Device for screening positive and negative micro-droplets by external electric field and on-line analysis and use method thereof

Abstract

The invention relates to the technical field of micro-droplet analysis, in particular to a positive and negative micro-droplet screening and online analysis device with an external electric field, comprising: a pneumatic atomization generation module comprising an aerosol generator and a carrier gas pressure regulation assembly; the electric field screening module comprises a deflection tube and an ultra-low noise high-voltage generator, and the deflection tube is embedded into a conducting layer in the inner side area of the tube wall to form an asymmetric electric field area; a sample inlet of the mass spectrum detection module is connected with the tail end of the deflection tube. By arranging the deflection tube and the asymmetric electric field, efficient screening of positive / negative electric micro-droplets is achieved, differential deflection tracks of the micro-droplets in a non-uniform field are utilized, micro-droplets with opposite electric properties are directly removed, and multi-stage separation operation steps are simplified; the three modules are integrally connected in series, so that the whole-course closed transmission of the micro-droplets from generation, screening to analysis is realized, the micro-droplets are ensured to enter the mass spectrum without loss, and the problems of sample adsorption and volatilization loss caused by traditional offline separation are solved.

Description

Technical Field

[0001] The present invention relates to the technical field of micro-droplet analysis, and in particular to an external electric field for screening positive and negative micro-droplets, an on-line analysis device and a method for using the same. Background Art

[0002] Due to their unique physical and chemical properties (such as high specific surface area, interfacial effect, and charge enrichment ability), micro-droplets have become a frontier field in the research of gas-liquid interface reactions in recent years. During the generation of micro-droplets such as ultrasonic atomization, electrospray, or pneumatic atomization, due to charge separation, the droplets generally carry a net positive or negative charge. This electrical property not only affects the stability, mass transfer efficiency, and motion behavior of micro-droplets, but may also significantly change the chemical reaction path and kinetic process through mechanisms such as electrostatic interaction and electric field-induced polarization.

[0003] However, current research is mostly based on the experimental results of mixed-electrical micro-droplets, making it difficult to distinguish the differential contributions of positive and negative electrical droplets to chemical reactions. The formation mechanism of the electrical properties of micro-droplets is affected by the coupling of multiple factors such as atomization method, solution properties, particle size and distribution, resulting in significant bottlenecks in the quantitative control of the charge amount and the analysis of the electrical property-reaction correlation law. Traditional electrical separation devices mostly adopt a straight-tube uniform electric field design. The residence time of droplets in the electric field is short, and the deflection trajectory is easily disturbed, resulting in insufficient screening purity and inability to adapt to the charge-mass ratio differences of different particle size droplets. To improve the screening effect, researchers often need to connect multiple separation modules in series. However, multi-stage operation will exacerbate droplet volatilization and adsorption loss, and the process of transferring to mass spectrometry analysis after offline collection further introduces contamination risks, making it difficult to achieve in-situ detection. Summary of the Invention

[0004] To solve the above problems, the present application provides an external electric field for screening positive and negative micro-droplets and an on-line analysis device, including: a pneumatic atomization generation module, including an aerosol generator and a carrier gas pressure adjustment component, for generating micro-droplets with controllable sizes; an electric field screening module, including a deflection tube and an ultra-low noise high voltage generator, the deflection tube is embedded with a conductive layer in the inner wall area to form an asymmetric electric field area, and a screening electric field is formed by applying a positive or negative high voltage to remove micro-droplets with an electric property opposite to that of the screening electric field; a mass spectrometry detection module, whose inlet is close to the end of the deflection tube, for real-time detection of the chemical composition of single-electrical micro-droplets after screening.

[0005] In one embodiment, the deflection tube is a three-dimensional spiral structure, the conductive layer and the insulating layer are alternately distributed, the conductive layer is independently controlled in sections along the spiral axis direction, and a laminar gas sheath flow is introduced into the spiral channel, so that the micro-droplets are arranged in a single layer under the action of inertial focusing and then enter the deflection tube.

[0006] In one embodiment, the conductive layer of the three-dimensional spiral deflection tube is prepared by a flexible circuit board process, and the ratio of the width to the interval of the conductive layer is 1:2 to 1:5, and the ratio of the radius of curvature of the spiral channel to the diameter of the micro-droplet is 100:1 to 500:1.

[0007] In one embodiment, multiple conductive layers in the deflection tube are connected to a programmable high-voltage power supply to form a gradient electric field that gradually increases along the direction of droplet movement.

[0008] A method for using an external electric field to screen positive and negative micro-droplets and an on-line analysis device includes the following steps:

[0009] S1. Micro-droplet generation and size regulation:

[0010] Adjust the carrier gas pressure of the pneumatic atomization generation module so that the sample solution generates micro-droplets of different sizes through the aerosol generator;

[0011] S2. Establishment of the electrical screening field and polarity selection:

[0012] Start the ultra-low noise high-voltage generator, apply a positive or negative high voltage to the conductive layer embedded in the deflection tube, and form an asymmetric electric field region in the deflection tube;

[0013] S3. Electrical screening of micro-droplets:

[0014] Make the micro-droplets generated in step S1 flow through the asymmetric electric field region of the deflection tube, where: when a positive high voltage is applied, the positively charged micro-droplets are repelled by the electric field and pass through the deflection tube, and the negatively charged micro-droplets are deflected to the tube wall and removed by adhesion; when a negative high voltage is applied, the negatively charged micro-droplets pass through the deflection tube, and the positively charged micro-droplets are deflected and removed;

[0015] S4. Real-time on-line mass spectrometry detection:

[0016] Direct the single-electrical property micro-droplets after screening into the mass spectrometry detection module. The mass spectrometry operates in a positive or negative mode, collects mass spectrometry signals and correlates the electrical property parameters of the micro-droplets to achieve synchronous acquisition of chemical composition and electrical property data.

[0017] In one embodiment, the outlet of the pneumatic atomization generation module is connected to the inlet of the deflection tube of the electric field screening module.

[0018] In one embodiment, the ultra-low noise high-voltage generator is connected to the conductive layer embedded in the deflection tube through a wire.

[0019] The beneficial effects of the present invention are as follows:

[0020] An external electric field screening positive and negative microdroplets and on-line analysis device of the present application includes: a pneumatic atomization generation module, an electric field screening module, and a mass spectrometry detection module. When the device is running, the pneumatic atomization generation module starts to work, converts the sample solution into microdroplets with controllable sizes, and the generated microdroplets enter the electric field screening module. Under the action of an ultra-low noise high-voltage generator, an asymmetric electric field region is formed through a conductive layer embedded in the inner region of the tube wall of the deflection tube. When a positive high voltage is applied, the positively charged microdroplets will be repelled and pass through the deflection tube, while the negatively charged microdroplets will be deflected and removed; when a negative high voltage is applied, the negatively charged microdroplets will be repelled and pass through the deflection tube, and the positively charged microdroplets will be deflected and removed, thereby realizing the screening of the electrical properties of microdroplets and obtaining microdroplets with a single electrical property. The single-electrical-property microdroplets after screening directly enter the mass spectrometry detection module to perform real-time detection of the chemical composition of these microdroplets. By setting the deflection tube and the asymmetric electric field, the efficient screening of positive / negative electrical property microdroplets is realized. By using the differential deflection trajectories of microdroplets in the non-uniform field, the microdroplets with opposite electrical properties are directly removed, simplifying the multi-stage separation operation steps; by setting the pneumatic atomization generation module, the electric field screening module, and the mass spectrometry detection module, the integrated series connection of the three modules realizes the whole-process closed transmission of microdroplets from generation, screening to analysis, ensuring that the microdroplets enter the mass spectrometry without loss, solving the problems of sample adsorption and volatilization loss caused by traditional off-line separation, and providing a hardware basis for the real-time monitoring of the chemical reaction process. By setting the ultra-low noise high-voltage generator, the flexible screening of positively charged or negatively charged microdroplets by a single device is realized. Only by switching the electrical property of the high voltage can the direction of the electric field be controlled reversely without modifying the hardware structure, significantly improving the adaptability of the device to different research needs. Description of the Drawings

[0021] Figure 1 It is a schematic structural diagram of this patent;

[0022] Symbol description in the figure:

[0023] 1. Pneumatic atomization generation module;

[0024] 2. Electric field screening module; 21. Deflection tube; 22. Ultra-low noise high-voltage generator; 23. Conductive layer; 24. Insulating layer;

[0025] 3. Mass spectrometry detection module. Detailed Embodiments

[0026] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present application clearer, the present application will be further described in detail below with reference to the drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0027] It should be noted that the terms "first" and "second" are only used for descriptive purposes and should not be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of such features. In the description of this application, "a plurality of" means two or more, unless otherwise specifically defined.

[0028] As Figure 1 shown, an external electric field screening positive and negative micro-droplets and on-line analysis device includes:

[0029] A pneumatic atomization generation module 1, which includes an aerosol generator and a carrier gas pressure regulating component, is used to generate micro-droplets with controllable sizes;

[0030] An electric field screening module 2, which includes a deflection tube 21 and an ultra-low noise high voltage generator 22. A conductive layer 23 is embedded in the inner wall area of the deflection tube 21 to form an asymmetric electric field region. By applying a positive or negative high voltage, a screening electric field is formed to remove micro-droplets with an electric property opposite to that of the screening electric field;

[0031] A mass spectrometry detection module 3, whose sampling port is close to the end of the deflection tube 21, is used to detect the chemical composition of single-electricity micro-droplets after screening in real time.

[0032] Specifically, the outlet of the pneumatic atomization generation module 1 is connected to the inlet of the deflection tube 21 of the electric field screening module 2, and the sealed interface ensures the stable transmission of micro-droplets; the end of the deflection tube 21 of the electric field screening module 2 is close to the inlet of the mass spectrometry detection module 3 to ensure that the screened micro-droplets directly enter the mass spectrometry analysis. The ultra-low noise high-voltage generator 22 is connected to the conductive layer 23 embedded in the deflection tube 21 through a wire, and the direction of the electric field is controlled by applying positive / negative high voltage. When the device is operating, first, the pneumatic atomization generation module 1 starts to work. Under the action of the carrier gas pressure regulating component, the aerosol generator converts the sample solution into micro-droplets with controllable sizes according to the set carrier gas pressure. Different carrier gas pressures will result in different sizes of the generated micro-droplets. The generated micro-droplets enter the electric field screening module 2. Under the action of the ultra-low noise high-voltage generator 22, the deflection tube 21 forms an asymmetric electric field region through the conductive layer 23 embedded in the inner wall area. When a positive high voltage is applied, the positively charged micro-droplets will be repelled and pass through the deflection tube, while the negatively charged micro-droplets will be deflected and removed; when a negative high voltage is applied, the negatively charged micro-droplets will be repelled and pass through the deflection tube, and the positively charged micro-droplets will be deflected and removed, thereby realizing the screening of the electric properties of micro-droplets and obtaining micro-droplets with a single electric property. The screened micro-droplets with a single electric property directly enter the mass spectrometry detection module 3. The inlet of the mass spectrometry detection module 3 is close to the end of the deflection tube 21 to perform real-time detection of the chemical composition of these micro-droplets. In this application, by setting the deflection tube 21 and the asymmetric electric field, the efficient screening of positively / negatively charged micro-droplets is realized. By utilizing the differential deflection trajectories of the droplets in the non-uniform field, the anti-polarity droplets are directly removed, simplifying the multi-stage separation operation steps; by setting the pneumatic atomization generation module 1, the electric field screening module 2, and the mass spectrometry detection module 3, the integrated series connection of the three modules realizes the whole-process closed transmission of micro-droplets from generation, screening to analysis, ensuring that the micro-droplets enter the mass spectrometry without loss, solving the problems of sample adsorption and volatilization loss caused by traditional offline separation, and providing a hardware basis for the real-time monitoring of chemical reaction processes. By setting the ultra-low noise high-voltage generator 22, the flexible screening of positively charged or negatively charged micro-droplets by a single device is realized. Only by switching the voltage electric property can the direction of the electric field be controlled reversely without modifying the hardware structure, significantly improving the adaptability of the device to different research requirements.

[0033] As Figure 1 shown, the deflection tube 21 is a three-dimensional spiral structure, with the conductive layer 23 and the insulating layer 24 alternatingly distributed. The conductive layer 23 is independently controlled in sections along the spiral axis direction. A laminar gas sheath flow is introduced into the spiral channel, so that the micro-droplets gather and arrange and then enter the deflection tube 21.

[0034] Specifically, under the combined action of centrifugal force and sheath gas flow driving force, the micro-droplets migrate towards the outer side of the tube wall along the spiral axis in the spiral channel, forming a stable spiral motion trajectory. The spiral structure extends the movement path of the droplets in the electric field region (increasing the residence time by 3 - 5 times compared to a straight tube), ensuring sufficient electric field action. The conductive layer 23 forms local strong electric field regions (conductive layer regions) and weak / no electric field regions (insulating layer regions) in the spiral channel through segmented independent control. When the droplets pass through the conductive layer 23, they are accelerated and deflected by the electric field force, and maintain their trajectories due to inertia when entering the insulating layer 24, forming an alternating action mode of "pulsed deflection - inertial slip". The sheath gas (flow rate 1 - 5 m / s) forms a stable laminar boundary layer in the spiral channel, forcing the droplets to aggregate; at the same time, the inertial focusing effect induced by the spiral curvature makes the droplets arrange in a single radial position in a single layer, eliminating the randomness of spatial distribution and ensuring the uniformity of subsequent electric field screening. The segmented conductive layer 23 distributed along the spiral axis is controlled by a programmed voltage, enabling the droplets to undergo multi-stage screening during the spiral motion: large charge droplets are quickly separated in the high electric field section, and residual interfering components are refined and removed in the low electric field section. The spiral channel extends the movement path of the droplets, combined with the spatio-temporal voltage regulation of the segmented electrodes, enabling the droplets to sequentially pass through the screening regions with different electric field strengths. Compared with single-stage screening in a straight tube, multi-stage spiral screening can increase the purity of the target droplets from 70% to over 95%.

[0035] As Figure 1 shown, the conductive layer 23 of the three-dimensional spiral deflection tube 21 is prepared by a flexible circuit board process, and the width-to-spacing ratio of the conductive layer 23 is 1:2 to 1:5, and the ratio of the curvature radius of the spiral channel to the diameter of the micro-droplets is 100:1 to 500:1.

[0036] Specifically, the conductive layer 23 is prepared on the inner wall of the spiral channel by a flexible circuit board process, with a width-to-spacing ratio (1:2 to 1:5). The width of the conductive layer 23 determines the electric field coverage range, and the spaced insulating regions block electric field interference, forming a periodic "strong electric field - weak electric field" alternating distribution, forcing the droplets to repeatedly experience pulsed deflection of electric field acceleration and inertial slip during the spiral motion. The ratio of the curvature radius (R) of the spiral channel to the diameter (d) of the micro-droplets (R / d = 100:1 to 500:1) is determined by hydrodynamic simulation.

[0037] As Figure 1 shown, multiple segments of the conductive layer 23 in the deflection tube 21 are connected to a programmable high-voltage power supply, forming a gradient electric field that gradually increases along the droplet movement direction.

[0038] Specifically, the electric field intensity of the initial segment is set in a lower range, which can enable the micro-droplets to be subjected to a relatively small electric field force when entering the electric field region, avoiding the fragmentation, deformation or irregular movement of the micro-droplets due to excessive electric field force in the initial stage, ensuring the integrity of the micro-droplets and the stability of the movement, and being conducive to the subsequent screening process. The electric field intensity of the final segment is increased to a higher range, which can generate a stronger electric field force on the micro-droplets, making the movement trajectories of micro-droplets with different electricities more obvious in the electric field, thereby improving the screening accuracy and efficiency, and being able to more effectively separate the micro-droplets with the target electricity. The setting of the gradient electric field can adapt to micro-droplets of different sizes, charge distributions and movement speeds. By gradually increasing the electric field intensity, appropriate actions can be taken on the micro-droplets at different stages, improving the adaptability of the device to different micro-droplet samples.

[0039] As Figure 1 shown, a microfluidic feedback system is also provided. The microfluidic feedback system includes: a high-speed camera, arranged at the outlet of the deflection tube 21, for real-time monitoring of the micro-droplet distribution state; a PID controller, for dynamically adjusting the voltages of each segment of the electrodes according to the sensor signals.

[0040] Specifically, the micro-droplets screened by the electric field screening module 2 flow out from the deflection tube 21. At this time, the high-speed camera arranged at the outlet of the deflection tube 21 starts to work. The high-speed camera uses image recognition technology to perform real-time monitoring and analysis on the distribution state information such as the position, quantity, movement trajectory, etc. of the micro-droplets by quickly taking the movement images of the micro-droplets. The high-speed camera converts the monitored micro-droplet distribution state information into electrical signals (sensor signals) and transmits them to the PID controller. The PID controller dynamically adjusts the voltages of each segment of the electrodes in the deflection tube 21 in the electric field screening module 2 according to the calculated deviation according to the proportional, integral and differential control algorithms. By real-time monitoring the micro-droplet distribution state and timely adjusting the electric field, the microfluidic feedback system can accurately control the movement trajectory of the micro-droplets, ensuring that only the micro-droplets with the target electricity can accurately enter the mass spectrometry detection module 3, greatly improving the accuracy of the electric field screening module 2 for screening the electricity of the micro-droplets, reducing the situations of false screening and missed screening, and making the detection results more accurate and reliable.

[0041] As Figure 1 shown, a method for using an external electric field screening positive and negative micro-droplets and an on-line analysis device includes the following steps:

[0042] S1. Micro-droplet generation and size regulation:

[0043] Adjust the carrier gas pressure of the pneumatic atomization generation module 1 to generate micro-droplets from the sample solution through the aerosol generator;

[0044] S2. Establishment of the electric screening field and polarity selection:

[0045] Start the ultra-low noise high-voltage generator 22, apply a positive or negative high voltage to the embedded conductive layer 23 in the deflection tube 21, and form an asymmetric electric field region in the deflection tube 21;

[0046] S3. Micro-droplet electrical property screening:

[0047] Make the micro-droplets generated in step S1 flow through the asymmetric electric field region of the deflection tube 21. Among them: when a positive high voltage is applied, the positively charged micro-droplets are repelled by the electric field and pass through the deflection tube 21, and the negatively charged micro-droplets are deflected to the tube wall and removed by attachment; when a negative high voltage is applied, the negatively charged micro-droplets pass through the deflection tube 21, and the positively charged micro-droplets are deflected and removed;

[0048] S4. Real-time online mass spectrometry detection:

[0049] Directly introduce the single-electrical-property micro-droplets after screening into the mass spectrometry detection module 3. The mass spectrometry operates in a positive or negative mode, collects mass spectrometry signals and correlates with the electrical property parameters of the micro-droplets, and realizes the synchronous acquisition of chemical composition and electrical property data.

[0050] The beneficial effects of this application compared with the prior art:

[0051] An external electric field screening positive and negative microdroplets and on-line analysis device of the present application includes: a pneumatic atomization generation module 1, which includes an aerosol generator and a carrier gas pressure regulating component, and is used to generate microdroplets with controllable sizes; an electric field screening module 2, which includes a deflection tube 21 and an ultra-low noise high-voltage generator 22. A conductive layer 23 is embedded in the inner wall area of the deflection tube 21 to form an asymmetric electric field area. By applying a positive or negative high voltage, a screening electric field is formed to remove microdroplets with polarities opposite to that of the screening electric field; a mass spectrometry detection module 3, whose sampling port is connected to the end of the deflection tube 21, and is used to detect the chemical composition of the single-electronic microdroplets after screening in real time. When the device is running, the pneumatic atomization generation module 1 starts to work. Under the action of the carrier gas pressure regulating component, the aerosol generator converts the sample solution into microdroplets with controllable sizes according to the set carrier gas pressure. The generated microdroplets enter the electric field screening module 2. Under the action of the ultra-low noise high-voltage generator 22, the deflection tube 21 forms an asymmetric electric field area through the conductive layer 23 embedded in the inner wall area. When a positive high voltage is applied, the positively charged microdroplets will be repelled and pass through the deflection tube, while the negatively charged microdroplets will be deflected and removed; when a negative high voltage is applied, the negatively charged microdroplets will be repelled and pass through the deflection tube, and the positively charged microdroplets will be deflected and removed, so as to realize the screening of the electric properties of microdroplets and obtain single-electronic microdroplets. The single-electronic microdroplets after screening directly enter the mass spectrometry detection module 3. The sampling port of the mass spectrometry detection module 3 is close to the end of the deflection tube 21, and the chemical composition of these microdroplets is detected in real time. By setting the deflection tube 21 and the asymmetric electric field, the efficient screening of positive / negative electric microdroplets is realized. By using the differential deflection trajectories of droplets in the non-uniform field, the anti-polarity droplets are directly removed, simplifying the multi-stage separation operation steps; by setting the pneumatic atomization generation module 1, the electric field screening module 2, and the mass spectrometry detection module 3, the integrated series connection of the three modules realizes the whole-process closed transmission of microdroplets from generation, screening to analysis, ensuring that the microdroplets enter the mass spectrometry without loss, solving the problems of sample adsorption and volatilization loss caused by traditional off-line separation, and providing a hardware basis for the real-time monitoring of the chemical reaction process. By setting the ultra-low noise high-voltage generator 22, the flexible screening of positive or negative electric microdroplets by a single device is realized. Only by switching the voltage polarity can the electric field direction be reversely controlled without modifying the hardware structure, significantly improving the adaptability of the device to different research requirements.

[0052] Although the embodiments of the present invention have been shown and described, for those of ordinary skill in the art, it can be understood that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principle and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

[0053] In the description of the present invention, it should be noted that, unless otherwise clearly defined and limited, the terms "installed", "connected", and "coupled" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection; it can also be directly connected, or indirectly connected through an intermediate medium, and can be the communication inside two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific situations.

Claims

1. An external electric field screening positive and negative micro-droplets and on-line analysis device, characterized in that Comprising: A pneumatic atomization generation module (1), including an aerosol generator and a carrier gas pressure regulating component, for generating micro-droplets with controllable sizes; An electric field screening module (2), including a deflection tube (21) and an ultra-low noise high voltage generator (22), wherein a conductive layer (23) is embedded in the inner wall area of the deflection tube (21) to form an asymmetric electric field region, and a screening electric field is formed by applying a positive or negative high voltage, for removing micro-droplets with an electric property opposite to that of the screening electric field; A mass spectrometry detection module (3), whose inlet is close to the end of the deflection tube (21), for real-time detecting the chemical composition of the single-electricity micro-droplets after screening.

2. The on-line analysis device for screening positive and negative micro-droplets by applying an external electric field according to claim 1, characterized in that The deflection tube (21) is of a three-dimensional spiral structure, the conductive layer (23) and the insulating layer (24) are alternately distributed, the conductive layer (23) is independently controlled in sections along the spiral axis direction, and a laminar gas sheath flow is introduced into the spiral channel, so that the micro-droplets are arranged in a single layer under the action of inertial focusing and then enter the deflection tube (21).

3. An external electric field screening positive and negative micro-droplets and on-line analysis device according to claim 2, characterized in that, The conductive layer (23) of the three-dimensional spiral deflection tube (21) is prepared by a flexible circuit board process, the ratio of the width to the interval of the conductive layer (23) is 1:2 to 1:5, and the ratio of the curvature radius of the spiral channel to the micro-droplet diameter is 100:1 to 500:

1.

4. An external electric field screening positive and negative micro-droplets and on-line analysis device according to claim 1, characterized in that, The multi-section conductive layers (23) in the deflection tube (21) are connected to a programmable high voltage power supply to form a gradient electric field gradually increasing along the moving direction of the micro-droplets.

5. An external electric field screening positive and negative micro-droplets and on-line analysis device according to claim 4, characterized in that A microfluidic feedback system is further provided, and the microfluidic feedback system includes: a high-speed camera, arranged at the outlet of the deflection tube (21), for real-time monitoring the distribution state of the micro-droplets; a PID controller, for dynamically adjusting the electrode voltages of each section according to the sensor signals.

6. A method for screening positive and negative micro-droplets by an applied electric field and the use method of an on-line analysis device, characterized in that, Including the following steps: S1. Generation and size regulation of micro-droplets: Adjust the carrier gas pressure of the pneumatic atomization generation module (1) to generate micro-droplets of different sizes from the sample solution through the aerosol generator; S2. Establishment of an electric property screening field and polarity selection: Start the ultra-low noise high voltage generator (22), and apply a positive or negative high voltage to the conductive layer (23) embedded in the deflection tube (21) to form an asymmetric electric field region in the deflection tube (21); S3. Electric property screening of micro-droplets: Let the micro-droplets generated in step S1 flow through the asymmetric electric field region of the deflection tube (21), wherein: when a positive high voltage is applied, the positively charged micro-droplets are repelled by the electric field and pass through the deflection tube (21), and the negatively charged micro-droplets are deflected to the tube wall and removed; when a negative high voltage is applied, the negatively charged micro-droplets pass through the deflection tube (21), and the positively charged micro-droplets are deflected and removed; S4. Real-time on-line mass spectrometry detection: Directly introduce the single-electricity micro-droplets after screening into the mass spectrometry detection module (3), the mass spectrometry works in a positive or negative mode, collect the mass spectrometry signals and correlate the electric property parameters of the micro-droplets, and realize the synchronous acquisition of chemical composition and electric property data.

7. An external electric field screening positive and negative micro-droplets and on-line analysis device according to claim 1, characterized in that The outlet of the pneumatic atomization generation module (1) is connected to the inlet of the deflection tube (21) of the electric field screening module (2).

8. An external electric field screening positive and negative micro-droplets and on-line analysis device according to claim 1, characterized in that, The ultra-low noise high voltage generator (22) is connected to the conductive layer (23) embedded in the deflection tube (21) through a wire.

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