Microfluidic chip

Abstract

The application discloses a microfluidic chip, which comprises a substrate, a cover plate and a hydrophobic structure; the substrate is provided with a hydrogel channel and a culture fluid channel which are in communication with each other; the cover plate is arranged on the substrate and covers the hydrogel channel and the culture fluid channel; the hydrophobic structure comprises a hydrophobic strip which is located between the hydrogel channel and the culture fluid channel, and the hydrophobic strip can prevent the hydrogel from flowing into the culture fluid channel, thereby limiting the hydrogel in the hydrogel channel; further, the junction position of the hydrophobic strip and the hydrogel channel forms a relatively stable gel interface, the gel interface provides a relatively suitable substrate hardness for cell adhesion, and the hydrogel in the hydrogel channel and the culture medium in the culture fluid channel can exchange nutrients through the hydrogel to meet the growth requirements of cells, thereby constructing a growth environment which is relatively close to the in-vivo growth environment, and the authenticity and effectiveness of the data research on the cell in-vitro culture are ensured.

Description

[0001] This application claims priority to Chinese Patent Application No. 2022109108919, filed on July 29, 2022, entitled “Microfluidic Chip”, the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of biomedical technology, and in particular to a microfluidic chip. Background Technology

[0003] Organ-on-a-chip technology is a technique for in vitro three-dimensional cell culture on a chip. By constructing microchannels, microreaction chambers, and other functional components, it allows for precise manipulation of components such as cells, fluids, gases, and the extracellular microenvironment within the chip, thereby generating biologically functional human microtissues and microorganisms. Organ-on-a-chip technology offers advantages such as integration, low consumption, high throughput, high simulation fidelity, and rapid analysis, and has broad application prospects in fields such as new drug development, disease models, personalized medicine, and aerospace medicine.

[0004] The human body transports nutrients and gases to various parts of the body via blood vessels, and exchanges nutrients, gases, and metabolites at the organ-blood vessel interface. To simulate this structure in the human body, many organ-on-a-chip technologies use porous membranes to construct such interfaces. Vascular endothelial cells and cells corresponding to organs are cultured on both sides of the porous membrane to simulate the cell arrangement and interface function of the organ-blood vessel interface.

[0005] Adding porous membranes places high demands on the properties and biocompatibility of the membranes themselves. The presence of porous membranes can also affect the free interaction and migration of cells between channels. Furthermore, the way porous membranes are integrated into the chip is relatively complex. Summary of the Invention

[0006] This application provides a microfluidic chip that enhances the fluid confinement effect in the microfluidic chip, thereby improving the yield of microfluidic chip construction.

[0007] This application provides a microfluidic chip, comprising:

[0008] The substrate has interconnected hydrogel channels and culture fluid channels;

[0009] A cover plate is disposed on the substrate and covers the hydrogel channel and the culture fluid channel;

[0010] A hydrophobic structure is provided, wherein the connection between the hydrogel channel and the culture fluid channel is divided by the hydrophobic structure, and the hydrophobic structure includes a hydrophobic strip located between the hydrogel channel and the culture fluid channel;

[0011] Wherein, after the hydrogel is injected into the hydrogel channel, the hydrophobic strip can prevent the hydrogel from flowing into the culture fluid channel.

[0012] In some embodiments, the hydrophobic strip is connected to the channel wall of the hydrogel channel; and / or, the hydrophobic strip is connected to the channel wall of the culture fluid channel.

[0013] In some embodiments, when the hydrophobic strip is connected to the channel wall of the hydrogel channel, the hydrophobic strip is connected to the surface of the channel wall of the hydrogel channel; or, the channel wall has an installation groove, and the hydrophobic strip is embedded in the installation groove.

[0014] In some embodiments, a portion of the hydrophobic strip is located within the mounting groove and a portion extends beyond the mounting groove; or, the hydrophobic strip is mounted within the mounting groove and its top is flush with the channel wall of the hydrogel channel; or, the entire hydrophobic strip is located within the mounting groove and is recessed relative to the opening of the mounting groove.

[0015] In some embodiments, the hydrogel channel extends in the longitudinal direction of the hydrogel, and the hydrophobic strip extends along the longitudinal direction.

[0016] In some embodiments, the number of hydrogel channels is one, the number of culture fluid channels is two, the hydrogel channel is located between the two culture fluid channels, and a hydrophobic strip is provided between each culture fluid channel and the hydrogel channel.

[0017] In some embodiments, the hydrogel channel includes a mass exchange section and a hydrogel inlet section and a hydrogel outlet section respectively connected to both ends of the mass exchange section, and the mass exchange section is in communication with the culture fluid channel;

[0018] The hydrophobic structure includes a first hydrophobic group disposed on the substrate and a second hydrophobic group disposed on the cover plate. The first hydrophobic group includes two first hydrophobic strips disposed at intervals. The second hydrophobic group includes two second hydrophobic strips disposed at intervals. The hydrophobic strips include the first hydrophobic strips and the second hydrophobic strips. The two first hydrophobic strips and the two second hydrophobic strips define the mass exchange section.

[0019] In some embodiments, the hydrogel inlet section, the hydrogel outlet section, and the mass exchange section are configured as a straight section, and the central axes of the hydrogel inlet section, the hydrogel outlet section, and the mass exchange section are collinear.

[0020] In some embodiments, the first hydrophobic strip and the second hydrophobic strip are arranged facing each other in the stacking direction of the cover plate and the substrate, or the first hydrophobic strip and the second hydrophobic strip are arranged offset in the stacking direction of the cover plate and the substrate.

[0021] In some embodiments, the cover plate has multiple liquid inlet channels, multiple liquid inlet connecting holes, multiple liquid outlet channels, and multiple liquid outlet connecting holes, wherein the flow cross-section of the liquid inlet connecting holes is smaller than the flow cross-section of the liquid inlet channels, and the flow cross-section of the liquid outlet connecting holes is smaller than the flow cross-section of the liquid outlet channels.

[0022] One end of each hydrogel channel is connected to an inlet channel through an inlet communication hole, and the other end of each hydrogel channel is connected to an outlet channel through an outlet communication hole.

[0023] One end of each culture fluid channel is connected to an inlet channel through an inlet communication hole, and the other end of each culture fluid channel is connected to an outlet channel through an outlet communication hole.

[0024] Based on the microfluidic chip provided in this embodiment, the connection between the hydrogel channel and the culture fluid channel is divided by a hydrophobic structure. The hydrophobic structure includes a hydrophobic strip located between the hydrogel channel and the culture fluid channel. The hydrophobic strip can prevent the hydrogel from flowing into the culture fluid channel, thereby confining the hydrogel within the hydrogel channel. Furthermore, a relatively stable gel interface is formed at the junction of the hydrophobic strip and the hydrogel channel. The gel interface provides a suitable substrate hardness for cell adhesion, and the hydrogel in the hydrogel channel and the culture medium in the culture fluid channel can exchange nutrients through the hydrogel to meet the needs of cell growth. This creates a growth environment that is closer to that in vivo, which helps to ensure the authenticity and validity of in vitro cell culture data research. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1This is a schematic diagram of the overall structure of a microfluidic chip in one embodiment of this application;

[0027] Figure 2 This is an exploded structural diagram of a microfluidic chip in one embodiment of this application;

[0028] Figure 3 This is a schematic diagram of the substrate structure in one embodiment of this application;

[0029] Figure 4 This is a cross-sectional schematic diagram of a microfluidic chip in one embodiment of this application;

[0030] Figure 5 This is a cross-sectional schematic diagram of a microfluidic chip (cells adhered to the gel interface) in one embodiment of this application;

[0031] Figure 6 This is a schematic diagram of the structure of the first and second hydrophobic strips in the microfluidic chip located in the hydrogel channel in one embodiment of this application;

[0032] Figure 7 In one embodiment of this application, based on Figure 6 A schematic diagram showing the distribution of the gel interface in the structure;

[0033] Figure 8 This is another structural schematic diagram of the substrate in one embodiment of this application;

[0034] Figure 9 This is a schematic diagram of the cover plate in one embodiment of this application;

[0035] Figure 10 This is a schematic diagram illustrating the process of using a microfluidic chip to construct a skin model in one embodiment of this application;

[0036] Figure 11 This is a schematic diagram of the process of using a microfluidic chip to construct a lung model in one embodiment of this application.

[0037] Figure label:

[0038] 10. Substrate; 11. Hydrogel channel; 111. Mass exchange section; 112. Hydrogel inlet section; 113. Hydrogel outlet section; 114. Gel interface; 116. First included angle; 117. Second included angle;

[0039] 12. Culture fluid channel; 121. Culture fluid inlet section; 122. Culture fluid outlet section; 123. Culture fluid channel section; 13. Enlarged section;

[0040] 20. Cover plate; 21. Liquid inlet channel; 22. Liquid inlet connecting hole; 23. Liquid outlet channel; 24. Liquid outlet connecting hole;

[0041] 31. First hydrophobic group; 311. First hydrophobic strip; 32. Second hydrophobic group; 321. Second hydrophobic strip;

[0042] H, crossflow direction; Z, longitudinal flow direction; D, overlapping direction. Detailed Implementation

[0043] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0044] The human body transports nutrients and gases to various parts of the body via blood vessels, and exchanges nutrients, gases, and metabolites at the organ-blood vessel interface. To simulate this structure in the human body, many organ-on-a-chip technologies use porous membranes to construct such interfaces. Vascular endothelial cells and cells corresponding to organs are cultured on both sides of the porous membrane to simulate the cell arrangement and interface function of the organ-blood vessel interface.

[0045] Adding porous membranes places high demands on the properties and biocompatibility of the membranes themselves. The presence of porous membranes can also affect the free interaction and migration of cells between channels. Furthermore, the way porous membranes are integrated into the chip is relatively complex.

[0046] To resolve the above issues, please refer to [link / reference]. Figures 1 to 3 This application provides a microfluidic chip, which includes a substrate 10, a cover plate 20, and a hydrophobic structure (not shown in the figure).

[0047] The substrate 10 has a hydrogel channel 11 and a culture fluid channel 12, which can be used to deliver at least one of the extracellular microenvironment components such as cells, fluids, gases, and drugs.

[0048] The culture fluid channel 12 can be one or two. When there is one culture fluid channel 12, the culture fluid channel 12 is located on one side of the hydrogel channel 11 and is connected to the hydrogel channel 11. The hydrogel channel 11 is filled with hydrogel, and the culture fluid channel 12 is filled with culture fluid, such as culture medium.

[0049] It should be noted that the hydrogel and culture fluid can be added by gravity without a pump, or by using an external peristaltic pump, syringe pump or other device to drive the flow of the hydrogel and culture medium, so that this flow can provide the fluid shear force environment required for cell growth.

[0050] The cover plate 20 is located on the side of the substrate 10 near the hydrogel channel 11 and the culture fluid channel 12, and covers the hydrogel channel 11 and the culture fluid channel 12, so that the hydrogel channel 11 and the culture fluid channel 12 form a channel shape with the middle closed and the two ends open, so that the hydrogel can flow in the hydrogel channel 11 and the culture medium can flow in the culture fluid channel 12.

[0051] Please see Figures 3 to 4 The connection between the hydrogel channel 11 and the culture fluid channel 12 is divided by a hydrophobic structure, which includes hydrophobic strips (such as...). Figure 4 In sections 311 and 321), the hydrogel is injected into the hydrogel channel 11. Due to the abrupt change in the capillary barrier caused by the hydrophobic strip, the hydrogel solution is confined within the hydrogel channel 11. Furthermore, a gel interface is formed at the junction of the hydrophobic strip and the hydrogel channel 11 (e.g., ...). Figure 5 The gel interface 114 provides a suitable base stiffness for cells, facilitating cell adhesion. When there is only one culture fluid channel 12, cells grow inside the hydrogel, and nutrients in the culture medium can exchange with the hydrogel through the gel interface 114 to meet the growth needs of cells located inside the hydrogel.

[0052] Please see Figure 3 When there are two culture fluid channels 12, the two culture fluid channels 12 are located on opposite sides of the hydrogel channel 11. The hydrophobic structure is located between the hydrogel channel 11 and the culture fluid channel 12. The hydrogel channel 11 is filled with hydrogel, and the culture fluid channel 12 is filled with culture medium, so as to form a three-layer structure of culture medium, hydrogel and culture medium.

[0053] Please see Figure 5 Due to the abrupt change in capillary barrier caused by the hydrophobic strip, the hydrogel is confined within the hydrogel channel 11, preventing it from flowing into the culture fluid channel 12. This confines the hydrogel within the hydrogel channel 11. Furthermore, a gel interface 114 is formed at the junction of the hydrogel and the hydrophobic strip, facilitating cell adhesion. When there are two culture fluid channels 12, cells grow in the culture medium and adhere to the gel interface 114. The gel interface 114 provides the necessary base rigidity for cell growth, ensuring uniform cell attachment and distribution. Simultaneously, the hydrogel channel 11 is located between the two culture fluid channels 12, allowing different culture media to flow through them. The culture media in the two channels 12 can exchange substances through the hydrogel within the hydrogel channel 11, meeting the nutrient requirements for cell growth in the two different culture media.

[0054] Taking the construction of a skin model as an example, hydrogel channels 11 are filled with Matrigel / collagen / fibrin hydrogels, and a gel interface 114 is formed at the junction of the hydrophobic strip and the hydrogel channel 11. One culture fluid channel 12 is filled with keratinocytes, which adhere to the gel interface 114. Then, keratinocyte culture medium is introduced into the culture fluid channel 12 to provide the nutrients required for keratinocyte growth. After culturing the keratinocytes in the culture medium for 48 hours, the culture medium in the culture fluid channel 12 is aspirated, and simultaneously, keratinocyte culture medium is introduced into the other culture fluid channel 12, allowing the keratinocyte culture medium to provide nutrients to the keratinocytes through the hydrogel.

[0055] Taking the construction of a lung model as an example, hydrogel channels 11 are filled with Matrigel / collagen / fibrin hydrogels, and a gel interface 114 is formed at the junction of the hydrophobic strip and the hydrogel channel 11. One culture fluid channel 12 is filled with lung epithelial cells, which adhere to the gel interface 114. Then, lung epithelial cell culture medium is introduced into the culture fluid channel 12 to provide the nutrients required for lung epithelial cell growth. After culturing the lung epithelial cells in the culture medium for 48 hours, the lung epithelial cell culture medium in the culture fluid channel 12 is aspirated, and simultaneously, lung epithelial cell culture medium is introduced into the other culture fluid channel 12, allowing the lung epithelial cell culture medium to provide nutrients to the lung epithelial cells through the hydrogel. Furthermore, the gel interface can simulate the real interface in a biological organism, making the cell growth environment closer to the biological growth environment, thus ensuring the authenticity and validity of the in vitro cell culture data research.

[0056] Further, please see Figures 3 to 4 The hydrophobic strip can be located on the channel wall of the hydrogel channel 11. Due to the abrupt change in the capillary barrier caused by the hydrophobic strip, the hydrogel is confined within the hydrogel channel 11 to prevent the hydrogel within the hydrogel channel 11 from flowing into the culture fluid channel 12, thereby confining the hydrogel within the hydrogel channel 11. At the same time, the junction between the hydrophobic strip and the hydrogel channel 11 forms a gel interface 114, which facilitates the uniform attachment and distribution of cells on the gel interface 114, and can provide the base rigidity and growth microenvironment required for cell growth.

[0057] In some embodiments, hydrophobic strips may also be located on the channel wall of the culture fluid channel 12, so that the hydrogel is confined within the hydrogel channel 11 due to the abrupt change in the capillary barrier caused by the hydrophobic strips.

[0058] Furthermore, when the hydrophobic strip is connected to the channel wall of the hydrogel channel 11, the hydrophobic strip can be modified with hydrophobic material strips on the channel wall of the hydrogel channel 11 by methods such as photolithography, vapor deposition, imprinting, printing, drop coating, and immersion, and the contact angle of the hydrophobic strip is controlled to be 90-100°.

[0059] For example, silica strips are attached to the channel walls of the hydrogel channel 11, and the surface wettability of the silica is altered by modifying the silica surface. Specifically, the silica surface has a large number of hydroxyl bonds, making it hydrophilic. By covalently modifying the hydroxyl groups on the surface with hydrophobic groups, the wettability of the silica surface can be changed. As the number of hydrophobic groups on the silica surface increases and the number of hydroxyl bonds decreases, the hydrophobicity gradually increases.

[0060] Please see Figures 5 to 7 Taking two culture fluid channels 12 as an example, when the hydrogel flows through the hydrophilic hydrogel channel 11, the hydrogel is confined within the hydrogel channel 11 due to the abrupt change in the capillary barrier caused by the hydrophobic strip on both sides of the hydrogel channel 11. Furthermore, a gel interface 114 is formed at the junction of the hydrophobic strip and the hydrogel channel 11, and cells can adhere to the gel interface 114 and be evenly distributed on the gel interface 114 to facilitate cell growth.

[0061] In some embodiments, the hydrogel channel 11 may have an installation groove on the channel wall near the culture fluid channel 12, and a hydrophobic strip may be embedded in the installation groove. The installation groove is used to limit the position of the hydrophobic strip. The hydrophobic strip may be modified on the bottom of the installation groove by methods such as photolithography, vapor deposition, imprinting, printing, drop coating, and soaking.

[0062] Furthermore, when the hydrophobic strip is connected to the mounting groove, the side of the hydrophobic strip away from the bottom of the mounting groove can be located inside the mounting groove, which is equivalent to the entire hydrophobic strip being located inside the mounting groove and recessed relative to the groove opening; or the hydrophobic strip is installed inside the mounting groove and its top is flush with the channel wall of the hydrogel channel 11; or the side of the hydrophobic strip away from the bottom of the mounting groove can also extend out of the mounting groove, which is equivalent to protruding from the channel wall of the hydrogel channel 11.

[0063] like Figure 1 As shown, the extension direction of the hydrogel channel 11 is the longitudinal flow direction Z of the hydrogel, and the flow direction of the hydrogel in the hydrogel channel 11 to the culture fluid channel 12 is the transverse flow direction H of the hydrogel. The hydrophobic strip extends along the longitudinal flow direction Z; the hydrophobic strip can restrict the hydrogel from flowing into the culture fluid channel 12 along the transverse flow direction H.

[0064] In some embodiments, when the height of the hydrogel channel 11 is greater than or equal to 0 μm and less than or equal to 500 μm, and the width of the hydrophobic strip is greater than or equal to 100 μm and less than or equal to 400 μm, the hydrophobic strip has a good blocking effect on the hydrogel located in the hydrogel channel 11.

[0065] Further, please see Figure 3 The hydrogel channel 11 includes a mass exchange section 111 and a hydrogel inlet section 112 and a hydrogel outlet section 113 connected to both ends of the mass exchange section 111, respectively. The mass exchange section 111 is connected to the culture fluid channel 12.

[0066] The material exchange section 111 can be configured as a straight channel, and the hydrogel inlet section 112 and the hydrogel outlet section 113 can also be configured as straight channels and connected to the material exchange section 111 to form a hydrogel channel 11 from the hydrogel inlet section 112 to the material exchange section 111 to the hydrogel outlet section 113. This facilitates the addition of hydrogel from the hydrogel inlet section 112 to the material exchange section 111, and a gel interface 114 is formed at the junction of the hydrophobic strip and the material exchange section 111 to allow cells in the culture fluid channel 12 to adhere and grow.

[0067] Meanwhile, the hydrogel inlet section 112 and the hydrogel outlet section 113 can both be straight sections, and the mass exchange section 111 can also be a straight section. Furthermore, the central axes of the hydrogel inlet section 112, the hydrogel outlet section 113, and the mass exchange section 111 are collinear, so that the hydrogel inlet section 112 and the hydrogel outlet section 113 can be set in a more suitable position to facilitate the addition of hydrogel and the collection of excess hydrogel.

[0068] In some embodiments, the central axes of the hydrogel inlet section 112 and the hydrogel outlet section 113 may form an angle with the central axis of the mass exchange section 111. In some embodiments, the angle between the central axes of the hydrogel inlet section 112 and the hydrogel outlet section 113 and the central axis of the mass exchange section 111 may be set according to the actual shape and size of the substrate 10 and the cover plate 20, and this application does not impose any limitations. It should be noted that the hydrogel inlet section 112, the hydrogel outlet section 113, and the mass exchange section 111 may extend in a straight line to reduce the flow resistance of the hydrogel in the hydrogel channel 11, so as to facilitate the flow of the hydrogel.

[0069] In some embodiments, the hydrogel inlet section 112, the hydrogel outlet section 113, and the material exchange section 111 may also be of other shapes, which can be set according to actual needs, and this application does not impose any restrictions.

[0070] The hydrophobic structure includes a first hydrophobic group 31 disposed on the substrate 10 and a second hydrophobic group 32 disposed on the cover plate 20. The first hydrophobic group 31 includes two first hydrophobic strips 311, and the second hydrophobic group 32 includes two second hydrophobic strips 321. The hydrophobic strips include the first hydrophobic strips 311 and the second hydrophobic strips 321. The two first hydrophobic strips 311 and the two second hydrophobic strips 321 define a mass exchange section 111.

[0071] The mass exchange section 111 includes a first mass exchange section (not shown in the figure) and a second mass exchange section (not shown in the figure). The first mass exchange section is close to the substrate 10, and the second mass exchange section is close to the cover plate 20. Two spaced-apart first hydrophobic strips 311 on the substrate 10 define the first mass exchange section. The first hydrophobic strips 311 have a confining effect on the hydrogel, thereby confining the hydrogel in the first mass exchange section. Two spaced-apart second hydrophobic strips 321 on the cover plate 20 define the second mass exchange section. The second hydrophobic strips 321 have a confining effect on the hydrogel, thereby confining the hydrogel in the second mass exchange section. The combined action of the two first hydrophobic strips 311 and the two second hydrophobic strips 321 confines the hydrogel within the hydrogel channel 11, preventing the hydrogel from entering the culture fluid channel 12.

[0072] Furthermore, due to the combined restriction of the first hydrophobic strip 311 and the second hydrophobic strip 321, a relatively stable gel interface 114 is formed at the junction of the hydrophobic strip and the hydrogel channel 11, which helps the culture medium in the culture fluid channel 12 and the nutrients in the hydrogel to exchange substances. At the same time, the relatively stable gel interface 114 facilitates cell adhesion, making it closer to the growth environment of organisms, which helps to ensure the authenticity and validity of cell culture data research.

[0073] The culture fluid channel 12 may also include a culture fluid channel segment 123 and a culture fluid inlet segment 121 and a culture fluid outlet segment 122 located at both ends of the culture fluid channel segment 123, so as to form a culture fluid channel 12 from the culture fluid inlet segment 121 to the culture fluid channel segment 123 to the culture fluid outlet segment 122, so as to facilitate the addition of culture medium from the culture fluid inlet segment 121 into the culture fluid channel segment 123 to provide nutrients for cell growth.

[0074] Please see Figure 8 Combination Figure 3The culture fluid channel 12 is located on one side of the hydrogel channel 11. The culture fluid inlet section 121 and the culture fluid outlet section 122 can be configured as straight sections. The culture fluid inlet section 121 and the culture fluid channel section 123 are configured at a first included angle 116, and the culture fluid outlet section 122 and the culture fluid channel section 123 are configured at a second included angle 117, so that the liquid addition port and liquid outlet of the culture medium are set at appropriate positions on the substrate 10 and the cover plate 20, so as to facilitate the operator to add and collect the culture medium. In this application, the size of the first included angle 116 and the second included angle 117 is not limited and can be set according to actual needs.

[0075] The culture fluid channel 12 and the hydrogel channel 11 can be positioned in a U-shape. The culture fluid channel segment 123 can be positioned closer to the hydrogel channel 11 so that the liquid inlet of the culture fluid inlet segment 121 and the liquid outlet of the culture fluid outlet segment 122 are far away from the hydrogel channel 11. At the same time, the culture fluid channel segment 123 is close to the hydrogel channel 11 so that the liquid inlet of the culture fluid inlet segment 121 and the liquid outlet of the culture fluid outlet segment 122 are positioned in a suitable location to facilitate the addition of culture medium and the collection of excess culture medium.

[0076] Further, please see Figures 4 to 7 Combination Figure 2 The first hydrophobic strip 311 and the second hydrophobic strip 321 are arranged opposite each other in the stacking direction D of the cover plate 20 and the substrate 10. The contact angle of the hydrophobic strip is 90° so that a straight gel interface 114 is formed at the junction of the hydrophobic strip and the hydrogel channel 11.

[0077] Figure 5 The diagram illustrates the state of cells adhering to the gel interface 114. Cells can adhere to the gel interface 114 and are evenly distributed on the gel interface 114 to facilitate cell growth.

[0078] Figure 6 The diagram shows that, under the interaction of the hydrogel in the hydrogel channel 11 and the culture medium in the culture fluid channel 12, the first hydrophobic strip 311 and the second hydrophobic strip 321 are correspondingly arranged with a contact angle of 90°.

[0079] It should be noted that the contact angle refers to the angle between the solid-liquid interface, through the liquid interior, and at the interface between the solid, liquid, and gas phases; in this application, the contact angle is the angle between the interface between the first hydrophobic strip 311 and the hydrogel, through the hydrogel interior, and the interface between the air and the hydrogel in the culture fluid channel 12.

[0080] according to Figure 6 The settings in can be obtained Figure 7The simulation results show that the white part represents the contact interface (gel interface 114) between the hydrogel and the air in the culture fluid channel 12. It can be seen that the hydrogel is confined in the hydrogel channel 11, and the gel interface 114 is close to a straight line. This gel interface 114 helps the cells to be evenly distributed on the interface during the process of cell suspension attaching and growing on the gel wall.

[0081] In some embodiments, the first hydrophobic strip 311 and the second hydrophobic strip 321 may be misaligned in the stacking direction D of the cover plate 20 and the substrate 10 so that a gel interface 114 is formed between the hydrogel and the air. The first hydrophobic strip 311 and the second hydrophobic strip 321 have a restrictive effect on the flow of the hydrogel, thereby preventing the hydrogel in the hydrogel channel 11 from flowing into the culture fluid channel 12.

[0082] Further, please see Figure 9 The cover plate 20 has multiple liquid inlet channels 21, multiple liquid inlet connecting holes 22, multiple liquid outlet channels 23, and multiple liquid outlet connecting holes 24. The flow cross-section of the liquid inlet connecting hole 22 is smaller than that of the liquid inlet channel 21, and the flow cross-section of the liquid outlet connecting hole 24 is smaller than that of the liquid outlet channel 23.

[0083] One end of each hydrogel channel 11 is connected to an inlet channel 21 through an inlet communication hole 22, and the other end of each hydrogel channel 11 is connected to an outlet channel 23 through an outlet communication hole 24.

[0084] Please combine Figures 1 to 3 The hydrogel channel 11 includes a hydrogel inlet section 112, a hydrogel outlet section 113, and a mass exchange section 111. The liquid inlet channel 21 corresponds to the liquid inlet of the hydrogel inlet section 112, and a liquid inlet connecting hole 22 is provided on the side of the liquid inlet channel 21 near the liquid inlet of the hydrogel inlet section 112. The flow cross section of the liquid inlet connecting hole 22 is smaller than that of the liquid inlet channel 21, so that the hydrogel in the liquid inlet channel 21 can be added to the mass exchange section 111 through the liquid inlet connecting hole 22. At the same time, the larger cross section of the liquid inlet channel 21 allows the liquid outlet end of the pipette to enter, which helps the hydrogel in the pipette to enter the hydrogel inlet section 112 through the liquid inlet connecting hole 22. Furthermore, placing the liquid outlet end of the pipette in the liquid inlet channel 21 can also prevent the hydrogel in the pipette from being contaminated. Meanwhile, an enlarged portion 13 is provided at the position of the hydrogel inlet section 112 near the liquid inlet communication hole 22 so that all the hydrogel in the liquid inlet communication hole 22 can enter the hydrogel inlet section 112.

[0085] The liquid outlet channel 23 corresponds to the liquid outlet of the hydrogel outlet section 113, and a liquid outlet connecting hole 24 is provided on the side of the liquid outlet channel 23 near the liquid outlet of the hydrogel outlet section 113. The flow cross section of the liquid outlet connecting hole 24 is smaller than that of the liquid outlet channel 23. The smaller cross section of the liquid outlet connecting hole 24 facilitates the connection between the liquid outlet channel 23 and the hydrogel outlet section 113, thereby allowing excess hydrogel in the hydrogel outlet section 113 to be discharged into the liquid outlet channel 23. At the same time, the larger cross section of the liquid outlet channel 23 can store more hydrogel, and the operator can remove it when the amount of hydrogel in the liquid outlet channel 23 reaches a certain amount, thereby improving the removal efficiency of excess hydrogel.

[0086] Meanwhile, an enlarged section 13 is provided at the position of the hydrogel outlet section 113 near the liquid outlet communication hole 24, so as to gather the excess hydrogel to the enlarged section 13, and then let the excess hydrogel enter the liquid outlet channel 23 through the liquid outlet communication hole 24 via the enlarged section 13.

[0087] One end of each culture fluid channel 12 is connected to an inlet channel 21 through an inlet communication hole 22, and the other end of each culture fluid channel 12 is connected to an outlet channel 23 through an outlet communication hole 24.

[0088] The culture fluid channel 12 includes a culture fluid channel section 123 and a culture fluid inlet section 121 and a culture fluid outlet section 122 located at both ends of the culture fluid channel section 123. The inlet channel 21 corresponds to the inlet of the culture fluid inlet section 121, and an inlet connecting hole 22 is provided on the side of the inlet channel 21 near the inlet of the culture fluid inlet section 121. The flow cross section of the inlet connecting hole 22 is smaller than that of the inlet channel 21, so that the culture medium in the inlet channel 21 can be added to the culture fluid channel 12 through the inlet connecting hole 22. At the same time, the larger cross section of the inlet channel 21 allows the outlet end of the pipette to enter, which helps the culture medium in the pipette to enter the culture fluid channel 12 through the inlet connecting hole 22. Furthermore, placing the outlet end of the pipette in the inlet channel 21 can also prevent the culture medium in the pipette from being contaminated.

[0089] Meanwhile, an expansion section 13 is provided in the culture fluid inlet section 121 near the liquid inlet communication hole 22 so that the culture medium in the liquid inlet communication hole 22 can all enter the culture fluid inlet section 121.

[0090] The liquid outlet channel 23 corresponds to the liquid outlet of the culture fluid outlet section 122, and a liquid outlet connecting hole 24 is provided on the side of the liquid outlet channel 23 near the liquid outlet of the culture fluid outlet section 122. The flow cross section of the liquid outlet connecting hole 24 is smaller than that of the liquid outlet channel 23. The smaller cross section of the liquid outlet connecting hole 24 facilitates the connection between the liquid outlet channel 23 and the culture fluid outlet section 122, thereby allowing excess culture medium in the culture fluid outlet section 122 to be discharged into the liquid outlet channel 23. At the same time, the larger cross section of the liquid outlet channel 23 can store more excess culture medium, which can be removed by the operator when the amount of excess culture medium in the liquid outlet channel 23 reaches a certain amount, thereby improving the removal efficiency of excess culture medium.

[0091] Meanwhile, an enlarged section 13 is provided at the position of the culture fluid outlet section 122 near the liquid outlet communication hole 24, so as to gather the excess culture medium into the enlarged section 13, and then through the enlarged section 13, the excess culture medium enters the culture fluid inlet section of the liquid outlet channel 23 through the liquid outlet communication hole 24.

[0092] Please see Figure 10 The method of using the microfluidic chip in this embodiment to construct a skin model includes:

[0093] S11. Assemble the cover plate 20 and the substrate 10 to form a microfluidic chip.

[0094] S12. Sterilize the microfluidic chip.

[0095] S13. Add Matrigel / collagen / fibrin mixed hydrogel into the hydrogel channel 11. The hydrophobic strip can restrict the Matrigel / collagen / fibrin mixed hydrogel within the hydrogel channel 11. Excess Matrigel / collagen / fibrin mixed hydrogel flows out from the outlet channel 23 through the outlet communication hole 24.

[0096] S14. After the Matrigel / collagen / fibrin mixed hydrogel solidifies, a gel interface 114 of the Matrigel / collagen / fibrin mixed hydrogel is formed.

[0097] S15. Skin keratinocytes are added from the inlet channel 21 to one of the culture fluid channels 12, so that the added skin keratinocytes adhere to the gel interface 114. Skin keratinocyte culture medium is added from the inlet channel 21 and enters the culture fluid channel 12 through the inlet communication hole 22. Excess skin keratinocyte culture medium flows out from the outlet channel 23 through the outlet communication hole 24.

[0098] S16. After culturing skin keratinocytes in skin keratinocyte culture medium for 48 hours, the skin keratinocyte culture medium in the culture fluid channel 12 is aspirated dry from the outlet channel 23; skin keratinocyte culture medium is added to another culture fluid channel 12 from the inlet channel 21. The skin keratinocyte culture medium can provide nutrition to the skin keratinocytes through Matrigel / collagen / fibrin mixed hydrogel.

[0099] S17. After successful cell culture, a skin epidermal model is constructed for subsequent testing.

[0100] Please see Figure 11 The method of using the microfluidic chip in this embodiment for constructing a lung model includes:

[0101] S21. Assemble the cover plate 20 and the substrate 10 to form a microfluidic chip.

[0102] S22. Sterilize the microfluidic chip.

[0103] S23. Add Matrigel / collagen / fibrin mixed hydrogel into the hydrogel channel 11. The hydrophobic strip can restrict the Matrigel / collagen / fibrin mixed hydrogel within the hydrogel channel 11. Excess Matrigel / collagen / fibrin mixed hydrogel flows out from the outlet channel 23 through the outlet communication hole 24.

[0104] S24. After the Matrigel / collagen / fibrin mixed hydrogel solidifies, a gel interface 114 of the Matrigel / collagen / fibrin mixed hydrogel is formed.

[0105] S25. Lung epithelial cells are added from the inlet channel 21 to one of the culture fluid channels 12, so that the added lung epithelial cells adhere to the gel interface 114. Lung epithelial cell culture medium is added from the inlet channel 21 and enters the culture fluid channel 12 through the inlet communication hole 22. Excess lung epithelial cell culture medium flows out from the outlet channel 23 through the outlet communication hole 24.

[0106] S26. After culturing lung epithelial cells in lung epithelial cell culture medium for 48 hours, the lung epithelial cell culture medium in the culture fluid channel 12 is aspirated from the outlet channel 23; lung epithelial cell culture medium is added to another culture fluid channel 12 from the inlet channel 21. The lung epithelial cell culture medium can provide nutrition to the lung epithelial cells through Matrigel / collagen / fibrin mixed hydrogel.

[0107] S27. After successful cell culture, a skin epidermal model is constructed for subsequent testing.

[0108] In the accompanying drawings of this embodiment, the same or similar reference numerals correspond to the same or similar components. In the description of this application, it should be understood that if terms such as "upper," "lower," "left," and "right" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, they are 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. Therefore, the terms used to describe positional relationships in the accompanying drawings are only for illustrative purposes and should not be construed as limiting this patent. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0109] The above are merely preferred embodiments of this application and are not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A microfluidic chip, characterized by, The microfluidic chip comprises: a substrate, having a hydrogel channel and a culture fluid channel which are in communication with each other; a cover plate, covering the substrate and covering the hydrogel channel and the culture fluid channel; a hydrophobic structure, delimiting the communication between the hydrogel channel and the culture fluid channel, the hydrophobic structure comprising a hydrophobic strip, the hydrophobic strip being located between the hydrogel channel and the culture fluid channel, the hydrophobic strip comprising a first hydrophobic strip and a second hydrophobic strip, the first hydrophobic strip being arranged on the substrate, and the second hydrophobic strip being arranged on the cover plate; wherein, after the hydrogel is injected into the hydrogel channel, the first hydrophobic strip and the second hydrophobic strip can jointly block the hydrogel from flowing into the culture fluid channel, so that the hydrogel forms a gel interface between the first hydrophobic strip and the second hydrophobic strip; the hydrophobic strip is connected to the channel wall of the hydrogel channel; and / or, the hydrophobic strip is connected to the channel wall of the culture fluid channel.

2. The microfluidic chip according to claim 1, wherein: when the hydrophobic strip is connected to the channel wall of the hydrogel channel, the hydrophobic strip is connected to the surface of the channel wall of the hydrogel channel; or, the channel wall is provided with a mounting groove, and the hydrophobic strip is embedded in the mounting groove.

3. The microfluidic chip of claim 2, wherein, part of the hydrophobic strip is located in the mounting groove and part of the hydrophobic strip protrudes out of the mounting groove; or, the hydrophobic strip is mounted in the mounting groove and the top of the hydrophobic strip is flush with the channel wall of the hydrogel channel; or, the hydrophobic strip is located in the mounting groove as a whole and is recessed relative to the slot opening of the mounting groove.

4. The microfluidic chip of claim 1, wherein, The extension direction of the hydrogel channel itself is the longitudinal flow direction of the hydrogel, and the hydrophobic strip extends along the longitudinal flow direction.

5. The microfluidic chip of claim 1, wherein, The number of the hydrogel channel is one, the number of the culture fluid channel is two, and the hydrogel channel is located between the two culture fluid channels, and the hydrophobic strip is arranged between each culture fluid channel and the hydrogel channel.

6. The microfluidic chip according to claim 1, wherein: the hydrogel channel comprises a substance exchange section and a hydrogel inlet section and a hydrogel outlet section connected to both ends of the substance exchange section respectively, and the substance exchange section is in communication with the culture fluid channel; the hydrophobic structure comprises a first hydrophobic group arranged on the substrate and a second hydrophobic group arranged on the cover plate, the first hydrophobic group comprises two first hydrophobic strips arranged at intervals, and the second hydrophobic group comprises two second hydrophobic strips arranged at intervals, the hydrophobic strip comprises the first hydrophobic strip and the second hydrophobic strip, and two first hydrophobic strips and two second hydrophobic strips define the substance exchange section.

7. The microfluidic chip according to claim 6, wherein: the hydrogel inlet section, the hydrogel outlet section and the substance exchange section are arranged as straight sections, and the central axes of the hydrogel inlet section, the hydrogel outlet section and the substance exchange section are collinear.

8. The microfluidic chip of claim 6, wherein, The first hydrophobic strip and the second hydrophobic strip are arranged in alignment in the stacking direction of the cover plate and the substrate, or the first hydrophobic strip and the second hydrophobic strip are arranged in misalignment in the stacking direction of the cover plate and the substrate.

9. The microfluidic chip according to any one of claims 1-8, wherein, The cover plate has a plurality of liquid inlet flow channels, a plurality of liquid inlet communication holes, a plurality of liquid outlet flow channels, and a plurality of liquid outlet communication holes, the flow cross section of the liquid inlet communication holes is smaller than the flow cross section of the liquid inlet flow channels, and the flow cross section of the liquid outlet communication holes is smaller than the flow cross section of the liquid outlet flow channels; One end of each of the hydrogel channels is communicated with one of the liquid inlet flow channels through one of the liquid inlet communication holes, and the other end of each of the hydrogel channels is communicated with the liquid outlet flow channel through one of the liquid outlet communication holes; One end of each of the culture fluid channels is communicated with one of the liquid inlet flow channels through one of the liquid inlet communication holes, and the other end of each of the culture fluid channels is communicated with the liquid outlet flow channel through one of the liquid outlet communication holes.

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