A microfluidic chip design method based on fluidic choke criteria

Abstract

The application discloses a microfluidic chip design method based on a fluid jamming criterion, comprising the following steps: constructing a geometric model of a pore throat channel; constructing a mathematical physics model for analyzing whether fluid jamming occurs in the pore throat channel according to the geometric model of the pore throat channel and in combination with fluid physical properties of the pore throat channel; deriving a fluid jamming criterion according to the mathematical physics model; and establishing a microfluidic chip design method based on the fluid jamming criterion. The fluid jamming criterion constructed by the application is intuitive, simple, accurate, and has strong universality and wide application scenarios. The pore throat depth is compared with the throat width, the curvature radius and the pore width, so as to determine whether the pore throat will cause fluid jamming and under what conditions the fluid jamming occurs. The application can effectively solve the problem of designing a microfluidic chip with the function of realizing / avoiding fluid jamming.

Description

Technical Field

[0001] This invention relates to the fields of fluid mechanics and microfluidics, and in particular to a microfluidic chip design method based on fluid breakage criteria. Background Technology

[0002] The displacement of the non-wetting fluid by the wetting fluid in the pore throat channel causes the non-wetting fluid to split into individual fluids / bubbles; this phenomenon is called jamming. The jamming effect occurs when the capillary pressure at the front end of the non-wetting fluid exceeds the capillary pressure at the pore throat connection during the displacement process of the wetting fluid.

[0003] Microfluidics is an advanced technology that precisely manipulates and controls microfluidics through microchannels. As microfluidic chips undertake increasingly diverse functions, the structural design of their internal microchannels has become increasingly complex. Pore-throat channels are increasingly used in microfluidic chip design, leading to a growing prevalence of fluid jamming within these chips. On one hand, applications such as single-cell fluid encapsulation, emulsion preparation, and bubble generation require the application of fluid jamming effects; on the other hand, applications such as sheath flow focusing, substance extraction, and chemical reactions require the avoidance of these effects. However, the conditions under which fluid jamming occurs in microfluidic pore-throat channels remain controversial. Furthermore, there is currently no effective criterion or method to achieve precise fluid jamming through the geometric design of microfluidic channels.

[0004] Therefore, quantitatively and accurately characterizing the channel geometry criteria satisfied by fluid jamming in the pore throat channel and constructing a set of microfluidic chip design methods to effectively realize fluid jamming is beneficial for microfluidic chips to accurately realize or avoid fluid jamming effects, thereby better meeting the application needs of microfluidic chips in life sciences, medical and health, energy development, environmental monitoring and other fields with higher precision and wider range. Summary of the Invention

[0005] This invention addresses the problem that conventional microfluidic chip design methods cannot accurately achieve / avoid fluid jamming effects in orifice throat channels. It provides a microfluidic chip design method based on a fluid jamming criterion. The fluid jamming criterion involved in this method can be used to determine under what conditions fluid jamming can occur in a microfluidic chip, and can also be applied to designing microfluidic chips with functions to achieve / avoid fluid jamming. The fluid jamming criterion is intuitive, simple, highly accurate, and widely applicable. It also avoids the limitations imposed by conventional microfluidic chip design methods on chip materials, fluid properties, and fabrication processes, unifying the debate regarding under what conditions fluid jamming can occur in orifice throat channels, and effectively solving the design problem of microfluidic chips with functions to achieve / avoid fluid jamming.

[0006] To address the aforementioned technical problems, embodiments of the present invention provide the following solutions:

[0007] A microfluidic chip design method based on fluid breakage criteria includes the following steps:

[0008] S1. Construct the geometric model of the orifice throat channel;

[0009] S2. Based on the geometric model of the orifice throat channel and combined with the fluid physical characteristics of the orifice throat channel, construct a mathematical and physical model for analyzing whether fluid gets stuck in the orifice throat channel.

[0010] S3. Derive the fluid jamming criterion based on the mathematical and physical model described above;

[0011] S4. Establish a microfluidic chip design method based on the fluid breakage criterion.

[0012] Preferably, in step S1, the pore throat channel is a rectangular cross-section pore throat channel, which includes a pore, a throat, a tapering, and a widening; the geometric parameters of the pore throat channel include: pore throat depth h, throat width R. t pore width R p The principal curvature circle of the larynx, the radius of the principal curvature of the larynx R o .

[0013] Preferably, in step S2, the fluid physical properties of the pore throat channel include the interfacial tension coefficient σ at the interface between the wetting fluid and the non-wetting fluid, and the contact angle θ of the wetting fluid.

[0014] When the capillary pressure P in the larynx c-neck The capillary pressure P at the non-wetting fluid front is greater than c-front A block can only occur when the time is right; otherwise, a block will not occur.

[0015] The P mentioned c-front Numerically equal to the capillary pressure in the pores; the P c-neck and P c-front According to the Young-Laplace equation:

[0016]

[0017]

[0018] In the formula, r xoy-neck It is the principal radius of curvature of the fluid interface on the xoy section at the throat; r yoz-neck It is the principal radius of curvature of the fluid interface on the yoz section at the throat; r xoy-front It is the principal radius of curvature of the fluid interface on the xoy section at the pore where the non-wetting fluid front is located; r yoz-front It is the principal radius of curvature of the fluid interface on the yoz section at the pore where the non-wetting fluid front is located;

[0019] When the capillary pressure difference ΔP between the throat and the pore satisfies:

[0020] ΔP=P c-neck -P c-front >0

[0021] Fluid flow is interrupted in the orifice throat channel; conversely, it is not interrupted.

[0022] Preferably, step S3 specifically includes:

[0023] Based on the throat depth h relative to the throat width R t and pore width R p The size is divided into the following three working conditions:

[0024] Operating condition 1: When h < 2R t At that time, the capillary pressure difference between the throat and the pore is:

[0025]

[0026] The capillary pressure difference P between the throat and the pore in operating condition 1 c-neck -P c-front Since h is always less than zero, we obtain criterion 1 for determining the conditions under which fluid will become stuck in a rectangular cross-section orifice throat: when h < 2R. t At this time, the fluid in the orifice throat channel will not be blocked;

[0027] Operating Condition 2: When 2R t ≤h<2R p At that time, the capillary pressure difference between the throat and the pore is:

[0028]

[0029] Let P c-neck -P c-front =0, to obtain the critical throat depth h at which fluid in the throat channel will be blocked. c :

[0030]

[0031] The capillary pressure difference P between the throat and the pore c-neck -P c-front Less than zero, thus we obtain criterion 2 for determining the conditions under which fluid will become stuck in a rectangular cross-section orifice throat: when 2R t ≤h<2R p , and h c ≤h<2R p At this time, the fluid in the orifice throat channel can be blocked; when 2R t ≤h<2R p And 2Rt <h<h c At that time, the fluid in the orifice throat channel must not be blocked;

[0032] Operating condition 3: When h > 2R p At that time, the capillary pressure difference between the throat and the pore is:

[0033]

[0034] Whether fluid can become stuck in the orifice throat channel in operating condition 3 is independent of the orifice throat depth h, but depends on the throat width R. t Related; the capillary pressure difference P between the throat and the pores c-neck -P c-front Less than zero, thus we obtain criterion 3 for determining the conditions under which fluid will become stuck in the throat of a rectangular cross-section orifice:

[0035] when At that time, the fluid in the orifice throat channel can become blocked; when At that time, the fluid in the orifice throat channel must not be blocked;

[0036] The criteria 1, criterion 2 and criterion 3 derived under the above three working conditions constitute the fluid jamming criteria.

[0037] Preferably, step S4 specifically includes:

[0038] When designing microfluidic chips, based on the fluid cutoff criterion, the orifice throat channel must meet at least one of the following conditions to achieve fluid cutoff:

[0039] Condition 1-1, let h < 2R t ;

[0040] Conditions 1-2, let 2R t ≤h<2R p And h c ≤h<2R p ;

[0041] Conditions 1-3, let h > 2R p and

[0042] In scenarios where fluid blockage is to be avoided, the orifice throat channel must meet at least one of the following conditions:

[0043] Condition 2-1, let 2R t <h<2R p And 2R t <h<h c ;

[0044] Condition 2-2, let h > 2R p and

[0045] Wherein, h c The critical throat depth at which fluid in the pore throat channel may become blocked.

[0046] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following:

[0047] (1) The method of the present invention constructs a simple and effective fluid jamming criterion, which only requires the orifice throat depth h and throat width R to be compared. t radius of curvature R o and pore width R p By comparing the results, it is possible to determine whether the orifice throat will cause fluid blockage and under what conditions fluid blockage will occur. This method is highly universal and applicable to a wide range of scenarios.

[0048] (2) The present invention proposes a microfluidic chip design calculation method with the function of realizing / avoiding fluid jamming. For the application scenario of realizing fluid jamming, it can calculate the throat depth h and throat width R. t radius of curvature R o and pore width R p The geometric relationships that must be satisfied between them; for applications that prevent fluid blockage, the orifice throat depth h and throat width R can be calculated. t radius of curvature R o and pore width R p The geometric relationship that must be satisfied between them.

[0049] (3) The present invention introduces a three-dimensional pore-throat geometry-capillary pressure difference correlation calculation method. In view of the strong empirical nature and condition simplification of the traditional pore-throat capillary pressure difference calculation method, the analytical expression of the fluid jamming criterion is obtained by solving and sorting from the fluid mechanics mechanism, which ensures the high accuracy and physical interpretability of the fluid jamming criterion on which the method is based. Attached Figure Description

[0050] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0051] Figure 1 This is a flowchart of a microfluidic chip design method based on fluid breakage criteria provided in an embodiment of the present invention;

[0052] Figure 2a and Figure 2b These are a three-dimensional schematic diagram and a planar schematic diagram of the aperture throat channel structure in the microfluidic chip provided in the embodiments of the present invention;

[0053] Figure 3a and Figure 3b This is a schematic diagram illustrating the fluid flow in the orifice throat channel under conditions of both jamming and non-jamming, as provided in an embodiment of the present invention.

[0054] Figure 4 This is a cross-sectional schematic diagram of the fluid in the pore throat channel provided in an embodiment of the present invention.

[0055] As shown in the figure, specific structures and devices are marked in the figure to clearly illustrate the structure of the embodiments of the present invention. However, this is only for illustrative purposes and is not intended to limit the present invention to the specific structure, device and environment. According to specific needs, those skilled in the art can adjust or modify these devices and environments, and such adjustments or modifications are still included in the protection scope of the present invention. Detailed Implementation

[0056] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0057] Embodiments of the present invention provide a microfluidic chip design method based on the fluid breakage criterion, such as... Figure 1 As shown, the method includes the following steps:

[0058] S1. Construct the geometric model of the orifice throat channel.

[0059] Taking a rectangular cross-section orifice throat channel as an example, refer to Figure 2a and Figure 2b The pore-throat channel 1 includes an pore 2, a throat 3, a tapering 4, and a widening 5; the geometric parameters of the pore-throat channel 1 include: pore-throat depth 6 (h), throat width 7 (R). t ), pore width 8 (R) p The principal curvature circle of the larynx is 9, and the radius of curvature of the principal curvature of the larynx is 10 (R). o ).

[0060] It should be noted that the throat channel described in step S1 is not limited to a rectangular cross-section. Step S1 only uses a throat channel with a rectangular cross-section as an example. In practical applications, the present invention is still applicable to throat channels with any geometric cross-section.

[0061] Furthermore, the aforementioned throat channel 1 is a microchannel structure inside a microfluidic chip, and its size is generally on the order of 1 micrometer to 1000 micrometers.

[0062] Furthermore, the throat channel 1 is as shown in the attached... Figure 2a The region with the longest length in the y-direction shown is pore 2; the pore throat channel 1 is as shown in the attached figure. Figure 2a The region with the shortest length in the y-direction shown is the throat 3; the orifice-throat passage 1 is as shown in the attached figure. Figure 2a The region in the x-direction connecting the pore 2 and the throat 3 is the tapering 4; the pore-throat channel 1 is as shown in the attached figure. Figure 2a The region in the x-direction that connects throat 3 and pore 2 is called the gradually expanding 5.

[0063] The principal curvature circle 9 of the larynx refers to the circle along the larynx. Figure 2b The circle of curvature corresponding to the point of maximum curvature among all cross sections along the x-axis.

[0064] Furthermore, the principal curvature radius of the larynx is 10(R) o ) is the radius of the principal curvature circle 9 of the throat.

[0065] S2. Based on the geometric model of the orifice throat channel and combined with the fluid physical characteristics of the orifice throat channel, construct a mathematical and physical model for analyzing whether fluid gets stuck in the orifice throat channel.

[0066] Taking a rectangular cross-section pore-throat channel as an example, the fluid physical properties of the pore-throat channel include the interfacial tension coefficient σ at the interface between the wetting fluid and the non-wetting fluid, and the contact angle θ of the wetting fluid. Only when the capillary pressure P at the throat... c-neck The capillary pressure P at the non-wetting fluid front is greater than c-front Only when the card breaks can this happen. For example... Figure 3a and Figure 3b As shown, before passing through the throat (shown as label 15), the pressure inside the non-wetting fluid is uniform and equal to P. c-front When passing through the throat (shown as 16), the capillary pressure P experienced by the unwetting fluid front that has left the throat is relatively small. c-front The capillary pressure P experienced by the non-wetting fluid still in the throat is relatively large. c-neck This leads to uneven pressure across the non-wetting fluid, resulting in jamming (as shown in label 17); conversely, jamming does not occur (as shown in label 18).

[0067] The P mentioned c-front Numerically equal to the capillary pressure in the pores; the P c-neck and P c-front According to the Young-Laplace equation:

[0068]

[0069]

[0070] In the formula, r xoy-neck It is the principal radius of curvature of the fluid interface on the xoy section at the throat; r yoz-neck It is the principal radius of curvature of the fluid interface on the yoz section at the throat; r xoy-front It is the principal radius of curvature of the fluid interface on the xoy section at the pore where the non-wetting fluid front is located; r yoz-front It is the principal radius of curvature of the fluid interface on the yoz section at the pore where the non-wetting fluid front is located.

[0071] When the capillary pressure difference ΔP between the throat and the pore satisfies:

[0072] ΔP=P c-neck -P c-front >0

[0073] Fluid flow is interrupted in the orifice throat channel; conversely, it is not interrupted.

[0074] S3. Derive the fluid jamming criterion based on the mathematical and physical model.

[0075] Taking a rectangular cross-section pore throat channel as an example, for a two-dimensional pore throat structure, based on the pore throat depth h relative to the throat width R... t and pore width R p The size can be specifically categorized into the following three working conditions:

[0076] Operating condition 1: When h < 2R t At that time, the capillary pressure difference between the throat and the pore is:

[0077]

[0078] It can be seen that the capillary pressure difference P between the throat and the pore in operating condition 1 c-neck -P c-front Since h is always less than zero, we obtain criterion 1 for determining the conditions under which fluid will become stuck in a rectangular cross-section orifice throat: when h < 2R. t At this time, the fluid in the orifice throat channel will not be blocked.

[0079] Operating Condition 2: When 2R t ≤h<2R p At that time, the capillary pressure difference between the throat and the pore is:

[0080]

[0081] Let P c-neck -P c-front =0, to obtain the critical throat depth h at which fluid in the throat channel will be blocked. c :

[0082]

[0083] The capillary pressure difference P between the throat and the pore c-neck -P c-front Less than zero, thus we obtain criterion 2 for determining the conditions under which fluid will become stuck in a rectangular cross-section orifice throat: when 2R t ≤h<2R p , and h c ≤h<2R p At this time, the fluid in the orifice throat channel can be blocked; when 2R t ≤h<2R p And 2R t <h<h c At that time, the fluid in the orifice throat channel must not be blocked.

[0084] Operating condition 3: When h > 2R p At that time, the capillary pressure difference between the throat and the pore is:

[0085]

[0086] It can be seen that whether the fluid in the orifice throat channel can become stuck in working condition 3 is independent of the orifice throat depth h, but independent of the throat width R. t Related; the capillary pressure difference P between the throat and the pores c-neck -P c-front Less than zero, thus we obtain criterion 3 for determining the conditions under which fluid will become stuck in the throat of a rectangular cross-section orifice:

[0087] when At that time, the fluid in the orifice throat channel can become blocked; when At that time, the fluid in the orifice throat channel must not be blocked.

[0088] The criteria 1, criterion 2 and criterion 3 derived under the above three working conditions constitute the fluid jamming criteria described in this invention.

[0089] Among them, due to the presence of non-wetting fluid in the pore throat, such as Figure 4 The wall-attached flow shown (shown as 19) in step S3 is not simply the pore throat feature scale 20, but rather the ratio of the pore throat feature scale 20 to the cosine of the wetting fluid contact angle 14 during the derivation process of step S3.

[0090] Furthermore, the yoz cross-section throat feature dimension 20, at the throat, is the throat width 7 (R) t The smallest of the values ​​of ) and throat depth 6(h); at the pore, it is the pore width 8(R) p The value is the smallest among the ) and the throat depth 6(h).

[0091] In step S3, since the direction of the principal curvature radius 10 of the throat's principal curvature circle 9 is perpendicular to the throat width 7 (R t ) and pore width 8 (R p The direction is opposite, and the principal curvature radius of the throat is negative.

[0092] Furthermore, the principal curvature radius 10 of the throat is negative, meaning it is far from the fluid inside the throat. Therefore, the principal curvature radius 10 of the throat does not need to be transformed based on the cosine value of the wetting fluid contact angle 14.

[0093] S4. Establish a microfluidic chip design method based on the fluid breakage criterion.

[0094] When designing microfluidic chips, based on the fluid cutoff criterion, the orifice throat channel must meet at least one of the following conditions to achieve fluid cutoff:

[0095] Condition 1-1, let h < 2R t ;

[0096] Conditions 1-2, let 2R t ≤h<2R p And h c ≤h<2R p ;

[0097] Conditions 1-3, let h > 2R p and

[0098] Wherein, h c The critical throat depth for determining whether fluid blockage occurs in the pore throat channel is expressed as the same as the critical throat depth h for determining whether fluid blockage occurs in the pore throat channel in step S3. c The expressions are the same.

[0099] In scenarios where fluid blockage is to be avoided, the orifice throat channel must meet at least one of the following conditions:

[0100] Condition 2-1, let 2R t <h<2R p And 2R t <h<h c ;

[0101] Condition 2-2, let h > 2R p and

[0102] The h mentioned c The critical throat depth for determining whether fluid blockage occurs in the pore throat channel is expressed as the same as the critical throat depth h for determining whether fluid blockage occurs in the pore throat channel in step S3. c The expressions are the same.

[0103] In this embodiment of the invention, a simple and effective fluid jamming criterion is constructed, which only requires comparing the orifice throat depth h with the throat width R. t radius of curvature R o and pore width R p By comparing the results, it is possible to determine whether the orifice throat will cause fluid blockage and under what conditions fluid blockage will occur. This method is highly universal and applicable to a wide range of scenarios.

[0104] The fluid jamming criterion described is intuitive, simple, highly accurate, and universally applicable. It also avoids the limitations imposed by conventional microfluidic chip design methods on chip materials, fluid properties, and fabrication processes. It unifies the controversy regarding the conditions under which fluid jamming can occur in the orifice throat channel, and can effectively solve the design problem of microfluidic chips with the function of realizing / avoiding fluid jamming.

[0105] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or terminal device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or terminal device. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or terminal device that includes said element.

[0106] The use of terms such as "an embodiment," "an embodiment," "an exemplary embodiment," and "some embodiments" in the specification indicates that the described embodiment may include a specific feature, structure, or characteristic, but not every embodiment necessarily includes that specific feature, structure, or characteristic. Furthermore, when a specific feature, structure, or characteristic is described in connection with an embodiment, implementing such a feature, structure, or characteristic in conjunction with other embodiments (whether explicitly described or not) should be within the knowledge of those skilled in the art.

[0107] This invention encompasses any substitutions, modifications, equivalent methods, and solutions made within the spirit and scope of this invention. To provide the public with a thorough understanding of this invention, specific details are described in detail in the following preferred embodiments; however, those skilled in the art will fully understand the invention even without these details. Furthermore, to avoid unnecessary misunderstanding of the essence of this invention, well-known methods, processes, procedures, components, and circuits are not described in detail.

[0108] Those skilled in the art will understand that all or part of the steps in the methods of the above embodiments can be implemented by a program instructing related hardware. The program can be stored in a computer-readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc.

[0109] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A microfluidic chip design method based on fluid breakage criteria, characterized in that, Includes the following steps: S1. Construct the geometric model of the orifice throat channel; In step S1, the pore throat channel is a rectangular cross-section pore throat channel, which includes a pore, a throat, a narrowing, and a widening. The geometric parameters of the orifice-throat channel include: orifice-throat depth h, throat width R. t pore width R p The principal curvature circle of the larynx, the radius of the principal curvature of the larynx R o ; S2. Based on the geometric model of the orifice throat channel and combined with the fluid physical characteristics of the orifice throat channel, construct a mathematical and physical model for analyzing whether fluid gets stuck in the orifice throat channel. In step S2, the fluid physical properties of the pore throat channel include the interfacial tension coefficient σ at the interface between the wetting fluid and the non-wetting fluid, and the contact angle θ of the wetting fluid. When the capillary pressure P in the larynx c-neck The capillary pressure P at the non-wetting fluid front is greater than c-front A block can only occur when the time is right; otherwise, a block will not occur. The P mentioned c-front Numerically equal to the capillary pressure in the pores; the P c-neck and P c-front According to the Young-Laplace equation: In the formula, r xoy-neck It is the principal radius of curvature of the fluid interface on the xoy section at the throat; r yoz-neck It is the principal radius of curvature of the fluid interface on the yoz section at the throat; r xoy-front It is the principal radius of curvature of the fluid interface on the xoy section at the pore where the non-wetting fluid front is located; r yoz-front It is the principal radius of curvature of the fluid interface on the yoz section at the pore where the non-wetting fluid front is located; When the capillary pressure difference ΔP between the throat and the pore satisfies: ΔP=P c-neck -P c-front >0 Fluid flow is interrupted in the orifice throat channel; conversely, it is not interrupted. S3. Derive the fluid jamming criterion based on the mathematical and physical model described above; Step S3 specifically includes: Based on the throat depth h relative to the throat width R t and pore width R p The size is divided into the following three working conditions: Operating condition 1: When h < 2R t At that time, the capillary pressure difference between the throat and the pore is: The capillary pressure difference P between the throat and the pore in operating condition 1 c-neck -P c-front Since h is always less than zero, we obtain criterion 1 for determining the conditions under which fluid will become stuck in a rectangular cross-section orifice throat: when h < 2R. t At this time, the fluid in the orifice throat channel will not be blocked; Operating Condition 2: When 2R t ≤h<2R p At that time, the capillary pressure difference between the throat and the pore is: Let P c-neck -P c-front =0, to obtain the critical throat depth h at which fluid in the throat channel will be blocked. c : The capillary pressure difference P between the throat and the pore c-neck -P c-front Less than zero, thus we obtain criterion 2 for determining the conditions under which fluid will become stuck in a rectangular cross-section orifice throat: when 2R t ≤h<2R p , and h c ≤h<2R p At this time, the fluid in the orifice throat channel can be blocked; when 2R t ≤h<2R p And 2R t <h<h c At that time, the fluid in the orifice throat channel must not be blocked; Operating condition 3: When h > 2R p At that time, the capillary pressure difference between the throat and the pore is: Whether fluid can become stuck in the orifice throat channel in operating condition 3 is independent of the orifice throat depth h, but depends on the throat width R. t Related; the capillary pressure difference P between the throat and the pores c-neck -P c-front Less than zero, thus we obtain criterion 3 for determining the conditions under which fluid will become stuck in the throat of a rectangular cross-section orifice: when At that time, the fluid in the orifice throat channel can become blocked; when At that time, the fluid in the orifice throat channel must not be blocked; The criteria 1, criterion 2, and criterion 3 derived under the above three working conditions constitute the fluid jamming criteria. S4. Establish a microfluidic chip design method based on the fluid breakage criterion.

2. The microfluidic chip design method based on the fluid breakage criterion according to claim 1, characterized in that, Step S4 specifically includes: When designing microfluidic chips, based on the fluid cutoff criterion, the orifice throat channel must meet at least one of the following conditions to achieve fluid cutoff: Condition 1-1, let h < 2R t ; Conditions 1-2, let 2R t ≤h<2R p And h c ≤h<2R p ; Conditions 1-3, let h > 2R p and In scenarios where fluid blockage is to be avoided, the orifice throat channel must meet at least one of the following conditions: Condition 2-1, let 2R t <h<2R p And 2R t <h<h c ; Condition 2-2, let h > 2R p and Wherein, h c The critical throat depth at which fluid in the pore throat channel may become blocked.

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