Electrostatic ion trap configuration

Abstract

An electrostatic ion trap or array of electrostatic ion traps having a longitudinal length of no more than 10 mm and / or at least one electrode with a ground capacitance of no more than 1 pF is provided. A first set of planar electrodes and a second set of planar electrodes can be distributed along a longitudinal axis, at least some of the first set of planar electrodes and the second set of planar electrodes being configured to receive an electrostatic potential, and a second set of planar electrodes for confining ions received in a space between the first set of planar electrodes and the second set of planar electrodes. The array can include an inlet for receiving an ion beam, the inlet configured such that a portion of the ion beam can be trapped in each of the ion traps. Signals indicative of ion mass and charge data can be obtained from a plurality of electrostatic ion traps in the array. The mass and charge data can be combined for identifying a composition of a mixture of different analyte ions.

Description

Technical Field

[0001] The present disclosure relates to electrostatic ion traps, arrays of electrostatic ion traps, and methods of analyzing ion beams.

[0002] CROSS-REFERENCE TO RELATED APPLICATIONS

[0003] This application claims priority to U.S. patent application No. 17 / 823,618, filed on August 31, 2022, which is incorporated herein by reference. Background Art

[0004] High-resolution accurate mass (HR / AM) analyzers using electrostatic fields are well known. These analyzers include: multi-reflection time-of-flight (mrTOF) analyzers using destructive ion detection (e.g., using secondary electron multipliers), including those described in WO2013110587, WO2019202338, WO2017087470, and references therein; track-trapping mass analyzers, including those described in US5886346, US7767960, US7985950; and electrostatic ion traps with closed and open trajectories, including those described in US5880466, US9728384, US10453668, and DZ Keifer et al. Analyst Vol. 142, p. 1654 (2017).

[0005] Track trap mass analyzers and some other electrostatic ion traps use image currents for non-destructive detection of ions. Using sufficiently low capacitance of the detection electrodes and transistors of the preamplifier, individual ions can be detected over an extended detection duration. This is practiced in, for example, charge detection mass spectrometry (CDMS), as described in US11232941, US11227759, US2022068624. Recently, ARTodd et al. J.Am.Soc.Mass Spectrom 2020, Vol. 31, pp. 146-154 demonstrated the detection of a single elementary charge.

[0006] The throughput of existing HR / AM analyzers is limited to tens to hundreds of spectra per second. For efficiency reasons, as many species as possible are therefore gathered in a single MS or MS / MS spectrum, up to the limit of space charge. Space charge effects may ultimately limit the dynamic range and depth of analysis.

[0007] Thus, such analyzers can identify no more than 10 to 100 of the most abundant species per second. Although this level has increased dramatically in the past few years due to the widespread adoption of fast liquid chromatography and data-independent acquisition (DIA), new approaches are needed to achieve the next leap in productivity, especially in proteomics.

[0008] Recent breakthroughs in the informatics foundation of DIA, including the adoption of machine learning, have significantly improved the reliability of deconvoluting mixed spectra into separate fragment spectra. This approach can be reliably used for the most intense components of mixed spectra, but cannot be applied to species at the lower end of the dynamic range, since these species are represented by only a few ions. This ultimately limits the depth of analysis, particularly in proteomics, where the dynamic range of concentrations can span 10 to 12 orders of magnitude. The problem is even more acute in single-cell proteomics, where the total number of peptides available for analysis is limited to billions per cell, with only hundreds of millions of ions actually entering the mass spectrometer.

[0009] Different techniques for enrichment have been tried on the sample preparation side (Seer, classification) or the ion sorting side (e.g., as shown in US9812310, US10199208). These techniques usually work by producing many fractions, which then need to be analyzed individually or in a pool. Performance seems to have been improved by these methods, but not equally well for all species, leaving many low-abundance species unrepresented or even lost in the process. At the same time, the individual analysis of fractions in the same mass analyzer proportionally reduces the throughput, because the mass analyzer is essentially a single-channel device.

[0010] The array of mass analyzer has been considered to solve this throughput problem. The array of electrostatic ion trap has been extensively studied, including for example US5206506, US7718959, US2003089846, US6762406, WO2006049623, US9779930, WO2021061650 and US7985950 (in the form of orbital trap mass analyzer). The array of some other analyzers has also been considered, such as US7985950, US10049867, US10593533, US2008067349. All these arrays transmit ions in three dimensions so that the overall multi-analyzer mass spectrometer space is efficient. Nevertheless, due to the inherent limitation of electrode precision, it is difficult to prove high resolution, accurate mass capability in such arrays.

[0011] Improvements in arrays of electrostatic ion traps and mass analyzers are desired to address these challenges. Summary of the invention

[0012] In this context, an electrostatic ion trap according to claim 1, an array of electrostatic ion traps according to claim 26, and a method of analyzing an ion beam containing a mixture of different analyte ions according to claim 32 are provided. Preferred and / or optional features are disclosed in the dependent claims.

[0013] A new type of microscale electrostatic ion trap (μEST) is proposed, the typical length of the trap does not exceed 10mm and optionally does not exceed 5mm, 2mm, 1mm or 0.5mm. Additionally or alternatively, at least one of the electrodes (specifically, the detection electrode) has a capacitance to ground of no more than 1pF. The μEST advantageously has planar electrodes distributed along the longitudinal axis (z dimension). Each electrode extends perpendicular to the longitudinal axis (in width or x dimension). A set of electrodes distributed along the longitudinal axis is spaced apart from a second electrode set (also parallel to the longitudinal axis) to define a trapping region between the electrode sets (and to define a height or y dimension). An electrostatic potential is applied to at least some of the electrodes for limiting ions received in the trapping region. In order to improve the field, the two electrode sets may mirror each other in their configuration. Implementing trap electrodes on a submillimeter scale (preferably with nanometer tolerances) allows high resolution. The μEST may have a controller to configure the operation of the μEST, or a group of μESTs may share a controller. The controller may include a processor and a computer program configured to operate on the processor.

[0014] Due to its small size and the use of electrostatic potential for ion trapping, μEST allows confinement of a small number of ions in a small space, typically no more than 100, 50, 30, 20, 10, 5 or even a single charged particle. However, high resolution accurate mass analysis is possible. Thus, new types of ion analysis become possible. Measurement times of no more than 20 ms and / or acceleration voltages of no more than 200 V and / or no more than 10 ions in the electrostatic ion trap can be achieved. -7 mbar gas pressure. Furthermore, μEST can be efficiently and cost-effectively manufactured, for example, using photolithography techniques. μEST can be formed as part of an integrated circuit. Modern micro- and nano-lithography techniques can allow nanometer tolerances to be achieved on planar wafers.

[0015] One or more of the electrodes (typically along the longitudinal axis toward the center of the trap) are used for ion detection by inducing an image current. Reliable image current detection of a single elementary charge is achieved by the microscale design of the trap. As described above, the capacitance of one, some or each detection electrode to ground is kept low, typically not exceeding (or less than) 1pF, 500fF, 100fF, 50fF, 10fF, 5fF or 1fF. Such low capacitance allows single charge detection. A transistor (e.g., FET or JFET) can be connected to one or more detection electrodes, which can also be formed photolithographically.

[0016] By applying a suitable potential, some of the electrodes (usually the outer electrodes) can be used for reflection of ions. Other electrodes, usually between the reflection electrode and the detection electrode, can receive a suitable potential for accelerating the ions. By reducing the potential on the reflection electrode, the ions can be allowed to enter the trap. Then, the potential on the reflection electrode can be raised to limit the ions to the trapping area. The gap between adjacent electrodes in the longitudinal (or z) dimension is usually no more than 100 μm, preferably no more than 50 μm and usually much smaller, for example no more than (or less than) 20 μm, 10 μm or 5 μm. The spacing (e.g., free space) between electrodes on different planes (in height or y dimension) is usually no more than or less than 100 μm, and usually no more than or less than 80 μm or 70 μm.

[0017] Each set of electrodes may be formed on a corresponding planar substrate (e.g., a wafer). To form a μEST, two substrates may be positioned so that the electrodes are opposite each other. A spacer (or multiple spacers) may separate the electrode sets (or substrates or wafers). One or more spacers may include conductive spacers for electrical coupling of the electrodes.

[0018] In some embodiments, the arrangement of each set of electrodes is substantially symmetrical between opposite sides of the center of the electrostatic trap along the longitudinal axis (z=0 line). Additionally or alternatively, at least some of the electrodes have an arcuate shape at one or both edges on the longitudinal axis. For example, some of the electrodes may have a curved shape, an arcuate shape, a circular shape, or an elliptical shape. When planar electrodes are used, the curved shape permits improved ion accommodation.

[0019] The wavy, modulated or multi-bend shape of the border between adjacent electrodes can be further advantageous. Since the electrostatic potential in the trap is the convolution (or blur) of the potential on the border, such a shape of the electrode interface can provide a greater degree of control over the electrostatic capture field. According to this principle, strip electrodes can be used. For example, the duty cycle of the strip electrodes can be changed along the longitudinal axis of the ion trap. Such strip electrodes (especially when maintained at different potentials) can define one or more lenses. Using such modulated (wavy or multi-bend) borders (especially for strip electrodes) in this way can reduce the number of different non-zero potentials applied to separate electrodes in order to generate capture or confinement sites. For example, two different non-zero potentials can be easily used, and by further optimization, this can be reduced to a single non-zero electrostatic potential.

[0020] Fragmentation of ions within the μEST is possible. For example, this can be achieved by emitting pulses from a UV or IR laser at the trapping region. The laser can emit pulses in a direction orthogonal to the longitudinal axis (i.e., along the width dimension of the trap). A single laser pulse, or multiple asynchronous laser pulses, timed to match the trajectory of the target ion can be used. Light-based fragmentation techniques are known in the art. Applying these techniques to the μEST allows the emittance of the laser to be matched to the requirements for fragmentation.

[0021] Thus, the μEST can be operated to confine one or more precursor ions in a trapping region (which can first be analyzed and / or selected), fragment the one or more precursor ions, and then detect the fragment ions. Thus, MS / MS operation is possible in both data dependent (DDA) and data independent (DIA) acquisition modes. These steps can be repeated to provide MS n Operation. The use of non-destructive image current detection permits multi-stage analysis of single individual ions. Data-dependent decisions on ion fragmentation are also possible by controlling subsequent fragmentation based on the previous detection.

[0022] In another aspect, an array of microscale electrostatic ion traps (μESTs) may be provided, each ion trap having a longitudinal length of no more than 10 mm and / or at least one electrode (preferably a detection electrode) with a capacitance to ground of no more than 1 pF. Thus, each μEST can analyze a small number of ions, but for large arrays, parallel analysis on a significant scale is possible. This can improve overall throughput and sensitivity. Optionally, the capacitance to ground of one, some or each detection electrode is kept low, typically no more than (or less than) 1 pF, 500 fF, 100 fF, 50 fF, 10 fF, 5 fF or 1 fF.

[0023] The array typically has an inlet for receiving an ion beam, and a portion of the ion beam can be trapped in each μEST in the μEST. Each μEST in the array typically has a design according to the general details discussed above. Such an array may be particularly useful for peptide analysis, as will be discussed below. The same calibration mixture can be used for calibration of multiple μESTs in the array.

[0024] Specifically, the array may have a geometry based on one or more parallel planes, each plane being defined by two opposing substrates (wafers) with electrodes formed on these substrates opposite to each other, thereby defining one or more μESTs in the same plane. In other words, parallel wafers stacked in multiple levels may be used to form traps to achieve massively parallel operation. This may be advantageous because a single laser pulse may be able to fragment ions in multiple trapping regions. Additionally or alternatively, three or more substrates may define multiple different planes, each with one or more μESTs. In the case of fragmentation caused by a UV or IR laser, a beam splitter device may be used to spatially divide the laser pulse output into different planes. A lens array (particularly using microlenses optionally with anti-reflection coatings) may then focus each portion of the pulse into a corresponding collimated beam.

[0025] In operation, ions from a single ion beam can be distributed to multiple μESTs in an array, which can then process the received ions in parallel. Statistical and / or machine learning methods can be applied to the detection output from the μESTs. This can help identify the components of a single ion beam. Optionally, chromogenic tags or tandem mass tags are used to improve the analysis.

[0026] Another aspect of analyzing an ion beam containing a mixture of different analyte ions may be considered. Ions from the ion beam are directed to a plurality of electrostatic ion traps in an array of electrostatic ion traps. Each trap has a longitudinal length of no more than 10 mm (and preferably less, as discussed above) and / or at least one electrode (preferably, a detection electrode) with a capacitance to ground of no more than 1 pF (and preferably less, as discussed above). Mass and charge data about the ions may then be obtained from the plurality of traps, preferably by at least some simultaneous analysis (e.g., by analysis of the ions and / or derivatives of the ions). The mass and charge data may be combined to identify the components of the mixture. The process may be performed by a computer control and may be implemented in a computer program for execution by a processor of a mass spectrometer configured to control such an array of electrostatic ion traps or including such an array.

[0027] Advantageously, the ions (and / or their derivatives) can be fragmented in the trap. Precursor ions and / or fragment ions can be analyzed to advantageously obtain mass and charge data from multiple traps and multiple degrees of fragmentation. The MS / MS operation can be extended to MS by repeated fragmentation. n Operations, as discussed above. Other features and / or aspects discussed herein may also be implemented within the method.

[0028] Higher productivity, sensitivity and dynamic range are possible according to all aspects of the present disclosure. Combinations of various aspects and / or features from within various aspects are possible. Further benefits may be obtained by combining various aspects of the present disclosure with ion sorting equipment (e.g., ion mobility analysis followed by an ion trap array). BRIEF DESCRIPTION OF THE DRAWINGS

[0029] The present disclosure may be put into practice in many ways and a preferred embodiment will now be described by way of example only and with reference to the accompanying drawings, in which:

[0030] Figure 1A Schematically illustrates a basic design for a μEST according to an embodiment;

[0031] Figure 1B The method for implanting ions is shown in FIG. Figure 1A Example distribution of the potential of μEST along the z dimension;

[0032] Figure 2A A schematic diagram showing a second embodiment of the μEST in the plane of a set of electrodes;

[0033] Figure 2B Shows the vertical plane Figure 2A implementation plan;

[0034] Figure 3A An example signal induced on the detection electrode of the μEST of Figure 2 in the absence of noise is plotted;

[0035] Figure 3B Depicted is the simulated spectrum of a single positive charge oscillating within the μEST of Figure 2 with thermal noise;

[0036] Figure 4 illustrates an example wafer having electrodes formed thereon at different magnification levels, showing edge roughness significantly less than 10 nm;

[0037] Figure 5 schematically depicts μEST in three consecutive operation steps;

[0038] Fig. 6A A wafer stack including a plurality of μESTs is shown;

[0039] Figure 6B Depicted Fig. 6A to illustrate ion fragmentation by radiation according to one embodiment;

[0040] Figure 7 shows a schematic layout of the wafer and electrical connections for a single row of wells within the array;

[0041] Figure 8Schematic diagram illustrating the experimental setup for testing and using the μEST array;

[0042] FIG9 schematically depicts two planar electrostatic trap electrode designs, wherein (a) shows a side view applicable to both designs, (b) shows a top view of a first design with a straight (or single curved) electrode interface, and (c) shows a top view of a second design with a wavy electrode interface;

[0043] Fig.10 The electrostatic potential along a boundary generated by a sinusoidally varying electrode interface in one example is plotted for four different distances from the boundary;

[0044] Figure 11 plots the distance from the electrode as it increases. Fig.10 The change in electrostatic potential generated by the sinusoidal electrode interface is shown;

[0045] FIG12 shows different curved electrode interfaces, specifically: (a) a sinusoidal variation of the boundary between electrodes; (b) a square wave interface with curvature of the boundary midline; and (c) an elongated strip electrode design with a modulated duty cycle along the longitudinal axis of the well;

[0046] Fig.13 The electrostatic field induced along the boundary by straight and sinusoidally varying electrode interfaces is plotted for four different interface lengths;

[0047] Fig.14A The out-of-plane electric field along the midline of a planar electrostatic trap for an axially misaligned trap with a sinusoidally varying electrode interface is plotted for four different interface lengths;

[0048] Fig. 14B The out-of-plane electric field along the centerline of a planar electrostatic trap for an axially misaligned trap with a square-wave varying electrode interface is plotted for four different interface lengths;

[0049] Fig.15 The boundary potential due to the square-wave-type electrode interface is plotted;

[0050] Fig.16 The electrostatic potential generated by the strip electrode design is plotted for four different displacements from the electrode boundary;

[0051] Fig.17A The electrostatic potential of the strip electrode design at (a) the boundary and (b) the midline is plotted for an example with a linearly increasing duty cycle;

[0052] Fig. 17BPlotted are the electrostatic potentials for a strip electrode design at (a) the boundary and (b) the midline for an example with a linearly increasing duty cycle, where the arcs are engineered into the induced midplane potential by adjusting the duty cycle variation that shifts each strip;

[0053] Fig.18 The electrostatic potential along the centerline of the well due to the strip electrode design of Figure 12(c) is plotted;

[0054] Fig.19 Depicted for an electrostatic trap design based on electrodes held at only two different potentials: (a) the boundary potentials of the electrodes with a positive voltage electrode, a ground electrode, and a negative voltage electrode; (b) the potential induced in the midplane of the trap. (c) the potential along the midline of the trap;

[0055] Fig. 20 schematically illustrates a method for aligning two substrates of a μEST based on balls positioned in grooves; and

[0056] Fig.21 Schematic structures are illustrated for an alternative method for alignment, in which surface metallization is deposited on a dielectric interlayer. DETAILED DESCRIPTION

[0057] The present disclosure provides a new type of electrostatic ion trap having a longitudinal length not exceeding (and preferably less than) 10 mm. This is called a microscale electrostatic trap (μEST), and in some specific implementations, the longitudinal length may not exceed (or be less than) 5 mm, 2 mm, or 1 mm. Such an electrostatic ion trap may be formed by a set of planar electrodes (preferably, two sets of opposing planar electrodes (parallel to each other)). Such electrodes may be reliably formed to have nanometer tolerances, for example, using photolithography techniques. Therefore, μEST may be suitable for confining and / or analyzing a small number of ions, for example, less than 10 ions or even a single ion. The advantageous design of μEST will be further discussed herein.

[0058] The use of electrostatic potential for capture and / or analysis allows high-resolution accurate mass analysis. By image current measurement, non-destructive and reliable detection is possible even if detection of a single elementary charge is allowed. The smaller size of μEST is conducive to the detection of a single elementary charge. In fact, the image current signal V induced by the charge q is proportional to q / C, where C is the capacitance between the detection electrodes (which is in turn roughly proportional to the size of the detection electrodes). For detection electrodes less than 1 mm, this produces an image current signal V in the μV range (i.e., less than 1 mV and typically significantly less than 1 mV, but typically above 100 nV). It is advantageous to keep the capacitance of the detection electrode to ground less than 1 pF and typically significantly smaller (e.g., 500 fF, 100 fF, 50 fF, 10 fF, 5 fF or 1 fF). At the same time, the noise of modern transistors used to amplify the signals from those detection electrodes can be made much lower than 10 nV / √Hz. In addition, the capacitance of those transistors can also be made lower than (or at least approximately) the detection electrode capacitance C.

[0059] The inventors have realized that with this low noise level it is possible to achieve acquisitions over a duration of 10 ms to 100 ms with a charge determination accuracy better than one elementary charge (ē=1.602*10 -19 Coulombs). This allows not only the determination of the mass-to-charge ratio of ions, but also their charge and therefore their mass directly, without using, for example, isotope distribution. This in turn provides the opportunity for high-throughput analysis of individual ions.

[0060] The μEST array provides the opportunity to analyze a large number of ions simultaneously without the limitations of a single channel and without the bulk of the instrument. The particularly advantageous design of the μEST permits a space-efficient array and can also allow parallel fragmentation of ions, as will be described below. MS / MS and MS n Analysis is thereby also possible.

[0061] Thus, the present disclosure substantially overcomes the problems caused by the single-channel nature of HR / AM mass spectrometers. Parallel operation of large numbers (e.g., thousands) of μESTs (each μEST having a throughput of 10 to 100 analyses per second) permits new modes of operation. For example, multiple fractions may be pre-separated by such ion storage arrays. Higher analytical specificity is also possible.

[0062] This method is different from known microscale RF traps. These microscale RF traps include US8362421, US8835839, Tolmachev et al. Anal. Chem. 86 18 9162-9168 (2014), WO2017062102, US9984861, US8975578, US8841611. Although the dimensions of the ion traps may be similar to those described herein (and some of the manufacturing techniques may overlap), the structure of the traps is different and different voltages are applied.

[0063] First reference Figure 1A , schematically illustrates a basic design for μEST according to an embodiment. μEST 10 includes a first set 20 of electrodes and a second set 30 of electrodes. Both the first set 20 of electrodes and the second set 30 of electrodes are planar. For example, the first set 20 of electrodes may include a substrate 22 (e.g., a wafer) and an electrode 25 formed on the substrate 22 (e.g., using photolithography). Similarly, the second set 30 of electrodes may include a substrate 32 (which may also be a wafer) and an electrode 35 formed on the substrate 32. Electrodes 25 and 35 are elongated in a plane perpendicular to the plane of the drawing (in other words, extending in a width dimension). The height and (sometimes) width are typically smaller than (and preferably significantly smaller than) the length. Using two relative sets of electrodes D can provide a high-quality electric field.

[0064] Also shown is the longitudinal axis 40 of the μEST 10 (which longitudinal axis can be considered to define the 'z' dimension). Therefore, the electrodes 25 and 35 can be considered to be distributed along the longitudinal axis 40, and their width dimension (along the 'x' axis) is therefore perpendicular to the longitudinal axis 40 (and not completely in the plane of the drawing). As mentioned above, the maximum length of the μEST 10 along the longitudinal axis 40 does not exceed 10mm, preferably does not exceed 2mm, and more preferably does not exceed 1mm. The gap between the two sets 20, 30 of electrodes defines a height dimension (along the 'y' axis), which can be set by using precision spacers (not shown).

[0065] Electrode 25 and electrode 35 each have a corresponding function, wherein the first set of electrodes 20 and the second set of electrodes 30 have the same function in the two opposite electrodes. Two central electrodes D are used for ion detection. At least some of the electrodes are configured to receive an electrostatic potential for limiting the received ions. The outermost electrode R is used for reflection of ions (ion mirror), and a suitable DC potential is applied to these electrodes. The electrode between the detection electrode D and the reflection electrode R is an accelerating electrode A, and a suitable electrostatic potential is applied to these accelerating electrodes for accelerating ions and for spatial focusing of these ions. An example ion trajectory 45 is shown, whereby ions are confined within the capture region of μEST 10, which is formed in the gap between the first set of electrodes 20 and the second set of electrodes 30.

[0066] Next reference Figure 1B , showing the target for implanting ions Figure 1A Example distribution of potential along the z dimension of the μEST. In this mode of operation, the voltage at the entrance of the trap (applied to the reflecting electrode R) is reduced to allow a small group of ions of interest (which can optionally be of a pre-selected mass) to enter. The voltage applied to the reflecting electrode R is then raised to the reflecting level before the ions return to the entrance to provide the trapping mode. Figure 1A , an injection from the top along the z-axis is shown. After the voltage applied to the reflective electrode R is increased (causing the trap to close) and the ion trajectory stabilizes, detection is performed using the detection electrode D. An on-chip differential amplifier 50 receives the image current from the detection electrode D. The resulting signal is routed toward multiplexing and signal processing electronics, some of which may be off-chip. For example, a portion of the signal processing may also be implemented on the same circuit, while the remaining one or more portions of the signal processing are performed on an application specific integrated circuit (ASIC) or a field programmable gate array (FPGA).

[0067] Detection is therefore performed non-destructively based on the image current, and thus multi-stage mass analysis becomes possible, as will be discussed further below. The smaller size of the trap (typical gaps between electrodes are less than 50 μm to 100 μm) facilitates significantly lower capacitance of the detection electrodes compared to existing electrostatic traps. This achieves single charge sensitivity and also allows both the charge and mass-to-charge ratio of individual ions to be measured simultaneously. In this respect, the electrostatic trap can be considered to be similar to the conical trap described, for example, in DZ Keifer, EE Pierson, MF Jarrold, Analyst, Vol. 142, p. 1654 (2017), but is characterized by a much higher sensitivity and greater independence of the oscillation period on the initial parameters of the incident ions.

[0068] The use of a well scaled to sub-millimeter dimensions (as shown in Figure 2) produces oscillation frequencies in the range of approximately 1 MHz to 10 MHz. This enables resolution capabilities in the range of 30,000 to 100,000 for peptide ion accelerations of 100 V to 200 V with measurement times of less than 20 ms. -7 mbar(10 -5 Mean free paths greater than 100 m can be achieved under vacuum of 1000 Å (Pa). It will be appreciated that the frequency spread of the ions of interest, and therefore the accuracy of the mass determination, is related to the tolerances of the design (flatness, parallelism, line accuracy, etc.). The exact relationship may depend on the beam and optics.

[0069] In the general sense of the present disclosure and according to one aspect, an electrostatic ion trap may be considered, comprising: a first set of planar electrodes, the first set of planar electrodes being distributed along the longitudinal axis of the ion trap; and a second set of planar electrodes, the second set of planar electrodes being distributed along the longitudinal axis of the ion trap, each of the electrodes in the second set being arranged to be spaced apart from and opposite to a corresponding electrode in the first set. The length of the first set of planar electrodes and the second set of planar electrodes along the longitudinal axis is advantageously no greater than 10 mm (and optionally no greater than 5 mm, 2 mm, 1 mm or 0.5 mm). Additionally or alternatively, at least one of the electrodes (preferably one, some or each detection electrode) has a capacitance to ground of no greater than 1 pF. Advantageously, at least some of the electrodes in the first set and the second set are configured to receive an electrostatic potential for confining ions received in the space between the first set of planar electrodes and the second set of planar electrodes. The electrostatic ion trap may be configured to receive no more than 100 (optionally 50, 40, 30, 20, 10 or 5) ions injected into the electrostatic ion trap, and preferably, the electrostatic ion trap is configured to receive a single ion injected into the electrostatic ion trap. A controller and / or processor may be provided to control the operation of the electrostatic ion trap and / or receive one or more outputs from the electrostatic ion trap. A computer program including instructions for implementing the operating method as disclosed herein may be configured to operate on such a processor.

[0070] Corresponding methods of manufacturing and / or operating such an electrostatic ion trap (e.g., including methods of analyzing an ion beam) are also contemplated, the methods having steps of forming and / or providing and / or using features of the device. For example, the first set of electrodes and the second set of electrodes may be manufactured by photolithography.

[0071] Preferably, at least one of the electrodes (and more preferably some of the electrodes) is a detection electrode configured to detect an image current of the confined ions. By using such a smaller electrostatic trap size (as discussed above), it is possible to detect the image current with a resolution better than 1 elementary charge. One or more detection electrodes may be positioned along the longitudinal axis toward the center of the ion trap. The capacitance of one, some or each detection electrode to ground is advantageously kept low, typically not exceeding 1pF, 500fF, 100fF, 50fF, 10fF, 5fF or 1fF. This is achievable and / or advantageous even in the absence of a longitudinal length of no more than 10mm, but the parameters can be closely connected.

[0072] In one embodiment, some of the electrodes are reflective electrodes configured to receive a reflected potential. The reflective electrodes are advantageously located at the ends of the ion trap along the longitudinal axis. In an embodiment, the potential on the reflective electrodes is selectively configured to be at: a lower level to allow ions to enter the ion trap; and a higher level to confine ions to the ion trap.

[0073] Optionally, some of the electrodes are accelerating electrodes configured to receive an accelerating potential.The accelerating electrode is preferably located between the reflecting electrode and the detecting electrode along the longitudinal axis.

[0074] Advantageously, the first set of electrodes is formed on a first planar substrate. In an embodiment, the second set of electrodes is formed on a second planar substrate opposite to the first planar substrate. The first substrate and the second substrate may form part of an integrated circuit. The spacing between adjacent electrodes is preferably no more than 500 μm, 200 μm or 100 μm (and more preferably no more than 50 μm). One or more spacers may be provided between the first set of electrodes and the second set of electrodes. This may define the height of the device.

[0075] In an embodiment, the arrangement of the first set of electrodes is substantially symmetrical between opposite sides of the center of the electrostatic trap along the longitudinal axis. Additionally or alternatively, the arrangement of the second set of electrodes is substantially symmetrical between opposite sides of the center of the electrostatic trap along the longitudinal axis.

[0076] The electrostatic ion trap may be configured such that one or more of the following items are achieved: the measurement time does not exceed 20 ms; the acceleration voltage does not exceed 200 V; and the gas pressure in the electrostatic ion trap does not exceed 10 -7 mbar.

[0077] Details of specific embodiments will now be discussed.Further description of this and other general aspects according to the present disclosure will be provided below.

[0078] In practice, the Figure 1AThe electrode configuration shown is more complex to provide more optimized μEST properties with reduced spatial and time-of-flight aberrations. In this regard, reference is next made to Figure 2A , in which a schematic diagram of a second embodiment of a μEST in the plane of a set of electrodes is shown (using reference Figure 1A The dimensions discussed are in the xz plane, y=0). Also refer to Figure 2B , showing the vertical plane (yz plane, x = 0) Figure 2A implementation plan. Figure 2A and Figure 2B All dimensions are marked in mm and further in voltage (voltages and dimensions are rounded to the nearest figure).

[0079] Figure 2A and Figure 2B The design shown differs from the Figure 1A The design shown. First, a larger number of electrodes are provided, including a central electrode E0 between the central detection electrodes (D1, D2). Second, the shapes of the electrodes are different. The electrode on one side of the z=0 line has a roughly rectangular shape (in the xz plane), while the electrode on the other side of the z=0 line has a shape defined by an arc. The central electrode E0 has an edge defined by a straight line on one side of the z=0 line, and an edge defined by an arc on the other side of the z=0 line. The central electrode E0 acts as a curved lens, and some of the other curved electrodes have a reflector function. Nevertheless (and from Figure 2B As can be seen), the arrangement of electrodes on both sides of the z=0 line is symmetrical in other ways. Figure 2B As shown, the gap between all electrodes is 0.005 mm.

[0080] The edge of the center electrode E0 defined by the arc and the adjacent edge of the detection electrode D1 are both defined by concentric circles centered at z=-1. The radius of the edge of the detection electrode D1 is indicated as R1. The edges of all other electrodes on this side of the z=0 line (except the far edge of the end electrode) are defined by concentric circles centered at z=+5.3. The radius of the edge of the sixth electrode closest to the z=0 line is also indicated as R6. The curvature of the center electrode or curved lens E0 and the electrodes in the z<0 portion of the design (left side) keep the ions along the z axis. Otherwise, the ions may drift in the x direction (along the width of the trap). In addition, the curvature of the center electrode or curved lens E0 can compensate for the TOF aberration from the curvature of the left electrode. This curvature allows the ions to be well accommodated in the x direction, preferably within the x dimension of the detection electrodes D1 and D2. Instead of the curvature, it can also be used. Figure 2A Additional electrodes (not shown) are provided above and below the FET to provide this containment via fringe fields.

[0081] Also shown are the DC voltages applied to the electrodes. These voltages are applied symmetrically to the electrodes on either side of the z=0 line, and also symmetrically to the opposing electrodes in both sets, except for a potential U0 applied to the center electrode E0, which has a relative offset (labeled ±Δ) applied to the opposing electrodes for tuning.

[0082] Symmetry of the powered electrodes about each well is desirable (these are not shown, but are typically adjacent to the far edge of the electrodes shown in the x-dimension and extend in the z-dimension), at least where the well width in the x-dimension (width) does not exceed 8 times h (where h is the height of the well in the y-dimension, 60 μm in this example). Otherwise, uncompensated ion drift may occur in this direction, which may distort the time of flight. This may be particularly relevant in variant implementations in which only electrodes without curvature are used (e.g., as in Figure 2A , where z>0 and mirrored on the left). In this case, fringe fields can be used to restrict the motion of ions along the x dimension.

[0083] therefore, Figure 2A and Figure 2B The configuration shown shows a more advanced planar μEST geometry that confines ions in all directions while providing a resolving power of up to 100,000 (or less than 10 ppm mass accuracy) for ions with + / - 1% energy spread within the incident beam occupying 40% of the gap between the electrodes. It can be seen that this geometry combines a planar electrostatic mirror with a curved mirror and a curved cylindrical lens in between.

[0084] In operation, ions oscillate between electrodes receiving the U6 potential. The electrode receiving the U2 potential is the accelerating electrode. The electrodes receiving the potentials U3, U4, and U5 are finely tuned to reduce or minimize the higher order aberrations used for spatial and time-of-flight focusing. This can allow for a mass resolution that is one or more orders of magnitude higher than the mass resolution possible with the design of FIG. 1. In addition, demanding ion focusing properties (such as weak dependence on ion energy, angular spread, and / or beam size) are possible.

[0085] Reference now Figure 3A , plots an example signal induced on the detection electrode of the μEST of Figure 2 in the absence of noise. Also refer to Figure 3B, in which a simulated spectrum of a single positive charge oscillating within the μEST of FIG. 2 with thermal noise is depicted. The strongly anharmonic nature of the oscillations can be seen in these graphs, resulting in the first and third harmonics of the signal having similar amplitudes. Therefore, each ion can be detected at one or both of these frequencies, advantageously with a signal-to-noise ratio high enough to determine the charge of the ion from either harmonic. Such a signal can be obtained using low capacitance JFET transistors wire-bonded to a wafer (substrate), or using transistors fabricated in a single CMOS process using the wafers. In the case where the top and bottom wafers are separated by precision spacers, the first stage of amplification can occur on one or both wafers. The difference between the separations provided by the spacers for the same well is preferably less than 5%, 2%, 1% and most preferably no more than 0.5% or 0.2% of the ion beam size (e.g., the largest cross-sectional dimension, which in this example is about 40% of the gap h between the wafers). If the beam size is unknown, the range can correspond to approximately at least 0.1% and no more than 2% of the gap (h) between the wafers. For the well sizes considered in this disclosure, this may correspond to a parallelism of 0.1 μm to 1 μm.

[0086] In an advantageous embodiment, two detector plates facing each other may be connected by conductive precision spacers. These may be constructed by MEMS technology, for example near the sensitive area. In this case, one readout circuit may be used for a single detector unit. In the case of using non-conductive spacers, two separate readout circuits may be required for the upper and lower substrates of a single detector unit. In this case, the signals may be added electrically after amplification.

[0087] High resolution and mass accuracy are provided by high-order time-of-flight focusing within an electrostatic trap, combined with nanometer-scale fabrication precision on a planar wafer. Figure 4 , illustrates an example wafer with electrodes formed thereon at different magnification levels, showing edge roughness significantly less than 10 nm. This is particularly useful for very thin metallizations such as Figure 4The approximately 75 nm shown) can be more easily achieved. The high fidelity of edge definition by photolithography can determine the ion optical quality, final mass accuracy and mass resolution of μEST. Typically, the ratio of the gap size between the wafers to the accuracy of the edge of the gap between the electrodes (particularly between the reflecting electrode R and the accelerating electrode A and / or between the accelerating electrode A and the detecting electrode D) should be at least 1000, preferably at least 2000, 5000 or 7000, and most preferably at least or greater than 10000, 20000 or 50000. It is also expected that the two wafers are well aligned, particularly within at most 2% of the ion beam size and preferably within at most 0.5% of the ion beam diameter (in the example of the present disclosure, the ion beam diameter is about 40% of the gap h between the wafers). For the well sizes considered in the present disclosure, this corresponds to an alignment accuracy of 0.1 μm to 1 μm.

[0088] Mass accuracy in the parts per million range may allow narrowing down the list of candidate compounds from existing databases (eg, peptides in bottom-up proteomics).

[0089] Returning to the general meaning of the present disclosure discussed above, further optional features may be considered. For example, one or two edges (on the side of the electrode extending perpendicular to the longitudinal axis (i.e., in the width dimension)) of at least some of the electrodes may have an arc shape (and optionally, the two edges may have an arc shape, for example, defined by the same circle, or the edges may have an arc shape defined by different circles). Additionally or alternatively, at least some of the electrodes may have a curved shape, an arc shape (for example, this may be applied to reflective electrodes) or a circular or elliptical shape (for example, applied to detection electrodes, which may be based on two circular arcs). This may apply to electrodes that are only on one side of the center of the electrostatic trap along the longitudinal axis (z=0 line).

[0090] A central electrode may be provided between the central detection electrodes.The central electrode may be configured to act as an ion lens.Preferably, the central electrode has (in width dimension) at least one curved edge.

[0091] In an embodiment, a transistor (e.g., a FET or JFET) is connected to one or more detection electrodes. Advantageously, the transistor can be formed by photolithography and / or forms part of an integrated circuit. Preferably, the transistor is wire bonded to or integrated with a substrate, for example, by a CMOS manufacturing process. The capacitance of the transistor is preferably comparable (e.g., within an order of magnitude) to the capacitance between the detection electrodes and / or the capacitance between the detection electrodes and ground.

[0092] Where one or more spacers are provided between the sets of electrodes, at least one of the one or more spacers may be conductive for coupling at least one electrode on the first set of electrodes with at least one electrode on the second set of electrodes (e.g., the detection electrodes in each set). The parallelism of the spacers is preferably 0.1 μm to 1 μm.

[0093] In some implementations, ions can be selected by applying a pulse voltage to one of the reflective electrodes, thereby causing at least some ions (eg, unwanted ions) to leave the trap.

[0094] Advantageously, the ratio of the size of the gap between the planar substrates to the precision of the edges of the gaps between adjacent electrodes in the first set and / or the second set is at least 1000, preferably at least 2000, 5000 or 7000, and most preferably at least or greater than 10000, 20000 or 50000. Additionally or alternatively, the alignment of the planar substrates may be within a precision of 0.1 μm to 1 μm.

[0095] Before returning to the general sense of the present disclosure, further specific details will be discussed again.

[0096] It is possible to fragment the ions in the μEST by radiation techniques that can be adapted to the planar geometry of the μEST. Referring next to FIG5 , a μEST is schematically depicted in three sequential operating steps: a) precursor analysis; b) selection and fragmentation; and c) fragment analysis. This represents a simple form of multi-stage analysis. In step a), the ion trajectory 45 is the normal confinement pattern, as described above with reference to FIG5 . Figure 1A This allows analysis of the precursor ions. In step b), the ion trajectory 46 is affected by radiation from a focused ultraviolet (UV) or infrared (IR) laser pulse until ion fragments are formed (as discussed below). The resulting fragments are restored to a restricted trajectory 48 in μEST and reanalyzed in step c). The repetition of steps b) and c) achieves MS n operate.

[0097] UV photodissociation is commonly used in conventional mass spectrometry (see, for example, WO-2007 / 109672). Advantageously, UV photodissociation can be used to provide additional structural information about the ions within the μEST. The ions of interest (selected by adding a UV photodissociation electrode) can optionally be selected in step b) by pulsing down the voltage applied to the upper reflector electrode of the μEST to allow all unwanted ions to leave the trap. Figure 2A). When the ion of interest reaches the turning point 47, the ion is subjected to a focused pulse of UV light (e.g., from a 213nm Nd:YAG or 193nm ArF laser). For better selectivity, the timing of the UV pulses can be matched to the trajectory of the target ion. Alternatively, the timing can be asynchronous, but then multiple pulses can be used to increase the probability of radiation of the ion of interest (preferably to 100%). UV laser pulses with a duration of a few nanoseconds can easily produce fragmentation of most biologically relevant organic molecules (e.g., see JS Brodbelt et al., Chem. Rev. Vol. 120, p. 3328 (2020)). IR can be used instead of UV. As described above, the process of selection and fragmentation can be repeated several times, for example, depending on the probability of formation and capture of charged fragments (MS n Methods). Fragmentation in the inflection point may offer the advantage of minimizing the initial energy of the fragment ions, thus reducing energy spread and improving analytical precision.

[0098] Considering again the general significance of the present disclosure, further advantageous features may be considered. For example, the electrostatic ion trap may also include a UV or IR laser that is configured to emit pulses at the trapping region of the electrostatic ion trap, thereby fragmenting the ions confined in the trapping region. Advantageously, the laser may be configured to emit pulses in a direction orthogonal to the longitudinal axis of the electrostatic ion trap. In some embodiments, the laser is configured to emit a single laser pulse with timing that matches the trajectory of the target ion. Alternatively, the laser may be configured to emit multiple laser pulses that are asynchronous with the trajectory of the target ion.

[0099] The laser may be controlled for fragmentation of ions in the trapping region. The controller or processor may then receive signals from the detection electrodes for detecting ions fragmented in the trapping region. Preferably, detection and / or selection of ions is additionally performed prior to fragmentation.

[0100] Another embodiment of fragmentation may include the same UV laser used to illuminate the surface of the electrode 22 to emit electrons via the photo effect. This may allow other fragmentation methods of the general electron dissociation (ExD) type, such as electron capture dissociation (ECD), electron induced dissociation (EID), etc. A weak magnetic field from an external permanent magnet may be added to increase the residence time of the electrons in the trap and thus improve the efficiency of the fragmentation.

[0101] In a preferred embodiment, the electrostatic ion trap can be controlled to achieve repeated fragmentation and detection. Thus, MS can be provided in the electrostatic ion trap. n Operation. Optionally, fragmentation can be controlled in response to information determined from a previous detection. In this way data-dependent decision ion fragmentation can be achieved.

[0102] Before further discussing the general scope of the present disclosure, additional details of specific embodiments will be discussed again.

[0103] The design of μESTs at small scales and especially on substrates (e.g., wafers) allows for placement of a corresponding set of electrodes for each of the multiple wells on a single wafer. Using two such wafers, a two-dimensional array of wells can be produced. Thus, using three or more wafer stacks in multiple levels can provide multiple such two-dimensional arrays and permit a three-dimensional array of μESTs. In this way, a large number of μESTs can be provided in a small volume, making large-scale parallel operation possible.

[0104] Next reference Fig. 6A , shows a wafer stack including a plurality of μESTs. Each of the wafers may have electrodes formed on the top and bottom sides along the lines discussed above. The stack 80 includes a first wafer 81 and an adjacent second wafer 82 separated by a height of 50 μm.

[0105] Reference now Figure 6B , depicting Fig. 6A 1 to illustrate ion fragmentation by radiation according to a specific implementation. A plurality of ion confinement regions 100 are illustrated, each of which is defined by a corresponding μEST comprising separate electrodes formed on a wafer. Ions enter each μEST in the μESTs from the edge of the wafer along axes 110 (which are also the longitudinal axes of each μEST). Thus, N μESTs can be provided in a single row. Laser pulses 120 are directed along the plane of the ion confinement in a direction perpendicular to the axis 110 of ion entry. In this way, a single laser pulse 120 can be used to fragment ions in a plurality of μESTs simultaneously.

[0106] For an array of N wells in a row with M rows above each other, a single laser pulse can be split into M sub-beams, each of which is focused into a collimated beam by an array of micro-lenses with anti-reflection coatings. With N = 10 to 20, the wells span 5 mm to 10 mm, and the diameter of the beam can be maintained within the required 20 μm to 30 μm along the entire length and without contacting the electrodes. The angular divergence should be within about ±1 mrad to achieve this. At a fragmentation threshold of 1 mJ / mm for peptides 2 In the case of , pulse energies of less than 1 μJ per line may be required despite tight collimation.

[0107] Next reference Figure 7, in which a schematic layout of a wafer for a single row of wells within an array is shown. Eight wells are shown, including: a first well 131; a second well 132; a third well 133; a fourth well 134; a fifth well 135; a sixth well 136; a seventh well 137; and an eighth well 138. Each of these wells is spaced apart from one another, preferably with a distance of at least (or greater than) 6h between their longitudinal axes, most preferably at least (or greater than) 10h, where h represents the spacing between the wafers (in other words, the height of the well). Since the fringe field decreases exponentially as one moves away from the longitudinal axis of the well, anything at least about 3h away from the ions on the z-axis is unlikely to affect the field. For these reasons, transistors, wires, or the like used for image current detection, for example, may be so placed.

[0108] Figure 7 Also shown are conductors for connecting to the wells. Specifically, DC voltage lines 141, 142, 143, 144, 145, and 146 provide DC voltages to and between the wells (smaller, similar connecting lines are provided between adjacent wells, but these may not be clearly seen from the figure). Pulse signal lines 151, 152, 153, 154, 155, and 156 provide pulse signals to the wells (similar lines for providing pulse signals to other wells exist, but are not highlighted). Output signal line 160 (connected to the drain and source of the detection JFET) is also indicated.

[0109] Following standard mass spectrometry labeling (e.g., see P. Roepstofrf, J. Fohlman, Biomed. Mass Spectrom. 11 (11), 601 (1984)), most UVPD fragments of tryptic peptides are a-ions and y-ions, followed by x-species and z-species. Low-energy charged fragments formed during this pulse are usually accelerated back to μEST from the turning point, while uncharged fragments and unselected precursors are lost from the analysis. After capturing charged fragments and their accurate mass measurements in μEST, important structural information (sequence tags) about the ions of interest can be inferred to accurately locate the correct compound (e.g., peptide) for candidates from the library, which can be briefly listed after filtering for precursor mass.

[0110] For MS / MS and MS using μEST n Methods, modifications to existing tools used in conventional mass spectrometry may be desirable. First, the presence of only one isotope in the spectrum may lead to increased ambiguity, resulting in unknown isotopic abundances (e.g., 13 C or 15N). With multiple wells and higher throughput, the identification process can greatly benefit from the application of statistical and / or machine learning methods. The use of chromogenic tags attached to peptides can also be considered to increase the identification rate. TMT and TMTPro reporter ions can be used to analyze pooled samples.

[0111] The output of each μEST in the array can be digitized and processed individually. This allows the extraction of mass / intensity pairs. The intensity can be converted into an integer of the charge (charge state) of the ion. This allows the determination of mass from m / z measurements with low ppm accuracy. n The data can be correlated with the single-stage (MS) data of the precursor. This data can then be used for searching (e.g., in a database).

[0112] It is likely that each trap will detect only one isotopic molecule. In addition, the average number of fragments will generally be lower than in a conventional (large-scale) mass spectrometer. Therefore, the search space for any output data will generally be wider than in a conventional proteomic analysis. In contrast, the ability to directly associate fragments with precursors (because precursors will be single ions) can reduce the search space compared to large-scale proteomic analysis. Data from other traps may also be considered, such as using machine learning to better identify precursors.

[0113] μEST can be useful even without fragmentation. This can be useful, for example, if a particular sample can have different charge states for the same mass-to-charge ratio (m / z), such as in the case of analyzing intact proteins and top-down proteomics.

[0114] In the general sense of the present disclosure (which may be combined with or part of the general sense discussed above), an array of electrostatic ion traps may be considered, each ion trap having a longitudinal length of no more than 10 mm and / or having at least one of the electrodes (preferably one, some or all of the detection electrodes) having a low ground capacitance, typically no more than 1 pF (and optionally lower, as described above). The longitudinal length may optionally be no more than 5 mm, 2 mm, 1 mm or 0.5 mm. Advantageously, the array includes an entrance for receiving an ion beam, the entrance being configured such that a portion of the ion beam may be trapped in each of the ion traps. A controller and / or processor may be provided to control the operation of the array and / or receive one or more outputs from the array. In addition, a corresponding method of manufacturing and / or operating such an array of electrostatic ion traps may also be considered, the method having the steps of forming and / or providing and / or using the features of the device.

[0115] In one aspect, a method of analyzing an ion beam containing a mixture of different analyte ions may be considered. The method includes: directing ions from the ion beam to a plurality of electrostatic ion traps in an array of electrostatic ion traps (e.g., an array as discussed above and elsewhere herein, optionally including any features of the electrostatic ion traps described herein), each electrostatic ion trap having a longitudinal length of no more than 10 mm; obtaining signals indicating mass and charge data about ions from the plurality of electrostatic ion traps; and combining the mass and charge data obtained from the signals for use in identifying components of the mixture. The ion beam may be generated by a mixture of analytes.

[0116] The signal is advantageously obtained by analyzing the ions and / or derivatives of the ions. For example, the ions in each trap or their derivatives can be considered as precursor ions. The precursor ions can then be fragmented in a plurality of traps to obtain fragment ions. Obtaining the signal can include obtaining the signal by analyzing the precursor ions in a plurality of traps and / or obtaining the signal by analyzing the fragment ions in a plurality of traps. Then, combining the mass and charge data can combine the mass and charge data about the precursor ions and / or the mass and charge data about the fragment ions. Advantageously, the steps of fragmentation, obtaining the signal, and combining the mass and charge data are repeated in sequence (to achieve MS n operate).

[0117] Obtaining a signal may include analyzing ions in each of the plurality of traps simultaneously. This may include analyzing a collection of ions in the plurality of traps simultaneously and / or analyzing fragment ions in the plurality of traps simultaneously. Simultaneous fragmentation of ions in the plurality of traps is also possible.

[0118] According to this method aspect (and any other method aspect provided herein), a computer program may be provided, the computer program comprising instructions that, when executed by a processor, cause the processor to perform a corresponding method. For example, the processor may be configured to control an array of electrostatic ion traps (or a mass spectrometer comprising such an array). A (non-transitory) computer-readable medium comprising or storing such a computer program may also be provided.

[0119] Various options will now be considered based on any of the above aspects and / or specific implementations. For example, each electrostatic ion trap may be (and preferably is) an electrostatic ion trap according to any of those described above. For example, the electrostatic ion trap may include: a first set of planar electrodes, the first set of planar electrodes being distributed along the longitudinal axis of the corresponding ion trap; and a second set of planar electrodes, the second set of planar electrodes being distributed along the longitudinal axis of the corresponding ion trap, each electrode in the second set of electrodes being arranged to be spaced apart from and opposite to the corresponding electrode in the first set. The length of the first set of planar electrodes and the second set of planar electrodes along the longitudinal axis does not exceed 10 mm, and / or at least one electrode (preferably a detection electrode) may have a capacitance to ground of not more than 1 pF (and optionally lower, as described herein). At least some of the electrodes in the first set and the second set may be configured to receive an electrostatic potential for limiting ions received in the space between the first set of planar electrodes and the second set of planar electrodes.

[0120] In a preferred embodiment, the array is configured with multiple electrostatic ion traps in the same plane. Additionally or alternatively, multiple electrostatic ion traps may be provided in different planes. Where multiple electrostatic ion traps are provided in the same plane, a single laser pulse may be used to fragment the ions in the multiple electrostatic ion traps in the plane (specifically, the corresponding trapping regions of these electrostatic ion traps). A single laser pulse may also be used to fragment the ions confined in different planes. For example, a UV or IR laser configured to generate pulses may be provided. The beam splitter device may then be configured to spatially divide the generated pulses into a plurality of parts and guide each part along corresponding different planes. A lens array comprising a plurality of (micro) lenses may be used. Each lens is advantageously configured to focus a corresponding portion of the generated pulses into a corresponding collimated beam. An anti-reflection coating may be applied to the lens.

[0121] Ions may be received from a single ion beam at multiple electrostatic ion traps in an array. Ions received at multiple electrostatic ion traps may be processed in parallel (particularly where the ion beam includes ions of a peptide).

[0122] The detection output from each of the plurality of electrostatic ion traps may be provided to a processor.The processor may then be configured to apply statistical and / or machine learning methods to the detection output for identifying the composition of the single ion beam.

[0123] Ions may be injected from the same calibration mixture into multiple electrostatic ion traps in an array for calibration of the multiple electrostatic ion traps.

[0124] An ion beam including at least one ion having a chromogenic tag or a tandem mass tag may be sent to at least one electrostatic ion trap in the array.

[0125] Before further discussing the general scope of the present disclosure, additional details of specific embodiments will be discussed again.

[0126] Next reference Figure 8 , illustrates a schematic diagram of the experimental setup for testing the μEST array. This includes: an existing large-scale mass spectrometer 200 (produced by Thermo Fisher Scientific, Inc. as an Orbitrap TM Exploris TM 480 instrument); adapter chamber 300; and μEST array 400. Large-scale mass spectrometer 200 includes: high-capacity transfer tube 210; electrokinetic ion funnel 220; internal calibration source 230; active beam guide 240; quadrupole mass filter 250; ion gate 260; curved ion trap (C-trap) 270; orbital trap mass analyzer 280; ion routing multipole 290; and transmission multipole 295.

[0127] The adapter chamber 300 includes: a gate valve 310 ; an ion funnel 320 with a gas line 325 ; a Z lens (line of sight blocker) 330 ; an X,Y deflector 340 ; and a lens 350 .

[0128] Prior to an analytical run, each μEST can be calibrated using the same calibration mixture as the front-end instrument. In operation, the mass spectrometer's internal calibrant from source 230 can be used to monitor the mass accuracy of each well within the array and, if necessary, used as a lock mass.

[0129] In operation, each μEST is filled sequentially, for example in the grating (although parallel filling is possible). This can be achieved by pulsing the reflector electrode to receive ions of a specific m / z ratio (as discussed above with reference to FIG. 2, the pulse is added to the U6 potential). Thus, each μEST (due to its small size) can be used to detect a single charge.

[0130] The single-ion sensitivity even at high repetition rates allows μEST to measure even very low-abundance species within a mixture. This in turn enables deeper proteome coverage or similar situations. On the other hand, the small size of μEST that makes such ultrasensitive detection possible can also limit the number of ions analyzed to a maximum of a few dozen per injection.

[0131] Alternative designs for planar electrostatic ion traps based on modulated interfaces or wavy interfaces between adjacent electrodes are now also considered. These are applicable to any other design or specific implementation disclosed herein and / or can be combined therewith. Compared with the case of straight electrodes, the wavy interface between a pair of electrodes maintained at different potentials can have the effect of smoothing the transition between potential zones, and can provide improved control of the electrostatic field that limits ions. The design can also allow the ion trap to be tuned to obtain better performance, and can reduce the number of electrodes required under different potentials. In addition, these designs can help reduce the sensitivity of trap performance to the misalignment of electrode plates. This may be of particular concern in the assembly and operation of μEST.

[0132] Next, referring to Figure 9, two planar electrostatic trap electrode designs are schematically depicted, wherein (a) shows a side view applicable to both designs, (b) shows a top view of a first design with a straight (or single curved) electrode interface, and (c) shows a top view of a second design with a wavy electrode interface. The design in Figure 9(b) is a planar electrostatic trap design based on a straight electrode interface, as can be seen for a first set 301 of electrodes, a central electrode 302, and a second set 303 of electrodes. As discussed above, the electrodes are maintained at a carefully selected potential to produce a trapping field, while the pick-up electrodes measure the image charge induced by the ions. The axis of the trap is indicated by a dotted line along the z-axis.

[0133] As can be seen from Fig. 9 (a), the planar electrostatic ion trap comprises two relative plates of electrodes. As discussed above, each electrode is maintained at a fixed potential, and the combined electrostatic field of the electrodes limits the ions. In a multi-reflection design, ions are inserted along the axis of the trap by lowering and raising the gate electrode. Then, the ions are reflected between a pair of electrostatic mirrors at each end of the trap, thereby confining the ions for multiple cycles and enabling accurate measurement of the oscillation frequency.

[0134] The accuracy of mass-to-charge ratio predictions may be limited by variations in ion oscillation frequency (or equivalently, flight time) as a function of ion energy, insertion angle, and positioning. Therefore, to improve (or potentially) maximize the accuracy of mass-to-charge ratio predictions, the geometry and potential of each electrode are optimized to minimize variations in flight time due to uncontrolled experimental variables.

[0135] Conventional designs for planar electrostatic ion traps are based on a set of electrodes with uniform boundaries along the transverse axis of the trap (the transverse axis is the x-axis in Figure 9). Then, the potential and length of the electrodes can be carefully selected to minimize the variation of the flight time for the trajectory that is closely aligned with the axis of the trap. This optimization can be performed by Taylor expansion of the flight time about the main trajectory and minimizing the Taylor series coefficients (commonly referred to as aberration coefficients) about ion energy, angle, and positioning. This process can be continued to the highest possible order until the degrees of freedom provided by the electrodes are not enough to proceed further. More electrodes can be added to obtain additional degrees of freedom in this optimization process, however, the minimum electrode size limit and the number of required voltage supplies may soon become a problem.

[0136] Referring to Fig. 9 (c), a planar electrostatic trap utilizing a wavy electrode interface and strip electrodes is shown. It can be seen that the first set 311 of electrodes includes a high potential electrode 311a and a negative potential electrode 311b having a wavy interface therebetween. Similarly, the center electrode 312 includes a high potential electrode 312a and a negative potential electrode 312b having a wavy interface therebetween, and the second set 313 of electrodes includes a high potential electrode 313a and a negative potential electrode 313b having a wavy interface therebetween. A grounded pickup electrode 315 is also shown. Therefore, the design utilizes electrodes that are only maintained at three different potentials (high potential, negative potential, and ground).

[0137] In this method, the planar electrostatic trap design is extended by bending the interface between adjacent electrodes. Specifically, a wavy interface is introduced between adjacent electrodes. By doing so, the transition between potential zones can be effectively smoothed at the boundary. This is possible because the electrostatic potential in the trap is a convolution or blur of the potential at the boundary. Therefore, the use of electrode interfaces of arbitrary geometry can provide a greater degree of control over the electrostatic trapping field.

[0138] Designs utilizing these so-called wavy electrodes may have several advantages over designs using straight electrode geometries. First, since each electrode provides greater control over the electrostatic field, fewer electrodes may be required to achieve the same level of trapping performance. This may be particularly desirable in the design and construction of large arrays of μESTs, since fewer connections to external voltage sources are required.

[0139] The planar electrostatic ion trap may also be sensitive to the misalignment of the electrode plates, particularly to the relative displacement along the axis of the trap. This sensitivity may be driven by the sharp change of the electrostatic field along the axis. Therefore, when the electrode plates are not precisely aligned, an unbalanced electric field may be generated, which pushes the ions out of the plane of the trap (the plane is the xz plane in Figure 9). Due to this misalignment, the wavy electrode interface can make the sharp transition in the electrostatic field smooth and reduce the size of the out-of-plane electric field (the out-of-plane electric field is the y-axis in Figure 9). The high tolerance for optimal ion trap performance may make the construction and alignment of the electrode plates used for μEST challenging. Therefore, the wavy electrode interface is ideally suitable for this application.

[0140] The electrostatic fields generated by the wavy and straight electrode interfaces can be compared, as will now be discussed. It can be seen that small-scale interface features are rapidly suppressed as the distance from the boundary increases. In addition, the gradient of the electrostatic potential in the trap can be precisely controlled by changing the electrode interface. It can also be determined that when the electrode plates are misaligned, the wavy electrode interface generates a smaller out-of-plane electric field (the out-of-plane electric field is the y-axis in Figure 9).

[0141] The electrostatic field within the trap is determined by the potential along the boundary of the domain. If the designer can continuously change the potential at this boundary, then an arbitrary electrostatic field can be induced within the domain of the trap. In essence, this unrealistic level of control over the boundary potential can reproduce the electrostatic field induced by a three-dimensional collection of electrodes (e.g., a quadrupole director). Since the planar electrostatic trap design is limited to a discrete collection of electrodes at a fixed potential, this level of ultimate control cannot be achieved.

[0142] A well-known and interesting property of electrostatic fields (i.e., harmonic functions) is that each point within the domain is an average of the behavior of the field along the boundaries. Formally, the field at each point within a planar electrostatic well can be expressed as a convolution on the boundary potential. This convolution process acts as a blurring operation, so that the potential in the midplane of the electrostatic well is a blur of the boundary potential.

[0143] For example, consider a square wave variation of the boundary potential of a two-dimensional planar electrostatic well with wavelength λ and duty cycle 0 < α < 1. The peak-to-peak variation of the nth harmonic decays to,

[0144]

[0145] where n ≥ 1 and Δy is the displacement from the electrode boundary. This shows that the higher spatial frequencies of the boundary potential decay exponentially as the displacement from the boundary increases. It is noteworthy that for three wavelengths entering the domain, the contribution from each spatial frequency from the boundary decays by about 1 / 1000. Now refer to Fig.10, plots the electrostatic potential along the boundary generated by a sinusoidally varying electrode interface in one example for four different distances from the boundary. As the distance from the boundary increases, the electrostatic potential is generated by a sinusoidally varying electrode interface, where the wavelength λ = 12 μm and the transition length L 界面 =120μm. The well height is 60μn.

[0146] therefore, Fig.10 This blurring effect is illustrated, showing the electrostatic potential as the distance from the boundary electrode increases. This demonstrates that the sharp change in boundary potential almost completely disappears after a displacement of the order of a single wavelength.

[0147] Next, referring to FIG11 , the distance from the electrode is plotted as Fig.10 Figure 11(a) plots the standard deviation of the potential in the transverse x-direction along the longitudinal z-axis of the well. The “ideal” zero variation is also shown (the thick solid black line). Figure 11(b) plots the same data on a log-linear scale. It can be seen that as the distance from the electrode increases, the standard deviation quickly approaches the numerical simulation limit of ~10 -5 Thus, the standard deviation of the electrostatic field (i.e., the deviation from the "ideal" (constant) potential) is plotted as a function of distance from the electrode. By exploiting this fuzzy property of the electrostatic field, the ultimate control limit can be approached at the boundary potential described above using only a discrete set of electrodes.

[0148] Reference is now made to FIG. 12 , in which different curved electrode interfaces are shown, specifically: (a) a sinusoidal variation of the inter-electrode boundary; (b) a square wave interface with a curvature of the boundary midline; and (c) an elongated strip electrode design with a modulated duty cycle along the longitudinal axis of the trap. Thus, FIG. 12 (a) and FIG. 12 (b) illustrate additional levels of control of the electrostatic field provided by the wavy electrode interface. This is advantageous in the design of electrostatic traps that exhibit minimal changes in the flight time of ions with respect to energy, insertion angle, and positioning.

[0149] Next reference Fig.13 , plotted for four different (increasing) interface lengths L 界面 , The electrostatic field induced along the boundary by straight and sinusoidally varying electrode interfaces, for comparison. The well height was taken to be 60 μm. This demonstrates enhanced control, showing that the gradient of the electrostatic potential can be tuned using the length of the electrode interface.

[0150] Then refer to Fig.14A , in which the interface lengths L are plotted for four different (increasing) 界面 , for an axial misalignment trap with a sinusoidally varying electrode interface (Δd 轴向=1.0 μm) along the center line of the planar electrostatic well (x=y=0) y The well height is taken as 60 μm. Fig. 14B , in which the out-of-plane electric field along the centerline of a planar electrostatic trap for an axially misaligned trap with a square-wave varying electrode interface is plotted for four different interface lengths for Fig.14A Therefore, in Fig.14A and Fig. 14B The same parameters are used in both.

[0151] Reference now Fig.15 , plotting the boundary potential due to the square wave electrode interface. Another benefit of the wavy electrode interface is that it reduces the magnitude of the out-of-plane electric field (the out-of-plane electric field is the y-axis in FIG9 ) induced by the misalignment of the electrode plates along the longitudinal direction of the well. Fig.14A , Fig. 14B and Fig.15 Shown in.

[0152] The concept of a wavy electrode interface can be extended to co-linear electrode strips held at different potentials. This is specifically shown in Figure 12(c), for example. By varying the duty cycle of the strips in the lateral direction of the well, the effect of varying between intermediate potentials along the boundary can be established.

[0153] Next reference Fig.16 , plotted for four different displacements Δy from the electrode boundary 边界 Electrostatic potential generated by the strip electrode design. The wavelength of the strip design is λ=15μm and the duty cycle is periodically varied between 0.1≤α≤0.9. The well height is taken to be 60μm. The figure shows the electrostatic potential and the boundary potential due to the collection of strip electrodes as the displacement from the boundary increases, illustrating that the features of the individual strips are suppressed exponentially as the displacement into the well increases.

[0154] Reference now Fig.17A , where the electrostatic potential of a strip electrode design at (a) the boundary and (b) the midline is plotted for an example with a linearly increasing duty cycle. Specifically, the duty cycle increases from α = 0.1 → 0.85 over 180 μm. The wavelength of the strip design in (b) is λ = 15 μm. The potential is induced in the midplane of the well. The well height is 60 μm.

[0155] Further references Fig. 17B, where the electrostatic potential of a strip electrode design at (a) the boundary and (b) the midline is plotted for an example with linearly increasing duty cycle, where arcs are engineered into the induced mid-plane potential by adjusting the duty cycle variation of the shifted each strip. Specifically, the duty cycle increases from α=0.1→0.85 over 180μm. The wavelength of the strip design in (b) is λ=15μm. The potential is induced in the mid-plane of the well. The well height is 60μm.

[0156] Also refer to Fig.18 , plotting the electrostatic potential along the centerline of the well due to the strip electrode design of FIG12( c ). Fig.17A , Fig. 17B and Fig.18 We show that this principle can be used to fabricate electrostatic lenses of arbitrary shapes and potential gradients.

[0157] Next reference Fig.19 , depicts the following for an electrostatic trap design based on electrodes held at only two different potentials: (a) the boundary potentials of the electrodes with a positive voltage electrode, a ground electrode, and a negative voltage electrode; (b) the potential induced in the midplane of the trap. (c) The potential along the midline of the trap. This corresponds to the design shown in Figure 9(c).

[0158] The strip electrode design principle can significantly reduce the number of different electrode potentials required for the fabrication and operation of high-performance electrostatic ion traps. Fig.19 Thus, an electrostatic trap design requiring only two non-grounded electrode potentials is outlined. This design can reproduce the electrostatic field induced by the straight electrode array of FIG. 9( b), which uses electrodes maintained at six different non-grounded potentials. Due to the strict constraints in the manufacture and operation of these devices, reducing the required number of different potentials can present significant advantages in the construction of high-performance microscale electrostatic ion traps.

[0159] Figure 9(c) and Fig.19 The design outlined in is merely an example of a strip electrode technique and should not be construed as the only possible concept. Furthermore, the strip electrode approach can be easily extended to designs that use only a single non-grounded electrode potential.

[0160] Another benefit of the strip electrodes may be enhanced control of the electrostatic potential within the trap. Thus, these strip electrodes may allow the design of electrostatic traps with small flight time variations for ions with different energies, insertion angles, and positioning. As an example of this design process, assume that a specific potential is required along the centerline of the trap (Figure 9, x=0, y=0), represented by ψ(z). Since the electrostatic field within the trap is determined by the boundary potentials, the required potential can be expressed as a convolution,

[0161] ψ(z)=φ(0,0,z)=∫dx′∫dz′K(xx′,yy′,zz′)f(x′,z′)| x＝0,y＝0 ,

[0162] where K(x,y,z) is the kernel and f(x,z) is the yet-to-be-determined boundary potential. Along the transverse x-axis, each strip electrode can be determined by the duty cycle α(z) at that longitudinal location. This allows the boundary potential to be expressed in terms of the unknown duty cycle as

[0163] f(x,z)=S(x / λ;α(z)),

[0164] where S(x;α) is a square wave of unit period and duty cycle α. Substituting this equation into the previous equation, for unknown duty cycle, the first kind of nonlinear Fredholm integration problem can be formulated as

[0165]

[0166] where the nonlinear kernel is given by

[0167] T(z,α)=∫dx′K(x′,y,z)S(x′ / λ,α)| y＝0 .

[0168] Fast Fourier transform techniques can allow fast evaluation of the convolution forms given in these latter two expressions. This can allow a solution to the duty cycle to be developed by discretizing and using standard regularization methods for the first kind of Fredholm integration problem. An example is the regularized nonlinear least squares formula,

[0169]

[0170] where the minimization is taken on a finite dimensional basis B and μ is a regularization parameter.

[0171] Returning to the general meaning of the present disclosure discussed above, further details may be considered. For example, the boundary between at least some of the electrodes adjacent to each other may have a wavy, modulated or multi-bent shape. In some specific implementations, at least some of the electrodes are strip electrodes. Then, the duty cycle of the strip electrodes may change along the longitudinal axis of the ion trap. Optionally, the strip electrodes may be configured to define a lens. In this case, the strip electrodes may be configured to remain at different electrostatic potentials. In an embodiment, the electrostatic potential received by at least some of the electrodes in the first set and the second set of electrodes for limiting ions may be a single non-zero electrostatic potential. Optionally, the electrostatic potential received by at least some of the electrodes in the first set and the second set of electrodes for limiting ions may be a discrete number of different non-zero electrostatic potentials, typically 2 or 3 different non-zero electrostatic potentials.

[0172] An alternative implementation of the μEST will now be considered (which may be combined with any other implementation disclosed herein). As described above, the μEST is advantageously manufactured using microlithography and / or nanolithography techniques to achieve tolerances in the nanometer range on a planar wafer. The detection electrodes advantageously have a low capacitance (less than 1 pF) to allow single charge detection. Each electrode set is formed on a planar substrate, and the two substrates are opposed to each other to form a well or a linear arrangement of wells.

[0173] As previously described, the structures on each side are separated by spacers (in the z direction), which may typically have a size of 60 μm. These structures are aligned in the planar direction (perpendicular to the separation direction, i.e., the x and y directions) with an accuracy of better than 0.5 μm and a parallelism of better than 0.5 μm at the system level. Achieving this accuracy is challenging. High-precision positioning tools can be used, but these tools typically require special expertise and a time-consuming alignment process is completed at the chip level. The method described below utilizes a self-alignment method that uses high-precision silicon anisotropic etching combined with a dielectric substrate.

[0174] Silicon can be etched with high precision using potassium hydroxide (KOH) or tetramethylammonium hydroxide (TMAH) solutions. These anisotropic processes exploit the single crystal properties of silicon. The (111) plane in the single crystal is the natural etch stop in the process. In a standard silicon (100) wafer, the (111) plane is oriented at 54.735° from the surface. When rectangular shapes are masked and etched by such solutions, inverted pyramids or V-shaped grooves are produced. The angles of these V-shaped grooves have atomic precision. However, the positioning of the grooves is limited by the photolithography steps. The basis of these etching processes is described in "KOH anisotropic silicon etching for MEMS accelerometer fabrication", Petteri Kilpinen, Doctoral thesis Department of Materials Science and Engineering, Aalto University (2012).

[0175] For precision balls, this inverted pyramid appears to be perfectly pitched. Such balls are available in many materials (such as sapphire, alumina or stainless steel) with diameters greater than 0.2 mm, variations from perfect shape less than 0.08 μm, and batch diameter variations less than 0.13 μm (see " –mit Maximalnote", Datasheet, Saphirwerk).

[0176] Next reference Fig. 20 , schematically shows a method for aligning two substrates of μEST based on balls positioned in grooves (particularly, V-grooves). A first groove or pitch 401 is provided in a first substrate, and an opposite second groove or pitch 402 is provided in a second substrate. A precision ball 403 positioned between the first spacing 401 and the second spacing 402 forms a precise alignment system. When a force orthogonal to the substrate plane is applied, the two wafers are precisely aligned with each other in all dimensions. The method is similar to the method disclosed in US-5,639,387, but the method disclosed in US-5,639,387 is used for alignment in optical applications.

[0177] Various techniques can be used to permanently fix the substrate in this position. Suitable bonding techniques may include, for example, gluing, welding or thermocompression bonding. The accuracy is limited by the accuracy of the ball, the etching depth and the photolithography.

[0178] The gap g between the substrates can be calculated by the following equation.

[0179]

[0180] Where g represents the gap distance between the substrates, d represents the depth of the groove, and r represents the ball ( Fig. 20 ), and α represents the orientation angle of the (111) plane.

[0181] With a suitable sphere (e.g. a sapphire sphere with a radius of 150 μm + / - 0.125 μm) and a precise groove etch with a depth of, e.g., 229.8 μm + / - 0.5 μm, a gap accuracy of 60 μm + / - 1.5 μm can be achieved. When using V-grooves, the etch rate is reduced by a factor of 400 when the (111) planes fall together. In this case, the accuracy of the depth is primarily defined by the lithography rather than by the etch rate. Even better parallelism is expected, since the etch depth and lithography at the chip level are much better than at the wafer level.

[0182] The lateral accuracy may depend on the accuracy of the lithography. This may allow the use of a lateral accuracy of better than 0.5 μm of a stepper.

[0183] In this method, alignment is performed at the chip level, but alignment can also be performed at the wafer level. When alignment is performed at the chip level, a minimum of three balls per chip can be used to define lateral positioning and form a stable gap. At the wafer level, three balls per chip or a minimum of three balls per wafer can be used.

[0184] These fixtures can be applied after alignment to fix the alignment position of the wafers. These connections can also be used to form electrical connections between wafers.

[0185] Variations on this general alignment method are also possible. Anisotropic dry etching techniques can be used to form precise spacing. Fibers can be used instead of balls with similar results. Any object with a precise spacing size that matches the spacing size of the grooves may be suitable. Silicon is preferred for the reasons given above, but alternatives may be considered, using appropriate substrate materials for which etching of grooves of suitable precision is possible.

[0186] Although the method is based on the use of silicon as a substrate, this may cause other problems. The silicon substrate may result in high parasitic capacitance of the detection pad, which may make single ion detection difficult. That is, other materials may not allow anisotropic etching techniques. With this in mind, another method may be to deposit a surface metallization layer on a dielectric intermediate layer (e.g., SiO2 or SiN4) with a thickness of up to several μm on silicon. In other words, the dielectric layer is inserted between the silicon substrate and the surface metallization. When the silicon is etched, the dielectric layer can remain in place. This can reduce parasitic capacitance while allowing alignment by silicon etching, as described above. Therefore, the method can be combined with alignment techniques based on silicon etching.

[0187] Reference now Fig.21 , illustrates a schematic structure for an alternative method for alignment, in which surface metallization is deposited on a dielectric interlayer. This effectively shows a cross section in the xy plane, showing a silicon substrate 410 from which a portion 415 has been removed from the back side (under the critical structure) using anisotropic etching. Metal features are aligned 440 from the top silicon substrate to the bottom silicon. The substrate is etched to an oxide layer 430 to meet the low capacitance required for the detection area. Electrical contacts 420 are provided for connection purposes.

[0188] Based on a combination of techniques, this approach allows precise alignment along with desired electrical properties to form an improved electrostatic trap with single-ion sensitivity.

[0189] Although embodiments according to the present disclosure have been described with reference to specific types of equipment and applications (specifically, mass spectrometry) and these embodiments have specific advantages in this case, as discussed herein, methods according to the present disclosure can be applied to other types of equipment and / or applications. Specifically, devices according to the present disclosure can be used for other applications. Although the specific structure, arrangement and operating details (e.g., parameters) of μEST and / or μEST arrays may be advantageous (especially in view of known configurations and capabilities), there may be great changes to achieve an operating mode with similar or identical performance. The scale of μEST may also vary widely, such as from nanometers to millimeters. Certain features may be omitted or replaced, such as shown herein. Unless otherwise stated, each feature disclosed in this specification may be replaced with an alternative feature for the same, equivalent or similar purpose. Therefore, unless otherwise stated, each feature disclosed is only an example of a series of equivalent or similar attribute features.

[0190] In the detailed description of various embodiments, for the purpose of explanation, many specific details are set forth to provide a thorough understanding of the disclosed embodiments. However, those skilled in the art will appreciate that these various embodiments may be practiced with or without these specific details. Furthermore, those skilled in the art can readily appreciate that the specific order in which the methods are presented and executed is illustrative, and it is contemplated that the order may be changed and still remain within the scope of the various embodiments disclosed herein.

[0191] Although Figure 1A The basic design for μEST is shown, but some modifications are possible. For example, it may not be necessary to have two detection electrodes on each substrate. In an alternative approach, the detection electrode may be provided on only one substrate. The detected signal may thus be halved, but the capacitance is also reduced (which may affect noise pickup), so the signal-to-noise ratio may only be reduced by √2. As another alternative, a single detection electrode may be used. This is less preferred because two electrodes are better for differential detection and common mode rejection.

[0192] The number and positioning of the accelerating and / or reflecting electrodes may vary. It is desirable to use at least one accelerating electrode and at least one reflecting electrode on each side (in the z dimension) of each set of electrodes (i.e., four accelerating electrodes and four reflecting electrodes). In some configurations, fewer accelerating electrodes may be used. With different designs of μEST, the number of reflecting electrodes may also be reduced.

[0193] A variety of fabrication techniques may be used including: glass on silicon, low temperature silicon, wafer polishing, precision alignment techniques, and similar fabrication techniques.

[0194] Variations of the μEST shown in reference FIG2 may also be considered. For example, the number of electrodes and / or the applied potential may be significantly changed. The curvature of the electrodes in the design of FIG2 is only on the electrodes in the z<0 portion (left side), but in some implementations, other electrodes (at z>0 or on the right side) may be curved. The number of possible variations of this basic design is essentially unlimited.

[0195] As used herein, including in the claims, unless the context indicates otherwise, the singular form of the terms herein should be interpreted as including the plural form, and vice versa. For example, unless the context indicates otherwise, a singular reference herein (including in the claims), such as "one / kind" (such as an ion multipole device) means "one or more" (for example, one or more ion multipole devices). In the specification and claims of the present disclosure, the words "include", "comprising", "having" and "containing" and variations of these words, for example, "including" or similar words mean "including but not limited to", and are not intended to (and do not) exclude other components. In addition, the use of "or" is inclusive, so that when "A" is true, "B" is true, or "A" and "B" are both true, the phrase "A or B" is true.

[0196] The use of any and all examples or exemplary language ("for example," "such as," "for example," and similar language) provided herein is intended to merely better illustrate the present disclosure and does not indicate a limitation on the scope of the present disclosure unless otherwise required. No language in this specification should be construed as indicating any non-claimed element essential to the practice of the present disclosure.

[0197] The terms "first" and "second" can be reversed without changing the scope of the present disclosure. That is, an element referred to as a "first" element can instead be referred to as a "second" element, and an element referred to as a "second" element can instead be considered a "first" element.

[0198] Unless otherwise specified or the context requires otherwise, any steps described in this specification may be performed in any order or simultaneously. In addition, where a step is described as being performed after a step, this does not exclude intermediate steps being performed.

[0199] It should also be understood that, unless otherwise implicitly or explicitly understood or stated, for any given component or embodiment described herein, any possible candidate or alternative listed for that component may generally be used alone or in combination with each other. It should be understood that any list of such candidates or alternatives is merely illustrative and not restrictive, unless otherwise implicitly or explicitly understood or stated.

[0200] All literature and similar materials cited in this disclosure (including but not limited to patents, patent applications, articles, books, treaties, and internet web pages) are expressly incorporated by reference for any purpose. Unless otherwise defined, all technical and scientific terms used herein have the meaning commonly understood by one of ordinary skill in the art to which the various embodiments described herein belong.

Claims

1. An electrostatic ion trap, comprising: a first set of planar electrodes, the first set of planar electrodes being distributed along a longitudinal axis of the ion trap; a second set of planar electrodes distributed along the longitudinal axis of the ion trap, each of the electrodes in the second set being arranged to be spaced apart from and opposite to a corresponding electrode in the first set; wherein at least some of the electrodes in the first set and the second set are configured to receive an electrostatic potential for confining ions received in a space between the first set of planar electrodes and the second set of planar electrodes; and Wherein the length of the first set of planar electrodes and the second set of planar electrodes along the longitudinal axis does not exceed 10 mm, and / or wherein the capacitance of at least one of the electrodes to ground does not exceed 1 pF.

2. The electrostatic ion trap of claim 1, wherein at least one of the electrodes is a detection electrode configured to detect an image current of the confined ions, and wherein the capacitance of the detection electrode to ground does not exceed 1 pF.

3. The electrostatic ion trap according to claim 2, wherein: some of the electrodes are reflection electrodes configured to receive a reflection potential, the reflection electrodes being located at ends of the ion trap along the longitudinal axis; and Some of the electrodes are accelerating electrodes configured to receive an accelerating potential, the accelerating electrodes being located between the reflecting electrode and the detecting electrode along the longitudinal axis.

4. The electrostatic ion trap of claim 3, wherein the potential on the reflective electrode is selectively configured to be at: a lower level to allow ions to enter the ion trap; and a higher level to confine the ions to the ion trap. 5 . The electrostatic ion trap according to claim 2 , further comprising a transistor connected to the detection electrode.

6. An electrostatic ion trap according to any preceding claim, wherein the first set of electrodes is formed on a first planar substrate and the second set of electrodes is formed on a second planar substrate opposite the first planar substrate.

7. An electrostatic ion trap according to any preceding claim, wherein the gap between adjacent electrodes does not exceed 100 μm.

8. An electrostatic ion trap according to any preceding claim, wherein the first substrate and the second substrate form part of an integrated circuit, or wherein the first set of electrodes and the second set of electrodes are fabricated by photolithographic techniques.

9. An electrostatic ion trap according to any preceding claim, wherein the arrangement of the first set of electrodes is substantially symmetrical along the longitudinal axis between opposite sides of the center of the electrostatic trap, and wherein the arrangement of the second set of electrodes is substantially symmetrical along the longitudinal axis between opposite sides of the center of the electrostatic trap.

10. An electrostatic ion trap according to any preceding claim, wherein one or both edges of at least some of the electrodes have an arcuate shape, or at least some of the electrodes have a curved, arcuate, circular or elliptical shape.

11. An electrostatic ion trap according to any preceding claim, wherein the boundaries between at least some of the electrodes adjacent to each other have a wavy, modulated or multiply curved shape.

12. An electrostatic ion trap according to any preceding claim, wherein at least some of the electrodes are strip electrodes having a duty cycle that varies along the longitudinal axis of the ion trap.

13. An electrostatic ion trap according to any preceding claim, wherein at least some of the electrodes are strip electrodes configured to define a lens, the strip electrodes being configured to be held at different electrostatic potentials.

14. An electrostatic ion trap according to any preceding claim, wherein the electrostatic potential received by at least some of the electrodes in the first and second sets for confining ions is a single non-zero electrostatic potential.

15. The electrostatic ion trap of any preceding claim, further comprising one or more spacers between the first set of electrodes and the second set of electrodes.

16. The electrostatic ion trap of claim 15, wherein at least one spacer of the one or more spacers is electrically conductive for coupling at least one electrode on the first set of electrodes with at least one electrode on the second set of electrodes.

17. An electrostatic ion trap according to any preceding claim, wherein the electrostatic ion trap is configured such that one or more of the following items are achieved: a measurement time does not exceed 20 ms; an acceleration voltage does not exceed 200 V; and a gas pressure within the electrostatic ion trap does not exceed 10 -7 mbar.

18. An electrostatic ion trap according to any preceding claim, configured to receive no more than 100 ions injected into the electrostatic ion trap.

19. An electrostatic ion trap as claimed in any preceding claim when dependent on claim 3, arranged to select ions by applying a pulsed voltage to one of the reflective electrodes, thereby causing at least some of the ions to leave the trap.

20. An electrostatic ion trap according to any preceding claim, further comprising: A UV or IR laser configured to emit pulses at a trapping region of the electrostatic ion trap to fragment ions confined in the trapping region.

21. The electrostatic ion trap of claim 20, wherein the laser is configured to emit the pulses in a direction orthogonal to a longitudinal axis of the electrostatic ion trap.

22. An electrostatic ion trap according to claim 20 or claim 21, wherein the laser is configured to: emit a single laser pulse with timing matching the trajectory of the target ion; Alternatively, multiple laser pulses may be fired asynchronously with the trajectory of the target ion.

23. The electrostatic ion trap according to any one of claims 20 to 22, further comprising: A controller is configured to control the laser to fragment ions in the trapping region and receive signals from the detection electrode for detecting ions fragmented in the trapping region.

24. The electrostatic ion trap of claim 23, wherein the controller is further configured to control the repetition of fragmentation and detection to provide MS in the electrostatic ion trap. n operate.

25. The electrostatic ion trap of claim 24, wherein the controller is configured to control fragmentation in response to information determined from a previous detection.

26. An array of electrostatic ion traps, each ion trap having a longitudinal length not exceeding 10 mm and / or at least one electrode with a capacitance to ground not exceeding 1 pF, the array comprising an entrance for receiving an ion beam, the entrance being configured so that a portion of the ion beam can be trapped in each ion trap in the ion traps.

27. The array of claim 26, wherein each electrostatic ion trap comprises: a first set of planar electrodes, the first set of planar electrodes being distributed along a longitudinal axis of a corresponding ion trap; a second set of planar electrodes distributed along the longitudinal axis of the respective ion trap, each of the electrodes in the second set being arranged to be spaced apart from and opposite to a corresponding electrode in the first set; wherein at least some of the electrodes in the first set and the second set are configured to receive an electrostatic potential for confining ions received in a space between the first set of planar electrodes and the second set of planar electrodes; and The lengths of the first set of planar electrodes and the second set of planar electrodes along the longitudinal axis do not exceed 10 mm, and / or at least one of the electrodes in the first set and the second set has a capacitance to ground of not more than 1 pF.

28. An array according to claim 26 or claim 27, wherein the array is configured with multiple electrostatic ion traps in the same plane and / or multiple electrostatic ion traps in different planes.

29. The array of any one of claims 26 to 28, further comprising: a UV or IR laser configured to generate pulses; a beam splitter arrangement configured to spatially split the generated pulse into a plurality of portions and to direct each portion along a respective different plane; as well as A lens array includes a plurality of lenses, each lens being configured to focus a respective portion of the generated pulses into a respective collimated light beam.

30. An array according to any one of claims 26 to 29, the array being configured to receive ions from a single ion beam at a plurality of electrostatic ion traps in the array and to process the received ions in parallel at the plurality of electrostatic ion traps.

31. An array according to any one of claims 26 to 30, further comprising: A controller is configured to control delivery of an ion beam including at least one ion having a chromogenic tag or a tandem mass tag to at least one electrostatic ion trap in the array.

32. A method of analyzing an ion beam comprising a mixture of different analyte ions, the method comprising: directing ions from the ion beam to a plurality of electrostatic ion traps in an array of electrostatic ion traps, each electrostatic ion trap having a longitudinal length not exceeding 10 mm and / or at least one electrode with a capacitance to ground not exceeding 1 pF; obtaining signals indicative of mass and charge data regarding the ions from the plurality of electrostatic ion traps; as well as The mass and charge data obtained from the signals are combined for use in identifying components of the mixture.

33. The method according to claim 32, further comprising: fragmenting precursor ions in the plurality of electrostatic ion traps to obtain fragment ions; wherein the step of obtaining a signal indicative of mass and charge data comprises obtaining a signal by analyzing the precursor ions in the plurality of electrostatic ion traps, and / or obtaining a signal by analyzing the fragment ions in the plurality of electrostatic ion traps; and The step of combining the mass and charge data comprises combining the mass and charge data about the precursor ions and / or the mass and charge data about the fragment ions.

34. The method of claim 33, wherein the steps of fragmenting, acquiring a signal, and combining the mass and charge data are repeated sequentially.

35. The method of any one of claims 32 to 34, wherein the step of obtaining a signal comprises simultaneously analyzing ions in each of the plurality of electrostatic ion traps.

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