Physical ion filter apparatus using modulated RF electric field

Abstract

The present invention relates to a physical ion filter device using a modulated RF electric field. By selectively separating or selecting ions generated from specific gas components in an atmospheric pressure or low vacuum environment based on ion mobility characteristics, it overcomes the limitations of the existing FAIMS method that relies on a fixed asymmetric electric field and DC compensation voltage scan, enables high-speed and high-precision odor identification, significantly improves the accuracy and versatility of gas identification, and has the effect of being applicable to various application fields with only software-based parameter control without hardware replacement.

Description

Technology Field

[0001] The present invention relates to a physical ion filter device using a modulated RF (Radio Frequency) electric field. Background Technology

[0002] Generally, technologies for selectively detecting gases or volatile substances in the atmosphere have long been studied in various fields such as industrial safety, environmental monitoring, and process control.

[0003] Since such gas detection technology involves a diverse range of target substances and rapid changes in concentration, a detection device that simultaneously satisfies high selectivity, reproducibility, reliability, and rapid response characteristics is required.

[0004] Conventional gas detection technologies widely known include, for example, chemical sensors such as semiconductor gas sensors, metal oxide (MOX) sensors, and electrochemical gas sensors, or biological receptor-based biosensors.

[0005] However, the above chemical sensor has a large variation in sensitivity depending on changes in ambient temperature and humidity, low selectivity for various volatile organic compounds (VOCs), and a short lifespan or reduced reliability when used repeatedly for a long period due to degradation of the sensor sensing layer or consumption of the electrolyte.

[0006] Furthermore, although the aforementioned biological receptor-based biosensor exhibits excellent selectivity for specific substances, its commercialization is constrained by the difficulty of continuous measurement and high maintenance costs due to issues with receptor detachment characteristics and biochemical stability.

[0007] As an alternative to overcome these limitations, physical ion filter-based gas detection technology utilizing the mobility characteristics and electrical responses of ions in the atmosphere is attracting attention, and a representative example is Field Asymmetric Ion Mobility Spectrometry (hereinafter referred to as 'FAIMS').

[0008] However, one of the biggest technical challenges in conventional ion mobility-based analysis technologies like the aforementioned FAIMS is the ion clustering phenomenon caused by changes in the external environment, particularly changes in humidity.

[0009] Ions generated in an atmospheric pressure environment combine with highly polar water vapor molecules through electrostatic attraction to form clusters, which are large molecular aggregates. This clustering phenomenon distorts the intrinsic mobility characteristics of the ions by altering their effective size and mass.

[0010] In particular, in the case of FAIMS technology that utilizes the mobility difference between high and low electric fields, water vapor binding destabilizes the nonlinear mobility characteristics of ions, resulting in irregular shifts in measurement peaks or a rapid decrease in resolution.

[0011] Consequently, conventional technology often requires gas drying devices or strict temperature control to ensure analytical reproducibility, which imposes limitations on device miniaturization and portable applications.

[0012] In addition, conventional FAIMS technology uses a method of applying a high voltage with an asymmetric waveform between two electrodes and separating target ions by scanning a DC compensation voltage (CV) to compensate for the resulting nonlinear mobility difference of the ions.

[0013] However, since the ion separation performance of this method depends absolutely on the strength of the electric field, a high voltage of about 1 kV or more is typically applied to secure high resolution, which causes reliability problems of the device such as arc discharge when the system is miniaturized.

[0014] Furthermore, conventional FAIMS methods have limitations in precise individual separation in complex mixed gas environments because the controllable variables are very restricted to asymmetric electric field amplitudes and DC compensation voltages, resulting in low degrees of freedom. Additionally, there is a limitation in that measurements take a long time because high-speed scanning of the DC compensation voltage (CV) cannot be performed due to the problem of post-switching delay time whenever the CV is changed.

[0015] Therefore, there is a continuous demand for a new type of physical ion filter technology that overcomes the limitations of conventional methods based on high voltage dependence and limited control degrees of freedom, is more robust to environmental changes, and can precisely control ion selection characteristics. Prior art literature

[0016] Korean Patent Publication No. 10-2014-0056175 (Published May 9, 2014) The problem to be solved

[0017] The present invention has been devised to solve the aforementioned problems, and the objective of the present invention is to provide a physical ion filter device using a modulated RF electric field that can overcome the limitations of the existing FAIMS method, which relies on a fixed asymmetric electric field and DC compensation voltage (CV) scan, by selectively separating or selecting ions generated from specific gas components in an atmospheric pressure or low vacuum environment based on ion mobility characteristics, and can not only achieve high-speed and high-precision odor identification but also dramatically improve the accuracy and versatility of gas identification and be applicable to various application fields through software-based parameter control without hardware replacement.

[0018] In other words, the present invention aims to overcome the limitations of the prior art described above and, in implementing next-generation physical ion filter technology, specifically solve the following technical problems.

[0019] First, we aim to provide a low-voltage driven physical ion filter device capable of solving the problems of device enlargement and reduced reliability caused by high-voltage driving.

[0020] Second, the aim is to significantly improve the low analytical degrees of freedom resulting from the limited control variables of conventional technology, thereby securing high-resolution ion discrimination capabilities even in ion or mixed gas environments with similar mobility.

[0021] Third, we aim to provide a device with excellent analytical reproducibility by mitigating ion clustering phenomena caused by changes in the external environment, such as temperature and humidity.

[0022] Fourth, by moving away from the fixed DC compensation voltage (CV) scan method of conventional technology and using multidimensional parameter modulation, we aim to solve the post-switching delay problem of conventional technology and provide high-speed analysis responsiveness.

[0023] Fifth, we aim to suppress leakage current generated during device operation and simultaneously ensure driving stability and reliability through the miniaturization of the device. means of solving the problem

[0024] To achieve the aforementioned objective, one aspect of the present invention provides a physical ion filter device that is positioned on a path through which ions generated from a sample gas pass to selectively separate ions, comprising: a plurality of RF electrodes that form an electric field on the path of movement of ions; and an RF driver that superimposes one main RF electric field and at least one sub RF electric field to form a modulated RF electric field and applies the modulated RF electric field to the plurality of RF electrodes, wherein the RF driver controls parameters of the main RF electric field and each sub RF electric field so that the movement behavior or trajectory stability of ions is changed by the modulated RF electric field to selectively separate target ions.

[0025] Here, it is preferable that the RF driver controls the characteristics of the modulated RF electric field by controlling at least one parameter among the voltage amplitude, frequency, duty ratio, phase, and waveform of the main RF electric field and each sub-RF electric field individually or in conjunction with one another.

[0026] Preferably, each sub-RF electric field can be set to have a voltage amplitude lower than the voltage amplitude of the main RF electric field.

[0027] Preferably, the RF driver can variably control the separation resolution of ions by a combination of at least one parameter among the voltage amplitude, frequency, duty ratio, phase, and waveform of each sub-RF electric field without increasing the voltage amplitude of the main RF electric field.

[0028] Preferably, each sub-RF electric field may include a low-frequency component or a high-frequency component alone or in combination relative to the main RF electric field.

[0029] Preferably, the RF driver can form the modulated RF electric field by superimposing it on the main RF electric field with capacitive coupling for the high-frequency band component according to the frequency band of each sub-RF electric field, and can form the modulated RF electric field by superimposing it on the control terminal signal of the switching circuit that generates the main RF electric field for the low-frequency band component.

[0030] Preferably, each sub-RF electric field may include at least one waveform among a sine wave, a square wave, a triangular wave, a sawtooth wave, and any other waveform.

[0031] Preferably, the RF driver can control the characteristics of fine perturbation caused by the modulated RF electric field by selectively applying the waveform of each sub-RF electric field in response to the separation characteristics of the target ion.

[0032] Preferably, the RF driving unit can be controlled so that micro-perturbs caused by the modulated RF electric field are repeatedly accumulated during the residence time of the ion passing between the plurality of RF electrodes, and can be controlled so that the ion's movement trajectory is dynamically stabilized through the accumulation of micro-perturbs, thereby forming consistent ion separation characteristics despite changes in the external environment.

[0033] Preferably, the RF driving unit can operate in a single-phase driving mode by controlling the modulated RF electric field to be applied to a first electrode group among the plurality of RF electrodes and controlling the second electrode group opposite the first electrode group to maintain a preset reference potential, thereby forming a time-varying electric field distribution between the plurality of RF electrodes by the modulated RF electric field.

[0034] Preferably, the RF driving unit operates in an inverse phase driving mode by generating a pair of modulated RF electric fields having a phase difference of 180 degrees from each other and applying them in inverse phase to adjacent electrode groups among the plurality of RF electrodes, and through the inverse phase driving mode, the individual voltage amplitude introduced into the plurality of RF electrodes relative to an external reference potential is reduced, while leakage current according to the impedance characteristics of the device is suppressed, and the trajectory control efficiency of the ions is improved.

[0035] Preferably, the ratio (L / d) of the RF electrode length (L) formed along the ion movement direction to the spacing (d) between the plurality of RF electrodes can be configured to have a range of 10 to 50. Effects of the invention

[0036] According to the physical ion filter device using the modulated RF electric field of the present invention as described above, by selectively separating or selecting ions generated from specific gas components in an atmospheric pressure or low vacuum environment based on ion mobility characteristics, the limitations of the existing FAIMS method, which relies on a fixed asymmetric electric field and DC compensation voltage (CV) scan, can be overcome, and high-speed and high-precision odor identification can be achieved, as well as the accuracy and versatility of gas identification can be dramatically improved, and there is an advantage that it can be applied to various application fields with only software-based parameter control without hardware replacement.

[0037] In addition, according to the present invention, high resolution can be achieved through low-voltage driving. That is, unlike conventional FAIMS technology which had to excessively increase the voltage of the asymmetric RF to improve resolution, the present invention enables precise ion separation by fine perturbation through the control of a sub-RF with a low voltage amplitude without increasing the voltage of the main RF, thereby reducing the power consumption of the device, effectively suppressing the risk of electrical discharge, and providing advantages for miniaturization.

[0038] Furthermore, according to the present invention, the maximization of analytical degrees of freedom can be achieved. That is, control parameters such as voltage, frequency, duty cycle, phase, and / or waveform of the main RF and sub-RF electric fields can be independently adjusted, thereby providing multidimensional degrees of control freedom even for ions with similar mobility or complex gas components that were difficult to separate with conventional technology, which has the advantage of significantly improving identification capability.

[0039] Furthermore, according to the present invention, high-speed response and reduced measurement time are possible. That is, unlike conventional methods that continuously scan a DC compensation voltage (CV) under a fixed asymmetric electric field, the present invention forms ion passage conditions by selectively changing parameters of the modulated RF electric field, thereby reducing response delay after condition switching and enabling relatively fast measurement. Accordingly, there is an advantage that the total measurement time can be reduced even when performing continuous measurements while sequentially changing multiple ion selection conditions.

[0040] In addition, according to the present invention, high ion transmission efficiency and separation performance can be secured even in a miniaturized device environment. That is, the present invention optimizes the ratio of RF electrode length to RF electrode spacing (L / d) and applies a modulated RF electric field with a 180-degree inverse phase, thereby stably maintaining the trajectory of ions in the central region of the electrodes. Accordingly, even if the device is miniaturized, losses due to ion collisions with the electrodes can be minimized, and there is an advantage of simultaneously securing high transmission efficiency and resolution even under short travel distance conditions.

[0041] Furthermore, according to the present invention, leakage current suppression and device stability can be ensured. In particular, by suppressing leakage current caused by stray capacitance within the device through an inverse phase driving mode, precise electric field control with suppressed signal distortion is possible even in high-frequency modulation environments, and there is an advantage of enhancing the reliability of the entire device and / or system.

[0042] In addition, according to the present invention, robustness against environmental changes and reproducibility of analysis can be secured. That is, the present invention has the advantage of minimizing fluctuations in ion transport characteristics due to changes in external humidity by mitigating the effects of clustering phenomena between ions and water vapor molecules caused by fine perturbations of a modulated RF electric field. Brief explanation of the drawing

[0043] FIG. 1 is an overall configuration diagram for explaining a physical ion filter device using a modulated RF electric field according to one embodiment of the present invention. FIG. 2 is a diagram showing a structure in which an RF driver and an RF electrode are connected in a single-phase driving mode in an embodiment of the present invention. FIG. 3 is a diagram showing a structure in which an RF driver and an RF electrode are connected in an inverse phase driving mode in an embodiment of the present invention. Specific details for implementing the invention

[0044] The aforementioned objectives, features, and advantages are described in detail below with reference to the attached drawings, and accordingly, a person skilled in the art to which the present invention pertains will be able to easily implement the technical concept of the present invention. In describing the present invention, detailed descriptions of known technologies related to the present invention are omitted if it is determined that such descriptions may unnecessarily obscure the essence of the present invention.

[0045] Terms including ordinal numbers, such as first, second, etc., may be used to describe various components, but said components are not limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the first component may be named the second component, and similarly, the second component may be named the first component. The terms used in this application are used merely to describe specific embodiments and are not intended to limit the present invention. A singular expression includes a plural expression unless the context clearly indicates otherwise.

[0046] The terms used in this invention have been selected based on currently widely used general terms, taking into account their functions within the invention; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. Additionally, in specific cases, terms have been arbitrarily selected by the applicant, and in such cases, their meanings will be described in detail in the relevant description of the invention. Therefore, the terms used in this invention should be defined not merely by their names, but based on their meanings and the overall content of the invention.

[0047] When a part of a specification is described as "including" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "...part" or "module" as used in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware or software, or as a combination of hardware and software.

[0048] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the embodiments of the present invention exemplified below may be modified in various different forms, and the scope of the present invention is not limited to the embodiments described below. The embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art.

[0049] Combinations of each block of the attached block diagram and each step of the flowchart may be executed by computer program instructions (execution engines), and since these computer program instructions may be loaded into the processor of a general-purpose computer, a special-purpose computer, or other programmable data processing equipment, the instructions executed through the processor of the computer or other programmable data processing equipment create means to perform the functions described in each block of the block diagram or each step of the flowchart. Since these computer program instructions may also be stored in computer-available or computer-readable memory that can be directed toward the computer or other programmable data processing equipment to implement the function in a specific way, the instructions stored in computer-available or computer-readable memory may also produce a manufactured item containing instruction means to perform the function described in each block of the block diagram or each step of the flowchart.

[0050] And, since computer program instructions can be loaded onto a computer or other programmable data processing equipment, instructions that execute a computer or other programmable data processing equipment by performing a series of operation steps on the computer or other programmable data processing equipment to create a process executed on the computer can also provide steps for executing the functions described in each block of the block diagram and each step of the flowchart.

[0051] Additionally, each block or each step may represent a module, segment, or part of code containing one or more executable instructions for executing specific logical functions, and it should be noted that in some alternative embodiments, the functions mentioned in the blocks or steps may occur out of order. For example, two blocks or steps described in succession may actually be performed substantially simultaneously, and the blocks or steps may also be performed in the reverse order of the corresponding functions as needed.

[0052] First, a physical ion filter device using a modulated RF electric field according to one embodiment of the present invention includes a plurality of RF electrodes (100) disposed on an ion movement path, and an RF driving unit (200) that applies a modulated RF electric field in which one main RF electric field and at least one sub RF electric field are superimposed on the plurality of RF electrodes (100).

[0053] The present invention is centered on applying a fine perturbation to an ion passing between a plurality of RF electrodes (100) through a modulated RF electric field in which multidimensional parameters such as frequency, duty cycle, phase, and / or waveform (e.g., sine wave, square wave, triangular wave, sawtooth wave, any waveform, etc.) are independently controlled, thereby inducing a dynamic response including resonant operation for a specific ion species and selectively forming a trajectory stability accordingly to precisely separate a target ion.

[0054] In addition, the modulated RF electric field-based control of the present invention can contribute to improving analysis reproducibility by mitigating the ion clustering effect caused by humidity changes, which was a problem of the prior art, as the micro-perturbation is continuously applied on the ion migration path.

[0055] Furthermore, by optimizing the geometric ratio (L / d) of the RF electrode and using an inverse phase driving method, it is possible to achieve miniaturization of the device and low-voltage, high-efficiency operation, making it applicable as a source technology for portable gas analysis devices and various ion separation systems.

[0056] FIG. 1 is an overall configuration diagram for explaining a physical ion filter device using a modulated RF electric field according to an embodiment of the present invention, FIG. 2 is a diagram showing a structure in which an RF driver and an RF electrode are connected in a single-phase driving mode applied to an embodiment of the present invention, and FIG. 3 is a diagram showing a structure in which an RF driver and an RF electrode are connected in an inverse-phase driving mode applied to an embodiment of the present invention.

[0057] Referring to FIGS. 1 to 3, a physical ion filter device using a modulated RF electric field according to one embodiment of the present invention comprises, but is largely composed of a plurality of RF electrodes (100) and an RF driving unit (200), etc. Meanwhile, since the components shown in FIGS. 1 to 3 are not essential, the physical ion filter device using a modulated RF electric field according to one embodiment of the present invention may have more components or fewer components.

[0058] Hereinafter, the components of a physical ion filter device using a modulated RF electric field according to one embodiment of the present invention will be examined in detail as follows.

[0059] A plurality of RF electrodes (100) are positioned on the path of movement of ions and perform the function of forming an RF electric field on the path of movement of ions.

[0060] It is preferable that the ratio (L / d) of the RF electrode length (L) formed along the ion movement direction to the spacing (d) between these multiple RF electrodes (100) be in the range of about 10 to 50.

[0061] In one embodiment, when the ratio (L / d) is less than about 10, the effective residence time affected by the modulated RF electric field while the ion passes between the plurality of RF electrodes (100) is relatively insufficient, and thus the ion separation and selectivity may tend to decrease.

[0062] Conversely, if the above ratio (L / d) exceeds about 50, the perturbation effect caused by the electric field accumulates excessively, which may result in some ions being unable to pass smoothly between the electrodes, and consequently, the overall detection sensitivity may be reduced.

[0063] Accordingly, in one embodiment according to the present invention, by applying the above ratio (L / d) range to the design of a plurality of RF electrodes (100), the perturbation effect caused by the modulated RF electric field can be induced to accumulate without excessive during the residence time when ions pass between the plurality of RF electrodes (100), and accordingly, the ion separation characteristics and detection sensitivity can be formed in a balanced manner.

[0064] Meanwhile, a physical ion filter device using a modulated RF electric field according to one embodiment of the present invention has a structure in which a sample gas introduced from the outside is ionized through a separate ionization means (not shown) before being introduced.

[0065] At this time, the method of ionizing the sample gas may include, for example, a method using a radiation source such as Americium-241 (Am-241) or Nickel-63 (Ni-63), a UV lamp method using high-energy ultraviolet rays, or a corona discharge method, and the ions generated in this way may enter into a plurality of RF electrodes (100) applied in one embodiment of the present invention by means of a constant flow rate or potential difference.

[0066] And, the RF driving unit (200) forms a modulated RF electric field by superimposing one main RF electric field (Main RF) and at least one sub RF electric field (Sub RF), and performs the function of applying the formed modulated RF electric field to a plurality of RF electrodes (100).

[0067] This RF driving unit (200) can selectively separate target ions by controlling the parameters of the main RF electric field and each sub RF electric field, thereby changing the movement behavior and / or trajectory stability of the ions by the modulated RF electric field.

[0068] Additionally, the RF driving unit (200) can perform the function of controlling the characteristics of the modulated RF electric field by controlling at least one parameter among the voltage amplitude, frequency, duty ratio, phase, and / or waveform of the main RF electric field and each sub RF electric field individually or in conjunction with each other.

[0069] Additionally, the RF driving unit (200) can perform the function of variably controlling the separation resolution of ions by a combination of at least one parameter among the voltage amplitude, frequency, duty ratio, phase, and / or waveform of each sub-RF electric field without increasing the voltage amplitude of the main RF electric field.

[0070] At this time, it is preferable that each sub-RF electric field be set to have a voltage amplitude lower than the voltage amplitude of the main RF electric field. That is, each sub-RF electric field is set to have a voltage amplitude lower than the voltage amplitude of the main RF electric field, so that the separation resolution of target ions can be variably controlled by only a combination of parameters without applying high voltage.

[0071] In one embodiment, the voltage amplitude of the main RF electric field can be set to a level of several hundred volts (Volt), while the voltage amplitude of each sub RF electric field can be set to a level of several volts (Volt).

[0072] Meanwhile, the method of superimposing the waveform of the main RF electric field and the waveform of each sub-RF electric field through the RF driving unit (200) can be implemented through different circuit combination structures depending on the frequency band of each sub-RF electric field.

[0073] In one embodiment, the RF driver (200) can perform the function of forming the modulated RF electric field by superimposing the main RF electric field with capacitive coupling for the high-frequency band component according to the frequency band of each sub-RF electric field.

[0074] That is, when the RF driving unit (200) superimposes a waveform of a high-frequency sub-RF electric field having a relatively higher frequency band compared to the waveform of the main RF electric field onto the waveform of the main RF electric field, it can control the waveform of the high-frequency sub-RF electric field to be superimposed onto the waveform of the main RF electric field through a capacitive coupling method.

[0075] This waveform superposition method of capacitive coupling facilitates the transmission of high-frequency signals while suppressing the transmission of DC components to multiple RF electrodes (100), thereby allowing perturbations mainly consisting of AC components to be applied to multiple RF electrodes (100).

[0076] In another embodiment, the RF driver (200) can perform the function of forming the modulated RF electric field by superimposing the signal of the control unit (e.g., gate, etc.) of the switching circuit (not shown) that generates the main RF electric field for the low-frequency band component according to the frequency band of each sub-RF electric field.

[0077] That is, when the RF driving unit (200) superimposes the waveform of a low-frequency sub-RF electric field having a low-frequency band onto the waveform of the main RF electric field, a method may be used in which the waveform component of the corresponding low-frequency sub-RF electric field is superimposed onto the signal of the control unit (e.g., a gate, etc.) of the switching circuit (not shown) that generates the waveform of the main RF electric field.

[0078] In this case, the envelope or duty cycle of the waveform of the main RF electric field is modulated in correspondence with the frequency component of the corresponding low-frequency sub-RF electric field, so that at the output terminal, a modulated RF electric field waveform in the form of a combination of the waveform of the main RF electric field and the waveform of the corresponding low-frequency sub-RF electric field can be formed.

[0079] As described above, distinguishing the waveform superposition method according to the frequency band of each sub-RF electric field can be explained as one of the circuit configurations that considers the stability of ion trajectory control using a modulated RF electric field in one embodiment.

[0080] For example, when a waveform of a low-frequency sub-RF electric field having a low-frequency band is superimposed on the waveform of the main RF electric field using a capacitive coupling method, the required capacitance may become excessively large depending on the structure of the RF electrode and the ion migration path, or signal distortion or phase delay may occur.

[0081] Conversely, if the waveform of a high-frequency sub-RF electric field having a high-frequency band is directly superimposed on the control terminal of a switching circuit (not shown) that generates the waveform of the main RF electric field, the stability of the main RF electric field may be reduced due to increased switching loss or increased harmonic components.

[0082] Accordingly, according to one embodiment of the present invention, a high-frequency component is superimposed on the waveform of the main RF electric field through capacitive coupling according to the frequency band of each sub-RF electric field, and a low-frequency component is superimposed through the control terminal of a switching circuit (not shown) that generates the main RF electric field, thereby allowing various forms of modulated RF electric fields to be formed on the ion transport path while alleviating the burden of hardware configuration.

[0083] Meanwhile, it is preferable that each of the above sub-RF electric fields comprises a low-frequency component or a high-frequency component alone and / or in plurality relative to the main RF electric field, and the main RF electric field and / or each of the above sub-RF electric fields may be composed of one or more selected waveforms, for example, a sine wave, a square wave, a triangular wave, and / or any waveform.

[0084] As one embodiment, the frequency of the main RF electric field may be set to a band of several hundred kHz, and each sub RF electric field may be set to include a low-frequency component in a band of several hundred Hz or a high-frequency component in a band of several MHz to several tens of MHz.

[0085] Additionally, the RF driving unit (200) can perform the function of controlling the characteristics of fine perturbation caused by the modulated RF electric field by selectively applying the waveform of each sub-RF electric field in response to the separation characteristics of the target ion.

[0086] At this time, it is preferable that each of the above sub-RF electric fields comprises at least one waveform among, for example, a sine wave, a square wave, a triangular wave, a sawtooth wave, and / or any other waveform.

[0087] Additionally, the RF driving unit (200) can perform the function of controlling the repeated accumulation of fine perturbations by the modulated RF electric field during the residence time when the ion passes between the plurality of RF electrodes (100).

[0088] In addition, the RF driving unit (200) can perform the function of controlling the movement trajectory of ions to be dynamically stabilized through the cumulative application of the micro-perturbation, thereby forming consistent ion separation characteristics despite changes in the external environment.

[0089] Additionally, the RF driving unit (200) can perform the function of operating in a single-phase driving mode, which controls the modulated RF electric field to be applied to a first electrode group among a plurality of RF electrodes (100), and also controls the second electrode group opposite the first electrode group to maintain a preset reference potential (Ground), thereby forming an electric field distribution that changes over time due to the modulated RF electric field between the plurality of RF electrodes (100).

[0090] Specifically, the single-phase driving mode can be implemented by applying the waveform of a modulated RF electric field generated from an RF driver (200), as shown in FIG. 2, to a first group of electrodes (e.g., odd-numbered RF electrodes) among a plurality of RF electrodes (100), and maintaining the second group of electrodes (e.g., even-numbered RF electrodes) opposite thereto at a reference potential.

[0091] The above single-phase driving mode has the advantage of making the circuit configuration relatively simple, but the voltage amplitude applied to the multiple RF electrodes (100) can be relatively large, so there is a possibility that leakage current or discharge phenomena may occur depending on the driving conditions.

[0092] Additionally, the RF driving unit (100) can perform the function of operating in an inverse phase driving mode by generating a pair of modulated RF electric fields having a phase difference of 180 degrees from each other and applying them in inverse phase to adjacent electrode groups among the plurality of RF electrodes (100).

[0093] Through the operation of the above-mentioned reverse phase driving mode, the individual voltage amplitude introduced into the plurality of RF electrodes (100) relative to the external reference potential is reduced, while leakage current according to the impedance characteristics of the device is suppressed, and the trajectory control efficiency of the ions is improved.

[0094] Specifically, the reverse phase driving mode can be implemented as shown in FIG. 3, in which the RF driving unit (200) generates a waveform of a pair of modulated RF electric fields having a phase difference of 180 degrees from each other and applies them to each of the opposing electrode groups (e.g., first and second electrode groups) of the plurality of RF electrodes (100). In this case, the voltage amplitude applied to the plurality of RF electrodes (100) is lowered compared to the single phase driving mode, while a modulated RF electric field of the same strength can be formed between the plurality of RF electrodes (100).

[0095] The above-mentioned reverse phase driving mode can efficiently form a modulated RF electric field formed between a plurality of RF electrodes (100) by applying a waveform of a modulated RF electric field having a phase difference of 180 degrees to each of the RF electrode groups facing each other (e.g., first and second electrode groups).

[0096] In this case, the voltage amplitude applied to the plurality of RF electrodes (100) is lowered compared to the single-phase driving mode, while the electric field strength required by the potential difference between the plurality of RF electrodes (100) can be secured, so electrical stability can be improved even in a structure where the spacing between the plurality of RF electrodes (100) is limited.

[0097] In addition, in the reverse phase driving mode, the voltage amplitude applied to the plurality of RF electrodes (100) is reduced compared to the single phase driving mode, so the magnitude of the leakage current that may be generated by parasitic capacitance between the plurality of RF electrodes (100) and surrounding structures can be relatively reduced. Accordingly, electrical losses under high-frequency driving conditions can be mitigated.

[0098] As described above, the present invention provides a physical ion filter device capable of precisely controlling the dynamic behavior of ions on an ion transport path using a modulated RF electric field.

[0099] The device according to the present invention can expand the degree of freedom for electric field formation compared to the conventional method of applying a DC compensation voltage (CV) to a fixed asymmetric electric field structure by superimposing one or more sub-RF electric fields on a main RF electric field.

[0100] Accordingly, ion selection characteristics can be formed more flexibly, and the device can be configured to enable low-voltage driving, miniaturization, and stable operation against changes in the external environment.

[0101] Furthermore, the present invention allows for various modifications and applications regarding the circuit implementation method, electrode array structure, driving parameter setting and control method, etc., and such modifications may be appropriately changed and implemented within the scope of the technical concept and rights of the present invention.

[0102] Meanwhile, the modulated RF electric field formed inside the plurality of RF electrodes (100) by the aforementioned RF driving unit (200) can induce a resonance-like dynamic response including resonant operation with respect to a specific ion.

[0103] Here, the resonant operation is not a concept limited to mechanical or electrical intrinsic resonance in the strict sense, but may refer to a quasi-resonant stability condition that arises from the interaction between the mobility and mass characteristics of a specific ion and temporally repeated microperturbations formed by a combination of parameters such as frequency, phase, duty ratio, and / or waveform of the main RF electric field and each sub-RF electric field.

[0104] In one embodiment, when the parameter combination of the main RF electric field and each sub-RF electric field reaches a specific condition, the target ion tends to have its lateral kinetic energy periodically canceled out or averaged out under the modulated RF electric field, thereby maintaining a relatively stable trajectory along the central region of the plurality of RF electrodes (100).

[0105] On the other hand, in the case of non-target ions that do not meet the above conditions, as the phase or period mismatch of the micro-perturbation accumulates, the trajectory of movement may gradually diverge, and accordingly, the probability of passing through the filter may decrease.

[0106] Such a quasi-resonant dynamic response can be formed by the cumulative effect of micro-perturbs repeatedly applied during the residence time of the target ion passing between the plurality of RF electrodes (100), and as a result, a physical filtering effect can be realized in which a relatively narrow band pass characteristic is formed for a specific ion.

[0107] A physical ion filter device using a modulated RF electric field according to one embodiment of the present invention described above can operate by selecting passing ions by selectively changing one or more parameters of sub-RF electric fields under main RF electric field conditions, unlike the method of continuously scanning the DC compensation voltage (CV) in a conventional asymmetric electric field-based method.

[0108] In one embodiment, the RF driving unit (200) may change at least one parameter among the frequency, duty cycle, phase, and / or waveform of each sub-RF electric field and, if necessary, adjust the conditions of the main RF electric field simultaneously or in conjunction. In this case, the ion movement behavior formed by the modulated RF electric field after the parameter change can be stabilized to the new conditions within a relatively short time.

[0109] Experimentally, it can be observed that the stabilization time required for the ion trajectory to adapt to the new modulation RF electric field conditions after the above parameter change is within about 10 ms, and subsequently, measuring the ion current signal may require about 10 ms to 100 ms depending on the ion flux and signal stability. Under conditions where the signal-to-noise ratio is sufficiently secured, even when performing measurements continuously while changing the above parameter multiple times, the total measurement time can be maintained within a few seconds.

[0110] Such fast response characteristics can be explained as being due to an operating mechanism in which the ion passage conditions are selectively changed by locally adjusting the fine perturbation conditions of the modulated RF electric field, unlike the process in which the average conditions of the entire ion transport path are reshaped by changing the DC compensation voltage (CV) in conventional asymmetric electric field-based methods.

[0111] Accordingly, when the parameters of each sub-RF electric field are changed, there is no need to reshape the electric field conditions throughout the ion movement path into a new equilibrium state, so the delay time due to condition switching can be relatively reduced.

[0112] In addition, the modulated RF electric field according to the present invention can exhibit operational characteristics that maintain relatively high analysis reproducibility compared to conventional technology with respect to external environmental variables, particularly changes in humidity.

[0113] In conventional mobility-based ion filter devices, changes in atmospheric humidity can cause clustering, where water vapor molecules irreversibly bind around ions. This can alter the effective size and mass of ions, potentially distorting mobility characteristics. Since these effects may lead to changes in the position of measurement peaks or a decrease in resolution, most conventional physical ion filter devices install a gas drying unit upstream to overcome this issue.

[0114] In contrast, in one embodiment according to the present invention, a micro-perturbation superimposed on the main RF electric field is repeatedly applied on the ion movement path, so that the contact time or binding conditions required for ions to bind with water vapor molecules to form a stable cluster can be continuously disturbed.

[0115] Accordingly, it becomes difficult to maintain the bond between ions and water vapor molecules for a long time, and the effect of clustering phenomena caused by changes in humidity can be mitigated. This behavior can be explained as a process in which the movement behavior of ions is formed under dynamic conditions in which the lateral movement state of ions is continuously changed by a modulated RF electric field containing high-frequency components. As a result, the phenomenon in which the movement characteristics of target ions fluctuate excessively despite changes in external humidity can be suppressed.

[0116] Additionally, the RF driving unit (200) may be configured to receive the flow rate of the sample gas from a separate measuring means (not shown) and to control the frequency of the modulated RF electric field or related parameters in conjunction with the change in flow rate. Accordingly, the phenomenon in which the cumulative characteristics of the micro-perturbation experienced by the ion along the path of travel fluctuate excessively due to the change in flow rate may be mitigated.

[0117] Although preferred embodiments of a physical ion filter device using a modulated RF electric field according to the present invention have been described above, the present invention is not limited thereto and can be implemented with various modifications within the scope of the claims, the detailed description of the invention, and the attached drawings, and such modifications are also included in the present invention. Explanation of the symbols

[0118] 100 : Multiple RF electrodes, 200 : RF driver

Claims

Claim 1 In a physical ion filter device that selectively separates ions by being positioned in a path through which ions generated from a sample gas pass, a plurality of RF electrodes that form an electric field in the path of ion movement; A physical ion filter device using a modulated RF electric field, comprising: an RF driver that forms a modulated RF electric field by superimposing one main RF electric field and at least one sub RF electric field, and applies the modulated RF electric field to the plurality of RF electrodes; wherein the RF driver selectively separates target ions by changing the movement behavior or trajectory stability of ions by the modulated RF electric field by controlling parameters of the main RF electric field and each sub RF electric field; wherein the RF driver controls the characteristics of micro-perturbation caused by the modulated RF electric field by selectively applying the waveform of each sub RF electric field in correspondence with the separation characteristics of the target ions, and controls the micro-perturbation caused by the modulated RF electric field to be repeatedly accumulated during the residence time of the ions passing between the plurality of RF electrodes, and controls the movement trajectory of the ions to be dynamically stabilized through the accumulated application of micro-perturbation so that consistent ion separation characteristics are formed despite changes in the external environment. Claim 2 A physical ion filter device using a modulated RF electric field according to claim 1, wherein the RF driving unit controls the characteristics of the modulated RF electric field by individually or in conjunction with at least one parameter among the voltage amplitude, frequency, duty ratio, phase, and waveform of the main RF electric field and each sub-RF electric field. Claim 3 A physical ion filter device using a modulated RF electric field, characterized in that, in claim 2, each sub-RF electric field is set to have a voltage amplitude lower than the voltage amplitude of the main RF electric field, and the RF driver variably controls the separation resolution of ions by a combination of at least one parameter among the voltage amplitude, frequency, duty ratio, phase, and waveform of each sub-RF electric field without increasing the voltage amplitude of the main RF electric field. Claim 4 A physical ion filter device using a modulated RF electric field according to claim 2, wherein each sub-RF electric field includes a low-frequency component or a high-frequency component alone or in plurality relative to the main RF electric field, and the RF driving unit forms the modulated RF electric field by superimposing the high-frequency band component with the main RF electric field through capacitive coupling according to the frequency band of each sub-RF electric field, and forms the modulated RF electric field by superimposing the control terminal signal of a switching circuit that generates the main RF electric field with respect to the low-frequency band component. Claim 5 A physical ion filter device using a modulated RF electric field, wherein, in claim 1 or 4, each sub-RF electric field comprises at least one waveform among a sine wave, a square wave, a triangular wave, a sawtooth wave, and any other waveform, and the RF driving unit controls the characteristics of fine perturbation caused by the modulated RF electric field by selectively applying the waveform of each sub-RF electric field in correspondence with the separation characteristics of the target ion. Claim 6 delete Claim 7 A physical ion filter device using a modulated RF electric field according to claim 1, wherein the RF driving unit operates in a single-phase driving mode, wherein the RF driving unit controls the modulated RF electric field to be applied to a first electrode group among the plurality of RF electrodes and controls the second electrode group opposite the first electrode group to maintain a preset reference potential, thereby forming a time-varying electric field distribution between the plurality of RF electrodes by the modulated RF electric field. Claim 8 A physical ion filter device using a modulated RF electric field according to claim 1, wherein the RF driving unit generates a pair of modulated RF electric fields having a phase difference of 180 degrees from each other and operates in an inverse phase driving mode, applying each to an adjacent group of electrodes among the plurality of RF electrodes in an inverse phase, and wherein, through the inverse phase driving mode, the individual voltage amplitude introduced to the plurality of RF electrodes relative to an external reference potential is reduced, while leakage current according to the impedance characteristics of the device is suppressed, and the trajectory control efficiency of the ions is improved. Claim 9 A physical ion filter device using a modulated RF electric field, characterized in that, in claim 1, the ratio (L / d) of the RF electrode length (L) formed along the ion movement direction to the spacing (d) between the plurality of RF electrodes is configured to have a range of 10 to 50.

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