An automatic microplastic collecting device and method for water body

Abstract

The application discloses a kind of water body micro plastic automatic sheet collecting device and method, belong to water conservancy research equipment technical field.The device mainly includes cover, sample inlet water tank, digestion tank, storage tank, microfluidic optical identification system, multi-pass flow valve, diversion collection plate, piece table and controller;Water sample is sent into digestion tank after being coarsely filtered by sample inlet water tank to complete organic matter digestion, then enters microfluidic optical identification system, imaging is formed to droplet by means of CCD array and LED light source, whether micro plastic is contained in droplet is judged by controller through image recognition, and droplet sorting is realized by controlling multi-pass flow valve;Micro plastic-containing droplet is transported to the diversion collection plate with heating function, and after rapid evaporation of droplet, micro plastic particles directly fall on substrate to complete sheet collecting.The application realizes water sample pretreatment-identification-sorting-sheet collecting automation, reduces sample loss caused by manual operation, can be adapted to various analysis substrates, and is convenient for water body micro plastic standardization monitoring.

Description

Technical Field

[0001] This invention relates to the field of water conservancy scientific research equipment manufacturing, and in particular to an automatic collection device and method for microplastics in water. Background Technology

[0002] Microplastics refer to plastic fragments, fibers, or particles with a diameter of less than 5 millimeters. They are products of the weathering, breakage, and pyrolysis of plasticized products. Microplastics in water bodies are dispersed in oceans, rivers, lakes, and drinking water sources. With their large specific surface area and strong hydrophobicity, they readily adsorb heavy metals, persistent organic pollutants, and toxic substances such as antibiotics, forming complex pollution carriers. Simultaneously, the plasticizers, flame retardants, and other additives they contain are slowly released, and some degradation products have endocrine-disrupting toxicity. Microplastic pollutants in water bodies can be transferred along the food chain through ingestion by plankton and accidental ingestion by fish, ultimately reaching humans through drinking water or seafood, posing a potential threat to human health. Systematic investigations into the occurrence, source apportionment, and ecological risk assessment of microplastic pollution in water bodies have become an important frontier topic in environmental science.

[0003] The concentration of microplastics in natural water bodies is usually extremely low. In clean waters, the content of microplastics is often at the trace level of tens to hundreds of particles per liter. Water samples also contain a large amount of organic matter, suspended particles and other interfering substances. Water samples need to undergo multiple pretreatment steps such as sampling, filtration, digestion and density separation before the target substances that can be analyzed can be obtained.

[0004] The process of transferring and fixing microplastic targets onto a solid substrate that can be analyzed by a microscope, infrared spectrometer, or Raman spectrometer is called microplastic "slab collection." Slab collection is a necessary step for conducting microplastic morphology observation, chemical identification, and physical property analysis. Existing methods for collecting microplastics in water bodies can be mainly divided into three categories: The first category is the manual pipetting and droplet coating method, which relies on a pipette to add concentrated suspension droplets to the substrate surface and then dry them. The operation is simple, but uneven droplet spreading can cause particle agglomeration. During the drying process, the solute ring effect can cause a large number of particles to accumulate at the edge of the droplets, which destroys the random representativeness of the observation results. The second category is the negative pressure filtration and retention method, which relies on the filter membrane to retain microplastics and then attach the filter membrane to the substrate. The collection efficiency is relatively high, but microplastics are easy to embed into the pores of the filter membrane, which is not conducive to clear in-situ observation. The membrane-sheet bonding interface generates optical scattering, which interferes with the spectral signal. The third category is the centrifugal deposition method, which relies on centrifugal force to make the particles settle to the substrate surface. This method is effective for high-density plastic particles, but the settling efficiency is very low for common microplastics with densities close to water, such as polyethylene and polypropylene. Improper control of centrifugal force can also cause particle deformation.

[0005] In addition, existing microplastic collection methods are all open-access manual operations. The original concentration of microplastics in the water is low, and the absolute number of samples after pretreatment is limited. The multiple processes of pipetting, transferring, attaching, and settling cause secondary loss of microplastics and residues adhering to the surface of the components, further reducing the number of microplastic particles in the effective observation area of ​​the substrate, reducing the reliability of statistical analysis, and making it difficult to compare the results of sample preparation from different experimental batches. The combination of low sample concentration and low collection efficiency results in long microplastic collection operations, high labor costs, and low success rates, hindering the transition of water microplastic monitoring from laboratory research to standardized operational practice. Summary of the Invention

[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide an automatic microplastic collection device and method for water bodies, which solves the technical problems of traditional microplastic collection relying on manual labor, cumbersome operation, low efficiency, and serious loss of low-concentration samples, and realizes the automated process of water sample pretreatment-particle identification-sorting-collection.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: An automatic microplastic collection device for water includes a casing, a sample inlet tank, a digestion tank, a storage tank, a microfluidic optical recognition system, a multi-way diverter valve, a flow guide plate, a substrate holder, a waste liquid tank, and a controller. The bottom of the filter side of the sample inlet tank is connected to the digestion tank, the storage tank, and the microfluidic optical recognition system sequentially via pipes. The microfluidic optical recognition system includes a transparent pipe and a microscope camera. The upper end of the transparent pipe is connected to the bottom of the storage tank, and the microscope camera is positioned close to the transparent pipe. The lower end of the transparent pipe is connected to the multi-way diverter valve. The first outlet of the multi-way diverter valve is connected to the waste liquid tank, and the outlet pipe of the second outlet is suspended above the flow guide plate. The flow guide plate is supported by an electric cylinder, which adjusts the pitch angle of the flow guide plate by extension and retraction. The substrate holder is located at the bottom of the device and is used to place substrates. The substrate holder is connected to the outlet of the flow guide plate. The controller is electrically connected to the microfluidic optical recognition system, the multi-way diverter valve, and the electric cylinder, and is also equipped with an LCD control panel.

[0008] Furthermore, inspection doors are provided on both the upper and lower layers of the outer casing, the sample inlet tank is equipped with a tank cover, and a coarse filter screen is installed inside the sample inlet tank; a second solenoid valve is installed on the connecting pipe between the sample inlet tank and the digestion tank.

[0009] Furthermore, the microfluidic optical recognition system also includes an LED light source, and the microscopic imaging device is an optical microscopic imaging CCD array; the optical microscopic imaging CCD array and the LED light source are respectively located on both sides of the transparent pipe; the transparent pipe has a multi-channel parallel structure; a first solenoid valve is installed on the pipeline between the storage tank and the transparent pipe, and the first solenoid valve is electrically connected to the output terminal of the controller.

[0010] Furthermore, droplet channels that are wider at the top and narrower at the bottom are opened on the surface of the flow guide and collection plate.

[0011] Furthermore, the front of the flow collection plate is coated with a superhydrophobic coating.

[0012] Furthermore, a heating resistance wire is arranged on the back of the flow guide and collection plate, the heating resistance wire is connected to a heating electrode, and the heating electrode is electrically connected to the controller.

[0013] Furthermore, the substrate support stage has grooves that are adapted to the size of a standard substrate, and these grooves are used to position and fix the substrate.

[0014] Furthermore, the sample inlet tank, digestion tank, and storage tank are all equipped with hatch covers, and each tank is equipped with a gas guide pipe, which connects each tank to the outside atmosphere.

[0015] Furthermore, the transparent pipe is a transparent glass pipe.

[0016] An automated method for collecting microplastics in water includes the following steps: S1: Pour the water sample to be tested into the side of the sample inlet tank where the coarse filter is set. The water sample completes the primary filtration by passing through the coarse filter. S2: Add digesting agent into the digestion tank to prepare for organic matter digestion treatment of the water sample after primary filtration; S3: Select a substrate suitable for subsequent testing, and insert the substrate into the groove of the substrate holder to complete the positioning and fixation; S4: Connect the device power supply and complete the setting of operating parameters through the LCD control panel. The setting parameters include the opening and closing parameters of the second solenoid valve, the single output droplet volume of the first solenoid valve, the pitch angle of the guide collection plate, and the heating temperature of the guide collection plate. S5: Start the device and the water sample enters the microfluidic optical recognition system after completing the initial filtration, digestion and storage in sequence. The controller identifies the microplastic particles in the droplets and controls the multi-way diverter valve to sort the droplets. The droplets containing microplastics are guided to the flow guide and collection plate, where they evaporate. The microplastic particles fall onto the substrate to complete the collection. After the device finishes running, disconnect the power and remove the substrate that carries the microplastic particles.

[0017] The beneficial effects of this invention are: First, the entire device automates the entire process of water sample initial filtration, digestion, optical identification, droplet sorting, and collection. The water sample enters the transparent pipe in droplet form under the control of the first solenoid valve. The optical microscopic camera CCD array provides real-time imaging, and the machine learning algorithm identifies the microplastics inside the droplets. The multi-way diversion valve completes the sorting, and the droplets carrying microplastics are transported to the heated guide collection plate for rapid evaporation. The microplastic particles fall directly onto the substrate, avoiding particle loss caused by manual sample transfer.

[0018] Second, the device acquires raw image data from the optical microscopic imaging CCD array, and the host can statistically obtain information such as the quantity, particle size, and color of microplastics collected on the substrate, realizing synchronous data statistics across the entire substrate.

[0019] Third, the device collects microplastics by physical trapping. The grooves of the substrate stage can be adapted to various general-purpose substrates such as glass slides, silicon wafers, and carbon mesh, and can be adapted to various subsequent characterization methods such as Raman, infrared, and TEM. The amount of microplastics enriched on the substrate can be adjusted by controlling the running time of the device. Attached Figure Description

[0020] The invention will be further described below with reference to the accompanying drawings: The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0021] Figure 1 This is a schematic diagram of the overall structure of the present invention; Figure 2 This is a schematic diagram of the cross-sectional structure of the present invention; Figure 3 This is a schematic diagram of the microfluidic optical recognition system of the present invention; Figure 4 This is a schematic diagram of the microplastic sorting and collecting sheet component of the present invention; Figure 5 This is a schematic diagram of the front of the flow guide and collection plate; Figure 6 This is a schematic diagram of the back of the flow guide and collection plate; Figure 7 This is a schematic diagram of the digestion vessel structure; Figure 8 This is a schematic diagram showing the connection relationship of the various electrical components in this invention. Figure 9 This is a flowchart of the present invention.

[0022] Explanation of reference numerals in the attached drawings: 1. Cover, 2. Sample inlet tank, 3. Tank cover, 4. Coarse filter screen, 5. Tank support, 6. Digestion tank, 7. Storage tank, 8. Power cord, 9. Transparent pipe, 10. Optical microscopic imaging CCD array, 11. LED light source, 12. First solenoid valve, 13. Multi-way diverter valve, 14. First outlet, 15. Second outlet, 16. Waste liquid tank, 17. Electric cylinder, 18. Electric cylinder cable, 19. Guide collection plate, 20. Droplet channel, 21. Superhydrophobic coating, 22. Heating resistance wire, 23. Heating electrode, 24. Plate support, 25. Groove, 26. Substrate, 27. Controller, 28. LCD control panel, 29. Second solenoid valve, 30. Pipe, 31. Inspection door, 32. Casters, 33. Tank cover, 34. Gas duct, 35. Signal control line, 36. Droplet. Detailed Implementation

[0023] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0024] like Figures 1 to 8 As shown, an automatic microplastic collection device for water includes a housing 1, a sample inlet tank 2, a digestion tank 6, a storage tank 7, a microfluidic optical recognition system, a multi-way diverter valve 13, a flow guide and collection plate 19, a plate receiving platform 24, a waste liquid tank 16, and a controller 27. The bottom of the filter side of the sample inlet tank 2 is connected sequentially to the digestion tank 6, the storage tank 7, and the microfluidic optical recognition system via a pipe 30, allowing the water sample to flow sequentially along the pipe. The bottom of the storage tank 7 is connected to the microfluidic optical recognition system, enabling the downward transport of pre-treated water samples. The microfluidic optical recognition system includes a transparent pipe 9 and a microscope imaging device 10. The transparent pipe 9 is a transparent glass pipe, with its upper end connected to the bottom outlet of the storage tank 7. The microscope imaging device 10 is arranged close to the outer wall of the transparent pipe 9 to image and collect droplets flowing inside the pipe. The lower end of the transparent pipe 9 is connected to a multi-way diverter valve 13. The multi-way diverter valve 13 is a LabSmith AV202-C360 high-speed two-position four-way microfluidic switching valve, enabling rapid two-way droplet sorting with no dead volume, suitable for microfluidic droplet sorting conditions. The multi-way diverter valve 13 has a first outlet 14 and a second outlet 15. The first outlet 14 is connected to a waste liquid tank 16, guiding droplets without microplastics after identification into the waste liquid tank for discharge. The second outlet 15 is suspended above the flow guide and collection plate 19, transporting droplets containing microplastic particles to the flow guide and collection plate 19. The flow guide and collection plate 19 is supported by an electric cylinder 17, which drives a push rod to extend and retract, thereby adjusting the pitch angle of the flow guide and collection plate 19. The electric cylinder 17 is a Huiling Technology Z-Mod-EP-35RS-50 micro servo electric cylinder. The substrate support stage 24 is located at the bottom of the device and is used to place the substrate 26. The substrate support stage 24 is connected to the discharge port of the flow guide and collection plate 19, and the microplastic particles sliding down from the flow guide and collection plate 19 can directly reach the substrate 26. The controller 27 is electrically connected to the microfluidic optical recognition system, the multi-way diverter valve 13, and the electric cylinder 17. The controller 27 is also equipped with an LCD control panel 28. The operator can input various operating parameters through the LCD control panel 28. The controller 27 uses an industrial-grade ARM industrial control computer, equipped with a Linux system, and runs a machine learning inference model. The external LCD control panel (28) is an industrial touch screen display to realize human-machine interaction parameter input.

[0025] Furthermore, both the upper and lower layers of the outer casing 1 are equipped with inspection doors 31, allowing operators to disassemble and clean the tank, add reagents, and perform maintenance through these doors. The bottom of the casing 1 is fitted with casters 32 for easy transport of the entire unit to different test sites for water sample testing. The sample inlet tank 2 is equipped with a tank cover 3 to prevent external debris from falling into the water sample. A coarse filter 4 is installed inside the sample inlet tank 2 to intercept large impurities in the water sample, preventing large particles from entering the downstream pipeline and causing blockages. A second solenoid valve 29 is installed on the pipeline 30 connecting the sample inlet tank 2, digestion tank 6, and storage tank 7. The controller 27 outputs a signal to control the opening and closing of the second solenoid valve 29, realizing the start and stop of the water sample transport process. The second solenoid valve 29 is a Baode 6013 type two-way fluid solenoid valve, resistant to weak acids and alkalis, suitable for controlling the on / off flow of the water sample pipeline after digestion.

[0026] Furthermore, the microfluidic optical recognition system 8 is also equipped with an LED light source 11, and the microscopic imaging device is an optical microscopic imaging CCD array 10. The optical microscopic imaging CCD array 10 uses a Mingmei MS16H high-speed microscopic camera with USB 3.0 output and a maximum full resolution of 666fps, which is suitable for high-speed droplet imaging in microfluidic channels and can capture dynamic images of microplastic particles. The image data is transmitted to the controller 27 host for inference and recognition. The optical microscopic imaging CCD array 10 and the LED light source 11 are respectively located on both sides of the transparent pipe 9. The LED light source 11 provides backlight illumination to ensure the clarity of the images acquired by the optical microscopic imaging CCD array 10. The transparent pipe 9 has a multi-channel parallel structure, with multiple channels processing water samples simultaneously, increasing the total amount of water samples processed per unit time. A first solenoid valve 12 is installed on the upper part of the transparent pipe 9. The first solenoid valve 12 is electrically connected to the output terminal of the controller 27. The first solenoid valve 12 is controlled by the controller 27 to cut the water in the storage tank 7 into independent droplets of a set volume and release them downwards. The first solenoid valve 12 is a microdrop MJ-K-102-L micro-micro solenoid valve with a minimum liquid dispensing volume of 100nL and a response speed in milliseconds. It can cut the water in the storage tank into independent droplets of 10μL, which is suitable for the microdroplet generation requirements of this device.

[0027] Furthermore, the surface of the flow-guiding and collecting plate 19 is provided with droplet channels 20 that are wider at the top and narrower at the bottom, guiding the droplets to flow along a preset path and preventing them from splashing everywhere. The front of the flow-guiding and collecting plate 19 is coated with a superhydrophobic coating 21 to reduce the adhesion between the droplets and the plate surface, reducing the amount of microplastic particles adhering to the surface of the flow-guiding and collecting plate 19 and causing sample loss. A heating resistance wire 22 is arranged on the back of the flow-guiding and collecting plate 19, which is connected to a heating electrode 23. The heating electrode 23 is electrically connected to a controller 27 and receives the output signal from the temperature control unit of the controller 27 to maintain a stable high temperature on the plate surface. The droplets evaporate rapidly upon contact with the high-temperature plate surface, leaving only microplastic solid particles. The push rod can drive the flow-guiding and collecting plate 19 to adjust the pitch angle arbitrarily within the range of 0~90°, adjusting the flow path of the droplets inside the channels so that the droplets reach the outlet position just in time to complete the evaporation of water.

[0028] Furthermore, the stage 24 has a groove 25 that is adapted to the size of the general substrate 26. The groove 25 is used to position and fix the substrate 26. The substrate 26 is embedded in the groove 25 and will not be displaced or shifted, ensuring that the microplastic particles can accurately fall into the observation area of ​​the substrate 26.

[0029] Furthermore, the sample inlet tank 2, digestion tank 6, and storage tank 7 are all equipped with hatch covers 33. When the hatch covers 33 are opened, digestion agents can be added and the inner walls of the tanks can be cleaned. Each tank is equipped with a gas guide pipe 34, which connects each tank to the outside atmosphere to eliminate negative pressure inside the tank and ensure that the water sample flows smoothly downward by gravity.

[0030] Furthermore, the controller 27 integrates the host, control power supply, solenoid valve control unit, multi-way diverter valve control unit, electric cylinder hydraulic control unit, and thermal resistance wire temperature control unit; the controller 27 receives real-time image signals from the optical microscope CCD array 10 through the signal control line 35; the controller 27 has a built-in machine learning algorithm module, which identifies whether the droplets flowing through the transparent pipe 9 contain microplastic particles based on the images collected by the optical microscope CCD array 10.

[0031] The detailed operation procedure for the automatic collection of microplastic sheets in water using the device in this embodiment is as follows: Figure 9 As shown: S1: Pour the water sample collected in the field into the sample inlet tank 2 and set up a coarse filter 4 on one side. The water sample passes through the coarse filter 4, and large solid debris is intercepted on the filter, completing the primary filtration of the water sample. S2: Open the hatch cover 33 of the digestion tank 6, add the digestion agent into the digestion tank 6. In this embodiment, potassium hydroxide is selected as the digestion agent. Close the hatch cover 33 and prepare to decompose the organic matter interfering substances in the water sample. S3: Select a substrate 26 with a suitable material according to the requirements of subsequent spectral and electron microscopy detection, and smoothly embed the substrate 26 into the groove 25 of the substrate stage 24. The groove 25 limits and fixes the substrate 26 to prevent displacement during the collection process. S4: Connect the power supply to the whole machine. The operator uses the LCD control panel 28 to input the operating parameters of the whole device, set the opening and closing sequence of the second solenoid valves 29 of each pipeline, set the single output droplet volume of the first solenoid valve 12 to 10 microliters, set the pitch angle of the flow guide and collection plate 19, and set the target heating temperature of the heating resistance wire 22. In this embodiment, the second solenoid valve 29 is preferably set to normally open, the single output flow rate of the first solenoid valve 12 is set to 10 microliters, the angle between the flow guide and collection plate 19 and the vertical line is set to 70° (i.e., the angle between the flow guide and collection plate 19 and the horizontal plane is 20°), and the constant temperature of the flow guide and collection plate 19 is set to 200°. This temperature is an exemplary parameter and can be adjusted according to the heat resistance performance of the substrate used to avoid damage to the substrate due to heat.

[0032] S5: After parameter confirmation, the entire machine is started. The water sample after primary filtration enters the digestion tank 6 through pipe 30. Inside the digestion tank 6, the digesting agent decomposes the organic matter in the water sample. After digestion, the water sample flows into the storage tank 7 for temporary storage. Under the control of the first solenoid valve 12, the water sample in the storage tank 7 is quantitatively dripped into the transparent pipe 9. The LED light source 11 illuminates the droplet, and the optical microscopic camera CCD array 10 acquires droplet images in real time. The images are transmitted back to the controller 27, and the machine learning algorithm identifies whether the droplet contains microplastics. For droplets that do not contain microplastics, the multi-way diversion valve 13 switches to the first outlet 14, and the droplet is discharged into the waste liquid tank 16. Upon receiving droplets containing microplastic particles, the multi-way diverter valve 13 switches to the second outlet 15, and the droplets fall onto the guide collection plate 19. The droplets flow along the droplet channel 20, and the water evaporates rapidly under the action of the high-temperature plate surface. The microplastic solid particles fall onto the surface of the substrate 26 through the outlet of the guide collection plate 19. The entire device continuously cycles through the water sample delivery-identification-sorting-collection process. After reaching the preset running time, the device automatically stops. The operator cuts off the power, opens the cover inspection door 31 or directly removes the substrate stage 24, and takes out the substrate 26 enriched with microplastic particles, which can then be used for subsequent microscopic observation and spectroscopic identification experiments.

[0033] The embodiments described in this specification are merely examples of implementations of the inventive concept. The scope of protection of this invention should not be considered as limited to the specific forms stated in the embodiments. The scope of protection of this invention also extends to equivalent technical means that can be conceived by those skilled in the art based on the inventive concept.

Claims

1. An automatic collection device for microplastics in water, characterized in that, It includes a housing (1), a sample inlet tank (2), a digestion vessel (6), a storage tank (7), a microfluidic optical recognition system, a multi-way diverter valve (13), a flow guide and collection plate (19), a substrate holder (24), a waste liquid tank (16), and a controller (27); The bottom of the filter side of the sample inlet tank (2) is connected in sequence to the digestion tank (6), the storage tank (7) and the microfluidic optical recognition system via pipes; The microfluidic optical recognition system includes a transparent pipe (9) and a microscopic camera (10). The upper end of the transparent pipe (9) is connected to the bottom of the storage tank (7), and the microscopic camera (10) is arranged close to the transparent pipe (9). The lower end of the transparent pipe (9) is connected to the multi-way diverter valve (13); the first outlet (14) of the multi-way diverter valve (13) is connected to the waste liquid tank (16), and the outlet pipe of the second outlet (15) is suspended above the flow guide collection plate (19). The flow guide and collection plate (19) is supported by an electric cylinder (17), and the electric cylinder (17) adjusts the pitch angle of the flow guide and collection plate (19) by extending and retracting. The substrate support platform (24) is located at the bottom of the device and is used to place the substrate (26). The substrate support platform (24) is connected to the outlet of the flow guide and collection plate (19). The controller (27) is electrically connected to the microfluidic optical recognition system, the multi-way diverter valve (13), and the electric cylinder (17). The controller (27) is also equipped with an LCD control panel (28).

2. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, The outer shell (1) is equipped with inspection doors (31) on both the upper and lower layers. The sample inlet tank (2) is equipped with a tank cover (3). A coarse filter screen (4) is installed inside the sample inlet tank (2). A second solenoid valve (29) is installed on the connecting pipe between the sample inlet tank (2) and the digestion tank (6).

3. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, The microfluidic optical recognition system also includes an LED light source (11), and the microscopic imaging device is an optical microscopic imaging CCD array (10); the optical microscopic imaging CCD array (10) and the LED light source (11) are respectively located on both sides of the transparent pipe (9); the transparent pipe (9) has a multi-channel parallel structure; a first solenoid valve (12) is installed on the pipeline between the storage tank (7) and the transparent pipe (9), and the first solenoid valve (12) is electrically connected to the output terminal of the controller (27).

4. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, The surface of the flow guide and collection plate (19) has droplet channels (20) that are wider at the top and narrower at the bottom.

5. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, The flow collection plate (19) is coated with a superhydrophobic coating (21) on its front side.

6. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, A heating resistance wire (22) is arranged on the back of the flow collection plate (19). The heating resistance wire (22) is connected to the heating electrode (23). The heating electrode (23) is electrically connected to the controller (27).

7. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, The substrate stage (24) has a groove (25) that is adapted to the size of the general substrate (26). The groove (25) is used to position and fix the substrate (26).

8. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, The sample inlet tank (2), digestion tank (6), and storage tank (7) are all equipped with hatch covers (33), and each tank is equipped with a gas guide pipe (34), which connects the tank to the outside atmosphere.

9. The automatic microplastic collection device for water bodies according to claim 1, characterized in that, The transparent pipe (9) is a transparent glass pipe.

10. A method for an automatic collection device for microplastics in water as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Pour the water sample to be tested into the sample inlet tank (2) and set one side of the coarse filter (4). The water sample passes through the coarse filter (4) to complete the primary filtration. S2: Add digesting agent into digestion tank (6) to prepare for organic matter digestion treatment of water sample after primary filtration; S3: Select a substrate (26) suitable for subsequent testing, and insert the substrate (26) into the groove (25) of the substrate holder (24) to complete the positioning and fixation; S4: Connect the device power supply and complete the operation parameter setting through the LCD control panel (28). The setting parameters include the opening and closing parameters of the second solenoid valve (29), the single output droplet volume of the first solenoid valve (12), the pitch angle of the guide collection plate (19), and the heating temperature of the guide collection plate (19). S5: Start the device and the water sample enters the microfluidic optical recognition system after completing the initial filtration, digestion and storage in sequence. The controller (27) identifies the microplastic particles in the droplets and controls the multi-way diverter valve (13) to sort the droplets. The droplets containing microplastics are guided to the flow collection plate (19). The droplets evaporate on the flow collection plate (19) and the microplastic particles fall onto the substrate (26) to complete the collection. After the device finishes running, cut off the power and take out the substrate (26) that carries the microplastic particles.

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