A device and method for screening and separating microplastic particles based on light-induced dielectrophoresis

Abstract

This invention provides a microplastic particle screening and separation device and method based on photoinduced dielectrophoresis. The device comprises a photoinduced dielectrophoresis chip consisting of a first illumination region, a second illumination region, a controllable barrier block, and a microchannel layer. By applying light to different positions on the photoinduced dielectrophoresis chip, the conductivity at the illumination position changes, thereby generating a non-uniform electric field. Due to the different radii of the microplastic particles, the magnitude of the photoinduced dielectrophoretic force varies. Larger-radius microplastic particles experience a greater dielectrophoretic force and cannot pass through the illumination region, while smaller-radius microplastic particles experience a smaller dielectrophoretic force and can flow to the sample outlet. By changing the position of the controllable barrier block, the separation of microplastic particles of three different radii can be achieved. The microplastic particle screening and separation device and method based on photoinduced dielectrophoresis described in this invention can achieve the separation and screening of target microplastics of different sizes using contactless photoinduced dielectrophoresis force.

Description

Technical Field

[0001] This invention relates to the field of marine microplastic particle analysis technology, and more particularly to a microplastic particle screening and separation device and method based on photoinduced dielectrophoresis. Background Technology

[0002] Microplastics are generally defined as plastic fragments and particles with a diameter of less than 5 mm. They enter natural ecosystems from various sources, including cosmetics, clothing, and industrial processes. Common types of plastics include polyethylene (PE), polypropylene (PP), polystyrene (PS), polyvinyl chloride (PVC), and polyamide (PA). Microplastics are characterized by their large specific surface area, rapid migration speed, and high hydrophobicity, thus they can accumulate abundant pollutants and serve as long-term carriers in aquatic ecosystems.

[0003] The ocean is the final destination of microplastic waste worldwide. Large quantities of microplastics are transported by ocean currents, causing transboundary pollution that impacts marine ecosystems and human health and safety, raising significant global concerns. 70%–80% of the plastics reaching the ocean are transported by rivers, primarily from improperly disposed waste during manufacturing and use, agriculture, land use, and sewage. Because plastic polymers exhibit minimal biodegradability, they can remain in the environment for hundreds to thousands of years, during which time they break down into smaller fragments due to ultraviolet radiation, physical forces, and hydrolysis. Microplastics in aquatic and soil environments cross-contaminate each other through wastewater reuse and groundwater infiltration, then migrate from lower trophic levels to higher trophic levels, ultimately returning to the human body and causing harm. Studies show that smaller microplastics are more likely to accumulate in organisms, and it is generally believed that the smaller the particle size of microplastics, the greater the harm to the ecosystem.

[0004] Currently, the main analytical methods for marine microplastics include visual analysis, Fourier transform infrared spectroscopy, Raman spectroscopy, and thermal analysis. Mass spectrometry Other methods include scanning electron microscopy-energy dispersive spectroscopy (SEM-EDS). However, these methods require large sample volumes, involve expensive equipment, are complex in operation, and have low separation efficiency. Therefore, it is crucial to invent a marine microplastic particle screening and separation device to rapidly and efficiently complete research related to marine microplastic particles.

[0005] Photoinduced dielectrophoresis utilizes photosensitive materials in chip fabrication. Light patterns are projected onto these materials to form virtual electrodes, and the resulting non-uniform electric field can be used to manipulate cells and microparticles. Compared to dielectrophoresis, photoinduced dielectrophoresis does not require the fabrication of complex electrodes; it only requires changing the pattern of the projected light, making the manipulation process more convenient. It has broad application value in cell screening, transport, and capture in fields such as biology and medicine. Summary of the Invention

[0006] To address the aforementioned technical problems, this invention provides a microplastic particle screening and separation device and method based on photoinduced dielectrophoresis. The invention generates a non-uniform electric field by applying light to different locations on a photoinduced dielectrophoresis chip, causing variations in conductivity at the illuminated locations. Due to the different radii of the microplastic particles, the magnitude of the photoinduced dielectrophoretic force varies. Larger-radius microplastic particles experience a greater dielectrophoretic force and cannot pass through the illuminated area, while smaller-radius microplastic particles experience a smaller dielectrophoretic force and can flow to the sample outlet. By changing the position of a controllable barrier block, the separation of microplastic particles with three different radii can be achieved.

[0007] The technical means employed in this invention are as follows:

[0008] A microplastic particle screening and separation device based on photoinduced dielectrophoresis includes: a photoinduced dielectrophoresis chip composed of a first illumination region, a second illumination region, a controllable barrier block, and a microchannel layer; wherein:

[0009] The microchannel layer includes a microfluidic channel, a sample inlet, a first outlet, and a second outlet; the microfluidic channel includes a straight channel, a first branched channel, and a second branched channel; the sample inlet is connected to one end of the straight channel, one end of the first branched channel and one end of the second branched channel are both connected to the other end of the straight channel, and the first outlet and the second outlet are respectively connected to the other ends of the first branched channel and the second branched channel;

[0010] The first and second illumination areas are set on the straight channel to apply light at different positions, causing the conductivity at the illumination position to change, thereby generating a non-uniform electric field.

[0011] The controllable barrier block is movably connected at the junction of the straight channel and the first branch channel, or movably connected at the junction of the straight channel and the second branch channel. By changing the position of the controllable barrier block, the separation of three microplastic particles with different radii can be achieved.

[0012] In use, the microplastic particle sample is injected through the sample inlet, passes through the first and second illumination areas, and the smaller microplastic particles flow out from the second outlet. By changing the position of the controllable barrier block through illumination control, the illumination of the second illumination area is turned off, and the slightly larger microplastic particles flow out from the first outlet. After the sample at the first outlet is collected, the illumination of the first illumination area is turned off, and the largest microplastic particles flow out from the first outlet.

[0013] Furthermore, the photoinduced dielectrophoresis chip also includes ITO layers connected to the top and bottom of the microchannel layer, respectively. The top and bottom of the ITO layers are respectively connected to glass layers, and a signal generator is connected between the ITO layers through wires to generate an alternating electric field in the microfluidic channel.

[0014] Furthermore, a photoconductive layer is sprayed onto the inner surface of the ITO layer at the bottom of the microchannel layer using plasma-enhanced chemical vapor deposition. The photoconductive layer is hydrogenated amorphous silicon.

[0015] Furthermore, the microchannel layer is made of PDMS material and is fabricated using a photolithography casting process.

[0016] Furthermore, by projecting light patterns onto the controllable obstacle block and manipulating the movement of the light patterns, the position of the controllable obstacle block can be changed, thereby achieving selective closure of the channel.

[0017] Furthermore, the first and second illumination areas use projector light sources to focus light through lenses and reflect it onto the photoinduced dielectrophoresis chip, thereby generating optical virtual electrodes on the photoinduced dielectrophoresis chip. Applying light to different positions on the photoinduced dielectrophoresis chip changes the conductivity of the illumination area, thereby generating a high-gradient non-uniform electric field.

[0018] Furthermore, the first and second sample outlets are the same size and width and are located on the same plane.

[0019] Furthermore, an angle is provided between the first branch channel and the second branch channel.

[0020] The present invention also provides a method for screening and separating microplastic particles based on photoinduced dielectrophoresis, implemented using the above-mentioned microplastic particle screening and separation device, comprising:

[0021] S1. Plasma cleaning:

[0022] The bonded microplastic particle screening and separation device based on photoinduced dielectrophoresis was placed in a plasma cleaner for plasma cleaning.

[0023] S2. Inject the solution of microplastic particles to be tested:

[0024] Inject the microplastic particle solution into the sample inlet using a syringe pump;

[0025] S3, Generates an alternating electric field:

[0026] Connect the other ends of the wires connecting the top and bottom of the ITO layer to the signal generator to generate an alternating electric field in the microfluidic channel.

[0027] S4. Screening and separation of microplastic particles:

[0028] The projector projects the designed electrode pattern onto the photoinduced dielectrophoresis chip, and the separation effect of microplastic particles is observed with a microscope. The voltage and frequency of the signal generator are adjusted to improve the separation efficiency.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. The microplastic particle screening and separation device and method based on photoinduced dielectrophoresis provided by the present invention is simple to operate, lightweight and portable, and can achieve rapid and accurate sorting without the need to label microplastic particles. It does not require much from the experimenters, who only need to master the correct experimental methods.

[0031] 2. The microplastic particle screening and separation device and method based on photoinduced dielectrophoresis provided by the present invention can realize the separation and screening of target microplastics of different sizes by utilizing non-contact photoinduced dielectrophoresis force.

[0032] 3. The microplastic particle screening and separation device and method based on photoinduced dielectrophoresis provided by the present invention requires no sample pretreatment, is low in cost, flexible in design, has a short reaction time, and can be integrated with other functions.

[0033] 4. The microplastic particle screening and separation device and method based on photoinduced dielectrophoresis provided by the present invention uses optical electrodes instead of the previous physical electrodes, realizing large-scale cell manipulation. From chip processing to packaging, the process is simple and low-cost, avoiding complex processing, making the experiment flexible and reusable.

[0034] 5. The microplastic particle screening and separation device and method based on photoinduced dielectrophoresis provided by the present invention can change the shape of the virtual electrode at any time by changing the light pattern, and can be used to perform more complex experiments, which is in line with the manipulation advantages of photoinduced dielectrophoresis.

[0035] Based on the above reasons, this invention can be widely applied in fields such as marine microplastic particle analysis. Attached Figure Description

[0036] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0037] Figure 1 This is a schematic diagram of the chip channel of the device of the present invention.

[0038] Figure 2 This is a schematic diagram of the principle of the device of the present invention.

[0039] Figure 3 This is a schematic diagram of the chip structure of the device of the present invention.

[0040] Figure 4This is a schematic diagram showing the controllable obstacle block moving completely and the second illumination area being turned off in the device of the present invention.

[0041] In the figure: 1. Sample inlet; 2. First illumination area; 3. Second illumination area; 4. Microfluidic channel; 5. Controllable barrier block; 6. First outlet; 7. Second outlet; 8. Angle; 9. Glass layer; 10. Light guide layer; 11. Microchannel layer; 12. ITO layer; 13. Wire; 14. Liquid medium; 15. Microplastic particles; 16. Illumination area. Detailed Implementation

[0042] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other. The present invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0043] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, 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. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. 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.

[0044] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0045] Unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps described in these embodiments do not limit the scope of the invention. It should also be understood that, for ease of description, the dimensions of the various parts shown in the drawings are not drawn to actual scale. Techniques, methods, and devices known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and devices should be considered part of the specification. In all examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values. It should be noted that similar reference numerals and letters in the following figures denote similar items; therefore, once an item is defined in one figure, it need not be further discussed in subsequent figures.

[0046] In the description of this invention, it should be understood that the orientation or positional relationship indicated by directional terms such as "front, back, up, down, left, right", "horizontal, vertical, horizontal" and "top, bottom" is generally based on the orientation or positional relationship shown in the accompanying drawings, and is only for the convenience of describing this invention and simplifying the description. Unless otherwise stated, these directional terms do not indicate or imply that the device or element referred to must have a specific orientation or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on the scope of protection of this invention. The directional terms "inner" and "outer" refer to the inner and outer contours relative to the outline of each component itself.

[0047] For ease of description, spatial relative terms such as "above," "over," "on the upper surface of," "above," etc., are used herein to describe the spatial positional relationship of a device or feature as shown in the figures to other devices or features. It should be understood that spatial relative terms are intended to encompass different orientations in use or operation besides the orientation of the device as described in the figures. For example, if the device in the figures is inverted, a device described as "above" or "above" other devices or structures would subsequently be positioned as "below" or "under" other devices or structures. Thus, the exemplary term "above" can include both "above" and "below." The device may also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatial relative descriptions used herein will be interpreted accordingly.

[0048] Furthermore, it should be noted that the use of terms such as "first" and "second" to define components is merely for the purpose of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore should not be construed as limiting the scope of protection of this invention.

[0049] like Figure 1As shown, this invention provides a microplastic particle screening and separation device based on photoinduced dielectrophoresis, comprising: a photoinduced dielectrophoresis chip composed of a first illumination region 2, a second illumination region 3, a controllable barrier block 5, and a microchannel layer 11; wherein:

[0050] The microchannel layer 11 includes a microfluidic channel 4, a sample inlet 1, a first outlet 6, and a second outlet 7. The microfluidic channel 4 includes a straight channel, a first branched channel, and a second branched channel. The sample inlet 1 is connected to one end of the straight channel, and one end of each of the first and second branched channels is connected to the other end of the straight channel. The first outlet 6 and the second outlet 7 are respectively connected to the other ends of the first and second branched channels.

[0051] The first illumination area 2 and the second illumination area 3 are set on the straight channel to apply light at different positions, so that the conductivity at the illumination position changes, thereby generating a non-uniform electric field.

[0052] The controllable barrier block 5 is movably connected at the connection between the straight channel and the first branch channel, or movably connected at the connection between the straight channel and the second branch channel. By changing the position of the controllable barrier block 5, the separation of three microplastic particles with different radii can be achieved.

[0053] When in use, the microplastic particle sample is injected from the sample inlet (1), passes through the first illumination area 2 and the second illumination area 3, and the microplastic particles with smaller radii flow out from the second outlet 7. By changing the position of the controllable barrier block 5 through illumination control, the illumination of the second illumination area 3 is turned off, and the microplastic particles with slightly larger radii flow out from the first outlet 6. After the sample at the first outlet 6 is collected, the illumination of the first illumination area 2 is turned off, and the microplastic particles with the largest radii flow out from the first outlet 6.

[0054] In specific implementation, as a preferred embodiment of the present invention, such as Figure 2 , 3 As shown, the photoinduced dielectrophoresis chip also includes ITO layers 12 connected to the top and bottom of the microchannel layer 11, respectively. The top and bottom of the ITO layers 12 are connected to glass layers 9, and a signal generator is connected between the ITO layers 12 via wires 13 to generate an alternating electric field in the microfluidic channel 4. In this embodiment, the thickness of the ITO layers 12 is 120 nm.

[0055] In specific implementation, as a preferred embodiment of the present invention, such as Figure 2 , 3 As shown, a photoconductive layer 10 is sprayed onto the inner surface of the ITO layer 12 at the bottom of the microchannel layer 11 using plasma-enhanced chemical vapor deposition. The photoconductive layer 10 is hydrogenated amorphous silicon with a thickness of 500 nm.

[0056] In a preferred embodiment of the present invention, the microchannel layer 11 is made of PDMS material and fabricated using a photolithography casting process. The fabrication process includes the following steps:

[0057] Vacuuming: Pour liquid PDMS and curing agent into a clean glass in a 10:1 ratio, stir evenly with a stirring rod, and then place it in a vacuum chamber to remove the air from the glass to prevent air bubbles from forming after the PDMS has cured.

[0058] Casting and curing: After vacuuming, pour PDMS onto the substrate of the device's discrete chip, then place it in an oven to stand and wait for the PDMS to cure.

[0059] Cleaning: Trim the cured PDMS chip according to the graphic size, drill holes in the chip's inlet and outlet with a hole punch, and then place the chip and glass slide in a plasma cleaner for cleaning.

[0060] Bonding: The glass slide and PDMS chip are removed from the plasma cleaner and quickly bonded together.

[0061] In this embodiment, the width of the microfluidic channel 4 is 120 μm, the width of the sample inlet 1 is 120 μm, the width of the first sample outlet 6 is 90 μm, and the width of the second sample outlet 7 is 90 μm. The first sample outlet 6 and the second sample outlet 7 are the same size, of equal width, and located on the same plane. An included angle 8 of 60° is provided between the first branch channel and the second branch channel.

[0062] In a preferred embodiment of the present invention, the first illumination area 2 and the second illumination area 3 employ a projector light source. Light is focused through a lens and reflected by a prism onto the photoinduced dielectrophoresis chip, thereby generating optical virtual electrodes on the chip. Applying illumination to different positions on the chip alters the conductivity of the illumination area, thus generating a high-gradient non-uniform electric field. It should be noted that in actual operation, the projection of light onto the photoinduced dielectrophoresis chip can be controlled according to various operational factors to form corresponding illumination areas, and the illumination areas projected onto the chip are not limited to the specific embodiment (…). Figure 1 The area shown is limited to the region indicated. In this embodiment, the length of the first illumination region 2 is 200 μm, the length of the second illumination region 3 is 200 μm, and the distance between the first illumination region 2 and the second illumination region 3 is 150 μm. The voltage of the first illumination region 2 is 3.6V, the voltage of the second illumination region 3 is 5V, and the frequency is 10KHz, but this is not a limitation.

[0063] In a preferred embodiment of the invention, a light pattern is projected onto the controllable obstacle block 5 and its movement is manipulated to change the position of the controllable obstacle block 5, thereby achieving selective closure of the channel. In this embodiment, the movable obstacle block 5 is made of SU-8 material.

[0064] The present invention also provides a method for screening and separating microplastic particles based on photoinduced dielectrophoresis, implemented using the above-mentioned microplastic particle screening and separation device, comprising:

[0065] S1. Plasma cleaning:

[0066] The bonded microplastic particle screening and separation device based on photoinduced dielectrophoresis was placed in a plasma cleaner for plasma cleaning.

[0067] S2. Inject the solution of microplastic particles to be tested:

[0068] Inject the microplastic particle solution into the sample inlet using a syringe pump;

[0069] S3, Generates an alternating electric field:

[0070] Connect the other ends of the wires connecting the top and bottom of the ITO layer to the signal generator to generate an alternating electric field in the microfluidic channel.

[0071] S4. Screening and separation of microplastic particles:

[0072] The projector projects the designed electrode pattern onto the photoinduced dielectrophoresis chip, and the separation effect of microplastic particles is observed with a microscope. The voltage and frequency of the signal generator are adjusted to improve the separation efficiency.

[0073] In summary, this invention achieves efficient separation of microplastic particles in a straight channel without pre-installed fixed physical metal electrodes. More importantly, after completing the reagent separation function, other subsequent tasks can be performed by flexibly switching the pattern of the optical pseudo-electrode, making it possible to integrate multiple functions on the same chip simultaneously, thus offering operational flexibility.

[0074] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A device for the screening separation of microplastic particles based on light-induced dielectrophoresis, characterized by include: A photoinduced dielectrophoresis chip consisting of a first illumination region (2), a second illumination region (3), a controllable barrier block (5), and a microchannel layer (11); wherein: The microchannel layer (11) includes a microfluidic channel (4), a sample inlet (1), a first outlet (6), and a second outlet (7); the microfluidic channel (4) includes a straight channel, a first branch channel, and a second branch channel; the sample inlet (1) is connected to one end of the straight channel, and one end of the first branch channel and the second branch channel are both connected to the other end of the straight channel; the first outlet (6) and the second outlet (7) are respectively connected to the other ends of the first branch channel and the second branch channel. The first illumination area (2) and the second illumination area (3) are set on the straight channel to apply light at different positions, so that the conductivity at the illumination position changes, thereby generating a non-uniform electric field. The controllable barrier block (5) is movably connected at the connection between the straight channel and the first branch channel, or movably connected at the connection between the straight channel and the second branch channel. By changing the position of the controllable barrier block (5), the separation of three microplastic particles with different radii can be achieved. When in use, the microplastic particle sample is injected from the sample inlet (1), passes through the first illumination area (2) and the second illumination area (3), and the microplastic particles with smaller radii flow out from the second outlet (7). By changing the position of the controllable barrier block (5) through illumination control, the illumination of the second illumination area (3) is turned off, and the microplastic particles with slightly larger radii flow out from the first outlet (6). After the sample from the first outlet (6) is collected, the illumination of the first illumination area (2) is turned off, and the microplastic particles with the largest radii flow out from the first outlet (6).

2. The microplastic particle screening and separation device based on photoinduced dielectrophoresis according to claim 1, characterized in that, The photoinduced dielectrophoresis chip also includes ITO layers (12) connected to the top and bottom of the microchannel layer (11), glass layers (9) connected to the top and bottom of the ITO layers (12), and a signal generator connected between the ITO layers (12) by wires (13) to generate an alternating electric field in the microfluidic channel (4).

3. The microplastic particle screening and separation device based on photoinduced dielectrophoresis according to claim 2, characterized in that, A photoconductive layer (10) is sprayed onto the inner surface of the ITO layer (12) at the bottom of the microchannel layer (11) using plasma-enhanced chemical vapor deposition. The photoconductive layer (10) is hydrogenated amorphous silicon.

4. The microplastic particle screening and separation device based on photoinduced dielectrophoresis according to claim 3, characterized in that, The microchannel layer (11) is made of PDMS material and is fabricated using a photolithography casting process.

5. The microplastic particle screening and separation device based on photoinduced dielectrophoresis according to claim 1, characterized in that, By projecting a light pattern onto the controllable obstacle block (5) and manipulating the movement of the light pattern, the position of the controllable obstacle block (5) can be changed, thereby achieving selective closure of the channel.

6. The microplastic particle screening and separation device based on photoinduced dielectrophoresis according to claim 1, characterized in that, The first illumination area (2) and the second illumination area (3) use a projector light source to focus the light through a lens and reflect it onto the photoinduced dielectrophoresis chip, thereby generating an optical virtual electrode on the photoinduced dielectrophoresis chip. Applying light to different positions on the photoinduced dielectrophoresis chip changes the conductivity of the illumination area, thereby generating a high gradient non-uniform electric field.

7. The microplastic particle screening and separation device based on photoinduced dielectrophoresis according to claim 1, characterized in that, The first sample outlet (6) and the second sample outlet (7) are the same size and have the same width and are located on the same plane.

8. The microplastic particle screening and separation device based on photoinduced dielectrophoresis according to claim 1, characterized in that, An angle (8) is provided between the first branch channel and the second branch channel.

9. A method for screening and separating microplastic particles based on photoinduced dielectrophoresis, implemented using the microplastic particle screening and separation device according to any one of claims 1-8, characterized in that, include: S1. Plasma cleaning: The bonded microplastic particle screening and separation device based on photoinduced dielectrophoresis was placed in a plasma cleaner for plasma cleaning. S2. Inject the solution of microplastic particles to be tested: Inject the microplastic particle solution into the sample inlet using a syringe pump; S3, Generates an alternating electric field: Connect the other ends of the wires connecting the top and bottom of the ITO layer to the signal generator to generate an alternating electric field in the microfluidic channel. S4. Screening and separation of microplastic particles: The projector projects the designed electrode pattern onto the photoinduced dielectrophoresis chip, and the separation effect of microplastic particles is observed with a microscope. The voltage and frequency of the signal generator are adjusted to improve the separation efficiency.

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