber. I2. The interface according to the previous interface implementation scheme, wherein the tube is configured to partially protrude into the detection chamber. I3. The interface according to any one of the foregoing interface implementation schemes, wherein the tube is made of metal. I4. The interface according to any one of the foregoing interface embodiments, wherein the tube is configured to guide gas and / or aerosol from the outlet of the ion trap to the detection chamber. I5. The interface according to any one of the foregoing interface implementation schemes, wherein the pipe provides a flow path from the pipe inlet to the pipe outlet. I6. The interface according to the previous interface implementation scheme, wherein the flow path is defined by the continuous seamless inner wall of the tube. I7. The interface according to any one of the foregoing interface embodiments, wherein the downstream end of the tube extends beyond the downstream end of the insulating member. I8. The interface according to any one of the foregoing interface embodiments, wherein the tube is configured to be fluidly connected to the ion trap and electrically connected to the ion trap. I9. The interface according to any one of the foregoing interface embodiments, wherein the tube includes a tube length L in the range of 0.1 mm to 300 mm, preferably in the range of 10 mm to 50 mm. T . I10. The interface according to any one of the foregoing interface embodiments, wherein the tube includes an inner tube diameter D in the range of 1 mm to 50 mm, preferably in the range of 2 mm to 10 mm. T . I11. An interface according to any one of the foregoing interface implementation schemes, wherein the insulating member is made of an electrically insulating material. I12. The interface according to any one of the foregoing interface embodiments, wherein the insulating member is made of plastic. I13. The interface according to any one of the foregoing interface embodiments, wherein the insulating member is made of PTFE, PCTFE or PEEK, preferably PEEK or PTFE. I14. An interface according to any one of the interface implementation schemes I1 to I12, wherein the insulating member is made of ceramic. I15. An interface according to any one of the foregoing interface embodiments, wherein the insulating member is configured to coaxially fix the tube to the detection chamber (or vice versa). I16. The interface according to any one of the foregoing interface embodiments, wherein the upstream portion of the insulating member is adjacent to the pipe. I17. The interface according to any one of the foregoing interface embodiments, wherein the insulating member is hermetically connected to the pipe. I18. The interface according to the preceding interface embodiment, wherein the interface includes an O-ring for hermetically connecting the insulating member to the tube. I19. The interface according to the penultimate interface implementation, wherein the insulating member is sealed and glued or press-fitted to the tube. I20. An interface according to any one of the three interface embodiments described above, wherein the upstream portion of the insulating member is hermetically connected to the pipe. I21. The interface according to any one of the foregoing interface embodiments, wherein the interface includes an insulating gap between the downstream portion of the insulating member and the tube.

[0048] In other words, the downstream portion of the insulating member can surround the tube, such that an insulating gap is provided between the downstream portion of the insulating member and the tube. I22. The interface according to the previous interface implementation scheme, wherein the insulating gap is filled with air. I23. The interface according to the penultimate interface implementation scheme, wherein the insulating gap is filled with solid insulating material. I24. The interface according to the preceding interface implementation scheme, wherein the insulating gap is filled with adhesive, foam or resin. I25. An interface according to any one of the four interface embodiments described above, wherein the insulating gap is configured to insulate the downstream portion of the insulating member from the tube. I26. The interface according to any one of the five interface embodiments described above, wherein the distance between the downstream portion of the insulating member and the tube is in the range of 100 μm to 10 mm. I27. The interface according to any one of the foregoing interface embodiments, wherein the insulating member and the tube are made of composite material.

[0049] In other words, they can be made of a composite material that includes a metal surface on one side and an insulating surface on the other side. I28. An interface according to any of the foregoing interface implementation schemes other than I27, wherein the insulating member is installed to the tube by press fitting or adhesive bonding.

[0050] The following section will refer to component implementation schemes. These schemes are abbreviated as the letter "A" followed by a number. Whenever "component implementation scheme" is mentioned in this document, it refers to these schemes. A1. A component comprising an ion trap, a detection chamber, and an interface according to any one of the foregoing interface embodiments. A2. The component according to the preceding component embodiment, wherein the tube is fluidly connected to the ion trap. A3. The component according to any one of the foregoing component embodiments, wherein the interface includes the features of I5, and wherein the tube inlet is fluidly connected to the ion trap outlet. A4. The component according to any one of the foregoing component embodiments, wherein the interface includes the feature of I5, and wherein the tube inlet is fluidly connected to the chamber outlet of the ion trap. A5. The component according to any one of the foregoing component embodiments, wherein the tube is electrically connected to the ion trap. A6. The component according to any one of the foregoing component embodiments, wherein the tube is permanently connected to the ion trap. A7. The component according to any one of the foregoing component embodiments, wherein the ion trap includes a housing, and wherein the tube is integrally formed with the housing of the ion trap. A8. The component according to any one of the aforementioned component embodiments, wherein the tube extends into the detection chamber. A9. The component according to any one of the aforementioned component embodiments, wherein the downstream end of the tube extends further into the detection chamber than the downstream end of the insulating member.

[0051] In other words, the tube can extend further into the internal volume of the testing chamber than the insulating component. A10. The component according to any one of the foregoing component embodiments, wherein the interface includes the feature of I5, and wherein the tube outlet is located in the detection chamber. A11. The component according to any one of the aforementioned component embodiments, wherein the tube is coaxially mounted to the test chamber via the insulating member. A12. The component according to any one of the foregoing component embodiments, wherein the interface includes the feature of I21, and wherein the insulating gap is fluidly connected to the detection chamber. A13. The component according to any one of the foregoing component embodiments, wherein the interface includes the feature of I21, and wherein the insulating gap is filled with the same air as the detection chamber. A14. The component according to any one of the aforementioned component implementation schemes, wherein the testing chamber is a Faraday cup. A15. The component according to any one of the foregoing component embodiments, wherein the insulating member is included in the testing chamber. A16. The component according to any one of the foregoing component embodiments, wherein the insulating member is hermetically connected to the detection chamber. A17. The component according to any one of the foregoing component embodiments, wherein the insulating member and at least a portion of the detection chamber are made of a composite material. A18. The component according to any one of the foregoing component embodiments, wherein the insulating member is permanently fixed to a portion of the testing chamber.

[0052] The following sections will refer to the CAD implementation schemes. These implementation schemes are abbreviated as the letter "C" followed by a number. Whenever "CAD implementation scheme" is mentioned in this document, it refers to these implementation schemes. C1. An electrosol detector (CAD) comprising an atomizer, a spray chamber (including an impactor), a drying tube, a mixing chamber, a corona charger, an ion trap, a detection chamber, and an interface according to any one of the foregoing interface embodiments. C2. An electrosol detector according to the preceding CAD embodiment, wherein the CAD includes a component comprising the ion trap, the detection chamber, and the interface, wherein the component is the component according to any one of the preceding component embodiments.

[0053] The following describes the implementation methods. These implementation methods are abbreviated as the letter "M" followed by a number. Whenever this document refers to "implementation methods," it refers to these implementation methods. M1. A method for guiding charged particles from an ion trap to a detection chamber within a charged electrosol detector (CAD), the method comprising: The charged particles are guided from the ion trap into the detection chamber. The charged particle is not guided along the surface of the insulating material. M2. The method according to the preceding method embodiment, wherein the step of guiding charged particles from the ion trap into the detection chamber includes guiding the particles through a single continuous metal tube. M3. The method according to any one of the foregoing method embodiments, wherein the step of guiding a charged particle from the ion trap into the detection chamber includes guiding the particle through an interface according to any one of the foregoing interface embodiments. M4. The method according to any one of the foregoing method embodiments, wherein the ion trap and the detection chamber are included in the component according to any one of the foregoing component embodiments. M5. The method according to any one of the foregoing method embodiments, wherein the method further includes applying an electric field within the ion trap, the electric field being configured to remove highly mobile charged particles. M6. The method according to any one of the foregoing embodiments, wherein the method further includes detecting the charge of the charged particle provided to the detection chamber. Attached Figure Description

[0054] Embodiments of the invention will now be described with reference to the accompanying drawings. These embodiments are to be described by way of example only and do not limit the invention. Figure 1 A flowchart for electrosol detection is described; Figure 2 The existing ion trap, feed element, and detection chamber are described; Figure 3 An embodiment of a component according to the invention is described, the component including an ion trap, an interface, and a detection chamber; Figure 4A and Figure 4B The high charge transport mobility of the component according to the invention is illustrated compared to prior art components; and Figure 5A and Figure 5B Another comparative measurement between known components and embodiments according to the invention is illustrated.

[0055] It should be noted that not all figures are accompanied by all reference numerals. Instead, some reference numerals have been omitted in some figures for the sake of brevity. Embodiments of the invention will now be described with reference to the accompanying drawings. Detailed Implementation

[0056] Very commonly, charged electrosol detectors (CADs) are used to measure the charge of an analyte aerosol, which may include particles with diameters ranging from 10 nm to 100 μm. Several steps are typically performed in the CAD before aerosol detection.

[0057] Although the principles of CAD are well known in the field, reference Figure 1 Here is a brief discussion of a typical workflow in CAD. First, a primary aerosol 110 of the analyte is generated in a spray chamber by atomization (e.g., pneumatic atomization) using a primary gas stream 105. Second, as the primary aerosol is guided through the spray chamber, an impactor can be used to remove large droplets to generate a secondary aerosol 115. Subsequently, the secondary aerosol can be dried 120, for example, by guiding it through a heated evaporation tube.

[0058] A secondary gas stream 140 can be provided, and the secondary gas can be positively charged via corona discharge 145. The positively charged secondary gas (e.g., nitrogen ions) and dry secondary aerosol can then be mixed in a mixing chamber to charge the secondary aerosol through the positively charged secondary gas 160. Subsequently, an ion trap, typically used, can be used to remove excess charge from the secondary gas 165. Finally, the charge on the secondary aerosol can be detected, for example, in a Faraday cup in a detection chamber 170.

[0059] refer to Figure 2 A cross-sectional view of an assembly including an ion trap 210 and a downstream detection chamber 220, as currently known in the art, is briefly discussed. Similarly, once the secondary aerosol has been charged 145, the charge applied by diffusion can be measured in the detection chamber 220. For this reason, excess positive charge can be advantageously filtered out in the ion trap 210. This filtering can be implemented by inertia.

[0060] Rod 212 can be concentrically placed in the flow path through ion trap 210, and a positive potential can be applied to rod 212. This results in an electric field being generated between rod 212 and the housing 214 of the ion trap, which defines the flow path and is typically electrically grounded. Therefore, the positive potential on the rod generates an electric field in the flow path. Typically, the ratio of electric field strength to velocity in the flow path determines which charge / mass ratio is being filtered. Positively charged ions (e.g., nitrogen ions) have high mobility due to their low mass compared to positively charged secondary aerosol particles. Therefore, they can be pressed against the outer wall of the flow path provided by housing 214, and their charge can be dissipated via the grounding of housing 214. The low mobility of secondary aerosol particles allows them to flow through ideally unimpeded.

[0061] Once the charged secondary aerosol has passed through the ion trap 210, it can be fed into the detection chamber 220 via the corresponding feeder 230. In the detection chamber 220, the charge of the secondary aerosol can be measured, for example, using a Faraday cup. The measured ion current is typically in the range of 30 fA to 1 nA.

[0062] like Figure 2As can be seen, the current design relies on an insulating feeder 230 that guides the aerosol into the Faraday cup and simultaneously provides the required insulation of the Faraday cup relative to the ion trap. A first portion 230-I of the feeder may be conductive and extends into the ion trap 210, and this first portion may be electrically connected to the ion trap such that it is at the same potential. A second portion 230-II may be insulating to provide electrical insulation between the ion trap 210 and the detection chamber 220. That is, in the current design, the interface 230 (or feeder) between the ion trap 210 and the detection chamber 220 may include two portions 230-I, 230-II, each providing a portion of the flow path. This may be disadvantageous, for example, due to the discontinuous inner surface traversed by which the gas and / or aerosol is guided from the chamber of the ion trap to the detection chamber.

[0063] Furthermore, as already discussed, such known solutions can have additional disadvantages: First, they typically require a certain length to ensure good electrical insulation, and thus limit the extent to which the total flow path between the ion trap and the Faraday cup can be kept short (to reduce diffusion losses). Second, since a portion of the flow path can be provided by the surface of the insulating material, the insulating material can easily accumulate charge due to triboelectricity. However, it is preferable to prevent localized charge accumulation in the ion trap and in the feed, as it can be disadvantageous for several reasons: on the one hand, accumulated charge may lead to erroneous measurement signals due to spontaneous dissipation via the Faraday cup and / or spontaneous transport of accumulated charge via the gas flow. On the other hand, within the feed, it can also act similarly to an ion trap on charged sols, since the accumulated charge provides an electric field that can deflect the charged sols toward the inner wall of the feed, making them unmeasurable.

[0064] Finally, the feed element is further sealed to the outlet of the ion trap and may require a good fit with the outlet of the ion trap so that there are no edges in the flow path that could otherwise impede the gas flow.

[0065] To mitigate these drawbacks and disadvantages, the present invention generally provides an interface for guiding aerosols from an ion trap to a detection chamber (e.g., a Faraday cup), the interface comprising a metal tube and an insulating member surrounding at least a portion of the metal tube. The insulating member can be configured to allow an electrically insulating connection between the tube and the detection chamber (e.g., a Faraday cup).

[0066] refer to Figure 3Exemplary embodiments of the interface 330 according to the foregoing invention are discussed. The interface 330 may include a conductive tube 332 (preferably a metal tube 332) configured to guide a gas and / or aerosol stream from the outlet of the ion trap 310 to the detection chamber 320. The tube 332 may be electrically insulated from the detection chamber 320 by an insulating member 334 surrounding at least a portion of the tube 332. The insulating member 334 may establish a mechanical connection between the tube 332 and the detection chamber 320, wherein the connection is electrically insulated.

[0067] The tube 332 may protrude into the detection chamber 320. Specifically, the downstream end of the tube 332 may protrude further into the detection chamber 320 than the downstream end of the insulating member 334. In other words, the tube 332 may extend further into the internal volume of the detection chamber 320 than the insulating member 334.

[0068] Additionally, interface 330 may include an insulating gap 336 between the downstream portion of insulating member 334 and tube 332. The insulating gap 336 may be, for example, an air gap, i.e., it may be filled with air. Typically, the insulating gap 336 improves the insulation properties between the interface and the detection chamber 320. It should be understood that the insulating gap 336 may include different geometries. It may be, for example, larger than depicted in the exemplary embodiments and / or include different shapes. Specifically, the geometry of the insulating gap 336 may depend on the geometry of insulating member 334. The distance between the downstream portion of insulating member 334 and tube 332 (which may constitute the insulating gap 336) may be in the range of 100 μm to 10 mm.

[0069] In some embodiments, the insulating gap may be filled with an insulating material. For example, insulating gap 336 may be filled with an adhesive (e.g., a two-component adhesive), foam, or resin. Any liquid material that can be hardened and is non-conductive after hardening is feasible.

[0070] The insulating member 334 may be made of an electrically insulating material, such as plastic. For example, the insulating member 334 may be made of PTFE or PEEK. Alternatively, the insulating member may be made of ceramic. The insulating member 334 may be included in the testing chamber 320.

[0071] During operation, slight overpressure may exist in the testing chamber, for example, up to 300 mbar above ambient pressure. Therefore, the interface may include a seal 328 (e.g., an O-ring) between the tube 332 and the insulating member 334 to provide a sufficiently tight connection between them. Alternatively, the insulating member may be glued or press-fitted to the tube.

[0072] The tube 332 is typically connected to the ion trap 310. Preferably, the tube is not only mechanically connected to the ion trap 310, but also electrically connected to it. In some embodiments, the tube 332 may be permanently connected to the housing 314 of the ion trap. Specifically, the tube 332 may be integrally formed with the housing 314 of the ion trap. This advantageously allows for a good electrical connection and prevents any obstruction in the flow path due to imperfect alignment between the ion trap 310 and the interface 330.

[0073] Preferably, the upstream end of tube 332 may extend to the chamber of the ion trap, such that tube 332 may receive aerosols at the outlet of the chamber of the ion trap 332 and guide them to the detection chamber 320.

[0074] The tube may include a length L ranging from 0.1 mm to 300 mm, preferably from 10 mm to 50 mm. T Additionally, the inner tube diameter D of tube 332 may be in the range of 1 mm to 50 mm, preferably in the range of 2 mm to 10 mm. T .

[0075] In some implementations, composite materials may be used, particularly insulating and metallic composite materials. Specifically, this allows for the provision of materials having a metallic surface on one side and an insulating surface on the other. This may, for example, allow insulating components and tubes to be made of composite materials, and / or insulating components as well as a portion of the detection chamber (e.g., the equipotential metal of a Faraday cup) to be made of composite materials. Such composite materials may, for example, be manufactured using two-component injection molding.

[0076] Therefore, in some embodiments, the insulating member 334 may be integrated into the test chamber 320 (e.g., a Faraday cup). That is, the insulating member may be permanently fixed to a portion of the test chamber 320, for example, by adhesive bonding or two-component injection molding.

[0077] In other words, the present invention provides an interface comprising a continuous metal tube for feeding aerosols from an ion trap to a detection chamber. Compared to plastics, metals offer optimal electrical properties for dissipating potentially generated surface charges. The metal tube can extend into the Faraday cup via a corresponding insulating element. Therefore, the insulating material no longer interacts directly with the gas / aerosol flow from the ion trap to the Faraday cup. Thus, the choice of insulating material can be decoupled from its triboelectric properties. This advantageously allows the use of plastics with very good electrical insulation properties, such as PTFE or PEEK.

[0078] Furthermore, the continuous channel provided by the metal tube advantageously eliminates the need for any seals within the channel (as required in the prior art), where the insulating feeder requires a sealed connection to the ion trap. Similarly, precise fitting of connecting parts is not required to avoid adverse effects on gas flows containing aerosols. Instead, it provides a flow path with a smooth, continuous surface. In addition to improved flow characteristics, shorter delivery paths can be achieved through design.

[0079] In addition, the insulation gap provides additional insulation between the metal tube and the testing chamber.

[0080] The Faraday cup perfectly preserves its metallic surface and is therefore able to dissipate the charge of the aerosol to the galvanometer.

[0081] Therefore, in general, aerosols can be continuously fed from the ion trap using a metal tube. Due to the excellent electrical properties of metal, the charge potentially generated by friction (triboelectricity) can be optimally dissipated. The electrical insulation of the detection chamber (e.g., a Faraday cup) can be molded around the tube. Insulation gaps (e.g., air gaps) also ensure that surface charges cannot flow onto the insulating members of the Faraday cup; that is, they prevent charge flow. Furthermore, at the point of contact between the insulating member 334 and the tube 332, the potential charge on the insulating member 334 can be dissipated via the conductive tube 332 due to good conductivity and grounding connection. Moreover, since the downstream end of the tube 332 protrudes further into the detection chamber than the downstream end of the insulating member 334, the potential charge on the insulating member does not affect the charged aerosol particles guided into the detection chamber. The downstream end of the tube can extend, for example, beyond the downstream end of the insulating member by 0.01 mm to 300 mm, preferably 0.1 mm to 45 mm.

[0082] about Figure 4A , Figure 4B , Figure 5A and Figure 5B Exemplary measurements are discussed, demonstrating the improvements achieved using the present invention compared to prior art designs. It should be noted that, in addition to the present invention, the design of the ion trap is further improved by introducing a separation portion 372 and a trap insulation gap 374 to avoid charge accumulation on the trap insulation member 376. Further details regarding this novel ion trap design can be found in U.S. Patent Application 19 / 198,229, filed May 5, 2025, entitled "Ion trap for charged aerosol detector," the entire contents of which are incorporated herein by reference.

[0083] Figure 4AThe diagram illustrates the current measured due to positively charged nitrogen ions in a Faraday cup, wherein the Faraday cup is fluidly connected to an upstream ion trap via an assembly including a feed element according to the prior art (see [link]). Figure 2 ). Figure 4B The same measurement is illustrated using components including the interface according to the invention and an improved ion trap design. For both measurements, the ion trap is shut off to provide a high flux of positively charged nitrogen atoms.

[0084] As can be seen, this invention allows for current levels approximately four times higher than those achieved using existing feeders / interfaces. This highlights the improved transport of charged particles due to this invention and the improved ion trap design.

[0085] Similarly, Figure 5A Measurements were depicted using components from existing technologies, while Figure 5B Measurements performed using components including the interface according to the invention and an improved ion trap design are described.

[0086] refer to Figure 5A The thermal noise of the galvanometer was measured from 0 to 1 minute. Subsequently, from 1 to 2 minutes, the aerosol particles in the mixing chamber that were not charged by positive nitrogen ions were measured. Here, the natural charge of the aerosol particles originating from the water eluent of the HPLC can be seen. However, this is generally expected to be almost neutral, similar to the measurement between 0 and 1 minutes. From 2 to 3 minutes, positively charged nitrogen ions were introduced, and the ion trap was turned off. Expectedly, the signal increased when excess positive nitrogen ions were measured along with the aerosol particles from the water eluent. From 3 to 4 minutes, the ion trap was turned on, and the aerosol particles from the water eluent were charged by positive nitrogen ions in the mixing chamber. This indicates a normal state in the detector.

[0087] refer to Figure 5B This illustrates the same measurement using the interface according to the invention. It should be noted that, with... Figure 5A In comparison, the y-axis, which indicates current in pA, is scaled by 10. -6 The aerosol from the water eluent was nearly neutral within 1 to 2 minutes, comparable to the state when no aerosol entered the detector (0 to 1 minute). Furthermore, the signal was significantly reduced during normal measurements (3 to 4 minutes). This is generally attributed to the smaller effect of charge accumulation on insulating materials, for example, due to triboelectricity. Overall, these comparative measurements indicate that the aerosol particles being analyzed are uncharged or unaffected by the flow through the device, i.e., indicating a reduction in triboelectricity, and that background noise is reduced because the charge enters the detection chamber more continuously.

[0088] Whenever relative terms such as “about,” “substantially,” or “approximately” are used in this specification, such terms should also be interpreted as including precise terms. That is, for example, “substantially straight” should be interpreted as including “(perfectly) straight.”

[0089] Whenever steps are described above or otherwise in the appended claims, it should be noted that the order in which steps are listed herein may be accidental. That is, unless otherwise stated or unless it is clear to a person skilled in the art, the order in which steps are described may be accidental. That is, when this document states, for example, that a method includes steps (A) and (B), this does not necessarily mean that step (A) precedes step (B), but it is also possible that step (A) is performed (at least partially) concurrently with step (B), or that step (B) precedes step (A). Furthermore, when step (X) is considered to precede another step (Z), this does not mean that there are no steps between steps (X) and (Z). That is, step (X) preceding step (Z) covers the case where step (X) is performed directly before step (Z), but also covers the case where one or more steps (Y1) are performed after step (X) is performed... and then step (Z) is performed. When terms such as "after" or "before" are used, corresponding factors also need to be considered.

[0090] Although preferred embodiments have been described above with reference to the accompanying drawings, those skilled in the art should understand that these embodiments are provided for illustrative purposes only and should not in any way be construed as limiting the scope of the invention, which is defined by the claims.

Claims

1. An interface for guiding charged particles from an ion trap into a detection chamber, the interface comprising: A conductive tube configured to establish a connection between the ion trap and the detection chamber for the charged particles; and An insulating member surrounds at least a portion of the conductive tube and is configured to establish an electrically insulating connection between the conductive tube and the detection chamber.

2. The interface according to claim 1, in, The conductive tube provides a flow path from the tube inlet to the tube outlet; and The flow path is defined by the continuous, seamless inner wall of the conductive tube.

3. The interface according to claim 1 or 2, wherein, The insulating component is connected to the conductive tube in a sealed manner.

4. The interface according to claim 1 or 2, wherein, The downstream end of the conductive tube extends beyond the downstream end of the insulating member.

5. The interface according to claim 1 or 2, wherein, The conductive tube is configured to be fluidly connected to the ion trap and electrically connected to the ion trap.

6. The interface according to claim 1 or 2, wherein, The interface includes an insulating gap between the downstream portion of the insulating member and the conductive tube.

7. A component comprising an ion trap, a detection chamber, and an interface, the interface comprising: A conductive tube configured to establish a connection for charged particles between the ion trap and the detection chamber; and An insulating member surrounds at least a portion of the conductive tube and is configured to establish an electrically insulating connection between the conductive tube and the detection chamber.

8. The component according to claim 7, wherein, The conductive tube is fluidly connected to the ion trap and electrically connected to the ion trap.

9. The component according to claim 7 or 8, wherein, The ion trap includes a housing, wherein the conductive tube is integrally formed with the housing of the ion trap.

10. The component according to claim 7 or 8, wherein, The downstream end of the conductive tube extends further into the detection chamber than the downstream end of the insulating member.

11. The component according to claim 7 or 8, wherein, The testing chamber is a Faraday cup.

12. The component according to claim 7 or 8, wherein, The insulating component is sealed to the testing chamber.

13. A method for guiding charged particles from an ion trap to a detection chamber within an electrosporation detector (CAD), the method comprising: The charged particles are guided from the ion trap into the detection chamber. The charged particles are not guided along the surface of the insulating material.

14. The method according to claim 13, wherein, The step of guiding the charged particles from the ion trap into the detection chamber includes guiding the charged particles through a single continuous metal tube.

15. The method according to claim 13, wherein, The method further includes detecting the charge of the charged particles supplied to the detection chamber.

16. The method according to any one of claims 13 to 15, wherein, The step of guiding the charged particles from the ion trap into the detection chamber includes guiding the charged particles through an interface, the interface comprising: A conductive tube, configured to establish a connection between the ion trap and the detection chamber for the charged particles; and An insulating member surrounds at least a portion of the conductive tube and is configured to establish an electrically insulating connection between the conductive tube and the detection chamber.

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