Microfluidic chip and micro-nano particle separation device

Abstract

The application discloses a microfluidic chip and a micro-nano particle separation device, and relates to the technical field of microfluidic chips. The microfluidic chip comprises a channel layer; the channel layer is a spiral channel; the spiral channel comprises an inner side wall and an outer side wall; the inner side wall is a flat wall, and the outer side wall is a wave-shaped wall. In the application, through the innovative asymmetric wave-shaped wall spiral channel design, a unique separation effect of small particles being close to the inner side and large particles being close to the outer side is realized, and the separation mode of a traditional spiral chip is broken. The microfluidic chip structure can realize continuous separation of high-throughput and high-efficiency micro plastics without an external field, and is simple to operate and low in cost. The separated particles can be directly connected to various analysis instruments, and an efficient and reliable pretreatment solution is provided for size, component and content analysis of micro plastics and micro-nano particles.

Description

Technical Field

[0001] This utility model belongs to the field of chips and relates to a microfluidic chip and a micro / nano particle separation device. Background Technology

[0002] Since the 1950s, plastics production has been on a large scale and has continued to expand. By 2021, global annual plastic production had exceeded 380 million tons, with an average annual growth rate of approximately 4%. While plastics have brought numerous conveniences to human society and profoundly changed modern lifestyles, due to inadequate management and low recycling efficiency, a large amount of plastic waste ultimately ends up in the natural environment. In 2004, a published article first introduced the term "microplastics" to describe plastic residue fragments with a diameter of approximately 20 μm. Today, microplastics are generally defined as particles smaller than 5 mm in size and are recognized as a highly diverse pollutant with global impact. Their sources are diverse, including single-use microplastics added to products such as cosmetics and coatings, particles and fragments from plastic production raw materials, secondary microplastics generated during use due to wear and tear (such as from textiles and tires), and fragments formed from the breakage of large plastic products in the environment. Microplastics can migrate widely with the help of wind and water currents and have been detected in various environments, from ocean surfaces to deep-sea sediments, farmland to mountain peaks, sea ice, lakes, and rivers. Microplastics have been found in more than 1,300 aquatic and terrestrial species, from invertebrates at the bottom of the food chain to apex predators, leaving scientific evidence of their impact at every level of biological tissue, from cells to ecosystems.

[0003] The impact of microplastics on biological health often follows a dose-response relationship, but mounting evidence suggests that particle size is a key factor influencing their environmental toxicology. Particle size directly determines the migration capacity of microplastics in the aquatic environment, their likelihood of ingestion by organisms, their residence time within organisms, their potential to cross tissue barriers and metastasize to organs, and their efficiency of transfer along the food chain. Studies have shown that the toxic effects of microplastics tend to increase as particle size decreases. This is mainly attributed to their small size and high specific surface area: smaller particles are more likely to bind with other pollutants in the environment, forming complex carriers; they are also more likely to penetrate biological barriers such as cell membranes, thus accumulating in various aquatic organisms and producing complex synergistic toxicities. Therefore, in assessing the environmental risks of microplastics, in addition to focusing on their total amount, particle size distribution has become a crucial parameter that cannot be ignored.

[0004] Efficient methods for separating and detecting microplastics of different sizes are crucial for studying their environmental behavior and biotoxicity. However, commonly used separation techniques, such as sieving, while simple to operate, have significant drawbacks in practical applications, particularly in terms of efficiency and accuracy. This method relies on physical sieves, has limited resolution, and is mainly suitable for larger particles (typically greater than 25 micrometers). For even smaller microplastics, they are easily trapped on the sieve or container surface due to electrostatic adsorption or physical adhesion, leading to significant sample loss. Furthermore, frequent manual operations can easily introduce external contaminants (such as airborne fibers or other particles), thus interfering with the accuracy and reliability of the analytical results. Flotation separation based on density differences is currently the mainstream method for processing microplastic samples, such as using saturated NaCl solutions. However, this method is essentially a coarse separation based on density, unable to achieve precise particle size separation of microplastics. Its separation efficiency heavily depends on the density difference between the target particle and the separating solution. For microplastics with densities close to those of the separating solution, or for heterogeneous particles formed by surface aging or biofilm adhesion, the separation efficiency of this method is significantly reduced. Therefore, density flotation is ill-suited to the needs of refined environmental behavior and toxicological studies of microplastic particle size. Although advanced technologies such as fluid dynamic chromatography and centrifugal field fractionation can theoretically achieve high-resolution particle size separation, these methods are expensive, complex to operate, and have extremely low sample throughput, making it difficult to handle the large volume and complexity of environmental samples. Existing separation technologies have shortcomings in efficiency, accuracy, and high-throughput capabilities, which not only lead to a serious underestimation of small-sized microplastics but also hinder a deeper understanding of the environmental fate, bioavailability, and toxicity mechanisms of microplastics of different particle sizes. Therefore, developing efficient, accurate, and standardized particle size separation technologies is a key direction that urgently needs breakthroughs in the field of microplastic research. Utility Model Content

[0005] This application provides a microfluidic chip and a micro / nano particle separation device to solve or alleviate one or more of the technical problems mentioned above.

[0006] The first aspect of this application provides a microfluidic chip, the microfluidic chip including a channel layer; The channel layer is a spiral channel, and the spiral channel includes an inner wall and an outer wall; The inner wall is a flat wall, and the outer wall is a wavy wall.

[0007] Preferably, the ratio of the amplitude of the corrugated wall to the width of the spiral channel is (0.1-0.5):1.

[0008] Preferably, the ratio of the wavelength of the corrugated wall to the width of the spiral channel is (1-5):1.

[0009] Preferably, in the spiral channel, the distance from the flat wall to the corresponding wave crest position of the wavy wall is 120-660 μm.

[0010] Preferably, the distance from the flat wall to the corresponding trough of the wavy wall is 80-500 μm.

[0011] Preferably, the distance between adjacent channels, from the outer flat wall of the spiral channel to the crest of the inner wavy wall of the spiral channel, is 300-800 μm.

[0012] Preferably, the distance between adjacent channels, from the outer flat wall of the spiral channel to the trough of the inner wavy wall of the spiral channel, is 340-960 μm.

[0013] Preferably, the depth of the spiral channel is 50-150 μm.

[0014] Preferably, the cross-section of the spiral channel is rectangular.

[0015] Preferably, the spiral channel has 4-9 turns.

[0016] Preferably, the channel layer includes a sample inlet located at the center of the spiral channel.

[0017] Preferably, the number of sample input ports is 1-2.

[0018] Preferably, the radius of curvature of the spiral channel at the sample inlet is 2-20 mm.

[0019] Preferably, the channel layer includes a separation collection area located at the end of the spiral channel.

[0020] Preferably, along the direction from the center to the end of the spiral channel, the separation and collection area includes a sudden expansion structure, an outlet channel, and an outlet connected in sequence.

[0021] Preferably, the abrupt expansion structure is a triangular structure with a height of 1-3 mm and a width of 500-2000 μm at its widest point.

[0022] Preferably, the number of outlet channels is 4-8.

[0023] Preferably, the width of the outlet channel is 50-150 μm and the length is 5-15 mm.

[0024] Preferably, the number of outlets is the same as the number of outlet channels.

[0025] Preferably, the outlet is circular in shape, and the diameter of the circle is 0.4-0.8 mm.

[0026] Preferably, the distance between two adjacent outlets is 0.4-1 cm.

[0027] Preferably, the chip further includes a substrate layer, and the substrate layer and the channel layer are bonded and packaged together.

[0028] A second aspect of this application is to provide a micro / nano particle separation device, the micro / nano particle separation device comprising: Microfluidic chip, wherein the microfluidic chip is the microfluidic chip described in one of the purposes; A fluid-driven system is used to deliver the sample to be separated into the microfluidic chip; And a detection system used to detect the separation of samples in the microfluidic chip.

[0029] Preferably, the fluid drive system includes a pressure pump and a flow sensor.

[0030] Preferably, the detection system is any one of an optical detection system, an electrical detection system, or a mass spectrometry detection system.

[0031] Technical features and beneficial effects of this utility model: This application utilizes an innovative asymmetric, wavy-walled spiral channel design to achieve a unique separation effect where small particles are positioned towards the inside and large particles towards the outside, breaking through the traditional separation mode of spiral chips. This microfluidic chip structure can achieve high-throughput, high-efficiency, continuous separation of particles such as microplastics without the need for external fields, and is simple to operate and low in cost. The separated particles can be directly interfaced with various analytical instruments, providing an efficient and reliable pretreatment solution for the size, composition, and content analysis of micro- and nano-particles such as microplastics. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the structural parameters of the corrugated wall in a specific implementation embodiment; Figure 2 This is a planar layout diagram of the channel layer structure in the microfluidic chip of Example 1; Figure 3 This is a schematic diagram of the microfluidic chip structure in a specific implementation method; Figure 4 This is a schematic diagram of the micro / nano particle separation device in a specific implementation embodiment; Figure 5 This is a diagram illustrating the particle separation effect of the micro / nano particle separation device in a specific implementation method. Explanation of the reference numerals in the attached figures: 1 is the sample inlet, 2 is the spiral channel, 3 is the sudden expansion structure, 4 is the outlet channel, 5 is the inner outlet, 6 is the first intermediate outlet, 7 is the second intermediate outlet, 8 is the third intermediate outlet, 9 is the fourth intermediate outlet, and 10 is the outer outlet. Detailed Implementation

[0033] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings. In the drawings, for clarity, the dimensions of layers, regions, and elements, as well as their relative dimensions, may be exaggerated. Throughout, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0034] It should be understood that when an element or layer is referred to as "on," "adjacent to," "connected to," or "coupled to" other elements or layers, it may be directly on, adjacent to, connected to, or coupled to other elements or layers, or there may be intervening elements or layers. Conversely, when an element is referred to as "directly on," "directly adjacent to," "directly connected to," or "directly coupled to" other elements or layers, there are no intervening elements or layers. It should be understood that although the terms first, second, third, etc., may be used to describe various elements, components, areas, layers, and / or portions, these elements, components, areas, layers, and / or portions should not be limited by these terms. These terms are only used to distinguish one element, component, area, layer, or portion from another element, component, area, layer, or portion. Therefore, without departing from the teachings of this application, the first element, component, area, layer, or portion discussed below may be referred to as a second element, component, area, layer, or portion. And the discussion of a second element, component, area, layer, or portion does not imply that the first element, component, area, layer, or portion necessarily exists in this application.

[0035] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0036] It should be noted that the terms "first," "second," etc., in the specification, claims, and accompanying drawings of this application are used to distinguish similar objects and are not necessarily used to describe a specific order or sequence. It should be understood that such terms can be used interchangeably where appropriate so that the embodiments of this application described herein can be implemented, for example, in orders other than those illustrated or described herein. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus.

[0037] In this application, when numerical intervals (i.e., numerical ranges) are involved, unless otherwise specified, the distribution of selectable numerical values ​​within the numerical interval is considered continuous, and includes the two endpoints of the numerical interval (i.e., the minimum and maximum values), as well as every numerical value between these two endpoints. Unless otherwise specified, when a numerical interval refers only to integers within that numerical interval, it includes the two endpoint integers of the numerical range, as well as every integer between the two endpoints, which is equivalent to directly listing every integer. When multiple numerical ranges are provided to describe features or characteristics, these numerical ranges can be merged. In other words, unless otherwise specified, the numerical ranges disclosed in this application should be understood to include any and all subranges included therein. The "numerical value" in the numerical interval can be any quantitative value, such as a number, percentage, ratio, etc. The term "numerical interval" can be broadly included to include percentage intervals, ratio intervals, proportion intervals, etc.

[0038] This application provides a technical solution for a microfluidic chip and a micro / nano particle separation device, as detailed below.

[0039] Exemplary embodiments according to this application will now be described in more detail with reference to the accompanying drawings. It should be understood that these exemplary embodiments may be implemented in many different forms and should not be construed as being limited to the embodiments set forth herein.

[0040] This application provides a microfluidic chip, which includes a channel layer; The channel layer is a spiral channel, and the spiral channel includes an inner wall and an outer wall; The inner wall is a flat wall, and the outer wall is a wavy wall.

[0041] It's important to note that microfluidics is a technology that precisely processes and manipulates tiny fluids within devices containing channels ranging from tens to hundreds of micrometers. It combines various technical units, such as pretreatment, separation, and detection, onto a chip measuring only a few square centimeters. Unlike macroscopic fluids, the fluids within microchannels exhibit extremely low Reynolds coefficients, displaying laminar flow, and their diffusion dynamics are highly controllable and predictable. The core of microfluidic technology is the microfluidic chip, which, through innovative design, enables simple, low-cost, and continuous separation and detection of particles.

[0042] This application utilizes an innovative asymmetric, wavy-walled spiral channel design to achieve a unique separation effect where small particles are positioned towards the inside and large particles towards the outside, breaking through the traditional separation mode of spiral chips. This microfluidic chip structure can achieve high-throughput, high-efficiency, continuous separation of particles such as microplastics without the need for external fields, and is simple to operate and low in cost. The separated particles can be directly interfaced with various analytical instruments, providing an efficient and reliable pretreatment solution for the size, composition, and content analysis of micro- and nano-particles such as microplastics.

[0043] The microfluidic chip used in this application introduces an asymmetric corrugated wall structure based on the traditional helical channel. The inner side of the channel is a flat wall, and the outer side is a corrugated wall. The waves themselves have alternating crests and troughs, and the water pressure at the crests and troughs is different, thus generating a pressure gradient in the horizontal and vertical directions. Particles are pushed from the high-pressure area to the low-pressure area, and the pressure gradient force points from the corrugated wall to the inner flat wall. Unlike the reported phenomenon in traditional helical chips (CN107084916B) where large particles flow out near the inner wall and small particles flow out near the outer wall, the experimental results using this microfluidic chip show that small particles flow out from the outlet channel near the inner wall and large particles flow out from the outer channel. This is because the particles in the channel are not only affected by the shear gradient and the inertial lift induced by the channel wall, and the secondary drag force of the fluid perpendicular to the main flow direction of the cross section, but also by the pressure gradient force induced by the corrugated wall. This causes the equilibrium position between the particles to shift and change. Influenced by the pressure gradient force, smaller particles exhibit better following behavior, resulting in greater migration perpendicular to the flow direction and gradually focusing towards the inner wall. Larger particles, due to their greater inertial lift, focus towards a relatively outer position in the channel, thus achieving the separation of microplastics of different sizes. By changing the channel parameters, wave amplitude, and wavelength, the equilibrium positions of particles of different sizes can be controlled, thereby achieving the separation of microplastics of different sizes. Furthermore, this can be extended to the separation of other micro- and nano-particles.

[0044] In some embodiments, the amplitude of the corrugated wall is A, the width of the spiral channel is B, and the ratio of A to B is (0.1-0.5):1, such as 0.1:1, 0.2:1, 0.3:1, 0.4:1, 0.5:1, etc.

[0045] In some embodiments, the wavelength of the corrugated wall is The width of the spiral channel is B. The ratio of B to B is (1-5):1, for example, 1:1, 2:1, 3:1, 4:1, 5:1, etc.

[0046] It should be noted that the amplitude A of the corrugated wall refers to the maximum offset distance of the corrugated wall relative to the centerline in the microchannel, which is a part of the channel width; the wavelength of the corrugated wall... It refers to the distance between two adjacent peaks or troughs (e.g. Figure 1 As shown), the periodic frequency of the wave-shaped wall is determined; the width B of the spiral channel refers to the average of the distance from the flat wall of the spiral channel to the wave crest and the distance from the flat wall to the wave trough within one period.

[0047] In some embodiments, with Figure 1 As shown, in the same channel, the distance from the flat wall to the corresponding wavy wall crest is W1, where W1 is 120-660 μm (e.g., 120 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 660 μm, etc.); the distance from the flat wall to the corresponding wavy wall trough is W2, where W2 is 80-500 μm (e.g., 80 μm, 100 μm, 150 μm, 200 μm, 250 μm, 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, etc.).

[0048] In some embodiments, with Figure 1 As shown, between adjacent channels, the distance from the outer flat wall of the spiral channel to the crest of the inner wavy wall of the spiral channel is W3, where W3 is 300-800 μm (e.g., 300 μm, 350 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, etc.); the distance from the outer flat wall of the spiral channel to the trough of the inner wavy wall of the spiral channel is W4, where W4 is 340-960 μm (e.g., 340 μm, 400 μm, 450 μm, 500 μm, 550 μm, 600 μm, 650 μm, 700 μm, 750 μm, 800 μm, 850 μm, 900 μm, 960 μm, etc.).

[0049] In some embodiments, the depth of the spiral channel is 50-150 μm, such as 50 μm, 70 μm, 80 μm, 100 μm, 120 μm, 150 μm, etc.

[0050] In some embodiments, the cross-section of the spiral channel is rectangular.

[0051] In some embodiments, the spiral channel has 4-9 turns, such as 4, 5, 6, 7, 8, or 9 turns.

[0052] In this application, the number of turns of the spiral channel is not specifically limited, and those skilled in the art can adjust it according to the actual situation.

[0053] In some embodiments, the channel layer includes a sample inlet located at the center of the spiral channel.

[0054] In some embodiments, the number of sample input ports is 1-2.

[0055] In some embodiments, the radius of curvature of the spiral channel at the sample inlet is 2-20 mm (e.g., 2 mm, 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, 18 mm, 20 mm, etc.).

[0056] In some embodiments, the channel layer includes a separation collection area located at the end of the spiral channel.

[0057] In some embodiments, along the direction from the center to the end of the spiral channel, the separation collection area includes a burst expansion structure, an outlet channel, and an outlet connected in sequence.

[0058] In some embodiments, the abrupt expansion structure is a triangular structure with a height of 1-3 mm (e.g., 1 mm, 2 mm, 3 mm, etc.) and a width of 500-2000 μm at its widest point (e.g., 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1000 μm, 1500 μm, 2000 μm, etc.).

[0059] In some embodiments, the number of exit channels is 4-8 (e.g., 4, 5, 6, 7, 8).

[0060] In some embodiments, the width of the outlet channel is 50-150 μm (e.g., 50 μm, 60 μm, 70 μm, 80 μm, 90 μm, 100 μm, 150 μm, etc.), and the length is 5-15 mm (e.g., 5 mm, 8 mm, 10 mm, 12 mm, 15 mm, etc.).

[0061] In some embodiments, the number of outlets is the same as the number of outlet channels.

[0062] In some embodiments, the outlet is circular in shape, and the diameter of the circle is 0.4-0.8 mm (e.g., 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, etc.). In some embodiments, the distance between two adjacent exits is 0.4-1 cm (e.g., 0.4 cm, 0.5 cm, 0.6 cm, 0.7 cm, 0.8 cm, 0.9 cm, 1 cm, etc.).

[0063] Example 1: A microfluidic chip The chip channel designed based on the inertial separation principle uses a spiral channel as the main body and introduces an asymmetric wavy wall structure, with a flat wall on the inner side and a wavy wall on the outer side; the cross-section of the spiral channel is rectangular; the channel layer includes a sample inlet, a spiral channel and a separation and collection area, which is located at the end of the spiral channel and includes a sudden expansion structure, an outlet channel and an outlet connected in sequence.

[0064] like Figure 2 As shown, the spiral channel 2 has 9 spiral turns, the wave amplitude (A) of the asymmetric corrugated wall structure is 20 μm, and the wavelength of the corrugated wall is ( The diameter of the spiral channel is 600 μm; the distance from the flat wall to the crest of the wavy wall (W1) is 190 μm, the distance from the flat wall to the trough of the wavy wall (W2) is 150 μm, the average channel width (B) is 170 μm, and the depth is 70 μm; between two adjacent channels, the distance from the flat wall to the crest of the wavy wall (W3) is 440 μm, and the distance from the flat wall to the trough of the wavy wall (W4) is 480 μm; there is one sample inlet 1 with an initial radius of curvature of 2 mm; the height of the abrupt expansion structure 3 is 2.3 mm, and the maximum width is 940 μm; the width of the outlet channel 4 is 70 μm, and the depth is 70 μm; the other end of the outlet channel 4 is connected to the outlet, which includes, from right to left: inner outlet 5, first middle outlet 6, second middle outlet 7, third middle outlet 8, fourth middle outlet 9, and outer outlet 10, with an outlet diameter of 0.5 mm and a distance of 0.5 cm between adjacent outlets.

[0065] like Figure 3 As shown, the substrate layer and the channel layer are bonded and encapsulated together. The material of the channel layer is polydimethylsiloxane (PDMS), and the material of the substrate layer is siliconized glass.

[0066] Example 2: A microfluidic chip The chip channel designed based on the inertial separation principle uses a spiral channel as the main body and introduces an asymmetric wavy wall structure, with a flat wall on the inner side and a wavy wall on the outer side; the cross-section of the spiral channel is rectangular; the channel layer includes a sample inlet, a spiral channel and a separation and collection area, which is located at the end of the spiral channel and includes a sudden expansion structure, an outlet channel and an outlet connected in sequence.

[0067] The spiral has 6 turns, the wave amplitude (A) of the asymmetric corrugated wall structure is 60 μm, and the wavelength of the corrugated wall is ( The average width of the channel is 300 μm and the depth is 80 μm. The distance from the flat wall to the crest of the wavy wall (W1) within the spiral channel is 360 μm, the distance from the flat wall to the trough of the wavy wall (W2) is 240 μm, the average channel width is 300 μm, and the depth is 80 μm. Between two adjacent channels, the distance from the flat wall to the crest of the wavy wall (W3) is 600 μm, and the distance from the flat wall to the trough of the wavy wall (W4) is 720 μm. There is one sample inlet with an initial radius of curvature of 5 mm. The height of the abrupt expansion structure is 2 mm, and the maximum width is 900 μm. The width of each outlet channel is 100 μm and the depth is 80 μm. There are five outlet channels with an outlet diameter of 0.5 mm and a distance of 0.4 cm between adjacent outlets.

[0068] The base layer and the channel layer are bonded and encapsulated together. The material of the channel layer is a cyclic olefin copolymer (COC), and the material of the base layer is a cyclic olefin copolymer (COC).

[0069] Example 3: A microfluidic chip The chip channel designed based on the inertial separation principle uses a spiral channel as the main body and introduces an asymmetric wavy wall structure, with a flat wall on the inner side and a wavy wall on the outer side; the cross-section of the spiral channel is rectangular; the channel layer includes a sample inlet, a spiral channel and a separation and collection area, which is located at the end of the spiral channel and includes a sudden expansion structure, an outlet channel and an outlet connected in sequence.

[0070] The spiral has 5 turns, the wave amplitude (A) of the asymmetric wave-shaped wall structure is 150 μm, and the wavelength of the wave-shaped wall is ( The diameter of the spiral channel is 1000 μm; the distance from the flat wall to the crest of the wavy wall (W1) is 650 μm, the distance from the flat wall to the trough of the wavy wall (W2) is 350 μm, the average channel width is 500 μm, and the depth is 120 μm; between two adjacent channels, the distance from the flat wall to the crest of the wavy wall (W3) is 660 μm, and the distance from the flat wall to the trough of the wavy wall (W4) is 960 μm; there are 2 sample inlets with an initial radius of curvature of 10 mm; the height of the abrupt expansion structure is 3 mm, and the maximum width is 1800 μm; the width of the outlet channels is 120 μm, and the depth is 120 μm; there are 8 outlet channels with an outlet diameter of 0.75 mm and a distance of 1 cm between adjacent outlets.

[0071] The substrate layer and the channel layer are bonded and encapsulated together. The channel layer is made of acrylic (PMMA), and the substrate layer is made of glass.

[0072] Example 4: Microfluidic Chip Fabrication Method The fabrication method of the microfluidic chip includes: after designing the structure of the microfluidic chip according to Example 1, drawing the graphics using AutoCAD software, designing the mold pattern of the microfluidic chip using Klayout software, and fabricating the mold based on standard soft lithography technology. After mold fabrication, polydimethylsiloxane (PDMS) prepolymer and curing agent are mixed uniformly at a mass ratio of 10:1 and subjected to vacuum degassing. The mixture is then filled into the mold and heated to 75 °C for curing. After demolding, a PDMS substrate with a specific microstructure is obtained. After perforation of the substrate, oxygen plasma cleaning is used to bond it to the surface of a clean glass slide, achieving a permanent seal. To enhance the bonding strength, the chip is heated at 120 °C for 120 min, finally obtaining a microfluidic chip for microplastic separation.

[0073] Example 5: A micro / nano particle separation device A micro / nano particle separation device includes a microfluidic chip, wherein the microfluidic chip is the microfluidic chip described above; A fluid-driven system is used to deliver the sample to be separated into the microfluidic chip; And a detection system used to detect the separation of samples in the microfluidic chip.

[0074] In some embodiments, the fluid drive system includes a pressure pump and a flow sensor; in some embodiments, the detection system is any one of an optical detection system, an electrical detection system, or a mass spectrometry detection system.

[0075] like Figure 4As shown, the micro / nano particle separation device includes a fluid system and an optical detection system. The fluid system mainly includes a pressure pump providing fluid driving force, a liquid storage tank, a flow sensor monitoring the fluid's operating status, a microfluidic chip for the main fluid channel, and connecting pipes for various fluid components. The optical detection system is a fluorescence microscope with a fluorescence excitation module, capable of exciting red, blue, and green light to magnify and detect the excited fluorescent particles. During the method validation phase, fluorescent microplastics of different sizes are used as samples to optimize experimental conditions. The microfluidic chip is installed directly below the objective lens of the fluorescence microscope. The fluid in the chip is controlled by software to adjust the pressure and flow rate of the fluid in the channel in real time. The particles within the channel are conveniently and quickly observed using the microscope software, and the experimental process is recorded in real time.

[0076] The working principle of the micro / nano particle separation device: The air compressor provides a pressure source for the pressure pump, which pushes the fluid in the reservoir into the capillary. A flow sensor is connected in series between the reservoir and the capillary of the microfluidic chip. The connection between the flow sensor and the pressure pump is used for negative feedback signal regulation to keep the flow rate within a stable range. The other end of the flow sensor is connected to the chip inlet. Fluids containing microplastics of different sizes are separated in the chip. The fluid movement process is recorded by a CCD microscope. Different outlets of the chip are connected to sample collectors.

[0077] The microfluidic chip prepared in Example 1 was applied to the aforementioned micro / nano particle separation device. Fluorescent microplastics of different sizes, such as polystyrene particles, were used as verification samples, including 7.5 μm red fluorescent polystyrene particles and 15 μm green fluorescent polystyrene particles, with a mass fraction of 100 mg / 10 mL for both types of microplastics. A mixed solution of microplastics of different sizes was prepared, diluted with pure water, and 0.1% Tween 20 was added. Tween 20 can prevent particle aggregation. The concentration of the 7.5 μm fluorescent particles was 3 × 10⁻⁶. 5 The concentration of fluorescent particles at 15 μm is 3 × 10⁻⁶ / mL. 4 The particle distribution at the channel exit was observed under bright-field and fluorescence-field microscope modes at a throughput of 200 μL / min. (e.g., particles / mL) Figure 5 As shown, under bright field conditions, small particles flow out from the first outlet, while large particles flow out from the second outlet. In fluorescence mode, red particle beams of 7.5 μm particles and green particle beams of 15 μm particles are observed to flow out from the first outlet, respectively. When combined, the fluorescence beams of the two particle sizes in the figure do not intersect at the outlet, achieving complete separation.

[0078] Similarly, applying the microfluidic chips prepared in Examples 2-3 to the above-mentioned micro / nano particle separation device can also achieve the separation of particles of different sizes.

[0079] This micro / nanoparticle separation device utilizes a microfluidic chip to separate microplastics from pre-treated environmental samples, while simultaneously employing fluorescence microscopy for detection. Microplastic samples of different sizes are collected at the end of the device and can then be analyzed using other instruments, such as a thermal analyzer-gas chromatography / mass spectrometry system, to obtain the pyrolysis product components of the microplastics. Chromatograms of specific decomposition products are screened to determine the composition and peak area of ​​characteristic components. A standard curve is used to obtain the absolute content of corresponding components, and the microplastic content is determined by analyzing the amount of characteristic components. Comprehensive analysis yields information on the size, abundance, composition, and content of microplastics in specific environmental samples. Furthermore, as a pretreatment separation system, this device can be combined with other detection techniques, such as MALDI-TOF-MS and Raman spectroscopy, to detect and analyze microplastics in the environment, in addition to thermal analysis.

[0080] It should be noted that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential," etc., are used only for the convenience of describing this application and simplifying the description, and 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 this application. The directional terms "inner" and "outer" refer to the inside or outside relative to the outline of the component itself. For example, if a device in the drawings is inverted, a device described as "above" or "on top of" other devices or structures will 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 are interpreted accordingly.

[0081] It should also be noted that the terms "one embodiment," "another embodiment," and "embodiment" used in this application refer to specific features, structures, or characteristics described in connection with that embodiment, which are included in at least one embodiment described in the general description of this application. The appearance of the same expression in multiple places in the specification does not necessarily refer to the same embodiment. Furthermore, when a specific feature, structure, or characteristic is described in connection with any embodiment, the intention is to suggest that implementing such a feature, structure, or characteristic in conjunction with other embodiments also falls within the scope of this application.

[0082] In the above embodiments, the descriptions of each embodiment have different focuses. For parts not described in detail in a certain embodiment, please refer to the relevant descriptions in other embodiments.

[0083] It should also be noted that the above are merely preferred embodiments of this application and do not limit the scope of patent protection of this application. Any equivalent structural or procedural changes made using the content of this application’s specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the scope of patent protection of this application.

Claims

1. A microfluidic chip, characterized in that, The microfluidic chip includes a channel layer; The channel layer is a spiral channel, and the spiral channel includes an inner wall and an outer wall; The inner wall is a flat wall, and the outer wall is a wavy wall.

2. The microfluidic chip according to claim 1, characterized in that, The ratio of the amplitude of the corrugated wall to the width of the spiral channel is (0.1-0.5):1; The ratio of the wavelength of the wave-shaped wall to the width of the spiral channel is (1-5):

1.

3. The microfluidic chip according to claim 1 or 2, characterized in that, In the spiral channel, the distance from the flat wall to the corresponding wave crest position of the wavy wall is 120-660 μm; The distance from the flat wall to the trough of the corresponding wavy wall is 80-500 μm.

4. The microfluidic chip according to claim 1 or 2, characterized in that, Between adjacent channels, the distance from the outer flat wall of the spiral channel to the crest of the inner wavy wall of the spiral channel is 300-800 μm. The distance from the outer flat wall of the spiral channel to the trough of the inner wavy wall of the spiral channel is 340-960 μm.

5. The microfluidic chip according to claim 1, characterized in that, The depth of the spiral channel is 50-150 μm; The cross-section of the spiral channel is rectangular; The spiral channel has 4-9 turns.

6. The microfluidic chip according to claim 1, characterized in that, The channel layer includes a sample inlet, which is located at the center of the spiral channel. The number of sample input ports is 1-2; The radius of curvature of the spiral channel at the sample inlet is 2-20 mm.

7. The microfluidic chip according to claim 1, characterized in that, The channel layer includes a separation collection area located at the end of the spiral channel; Along the direction from the center to the end of the spiral channel, the separation and collection area includes a sudden expansion structure, an outlet channel, and an outlet connected in sequence; The abrupt expansion structure is a triangular structure with a height of 1-3 mm and a width of 500-2000 μm at its widest point. The number of exit channels is 4-8; The width of the outlet channel is 50-150 μm and the length is 5-15 mm; The number of exits is the same as the number of exit channels; The outlet is circular in shape, and the diameter of the circle is 0.4-0.8 mm; The distance between two adjacent exits is 0.4-1 cm.

8. The microfluidic chip according to claim 1, characterized in that, The chip also includes a substrate layer; The base layer and the channel layer are bonded and encapsulated together.

9. A micro / nano particle separation device, characterized in that, The micro / nano particle separation device includes: A microfluidic chip, wherein the microfluidic chip is the microfluidic chip according to any one of claims 1-8; A fluid-driven system is used to deliver the sample to be separated into the microfluidic chip; And a detection system used to detect the separation of samples in the microfluidic chip.

10. The micro / nano particle separation device according to claim 9, characterized in that, The fluid drive system includes a pressure pump and a flow sensor; The detection system can be any one of an optical detection system, an electrical detection system, or a mass spectrometry detection system.

Images