A 3D Microfluidic Multiphase Flow Displacement Visualization System Based on Laser Confocal Focusing

Abstract

This invention discloses a three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy, belonging to the field of multiphase flow displacement visualization systems. The system includes a three-dimensional microfluidic chip, a fluid injection system, a laser confocal microscopy observation system, and a data processing system. The three-dimensional microfluidic chip is fabricated by 3D printing based on real core CT scan data, after reconstruction and optimization, retaining real pore throat characteristics and adapting to standard interfaces. The fluid injection system stably delivers the displacement medium, the laser confocal microscopy observation system achieves high-resolution real-time three-dimensional imaging, and the data processing system completes image reconstruction and quantitative analysis of displacement efficiency. This system overcomes the limitations of traditional models and observations, accurately reproduces the real reservoir seepage characteristics, and can track multiphase flow dynamics in real time, providing reliable data support for the study of tertiary oil recovery displacement mechanisms and scheme optimization.

Description

Technical Field

[0001] This invention relates to the field of multiphase flow displacement visualization systems, specifically a three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy. Background Technology

[0002] During oil and gas field development, as primary and secondary oil recovery progress, easily accessible crude oil in the reservoir is gradually produced, leaving a large amount of crude oil as residual oil in the complex porous medium, leading to a decrease in recovery rate. To further improve recovery rate, tertiary oil recovery methods are commonly used, such as polymer flooding, surfactant flooding, and carbon dioxide flooding. These methods utilize the remaining crude oil by changing the properties of the injected fluid, reducing interfacial tension, improving the mobility ratio of the displacing fluid, or adjusting wettability. However, due to the extremely complex pore structure of oil reservoirs, fluid migration and interfacial changes in the pore throat are difficult to observe directly, and the study of displacement mechanisms has always been a technical bottleneck in the field of enhanced oil recovery.

[0003] Chinese patent CN120213734A discloses a three-dimensional microfluidic chip with multiple fluid inlets and pressure testing channels, which allows for real-time observation of the dynamic changes of the multiphase fluid interface under different vibration frequencies and amplitudes using a high-speed camera. However, the "three-dimensional" microfluidic chip used is usually based on an idealized geometric design and fails to be combined with CT scan data from real rock cores, thus lacking a high-fidelity reproduction of the real reservoir pore structure.

[0004] Chinese patent CN120721590A discloses a three-dimensional visualization device using layered visualization microbeads, which simulates heterogeneous strata by stacking microbeads with different permeabilities. However, this type of model is based on an idealized particle packing structure, which is fundamentally different from the complex three-dimensional pore network structure of real rock cores. At the same time, its observation methods are usually limited to macroscopic or two-dimensional surface observation, which cannot obtain the three-dimensional dynamic distribution information of fluid inside the pores, and it lacks the ability to quantitatively analyze key seepage parameters, making it difficult to accurately reveal the microscopic displacement mechanism.

[0005] The shortcomings of existing technologies are mainly reflected in the following aspects:

[0006] Limitations of Two-Dimensional Microfluidic Models. Existing microfluidic devices commonly used in research are mostly planar two-dimensional channels, with pore networks typically constructed based on ideal geometric designs or two-dimensional thin-section images. These two-dimensional models cannot accurately reflect the three-dimensional pore-throat connectivity, pore size distribution, and complex spatial topology of real reservoir cores, leading to significant discrepancies between experimental results and actual reservoir conditions, making it difficult to effectively guide in-situ displacement design.

[0007] Three-dimensional visualization imaging technology is insufficient. Current observations of displacement processes mainly rely on ordinary optical microscopy or two-photon microscopy, which have significant limitations in terms of penetration depth, resolution, and real-time three-dimensional reconstruction. Ordinary microscopes cannot capture fluid dynamics within deep channels; while two-photon microscopy can observe three-dimensional structures to some extent, it is slow, complex, and costly, making it unsuitable for continuous dynamic observation.

[0008] Model fabrication technology is immature. Some studies have attempted to use 3D printing to construct pore models, but these have mostly focused on simplifying the geometry and have failed to perform digital reconstruction based on real core data. Furthermore, the printing accuracy and transparency are insufficient to meet the needs of microscale fluid visualization. Simultaneously, the lack of a unified interface and packaging process makes it difficult to interface with experimental platforms such as fluid injection systems and confocal microscopes.

[0009] Real-time analysis of multiphase flow displacement cannot be achieved. During multiphase flow displacement, the interactions between fluids such as water, oil, and chemicals are complex, and interfacial tension and wetting states change significantly. Existing methods struggle to achieve real-time, continuous three-dimensional dynamic imaging and quantitative analysis at the micrometer level, failing to fully reveal the intrinsic mechanisms of residual oil formation and distribution. Summary of the Invention

[0010] The purpose of this invention is to provide a three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy, so as to solve the defects mentioned in the background art.

[0011] To achieve the above objectives, a three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy is provided, comprising a three-dimensional microfluidic chip, a fluid injection system, a laser confocal microscopy observation system, and a data processing system.

[0012] The fabrication process of the three-dimensional microfluidic chip includes:

[0013] S1. Select representative core samples from the reservoir and use either high-resolution CT or μCT to obtain three-dimensional volume data of the pore throat spatial structure. Reconstruct the three-dimensional pore network through threshold segmentation and region growing algorithm.

[0014] S2. Perform geometric smoothing and local size optimization on the three-dimensional pore network in CAD software to preserve the true pore size distribution and pore throat connectivity. At the same time, design standardized fluid inlet and outlet and observation windows at both ends of the model.

[0015] S3. Using either photopolymerization or two-photon polymerization 3D printing technology, a chip preform is printed using highly transparent photosensitive resin as the material. After support removal, cleaning, secondary curing, and surface wettability adjustment, a transparent substrate is completed.

[0016] S4. The printed three-dimensional porous network is plasma-bonded to a transparent substrate or encapsulated with a fluorescent adhesive that is not excited by laser, and a standard microfluidic interface is installed to achieve rapid connection with fluid injection systems, pressure sensors and imaging systems.

[0017] The fluid injection system includes a micro-injection pump, connecting pipelines and a pressure sensor. It is sealed and connected to the three-dimensional microfluidic chip through the standardized microfluidic interface and is used to stably inject the displacement medium into the chip.

[0018] The laser confocal observation system includes a laser confocal microscope platform, a laser source, and rapid scanning and three-dimensional reconstruction software. The three-dimensional microfluidic chip is fixed on the microscope platform. The laser emitted by the laser source enables high-resolution optical slicing. Combined with fluorescent labeling or optical contrast methods, the multiphase fluid interface is tracked, and three-dimensional image data of the displacement process is acquired in real time.

[0019] The data processing system includes a time-series 3D reconstruction module and a quantitative analysis module. The time-series 3D reconstruction module continuously reconstructs the acquired 3D image data, and the quantitative analysis module calculates the remaining oil saturation, fluid connectivity, pore volume utilization rate, and seepage channel evolution based on the reconstructed data to achieve a quantitative evaluation of displacement efficiency.

[0020] Furthermore, the displacement medium includes at least one of water, polymer solution, surfactant solution, and carbon dioxide.

[0021] Furthermore, in S4, the adhesive encapsulation adopts a three-dimensional porous structure and is mated with a 1mm thick optical-grade glass substrate, and is bonded after surface activation using oxygen plasma; the periphery is sealed with UV adhesive, and the curing time is 5 minutes; Luer threaded microfluidic connectors are assembled at the inlet and outlet to connect to either PEEK or PTFE microtubes.

[0022] Furthermore, the parameters for the quantitative evaluation of displacement efficiency also include two-dimensional classification of contact ratio, aspect ratio, shape factor, and Euler number.

[0023] Furthermore, according to claim 1, the three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy is characterized in that: the contact ratio formula is:

[0024]

[0025] In the formula, A contact The actual contact area between oil and rock (μm) 2 A total The total surface area of ​​the remaining oil (μm) 2 );

[0026] The aspect ratio formula is:

[0027]

[0028] In the formula, L max The longest principal axis length (μm) determined by principal component analysis; L min The shortest spindle length (μm);

[0029] The shape factor formula is:

[0030]

[0031] In the formula, S is the surface area of ​​a single oil droplet, in μm. 2 V represents the volume of a single oil droplet, in μm³.

[0032] The Euler number formula is:

[0033]

[0034] In the formula, V is the number of vertices; E is the number of edges; F is the number of faces; and C is the number of voxels.

[0035] Furthermore, the surface wettability control of S3 specifically involves: treating the chip channel surface with a silanizing agent to make the surface hydrophobic, which is used to simulate an oil-wet reservoir; or maintaining the original hydrophilic state of the surface to simulate a water-wet reservoir.

[0036] Furthermore, in S2, the optimized three-dimensional pore network has a minimum pore size of ≥15μm, the inlet and outlet flow channel diameters at both ends of the model are 0.5~1mm, and a fixed support frame is provided around the model to adapt to the packaging process and the installation of the laser confocal microscope stage.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] The chip's pore network is directly derived from CT scans of real rock cores. Through digital reconstruction and geometric optimization, the spatial connectivity, pore size distribution, and heterogeneity of pore throats are preserved to the maximum extent. This effectively overcomes the shortcomings of simplified two-dimensional models that cannot reflect the complexity of actual reservoirs, making experimental results closer to the seepage characteristics of real oil reservoirs.

[0039] Combining laser confocal microscopy enables high-speed optical slicing and 3D reconstruction, with observation depth and resolution far exceeding that of ordinary microscopes. It can track the oil-water interface, residual oil formation, and multiphase flow migration in real time. Real-time imaging can continuously record the entire displacement process, providing reliable data for dynamic analysis of displacement mechanisms.

[0040] Utilizing SLA photopolymerization or two-photon polymerization printing processes, resolutions below 10μm can be achieved, resulting in chips with excellent geometric accuracy and light transmittance. Post-printing processing and surface conditioning further ensure unobstructed channels and controllable wetting conditions, providing flexibility for various experimental simulations.

[0041] The standardized chip interface facilitates rapid connection to injection pumps, pressure control systems, and microscopic imaging platforms. Experimental conditions (pore structure, wettability, type of displacing fluid, and injection rate) are repeatable and controllable, ensuring consistency across different batches of experiments.

[0042] Three-dimensional time-series images obtained through confocal microscopy can be used to quantitatively calculate pore volume utilization, residual oil saturation, fluid connectivity, and seepage channel evolution. This allows for a direct comparison of the displacement efficiency and mechanisms under different tertiary oil recovery methods, such as waterflooding, polymer flooding, surfactant flooding, and CO2 flooding, providing data support for optimizing oilfield development strategies. Attached Figure Description

[0043] Figure 1 This is a flowchart of a specific implementation plan for a three-dimensional microfluidic multiphase flow displacement visualization system based on real-time laser confocal observation.

[0044] Figure 2 It is a laser confocal real-time observation visualization system for multiphase flow displacement of three-dimensional microfluidic chips;

[0045] Figure 3 This is a schematic diagram of a CT scan core slice. Detailed Implementation

[0046] Please see Figure 1-3 This invention provides a technical solution: a three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy, comprising a three-dimensional microfluidic chip, a fluid injection system, a laser confocal microscopy observation system, and a data processing system.

[0047] The fabrication process of a three-dimensional microfluidic chip includes:

[0048] S1. Select representative core samples from the reservoir and use either high-resolution CT or μCT to obtain three-dimensional volume data of the pore throat spatial structure. Reconstruct the three-dimensional pore network through threshold segmentation and region growing algorithm.

[0049] S2. Perform geometric smoothing and local size optimization on the three-dimensional pore network in CAD software to preserve the true pore size distribution and pore throat connectivity. At the same time, design standardized fluid inlet and outlet and observation windows at both ends of the model.

[0050] S3. Using either photopolymerization or two-photon polymerization 3D printing technology, a chip preform is printed using highly transparent photosensitive resin as the material. After support removal, cleaning, secondary curing, and surface wettability adjustment, a transparent substrate is completed.

[0051] S4. The printed three-dimensional porous network is plasma-bonded to a transparent substrate or encapsulated with a fluorescent adhesive that is not excited by laser, and a standard microfluidic interface is installed to achieve rapid connection with fluid injection systems, pressure sensors and imaging systems.

[0052] The fluid injection system includes a micro-injection pump, connecting tubing, and a pressure sensor. It is sealed and connected to a three-dimensional microfluidic chip through a standardized microfluidic interface and is used to stably inject displacement media into the chip.

[0053] The laser confocal observation system includes a laser confocal microscope platform, a laser source, and rapid scanning and 3D reconstruction software. The 3D microfluidic chip is fixed on the microscope platform. The laser emitted by the laser source enables high-resolution optical slicing. Combined with fluorescent labeling or optical contrast methods, the multiphase fluid interface is tracked, and 3D image data of the displacement process is acquired in real time.

[0054] The data processing system includes a time-series 3D reconstruction module and a quantitative analysis module. The time-series 3D reconstruction module continuously reconstructs the acquired 3D image data, while the quantitative analysis module calculates the remaining oil saturation, fluid connectivity, pore volume utilization rate, and seepage channel evolution based on the reconstructed data, thereby achieving a quantitative evaluation of displacement efficiency.

[0055] The displacement medium includes at least one of water, polymer solution, surfactant solution, and carbon dioxide.

[0056] The S4 adhesive encapsulation uses a three-dimensional porous structure to interface with a 1mm thick optical-grade glass substrate, and is bonded after surface activation using oxygen plasma; the outer periphery is sealed with UV adhesive, with a curing time of 5 minutes; Luer threaded microfluidic connectors are assembled at the inlet and outlet to connect to either PEEK or PTFE microtubes.

[0057] The parameters for quantitative evaluation of displacement efficiency also include two-dimensional classification of contact ratio, aspect ratio, shape factor, and Euler number.

[0058] The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 1 is characterized in that: the contact ratio formula is:

[0059]

[0060] In the formula, A contact The actual contact area between oil and rock (μm) 2 A totalThe total surface area of ​​the remaining oil (μm) 2 );

[0061] The aspect ratio formula is:

[0062]

[0063] In the formula, L max The longest principal axis length (μm) determined by principal component analysis; L min The shortest spindle length (μm);

[0064] The shape factor formula is:

[0065]

[0066] In the formula, S is the surface area of ​​a single oil droplet, in μm. 2 V represents the volume of a single oil droplet, in μm³.

[0067] The Euler number formula is:

[0068]

[0069] In the formula, V is the number of vertices; E is the number of edges; F is the number of faces; and C is the number of voxels.

[0070] The surface wettability control of S3 is specifically achieved by: treating the chip channel surface with a silanizing agent to make the surface hydrophobic, which is used to simulate an oil-wet reservoir; or maintaining the original hydrophilic state of the surface to simulate a water-wet reservoir.

[0071] The optimized three-dimensional pore network in S2 has a minimum pore size of ≥15μm, and the inlet and outlet flow channel diameters at both ends of the model are 0.5~1mm. The model is also equipped with a fixed support frame to adapt to the packaging process and the installation of the stage of the laser confocal microscope.

[0072] Example 1:

[0073] Core 3D Data Acquisition: A representative sandstone core cylindrical sample (25 mm in diameter, 40 mm in height) from an oilfield was selected, naturally dried, and then subjected to CT scanning. The scanning resolution was set to 2 μm / voxel, voltage 80 kV, current 100 μA, and rotation step size 0.2°. After scanning, complete 3D volumetric data was obtained in TIFF or RAW format with a resolution of approximately 2000 × 2000 × 2000 voxels.

[0074] Data reconstruction and digital modeling: Scanning data was imported using Avizo software, and Gaussian filtering was performed to denoise and enhance the contrast of the rock matrix and pores. Pore space was extracted using threshold segmentation and region growing algorithms to eliminate non-connected dead pores. The minimum pore diameter was appropriately enlarged to ≥15μm according to the subsequent printing accuracy to avoid printing failure or blockage. Inlet and outlet channels with a diameter of 0.5~1mm were designed at both ends of the model to facilitate connection to the standard Luer interface. A fixed support frame was added to the periphery of the model according to experimental requirements to ensure encapsulation and microscope compatibility.

[0075] High-precision 3D printing and post-processing: Printer: SLA photopolymerization 3D printer; Material: High-transparency photosensitive resin; Printing parameters: Layer thickness 25μm, standard photopolymerization energy setting, printing time approximately 6-8 hours;

[0076] Post-treatment: Clean with isopropanol for 10 minutes to remove residual resin; perform secondary UV curing for 30 minutes to enhance mechanical strength; purge the channels with low-pressure air to ensure unobstructed flow; perform surface plasma treatment on the flow channels (20W, 60s) to enhance encapsulation bonding. Surface wettability can be adjusted according to experimental simulation needs: for example, treating the surface with a silanizing agent to make it hydrophobic, simulating an oil-wet reservoir.

[0077] Chip packaging and interface installation: The printed three-dimensional porous structure is mated with a 1mm thick optical-grade glass substrate, and bonded after surface activation using oxygen plasma (50W, 90s); the periphery is sealed with UV adhesive and cured for 5 minutes; Luer threaded microfluidic connectors are assembled at the inlet and outlet to connect PEEK or PTFE microtubes; standard fixtures or sockets are designed on the outside of the chip to fix it on the stage of a laser confocal microscope.

[0078] Water flooding experiment and real-time confocal microscopy observation: Formation crude oil or simulated formation crude oil was injected into the chip to ensure full pore coverage; a displacing fluid was injected at a constant flow rate of 0.5 μL / min using an injection pump to control the smooth advancement of the displacement front; laser confocal microscope parameters: excitation wavelength 543 nm, fluorescence emission range 560-650 nm, Z-axis scanning step 2 μm; three-dimensional data of the displacement process were continuously acquired, and the stack image was updated every 3 seconds until steady state. Oil-water distribution was reconstructed using image analysis software (Leica confocal offline software LASX and ImageJ+3DViewer plugin), and the remaining oil saturation and displacement efficiency were calculated.

[0079] Three-dimensional microscopic residual oil statistics: The occurrence of microscopic residual oil in three dimensions is complex, requiring a combination of two-dimensional classification standards and the introduction of parameters such as contact ratio, aspect ratio, shape factor, and Euler number for multi-faceted analysis to define a three-dimensional microscopic residual oil classification standard. First, the contact between residual oil clumps and rock is observed. The contact area ratio refers to the proportion of the contact area between residual oil and rock particles to their total surface area, reflecting the interfacial bonding strength between oil droplets and rock. If an oil globule is completely encased in rock, the contact area ratio is recorded as 1; if the oil globule is completely surrounded by water and does not contact the rock at all, the ratio is recorded as 0. This helps determine whether the oil globule is "trapped" by the rock or "floating" in the pores. Next, the shape characteristics of the oil globule need to be measured. The aspect ratio is the ratio of the longest principal axis length to the shortest principal axis length of the three-dimensional morphology of the residual oil, characterizing its extensibility or flatness. At the same time, a new shape factor parameter is further defined for the classification of three-dimensional microscopic residual oil. The shape factor describes the complexity of the oil globule's shape. A new shape factor parameter is defined based on the two-dimensional microscopic residual oil classification standard. When other parameters conflict, the shape factor will be used as the main discrimination criterion. Finally, the integrity of the oil globule is checked by the Euler number. The Euler number is a parameter that describes the topological connectivity of a three-dimensional object. Oil globules with intact structures and no breaks or holes have higher values, while oil globules that are broken, split, or have internal cavities will have lower values.

[0080] By combining parameters such as contact ratio, aspect ratio, shape factor, and Euler number, specific three-dimensional microscopic residual oil classification standards are formulated, enabling statistical and spatial characterization of the three-dimensional microscopic residual oil occurrence characteristics. This method combines the location, shape, and structural characteristics of oil clusters, providing a more comprehensive approach than traditional single indicators and enabling more precise guidance for oilfield development. Specific classification standards are shown in Table 1.

[0081] Table 1. Classification of Microscopic Residual Oil

[0082] .

Claims

1. A three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal focusing, characterized in that, Includes a 3D microfluidic chip, a fluid injection system, a laser confocal observation system, and a data processing system: The fabrication process of the three-dimensional microfluidic chip includes: S1. Select representative core samples from the reservoir and use either high-resolution CT or μCT to obtain three-dimensional volume data of the pore throat spatial structure. Reconstruct the three-dimensional pore network through threshold segmentation and region growing algorithm. S2. Perform geometric smoothing and local size optimization on the three-dimensional pore network in CAD software to preserve the true pore size distribution and pore throat connectivity. At the same time, design standardized fluid inlet and outlet and observation windows at both ends of the model. S3. Using either photopolymerization or two-photon polymerization 3D printing technology, a chip preform is printed using highly transparent photosensitive resin as the material. After support removal, cleaning, secondary curing, and surface wettability adjustment, a transparent substrate is completed. S4. The printed three-dimensional porous network is plasma-bonded to a transparent substrate or encapsulated with a fluorescent adhesive that is not excited by laser, and a standard microfluidic interface is installed to achieve rapid connection with fluid injection systems, pressure sensors and imaging systems. The fluid injection system includes a micro-injection pump, connecting pipelines and a pressure sensor. It is sealed and connected to the three-dimensional microfluidic chip through the standardized microfluidic interface and is used to stably inject the displacement medium into the chip. The laser confocal observation system includes a laser confocal microscope platform, a laser source, and rapid scanning and three-dimensional reconstruction software. The three-dimensional microfluidic chip is fixed on the microscope platform. The laser emitted by the laser source enables high-resolution optical slicing. Combined with fluorescent labeling or optical contrast methods, the multiphase fluid interface is tracked, and three-dimensional image data of the displacement process is acquired in real time. The data processing system includes a time-series 3D reconstruction module and a quantitative analysis module. The time-series 3D reconstruction module continuously reconstructs the acquired 3D image data, and the quantitative analysis module calculates the remaining oil saturation, fluid connectivity, pore volume utilization rate, and seepage channel evolution based on the reconstructed data to achieve a quantitative evaluation of displacement efficiency.

2. The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 1, characterized in that: The displacement medium includes at least one of water, polymer solution, surfactant solution, and carbon dioxide.

3. The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 1, characterized in that: The adhesive encapsulation in S4 uses a three-dimensional porous structure to dock with a 1mm thick optical-grade glass substrate, and is bonded after the surface is activated by oxygen plasma; the periphery is sealed with UV adhesive, and the curing time is 5 minutes; Luer threaded microfluidic connectors are assembled at the inlet and outlet to connect to either PEEK or PTFE microtubes.

4. The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 1, characterized in that: The parameters for the quantitative evaluation of displacement efficiency also include two-dimensional classification of contact ratio, aspect ratio, shape factor, and Euler number.

5. The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 4, characterized in that: The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 1 is characterized in that: the contact ratio formula is: In the formula, A contact The actual contact area between oil and rock (μm) 2 A total The total surface area of ​​the remaining oil (μm) 2 ); The aspect ratio formula is: In the formula, L max The longest principal axis length (μm) determined by principal component analysis; L min The shortest spindle length (μm); The shape factor formula is: In the formula, S is the surface area of ​​a single oil droplet, in μm. 2 V represents the volume of a single oil droplet, in μm³. The Euler number formula is: In the formula, V is the number of vertices; E is the number of edges; F is the number of faces; and C is the number of voxels.

6. The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 1, characterized in that: The surface wettability control of S3 specifically involves: treating the chip channel surface with a silanizing agent to make the surface hydrophobic, which is used to simulate an oil-wet reservoir; or maintaining the original hydrophilic state of the surface to simulate a water-wet reservoir.

7. The three-dimensional microfluidic multiphase flow displacement visualization system based on laser confocal microscopy according to claim 1, characterized in that: The optimized three-dimensional pore network in S2 has a minimum pore size of ≥15μm, and the inlet and outlet flow channel diameters at both ends of the model are 0.5~1mm. The model is also equipped with a fixed support frame to adapt to the packaging process and the installation of the laser confocal microscope stage.

Images