Microfluidic device and system for pretreatment of micro-plastic particles and treatment method

Abstract

According to the micro-fluidic device, system and treatment method for pretreatment of the micro-plastic particles, the micro-fluidic device provided by the invention can be used for pretreating plastic particles in a large-size range in an environment, and filtering, enrichment, digestion and recovery of the micro-plastic particles in the environment are realized, so that the treatment efficiency of micro-plastic in an environmental sample is improved. Moreover, the device is integrated with a detection device suitable for Raman spectrum detection, the treated sample can be directly used for Raman spectrum detection, the manual pretreatment operation process is greatly simplified, and the use of a digestion solution is reduced, so that an efficient, accurate and convenient pretreatment tool is provided for outdoor convenient monitoring of micro-plastics.

Description

Technical Field

[0001] This invention relates to the field of microplastic particle pretreatment and detection technology, and in particular to a microfluidic device, system and method for microplastic particle pretreatment. Background Technology

[0002] In recent years, microplastics, as a global environmental pollutant, have become an important issue in research and environmental protection. Microplastics refer to plastic particles with a diameter of less than 5 mm, mainly originating from the degradation of plastic products, industrial activities, and particles in personal care products. The widespread distribution of microplastics has been found in water bodies, soil, atmosphere, and living organisms, and they have been identified as posing potential threats to ecosystems and human health.

[0003] With the increasing severity of microplastic pollution, efficient and accurate detection and identification of microplastics has become a crucial issue in environmental monitoring. Currently, commonly used microplastic detection methods include microscopy, spectroscopic techniques (such as Fourier transform infrared spectroscopy and Raman spectroscopy), and mass spectrometry. Compared to infrared spectroscopy, Raman spectroscopy, as a non-destructive analytical technique, has been widely applied to the detection and analysis of microplastics due to its high spatial resolution, rapid response, and sensitivity to various plastic materials. Raman spectroscopy allows for the identification of different types of plastics and the acquisition of characteristic information about their molecular structures, thus enabling efficient qualitative and quantitative analysis of microplastics in the environment. However, in practical applications, Raman spectroscopy still faces challenges in detecting microplastics in environmental samples. For example, the concentration of microplastics in actual water bodies, especially oceans, is low, and the particle size varies considerably, requiring digestion to eliminate interference from biomass signals. Therefore, before detecting microplastics in the marine environment, pretreatment such as filtration, enrichment, and digestion is necessary. These pretreatments often consume significant amounts of time, and digestion consumes large quantities of chemical reagents. This undoubtedly increases both the economic and time costs for rapid microplastic detection.

[0004] To address these challenges, microfluidic technology has gradually become an important means of improving the efficiency of microplastic detection. Microfluidic devices can perform efficient pretreatment processes such as separation, enrichment, and purification of samples within tiny chambers, greatly reducing the required reagent volume and lowering detection costs. Furthermore, they are easy to operate and require minimal manual intervention. Currently, while existing microfluidic devices have some applications in microplastic pretreatment, they still have certain shortcomings in terms of integration, processing efficiency, and ease of operation. Especially when handling large-scale sample variations, existing chip devices still need optimization, and current microfluidic devices do not yet include the treatment of environmental plastic digestion. Summary of the Invention

[0005] Therefore, in response to at least one of the above problems, the present invention provides a microfluidic device, system, and method for pretreatment of microplastic particles.

[0006] This invention is implemented using the following scheme: This invention proposes a microfluidic device for pretreatment of microplastic particles, comprising a support structure, within which a closed chamber is provided. A first filter structure and a second filter structure are also supported side-by-side within the support structure. The pore size of the first filter structure is larger than that of the second filter structure. The first and second filter structures divide the chamber along its height into an upper chamber, a middle chamber, and a lower chamber. The support structure also has a first hole, a second hole, and a third hole, all extending from the outer surface of the support structure into the interior of the support structure. The first hole connects to the upper chamber via a first channel structure, the second hole connects to the middle chamber via a second channel structure, and the third hole connects to the lower chamber via a third channel structure.

[0007] In one embodiment, the third hole is used to introduce the liquid to be tested or the digestion solution; the second hole serves as a backflushing liquid inlet for introducing backflushing liquid.

[0008] In one embodiment, the first filter structure is a 10μm filter screen, and the second filter structure is a 1μm filter screen.

[0009] In one embodiment, the support structure is a layered structure, comprising, from top to bottom, a top layer, a first strip layer, a first support layer, a first flat sheet layer, a second strip layer, a second support layer, a second flat sheet layer, a third flat sheet layer, a third strip layer, and a bottom layer, with each layer tightly bonded to form the overall support structure; each of the first strip layer, the first support layer, the first flat sheet layer, the second strip layer, the second support layer, the second flat sheet layer, the third flat sheet layer, and the third strip layer contains sub-chambers, which combine to form the complete chamber; a second filter structure is disposed between the first support layer and the first flat sheet layer, and the first filter structure is disposed between the second flat sheet layer and the third flat sheet layer.

[0010] In one embodiment, the first hole penetrates downward from the top layer to the first strip layer, thereby forming a first sub-hole in each layer it passes through; the first strip layer is provided with a first channel structure, which connects the first sub-hole of the first strip layer with the sub-cavity.

[0011] In one embodiment, the second hole penetrates downward from the top layer to the second strip layer, thereby forming a second sub-hole in each layer it passes through; the second strip layer is provided with a second channel structure, which connects the second sub-hole of the second strip layer with the sub-cavity.

[0012] In one embodiment, the third hole penetrates downward from the top layer to the third strip layer, thereby forming a third sub-hole in each layer it passes through; the third strip layer is provided with a third channel structure, which connects the third sub-hole of the third strip layer with the sub-cavity.

[0013] In one embodiment, a first support structure is provided in the sub-cavity of the first support layer, and the first support structure is used to support the second filter structure; a second support structure is provided in the sub-cavity of the second support layer, and the second support structure can be used to support the first filter structure.

[0014] The present invention also proposes a microfluidic system for pretreatment of microplastic particles, including the microfluidic device as described above, and a detection device, wherein the detection device is made of high-purity aluminum plate and the surface of the detection device is provided with multiple detection grooves.

[0015] This invention also proposes a pretreatment method for microplastic particles, comprising the following steps: S1: Provide a microfluidic device as described in the preceding item; S2: Block the second hole of the microfluidic device using a blocking device, and introduce the test solution into the third hole, so that all the test particles are collected on the first filter structure and the second filter structure of the microfluidic device; S3: Pass the digestion solution into the third hole. After the digestion solution completely covers the first filter structure and the second filter structure, block the first hole and the second hole so that the microfluidic device is filled with digestion solution. S4: Remove the blocking device from the first hole and introduce sterile water into the third hole to wash away excess digestion solution and plastic particle digestion products; S5: Remove the blocking device from the second hole and move it to the first hole to block it. At the same time, invert the microfluidic device and introduce backflushing fluid into the second hole. Place the detection device under the third hole. The backflushing fluid flows through the second filter structure and the first filter structure in sequence, and flows out through the third hole into the detection groove of the detection device.

[0016] The technical solution provided by this invention has the following technical effects: This invention proposes a microfluidic device, system, and method for pretreatment of microplastic particles. The microfluidic device includes a support structure with a closed chamber within it. A first filter structure and a second filter structure are also supported side-by-side within the support structure. The first and second filter structures divide the chamber along its height into an upper chamber, a middle chamber, and a lower chamber. The support structure also has a first hole, a second hole, and a third hole. The first hole connects to the upper chamber via a first channel structure, the second hole connects to the middle chamber via a second channel structure, and the third hole connects to the lower chamber via a third channel structure. This microfluidic device can pretreat large-size plastic particles in the environment, achieving filtration, enrichment, disintegration, and recycling of microplastic particles, thereby improving the processing efficiency of microplastics in environmental samples. Furthermore, this invention integrates a detection device suitable for Raman spectroscopy detection, which can directly use the processed sample for Raman spectroscopy detection, greatly simplifying the manual pretreatment process and reducing the use of digestion solution, thus providing an efficient, accurate and convenient pretreatment tool for outdoor monitoring of microplastics. Attached Figure Description

[0017] Figure 1 This is a perspective view of the microfluidic device according to an embodiment of the present invention; Figure 2 This is an exploded view of the microfluidic device according to an embodiment of the present invention; Figure 3 This is a top view of the top layer of an embodiment of the present invention; Figure 4 This is a top view of the first strip layer in an embodiment of the present invention; Figure 5 This is a top view of the first support layer according to an embodiment of the present invention; Figure 6 This is a top view of the first flat sheet layer according to an embodiment of the present invention; Figure 7 This is a top view of the second strip layer according to an embodiment of the present invention; Figure 8 This is a top view of the second support layer according to an embodiment of the present invention; Figure 9 This is a top view of the second flat sheet layer according to an embodiment of the present invention; Figure 10 This is a top view of the third flat sheet layer according to an embodiment of the present invention; Figure 11 This is a top view of the third strip layer in an embodiment of the present invention; Figure 12 This is a top view of the bottom layer of an embodiment of the present invention; Figure 13 This is a flowchart of the microplastic particle pretreatment method according to an embodiment of the present invention. Detailed Implementation

[0018] To further illustrate the various embodiments, the present invention provides accompanying drawings. These drawings are part of the disclosure of the present invention, primarily used to illustrate the embodiments and to explain the operating principles of the embodiments in conjunction with the relevant descriptions in the specification. With reference to these drawings, those skilled in the art should be able to understand other possible implementations and the advantages of the present invention. Components in the drawings are not drawn to scale, and similar component symbols are generally used to represent similar components.

[0019] The present invention will now be further described in conjunction with the accompanying drawings and specific embodiments.

[0020] Example 1 like Figures 1-12 As shown, this embodiment provides a microfluidic system for pretreatment of microplastic particles, including a microfluidic device 1 and a detection device 7. The microfluidic device 1 has functions such as particle enrichment, digestion, cleaning, and backflushing. The microfluidic device 1 includes a support structure 2, within which a closed chamber 6 is provided. A first filter structure 30 and a second filter structure 40 are also supported side-by-side within the support structure 2. The first filter structure 30 and the second filter structure 40 divide the chamber 6 along its height direction into an upper chamber, a middle chamber, and a lower chamber.

[0021] The pore size of the first filter structure 30 is larger than that of the second filter structure 40, thus the particle size filtered by the first filter structure 30 is larger than that filtered by the second filter structure 40. For example, the first filter structure 30 is suitable for filtering particles with a particle size of 10 μm, and the second filter structure 40 is suitable for filtering particles with a particle size of 1 μm. In this embodiment, the first filter structure 30 and the second filter structure 40 are stainless steel filter screens.

[0022] The support structure 2 is also provided with a first hole 3, a second hole 4 and a third hole 5. The first hole 3, the second hole 4 and the third hole 5 all extend from the outer surface of the support structure 2 into the support structure 2. The first hole 3 is connected to the upper chamber through the first channel structure, the second hole 4 is connected to the middle chamber through the second channel structure, and the third hole 5 is connected to the lower chamber through the third channel structure.

[0023] The third hole 5 serves as the sample inlet for introducing the test liquid. The test liquid passes sequentially through the first filter structure 30 and the second filter structure 40 in the chamber 6, and is discharged through the first hole 3, which serves as the waste outlet. The test liquid is filtered by the first filter structure 30 to remove larger particles. The first filter structure 30 is, for example, a 10μm filter screen, where particles larger than 10μm are captured and collected. Then, it is filtered by the second filter structure 40 to remove smaller particles. The second filter structure 40 is, for example, a 1μm filter screen, where particles between 1μm and 10μm are captured and collected.

[0024] In addition, the liquid to be tested can be pre-filtered with a 500μm filter, so that after the liquid to be tested passes through the first filter structure 30, particles with a size of 10μm-500μm are captured on the first filter structure 30, making the particle size more controllable and effectively preventing the filter from being easily clogged.

[0025] The second hole 4 serves as the backflushing fluid inlet, allowing backflushing fluid to flow sequentially through the second filter structure 40 and the first filter structure 30. This backflushing fluid flushes out particles captured on the first filter structure 30 and the second filter structure 40 through the third hole 5 (the first hole 3 can be pre-blocked). As the backflushing fluid passes through the filter structures, it displaces the particles, creating a discrete flow that then follows the channel direction into the detection device 7. The backflushing fluid can be, for example, anhydrous ethanol. Using anhydrous ethanol as the backflushing fluid reduces the evaporation time of the residual backflushing fluid on the sample, thereby reducing detection waiting time and improving detection efficiency.

[0026] The detection device 7 has multiple detection grooves 71 on its surface. After being flushed out by the backflushing liquid, the particles flow into the detection grooves 71 for further Raman spectroscopy detection, such as effectively detecting marine microplastic particles. The detection device 7 can be made of high-purity aluminum plate. The high-purity aluminum material of the entire detection device 7 can reduce interference from the Raman spectroscopy detection background and enhance the Raman spectral signal of the particles, thereby achieving the effect of effectively detecting marine microplastic particles.

[0027] The detection groove 71 of the detection device 7 has a diameter of 5 mm, a depth of 5 mm, and a capacity of 98 μL. Each sample can ultimately be directed to one detection groove 71.

[0028] After the particles are captured by the first filter structure 30 and the second filter structure 40, and before the backflushing liquid is introduced to flush out the particles, a digestion solution, such as a 30% H2O2 solution, can be introduced into the third hole 5. After the digestion solution completely covers the first filter structure 30 and the second filter structure 40, the first hole 3 and the second hole 4 are blocked, so that the microfluidic device 1 is filled with the digestion solution to digest the biomass and the like to eliminate the signal interference of Raman spectroscopy detection.

[0029] Microfluidic device 1 is based on microfluidic technology. Specifically, the support structure 2 of microfluidic device 1 is a layered structure, as shown in the figure. Figure 2 The support structure 2, from top to bottom, includes a top layer 21, a first strip layer 22, a first support layer 23, a first flat layer 24, a second strip layer 25, a second support layer 26, a second flat layer 27, a third flat layer 28, a third strip layer 29, and a bottom layer 20. All layers are tightly bonded to form the overall support structure 2. Each layer can be made of PMMA board material, which has good light transmittance and is easy to observe.

[0030] Sub-chambers 61 are formed in the first strip layer 22, the first support layer 23, the first flat sheet layer 24, the second strip layer 25, the second support layer 26, the second flat sheet layer 27, the third flat sheet layer 28, and the third strip layer 29. The sub-chambers 61 of each layer are combined to form a complete chamber 6. The second filter structure 40 is disposed between the first support layer 23 and the first flat sheet layer 24, and the first filter structure 30 is disposed between the second flat sheet layer 27 and the third flat sheet layer 28.

[0031] The first hole 3 penetrates downward from the top layer 21 to the first strip layer 22, thereby forming a first sub-hole 31 in each layer 22 it passes through. The first strip layer 22 is provided with a first channel structure 221, which connects the first sub-hole 31 of the first strip layer 22 with the sub-chamber 61.

[0032] The second hole 4 penetrates downwards from the top layer 21 to the second strip layer 25, thereby forming a second sub-hole 41 in each layer it passes through. A second channel structure 251 is provided in the second strip layer 25, which connects the second sub-hole 41 of the second strip layer 25 with the sub-chamber 61.

[0033] The third hole 5 penetrates downwards from the top layer 21 to the third strip layer 29, thereby forming a third sub-hole 51 in each layer it passes through. A third channel structure 291 is provided in the third strip layer 29, which connects the third sub-hole 51 of the third strip layer 29 with the sub-chamber 61.

[0034] The first support structure 231 is provided in the sub-chamber 61 of the first support layer 23. The first support structure 231 can be used to support the second filter structure 40, preventing the second filter structure 40 from deforming under fluid impact pressure, thereby improving the pressure resistance of the entire device. The first support structure 231 can be in the form of a central ring with radial distribution around it to provide uniform support for the second filter structure 40; of course, the first support structure 231 can also be other support shapes.

[0035] The second support layer 26 has a second support structure 261 in its sub-chamber 61. The second support structure 261 can support the first filter structure 30 and prevent the first filter structure 30 from deforming under fluid impact pressure, thereby improving the pressure resistance of the entire device. The second support structure 261 can have the same or different shape as the first support structure 231.

[0036] Example 2 Reference Figure 1-13 This embodiment provides a pretreatment method for microplastic particles, including the following steps: S1: Provide a microfluidic device 1 as described in Example 1; S2: Block the second hole 4 (backflush inlet) of the microfluidic device 1 using a blocking device, and introduce the test solution into the third hole 5 (sample inlet), so that all the test particles are collected on the first filter structure 30 and the second filter structure 40 of the microfluidic device 1. S3: Pass 30% H2O2 digestion solution into the third hole 5. After the digestion solution completely covers the first filter structure 30 and the second filter structure 40, block the first hole 3 and the second hole 4 so that the microfluidic device 1 is filled with digestion solution. S4: Remove the plugging device from the first hole 3 and introduce sterile water into the third hole 5 to wash away excess digestion solution and plastic particle digestion products. S5: Remove the blocking device from the second hole 4 and move it to the first hole 3 (waste liquid outlet) to block it. At the same time, invert the microfluidic device 1 and introduce backflushing liquid into the second hole 4. Place the detection device 7 under the third hole 5. The backflushing liquid flows through the first filter structure 30 and the second filter structure 40 in sequence, and flows out through the third hole 5 into the detection groove 71 of the detection device 7.

[0037] This invention develops a microfluidic device capable of pre-treating a wide range of plastic particles (1-500 μm) in the environment, enabling the filtration, enrichment, digestion, and recovery of microplastic particles, thereby improving the processing efficiency of microplastics in environmental samples. The microfluidic device of this invention is suitable for processing samples from various environments, such as marine, river, lake, and drinking water environments, demonstrating its broad applicability. Furthermore, since the size of bacteria in the environment (1-5 μm) is typically within the processing range of this device, it is also suitable for pre-treating bacteria in environmental samples. Moreover, this invention integrates a detection device suitable for Raman spectroscopy, allowing the processed sample to be directly used for Raman spectroscopy detection, greatly simplifying the manual pre-treatment process and reducing the use of digestion solution. The microfluidic device provided by this invention can effectively enrich and pre-treat microplastics in environmental samples and seamlessly integrates with Raman spectroscopy technology, thus providing an efficient, accurate, and convenient pre-treatment tool for outdoor monitoring of microplastics.

[0038] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A microfluidic device for pretreatment of microplastic particles, characterized in that, The device includes a support structure, within which a closed chamber is provided. A first filter structure and a second filter structure are also supported side-by-side within the support structure. The pore size of the first filter structure is larger than that of the second filter structure. The first and second filter structures divide the chamber along its height into an upper chamber, a middle chamber, and a lower chamber. The support structure also has a first hole, a second hole, and a third hole, all extending from the outer surface of the support structure into its interior. The first hole connects to the upper chamber via a first channel structure, the second hole connects to the middle chamber via a second channel structure, and the third hole connects to the lower chamber via a third channel structure.

2. The microfluidic device according to claim 1, characterized in that: The third hole is used to introduce the liquid to be tested or the digestion solution; the second hole serves as the backflushing liquid inlet for introducing backflushing liquid.

3. The microfluidic device according to claim 1, characterized in that: The first filter structure is a 10μm filter screen, and the second filter structure is a 1μm filter screen.

4. The microfluidic device according to claim 1, characterized in that: The support structure is a layered structure, comprising, from top to bottom, a top layer, a first strip layer, a first support layer, a first flat sheet layer, a second strip layer, a second support layer, a second flat sheet layer, a third flat sheet layer, a third strip layer, and a bottom layer, with each layer tightly bonded to form the overall support structure. Sub-chambers are formed in each of the first strip layer, the first support layer, the first flat sheet layer, the second strip layer, the second support layer, the second flat sheet layer, the third flat sheet layer, and the third strip layer, and these sub-chambers combine to form the complete chamber. A second filter structure is disposed between the first support layer and the first flat sheet layer, and the first filter structure is disposed between the second flat sheet layer and the third flat sheet layer.

5. The microfluidic device according to claim 4, characterized in that: The first hole penetrates downwards from the top layer to the first strip layer, thereby forming a first sub-hole in each layer it passes through; the first strip layer is provided with a first channel structure, which connects the first sub-hole of the first strip layer with the sub-cavity.

6. The microfluidic device according to claim 4, characterized in that: The second hole penetrates downwards from the top layer to the second strip layer, thereby forming a second sub-hole in each layer it passes through; the second strip layer is provided with a second channel structure, which connects the second sub-hole of the second strip layer with the sub-cavity.

7. The microfluidic device according to claim 4, characterized in that: The third hole penetrates downwards from the top layer to the third strip layer, thereby forming a third sub-hole in each layer it passes through; the third strip layer is provided with a third channel structure, which connects the third sub-hole of the third strip layer with the sub-cavity.

8. The microfluidic device according to claim 4, characterized in that: The first support layer has a first support structure in its sub-cavity, which is used to support the second filter structure; the second support layer has a second support structure in its sub-cavity, which can be used to support the first filter structure.

9. A microfluidic system for pretreatment of microplastic particles, characterized in that, The device includes the microfluidic device as described in any one of claims 1-8, and further includes a detection device, which is made of high-purity aluminum plate and has a plurality of detection grooves on its surface.

10. A method for pretreatment of microplastic particles, characterized in that, Includes the following steps: S1: Provide a microfluidic device as described in any one of claims 1-8; S2: Block the second hole of the microfluidic device using a blocking device, and introduce the test solution into the third hole, so that all the test particles are collected on the first filter structure and the second filter structure of the microfluidic device; S3: Pass the digestion solution into the third hole. After the digestion solution completely covers the first filter structure and the second filter structure, block the first hole and the second hole so that the microfluidic device is filled with digestion solution. S4: Remove the blocking device from the first hole and introduce sterile water into the third hole to wash away excess digestion solution and plastic particle digestion products; S5: Remove the blocking device from the second hole and move it to the first hole to block it. At the same time, invert the microfluidic device and introduce backflushing fluid into the second hole. Place the detection device under the third hole. The backflushing fluid flows through the second filter structure and the first filter structure in sequence, and flows out through the third hole into the detection groove of the detection device.

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