Flat plate type FAIMS analyzer

Abstract

The invention belongs to the technical field of analytical instruments, and provides a flat plate type FAIMS analyzer, which comprises a separation area, an upper separation electrode, a lower separation electrode, a flat plate type FAIMS, a flat plate type FAIMS and a flat plate type FAIMS, the separation voltage signal source is used for outputting high-frequency asymmetric voltage; the first compensation voltage source is used for outputting negative compensation voltage, and the high-frequency asymmetric voltage and the negative compensation voltage are superposed and then applied to the upper separation electrode; the second compensation voltage source is used for applying the output positive compensation voltage to the lower separation electrode, the absolute value of the positive compensation voltage and the absolute value of the negative compensation voltage at the same moment are equal, and the positive compensation voltage and the negative compensation voltage enable the equal height of the center of the separation area to be kept in a zero potential state. The negative compensation voltage eliminates potential fluctuation caused by the positive compensation voltage in the center of the separation area, so that the center of the separation area is kept in a zero potential state, more target ions reach the detection area through the zero potential state of the center of the separation area, and therefore the FAIMS detection sensitivity is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of analytical instruments, and in particular relates to a flat-plate FAIMS analyzer. Background Art

[0002] High-field asymmetric waveform ion mobility spectrometry (FAIMS) is a gas detection technology that analyzes gas-phase ions at atmospheric pressure. It is based on the nonlinear change of material ion mobility under high electric fields. It separates and identifies ions by applying high-frequency asymmetric electric fields, thereby achieving qualitative and quantitative analysis of different types of ions. FAIMS has the advantages of fast response speed, high selectivity and easy MEMS integration, and has shown great application potential in a variety of fields such as explosive detection, environmental monitoring and medical diagnosis and treatment.

[0003] The flat-plate FAIMS analyzer is a FAIMS analyzer composed of planar electrodes, that is, the separation electrode and the detection electrode in the flat-plate FAIMS analyzer are parallel to the horizontal plane. The separation electrode is located in the separation zone and is divided into an upper separation electrode and a lower separation electrode. When performing gas detection, the gas molecules will first be ionized into ions, and then enter the separation zone to which a high-frequency asymmetric waveform voltage (DV) is applied. The purpose of applying DV is to achieve ion separation by changing the difference in ion mobility under high-field and low-field conditions to produce an offset in the ion trajectory. Under normal circumstances, the frequency of change of DV is much higher than the transmission time scale of ions in the separation zone, so the potential generated by DV at the center of the separation zone can be considered to be zero. However, since the compensation voltage applied to the separation zone changes continuously with time, the potential fluctuation is caused in the central area of ​​the separation zone, which causes the ions to be deflected or lost due to the unstable electric field during transmission, affecting the pass rate of ions in the separation zone, thereby reducing the sensitivity of FAIMS detection.

[0004] Therefore, how to keep the potential in the center of the separation zone at zero so that more ions can reach the detection zone to improve the sensitivity of FAIMS detection is a problem that needs to be solved in the art.

[0005] Public Content

[0006] In order to solve the above problems, the present disclosure provides a flat-plate FAIMS analyzer, which aims to improve the sensitivity of FAIMS detection.

[0007] In order to achieve the above objectives, the present disclosure mainly provides the following technical solutions:

[0008] The present disclosure provides a flat-plate type FAI MS analyzer, comprising:

[0009] a separation zone having an upper separation electrode and a lower separation electrode;

[0010] Separate voltage signal source for outputting high frequency asymmetric voltage;

[0011] A first compensation voltage source, used for outputting a negative compensation voltage, wherein the high-frequency asymmetric voltage and the negative compensation voltage are superimposed and applied to the upper separation electrode;

[0012] The second compensation voltage source is used to apply the output positive compensation voltage to the lower separation electrode, the absolute values ​​of the positive compensation voltage and the negative compensation voltage at the same time are equal, and the positive compensation voltage and the negative compensation voltage make the center of the separation zone maintain a zero potential state at the same height.

[0013] Further, the flat-plate FAI MS analyzer also includes:

[0014] a detection area having an upper bias detection electrode and a lower bias detection electrode;

[0015] a first bias voltage source, used to apply a positive bias voltage to the upper bias detection electrode, so that the upper bias detection electrode detects target negative ions in the sample gas;

[0016] The second bias voltage source is used to apply a negative bias voltage to the lower bias detection electrode, so that the lower bias detection electrode detects target positive ions in the sample gas.

[0017] Furthermore, the absolute values ​​of the positive bias voltage and the negative bias voltage are equal.

[0018] Furthermore, the upper bias detection electrode is electrically connected to a first weak signal detection module, and the lower bias detection electrode is electrically connected to a second weak signal detection module. The first weak signal detection module is used to detect the weak current signal output by the upper bias detection electrode, and the second weak signal detection module is used to detect the weak current signal output by the lower bias detection electrode.

[0019] Furthermore, the first weak signal detection module includes a first operational amplifier and a first feedback resistor, the weak current signal output by the upper bias detection electrode is input into the inverting terminal of the first operational amplifier, the positive bias voltage is input into the non-inverting terminal of the first operational amplifier, one end of the first feedback resistor is connected to the inverting terminal, and the other end is connected to the output terminal of the first operational amplifier.

[0020] Furthermore, the value range of the first feedback resistor is 1 megohm to 1000 gigaohm.

[0021] Furthermore, a shielding electrode is disposed at the periphery of each of the upper bias voltage detection electrode and the lower bias voltage detection electrode, and the shielding electrode is used to construct an electric field shielding region for the detection area.

[0022] Furthermore, the cross section of the shielding electrode is rectangular.

[0023] Furthermore, the shielding electrode, the upper bias voltage detection electrode, and the lower bias voltage detection electrode have the same thickness.

[0024] Furthermore, the flat-plate FAI MS analyzer further comprises: an upper analyzer plate and a lower analyzer plate, and the distance between the upper analyzer plate and the lower analyzer plate ranges from 0.05 mm to 1 mm.

[0025] Compared with the prior art, the present invention has the following advantages:

[0026] The flat-plate FAIMS analyzer disclosed in the present invention includes a separation zone, a separation voltage signal source, a first compensation voltage source, and a second compensation voltage source. The separation zone has an upper separation electrode and a lower separation electrode. The high-frequency asymmetric voltage output by the separation voltage signal source and the negative compensation voltage output by the first compensation voltage source are superimposed and applied to the upper separation electrode. The second compensation voltage source applies the output positive compensation voltage to the lower separation electrode. Since the absolute values ​​of the positive compensation voltage and the negative compensation voltage are equal at the same time, and the signs of the positive compensation voltage and the negative compensation voltage are opposite, the negative compensation voltage eliminates the potential fluctuation caused by the positive compensation voltage in the center of the separation zone, so that the center of the separation zone maintains a zero potential state. The zero potential state in the central area of ​​the separation zone can effectively improve the pass rate of target ions in the separation zone. Since more target ions reach the detection area, the present invention improves the sensitivity of FAI MS detection.

[0027] Other features and advantages of the present disclosure will be described in the following description, and partly become apparent from the description, or be understood by implementing the present disclosure. The purpose and other advantages of the present disclosure can be realized and obtained by the structures pointed out in the description, claims and drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the embodiments of the present disclosure or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present disclosure. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0029] Figure 1 A schematic structural diagram of a flat-plate FAI MS analyzer according to an embodiment of the present disclosure is shown;

[0030] Figure 2a shows a potential distribution diagram of a conventional single bias detection electrode structure;

[0031] Figure 2b shows a potential distribution diagram of a dual bias detection electrode structure according to an embodiment of the present disclosure;

[0032] Figure 3a shows the potential profile of a conventional flat-plate FAI MS analyzer;

[0033] Figure 3b shows a potential distribution diagram of a flat-plate type FAI MS analyzer according to an embodiment of the present disclosure;

[0034] Figure 4 A schematic structural diagram of another flat-plate FAI MS analyzer according to an embodiment of the present disclosure is shown;

[0035] Figure 5a A schematic structural diagram of another flat-plate FAI MS analyzer according to an embodiment of the present disclosure is shown;

[0036] Figure 5b A schematic structural diagram of yet another flat-plate FAI MS analyzer according to an embodiment of the present disclosure is shown. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the embodiments of the present disclosure clearer, the technical solution in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the drawings in the embodiments of the present disclosure. Obviously, the described embodiments are part of the embodiments of the present disclosure, not all of the embodiments. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present disclosure.

[0038] The following is an explanation of the professional terms used in this application:

[0039] DV: refers to the high-frequency asymmetric waveform voltage applied to the separation area, which is output by the separation voltage signal source. The main function of DV is to achieve ion separation by changing the mobility difference of ions under high field and low field conditions, resulting in the deviation of ion trajectories. Different ions respond differently to DV. By adjusting DV, the separation effect can be controlled so that the target ions remain stable in the separation area, while other ions are excluded.

[0040] CV: refers to the compensation voltage applied to the separation area. The compensation voltage is a DC bias voltage output by the compensation voltage source. The main function of CV is to compensate for the difference in mobility of ions under high field and low field conditions, so that the target ions maintain a stable trajectory through the separation area. Different ions have different responses to specific CV values. By adjusting CV, specific ions can be selected and other ions can be excluded. DV is usually used in conjunction with CV to achieve selective separation of ions in complex mixed samples.

[0041] Ion mobility: A physical quantity that describes the drift rate of electrons or ions in a gas under gas phase conditions. It depends on the mass, charge, shape of the ions and the collision characteristics with the medium molecules. In FAIMS, the difference in ion mobility under high and low fields is the core principle for ion separation. It is defined as the ratio of the drift velocity of the ion to the electric field strength.

[0042] The FAIMS analyzer usually includes a separation zone, a detection zone, and a transition zone between the separation zone and the detection zone, wherein a pair of separation electrodes are provided in the separation zone, and a pair of detection electrodes are provided in the detection zone. The flat-plate FAIMS analyzer in the prior art applies DV on one separation plate in the separation zone and CV on the other separation plate. Since CV is constantly changing over time, potential fluctuations will occur in the center of the separation zone, and a single bias voltage is usually applied to the detection zone, so the potential in the center of the detection zone is not zero. Therefore, the electric field in the entire analysis channel (separation zone, transition zone, detection zone) of the existing flat-plate FAIMS analyzer is uneven, which results in some target ions being unable to reach the corresponding detection electrodes, reducing the sensitivity of FAIMS detection.

[0043] Based on this, the present disclosure provides a flat-plate FAIMS analyzer, such as Figure 1 As shown, the analyzer includes: an upper separation electrode 1, a lower separation electrode 2, an ionization source 3, an upper bias detection electrode 4, a lower bias detection electrode 5, a shielding electrode 6, an air inlet area 7, an air outlet area 8, a separation voltage signal source 9, a first compensation voltage source 10, a second compensation voltage source 12, a first bias voltage source 11, a second bias voltage source 13, a lead 14, a plate 15, a first weak signal detection module, and a second weak signal detection module, wherein the first weak signal detection module includes a first operational amplifier 31, a first feedback resistor 32, and a first analog-to-digital converter (ADC) 33. The second weak signal detection module includes a second operational amplifier, a second feedback resistor, and a second ADC (the second operational amplifier, the second feedback resistor, and the second ADC are not shown in the figure).

[0044] The upper separation electrode 1 and the lower separation electrode 2 are located in the separation area, and the upper separation electrode 1 is electrically connected to the separation voltage signal source 9 and to the first compensation voltage source 10. The lower separation electrode 2 is electrically connected to the second compensation voltage source 12. The separation voltage signal source 9 is used to output DV, the first compensation voltage source 10 is used to output negative CV, and the second compensation voltage source 12 is used to output positive CV. The DV output by the separation voltage signal source 9 and the negative CV output by the first compensation voltage source 10 of the present disclosure are applied to the upper separation electrode 1 through a superposition circuit. The positive CV output by the second compensation voltage source 12 is directly applied to the lower separation electrode 2. It should be noted that the absolute values ​​of the positive CV and the negative CV at the same moment are equal, and the signs are opposite, that is, the timing of the positive CV and the negative CV is consistent, that is, the frequency of the positive CV and the negative CV is the same, and the amplitudes of the two are opposite at the same moment.

[0045] The upper bias detection electrode 4 and the lower bias detection electrode 5 are located in the detection area. The upper bias detection electrode 4 and the lower bias detection electrode 5 in the present disclosure can not only be applied with bias voltages respectively, but also can detect ions respectively. That is, the upper bias detection electrode 4 is electrically connected to the first bias voltage source 11 and is electrically connected to the first weak signal detection module; the lower bias detection electrode 5 is electrically connected to the second bias voltage source 13 and is electrically connected to the second weak signal detection module.

[0046] The sample gas in the present disclosure enters the flat-plate FAIMS analyzer from the air inlet area 7. Under the action of the ionization source 3, the molecules in the sample gas are ionized into ions. After the ions enter the separation area, they are separated according to the difference in their mobility under high field and low field under the combined action of DV, positive CV, and negative CV, so that the target ions among all ions enter the transition area, and then are discharged through the air outlet area 8 after being detected in the detection area. The target ions are ions of the substance to be tested in the sample gas except the carrier gas. The target ions include target positive ions and target negative ions. The upper bias detection electrode 4 of the present disclosure detects the target negative ions in the sample gas, and the lower bias detection electrode 5 detects the target positive ions in the sample gas.

[0047] The present disclosure divides CV into two paths, one is the negative CV applied to the upper separation electrode 1 after superimposing with DV, and the other is the positive CV applied to the lower separation electrode 2. Since the amplitudes of the positive CV and the negative CV at the same time are opposite, the center of the separation zone and other high places are kept at a zero potential state. The present disclosure improves the pass rate of target ions in the separation zone and the lateral transmission efficiency of ions through the zero potential state in the center of the separation zone, and also reduces the interference of the edge field of the separation electrode on the transition zone, thereby improving the sensitivity and resolution of FAI MS.

[0048] In the prior art, usually only one bias voltage source is connected to one of the detection electrodes in the detection area, that is, the prior art is a single bias detection electrode structure. The two detection electrodes disclosed in the present invention are respectively connected to a bias voltage source to form a dual bias detection electrode structure in the detection area. That is, the first bias voltage source 11 disclosed in the present invention applies a positive bias voltage PV to the upper bias detection electrode 4, and the second bias voltage source 13 applies a negative PV to the lower bias detection electrode 5, and the positive PV and the negative PV are opposite in positive and negative. Since the positive PV and the negative PV are opposite in positive and negative, the positive PV enables the upper bias detection electrode 4 to capture the target negative ions while the negative PV also enables the lower bias detection electrode 5 to capture the target positive ions. Therefore, the dual bias detection electrode structure disclosed in the present invention achieves the effect of simultaneously detecting positive and negative ions in the sample gas.

[0049] The absolute values ​​of the positive PV and the negative PV in the embodiment of the present disclosure can be equal, that is, the positive PV and the negative PV have the same amplitude and are opposite in positive and negative. When the absolute values ​​of the two are equal, the dual bias detection electrode structure forms a zero potential environment in the center of the detection area. Figure 2a As shown in the potential distribution diagram of the conventional single bias detection electrode structure, the potential distribution in the transition zone is relatively complex, and the central ion has a tendency to move upward under the action of the electric field in the transition zone. However, after the present disclosure adopts the dual bias detection electrode structure, the overall potential distribution is as follows Figure 2b As shown, it significantly improves the ion transmission efficiency in the lateral direction. The dual bias detection electrode structure disclosed in the present invention further ensures the zero potential environment in the center of the detection area through the joint action of positive and negative PV, and realizes the separation of positive and negative ions and efficient detection at the same time.

[0050] The upper bias detection electrode 4 of the present disclosure is electrically connected to the first weak signal detection module, and the lower bias detection electrode 5 is electrically connected to the second weak signal detection module. The first weak signal detection module is used to detect the weak current signal output by the upper bias detection electrode 4, and the second weak signal detection module is used to detect the weak current signal output by the lower bias detection electrode 5. The first weak signal detection module includes a first operational amplifier 31 and a first feedback resistor 32, as well as a first ADC 33. The weak current signal output by the upper bias detection electrode 4 is input to the inverting end of the first operational amplifier 31, and the positive PV is input to the non-inverting end of the first operational amplifier 31. One end of the first feedback resistor 32 is connected to the inverting end, and the other end is connected to the output end of the first operational amplifier 31. The output signal of the first operational amplifier 31 will be transmitted to the first ADC 33 to obtain a corresponding spectrum.

[0051] The first weak signal detection module in the present disclosure converts the weak current signal into a voltage signal and performs transimpedance amplification through a feedback IV conversion method with ultra-high feedback resistance. Since the inverting terminal of the first operational amplifier 31 inputs the weak current signal from the upper bias detection electrode 4, and the in-phase terminal is connected to the positive PV of constant DC, it is equivalent to superimposing the PV while amplifying the weak signal. According to the linear superposition principle of the operational amplifier, the host computer performs digital subtraction on the output signal to filter out the DC bias part and only retain the detection result of the weak signal. The present disclosure realizes high-sensitivity weak signal extraction and measurement by superimposing and filtering PV.

[0052] The value range of the first feedback resistor 32 and the second feedback resistor in the present disclosure is 1 megohm to 1000 gigaohm. The value can be selected according to the actual scenario. In addition, the second weak signal detection module has the same structure as the first weak signal detection module and will not be repeated here.

[0053] The detection area of ​​the present invention is also provided with a shielding electrode 6, and a shielding electrode 6 is respectively provided on the periphery of the upper bias detection electrode 4 and the lower bias detection electrode 5. The shielding electrode 6 can be a square ring structure, and the four side walls of the shielding electrode 6 surround the corresponding bias detection electrode. The cross section of the shielding electrode 6 is rectangular, and its main function is to construct an electric field shielding area for the detection area, so as to effectively isolate the influence of external electromagnetic interference on the detection signal, reduce the introduction of noise, and thus improve the stability and accuracy of signal detection. At the same time, the shielding electrode 6 also effectively reduces the interference of the edge field on the ion migration trajectory, thereby also improving the separation accuracy. The thickness of the shielding electrode 6, the upper bias detection electrode 4, and the lower bias detection electrode 5 of the present invention is the same, so that the target positive ions and the target negative ions can smoothly enter the detection area.

[0054] The present disclosure forms a stable zero potential environment in the separation zone, transition zone and detection zone by applying DV and negative CV to the upper separation electrode 1, applying positive CV to the lower separation electrode 2, applying positive PV to the upper detection electrode, applying negative PV to the lower detection electrode, and arranging a shielding electrode 6 in the detection zone. Figure 3a It is an electric field distribution diagram of a conventional flat-plate FAIMS analyzer in the prior art. In a conventional flat-plate FAIMS analyzer, only DV is applied to the upward separation electrode 1 and CV is applied to the downward separation electrode 2. The detection area is a single bias structure, and no shielding electrode 6 is set in the detection area. Figure 3b This is the electric field distribution diagram of the flat-plate central zero-potential FAIMS analyzer disclosed in the present invention. It can be seen that the electric field distribution of the new central zero-potential FAIMS analyzer proposed in the present invention is better than that of the conventional analyzer, and can effectively avoid ion loss and signal noise caused by uneven electric field.

[0055] The lead 14 disclosed in the present invention can be connected to the internal electrode of the analyzer through a printed circuit board (PCB) via or through-glass via (TGV) technology. The analyzer plate 15 can be a PCB substrate or a glass substrate. The distance between the upper analyzer plate and the lower analyzer plate can be 0.05-1mm, and the preferred spacing can be 0.5mm.

[0056] like Figure 4 As shown, another structural schematic diagram of the flat-plate FAIMS analyzer provided by the present disclosure, the upper analyzer plate of the flat-plate FAIMS analyzer of the present disclosure is provided with an ion source and analyzer connection 18, a lead through hole 19, the lead through hole 19 is connected to the center position of the upper bias detection electrode 4, and the two ends of the lower analyzer plate are respectively provided with an air inlet 16 and an air outlet 17. The central axis of the connection 18 between the ion source and the analyzer coincides with the central axis of the air inlet 16. The sample gas enters from the air inlet 16 and reaches the air inlet area 7, and the molecules in the sample gas are ionized by the ion source 3 through the connection 18 between the ion source and the analyzer to obtain ions, which are finally discharged from the air outlet 17.

[0057] like Figure 5a and Figure 5b As shown, the flat-plate FAIMS analyzer provided by the present disclosure is Figure 1 and Figure 4 In addition to the components shown in the figure, it also includes an analyzer fixture 26, an intermediate plate 27, an air inlet copper column 29, an air outlet copper column 28, and a first weak signal detection module and a main control board connection wiring port 30. Among them, the first weak signal detection module and the main control board connection wiring port 30 are arranged on the side wall of the analyzer fixture 26. The material of the analyzer fixture 26 can be aluminum alloy or stainless steel, and the processing method can be a CNC lathe or metal 3D printing technology. The intermediate plate 27 and the upper and lower analyzer plates together form an analysis channel, and the analysis channel is the airflow channel. The ionization source 3 is a vacuum ultraviolet lamp ion source. The outer diameter of the air inlet copper column 29 matches the inner diameter of the air inlet 16, and the outer diameter of the air outlet copper column 28 matches the inner diameter of the air outlet 17.

[0058] The sample gas of the present disclosure enters the flat-plate FAIMS analyzer through the inlet copper column 29, and the molecules in the sample gas are ionized into positive and negative ions under the action of the vacuum ultraviolet lamp ion source 3. The positive and negative ions are separated and screened under the joint action of DV and positive and negative CV, and finally the target positive ions reach the lower bias detection electrode 5 and are detected, while the target negative ions are detected by the upper bias detection electrode 4.

[0059] In the present disclosure, the ion source 3 may also be a corona discharge ion source, a photoelectric effect ion source or a radiation source.

[0060] The present invention effectively stabilizes the zero potential environment of the separation zone, transition zone and detection zone by applying positive and negative CV and DV to the separation electrode and adopting a dual bias detection electrode structure in the detection zone. The interference to the central potential during the CV scanning process is reduced, thereby improving the lateral transmission efficiency of ions. In addition, positive and negative PVs with equal absolute values ​​are applied to the upper and lower detection electrodes in the detection zone, respectively, forming a more uniform electric field distribution, ensuring the transmission stability of ions in the transition zone and the detection zone, further optimizing the ion transmission path and improving the overall transmission efficiency.

[0061] The present invention introduces a central zero potential environment in the separation zone and the detection zone to achieve efficient and synchronous separation of positive and negative ions in the same separation electric field. In the detection zone, a dual bias detection electrode structure is adopted to apply positive and negative PVs through the upper and lower electrodes to guide the target positive and negative ions to the detection zone respectively, thereby achieving simultaneous detection of positive and negative ions.

[0062] In addition, the voltage design of the present invention is combined with the flat-plate structure to achieve high-resolution and high-sensitivity detection through voltage distribution optimization, avoiding complex structural design, significantly improving the miniaturization and integration capabilities of the FAIMS analyzer, and being more suitable for portable and multi-scenario application requirements.

[0063] Although the present disclosure has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present disclosure.

Claims

1. A flat-plate FAIMS analyzer, characterized in that: include: a separation zone having an upper separation electrode and a lower separation electrode; Separate voltage signal source for outputting high frequency asymmetric voltage; A first compensation voltage source, used for outputting a negative compensation voltage, wherein the high-frequency asymmetric voltage and the negative compensation voltage are superimposed and applied to the upper separation electrode; The second compensation voltage source is used to apply the output positive compensation voltage to the lower separation electrode, the absolute values ​​of the positive compensation voltage and the negative compensation voltage at the same time are equal, and the positive compensation voltage and the negative compensation voltage make the center of the separation zone maintain a zero potential state at the same height.

2. The flat-panel FAIMS analyzer according to claim 1, characterized in that: Also includes: a detection area having an upper bias detection electrode and a lower bias detection electrode; a first bias voltage source, used to apply a positive bias voltage to the upper bias detection electrode, so that the upper bias detection electrode detects target negative ions in the sample gas; The second bias voltage source is used to apply a negative bias voltage to the lower bias detection electrode, so that the lower bias detection electrode detects target positive ions in the sample gas.

3. The flat-panel FAIMS analyzer according to claim 2, characterized in that: The absolute values ​​of the positive bias voltage and the negative bias voltage are equal.

4. The flat-panel FAIMS analyzer according to claim 2, characterized in that: The upper bias detection electrode is electrically connected to a first weak signal detection module, and the lower bias detection electrode is electrically connected to a second weak signal detection module. The first weak signal detection module is used to detect the weak current signal output by the upper bias detection electrode, and the second weak signal detection module is used to detect the weak current signal output by the lower bias detection electrode.

5. The flat-panel FAIMS analyzer according to claim 4, characterized in that: The first weak signal detection module includes a first operational amplifier and a first feedback resistor. The weak current signal output by the upper bias detection electrode is input into the inverting terminal of the first operational amplifier, the positive bias voltage is input into the non-inverting terminal of the first operational amplifier, one end of the first feedback resistor is connected to the inverting terminal, and the other end is connected to the output terminal of the first operational amplifier.

6. The flat-panel FAIMS analyzer according to claim 5, characterized in that: The value range of the first feedback resistor is 1 megohm to 1000 gigaohm.

7. The flat-panel FAIMS analyzer according to claim 2, characterized in that: A shielding electrode is disposed on the periphery of the upper bias voltage detection electrode and the lower bias voltage detection electrode, respectively, and the shielding electrode is used to construct an electric field shielding region for the detection area.

8. The flat-panel FAIMS analyzer according to claim 7, characterized in that: The cross section of the shielding electrode is rectangular.

9. The flat-panel FAIMS analyzer according to claim 7, characterized in that: The shielding electrode, the upper bias voltage detection electrode, and the lower bias voltage detection electrode have the same thickness.

10. The flat-plate FAIMS analyzer according to any one of claims 1 to 9, characterized in that: Also includes: The upper analyzer plate and the lower analyzer plate, the distance between the upper analyzer plate and the lower analyzer plate ranges from 0.05 mm to 1 mm.

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