Parallel multi-organ chip and preparation method thereof

Abstract

The invention provides a parallel multi-organ chip and a preparation method thereof. The parallel multi-organ chip comprises a liquid inlet main channel, a plurality of parallel branches and a liquid outlet main channel, the liquid inlet main pipeline is sequentially connected with inlets of all the parallel branches through all the branch points, and the liquid outlet main pipeline is sequentially connected with outlets of all the parallel branches through all the branch points; the micro-channel section of the liquid inlet main channel is reduced in a stepped manner at each bifurcation point except the first bifurcation point along the flow direction of the liquid, so that the flow resistance is increased; and the micro-channel section of the liquid outlet main channel is increased in a stepped manner at each bifurcation point except the last bifurcation point along the flow direction of the liquid, so that the flow resistance is reduced. According to the chip, equal-flow-velocity distribution without external control is achieved structurally, five-channel uniform perfusion can be achieved only through one liquid driving source, the number of perfusion modules is remarkably reduced, meanwhile, an extra chip area is not needed for arranging micro-channels for flow division, integration is facilitated, the system complexity and the use threshold are reduced, and the chip is suitable for large-scale popularization and application. The high-flux organ chip is convenient to popularize.

Description

Technical Field

[0001] This invention relates to organ-on-a-chip, and more specifically to a parallel multi-organ-on-a-chip and its fabrication method. Background Technology

[0002] Organ-on-a-chip (OABC) is a microfluidic device that simulates the functions of human tissues and organs, typically consisting of cell culture chambers and microchannels. The microchannels connect multiple functional modules, enabling not only the supply of culture medium and the removal of metabolic products, but also the connection of different organ chambers, thus constructing a multi-organ interconnected chip system. In microfluidic systems, fluid movement is usually in a laminar flow state with low Reynolds numbers; therefore, the rationality of the microchannel structure is crucial to the accuracy of simulating physiological processes. [1] .

[0003] In applications such as drug screening and disease modeling, repeated experiments and parallel control experiments are necessary to ensure the generalizability of experimental conclusions. Therefore, multiple replicated organoid culture experiments are often designed. Existing designs include studies that use multiple independent perfusion units to drive each group of organ connectivity structures for replicated experiments. For example, the organ-on-a-chip system designed by TissUse... [2-3] The design incorporates two independent organ interconnect modules, each with its own inlet and outlet fluid ports, enabling independent fluid perfusion. However, this structure requires an additional fluid infusion control system for each additional culture module, resulting in low chip throughput. Furthermore, the complexity of the external perfusion modules limits system integration and the realization of high-throughput experiments. Robbert J. Rottier's team at Erasmus Medical Center in the Netherlands has developed another design called Simple-Flow. [4] This refers to a 3D-printed porous flow plate used for co-culturing primary human lung cells at the gas-liquid interface. It enables parallel experiments connecting four groups of organs by setting up multiple unconnected channels. However, each group still needs to be independently connected to an external perfusion device, which presents similar problems.

[0004] Parallel organ-on-a-chip (NOASC) designs can reduce the use of external perfusion devices in repetitive experiments. In NOASC, fluid is sequentially distributed to multiple branch channels from the same inlet, thus simplifying parallel control and repetitive experiments. However, NOASC also faces the problem of flow shunting. If the flow rates in each branch are inconsistent after shunting, it will directly affect the consistency of experimental conditions and the reproducibility of experimental results. Therefore, achieving consistent flow rates across multiple parallel channels is one of the key challenges in NOASC design.

[0005] One current high-throughput parallel organ-on-a-chip is... Figure 3 As shown, multiple parallel organ connection regions are integrated in the chip and connected through a T-shaped or Y-shaped bifurcation network. [5]To achieve flow distribution, the three-way nodes are designed in a T- or Y-shape. Theoretically, this structure can achieve consistent flow rate distribution without requiring multiple perfusion modules. However, since microfluidic distribution typically relies on a tree-like microchannel structure with T- or Y-shaped branching, this type of structure not only limits the number of channels to a power of 2 distribution (2, 4, 8, etc.), but also occupies a large chip area, making it unsuitable for flexibly deploying any number of culture units on organ-on-a-chip. Furthermore, its flow distribution network occupies a large area on the chip, making it difficult to integrate into space-constrained chip designs.

[0006] References:

[0007] 1. Filippi M, Buchner T, Yasa O, Weirich S, Katzschmann RK. Microfluidic Tissue Engineering and Bio-Actuation. Adv Mater. 2022;34(23):e2108427. doi:10.1002 / adma.202108427.

[0008] 2. Schimek, K.; Busek, M.; Brincker, S.; Groth, B.; Hoffmann, S.;Lauster, R.; Lindner, G.; Lorenz, A.; Menzel, U.; Sonntag, F.; et al. Integrating biological vasculature into a multi-organ-chip microsystem. Labon a chip 2013, 13 (18), 3588-3598. DOI: 10.1039 / c3lc50217a.

[0009] 3. Maschmeyer, I.; Lorenz, AK; Schimek, K.; Hasenberg, T.; Ramme, AP; Hubner, J.; Lindner, M.; Drewell, C.; Bauer, S.; Thomas, A.; et al. 2688-2699.DOI: 10.1039 / c5lc00392j.

[0010] 4. Iriondo C, Koornneef S, Skarp KP, Buscop-van Kempen M, Boerema-deMunck A, Rottier RJ. Simple-Flow: A 3D-Printed Multiwell Flow Plate toCoculture Primary Human Lung Cells at the Air-Liquid Interface. ACS BiomaterSci Eng. 2025;11(1):451-462. doi:10.1021 / acsbiomaterials.4c01322.

[0011] 5. Kong J, Luo Y, Jin D, et al. A novel microfluidic model can mimic organ-specific metastasis of circulating tumor cells. Oncotarget. 2016;7(48):78421-78432. doi:10.18632 / oncotarget.9382. Summary of the Invention

[0012] The purpose of this invention is to provide a parallel multi-organ chip and its fabrication method, so as to achieve isotropic flow distribution without external control in structure.

[0013] To achieve the above objectives, the present invention provides a parallel multi-organ chip, comprising microchannels such as an inlet main channel, multiple parallel branches, and an outlet main channel connected in sequence; the inlet main channel connects to the inlets of each parallel branch channel in sequence through various bifurcation points, and the outlet main channel connects to the outlets of each parallel branch channel in sequence through various bifurcation points; the cross-section of the microchannel in the inlet main channel decreases stepwise along the liquid flow direction at each bifurcation point except for the first bifurcation point, thereby increasing the flow resistance; the cross-section of the microchannel in the outlet main channel increases stepwise along the liquid flow direction at each bifurcation point except for the last bifurcation point, thereby decreasing the flow resistance.

[0014] The inlet and outlet channels each include a branch start point interface segment and a branch end point interface segment that are sequentially connected to each branch through multiple bifurcation points. Both the branch start point interface segment and the branch end point interface segment are straight lines.

[0015] The starting and ending interface segments of each branch are perpendicular to all branches, and the liquid flow direction within the starting and ending interface segments is the same; all parameters of each branch are consistent.

[0016] Determine the geometric parameters of the microchannels in the inlet and outlet channels, including determining the flow resistance of each section based on the uniform flow rate of each branch, and then deriving the geometric parameters of the microchannels in reverse.

[0017] The flow resistance of each segment is determined based on the uniform flow rate of each branch, including: equating the flow resistance of each microchannel to resistance to establish an analog circuit model; in the analog circuit model, setting the equal current of each branch as the optimization objective to calculate the resistance of each segment and each branch of the inlet and outlet main channels separated by each bifurcation point, and then equating it to the flow resistance of each segment.

[0018] The main inlet channel is provided with an inlet and a sample inlet connected to it, and the main outlet channel is provided with an outlet and a sample inlet connected to it; the branch channel is provided with a receiving hole for inserting into the culture chamber, and the bottom of the receiving hole is connected to the microchannel.

[0019] The parallel multi-organ chip includes an integral main body and a pressure-sensitive membrane sealed to the bottom of the main body.

[0020] On the other hand, the present invention provides a method for fabricating a parallel multi-organ chip, characterized in that it includes:

[0021] S1: Initially construct the structural model of the parallel multi-organ chip, and determine the arrangement of microchannels such as the inlet main channel, multiple parallel branches, and the outlet main channel; wherein, the parallel multi-organ chip includes microchannels such as the inlet main channel, multiple parallel branches, and the outlet main channel connected in sequence; the inlet main channel connects to the inlet of each parallel branch in sequence through each bifurcation point, and the outlet main channel connects to the outlet of each parallel branch in sequence through each bifurcation point.

[0022] S2: Equivalent the current resistance of each microchannel to a resistor in order to establish an analog circuit model;

[0023] S3: In the analog circuit model, the current of each branch is set as the optimization goal, so as to optimize the resistance of each segment and branch of the inlet and outlet main channels separated by each bifurcation point, which is then equivalent to the flow resistance of each segment.

[0024] S4: Using the Hagen-Poiseuille formula, the geometric parameters of the microchannel are derived by back-calculating the flow resistance of each segment; based on the geometric parameters of the microchannel, the geometric parameters of the microchannel in the parallel multi-organ chip structural model are adjusted so that the cross-section of the microchannel in the inlet channel decreases stepwise at each bifurcation point along the liquid flow direction except for the first bifurcation point, thereby increasing the flow resistance; the cross-section of the microchannel in the outlet channel increases stepwise at each bifurcation point along the liquid flow direction except for the last bifurcation point, thereby decreasing the flow resistance.

[0025] S6: Based on the structural model of the parallel multi-organ chip, fabricate the corresponding parallel multi-organ chip.

[0026] The geometric parameters of the microchannel include the width and height of the microchannel; the constraints on the geometric parameters of the microchannel include: the channel width of the microchannel cannot overlap with other microchannels; the height of the microchannel cannot exceed the total height of the chip.

[0027] Step S6 specifically includes:

[0028] PMMA material is used as the main body of the parallel multi-organ chip. The microchannels located at the bottom of the chip and the accommodating holes for inserting the culture chamber, as well as the liquid inlet, sample outlet, liquid outlet and sampling port are located above the microchannels through integrated machine tool processing. After the main body is processed, the bottom of the main body is sealed with a pressure-sensitive membrane.

[0029] After step S4 and before step S6, the method further includes: using simulation software to perform fluid simulation verification on the structural model of the parallel multi-organ chip, and fine-tuning the structure based on the simulation results to obtain a structural model of the parallel multi-organ chip that satisfies uniform flow distribution.

[0030] The parallel multi-organ-on-a-chip of the present invention achieves uniform flow rate distribution without external control in its structure. It can achieve uniform perfusion in five channels with only one liquid driving source, which significantly reduces the number of perfusion modules, lowers the system complexity and the threshold for use, and facilitates the promotion of high-throughput organ-on-a-chip platforms.

[0031] The parallel multi-organ chip of this invention achieves uniform current distribution by controlling the channel geometry dimensions. The structure is simple and highly controllable, with low manufacturing costs. Precise flow resistance matching can be achieved directly through dimensional design, avoiding complex external control systems. Furthermore, uniform current distribution is achieved only by changing local dimensions, resulting in a simple structure that eliminates the need for additional chip area to set up microchannels (T-type and Y-type) for current distribution, facilitating integration and saving chip area.

[0032] The parallel multi-organ chip of the present invention can be expanded to a shunt chip with any number of branches, and has good versatility and scalability. It is particularly suitable for the design of highly integrated microfluidic chips under space-constrained conditions, and can also be widely used in other biochip systems that require fluid flow consistency control. Attached Figure Description

[0033] Figure 1 This is a bottom-view schematic diagram of a parallel multi-organ chip according to an embodiment of the present invention.

[0034] Figure 2 Is it like this? Figure 1 The diagram shows a three-dimensional structure of a parallel multi-organ chip, where the local width of the parallel multi-organ chip is varied.

[0035] Figure 3 This is a preliminary structural model of a parallel multi-organ chip and a structural diagram of an analog circuit model. It was found that the current in the two side branches is greater than that in the middle branch.

[0036] Figure 4 It is a structural diagram of the optimized analog circuit model and the corresponding parallel multi-organ chip structural model.

[0037] Figure 5 It is a three-dimensional structural diagram of a parallel multi-organ chip with varying local height.

[0038] Figure 6 yes Figure 2 The simulation results are shown in the figure.

[0039] Figure 7 yes Figure 5 The simulation results are shown in the figure. Detailed Implementation

[0040] The parallel multi-organ chip of this invention optimizes the size of microchannels primarily based on the following principles:

[0041] This invention uses the microfluidic-circuit analogy to guide the structural design of microchannels, where fluid transport in microfluidics and current transport in circuits have similar laws.

[0042] For example, the fluid resistance parameter given by Hagen-Poiseuille's law is similar to the resistance given by Ohm's law in electronic circuits, as detailed in the references [Bruus, Henrik. Theoretical microfluidics. Vol. 18. Oxforduniversity press, 2007. 1. Filippi M, Buchner T, Yasa O, Weirich S, Katzschmann RK. Microfluidic Tissue Engineering and Bio-Actuation. Adv Mater.2022;34(23):e2108427. doi:10.1002 / adma.202108427] and [Rousset N, Lohasz C, BoosJA, Misun PM, Cardes F, Hierlemann A. Circuit-Based Design of MicrofluidicDrop Networks. Micromachines (Basel). 2022;13(7):1124. Published 2022 Jul [16.doi:10.3390 / mi13071124]. For a fluid loop consisting of a pressure source P and a fluid resistance R, according to the Hagen-Poiseuille law, the volumetric flow rate Q of the fluid in the microchannel is:

[0043] ,

[0044] The equations show that periodic flow rates can be obtained by changing the pressure difference ΔP across the microchannel, the fluid resistance R, or both. The fluid resistance R is a function of the microchannel geometry, dimensions, and fluid properties. The fluid resistance of a microchannel with a circular cross-section... Fluid resistance of microchannels with rectangular cross-sections They are represented as follows:

[0045] ,

[0046] ,

[0047] Where, r i is the radius of the microchannel, w is the width of the microchannel, h is the height of the microchannel, μ is the dynamic viscosity of the liquid, and l is the length of the microchannel.

[0048] Based on this invention, the flow resistance of local microchannels within the chip can be obtained, and the entire flow channel can be likened to a circuit diagram. According to this idea, the method of changing the resistance value in the circuit branch and thus changing the current of the branch can be simulated. By optimizing the local dimensions at the microchannel bifurcation point, the local flow resistance in the main channel can be actively adjusted to control the pressure difference of each branch, thereby achieving equal flow rate distribution without external control in the structure, realizing organ-on-a-chip with high throughput and low peripheral load.

[0049] like Figure 1 and Figure 2 As shown, the parallel multi-organ-on-a-chip of the present invention includes microchannels such as an inlet main channel 10, multiple parallel branches 20, and an outlet main channel 30 connected in sequence. An inlet port 11 and a sample inlet 12 are connected above the inlet main channel 10, and an outlet port 31 and a sampling port 32 are connected above the outlet main channel 30. The inlet port 11 and the outlet port 31 are used to connect to a perfusion device to realize fluid circulation; the inlet port is the starting point of the fluid flow channel within the organ-on-a-chip. The perfusion device is preferably a micropump. The sample inlet port 12 and the sampling port 32 facilitate sampling operations.

[0050] In this embodiment, the inlet 11, the sample inlet 12, the outlet 31, and the sampling port 32 are all located on the same side of the parallel multi-organ chip to facilitate connection to the perfusion device.

[0051] The inlet main channel 10 connects sequentially to the inlets of each parallel branch channel 20 through various branch points, and the outlet main channel 30 connects sequentially to the outlets of each parallel branch channel 20 through various branch points. Thus, liquid enters each branch channel 20 through the inlet main channel, passes through multiple branch points, and then enters the outlet main channel 30 through multiple branch points at the outlet of each branch channel 20, and is then connected to the outlet.

[0052] In this embodiment, the inlet main channel 10 and the outlet main channel 30 each include a branch starting interface section 13 and a branch ending interface section 33 that are sequentially connected to each branch 20 through multiple bifurcation points. Both the branch starting interface section 13 and the branch ending interface section 33 are straight lines. Both the branch starting interface section 13 and the branch ending interface section 33 are perpendicular to all branches 20, and the liquid flow direction within the branch starting interface section 13 and the branch ending interface section 33 is the same.

[0053] The cross-sectional area of ​​the microchannel in the inlet channel 10 decreases stepwise at each bifurcation point along the liquid flow direction, except for the first bifurcation point, thus increasing flow resistance. The cross-sectional area of ​​the microchannel in the outlet channel 30 increases stepwise at each bifurcation point along the liquid flow direction, except for the last bifurcation point, thus decreasing flow resistance. Changing the microchannel cross-section includes changing the height and / or width of the microchannel cross-section.

[0054] Determining the geometric parameters of the microchannels in the inlet main channel 10 and the outlet main channel 30 includes determining the flow resistance of each segment based on the uniform flow rate of each branch, and then deriving the geometric parameters of the microchannels. In this embodiment, determining the flow resistance of each segment based on the uniform flow rate of each branch includes: equating the flow resistance of each microchannel to resistance to establish an analog circuit model; in the analog circuit model, setting the equal current of each branch 20 (i.e., uniform flow rate) as the optimization objective to calculate the resistance of each segment of the inlet main channel 10 and the outlet main channel 30 separated by each bifurcation point and the resistance of each branch 20, and then equating them to the flow resistance of each segment.

[0055] Therefore, the parallel multi-organ chip of the present invention, by locally controlling the microchannel structure at the bifurcation point where the main channel and branches connect, and by changing the local flow resistance before and after the bifurcation, achieves regulation (pre-pressure adjustment) of the fluid flow rate along the branch direction and continuing along the main channel, thereby obtaining a uniform perfusion distribution of flow velocity in each branch. This organ chip solves the problem of T-shaped or Y-shaped microchannel shunt regions occupying a large chip area, achieving uniform flow distribution in each branch within a limited space, meeting the requirements of parallel experiments, and is particularly suitable for high-throughput organoid culture experiments, significantly improving the consistency of parallel experimental conditions and data reproducibility.

[0056] The microchannel cross-sections of the inlet main channel 10, branch channel 20, and outlet main channel 30 can be of any shape (rectangular, circular), and can be selected according to different manufacturing methods. For example, CNC machining is more conducive to manufacturing rectangular channels, while 3D printing can be used to manufacture channels with various cross-sectional shapes, etc. In this embodiment, the microchannel cross-sections of the inlet main channel 10, branch channel 20, and outlet main channel 30 are all rectangular, and the inlet main channel 10, branch channel 20, and outlet main channel 30 are obtained by grooving on PMMA material using a machine tool.

[0057] All parameters of each branch 20 are identical, including length, width, and height. The length of the branch and the cross-section of the microchannel also affect the flow rate; therefore, to ensure that each branch operates under the same environment / conditions as much as possible, the parameters of each branch are completely identical. Each branch 20 has a receiving hole for insertion into the culture chamber 40, and the bottom of the receiving hole communicates with the microchannel.

[0058] In this embodiment, the width of the microchannel cross-section of the branch 20 is gradually changed in order to fit the culture chamber 40.

[0059] The parallel multi-organ chip is a single unit, comprising a main body and a pressure-sensitive membrane sealed to the bottom of the main body. However, based on the positions of the microchannels (inlet main channel 10, branch channel 20, and outlet main channel 30) and the inserted culture chamber 40, it can be considered as an upper and lower two-layer structure of microchannels and culture chamber 40. Specifically, the culture chamber 40 is used for organoid culture. Its bottom is equipped with a porous membrane. When the culture chamber 40 is inserted, the porous membrane at the bottom of the culture chamber 40 is flush with the upper wall of the microchannel, forming a sealed interface with the flow channel. Therefore, liquid cannot directly "flow out" from the bottom of the accommodating hole. The liquid still flows along the main and branch channels of the microchannel and exchanges substances with the cells in the chamber through the porous membrane. The porous membrane allows for substance exchange between the culture medium and the organoids, while simultaneously isolating different components to avoid direct liquid flow impact, providing a microenvironment closer to the real physiological environment. In other words, the upper wall of the microchannel is used as the dividing line (this dividing line is imaginary). Below the dividing line, there is the microchannel located at the bottom of the chip; above the dividing line, there is the receiving hole for inserting the culture chamber 40, as well as the liquid inlet 11, the sample dispensing port 12, the liquid outlet 31, and the sampling port 32.

[0060] The main body of the parallel multi-organ chip is made of PMMA, and the parallel multi-organ chip is machined as a single unit using a machine tool.

[0061] On the other hand, the present invention provides a method for fabricating parallel multi-organ chips, which is based on the microfluidic-circuit analogy and includes:

[0062] Step S1: Initially construct the structural model of the parallel multi-organ chip and determine the arrangement of microchannels such as the inlet main channel 10, the multiple parallel branches 20, and the outlet main channel 30;

[0063] The parallel multi-organ chip includes sequentially connected microchannels such as an inlet main channel 10, multiple parallel branches 20, and an outlet main channel 30. The inlet main channel 10 connects to the inlets of each parallel branch 20 through various bifurcation points, and the outlet main channel 30 connects to the outlets of each parallel branch 20 through various bifurcation points. In the preliminary structural model of the multi-organ chip, the cross-sectional areas of the microchannels in the inlet main channel 10 and the outlet main channel 30 are fixed values.

[0064] Step S2: As Figure 3 As shown, the current resistance of each microchannel is equivalent to a resistor in order to establish an analog circuit model.

[0065] like Figure 3 As shown, after equating the flow resistance of each microchannel to a resistor, the perfusion device is also analogized to a current source I1 to establish an analog circuit model.

[0066] Specifically, the flow resistance of each segment of the inlet main channel 10 separated by the bifurcation point is equivalent to multiple resistors, the flow resistance of each branch 20 is equivalent to multiple resistors, and the flow resistance of each segment of the outlet main channel 30 separated by the bifurcation point is equivalent to multiple resistors.

[0067] In this embodiment, since there are 5 branches 20, the inlet main channel 10 is divided into 5 segments and the flow resistance of each segment is equivalent to resistors R1 to R5 respectively; the 5 branches 20 are equivalent to resistors R6 to R10 respectively. Since the five branches are exactly the same, the resistance values ​​of resistors R6 to R10 are also the same; the outlet main channel 30 is divided into 5 segments and the flow resistance of each segment is equivalent to resistors R11 to R15 respectively.

[0068] Step S3: In the analog circuit model, the current of each branch 20 is equal (i.e., the flow rate is uniform) is set as the optimization goal, so as to optimize the resistance of each segment and each branch 20 of the inlet main channel 10 and outlet main channel 30 separated by each bifurcation point, which is then equivalent to the flow resistance of each segment.

[0069] In this embodiment, the optimization objective is to ensure that the current in each branch 20 is equal, that is, to ensure that the liquid flow rate in each branch is uniform, i.e., Q. i =Q 总 / n, where n is the number of branches, and n is any integer. In this embodiment, the number of branches 20 is n=5, that is, five branches 20 are used as an example, but the present invention is not limited to five branches 20.

[0070] Step S4: As Figure 4 As shown, the geometric parameters of the microchannel are derived by using the Hagen-Poiseuille formula based on the flow resistance of each segment. Based on these geometric parameters, the geometric parameters of the microchannels in the parallel multi-organ chip structural model are adjusted so that the cross-section of the microchannel in the inlet channel 10 decreases stepwise at each bifurcation point except for the first bifurcation point along the liquid flow direction, thereby increasing the flow resistance. Similarly, the cross-section of the microchannel in the outlet channel 30 increases stepwise at each bifurcation point except for the last bifurcation point along the liquid flow direction, thereby decreasing the flow resistance.

[0071] Considering that branch 20 has a receiving hole for inserting culture chambers, the receiving hole affects the flow resistance of branch 20, but the effect is minimal. The porous membrane at the bottom of the chamber may introduce local disturbances and affect the flow resistance of the branch. Furthermore, the deformation and mass exchange characteristics of the elastic membrane itself make its specific flow resistance difficult to calculate. To accurately obtain its flow resistance, CFD simulation can be performed using software such as COMSOL Multiphysics to obtain its pressure drop. and traffic To calculate the effective flow resistance In this invention, since the analog circuit method is used to guide the direction of flow channel size modification, the flow resistance error caused by the porous membrane in the branch can be resolved in the subsequent fine-tuning steps. Therefore, the flow resistance error introduced by the porous membrane can be ignored here, and the flow resistance of the branch is calculated by treating the branch as a rectangular flow channel.

[0072] In this invention, the branch structure is designed to remain unchanged according to the application requirements. Based on this, the main channel is designed. Then, the manufacturing steps in this invention are used to adjust the dimensions of the main channel structure to achieve uniform liquid flow in the branch channels.

[0073] The geometric parameters of a microchannel are determined by inverse calculation using the Hagen-Poiseuille formula based on flow resistance and target flow rate. These geometric parameters include the width and height of the microchannel.

[0074] In this embodiment, the cross-section of the microchannel is rectangular, and the formula for calculating the flow resistance is:

[0075] ,

[0076] Where w is the width of the microchannel, h is the height of the microchannel, μ is the dynamic viscosity of the liquid, and l is the length of the microchannel.

[0077] In addition, the geometric parameters of the microchannels need to conform to the actual situation. Therefore, the constraints on the geometric parameters of the microchannels include: the channel width of the microchannel cannot overlap with other microchannels; the height of the microchannel cannot exceed the total height of the chip, etc.

[0078] Step S5 (optional): Use simulation software (such as COMSOL) to perform fluid simulation verification on the structural model of the parallel multi-organ chip, and make structural fine-tuning based on the simulation results to obtain a structural model of the parallel multi-organ chip that satisfies uniform flow distribution.

[0079] Since the analogy method in steps S2-S4 is calculated under completely ideal conditions, it does not take into account the existence of dead corners, the formation of micro-vortices, and the potential for other boundary effects caused by protrusions in the actual flow channel. Therefore, steps S2-S4 only guide the direction of adjusting the flow channel size (whether to increase or decrease the width, or increase or decrease the height, and by approximately how much). After adjusting the size according to the analogy method, simulation can be performed as needed to get closer to the actual results, and then fine-tuning can be used to ensure the actual accuracy.

[0080] Step S5 specifically includes:

[0081] Step S51: Observe and determine the flow error of each branch based on the simulation results. The target flow of all five branches should be Q. 总 / 5, observe whether the flow rate is too high or too low.

[0082] Step S52: Determine the cause of uneven flow;

[0083] To determine the cause of uneven flow, the following should be assessed for each segment of the inlet main channel 10 and the outlet main channel 30 at each branch point: 1) Is the protrusion size insufficient, resulting in low flow resistance? 2) Is the channel width / height too wide? 3) Is a certain section of the main channel too narrow, resulting in insufficient pressure difference? 4) Observe the inlet of each branch channel for local acceleration / stagnant flow / backflow / vortex problems by using the velocity vector field and pressure contour lines.

[0084] Step S53: Fine-tune the structure of the microchannels based on the judgment results;

[0085] In this invention, structural fine-tuning, where the error is small, primarily involves altering the geometric dimensions of the microchannels. Only the width and / or height of the segments separating the inlet and outlet channels 10 and 30 at each bifurcation point are changed to achieve this fine-tuning, ensuring consistency with the geometric parameters of the flow channels modified before simulation. Specifically, for branches with higher flow rates: the geometric parameters (height or width) at the branch inlet are reduced; for branches with lower flow rates: the geometric parameters (height or width) at the branch inlet are slightly increased.

[0086] Step S54: Return to step S51 to perform simulation and fine-tuning iterations until the error is <5%, at which point the design is considered to have met the requirements and the process ends.

[0087] For example, the size error in the first fine-tuning is 100um, the second is 50um, and so on. With each iteration, the size error becomes smaller and more precise.

[0088] Step S6: Based on the structural model of the parallel multi-organ chip, fabricate the corresponding parallel multi-organ chip.

[0089] Step S6 specifically includes:

[0090] PMMA material is used as the main body of the parallel multi-organ chip. The microchannels located at the bottom of the chip and the receiving holes for inserting culture chambers 40, as well as the liquid inlet 11, sample inlet 12, liquid outlet 31 and sampling port 32 are obtained by integrated machining on a machine tool. The receiving holes on the branch 20 are used to insert culture chambers 40 to culture organoids. After the main body is processed, the bottom of the main body is sealed with a pressure-sensitive membrane, so that the pressure-sensitive membrane is used as the lower wall to form a closed microchannel, ensuring good sealing of the liquid perfusion system.

[0091] Based on the parallel multi-organ chip fabrication method described above, the usage method of the realized parallel multi-organ chip includes:

[0092] Step A1: Add the required culture medium through the liquid inlet, and then insert the culture chamber 40 into the receiving hole of the branch 20. Add the required culture medium and organoids into the culture chamber 40 according to the experimental requirements.

[0093] To conduct organoid interconnection culture experiments, two chambers containing different organoids can be placed on the same branch.

[0094] Step A2: Connect the parallel multi-organ chip to the perfusion device, thereby using the perfusion device as a drive to realize the fluid self-circulation of the parallel multi-organ chip.

[0095] Experimental results:

[0096] Experiment 1: such as Figure 2 As shown, the parallel multi-organ chip of the present invention changes the flow resistance by changing the local width of the flow channel, thereby achieving uniform flow distribution.

[0097] The height of the microchannels is uniformly 1mm. The width of the inlet channel 10 remains unchanged at 5mm before and after the first bifurcation point; the width of the inlet channel 10 decreases to 4mm after the second bifurcation point; the width of the inlet channel 10 decreases to 3mm after the third bifurcation point; and the width of the inlet channel 10 decreases to 2mm after the fourth bifurcation point.

[0098] The liquid outlet channel 30 is formed from the outlet of the first branch 20. The liquid outlet channel 30 starts from the outlet of the first branch 20 with a width of 2mm. After passing the second bifurcation point, the width of the liquid outlet channel 30 increases to 3mm. After passing the third bifurcation point, the width of the liquid outlet channel 20 increases to 4mm. After passing the fourth bifurcation point, the width of the liquid outlet channel 30 increases to 5mm. After passing the fifth bifurcation point, the width of the liquid outlet channel 30 remains unchanged and continues to maintain a width of 5mm.

[0099] The five parallel branches 20 are each 2 mm wide at the inlet and outlet, and each branch 20 is 28 mm long. Within each branch 20, according to the liquid flow direction, the flow channel width of the branch 20 first gradually expands from 2 mm at the inlet to 9 mm to accommodate a culture chamber with a diameter of 9 mm. The 9 mm wide section is 13.5 mm long, and then gradually narrows to 2 mm to reach the 0 outlet of the branch 20.

[0100] Figure 6 The simulation results of the parallel multi-organ chip are shown in the figure. It can be seen that the fluid flow in each branch is uniform.

[0101] Experiment 2: For example Figure 5 As shown, the parallel multi-organ chip of the present invention changes the flow resistance by changing the local height of the flow channel, thereby achieving uniform flow distribution.

[0102] The width of the inlet channel 10 remains constant at 5 mm. The height of the inlet channel 10 before and after the first bifurcation point remains constant at 1 mm. After the second bifurcation point, the height of the inlet channel 10 decreases to 0.85 mm. After the third bifurcation point, the height of the inlet channel 10 decreases to 0.73 mm. After the fourth bifurcation point, the width of the inlet channel 10 decreases to 0.60 mm.

[0103] The main outlet channel 30 is formed from the outlet of the first branch 20. The width of the main outlet channel 30 is always 5mm. The height of the main outlet channel 30 is 0.60mm from the outlet of the first branch 20. After passing the second bifurcation point, the height of the main outlet channel 30 increases to 0.73mm. After passing the third bifurcation point, the height of the main outlet channel 30 increases to 0.85mm. After passing the fourth bifurcation point, the height of the main outlet channel 30 increases to 1mm. After passing the fifth bifurcation point, the height of the main outlet channel 30 remains unchanged and remains at 1mm thereafter.

[0104] The height of the five parallel branches 20 is 1 mm, the width at the inlet and outlet is 2 mm, and the length of each branch is 28 mm. In each branch, according to the liquid flow direction, the channel width first expands from 2 mm at the inlet to 9 mm to fit a culture chamber with a diameter of 9 mm. The 9 mm wide section is 13.5 mm long, and then gradually shrinks to 2 mm to reach the branch outlet.

[0105] Figure 7 The simulation results of the parallel multi-organ chip are shown in the figure. It can be seen that the fluid flow in each branch is uniform.

[0106] The parallel multi-organ-on-a-chip of the present invention can achieve uniform perfusion in five channels with only one liquid driving source, which significantly reduces the number of perfusion modules, lowers system complexity and usage threshold, and facilitates the promotion of high-throughput organ-on-a-chip platforms.

[0107] The parallel multi-organ chip of this invention achieves uniform current distribution by controlling the channel geometry dimensions. The structure is simple and highly controllable, with low manufacturing costs. Precise flow resistance matching can be achieved directly through dimensional design, avoiding complex external control systems. Furthermore, uniform current distribution is achieved only by changing local dimensions, resulting in a simple structure that eliminates the need for additional chip area to set up microchannels (T-type and Y-type) for current distribution, thus saving chip area.

[0108] The parallel multi-organ chip of the present invention can be expanded to a shunt chip with any number of branches, and has good versatility and scalability. It is particularly suitable for the design of highly integrated microfluidic chips under space-constrained conditions, and can also be widely used in other biochip systems that require fluid flow consistency control.

[0109] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of the invention. Various variations can be made to the above embodiments of the present invention. All simple and equivalent changes and modifications made in accordance with the claims and description of this application fall within the protection scope of the claims of this patent. All aspects not described in detail in this invention are conventional technical content.

Claims

1. A parallel multi-organ chip, characterized in that, It includes microchannels such as the inlet main channel, multiple parallel branches, and the outlet main channel, which are connected in sequence. The inlet main channel connects to the inlet of each parallel branch through each branch point, and the outlet main channel connects to the outlet of each parallel branch through each branch point. The cross-section of the microchannel in the inlet channel decreases in a stepwise manner along the direction of liquid flow, except for the first bifurcation point, which increases the flow resistance; the cross-section of the microchannel in the outlet channel increases in a stepwise manner along the direction of liquid flow, except for the last bifurcation point, which decreases the flow resistance.

2. The parallel multi-organ chip according to claim 1, characterized in that, The inlet and outlet channels each include a branch start point interface segment and a branch end point interface segment that are sequentially connected to each branch through multiple bifurcation points. Both the branch start point interface segment and the branch end point interface segment are straight lines.

3. The parallel multi-organ chip according to claim 2, characterized in that, The starting and ending interface segments of each branch are perpendicular to all branches, and the liquid flow direction within the starting and ending interface segments is the same; all parameters of each branch are consistent.

4. The parallel multi-organ chip according to claim 1, characterized in that, Determine the geometric parameters of the microchannels in the inlet and outlet channels, including determining the flow resistance of each section based on the uniform flow rate of each branch, and then deriving the geometric parameters of the microchannels in reverse. The flow resistance of each segment is determined based on the uniform flow rate of each branch, including: equating the flow resistance of each microchannel to a resistor in order to establish an analog circuit model. In the analog circuit model, the optimization objective is to make the current in each branch equal to calculate the resistance of each segment and branch of the inlet and outlet main channels that are separated by each bifurcation point, and then convert it into the flow resistance of each segment.

5. The parallel multi-organ chip according to claim 1, characterized in that, The liquid inlet channel is provided with a liquid inlet and a sample inlet connected to it above the liquid inlet channel, and the liquid outlet channel is provided with a liquid outlet and a sample inlet connected to it above the liquid outlet channel. The branch is provided with a receiving hole for inserting into the culture chamber, and the bottom of the receiving hole is connected to the microchannel.

6. The parallel multi-organ chip according to claim 1, characterized in that, The parallel multi-organ chip includes an integral main body and a pressure-sensitive membrane sealed to the bottom of the main body.

7. A method for fabricating a parallel multi-organ-on-a-chip, characterized in that, include: Step S1: Initially construct the structural model of the parallel multi-organ chip and determine the arrangement of microchannels such as the inlet main channel, multiple parallel branches, and the outlet main channel; The parallel multi-organ chip includes microchannels such as an inlet main channel, multiple parallel branches, and an outlet main channel connected in sequence. The inlet main channel connects to the inlets of the parallel branches in sequence through various bifurcation points, and the outlet main channel connects to the outlets of the parallel branches in sequence through various bifurcation points. Step S2: Equivalent the current resistance of each microchannel to a resistor to establish an analog circuit model; Step S3: In the analog circuit model, set the current of each branch to be equal as the optimization goal, so as to optimize the resistance of each segment and branch of the inlet and outlet main channels separated by each bifurcation point, and then convert it into the flow resistance of each segment. Step S4: Using the Hagen-Poiseuille formula, the geometric parameters of the microchannel are derived from the flow resistance of each segment. Based on the geometric parameters of the microchannel, the geometric parameters of the microchannel in the parallel multi-organ chip structure model are adjusted so that the cross-section of the microchannel in the inlet channel decreases stepwise at each bifurcation point along the liquid flow direction except for the first bifurcation point, thereby increasing the flow resistance; the cross-section of the microchannel in the outlet channel increases stepwise at each bifurcation point along the liquid flow direction except for the last bifurcation point, thereby decreasing the flow resistance. Step S6: Based on the structural model of the parallel multi-organ chip, fabricate the corresponding parallel multi-organ chip.

8. The method for fabricating parallel multi-organ-on-a-chip according to claim 7, characterized in that, The geometric parameters of the microchannel include the width and height of the microchannel; The constraints on the geometric parameters of microchannels include: the channel width of a microchannel cannot overlap with other microchannels; and the height of a microchannel cannot exceed the total height of the chip.

9. The method for fabricating parallel multi-organ-on-a-chip according to claim 7, characterized in that, Step S6 specifically includes: PMMA material is used as the main body of the parallel multi-organ chip. The microchannels located at the bottom of the chip and the accommodating holes for inserting the culture chamber, as well as the liquid inlet, sample outlet, liquid outlet and sampling port are located above the microchannels through integrated machine tool processing. After the main body is processed, the bottom of the main body is sealed with a pressure-sensitive membrane.

10. The method for fabricating parallel multi-organ-on-a-chip according to claim 7, characterized in that, After step S4 and before step S6, the method further includes: using simulation software to perform fluid simulation verification on the structural model of the parallel multi-organ chip, and fine-tuning the structure based on the simulation results to obtain a structural model of the parallel multi-organ chip that satisfies uniform flow distribution.

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