A microfluidic device for studying nanoparticle transport across membranes

Abstract

The application provides a microfluidic device for studying nanoparticle transmembrane transport, and belongs to the technical field of microfluidic chips. A porous medium film is generated in a non-contact manner inside a microfluidic channel by using ultraviolet light curing technology, the temperature of the microfluidic channel is controlled by using silver-containing epoxy resin, and the refractive index of the opaque porous medium is adjusted by using a sucrose aqueous solution. The diffusion movement of particles can be measured by a single particle tracking method of fluorescence microscopic imaging, and a particle movement trajectory image is obtained after processing. Compared with other devices, the application has the advantages of simple structure, low cost, convenient operation, and can be applied to oil exploitation, functional polymer membranes, basic biomedical research and clinical rapid detection and the like.

Description

Technical Field

[0001] This invention belongs to the field of microfluidic chip technology, specifically relating to a microfluidic device for studying transmembrane transport of nanoparticles, that is, a microfluidic device for studying transmembrane transport of nanoparticles constructed based on microfluidic technology. Background Technology

[0002] Porous membranes, also known as porous media, are a class of materials containing pores (voids). The framework of the material is solid, while the pores are typically filled with liquid or gas. Porous media have a wide range of applications, from filtration membranes to bioreactors to heterogeneous catalysis. Furthermore, many geological and biological environments are porous. The transport of nanoparticles in porous media is a topic of broad significance in environmental science, polymer science, and biomedical applications, such as the diffusion and migration of nanoparticles in soil environments, the movement of nanoparticles in polymer membranes, and the delivery of nanomedicines in biological tissues. Exploring the transport mechanisms of nanoparticles in porous media is crucial for information transmission, drug delivery, oil extraction, groundwater recharge, and modeling studies of organ-on-a-chip systems.

[0003] Currently, microfluidic technology is widely used to build microfluidic models and conduct in-depth research on flow and transport phenomena in porous media due to its advantages such as low material consumption, low cost, and precise control and manipulation of fluid motion. To observe the internal conditions of porous structures, transparent soft materials are often used to prepare porous media, such as the following inventions: a method for fabricating personalized transparent silicone models based on soluble materials (application number: CN201811194119.1), and a 3D-printed interventional surgical model and fabrication method for visceral aneurysms (application number: CN202111420548.8). However, the framework materials of real-world porous media are generally opaque and structurally complex, making direct observation of their internal flow characteristics difficult and posing a significant challenge to research. To achieve visualized single-particle motion, refractive index matching of opaque porous media is required. However, most liquids used for refractive index matching are uncommon or compound-based and pose certain health risks, as illustrated in the following patents: a refractive index matching liquid (application number: CN201910247620.8) and an optical detection method for refractive index matching liquid and glass (application number: CN202110581473.5). Therefore, these methods have not been widely adopted. Furthermore, there is no universal model for predicting the transport of nanoparticles or macromolecules in porous media based on a simple description of the porous material. In recent years, advancements in nanoparticle tracking technology have enabled the reconstruction of single-particle trajectories with nanoscale spatial and millisecond temporal resolutions, providing detailed displacement information non-contactly for statistical analysis.

[0004] Based on this, this invention proposes a microfluidic device for studying transmembrane transport of nanoparticles. Specifically, it constructs a microfluidic device based on microfluidic technology, which prepares a porous medium inside a microfluidic channel and modulates the surrounding temperature. The porous medium is prepared using ultraviolet light curing technology, and a refractive index-matching fluid is used to perform refractive index matching on the opaque porous medium. Nanoparticle tracking technology is then used to measure the movement of nanoparticles within the porous medium. Summary of the Invention

[0005] This invention aims to provide a microfluidic device for the preparation of porous media in a temperature-controlled, contactless manner. The flow rate is adjusted by a flow pump, allowing the porous media solution to slowly flow along a micropillar array within the porous media formation channels until the channels are filled. A portable ultraviolet curing device is used to irradiate the solution to generate an opaque porous media structure. A sucrose aqueous solution is used to adjust the refractive index of the opaque porous media. A silver-containing epoxy resin is used to control the temperature of the microfluidic channels. The diffusion motion of nanoparticles in the porous media can be measured using single-particle tracking fluorescence microscopy.

[0006] In this invention, the device comprises a microfluidic chip, a temperature control system, and a porous medium. Compared to other simulation devices, this invention features highly conductive silver-containing epoxy resin symmetrically positioned on both sides of the porous medium, ensuring uniform and stable temperature; the porous medium is directly generated within the microchannel, avoiding potential contamination; a non-toxic, transparent sucrose aqueous solution matches the refractive index of the porous medium, making the movement of nanoparticles within it visible; and nanoparticle tracking technology provides detailed trajectory information non-contactly. Based on these four points, the device of this invention can achieve low-cost, pollution-free preparation of porous media and explore the transport of nanoparticles in porous media under different environments.

[0007] The technical solution of the present invention:

[0008] A microfluidic device for studying transmembrane transport of nanoparticles, the microfluidic device consisting of a microfluidic chip and a temperature control system.

[0009] The microfluidic chip includes a glass slide 1 and a PDMS substrate 2; the PDMS substrate 2 is adhered to the upper surface of the glass slide 1; the PDMS substrate 2 is etched with vertically arranged inlet holes a3, inlet holes b4, outlet holes a5 and b6, as well as horizontally arranged temperature control channels 7 and intermediate microfluidic channels 8, forming a symmetrical structure, wherein there are two inlet holes a3 and two outlet holes a5, each inlet hole a3 corresponds to one outlet hole a5, and there is one inlet hole b4 and one outlet hole b6, corresponding to each other.

[0010] The intermediate microfluidic channel 8 has a symmetrical structure with two rows of micropillar arrays 8-4 at its center. It is an integral structure with the PDMS substrate 2. The gap between the two rows of micropillar arrays 8-4 forms a porous medium forming channel 8-2. The two sides of the porous medium forming channel 8-2 are microfluidic channels a8-1 and b8-3, respectively. The two ends of microfluidic channel a8-1 are connected to one set of inlet holes a3 and outlet holes a5, respectively. The two ends of microfluidic channel b8-3 are connected to another set of inlet holes a3 and outlet holes a5, respectively. The two ends of the porous medium forming channel 8-2 are connected to inlet holes b4 and outlet holes b5, respectively. The inlet holes a3, b4, a5, and b5 all penetrate the entire PDMS substrate 2. An external conduit is inserted into the holes from the opening on the upper surface to input or output liquid.

[0011] There are two temperature control channels 7, which are symmetrically arranged on both sides of the middle microfluidic channel 8. The temperature control channel 7 is a U-shaped channel, with temperature control channel opening a7-3-1 and temperature control channel opening b7-3-2 at its two ends, respectively.

[0012] The temperature control system includes a silver-containing epoxy resin 7-1, a sliding rheostat 7-2 located outside the PDMS substrate 2, and a controllable DC voltage regulator 9. The silver-containing epoxy resin 7-1 fills the interior of the temperature control channel 7. On the upper surface of the PDMS substrate 2, wires are led out from the temperature control channel openings a7-3-1 and b7-3-2 on both sides of the central microfluidic channel 8 and connected together. The temperature control channel opening b7-3-2 is connected to the negative terminal of the controllable DC voltage regulator 9. The wires led out from the temperature control channel opening a7-3-1 are connected to one end of the sliding rheostat 7-2 and the other end is connected to the positive terminal of the controllable DC voltage regulator 9. The controllable DC voltage regulator 9 provides a stable DC operating voltage. The working principle of the temperature control circuit is as follows: the silver-containing epoxy resin 7-1 can be regarded as a resistor that can conduct heat and has a certain resistance. By adjusting the sliding rheostat 7-2, the voltage across the silver-containing epoxy resin 7-1 is changed, thereby affecting its temperature change. Based on this, the control of constant temperature and temperature change can be achieved in the model device.

[0013] Furthermore, the silver-containing epoxy resin 7-1 is made by mixing liquid metallic silver and epoxy resin in a mass ratio of 1:1 to 1:2. When the two are fully mixed and homogeneous, they can be used as a liquid material that is conductive and thermally conductive. After a period of time, the material can be solidified into a solid, which is symmetrically located on both sides of the central microfluidic channel 8 to achieve heating of the central microfluidic channel 8.

[0014] Furthermore, the microfluidic channels a8-1 and b8-3 have the same structure, both including serpentine channels and straight channels. One end of each serpentine channel is connected to both ends of the straight channel, and the other end of each serpentine channel is connected to the inlet hole a3 and the outlet hole a5, respectively. The serpentine channels and the porous medium forming channel 8-2 have a certain inclination angle. The serpentine channels adopt a serpentine loop, which helps to eliminate the shaking that occurs after the solution enters the channel. The total length of the straight channel is L1, the total length of the serpentine channel is L2, the width of both microfluidic channels a8-1 and b8-3 is W1, the width of the porous medium forming channel 8-2 is W2, and the total channel depth is H. L1, L2, W1, and W2 are in the centimeter range, and H is in the hundred-micrometer range.

[0015] Further, the process of forming a porous media film in the porous media forming channel 8-2 is as follows: air or an oil immiscible with the porous media, such as olive oil or mineral oil, is injected through the inlet hole a3. The air or the oil immiscible with the porous media is then introduced into microfluidic channels a8-1 and b8-3, respectively. Simultaneously, a porous media solution is injected through the inlet hole b4. Two rows of micropillar arrays 8-4 guide the porous media solution to flow along the porous media forming channel 8-2, while ensuring that it does not flow into microfluidic channels a8-1 or b8-3. Then, using ultraviolet light curing technology, the porous media solution forms an opaque porous media film in the porous media forming channel 8-2. The formation of a porous media film inside the microfluidic channel 8 avoids contamination of the porous media due to exposure to air. The porous media solution is a photocurable hydrogel solution, such as polyethylene glycol diacrylate (PEGDA) or methacrylic anhydride gelatin (GelMA).

[0016] Furthermore, in studying the transmembrane transport of nanoparticles, an aqueous solution of sucrose mixed with nanoparticles was injected into the inlet pore a3. The sucrose solution contained 10%–40% sucrose by mass, and the nanoparticles by volume had a volume fraction of 10%. -7 -10 -5 The nanoparticles, with diameters ranging from 200 to 500 nm, are visualized by adjusting their diameter within the channel. When a sucrose aqueous solution containing nanoparticles is injected into the inlet orifice a3, the flow rate is controlled by a flow pump, ensuring manageable flow.

[0017] Furthermore, the microfluidic device also includes a computer 10, a high-speed camera 11, a fluorescence microscope 12, and a flow pump 13. The flow pump 13 is connected to inlet holes a3 and b4 via external conduits to control the flow rate of the solution entering the microfluidic channel. The computer 10 is connected to the high-speed camera 11, and the high-speed camera 11 is connected to the fluorescence microscope 12, so that the specific phenomena can be directly observed on the computer monitor. The fluorescence microscope 12 is placed directly above the microfluidic chip. The fluorescence microscope 12 observes the transmembrane transport of nanoparticles in the porous medium film and transmits the observation results to the high-speed camera 11. The high-speed camera 11 transmits the captured images to the computer 10.

[0018] The beneficial effects of this invention are:

[0019] This invention provides a temperature- and flow-rate-controllable, porous, and opaque microfluidic device for studying transmembrane transport of nanoparticles. It ingeniously combines microfluidic technology and UV curing technology to directly generate porous media within the microfluidic channel, preventing contamination from air exposure. The device is cleverly designed and easy to operate. The silver-containing epoxy resin serves as both a heating element and a resistor, enabling stable temperature control. Simultaneously, a sucrose aqueous solution is used to match the refractive index of the opaque porous media. Combined with nanoparticle tracking technology, this allows direct visualization of nanoparticle movement within various porous materials, ranging from single-pore to macroscopic length scales. This invention has important applications in membrane fouling, groundwater recharge, oil extraction, basic biomedical research, and rapid clinical detection. Attached Figure Description

[0020] Figure 1 This is a structural diagram of the microfluidic device of the present invention for studying transmembrane transport of nanoparticles.

[0021] Figure 2 This is a top view of the microfluidic channel design.

[0022] Figure 3 This is a schematic diagram of the working principle of a temperature control system.

[0023] Figure 4 This is a diagram showing the trajectory of nanoparticles in a porous medium.

[0024] Figure 5 This is a schematic diagram of a simulation device used to study the transmembrane transport of nanoparticles.

[0025] In the figure: 1. Glass slide; 2. PDMS substrate; 3. Inlet hole a; 4. Inlet hole b; 5. Outlet hole a; 6. Outlet hole b; 7. Temperature control channel; 7-1. Silver-containing epoxy resin; 7-2. Sliding rheostat; 7-3-1. Temperature control channel opening a; 7-3-2. Temperature control channel opening b; 8. Intermediate microfluidic channel; 8-1. Microfluidic channel a; 8-2. Porous medium formation channel; 8-3. Microfluidic channel b; 8-4. Micropillar array; 9. Adjustable DC voltage regulator; 10. Computer; 11. High-speed camera; 12. Fluorescence microscope; 13. Flow pump. Detailed Implementation

[0026] The technical solution of the present invention will be further described below with reference to specific embodiments and accompanying drawings.

[0027] like Figure 1 As shown, this invention discloses a microfluidic device for studying transmembrane transport of nanoparticles. The microfluidic device includes a glass slide 1 and a PDMS substrate 2, with the PDMS substrate 2 bonded to the glass slide 1. The PDMS substrate 2 has inlet holes a3, b4, outlet holes a5, b6, a temperature control channel 7, and an intermediate microfluidic channel 8 etched inside. The temperature control channel 7 is arranged on both sides of the intermediate microfluidic channel 8, and silver-containing epoxy resin 7-1 is placed in the temperature control channel 7.

[0028] like Figure 2 As shown, the intermediate microfluidic channel 8 includes a microfluidic channel inlet, a serpentine channel, a straight channel, and a channel outlet connected in sequence; the straight channel is composed of a micropillar array 8-4, a microfluidic channel a8-1, a microfluidic channel b8-3, and a porous medium forming channel 8-2. The porous medium forming channel 8-2 is located between the microfluidic channel a8-1 and the microfluidic channel b8-3. The inlet hole a3, inlet hole b4, outlet hole a5, and outlet hole b2 are all circular holes with a diameter of 1 mm.

[0029] like Figure 3 As shown, the temperature control system includes a silver-containing epoxy resin 7-1, an adjustable DC voltage regulator 9, and a sliding rheostat 7-2. By adjusting the resistance of the sliding rheostat, the current in the control circuit is controlled, thereby changing the voltage drop across the silver-containing epoxy resin and achieving temperature control. The adjustable DC voltage regulator is an MS305D.

[0030] like Figure 4 As shown, the image depicts the trajectory of nanoparticles in a porous medium film, captured by a high-speed microscope.

[0031] During the encapsulation process, a plasma cleaner was used to bond the PDMS substrate 2 to the glass slide 1. After baking at 80°C for 1-2 hours, the PDMS substrate 2 and the glass slide 1 were firmly bonded together.

[0032] In this implementation example, a computer 10, a high-speed camera 11, a fluorescence microscope 12, and a flow pump 13 are also included, which together constitute a complete microfluidic simulation device for the controllable transmembrane transport environment of nanoparticles. Figure 5 ).

[0033] The specific steps for using the microfluidic device of the present invention for studying transmembrane transport of nanoparticles are as follows:

[0034] Porous media solution and air are introduced into the central microfluidic channel 8 through inlet holes b4 and a3, respectively. A flow pump 13 regulates the solution flow rate to ensure the solution fills the porous media forming channel without flowing into other channels. A portable UV curing device is positioned 5 cm above the microfluidic chip and irradiates for 2-3 minutes to solidify the porous media solution and form a porous membrane. Polystyrene particles with a particle size of 200 nm are mixed with a sucrose aqueous solution and added to inlet hole a3. The flow pump 13 regulates the solution flow rate. An adjustable DC voltage regulator 8 is turned on, and adjusting the voltage changes the current in the circuit. At this time, the silver-containing epoxy resin 7-1 is heated, creating different temperature environments. A computer 10, a high-speed camera 11, and a fluorescence microscope 12 are connected. When the flow rate and temperature are stable, the flow of nanoparticles is observed under transient conditions. The high-speed camera 11 acquires video images at a shooting rate of n frames per second, which can be observed and stored on the computer 10 screen. Using nanoparticle tracking technology, we extracted the trajectory information of nanoparticle motion using ImageJ and MATLAB, and performed extensive data processing and statistical analysis to obtain the desired results.

[0035] In this implementation, the microfluidic chip can be fabricated using standard soft lithography and laser engraving techniques. In the device structure made of polydimethylsiloxane (PDMS) material, a 100μm thick polyimide film with microfluidic channel structure is cut using a laser engraving machine and attached to a silicon wafer. The silicon wafer is placed in a glass dish, a prepared PDMS solution is poured in, and then it is left to stand in a vacuum for 20 minutes to remove air bubbles. It is then placed in a drying oven and baked at 80°C for 90 minutes to solidify the PDMS. Afterward, the glass dish is removed, and once the temperature has cooled, the PMDS is separated from the mold to obtain PMDS with a microfluidic channel structure. Cut off the PDMS containing the microfluidic channels to be used, and use a punch to open the channel inlet and outlet. After cleaning, bond the PDMS to a clean glass slide with a thickness of about 1.1 mm using a plasma cleaner. Heat at 120°C for 15-20 minutes to make the adhesion more stable. Then, insert the conduit into the hole drilled on the chip, and apply glue evenly at the junction of the conduit and the hole to prevent leakage. After applying glue, place the chip in a drying oven and bake at 80°C overnight. Finally, connect the conduit and the flow pump together. This completes the fabrication of the device.

[0036] Microfluidic chip design such as Figure 1 and Figure 2 As shown: the thickness of PDMS substrate 2 is 0.8-1cm, the straight channel length L1 = 2.5cm, the serpentine channel length L2 = 12.5cm, the angle is 45 degrees, the width of microfluidic channel a8-1 and microfluidic channel b8-3 is W1 = 450μm, the width of porous medium forming channel 8-2 is W2 = 100μm, and the height of the entire channel is H = 100μm.

[0037] In this embodiment, silver-containing epoxy resin 7-1 is introduced into the temperature control channel 7, and a wire is led out from the temperature control channel openings a7-3-1 and b7-3-2 at both ends for connection. The temperature control circuit is designed as follows: Figure 3 As shown, the controllable DC voltage regulator 9 provides a stable DC operating voltage. One end of the sliding rheostat 7-2 is connected to the negative terminal of the controllable DC voltage regulator 9, and the other end is connected to the wire leading out from the temperature control channel opening a7-3-1. By adjusting the voltage of the controllable DC voltage regulator 8, the current in the circuit is changed, thereby heating the silver-containing epoxy resin 7-1 to achieve different temperature environments.

[0038] In this embodiment, a sucrose aqueous solution containing nanoparticles is added to the inlet straight conduit a3. The temperature control system is activated, and the device begins operation. The flow rate is adjusted by the flow pump 13. Once the flow rate and temperature stabilize, a high-speed camera 11 records the trajectory of the nanoparticles within the stable region. Nanoparticle tracking technology and statistical analysis techniques are used to analyze the trajectory of the nanoparticles, thus constructing a microfluidic simulation device for studying transmembrane transport of nanoparticles. This invention can simulate different flow rates, different porous structures, and different temperatures, enabling the tracking and recording of the transport process of nanoparticles in porous media.

[0039] This invention provides a temperature-controlled, flow-rate-controlled, porous, and opaque microfluidic device for studying transmembrane transport of nanoparticles. It features an ingenious design and low cost. The porous medium is generated directly within the microfluidic channel, preventing contamination. A silver-containing epoxy resin and temperature control circuit within the temperature control channel control the temperature environment surrounding the porous medium. Simultaneously, a transparent, non-toxic sucrose aqueous solution is used to adjust the refractive index of the opaque porous medium, enabling visualization. Furthermore, nanoparticle tracking technology is used to measure the trajectory of nanoparticles within the porous medium. This device can be applied to functional polymer membranes, porous underground environments, and biomedical research.

Claims

1. A microfluidic device for studying transmembrane transport of nanoparticles, characterized in that, The microfluidic device consists of a microfluidic chip and a temperature control system; The microfluidic chip includes a glass slide (1) and a PDMS substrate (2); the PDMS substrate (2) is attached to the upper surface of the glass slide (1); the PDMS substrate (2) is etched with vertically arranged inlet holes a (3), inlet holes b (4), outlet holes a (5) and outlet holes b (6), as well as horizontally arranged temperature control channels (7) and intermediate microfluidic channels (8), forming a symmetrical structure, wherein there are two inlet holes a (3) and two outlet holes a (5), each inlet hole a (3) corresponds to one outlet hole a (5), and there is one inlet hole b (4) and one outlet hole b (6), with the inlet hole b (4) corresponding to the outlet hole b (6); The intermediate microfluidic channel (8) has a symmetrical structure with two rows of micropillar arrays (8-4) at its center. It is an integral structure with the PDMS substrate (2). The gap between the two rows of micropillar arrays (8-4) forms a porous medium forming channel (8-2). The two sides of the porous medium forming channel (8-2) are microfluidic channel a (8-1) and microfluidic channel b (8-3), respectively. The two ends of microfluidic channel a (8-1) are respectively connected to one of the inlet holes a (3) and the outlet hole a (8-3). The inlet hole a (5) is connected, and the two ends of the microfluidic channel b (8-3) are connected to another set of inlet holes a (3) and outlet holes a (5) respectively. The two ends of the porous medium forming channel (8-2) are connected to inlet holes b (4) and outlet holes b5 respectively. The inlet holes a (3), inlet holes b (4), outlet holes a (5) and outlet holes b5 all penetrate the entire PDMS substrate (2). The external conduit is inserted into the hole from the opening on the upper surface to input or output liquid. There are two temperature control channels (7), which are symmetrically arranged on both sides of the middle microfluidic channel (8); the temperature control channel (7) is a U-shaped channel, with temperature control channel opening a (7-3-1) and temperature control channel opening b (7-3-2) at its two ends respectively. The temperature control system includes a silver-containing epoxy resin (7-1), a sliding rheostat (7-2) located outside the PDMS substrate (2), and a controllable DC voltage regulator (9). The silver-containing epoxy resin (7-1) fills the interior of the temperature control channel (7). On the upper surface of the PDMS substrate (2), wires are led out from the temperature control channel openings a (7-3-1) and b (7-3-2) on both sides of the central microfluidic channel (8) and connected together. The temperature control channel opening b (7-3-2) is connected to the negative terminal of the controllable DC voltage regulator (9). The wires led out from the temperature control channel opening a (7-3-1) are connected to one end of the sliding rheostat (7-2) and the other end is connected to the positive terminal of the controllable DC voltage regulator (9). The controllable DC voltage regulator (9) provides a stable DC operating voltage. The microfluidic channels a (8-1) and b (8-3) have the same structure, both including a serpentine channel and a straight channel. One end of the two serpentine channels is connected to both ends of the straight channel, and the other end of the two serpentine channels is connected to the inlet hole a (3) and the outlet hole a (5), respectively. The serpentine channel and the porous medium forming channel (8-2) have a certain inclination angle. The total length of the straight channel is L1, the total length of the serpentine channel is L2, the width of the microfluidic channels a (8-1) and b (8-3) is W1, the width of the porous medium forming channel (8-2) is W2, the total channel depth is H, L1, L2, W1 and W2 are in the centimeter range, and H is in the hundred-micrometer range.

2. The microfluidic device for studying transmembrane transport of nanoparticles according to claim 1, characterized in that, Silver-containing epoxy resin (7-1) is made by mixing liquid metallic silver and epoxy resin in a mass ratio of 1:1 to 1:

2.

3. A microfluidic device for studying transmembrane transport of nanoparticles according to claim 1 or 2, characterized in that, The process of forming a porous medium film in the porous medium forming channel (8-2) is as follows: air or oil immiscible with the porous medium is injected through the inlet hole a (3), and the air or oil immiscible with the porous medium is introduced into the microfluidic channel a (8-1) and the microfluidic channel b (8-3) respectively; at the same time, a porous medium solution is injected through the inlet hole b (4), and two rows of microcolumn arrays (8-4) guide the porous medium solution to flow along the porous medium forming channel (8-2), while ensuring that it does not flow into the microfluidic channel a (8-1) or the microfluidic channel b (8-3); then, through ultraviolet curing technology, the porous medium solution forms an opaque porous medium film in the porous medium forming channel (8-2).

4. A microfluidic device for studying transmembrane transport of nanoparticles according to claim 3, characterized in that, The porous medium solution is a photocurable hydrogel solution, which is polyethylene glycol (diol) diacrylate or methacrylic anhydride gelatin.

5. A microfluidic device for studying transmembrane transport of nanoparticles according to claim 1, 2, or 4, characterized in that, When studying the transmembrane transport of nanoparticles, an aqueous solution of sucrose mixed with nanoparticles was injected into the inlet pore a(3). The mass fraction of sucrose in the aqueous solution was 10%~40%, and the volume fraction of nanoparticles in the aqueous solution was 10%. -7 -10 -5 The diameter of the nanoparticles is 200-500 nm, and their movement in the channel can be visualized by adjusting the diameter of the nanoparticles.

6. A microfluidic device for studying transmembrane transport of nanoparticles according to claim 1, 2, or 4, characterized in that, The microfluidic device also includes a computer (10), a high-speed camera (11), a fluorescence microscope (12), and a flow pump (13). The flow pump (13) is connected to inlet hole a (3) and inlet hole b (4) through external conduits to control the flow rate of the solution entering the microfluidic channel. The computer (10) is connected to the high-speed camera (11), and the high-speed camera (11) is connected to the fluorescence microscope (12) so that the specific phenomena can be directly viewed on the computer monitor. The fluorescence microscope (12) is placed directly above the microfluidic chip. A fluorescence microscope (12) was used to observe the transmembrane transport of nanoparticles in a porous medium film. The observation results were transmitted to a high-speed camera (11), which then transmitted the captured images to a computer (10).

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