A system and method for condensing ultrafine particles based on bipolar electrospray

Abstract

The present invention relates to a system and method for condensing ultrafine particles based on bipolar electrospray. The system includes an electrospray generating unit, a tubular furnace heating device, a gas path regulating unit, a microfluidic unit, a high-voltage control unit, and an optical path imaging unit. Based on the electrospray principle, the present invention comprises two independent microfluidic units that propel a target solution into a generating chamber of the electrospray generating unit. The electric field gradient formed by the high-voltage control unit causes the solution to form a conical jet, generating aerosol particles with different polarities. The gas path control system regulates the airflow to cause particles of positive and negative polarity to condense in the condensation chamber. Due to the mutual attraction of the Coulomb force, the condensed particles are passed into the tubular furnace heating device, changing the three-phase interfacial tension to form stable target particles. When the electrospray generating unit is operating, the high-voltage control unit and the optical path imaging system respectively monitor the high-voltage current and the conical jet morphology to ensure the stability of the system operation.

Description

Technical Field

[0001] The present invention relates to the field of aerosol technology, and in particular to a system and method for generating ultrafine particle condensation based on bipolar electrospray. Background Art

[0002] In the field of aerosol science and technology, the preparation of aerosol particles with adjustable particle size, concentration, and composition is a very important issue. Electrospray technology is a technology that forms tiny charged droplets at the outlet of a nanospray needle under the action of a high electric field gradient and a blanket gas, and generates aerosol particles when the charge limit breaks down. Due to its adjustable particle size, concentration, and composition, it has attracted the attention of researchers. In addition, because electrospray technology can produce particles with good monodispersity, excellent flexibility, and no other by-products, electrospray has good applications and prospects in materials synthesis, thin film manufacturing, pathological biology research, electrospinning, micro-propulsion of micro-aircraft, and other fields.

[0003] Generally, researchers use unipolar electrospray aerosol generators for scientific research and production. For example, Chinese patent document CN103933901A discloses a 1-3 nm monodisperse aerosol generation system, Chinese patent document CN117096008A discloses a normal pressure secondary electrospray ionization device, and Chinese patent document CN109622224A discloses an electrospray-assisted fine particle nucleation and condensation pretreatment device and method. However, all of the above patents use unipolar spray needles, and the generated aerosols carry a large amount of charge, which requires the use of other methods to neutralize the particles to prevent rapid particle deposition.

[0004] The particles produced by unipolar single-needle electrospray contain a high level of particle charge and are easily deposited in high-voltage electric fields. Radioactive sources, Ray-X rays, corona discharge, and other methods are usually used to neutralize the charged particles, thereby eliminating the high charge level and reducing particle deposition in the cavity. These neutralization methods can cause material denaturation or cell inactivation in some special materials, such as biological cells and pharmaceuticals, which greatly limits the application scenarios of electrospray. The use of bipolar particle condensation can avoid damage from other high-intensity radioactive sources and can also achieve the effect of reducing ion charge levels. However, the condensation of bipolar particles is limited by factors such as spatial setting, electric field distribution, interference with current detection, and the influence of airflow field. Summary of the Invention

[0005] The purpose of the present invention is to provide a system and method for the condensation of ultrafine particles based on bipolar electrospray. The system and method can address the deficiencies in the prior art. By using the principle of mutual Coulomb attraction between particles with positive and negative charges and the electrospray principle and technology, the system and method can achieve self-elimination of particle charge levels, and can synthesize two different particles on a large scale. The synthesis success rate can be changed by adjusting the gas humidity level, and the long-term stable generation of aerosol particles of a specific particle size can be achieved through microcurrent monitoring and optical path imaging.

[0006] To achieve the above object, the present invention adopts the following technical solutions:

[0007] In a first aspect of the present invention, a system for generating ultrafine particle condensation based on bipolar electrospray is disclosed.

[0008] Specifically, the system includes: an electrospray generation unit, a tubular furnace heating device, a microfluidic unit, a high-voltage control unit, an optical path imaging unit and a gas path adjustment unit.

[0009] The electrospray generating unit includes a condensation chamber and a first generating chamber and a second generating chamber respectively arranged on both sides of the condensation chamber; the condensation chamber includes a condensation chamber body and a first electrode plate and a second electrode plate respectively arranged on both sides of the condensation chamber body, and the first electrode plate and the second electrode plate are respectively insulated and isolated from the condensation chamber body by a first isolation plate and a second isolation plate.

[0010] The microfluidic unit includes a first nanomist nozzle installed in the first generating chamber and a second nanomist nozzle installed in the second generating chamber; the first nanomist nozzle is used to inject liquid into the first generating chamber; the second nanomist nozzle is used to inject liquid into the second generating chamber.

[0011] The high-voltage control unit includes a positive high-voltage module connected to the first electrode plate and a negative high-voltage module connected to the second electrode plate.

[0012] The optical path imaging unit includes a first optical path imaging unit corresponding to the first nanomist nozzle and a second optical path imaging unit corresponding to the second nanomist nozzle; the first optical path imaging unit is used to collect the liquid form injected into the first generating chamber by the first nanomist nozzle; the second optical path imaging unit is used to collect the liquid form injected into the second generating chamber by the second nanomist nozzle.

[0013] The air path regulating unit is used to regulate the humidity of the air flow and mix the air with the protective gas and pass them into the first generating chamber and the second generating chamber, so that the positive and negative polarity particles are condensed in the condensation chamber.

[0014] Furthermore, the condensation chamber body is provided with condensation chamber air holes, an aerosol outlet and a temperature and humidity sensor installation hole.

[0015] The first electrode plate and the second electrode plate are respectively installed at opposite ends of the condensation chamber body, and electrode plate pores are provided on the first electrode plate and the second electrode plate; a first isolation plate is provided between the first electrode plate and the condensation chamber body, and a second isolation plate is provided between the second electrode plate and the condensation chamber body.

[0016] A temperature and humidity sensor is installed in the temperature and humidity sensor installation hole.

[0017] The condensation chamber body is also provided with a side end cover and an outlet end cover.

[0018] The condensation chamber body, the outlet end cover, the first electrode plate and the second electrode plate are made of aluminum alloy or stainless steel.

[0019] The first generating chamber, the second generating chamber, the first isolation plate and the second isolation plate are made of POM material or other insulating materials.

[0020] Furthermore, the first generating chamber and the second generating chamber have the same structure, both comprising a generating chamber body and a generating chamber air hole and a light path hole provided on the generating chamber body.

[0021] Furthermore, the microfluidic unit also includes a first microinjection pump, a first low-pressure tee and a first capillary sleeve arranged corresponding to the first nanomist nozzle, and a second microinjection pump, a second low-pressure tee and a second capillary sleeve arranged corresponding to the second nanomist nozzle.

[0022] The first low-pressure tee has a first port connected to the outlet of the first microinjection pump, a second port connected to the positive high-pressure module, and a third port used to fix the first capillary sleeve; the first nanomist spray needle is installed in the first capillary sleeve.

[0023] The second low-pressure tee has a first port connected to the outlet of the second microinjection pump, a second port connected to the negative high-pressure module, and a third port used to fix the second capillary sleeve; the second nanomist spray needle is installed in the second capillary sleeve.

[0024] Under the driving action of the first micro-injection pump, the solution in the first nano-mist spray needle is injected into the first generating chamber through the first low-pressure four-way valve; under the driving action of the second micro-injection pump, the solution in the second nano-mist spray needle is injected into the second generating chamber through the second low-pressure four-way valve.

[0025] The first capillary sleeve and the second capillary sleeve are both made of peek material or FEP material; the first capillary sleeve is clamped to the first nanomist spray needle through the first low-pressure tee; the second capillary sleeve is clamped to the second nanomist spray needle through the second low-pressure tee.

[0026] The first nanomist spray needle and the second nanomist spray needle are both made of quartz glass or stainless steel; both are hollow capillaries, and the top ends are configured as pointed tips.

[0027] Furthermore, the positive high-voltage module is connected to the first electrode plate via a first micro-current probe;

[0028] The negative high-voltage module is connected to the second electrode plate through a second micro-current probe.

[0029] Furthermore, the first optical path imaging unit includes a first imaging cavity, a first LED light source, a first plano-convex lens and a first CCD industrial camera.

[0030] The second optical path imaging unit includes a second imaging cavity, a second LED light source, a second plano-convex lens and a second CCD industrial camera.

[0031] The first imaging cavity and the second imaging cavity have the same structure, both including an imaging cavity main body, an imaging cavity air hole, a lens buckle mounting hole, a light source knob mounting hole and a microcurrent probe mounting hole arranged on the imaging cavity main body; the lens buckle mounting hole is used to install the lens buckle; the light source knob mounting hole is used to install the knob of the LED light source; the microcurrent probe mounting hole is used to install the microcurrent probe.

[0032] The first imaging cavity and the second imaging cavity are both made of insulating material. Preferably, the insulating material is POM material.

[0033] Furthermore, the gas circuit regulation unit includes a protective gas regulation module and an air regulation module; the protective gas regulation module includes a protective gas cylinder and an airflow regulation valve; the air regulation module includes an air compressor, a mass flow controller, a first three-way valve, a second three-way valve, a needle valve and a humidity bottle; the protective gas regulation module and the air regulation module are connected to the electrospray generating unit through a third three-way valve.

[0034] The gas outlet of the protective gas cylinder is connected to the first port of the third three-way valve through an airflow regulating valve; the gas outlet of the air compressor is connected to the first port of the first three-way valve through a mass flow controller, the second port of the first three-way valve is connected to the gas inlet of the humidity bottle through a needle valve, the third port of the first three-way valve is connected to the first port of the second three-way valve, the gas outlet of the humidity bottle is connected to the second port of the second three-way valve, and the third port of the second three-way valve is connected to the second port of the third three-way valve; the third port of the third three-way valve is respectively connected to the air holes in the electrospray generating unit and the optical path imaging unit.

[0035] Furthermore, the system also includes a tubular furnace heating device; the tubular furnace heating device is used to provide high temperature for the particles to undergo redox reactions.

[0036] In a second aspect of the present invention, a method for generating ultrafine particle condensation based on bipolar electrospray is disclosed. The method comprises:

[0037] Based on the electrospray principle, two nanospray needles push the target solution into the corresponding generating chamber and form a conical jet in the generating chamber;

[0038] Under the action of the electric field gradient formed by the high-voltage control unit, the conical jet generates two aerosol particles with different polarities in the generating chamber, and the two aerosol particles with different polarities enter the condensation chamber;

[0039] Two aerosol particles of different polarities enter the condensation chamber, and under the action of Coulomb force, they attract and collide with each other to form new particles, and undergo redox reactions at high temperatures to form target particles.

[0040] Furthermore, based on the electrospray principle, the two nanomist needles propel the target solution into the corresponding generating chamber and form a conical jet in the generating chamber; under the action of the electric field gradient formed by the high-voltage control unit, the conical jet generates two aerosol particles of different polarities in the generating chamber, and the two aerosol particles of different polarities enter the condensation chamber; the two aerosol particles of different polarities enter the condensation chamber and, under the action of the Coulomb force, attract and collide with each other to form new particles, and undergo an oxidation-reduction reaction at high temperature to form target particles, including:

[0041] S1. Introduce protective gas and air with a certain humidity into the first generating chamber, the second generating chamber and the condensation chamber.

[0042] The step of introducing protective gas and air into the first generating chamber, the second generating chamber and the condensation chamber comprises:

[0043] Open the protective gas cylinder and adjust the air flow regulating valve to a certain flow rate; start the air compressor to make a certain pressure at the inlet of the mass flow controller, and adjust the mass flow controller to the set flow rate; then adjust the needle valve to allow a certain proportion of air to pass into the humidity bottle, and the dry air and the air humidified by the humidity bottle are mixed through the second three-way valve. The mixed air and the protective gas are mixed through the third three-way valve and then respectively passed into the first generating chamber, the second generating chamber and the condensation chamber.

[0044] S2. Turn on the tubular furnace heating device, set a target high temperature, and make the internal temperature of the tubular furnace heating device reach the target temperature.

[0045] S3. Turn on the first LED light source and the second LED light source, and adjust the focal lengths of the first CCD industrial camera and the second CCD industrial camera.

[0046] S4. Turn on the positive high-voltage module and the negative high-voltage module, and adjust the high-voltage values ​​of the two high-voltage modules to form positive and negative high-voltage electric fields.

[0047] S5. Start the first micro-injection pump and the second micro-injection pump to push the precursor solution into the positive and negative high-voltage electric fields through the corresponding low-pressure tee, capillary sleeve, and nano-mist spray needle to form a conical jet.

[0048] At this time, the first CCD industrial camera and the second CCD industrial camera are used to capture the tip image of the corresponding nanomist needle. The captured images are used to determine whether the fluid ejected from the nanomist needle forms a conical jet state, and the current monitoring function of the positive and negative high-voltage modules is used to determine the stability of the conical jet.

[0049] S6. The gradient of the positive and negative high-voltage electric fields causes the conical jet to break, the droplets become smaller, and the electrostatic charge density of the droplet surfaces increases; when the droplets evaporate to a certain extent, the Coulomb repulsion on the droplet surface causes the droplets to explode, and the small charged droplets produced continue this process, and finally generate two aerosol particles with different polarity charges, and then the two particles with different polarity enter the condensation chamber.

[0050] Under the action of Coulomb force, different particles attract and collide with each other to form new particles, which then enter the tubular furnace heating device through the aerosol outlet. Under the high temperature of the tubular furnace heating device, redox reactions occur, changing the three-phase interfacial tension and forming target particles.

[0051] Compared with the prior art, the advantages of the present invention are:

[0052] (1) Based on the principle of electrospray, the present invention designs a "structure and device for the collision of positive and negative particles with different polarities". The self-neutralization of charged particles solves the problem of charged particle deposition in high-voltage fields, and without using an external radiation source, it solves the problem of biological cells and some special material aerosol materials being damaged and inactivated by radiation sources in the production. The two independently set generation chambers and high-voltage control units can generate particles with different polarities. The particle collision structure is used to make particles of different polarities condense and neutralize in the condensation chamber under the action of Coulomb force, so as to achieve a higher particle generation efficiency without using an external neutralization source. The ultrafine particle condensation generation system based on bipolar electrospray of the present invention can use the same or different solutions, and can realize the synthesis of two substances, such as the synthesis of hormone drugs and carrier proteins in biomedicine, such as the synthesis of dimer materials with one end hydrophobic and the other end fluorescent properties in special materials.

[0053] (2) The present invention is based on the principle of bipolar electrospray and uses a technology that is different from commercial aerosol generating devices at home and abroad to achieve particle generation. The bipolar aerosol generating end of the present invention is based on the principle of electrospray and can change the aerosol particle size by setting parameters, solving the problem of adjustable particle size in aerosol applications. The two independent microfluidic units can use different types of solutions, and the particle size of the generated particles can be adjusted by controlling the injection flow rate of the microinjection pump. Therefore, the present invention can achieve the generation of polymer particles of special particle sizes and types.

[0054] (3) The adjustable humidity gas circuit in the present invention can change the air humidity and the three-phase interfacial tension on the particle surface, thereby increasing the success rate of particle synthesis. The present invention uses an adjustable humidity gas circuit device to adjust the proportion of air entering the humidity bottle by adjusting the size of the needle valve opening to obtain air with different humidity levels. This prevents the particles from easily separating after being attracted to each other by Coulomb force in the condensation chamber, thereby increasing the particle generation efficiency. At the same time, the presence of multiple protective gases will also increase the breakdown voltage in the electrospray generation chamber, preventing the generation of corona discharge and other chemical reactions.

[0055] (4) The high-voltage control unit and optical path imaging unit in the present invention can be used to determine the stability of the entire system through current monitoring and image monitoring, achieving long-term stable generation of target aerosols. The present invention uses a CCD industrial camera in conjunction with a light source and a plano-convex lens to observe the electrospray generation state, and uses two microcurrent probes to detect the current state of the positive and negative electrode electrosprays during operation to determine the stability of the conical jet, thereby achieving a long-term stable working state.

[0056] (5) The present invention is used in conjunction with a tubular furnace heating device, which provides the high temperature conditions required for the redox reaction, thereby changing the three-phase interfacial tension of the particles after condensation and forming stable target particles.

[0057] (6) The microfluidic unit used in the present invention uses a microinjection pump for slow injection, which can meet the smaller injection flow requirements. At the same time, the use of a low-pressure four-way valve reduces the flow path pressure and can prevent flow path blockage, making it suitable for the synthesis of some expensive and rare substances. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] Figure 1 Schematic diagram of the ultrafine particle condensation generation system based on bipolar electrospray in the present invention;

[0059] Figure 2 Schematic diagram of the structure of the electrospray generating unit of the present invention;

[0060] Figure 3 Schematic diagram of the structure of the electrospray generating chamber in the present invention;

[0061] Figure 4 Schematic diagram of the structure of the electrospray imaging chamber in the present invention;

[0062] Figure 5 This is a schematic diagram of the structure of the electrospray condensation chamber, electrode plate, isolation plate, and microcurrent probe in the present invention;

[0063] Figure 6 Schematic diagram of the condensation of particles with positive and negative polarity in the electrospray condensation chamber of the present invention;

[0064] Figure 7 This is a schematic diagram of the conical jet morphology at the front end of the nanofog needle observed by the optical path imaging module;

[0065] Figure 8 This is the particle size spectrum of sucrose particles synthesized by a bipolar electrospray system.

[0066] in:

[0067] 1. Electrospray generation unit, 2. First micro-injection pump, 3. First low-pressure three-way valve, 4. First capillary sleeve, 5. First nano-mist spray needle, 6. Positive high-pressure module, 7. First plano-convex lens, 8. First CCD industrial camera, 9. Aerosol outlet, 10. Tubular furnace heating device, 11. Second CCD industrial camera, 12. Second plano-convex lens, 13. Negative high-pressure module, 14. Second capillary sleeve, 15. Second nano-mist spray needle, 16. Second low-pressure three-way valve, 17. Second generation chamber air hole, 18. Second micro-injection pump, 19. Second LED light source, 20. Condensation chamber body, 21. Second three-way valve, 22. Humidity bottle, 23. Needle valve, 24. First three-way valve, 25. Mass flow controller, 26. Air compressor, 27. Protective gas cylinder, 28. Air flow control valve, 29. Third three-way valve Valve, 30, first LED light source, 31, first generating chamber air hole, 32, condensation chamber air hole, 33, first connecting high-pressure channel, 34, first end cover, 35, first generating chamber, 36, first imaging chamber, 37, condensation chamber, 38, outlet end cover, 39, optical path imaging unit, 40, lens buckle, 41, second imaging chamber, 42, second generating chamber, 43, second end cover, 44, second connecting high-pressure channel, 45, second connecting solution channel, 46, light source knob, 47, second electrode plate, 48, second isolation plate, 49, side end cover, 50, temperature and humidity sensor mounting hole, 51, first isolation plate, 52, first electrode plate, 53 first connecting solution channel, 54, optical path hole, 55, light source knob mounting hole, 56, lens buckle mounting hole, 57, microcurrent probe mounting hole, 58, microcurrent probe. DETAILED DESCRIPTION

[0068] The present invention will be further described below with reference to the accompanying drawings:

[0069] like Figure 1~Figure 2 The system depicted here is a bipolar electrospray-based ultrafine particle condensation generation system. The system includes an electrospray generation unit 1, a microfluidics unit, a high-voltage control unit, an optical imaging unit 39, a gas flow control unit, and a tubular furnace heating device 10. The tubular furnace heating device 10 is used to provide high temperatures for the particle redox reaction. The maximum temperature of the tubular furnace heating device 10 can reach 1100°C.

[0070] The core module of the present invention is the core cavity design and supporting module design of the electrospray generating unit 1, wherein the supporting modules of the core cavity of the electrospray generating unit 1 mainly include a microfluidic unit, a high-voltage control unit, an optical path imaging unit 39, and a gas path adjustment unit; the method of the ultrafine particle condensation generation system based on bipolar electrospray is also an innovation of the present invention.

[0071] Two independent microfluidic units propel the target solution into the generating chamber of the electrospray generating unit 1. The electric field gradient created by the high-voltage control unit causes the solution to form a conical jet, generating aerosol particles with different polarities. The gas path control unit adjusts the airflow to cause the positive and negative polarity particles to condense in the condensation chamber 37. Under the action of Coulomb force, the condensed particles attract each other and pass into the tubular furnace heating device 10. Under the high temperature of the tubular furnace heating device 10, a reaction occurs, changing the three-phase interfacial tension and forming stable target particles. When the electrospray generating unit 1 is operating, the high-voltage control unit and the optical path imaging unit 39 respectively monitor the high-voltage current and the conical jet morphology to ensure the stability of the system.

[0072] The electrospray generating unit 1 includes a condensation chamber 37 and a first generating chamber 35 and a second generating chamber 42 respectively arranged on both sides of the condensation chamber 37; the condensation chamber 37 includes a condensation chamber body 20 and a first electrode plate 52 and a second electrode plate 47 respectively arranged on both sides of the condensation chamber body 20. The particles generated by the first generating chamber 35 and the second generating chamber 42 will collide due to the opposite setting of the chambers, thereby improving the synthesis efficiency of the particles.

[0073] like Figure 5 As shown, the condensation chamber body 20 is provided with a condensation chamber air hole 32, an aerosol outlet 9, and a temperature and humidity sensor mounting hole 50. The first electrode plate 52 and the second electrode plate 47 are respectively installed at opposite ends of the condensation chamber body 20, and both the first electrode plate 52 and the second electrode plate 47 are provided with electrode plate air holes. A first isolation plate 51 is provided between the first electrode plate 52 and the condensation chamber body 20, and a second isolation plate 48 is provided between the second electrode plate 47 and the condensation chamber body 20. A temperature and humidity sensor is installed in the temperature and humidity sensor mounting hole 50. The condensation chamber body 20 is also provided with a side end cover 49 and an outlet end cover 38 for fixing the generating chamber to the imaging chamber. The condensation chamber body 20, the outlet end cover 38, the first electrode plate 52, and the second electrode plate 47 are made of materials with good electrical conductivity, such as aluminum alloy or stainless steel. The first generating chamber 35 , the second generating chamber 42 , the first isolation plate 51 and the second isolation plate 48 are made of POM or other insulating materials in order to isolate the current monitoring of the two generating chambers.

[0074] like Figure 3As shown, the first generating chamber 35 and the second generating chamber 42 have the same structure, both including a generating chamber body and a generating chamber air hole and a light path hole 54 arranged on the generating chamber body. The air hole on the first generating chamber is the first generating chamber air hole 31, and the air hole on the second generating chamber is the second generating chamber air hole 17. The first generating chamber 35 and the second generating chamber 42 are both made of POM material or other insulating materials. The generating chamber air hole is annular, and there are multiple of them, which are used to allow the gas to enter the cavity of the generating chamber evenly, so as to better entrain the aerosol particles generated by the nanofog spray needle. There are two light path holes 54, and the two light path holes 54 arranged opposite to each other provide support for the light path imaging unit 39. One of the light path holes 54 is for the LED light source to provide light to pass through, and the opposite light path hole 54 is for the CCD industrial camera to capture images of the microflow morphology at the top of the nanofog spray needle, so as to facilitate the monitoring of the instrument's generating status.

[0075] like Figure 1 and Figure 2 As shown, the microfluidic unit includes a first nanomist nozzle 5 installed in the first generating chamber 35 and a second nanomist nozzle 15 installed in the second generating chamber 42; the first nanomist nozzle 5 is used to inject liquid into the first generating chamber 35; the second nanomist nozzle 15 is used to inject liquid into the second generating chamber 42.

[0076] The microfluidic unit also includes a first microinjection pump 2, a first low-pressure tee 3, and a first capillary sleeve 4, corresponding to the first nanomist needle 5; and a second microinjection pump 18, a second low-pressure tee 16, and a second capillary sleeve 14, corresponding to the second nanomist needle 15. The first low-pressure tee 3 has a first port connected to the outlet of the first microinjection pump 2, a second port connected to the positive high-pressure module 6, and a third port for securing the first capillary sleeve 4. The first nanomist needle 5 is mounted in the first capillary sleeve 4. The first low-pressure tee 3 is provided with a first high-pressure connecting channel 33 and a first solution connecting channel 53. A first end cap 34 is mounted outside the first generating chamber 35, connecting the first generating chamber 35 to the first imaging chamber 36. The second low-pressure tee 16 has a first port connected to the outlet of the second microinjection pump 18, a second port connected to the negative high-pressure module 13, and a third port for securing the second capillary sleeve 14. The second low-pressure tee 16 is provided with a second connecting high-pressure channel 44 and a second connecting solution channel 45. A second end cap 43 is installed on the outside of the second generating chamber 42, and the second end cap 43 is used to connect the second generating chamber 42 with the second imaging chamber 41. The second nanomist spray needle 15 is installed in the second capillary sleeve 14. The first capillary sleeve and the second capillary sleeve are both made of peek material or FEP material, and the capillary sleeve is clamped to the nanomist spray needle through the low-pressure tee. The first capillary sleeve 4 is clamped to the first nanomist spray needle through the first low-pressure tee 3; and the second capillary sleeve 14 is clamped to the second nanomist spray needle through the second low-pressure tee 16. The first nanomist spray needle and the second nanomist spray needle are both made of quartz glass or stainless steel; both are hollow capillaries, and the top end is set to a pointed end. The two channels of the first low-pressure tee 3 and the second low-pressure tee 16 are respectively the liquid inlets of two identical or different precursor solutions. Figure 1 In the figure, two low-pressure tees are located in a channel on the right side. They are connected to the positive high-voltage source in the positive high-voltage module 6 and the negative high-voltage source in the negative high-voltage module 13, respectively, using conductive needles. The low-pressure tees are designed to connect the functions of solution inlet, solution transportation, and connection to the high-voltage source. The deformation of the low-pressure tees clamps the liquid inlet pipeline, capillary sleeve, and nanomist needle to prevent solution leakage. In addition, the low-pressure tee allows some large-particle solutes to pass through, which can effectively reduce the occurrence of clogging.

[0077] like Figure 1 and Figure 2As shown, the high-voltage control unit includes a positive high-voltage module 6 connected to the first electrode plate 52 and a negative high-voltage module 13 connected to the second electrode plate 47. The positive high-voltage module 6 is connected to the first electrode plate 52 via a first microcurrent probe; the negative high-voltage module 13 is connected to the second electrode plate 47 via a second microcurrent probe. The voltage ranges of the positive high-voltage module 6 and the negative high-voltage module 13 are 0 to +10 kV and 0 to -10 kV, respectively.

[0078] like Figure 1 As shown, the optical imaging unit 39 includes a first optical imaging unit corresponding to the first nanomist needle 5 and a second optical imaging unit corresponding to the second nanomist needle 15. The first optical imaging unit is used to capture the morphology of the liquid injected into the first generating chamber 35 by the first nanomist needle 5; the second optical imaging unit is used to capture the morphology of the liquid injected into the second generating chamber 42 by the second nanomist needle 15. The first optical imaging unit includes a first imaging chamber 36, a first LED light source 30, a first plano-convex lens 7, and a first CCD industrial camera 8. The second optical imaging unit includes a second imaging chamber 41, a second LED light source 19, a second plano-convex lens 12, and a second CCD industrial camera 11. The LED light source and plano-convex lens in each optical imaging unit 39 are secured using a light source knob 46 and lens clip 40 for each imaging chamber, respectively. The CCD industrial camera uses a 180x objective lens for magnification, and the captured image is displayed on an electronic screen. Among them, the CCD industrial camera's image acquisition of the microflow at the tip of the nanomist spray needle can intuitively observe the solution morphology and facilitate high-pressure adjustment, which is an important means of observing the operating status of the instrument.

[0079] like Figure 4 As shown, the first imaging cavity 36 and the second imaging cavity 41 have the same structure, both including an imaging cavity body, an imaging cavity air hole arranged on the imaging cavity body, a lens buckle mounting hole 56, a light source knob mounting hole 55 and a microcurrent probe mounting hole 57. Each imaging cavity includes a light source knob 46 and a lens buckle 40. The lens buckle mounting hole 56 is used to install the lens buckle 40; the light source knob mounting hole 55 is used to install the knob of the LED light source; the microcurrent probe mounting hole 57 is used to install the microcurrent probe 58; the first imaging cavity 36 and the second imaging cavity 41 are both made of POM material or other insulating materials. The main function of the imaging cavity is to connect the airflow and imaging functions with the generating cavity, and the function of each hole is to fix and install peripherals such as LED light sources and plano-convex lenses.

[0080] The gas path regulating unit is used to regulate the gas flow so that the positive and negative polarity particles condense in the condensation chamber 37. Figure 1As shown, the gas circuit regulation unit includes a protective gas regulation module and an air regulation module; the protective gas regulation module includes a protective gas cylinder 27 and an airflow regulation valve 28; the air regulation module includes an air compressor 26, a mass flow controller 25, a first three-way valve 24, a second three-way valve 21, a needle valve 23 and a humidity bottle 22; the protective gas regulation module and the air regulation module are connected to the electrospray generating unit 1 through a third three-way valve 29. The outlet of the shielding gas cylinder 27 is connected to the first port of the third three-way valve 29 via an airflow control valve 28. The outlet of the air compressor 26 is connected to the first port of the first three-way valve 24 via a mass flow controller 25. The second port of the first three-way valve 24 is connected to the air inlet of the humidity bottle 22 via a needle valve 23. The third port of the first three-way valve 24 is connected to the first port of the second three-way valve 21. The outlet of the humidity bottle 22 is connected to the second port of the second three-way valve 21, and the third port of the second three-way valve 21 is connected to the second port of the third three-way valve 29. The third port of the third three-way valve 29 is connected to the air holes in the electrospray generating unit 1 and the optical path imaging unit 39, respectively. In the air flow control unit, the air conditioning module controls the proportion of air flowing into the humidity bottle 22 by adjusting the opening of the needle valve 23, thereby varying the humidity of the gas that finally flows into the electrospray generating unit 1. In this embodiment, carbon dioxide (CO2) is used as the shielding gas. The shielding gas is used to increase the breakdown voltage in the high-voltage electric field and prevent corona discharge. Carbon dioxide can be replaced by other protective gases with high resistivity to increase the upper limit of the breakdown voltage in the generating chamber. Other high resistivity protective gases all fall within the protection scope of the present invention.

[0081] The method of the ultrafine particle condensation generation system based on bipolar electrospray is as follows:

[0082] Based on the electrospray principle, two nanospray needles push the target solution into the corresponding generating chamber and form a conical jet in the generating chamber.

[0083] Under the action of the electric field gradient formed by the high-voltage control unit, the conical jet generates two aerosol particles with different polarities in the generating chamber, and the two aerosol particles with different polarities enter the condensation chamber 37 .

[0084] The two aerosol particles of different polarities enter the condensation chamber 37 and attract and collide with each other under the action of Coulomb force to form new particles, and then undergo redox reaction at high temperature to form target particles.

[0085] Furthermore, based on the electrospray principle, the two nanomist needles push the target solution into the corresponding generating chamber and form a conical jet in the generating chamber; under the action of the electric field gradient formed by the high-voltage control unit, the conical jet generates two aerosol particles of different polarities in the generating chamber, and the two aerosol particles of different polarities enter the condensation chamber 37; the two aerosol particles of different polarities enter the condensation chamber 37, and under the action of the Coulomb force, they attract and collide with each other to form new particles, and undergo an oxidation-reduction reaction at high temperature to form target particles, including:

[0086] S1. Protective gas and air with a certain humidity are introduced into the first generating chamber 35, the second generating chamber 42 and the condensation chamber 37. The air with a certain humidity can form a protective water film after the particles are synthesized in the condensation chamber 37, which will not separate easily, thereby increasing the synthesis efficiency.

[0087] The protective gas and air are introduced into the first generating chamber 35, the second generating chamber 42 and the condensation chamber 37, including:

[0088] Open the protective gas cylinder 27 and adjust the airflow regulating valve 28 to a certain flow rate; start the air compressor 26 to make a certain pressure at the inlet of the mass flow controller 25, and adjust the mass flow controller 25 to the set flow rate; then adjust the needle valve 23 to allow a certain proportion of air to pass into the humidity bottle 22, and the dry air and the air humidified by the humidity bottle 22 are mixed through the second three-way valve 21. The mixed air and the protective gas are mixed through the third three-way valve 29 and then respectively passed into the first generating chamber 35, the second generating chamber 42 and the condensation chamber 37.

[0089] S2. Turn on the tubular furnace heating device 10, set a target high temperature, and wait for a period of time so that the internal temperature of the tubular furnace heating device 10 reaches a balanced target temperature.

[0090] S3. Turn on the LED light source and adjust the focal length of the CCD industrial camera so that the CCD industrial camera can well capture the tip structure of the nanofog needle.

[0091] S4. Turn on the positive high-voltage module 6 and the negative high-voltage module 13, and adjust the high-voltage value to be slightly lower than the predetermined target high-voltage value.

[0092] S5. Start the microinjection pump and push two identical or different precursor solutions through the low-pressure tee, capillary sleeve, and nanomist needle into the positive and negative high-voltage electric fields. A CCD industrial camera is used to observe whether the fluid forms a conical jet, and the current monitoring function of the positive and negative high-voltage module 13 is used to determine the stability of the conical jet.

[0093] Two identical or different precursor solutions are prepared using isopropyl alcohol (IPA) and water in varying proportions, and an appropriate amount of ammonium acetate (CH3COONH4) is added. The isopropyl alcohol (IPA) modifies the surface tension of the solution, while the ammonium acetate (CH3COONH4) modulates the conductivity of the solution. Other substances that modify the surface tension of a liquid and regulate its conductivity also fall within the scope of this invention.

[0094] S6. The gradient of the high-voltage electric field causes the conical jet to break up, the droplets become smaller, and the electrostatic charge density of the droplet surfaces increases. When the droplets evaporate to a certain extent, the Coulomb repulsion on the droplet surface causes the droplets to explode, and the small charged droplets produced continue this process. Finally, two aerosol particles with different polarities are generated respectively. Subsequently, the two particles with different polarities enter the condensation chamber 37 of the electrospray generator. Due to the Coulomb force, the different particles attract each other and collide to form new particles. Then, they enter the tubular furnace heating device 10 through the aerosol outlet 0. Under the high temperature of the tubular furnace heating device 10, an oxidation-reduction reaction occurs, changing the three-phase interfacial tension to form stable target particles.

[0095] like Figure 7 The figure shows the schematic diagram of the conical jet morphology at the front end of the nanofog needle observed by a single optical imaging module. Figure 7 The stable conical jet state of electrospray can be seen. The aerosol particle size generated by a single conical jet and the current monitored by the microcurrent probe conform to the following formula.

[0096] Current:

[0097] Particle size:

[0098] in: is the solution conductivity; is the dielectric constant; is the surface tension; is the liquid flow rate; is the charge relaxation time; is a dimensionless function of uniform magnitude.

[0099] like Figure 6 As shown, particles with positive and negative charges are generated in the generating chamber by two nanomist needles, and are attracted to each other by Coulomb force in the condensation chamber 37 to form target particles. In this embodiment, a 1% (v / v) sucrose solution is used. The solution is prepared by deionized water and isopropyl alcohol IPA in a ratio of 1:1 (v / v), and ammonium acetate CH3COONH4 is added to adjust the solution conductivity to 300uC / cm. A stable conical jet morphology is formed under a high voltage electric field of ±2.426kV. At this time, the negative electrode current fluctuates between -178nA±2nA and the positive electrode current fluctuates between +206nA±2nA. The air humidity is adjusted to 55.8%RH. Figure 8 As shown, the generated particles are scanned by the SMPS particle size spectrometer, and the 41 nm particles generated at the positive and negative ends are synthesized into 61.5 nm target particles in the condensation chamber 37 .

[0100] The present invention is based on the electrospray principle. Two independent microfluidic units push the target solution into the generating chamber of the electrospray generating unit 1; the electric field gradient formed by the high-voltage control unit causes the solution to form a conical jet to generate aerosol particles with different polarities. The air path control system adjusts the airflow to make the positive and negative polarity particles condense in the condensation chamber 37. Due to the mutual attraction of Coulomb force, the condensed particles are passed into the tubular furnace heating device 10 to change the three-phase interfacial tension to form stable target particles; when the electrospray generating unit 1 is working, the high-voltage control unit and the optical path imaging system will respectively monitor the high-voltage current and the conical jet morphology to ensure the stability of the system operation.

[0101] The bipolar electrospray in the present invention is not a simple superposition of two polar electrosprays. How to invent a system and method for condensing ultrafine particles based on bipolar electrospray requires comprehensive consideration of electric field interference, current interference, gas path settings, and the rationality and effectiveness of imaging acquisition settings, which are not found in existing inventions. The present invention is based on the electrospray principle and uses a bipolar electrospray neutralization method to invent a system and method for condensing ultrafine particles based on bipolar electrospray to solve the problems mentioned in the background technology. In addition, since the use of high-voltage sources of different polarities will cause particles to carry charges of different polarities, and particles of different polarities will attract each other and condense, in the synthesis of polymer materials for some special drugs, electrospray technology has unparalleled prospects due to the generation of charged particles, adjustable particle size, and the absence of by-products. Therefore, the present invention is to enable the electrospray device to abandon its dependence on the neutralization source and provide a new method for the production and manufacture of drugs and polymer materials with special particle sizes that require carriers.

[0102] Generally speaking, the ultrafine particle condensation generation device and system based on bipolar electrospray designed by the present invention is a brand-new aerosol particle generation scheme, which is significantly different from the existing schemes listed in the background technology in terms of principle and setting. There are currently no instruments that are identical or similar to the present invention at home and abroad. The present invention is based on the principle of electrospray aerosol generator in some settings, but the overall system is a brand-new design. Although some details are existing means, these settings are intended to serve the overall generation scheme and to achieve better generation effects. It is not a simple patchwork of technologies.

[0103] The core structure of the bipolar electrospray system is also a key innovation of the present invention. The design of the condensation chamber 37, the two generation chambers, and the various supporting interfaces are core components of the present invention's design based on the principle of "positive and negative collision of particles with different polarities." The nanomist needle installation and solution flow path design in the microfluidic unit; the microcurrent probe for current monitoring and high-voltage electric field isolation in the high-voltage control unit; the light source and imaging lens design in the optical imaging unit 39; and the humidity control and shielding gas mixing design in the gas imaging unit all serve to support the core electrospray module of the present invention. The proposed bipolar electrospray-based ultrafine particle condensation generation system and method have important applications in materials manufacturing, pharmaceutical production, and environmental research due to its unique principles. For example, the present invention provides new means and technologies for the synthesis of dimers (with different properties at both ends) in materials, the synthesis of therapeutic drugs and carrier proteins, and the synthesis and growth of particles in the environment.

[0104] The above-described embodiments are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. An ultrafine particle condensation generation system based on bipolar electrospray, characterized in that: The system includes: an electrospray generation unit, a microfluidic unit, a high-voltage control unit, an optical imaging unit and a gas path adjustment unit; The electrospray generating unit includes a condensation chamber and a first generating chamber and a second generating chamber respectively arranged on both sides of the condensation chamber; the condensation chamber includes a condensation chamber body and a first electrode plate and a second electrode plate respectively arranged on both sides of the condensation chamber body; The microfluidic unit includes a first nanomist nozzle installed in the first generating chamber and a second nanomist nozzle installed in the second generating chamber; the first nanomist nozzle is used to inject liquid into the first generating chamber; the second nanomist nozzle is used to inject liquid into the second generating chamber; The high-voltage control unit includes a positive high-voltage module connected to the first electrode plate and a negative high-voltage module connected to the second electrode plate; The optical path imaging unit includes a first optical path imaging unit corresponding to the first nanomist nozzle and a second optical path imaging unit corresponding to the second nanomist nozzle; the first optical path imaging unit is used to collect the form of the liquid injected into the first generating chamber by the first nanomist nozzle; the second optical path imaging unit is used to collect the form of the liquid injected into the second generating chamber by the second nanomist nozzle; The air path regulating unit is used to regulate the humidity of the air flow and mix the air with the protective gas and pass it into the first generating chamber and the second generating chamber, so that the positive and negative polarity particles are condensed in the condensation chamber; The condensation chamber body is provided with a condensation chamber air hole and an aerosol outlet; the first electrode plate and the second electrode plate are respectively installed at opposite ends of the condensation chamber body, and the first electrode plate and the second electrode plate are both provided with electrode plate air holes; the first generating chamber and the second generating chamber each include a generating chamber body and a generating chamber air hole and an optical path hole provided on the generating chamber body; The gas circuit regulation unit includes a protective gas regulation module and an air regulation module; the protective gas regulation module includes a protective gas cylinder and an airflow regulation valve; the air regulation module includes an air compressor, a mass flow controller, a first three-way valve, a second three-way valve, a needle valve and a humidity bottle; the protective gas regulation module and the air regulation module are connected to the electrospray generation unit through a third three-way valve.

2. The ultrafine particle condensation generation system based on bipolar electrospray according to claim 1 is characterized in that: The condensation chamber body is provided with a temperature and humidity sensor mounting hole; A temperature and humidity sensor is installed in the temperature and humidity sensor installation hole.

3. The ultrafine particle condensation generation system based on bipolar electrospray according to claim 1, characterized in that: The condensation chamber body is also equipped with a side end cover and an outlet end cover; The condensation chamber body, the outlet end cover, the first electrode plate and the second electrode plate are made of aluminum alloy or stainless steel; The first generating chamber and the second generating chamber are made of insulating material, and the insulating material is POM material.

4. The ultrafine particle condensation generation system based on bipolar electrospray according to claim 1, characterized in that: The microfluidic unit further includes a first microinjection pump, a first low-pressure tee, and a first capillary sleeve arranged corresponding to the first nanomist nozzle, and a second microinjection pump, a second low-pressure tee, and a second capillary sleeve arranged corresponding to the second nanomist nozzle; The first low-pressure tee, whose first port is connected to the outlet of the first microinjection pump, the second port is connected to the positive high-pressure module, and the third port is used to fix the first capillary sleeve; The first nanomist spray needle is installed in the first capillary sleeve; The second low-pressure tee, whose first port is connected to the outlet of the second microinjection pump, the second port is connected to the negative high-pressure module, and the third port is used to fix the second capillary sleeve; the second nanomist spray needle is installed in the second capillary sleeve; The first capillary sleeve and the second capillary sleeve are both made of peek material or FEP material; the first capillary sleeve is clamped to the first nanomist spray needle through the first low-pressure tee; Through the second low-pressure T-joint, the second capillary sleeve is clamped to the second nanomist needle; Under the driving action of the first micro-injection pump, the solution in the first nano-mist spray needle is injected into the first generating chamber through the first low-pressure four-way valve; Under the driving action of the second micro-injection pump, the solution in the second nano-mist spray needle is injected into the second generating chamber through the second low-pressure four-way valve; The first nanomist spray needle and the second nanomist spray needle are both made of quartz glass or stainless steel; both are hollow capillaries, and the top ends are configured as pointed tips.

5. The ultrafine particle condensation generation system based on bipolar electrospray according to claim 1, characterized in that: The positive high-voltage module is connected to the first electrode plate via a first micro-current probe; The negative high-voltage module is connected to the second electrode plate through a second micro-current probe.

6. The ultrafine particle condensation generation system based on bipolar electrospray according to claim 1, characterized in that: The first optical path imaging unit includes a first imaging cavity, a first LED light source, a first plano-convex lens and a first CCD industrial camera; The second optical path imaging unit includes a second imaging cavity, a second LED light source, a second plano-convex lens and a second CCD industrial camera; The first imaging cavity and the second imaging cavity have the same structure, and both include an imaging cavity body, an imaging cavity air hole, a lens buckle mounting hole, a light source knob mounting hole, and a microcurrent probe mounting hole provided on the imaging cavity body; the lens buckle mounting hole is used to mount the lens buckle; the light source knob mounting hole is used to mount the knob of the LED light source; and the microcurrent probe mounting hole is used to mount the microcurrent probe. The first imaging cavity and the second imaging cavity are both made of insulating material, and the insulating material is POM material.

7. The ultrafine particle condensation generation system based on bipolar electrospray according to claim 1, characterized in that: The gas outlet of the protective gas cylinder is connected to the first port of the third three-way valve through an airflow regulating valve; the gas outlet of the air compressor is connected to the first port of the first three-way valve through a mass flow controller, the second port of the first three-way valve is connected to the gas inlet of the humidity bottle through a needle valve, the third port of the first three-way valve is connected to the first port of the second three-way valve, the gas outlet of the humidity bottle is connected to the second port of the second three-way valve, and the third port of the second three-way valve is connected to the second port of the third three-way valve; the third port of the third three-way valve is respectively connected to the air holes in the electrospray generating unit and the optical path imaging unit.

8. The ultrafine particle condensation generation system based on bipolar electrospray according to claim 2, characterized in that: The system also includes a tubular furnace heating device; The tubular furnace heating device is used to provide high temperature for the particles to undergo redox reactions.

9. The method of the ultrafine particle condensation generation system based on bipolar electrospray according to any one of claims 1 to 8, characterized in that: The method includes: Based on the electrospray principle, two nanospray needles push the target solution into the corresponding generating chamber and form a conical jet in the generating chamber; Under the action of the electric field gradient formed by the high-voltage control unit, the conical jet generates two aerosol particles with different polarities in the generating chamber, and the two aerosol particles with different polarities enter the condensation chamber; Two aerosol particles of different polarities enter the condensation chamber, and under the action of Coulomb force, they attract and collide with each other to form new particles, and undergo redox reactions at high temperatures to form target particles.

10. The method of the ultrafine particle condensation generation system based on bipolar electrospray according to claim 9, characterized in that: Based on the electrospray principle, two nano-mist spray needles push the target solution into the corresponding generating chamber and form a conical jet in the generating chamber; under the action of the electric field gradient formed by the high-voltage control unit, the conical jet generates two aerosol particles of different polarities in the generating chamber, and the two aerosol particles of different polarities enter the condensation chamber; the two aerosol particles of different polarities enter the condensation chamber and attract and collide with each other under the action of Coulomb force to form new particles, and undergo redox reaction at high temperature to form target particles, including: S1. Introducing protective gas and air with a certain humidity into the first generating chamber, the second generating chamber, and the condensation chamber; S2. Turn on the tubular furnace heating device and set the target high temperature so that the internal temperature of the tubular furnace heating device reaches the target temperature; S3, turning on the first LED light source and the second LED light source, and adjusting the focal lengths of the first CCD industrial camera and the second CCD industrial camera; S4. Turn on the positive high-voltage module and the negative high-voltage module, and adjust the high voltage values ​​of the two high-voltage modules to form positive and negative high-voltage electric fields; S5. Start the first micro-syringe pump and the second micro-syringe pump to push the precursor solution into the positive and negative high-voltage electric fields through the corresponding low-pressure tee, capillary sleeve, and nano-mist spray needle to form a conical jet; At this time, the first CCD industrial camera and the second CCD industrial camera are used to capture images of the corresponding nanomist needle tip. The captured images are used to determine whether the fluid ejected from the nanomist needle forms a conical jet state, and the current monitoring function of the positive and negative high-voltage modules is used to determine the stability of the conical jet. S6. The gradients of the positive and negative high-voltage electric fields cause the conical jet to break up, the droplets to become smaller, and the electrostatic charge density on the droplet surfaces increases. When the droplets evaporate to a certain extent, the Coulomb repulsion on the droplet surfaces causes the droplets to explode, and the resulting small charged droplets continue this process, ultimately generating two types of aerosol particles with different charges. Subsequently, the two types of particles with different polarities enter the condensation chamber. Under the action of Coulomb force, different particles attract and collide with each other to form new particles, which then enter the tubular furnace heating device through the aerosol outlet. Under the high temperature of the tubular furnace heating device, redox reactions occur, changing the three-phase interfacial tension and forming target particles.

Images