A particle size-resolved nano-particle collection device and method

Abstract

The present invention discloses a particle size-resolved nano-particle collection device and method, belonging to the technical field of atmospheric particle collection. In the collection device of the present invention, a collection chamber is provided inside the collector main body, a cold plate is arranged at the top of the collection chamber, a hot plate is arranged at the bottom of the collection chamber, the collection chamber has an air inlet communicating with the atmosphere, and an air pump is connected to the outlet of the collection chamber; both of the two membrane support platforms are arranged at the bottom end of the membrane support frame, a collection hole penetrating from the top of the collector main body to the inside of the collection chamber is provided on the collector main body, a protection chamber is also provided on the collector main body, and a membrane support frame driving part is used to exchange the positions of the collection hole and the two membrane support platforms in the protection chamber. The present invention can realize the collection of nano-scale particles, has high sampling efficiency, and a wide range of particle sizes of the collected particles.

Description

Technical Field

[0001] The present invention relates to the technical field of atmospheric particulate matter collection, and particularly relates to a size-resolved nano particulate matter collection device and method. Background Art

[0002] Atmospheric fine particulate matter has a significant impact on human health, air quality, and climate change. The environmental impact of particulate matter is closely related to its particle size. For example, nano particulate matter has the characteristics of small particle size and high concentration, and is more likely to penetrate deep into the alveoli through the respiratory system, which may cause relatively serious impacts on human health. In order to accurately evaluate the potential risks of nano particulate matter to health and understand its physicochemical properties, it is very important to collect particulate matter by particle size. Single particle analysis is an important technical means to characterize the properties of particulate matter, and the microscopy-based single particle analysis technology plays a key role in it. In order to carry out such analysis, it is a crucial prerequisite to collect single particles of different particle sizes from a complex environment. Traditional single particle collection devices mostly use the method of inertial impaction. Since large particle size particulate matter has a large inertia and can be collected by impaction, while nano-sized particulate matter has a small inertia and will flow away with the air flow, it is difficult to rely on the inertial impaction method of particulate matter to collect. Therefore, the existing single particle collection devices currently cannot achieve the collection of nano-sized particulate matter. Summary of the Invention

[0003] The purpose of the present invention is to overcome the problems in the prior art and provide a size-resolved nano particulate matter collection device and method that can achieve the collection of nano-sized particulate matter.

[0004] A size-resolved nano particulate matter collection device provided by the present invention includes a collector, which includes a collector main body, a cold plate and a hot plate. A collection chamber is provided inside the collector main body. The cold plate is arranged at the top of the collection chamber, and the hot plate is arranged at the bottom of the collection chamber. The collection chamber has an air inlet communicating with the atmosphere, and an air pump is connected to the outlet of the collection chamber. When the size-resolved nano particulate matter collection device of the present invention is collecting, it uses the interaction between gas molecules and particulate matter to generate a certain thermophoretic velocity in the direction from the hot plate to the cold plate , and while the particulate matter moves forward with the gas, it also moves towards the cold plate and finally hits the cold plate.

[0005] Collector, including a film support frame, two film support platforms and a film support frame driving part. Both of the two film support platforms are arranged at the bottom end of the film support frame. The film support platform is used to carry a sample film, and the sample film is located at the bottom of the film support platform. A collection hole penetrating from the top of the collector body to the inside of the collection cavity is provided on the collector body. A protection cavity is also provided on the collector body. The two film support platforms are respectively located in the collection hole and the protection cavity. The film support frame driving part is used to exchange the positions of the two film support platforms in the collection hole and the protection cavity. It can realize the alternative collection of nano-particles on the two film support platforms, and the sample film collected with nano-particles can be directly used for subsequent detection and analysis.

[0006] Preferably, at least one semiconductor refrigerating sheet is arranged in the film support platform. A film support plate made of the same material as the cold plate is provided at the bottom of the film support platform. The sample film is located at the bottom of the film support plate. The semiconductor refrigerating sheet is used to provide cold for the film support plate, and a radiator for dissipating heat and cooling the semiconductor refrigerating sheet is provided on the film support platform.

[0007] Preferably, the film support frame driving part includes:

[0008] A transmission shaft, including a fixed shaft, a movable shaft and a first servo motor arranged vertically. The top of the fixed shaft is fixedly connected with the first servo motor. A square hole is axially opened at the bottom of the fixed shaft. The top of the movable shaft is a square shaft head. The square shaft head is located in the square hole, and a compression spring is arranged between the square shaft head and the square hole. The film support frame is connected to the bottom end of the movable shaft.

[0009] A lever, including a collar, a connecting rod and a rolling part. The rolling part and the collar are respectively located at both ends of the connecting rod. The collar is sleeved on the movable shaft, and one side of the collar is fixed by a shoulder and the other side is fixed by a circlip.

[0010] A cam assembly, including a cam and a second servo motor for driving the cam to rotate. A cam groove is provided on the outer surface of the cam. The rolling part is embedded in the cam groove, and the rolling part can roll along the cam groove when the cam rotates.

[0011] Preferably, temperature sensors are provided on both the cold plate and the hot plate.

[0012] Preferably, a regulating valve for regulating the intake air flow is installed at the intake port of the air pump.

[0013] Preferably, a sealing ring is provided on the outer periphery of the film support platform or the inner walls of the collection hole and the protection cavity.

[0014] The present invention also provides a collection method using the above-mentioned particle size-resolved nano-particle collection device, including the following steps:

[0015] When the particle size of the particles to be collected When the time is

[0016] , where λ is the mean free path of gas molecules; T is the ambient temperature, T is the temperature gradient, is the viscosity of the gas, is the gas density;

[0017] When the particle size of the particles to be collected the thermophoretic velocity generated by the nano-particles is:

[0018] ; where H is a coefficient, is the correction factor;

[0019] When the distance between the cold plate and the hot plate is determined, a °C / mm temperature gradient is created between the cold plate and the hot plate, The value range of is 1 to 2. When , calculate the maximum thermophoretic velocity of the nano-particles entering the collection chamber. According to , obtain the shortest time for the nano-particles to hit the cold plate, where a is the distance between the two plates; when the velocity of the nano-particles entering the collection chamber is constant, the shortest horizontal movement distance of the particles between the cold plate and the hot plate, At the shortest distance set the first sample film to collect particles with a particle size ;

[0020] For particles with a particle size , the particles will hit the sample film behind the first sample film, realizing the collection of different particle sizes.

[0021] Preferably, the correction factor :

[0022] , where , , , is the particle size of the particles.

[0023] Preferably, the definition of the coefficient H: , where is the thermal conductivity of the particles, is the thermal conductivity of the surrounding gas, is the particle size of the particulate matter.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows: A particle size-resolved nano particulate matter collection device proposed by the present invention includes a collector and a collector. By designing a cold plate and a hot plate arranged up and down in the collector body, the particulate matter following the gas into the space between the cold plate and the hot plate can obtain a thermophoretic velocity. At the same time, by utilizing the difference in thermophoretic velocities of nano particulate matters with different particle sizes, the collection of nano particulate matters in different particle size ranges is realized. The present invention also directly places the sample film at a determined position on the cold plate through the designed collector, and through the joint cooperation of the film support and the film support driving part, the replacement and protection of the sample film are realized, the sampling efficiency is improved, and the collected nano particulate matters are directly collected on the sample film and can be directly used for subsequent detection and analysis.

[0025] A particle size-resolved nano particulate matter collection device proposed by the present invention has significant advantages compared with traditional atmospheric particulate matter collection devices. It can effectively synchronously collect atmospheric nano particulate matters with different particle sizes within a certain range, thus providing a new technical means for studying and evaluating the impact of atmospheric particulate matter on health. Through this collection method, researchers can more carefully analyze the composition and morphology of nano particulate matters with different particle sizes, and further deeply understand their potential hazards to human health.

[0026] The collection method of the particle size-resolved nano particulate matter collection device of the present invention can calculate the landing position of nano particulate matters within this size range on the sample film according to the particle size, thermophoretic velocity of the nano particulate matters to be collected, and the temperature gradient between the cold plate and the hot plate, etc., so that the sample film can collect nano particulate matters corresponding to the particle size; in addition, the present invention can also change the thermophoretic velocity by regulating the gas flow rate or regulating the temperature gradient between the cold plate and the hot plate, so that nano particulate matters with a wider range of particle sizes can be collected without changing the position of the collector of the present invention. Brief Description of the Drawings

[0027] Figure 1 is a schematic diagram of the particulate matter collection principle of the present invention.

[0028] Figure 2 is a schematic diagram of the external structure of an embodiment of the present invention.

[0029] Figure 3 is a schematic diagram of the internal structure of an embodiment of the present invention.

[0030] Figure 4 is a schematic diagram of the structure of the collector of an embodiment of the present invention.

[0031] Figure 5 is a schematic diagram of the structure of the collector of an embodiment of the present invention.

[0032] Figure 6 Schematic structural diagram of the lever in the embodiment of the present invention;

[0033] Figure 7 Schematic structural diagram of the connection between the lever and the movable shaft in the embodiment of the present invention.

[0034] Explanation of reference numerals:

[0035] 1. Collector main body, 2. Cold plate, 3. Hot plate, 4. Air inlet, 5. Air pump, 6. Film support, 7. Film support table, 8. Collection hole, 9. Protection cavity, 10. Transmission shaft, 101. Fixed shaft, 102. Movable shaft, 103. First servo, 11. Lever, 111. Collar, 112. Connecting rod, 113. Rolling part, 12. Cam assembly, 121. Cam, 122. Second servo, 123. Cam groove, 13. Box body, 14. Semiconductor refrigeration sheet, 15. Film support plate, 16. Radiator, 17. Snap ring. Detailed implementation manners

[0036] To make the objectives, technical solutions and advantages of the embodiments of the present disclosure clearer, the technical solutions of the embodiments of the present disclosure will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present disclosure. Apparently, the described embodiments are some but not all of the embodiments of the present disclosure. All other embodiments obtained by those of ordinary skill in the art based on the described embodiments of the present disclosure without creative efforts shall fall within the scope of protection of the present disclosure.

[0037] Unless otherwise defined, the technical terms or scientific terms used herein shall have the ordinary meanings understood by those of ordinary skill in the art to which the present disclosure pertains. The "first", "second" and similar terms used in the present disclosure do not denote any order, quantity or importance, but are only used to distinguish different components. The terms such as "including" or "comprising" mean that the elements or objects appearing before "including" or "comprising" cover the elements or objects listed after "including" or "comprising" and their equivalents, and do not exclude other elements or objects. The terms such as "connected" or "coupled" are not limited to physical or mechanical connections, but may include electrical connections, whether direct or indirect. The terms such as "upper", "lower", "left" and "right" are only used to represent relative positional relationships, and when the absolute position of the object being described changes, the relative positional relationships may also change accordingly.

[0038] A nanoparticle collection device with particle size resolution provided in this embodiment includes a collector and a collector. The collector includes a collector main body 1, a cold plate 2, and a hot plate 3. A collection chamber is provided in the collector main body 1. The cold plate 2 is provided at the top of the collection chamber, and the hot plate 3 is provided at the bottom of the collection chamber. The collection chamber has an air inlet 4 communicating with the atmosphere, and an air pump 5 is connected to the outlet of the collection chamber. When collecting nanoparticles, the gas carrying nanoparticles enters the collection chamber through the air inlet 4 of the collection chamber. Since the cold plate 2 is designed at the top of the collection chamber and the hot plate 3 is provided at the bottom, as Figure 1 shown, the cold plate 2 and the hot plate 3 are parallel and maintain a certain distance a. There is a temperature gradient T between the two plates of the cold plate 2 and the hot plate 3. When the gas carrying a large number of particles flows along the collection chamber at a certain speed , due to the temperature gradient between the cold plate 2 and the hot plate 3, the gas molecules in the hotter region have higher kinetic energy than those in the colder region, resulting in uneven momentum transfer caused by the collision of the gas with the particle surface. The momentum transferred by the collision on the surface of the particle facing the hot plate 3 is greater than that on the opposite side. Therefore, the interaction between the gas molecules and the particles causes a certain thermophoretic velocity in the direction from the hot plate 3 to the cold plate 2 . This makes the particles move towards the cold plate 2 while moving forward with the gas and finally hit the cold plate 2. It should be noted that the nanoscale particles in this embodiment refer to particles with a size of, for example, 10 nm to 300 nm. Among them, when collecting nanoparticles with a size of 66 nm to 300 nm, particle size resolution can be achieved, while nanoparticles with a size of 10 nm to 66 nm can be effectively collected, but it is difficult to resolve the particle size.

[0039] Compared with the traditional method of collecting particles by high-speed particle impact, high-speed particle impact on the membrane may cause fragmentation and change the morphology of the particles. However, this problem does not exist in this embodiment. Secondly, in the traditional method of collecting particles by high-speed particle impact, only when the particle size reaches a certain size can inertial sampling be used. If the particle size is too small, the particle inertia is small and it will flow away with the air flow, making it difficult to collect. The above-mentioned collection method in this embodiment can collect smaller-sized particles compared to this traditional collection method.

[0040] Such as Figure 3 , Figure 4 and Figure 5As shown in the figure, the collector of this embodiment includes a film support frame 6, two film support platforms 7, and a film support frame driving part. Both of the two film support platforms 7 are arranged at the bottom end of the film support frame 6. A collection hole 8 that penetrates from the top of the collector body 1 to the inside of the collection cavity is provided on the collector body 1. A protection cavity 9 is also provided on the collector body 1. The two film support platforms 7 are respectively located in the collection hole 8 and the protection cavity 9. The film support frame driving part is used to exchange the positions of the two film support platforms 7 in the collection hole 8 and the protection cavity 9. More specifically, the film support frame driving part makes the film support frame 6 move up and down or drives the film support frame 6 to rotate, so that when one film support platform 7 is located in the collection hole 8, the other film support platform 7 is located in the protection cavity 9. In this way, the sampling of the sample films on the two film support platforms 7 can be continuously completed. In this embodiment, the bottom surfaces of the two film support platforms 7 are located on the same horizontal plane. As a preferred method, the bottom surface of the film support plate 15 in the collection hole 8 is located on the same horizontal plane as the lower surface of the cold plate 2. At this time, the difference between the protection cavity 9 and the collection hole 8 is that the protection cavity 9 is a blind hole, that is, the lower opening of the protection cavity 9 is closed. As Figure 4 shown in the figure, the protection cavity 9 is located on the side of the collector body 1, avoiding the area where the collection cavity and the cold plate 2 are located, so as to avoid affecting sample collection.

[0041] Please refer to again Figure 4 , in this embodiment, the horizontal cross-sections of both the protection cavity 9 and the collection hole 8 are rectangular. However, it should be understood that the specific shape of the horizontal cross-section is not limited to this, and it can also be other shapes. The two film support platforms 7 of this embodiment are adapted to the sizes and shapes of the protection cavity 9 and the collection hole 8. In order to improve the fitting sealing performance between the two film support platforms 7 and the protection cavity 9 and the collection hole 8, sealing rings can be designed on the outer edges of the two film support platforms 7, or sealing rings can be designed on the inner walls of the protection cavity 9 and the collection hole 8 to ensure the sealing performance after fitting. On this basis, the film support platform 7 of this embodiment includes a film support plate 15 and a sample film covering the film support plate 15. The nano-particles collected on the sample film can be directly used for subsequent detection and analysis. In this embodiment, the sample film is a conventional particulate sample film in the prior art. In order to collect nano-particles with different particle sizes, multiple sample films can be designed on the film support plate 15 of the film support platform 7 along the gas flow direction. Different sample films collect nano-particles in different particle size ranges. The length of the film support platform 7 in this embodiment is about 30 mm, and it can carry 10 sample films.

[0042] Please refer to again Figure 4 , the specific structure of the collector of this embodiment can be as Figure 4As shown in the figure, it includes a collector body 1, a cold plate 2, a cold plate protection plate, a hot plate 3, and a hot plate protection plate. The collection chamber is arranged on one side of the collector body 1. The collection chamber communicates with the outside through an air inlet 4 and an air outlet. There is a cold plate slot on the collection chamber, and a hot plate slot is provided below. The cold plate 2 and the cold plate protection plate are successively arranged in the cold plate slot and fixed to the collector body 1 by screws. The collection hole 8 is provided on the cold plate 2 and communicates with the sampling chamber. There are also corresponding holes on the cold plate protection plate of the cold plate 2. The hot plate 3 and the hot plate protection plate are successively arranged in the hot plate slot and fixed to the collector body 1 by screws. The hot plate 3 is heated by a resistance wire. Temperature sensors are respectively provided on the cold plate 2 and the hot plate 3. The air inlet 4, the air outlet, the cold plate 2, the hot plate 3, and the cavity of the collector body 1 together form a gas flow channel. Sealing strips are respectively provided on the cold plate 2, the cold plate protection plate, the hot plate 3, and the hot plate protection plate to ensure the tightness of the gas flow channel. The protection chamber 9 is symmetrically designed with the collection hole 8.

[0043] In this embodiment, at least one semiconductor refrigerating sheet 14 is arranged in each of the film supporting platforms 7, as Figure 5 shown, there are two, but it should be understood that the specific number is not limited. The number of the semiconductor refrigerating sheets 14 can also be 1, 3, etc., as long as the use requirements are met. Each semiconductor refrigerating sheet 14 is connected with a radiator 16. The radiator 16 is located on the film supporting platform 7. More specifically, two positioning holes are arranged on each film supporting platform 7. The semiconductor refrigerating sheet 14 is embedded in the positioning hole, and its refrigerating surface is fixedly installed on the film supporting plate 15. The two semiconductor refrigerating sheets 14 on the same film supporting platform 7 are connected in series and then connected to a 12V DC power supply. Each radiator 16 is respectively fixedly installed on the heat dissipation surface of the semiconductor refrigerating sheet 14. A film supporting plate 15 is also provided on the bottom surface of the film supporting platform 7. The sample film for collecting particulate matter is arranged on the bottom surface of the film supporting plate 15. The semiconductor refrigerating sheet 14 is used to provide cold for the film supporting plate 15, and the radiator 16 is used to dissipate heat and cool down the semiconductor refrigerating sheet 14.

[0044] As another preferred mode of this embodiment, the film supporting frame driving part of this embodiment includes: a transmission shaft 10, a lever 11, and a cam assembly 12; wherein the transmission shaft 10 includes a fixed shaft 101, a movable shaft 102, and a first servo motor 103 arranged vertically; the top of the fixed shaft 101 is fixedly connected with the first servo motor 103. A square hole is axially opened at the bottom of the fixed shaft 101. The top of the movable shaft 102 is a square shaft head. The square shaft head is located in the square hole, and a compression spring is arranged between the square shaft head and the square hole. The film supporting frame 6 is connected to the bottom end of the movable shaft 102; as Figure 6 shown, the lever 11 includes a collar 111, a connecting rod 112, and a rolling part 113. The rolling part 113 and the collar 111 are respectively located at both ends of the connecting rod 112, as Figure 7As shown, the collar 111 is sleeved on the movable shaft 102. One side of the collar 111 is fixed by a shaft shoulder, and the other side is fixed by a snap ring 17. The cam assembly 12 includes a cam 121 and a second servo 122 for driving the cam 121 to rotate. A cam groove 123 is provided on the outer surface of the cam 121. The rolling part 113 is embedded in the cam groove 123, and the rolling part 113 can roll along the cam groove 123 when the cam 121 rotates.

[0045] As another preferred embodiment, temperature sensors are provided on both the cold plate 2 and the hot plate 3 to detect the temperatures of the cold plate 2 and the hot plate 3, so as to regulate the temperature gradient between the cold plate 2 and the hot plate 3, regulate the landing positions of nanoparticles with different particle sizes, and enable particulate matters in different particle size ranges to fall onto different sample membranes.

[0046] As another preferred embodiment, as Figure 2 and Figure 3 shown, both the collector and the collector are placed in the box 13, and the air pump 5 and the air inlet 4 of the collector are both located outside the box 13. As a more preferred method, a fan is also provided in the box 13 to dissipate heat inside the box 13.

[0047] In order to collect nanoparticles in the target range more accurately, this embodiment also provides a collection method using the above-mentioned nanoparticle collection device with particle size resolution, which is specifically as follows:

[0048] There are two cases to consider for the particulate matter following the gas to obtain the thermophoretic velocity between the cold plate 2 and the hot plate 3. For the particle size of the particulate matter When (λ is the mean free path of gas molecules, for air under standard pressure, λ is 66 nm), the thermophoretic velocity is independent of the particle size of the particulate matter and is proportional to the temperature gradient. The thermophoretic velocity generated is:

[0049] , Equation 1, where T is the ambient temperature, T is the temperature gradient, is the viscosity of the gas, is the gas density. The "-" sign in the formula represents the direction of the thermophoretic velocity, and the "-" sign indicates that the direction of the thermophoretic velocity is from the hot plate 3 to the cold plate 2.

[0050] For In this case, a temperature gradient is established inside the particulate matter, which affects the temperature of the surrounding gas and thus also affects the temperature gradient near the particulate matter. This effect depends on the particle size of the particulate matter and the thermal conductivity of the surrounding gas and the thermal conductivity of the particulate matter Ratio, so the coefficient H is introduced: , Equation 2, where is determined according to the chemical components of atmospheric particulate matter. In addition, when the particle size is close to the molecular mean free path, the Sinclair slip effect needs to be considered, and the correction factor is introduced: , Equation 3, where , , , so, for the thermophoretic velocity of the particles is: Equation 4, the thermophoretic velocity of the particles decreases with the increase of the particle size.

[0051] When the distance a between the cold plate 2 and the hot plate 3 is fixed, a ℃ / mm temperature gradient is created between the cold plate 2 and the hot plate 3, The value range of is 1 to 2. When , according to Equation 1, the maximum thermophoretic velocity of the particles entering the collection chamber is calculated. According to , the shortest time for the particles to hit the cold plate 2 can be known. When the velocity of the particles entering the collection chamber is fixed, the shortest horizontal movement distance is . By setting the first sample film at this distance, the particles with particle size can be collected; for the particles with particle size , according to Equation 4, as the particle size increases, the obtained thermophoretic velocity decreases, and the time to hit the cold plate 2 increases, resulting in an increase in the horizontal movement distance, and the particles hit the subsequent sample films. Therefore, on the basis of determining the position of the first sample film, multiple sample films are continuously arranged along the gas flow direction, and the collection of nano-particles with different particle sizes can be realized.

[0052] As another embodiment, the collection of nano-particles in different particle size ranges can also be regulated by controlling the temperature gradient and gas flow rate between the cold plate 2 and the hot plate 3.

[0053] In order to precisely control the air flow rate entering the device, a regulating valve for regulating the intake air flow rate is installed at the intake port of the air pump 5. As a preferred method, this regulating valve can be a needle valve or a solenoid valve. Two temperature sensors are respectively installed on the cold plate 2 and the hot plate 3, and provide the real-time monitored temperature to the PID controller. The controller is connected to the refrigeration component of the cold plate 2 and the heating component of the hot plate 3 to adjust the temperatures of the cold plate 2 and the hot plate 3 according to the set target temperature gradient. The regulating valve can also be connected to the controller to achieve automatic regulation of the intake air volume.

[0054] As Figure 2 and Figure 3 shown, a size-resolved nano-particle collection device includes a box body 13, an air pump 5, a zero filter, a fan, a collector, and a sampler. Among them, the air pump 5 and the zero filter are arranged at a position on the upper right side above the top cover of the box body 13. Two fans are arranged in the fan mounting holes on the rear side plate of the box body 13. The sampler is arranged on four positioning pins on the inner side of the bottom plate of the box body 13 through four positioning holes. The intake port 4 and the air outlet of the sampler are respectively arranged in the slot holes reserved on the left side plate and the right side plate of the box body 13. The intake port 4 communicates directly with the outside, and the air outlet is connected to the zero filter. The zero filter is used to prevent particles from entering the air pump 5, and then is connected to the air pump 5. A needle valve is provided at the intake port of the air pump 5. The collector is arranged in the shaft hole of the top cover of the box body 13 through the fixing shaft 101 at the upper part. The first servo 103 is arranged above the top cover of the box body 13 and is connected to the fixing shaft 101. The two film support platforms 7 on the film support frame 6 are arranged directly above the collection holes 8 and the protection cavity 9 on the cold plate protection plate.

[0055] A handle is provided on the left side above the top cover of the box body 13, and the top cover of the box body 13 is installed on the upper end of the right side plate through a pin shaft, so that the collector can be removed from the box body 13. A visible window with plexiglass installed is provided on the front side plate of the box body 13. Two fan mounting holes are symmetrically provided on the rear side plate of the box body 13. Four positioning pins are symmetrically arranged on the inner side of the bottom plate of the box body 13, and compression springs are provided on the positioning pins.

[0056] The collection method of the above collection device in this embodiment is as follows: In this embodiment, the sample film for collecting nanoparticles is arranged on the bottom surface of the film support plate 15. The sample film and the bottom surface of the film support plate 15 can be bonded or clamped. During operation, the second servo motor 122 is started to rotate the cam 121 by 180°. The lever 11 drives the movable shaft 102 to push the film support 6 downward, so that the film support table 7 enters the collection hole 8, and the film support plate 15 is closely attached to the cold plate 2 on the collector. The air pump 5 is started, and the gas enters the collection chamber through the air inlet 4 and collects nanoparticles of different particle sizes through the sample film. After one collection is completed, the second servo motor 122 is started to rotate 180°. The film support 6 is lifted, driving the film support table 7 to disengage from the collector. The first servo motor 103 drives the film support table 7 to rotate 180°. The two film support tables 7 exchange positions. The second servo motor 122 is started again to rotate 180°, driving the sample film support 6 downward, so that the second film support table 7 enters the collection hole 8. At the same time, the film support table 7 that has completed the first collection enters the protection chamber 9 to prevent air pollution of the collected sample film. The temperature gradient between the cold plate 2 and the hot plate 3 or the flow rate of the air pump 5 is reset for the second collection. After the collection is completed, the second servo motor 122 is started again to rotate 180°. The film support 6 is lifted, driving the film support table 7 to disengage from the collection hole 8. The air pump 5 is turned off, and the handle on the top cover of the box body 13 is lifted to take out the collector, and the sample film is removed to complete the entire collection process.

[0057] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made in these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A nanoparticle collection device with particle size resolution, characterized in that: include: A collector, comprising a collector body (1), a cold electrode plate (2) and a hot electrode plate (3), wherein a collection chamber is provided in the collector body (1), the cold electrode plate (2) is arranged at the top of the collection chamber, and the hot electrode plate (3) is arranged at the bottom of the collection chamber, the collection chamber has an air inlet (4) connected to the atmosphere, and the outlet of the collection chamber is connected to an air pump (5); A collector comprises a film support frame (6), two film support tables (7) and a film support frame driving unit, wherein the two film support tables (7) are both arranged at the bottom end of the film support frame (6), the film support tables (7) are used to carry a sample film, and the sample film is located at the bottom of the film support tables (7); the collector body (1) is provided with a collecting hole (8) extending from the top of the collector body (1) to the inside of the collecting cavity, the collector body (1) is also provided with a protective cavity (9), the two film support tables (7) are respectively located in the collecting hole (8) and the protective cavity (9), and the film support frame driving unit is used to enable the two film support tables (7) in the collecting hole (8) and the protective cavity (9) to complete the position exchange.

2. The nanoparticle collection device for particle size resolution according to claim 1, characterized in that: At least one semiconductor cooling sheet (14) is arranged in the film supporting platform (7), a film supporting plate (15) made of the same material as the cold electrode plate (2) is arranged at the bottom of the film supporting platform (7), the sample film is located at the bottom of the film supporting plate (15), the semiconductor cooling sheet (14) is used to provide cooling to the film supporting plate (15), and a radiator (16) is arranged on the film supporting platform (7) for dissipating heat and cooling the semiconductor cooling sheet (14).

3. The nanoparticle collection device for particle size resolution according to claim 1, characterized in that: The film support frame driving unit comprises: The transmission shaft (10) comprises a vertically arranged fixed shaft (101), a movable shaft (102) and a first steering gear (103); the top of the fixed shaft (101) is fixedly connected to the first steering gear (103); the bottom of the fixed shaft (101) is provided with a square hole along the axial direction; the top of the movable shaft (102) is a square shaft head, the square shaft head is located in the square hole, and a compression spring is provided between the square shaft head and the square hole; the film support frame (6) is connected to the bottom end of the movable shaft (102); A lever (11) comprising a collar (111), a connecting rod (112) and a rolling portion (113), wherein the rolling portion (113) and the collar (111) are respectively located at two ends of the connecting rod (112), the collar (111) is sleeved on the movable shaft (102), and one side of the collar (111) is fixed by a shaft shoulder, and the other side is fixed by a retaining spring (17); A cam assembly (12) comprises a cam (121) and a second servo (122) for driving the cam (121) to rotate, wherein a cam groove (123) is provided on the outer surface of the cam (121), a rolling portion (113) is embedded in the cam groove (123), and the rolling portion (113) can roll along the cam groove (123) when the cam (121) rotates.

4. The nanoparticle collection device for particle size resolution according to claim 1, characterized in that: The cold pole plate (2) and the hot pole plate (3) are both provided with temperature sensors.

5. The nanoparticle collection device for particle size resolution according to claim 1, characterized in that: A regulating valve for regulating the intake air flow rate is installed at the air inlet of the air pump (5).

6. The nanoparticle collection device for particle size resolution according to claim 1, characterized in that: A sealing ring is provided on the outer periphery of the film supporting platform (7) or the inner wall of the collecting hole (8) and the protective cavity (9).

7. The collection method of the nanoparticle collection device with particle size resolution as claimed in claim 1, characterized in that: The following steps are involved: When the particle size of the particles to be collected is When , the thermophoresis velocity of nanoparticles is: , where λ is the mean free path of gas molecules; T is the ambient temperature, T is the temperature gradient, is the viscosity of the gas, is the gas density; When the particle size of the particles to be collected is When , the thermophoresis velocity of nanoparticles is: ; where H is the coefficient, is the correction factor; When the distance between the cold pole plate (2) and the hot pole plate (3) is determined, a gap is created between the cold pole plate (2) and the hot pole plate (3). Temperature gradient in °C / mm, The value range is 1~ 2. When When the time of entering the collection cavity is calculated The maximum thermophoretic velocity of nanoparticles ,according to , and the shortest time for the nanoparticles to hit the cold plate (2) is obtained , where a is the distance between the two plates; when the nanoparticles entering the collection chamber have a speed of At a certain time, the shortest distance that particles move horizontally between the cold plate (2) and the hot plate (3) is , at the shortest distance Set the first sample membrane to collect the particle size of particulate matter; For particle size The particles will hit the sample membrane behind the first sample membrane, realizing the collection of particles of different sizes.

8. The collection method of the nanoparticle collection device with particle size resolution according to claim 7, characterized in that: The correction factor : ,in , , , is the particle size of the particles.

9. The collection method of the nanoparticle collection device with particle size resolution according to claim 7, characterized in that: Definition of coefficient H: ,in is the thermal conductivity of the particles, is the thermal conductivity of the surrounding gas, is the particle size of the particles.

Images