阅读说明：本技术 一种分形阶跃通道式双重乳液微流控量产装置 (Fractal step channel type double-emulsion micro-fluidic mass production device ) 是由 陈永平 卢悦 李波 刘向东 于 2021-09-26 设计创作，主要内容包括：一种分形阶跃通道式双重乳液微流控量产装置,包括若干并行的横向渐扩-纵向突扩乳化单元和多级配置的分形结构流体分配通道,横向渐扩-纵向突扩乳化单元包括相互连接的等深度楔形流动截面渐扩结构和变深度纵向突扩阶跃结构。横向渐扩-纵向突扩乳化单元中,等深度楔形流动截面渐扩结构将流体从通道壁面推离,促进液滴在表面张力作用下加速脱离,变深度纵向突扩阶跃结构则会引起内界面拉普拉斯压差的变化,产生定向毛细驱动压差,促进流体快速流出,并在瑞利不稳定作用下断裂形成液滴,两种效应相互协同,提升乳液生成动力,串联两级乳化模块可促成双重乳液生成；分形结构流体分配通道可解决各相流体在多路并行制备单元之间出现分配不均的问题。(A fractal step channel type double-emulsion microfluidic volume production device comprises a plurality of parallel transverse divergent-longitudinal sudden-divergent emulsification units and a fractal structure fluid distribution channel in multistage configuration, wherein each transverse divergent-longitudinal sudden-divergent emulsification unit comprises an equal-depth wedge-shaped flow cross section divergent structure and a variable-depth longitudinal sudden-divergent step structure which are mutually connected. In the transverse divergent-longitudinal sudden-divergent emulsification unit, a constant-depth wedge-shaped flow cross section divergent structure pushes away fluid from the wall surface of a channel, so that the accelerated separation of liquid drops under the action of surface tension is promoted, the change of Laplace differential pressure of an inner interface is caused by a variable-depth longitudinal sudden-divergent step structure, directional capillary driving differential pressure is generated, the rapid outflow of the fluid is promoted, the fluid drops are formed by the breakage of the variable-depth longitudinal sudden-divergent step structure under the action of Rayleigh instability, the two effects are synergistic, the power for generating emulsion is improved, and the generation of double emulsion can be promoted by connecting two-stage emulsification modules in series; the fractal structure fluid distribution channel can solve the problem that each phase fluid is unevenly distributed among the multi-channel parallel preparation units.)

1. The utility model provides a fractal step channel formula double emulsion micro-fluidic volume production device which characterized in that: the device comprises a first-stage emulsification module (12), a second-stage emulsification module (13) and a double emulsion conveying channel (21), wherein the first-stage emulsification module (12) comprises a plurality of parallel first-stage emulsification units, each first-stage emulsification unit comprises an inner-phase fluid conveying channel (121), a first-stage constant-depth wedge-shaped flow cross section divergent structure (122), a first-stage variable-depth longitudinal sudden-expansion stepped structure (123) and an intermediate-phase fluid conveying channel (124), an outlet of the inner-phase fluid conveying channel (121) is connected with an inlet of the first-stage constant-depth wedge-shaped flow cross section divergent structure (122), an outlet of the first-stage constant-depth wedge-shaped flow cross section divergent structure (122) is connected with an inlet of the first-stage variable-depth longitudinal sudden-expansion stepped structure (123), and the intermediate-phase fluid conveying channel (124) is communicated with the bottom of the first-stage variable-depth longitudinal sudden-expansion stepped structure (123), the second-stage emulsification module (13) comprises a plurality of parallel second-stage emulsification units, each second-stage emulsification unit comprises a second-stage equal-depth wedge-shaped flow section divergent structure (131), a second-stage variable-depth longitudinal sudden-expansion step structure (132) and an outer-phase fluid conveying channel (133), an outlet of the first-stage variable-depth longitudinal sudden-expansion step structure (123) is connected with an inlet of the second-stage equal-depth wedge-shaped flow section divergent structure (131), an outlet of the second-stage equal-depth wedge-shaped flow section divergent structure (131) is connected with an inlet of the second-stage variable-depth longitudinal sudden-expansion step structure (132), the outer-phase fluid conveying channel (133) is communicated with the bottom of the second-stage variable-depth longitudinal sudden-expansion step structure (132), the divergent angle beta range of the first-stage equal-depth wedge-shaped flow section divergent structure (122) and the second-stage equal-depth wedge-shaped flow section divergent structure (131) is 10-35 degrees, the depth of the first-stage variable-depth longitudinal sudden-expansion step structure (123) and the depth of the second-stage variable-depth longitudinal sudden-expansion step structure (132) are respectively at least 2 times of that of the first-stage constant-depth wedge-shaped flow cross section divergent structure (122) and that of the second-stage constant-depth wedge-shaped flow cross section divergent structure (131), and the double emulsion conveying channel (21) is connected with an outlet of the second-stage variable-depth longitudinal sudden-expansion step structure (132).

2. The minute step channel type double emulsion micro fluidic mass production device according to claim 1, wherein: the device also comprises an inner phase fluid distribution module (11) with a fractal structure, wherein the inner phase fluid distribution module (11) comprises an inner phase fluid main channel (111) and an inner phase fluid sub-channel (112) which are communicated in sequence, the inner phase fluid main channel (111) is branched to form two inner phase fluid sub-channels (112), each inner phase fluid sub-channel (112) is branched to form two inner phase fluid sub-channels of the next stage, and the two inner phase fluid sub-channels are formed until the tail end of the inner phase fluid distribution module (11) forms a 2ⁿAnd n is the fractal progression of the inner phase fluid sub-channels, and is a natural number, and the nth stage of inner phase fluid sub-channels are communicated with the inlet of the inner phase fluid conveying channel (121).

3. The minute step channel type double emulsion micro fluidic mass production device according to claim 2, wherein: length l of i-1 th stage internal phase fluid sub-channel_i-1And the length l of the i-th stage internal phase fluid sub-channel_iSatisfyHydraulic radius d of i-1 stage internal phase fluid sub-channel_i-1And the hydraulic radius d of the i-th stage inner phase fluid sub-channel_iSatisfyWherein Δ is the length fractal dimension.

4. The minute step channel type double emulsion micro fluidic mass production device according to claim 3, wherein: also includes an intermediate phase having a fractal structureThe fluid supply and distribution module (32) and the external phase fluid supply and distribution module (33), the intermediate phase fluid supply and distribution module (32) comprises an intermediate phase fluid supply channel (323), an intermediate phase fluid main channel (321) and intermediate phase fluid sub-channels (322) which are sequentially connected, the intermediate phase fluid main channel (321) is branched to form two intermediate phase fluid sub-channels (322), each intermediate phase fluid sub-channel (322) is branched to form two intermediate phase fluid sub-channels of the next stage, and the two intermediate phase fluid sub-channels are formed until the tail end of the intermediate phase fluid supply and distribution module (32) forms 2^jJ is a fractal series of the intermediate phase fluid sub-channels (322), the j-th stage of intermediate phase fluid sub-channels is connected with the inlet of the intermediate phase fluid conveying channel (124), the external phase fluid supply distribution module (33) comprises an external phase fluid supply channel (333), an external phase fluid main channel (331) and an external phase fluid sub-channel (332) which are sequentially connected, the external phase fluid main channel (331) is forked to form two external phase fluid sub-channels (332), each external phase fluid sub-channel (332) is forked to form two external phase fluid sub-channels of the next stage until the tail end of the external phase fluid supply distribution module (33) forms 2^kAnd k is a fractal series of the outer phase fluid sub-channels (332), the k-th stage of outer phase fluid sub-channels is connected with the inlet of the outer phase fluid conveying channel (133), wherein j is k is n.

5. The minute step channel type double emulsion micro fluidic mass production device according to claim 4, wherein: the internal phase fluid distribution module (11), the primary emulsification module (12) and the secondary emulsification module (13) are all arranged in the channel plate (1), the double emulsion conveying channel (21) is arranged in the cover plate (2), the internal phase fluid supply channel (31), the intermediate phase fluid supply distribution module (32) and the external phase fluid supply distribution module (33) are all arranged in the liquid supply bottom plate (3), and the cover plate (2), the channel plate (1) and the liquid supply bottom plate (3) are sequentially and hermetically connected from top to bottom.

Technical Field

The invention relates to the technical field of double-emulsion microfluidic production, in particular to a fractal step channel type double-emulsion microfluidic volume production device.

Background

Compared with a single liquid drop, the double emulsion is an emulsion drop containing smaller liquid drops, a specific shell-core structure exists inside the double emulsion, and the double emulsion is widely applied to the fields of chemistry and chemical engineering, medicines, cosmetics and the like due to the specific flexibility and controllability of the double emulsion. In traditional double emulsion preparation technologies such as a traditional stirring method, a mechanical oscillation method and the like, strong oscillation and shearing are usually accompanied in the preparation process, and double emulsions generated by the preparation methods have the problems of poor controllability, low sphericity, low dispersity and the like.

The micro-fluidic technology can realize the accurate control of the multi-phase fluid and the phase interface behavior thereof by effectively organizing the multi-phase fluid in the micro-channel. Therefore, compared with the traditional emulsion preparation technology, the double emulsion prepared by adopting the micro-fluidic technology has the advantages of good monodispersity, excellent sphericity, high controllability and the like, the raw material consumption is low, and the whole preparation process is more economic and safer.

At present, the research on the generation process of the single-channel microfluidic droplets is mature, high-quality and monodisperse single, double or even multiple emulsion droplets can be produced, and the size, the core-shell ratio and the number of inner droplets of the droplets can be continuously adjusted. However, in the process of mass production of double emulsions, the problem of uneven distribution of each phase fluid among multiple parallel preparation units occurs, and in an emulsification system of a parallel conventional flow focusing structure, when the flow rate of each phase fluid fluctuates, the size of the droplets also changes, so that the dispersion degree of the double emulsion is low. In addition, the slow flow of each phase fluid in the microfluidic device often causes the insufficient power in the coating and separation process of the phase interface at the outlet of the unit, thereby causing the failure of emulsion generation and even the channel blockage. Therefore, the uniform distribution of each phase fluid and the sufficient power of droplet generation of the preparation unit are two major bottleneck problems of the industrial mass production of high-quality double emulsions.

Disclosure of Invention

The invention aims to provide a fractal step channel type double-emulsion microfluidic volume production device combining an equal-depth wedge-shaped gradually-expanding channel structure and a variable-depth longitudinal sudden-expanding step channel structure aiming at the defects of the prior art.

In order to solve the technical problems, the invention provides the following technical scheme:

the utility model provides a fractal step channel formula double emulsion micro-fluidic volume production device which characterized in that: the double-emulsion emulsification system comprises a first-stage emulsification module, a second-stage emulsification module and a double-emulsion conveying channel, wherein the first-stage emulsification module comprises a plurality of parallel first-stage emulsification units, each first-stage emulsification unit comprises an inner-stage fluid conveying channel, a first-stage equal-depth wedge-shaped flow section gradually-expanding structure, a first-stage variable-depth longitudinal sudden-expansion step structure and an intermediate-phase fluid conveying channel, an outlet of the inner-stage fluid conveying channel is connected with an inlet of the first-stage equal-depth wedge-shaped flow section gradually-expanding structure, an outlet of the first-stage equal-depth wedge-shaped flow section gradually-expanding structure is connected with an inlet of the first-stage variable-depth longitudinal sudden-expansion step structure, the intermediate-phase fluid conveying channel is communicated with the bottom of the first-stage variable-depth longitudinal sudden-expansion step structure, the second-stage emulsification module comprises a plurality of parallel second-stage emulsification units, each second-stage emulsification unit comprises a second-stage equal-depth wedge-shaped flow section gradually-expanding structure, A second-stage variable-depth longitudinal sudden-expansion step structure and an external-phase fluid conveying channel, wherein an outlet of the first-stage variable-depth longitudinal sudden-expansion step structure is connected with an inlet of the second-stage constant-depth wedge-shaped flow cross-section gradually-expansion structure, the outlet of the second-stage constant-depth wedge-shaped flow cross section divergent structure is connected with the inlet of the second-stage variable-depth longitudinal sudden-expansion stepped structure, the outer phase fluid conveying channel is communicated with the bottom of the second-stage variable-depth longitudinal sudden-expansion step structure, the gradual-expansion angle range of the first-stage constant-depth wedge-shaped flow section gradual-expansion structure and the second-stage constant-depth wedge-shaped flow section gradual-expansion structure is 10-35 degrees, the depth of the first-stage variable-depth longitudinal sudden-expansion step structure and the depth of the second-stage variable-depth longitudinal sudden-expansion step structure are respectively at least 2 times of that of the first-stage constant-depth wedge-shaped flow section divergent structure and that of the second-stage constant-depth wedge-shaped flow section divergent structure, the double emulsion conveying channel is connected with an outlet of the two-stage variable-depth longitudinal sudden-expansion step structure.

Further, the device also comprises an internal phase fluid distribution module with a fractal structure, wherein the internal phase fluid distribution module comprises an internal phase fluid main channel and an internal phase fluid sub-channel which are sequentially communicated, and the internal phase fluid main channelThe channel branches to form two inner phase fluid sub-channels, each inner phase fluid sub-channel branches to form two inner phase fluid sub-channels of the next stage until the end of the inner phase fluid distribution channel forms 2ⁿAnd n is the fractal progression of the inner phase fluid sub-channels, and the nth stage of inner phase fluid sub-channels are communicated with the inlets of the inner phase fluid conveying channels.

Further, the length l of the i-1 st stage internal phase fluid sub-channel_i-1And the length l of the i-th stage internal phase fluid sub-channel_iSatisfyHydraulic radius d of i-1 stage internal phase fluid sub-channel_i-1And the hydraulic radius d of the i-th stage inner phase fluid sub-channel_iSatisfyWherein Δ is the length fractal dimension.

The device further comprises an intermediate phase fluid supply and distribution module and an external phase fluid supply and distribution module which are provided with fractal structures, wherein the intermediate phase fluid supply and distribution module comprises an intermediate phase fluid supply channel, an intermediate phase fluid main channel and an intermediate phase fluid sub-channel which are sequentially connected, the intermediate phase fluid main channel is forked to form two intermediate phase fluid sub-channels, each intermediate phase fluid sub-channel is forked to form two intermediate phase fluid sub-channels of the next stage until the tail end of the intermediate phase fluid supply and distribution module forms 2^jJ is the fractal series of the intermediate phase fluid sub-channels, the j-th stage intermediate phase fluid sub-channel is connected with the inlet of the intermediate phase fluid conveying channel, the external phase fluid supply distribution module comprises an external phase fluid supply channel, an external phase fluid main channel and an external phase fluid sub-channel which are sequentially connected, the external phase fluid main channel is branched to form two external phase fluid sub-channels, each external phase fluid sub-channel is branched to form two external phase fluid sub-channels of the next stage until the tail end of the external phase fluid supply distribution module forms 2^kA sub-channel of outer phase fluid, k is the fractal of the sub-channel of outer phase fluidAnd the k-th stage external phase fluid sub-channel is connected with the inlet of the external phase fluid conveying channel, wherein j is k is n.

Further, the internal phase fluid distribution module, the primary emulsification module and the secondary emulsification module are all arranged in a channel plate, the double emulsion conveying channel is arranged in a cover plate, the internal phase fluid supply channel, the intermediate phase fluid supply distribution module and the external phase fluid supply distribution module are all arranged in a liquid supply bottom plate, and the cover plate, the channel plate and the liquid supply bottom plate are sequentially connected in a sealing mode from top to bottom.

Compared with the prior art, the invention has the beneficial effects that: 1. the horizontal gradually-expanding-longitudinal sudden-expanding emulsification units in the first-stage emulsification module and the second-stage emulsification module are both constant-depth wedge-shaped flow cross section gradually-expanding and then coupled with variable-depth longitudinal sudden-expanding step structures, wherein the constant-depth wedge-shaped flow cross section gradually-expanding structures can push fluid away from the wall surface of a channel and promote accelerated separation of liquid drops under the action of surface tension; the variable-depth longitudinal sudden expansion step structure can cause the change of Laplace (Laplace) differential pressure of an inner interface, directional capillary driving differential pressure is generated, the rapid outflow of fluid is promoted, the fluid is broken under the Rayleigh instability effect to form liquid drops, the two effects are mutually cooperated, the generation power of emulsion is improved, and the generation of double emulsion can be promoted by serially connecting two stages of emulsification modules. 2. In the step type emulsification mode, the size of the liquid drop is mainly controlled by surface/interface tension and is insensitive to flow change, so that the uniformity of the size of the liquid drop generated by each emulsification unit is ensured to the maximum extent. 3. The fractal structure fluid distribution channel with multi-stage configuration realizes uniform distribution and transportation of fluid from a large-runoff main flow to a plurality of sub-channels, ensures monodispersity generated by droplets of each emulsifying unit, and can greatly reduce the number of injection pumps required in the process of mass production of droplets. 4. The generated double emulsion is cured into the microcapsule by adding an ultraviolet or heating curing device in the follow-up process, so that the application of the microcapsule in a plurality of fields such as medicines, chemical engineering and the like can be expanded.

Drawings

FIG. 1 is a schematic structural view of the present invention;

FIG. 2 is a schematic view of the internal structure of the channel plate;

FIG. 3 is a top view of the internal structure of the channel plate;

FIG. 4 is a schematic structural diagram of a first-stage emulsification unit and a second-stage emulsification unit;

FIG. 5 is a top view of a first stage emulsification unit;

FIG. 6 is a schematic view of a liquid supply base plate configuration;

FIG. 7 is a schematic diagram of double emulsion formation.

Wherein: 1-channel plate, 2-cover plate, 3-liquid supply bottom plate, 4-internal phase fluid, 5-intermediate phase fluid, 6-single droplet, 7-external phase fluid, 8-double emulsion, 11-internal phase fluid distribution module, 12-first-stage emulsification module, 13-second-stage emulsification module, 21-double emulsion delivery channel, 31-internal phase fluid supply channel, 32-intermediate phase fluid supply distribution module, 33-external phase fluid supply distribution module, 111-internal phase fluid main channel, 112-internal phase fluid sub-channel, 121-internal phase fluid delivery channel, 122-first-stage constant depth wedge-shaped flow cross section divergent structure, 123-first-stage variable depth longitudinal divergent step structure, 124-intermediate phase fluid delivery channel, 131-second-stage constant depth wedge-shaped flow cross section divergent structure, 132-two-stage variable depth longitudinal sudden expansion step structure, 133-outer phase fluid conveying channel, 321-intermediate phase fluid main channel, 322-intermediate phase fluid sub-channel, 323-intermediate phase fluid supply channel, 331-outer phase fluid main channel, 332-outer phase fluid sub-channel and 333-outer phase fluid supply channel.

Detailed Description

For the understanding of the present invention, the following detailed description will be given with reference to the accompanying drawings, which are provided for the purpose of illustration only and are not intended to limit the scope of the present invention.

Fig. 1 to 6 show an embodiment of a fractal stepped channel type double emulsion microfluidic mass production device, which includes a cover plate 2, a channel plate 1 and a liquid supply bottom plate 3, which are hermetically connected from top to bottom, wherein a double emulsion delivery channel 21 is disposed in the cover plate 2, an internal phase fluid distribution module 11, a first-stage emulsification module 12 and a second-stage emulsification module 13 are disposed in the channel plate 1, and an internal phase fluid liquid supply channel 31, an intermediate phase fluid liquid supply distribution module 32 and an external phase fluid supply distribution module 33 are disposed in the liquid supply bottom plate 3. The first-stage emulsification module 12 comprises a plurality of parallel first-stage emulsification units, each first-stage emulsification unit comprises an inner-phase fluid conveying channel 121, a first-stage constant-depth wedge-shaped flow section divergent structure 122, a first-stage variable-depth longitudinal sudden-expansion stepped structure 123 and an intermediate-phase fluid conveying channel 124, an outlet of the inner-phase fluid conveying channel 121 is connected with an inlet of the first-stage constant-depth wedge-shaped flow section divergent structure 122, an outlet of the first-stage constant-depth wedge-shaped flow section divergent structure 122 is connected with an inlet of the first-stage variable-depth longitudinal sudden-expansion stepped structure 123, the intermediate-phase fluid conveying channel 124 is communicated with the bottom of the first-stage variable-depth longitudinal sudden-expansion stepped structure 123, the second-stage emulsification module 13 comprises a plurality of parallel second-stage emulsification units, each second-stage emulsification unit comprises a second-stage constant-depth wedge-shape flow section divergent structure 131, a second-stage variable-depth longitudinal sudden-expansion stepped structure 132 and an outer-phase fluid conveying channel 133, the outlet of the first-stage variable-depth longitudinal sudden-expansion step structure 123 is connected with the inlet of the second-stage constant-depth wedge-shaped flow section divergent structure 131, the outlet of the second-stage constant-depth wedge-shaped flow section divergent structure 131 is connected with the inlet of the second-stage variable-depth longitudinal sudden-expansion step structure 132, the outer phase fluid conveying channel 133 is communicated with the bottom of the second-stage variable-depth longitudinal sudden-expansion step structure 132, the divergent angle beta range of the first-stage constant-depth wedge-shaped flow section divergent structure 122 and the second-stage constant-depth wedge-shaped flow section divergent structure 131 is 10-35 degrees, the depths of the first-stage variable-depth longitudinal sudden-expansion step structure 123 and the second-stage variable-depth longitudinal sudden-expansion step structure 132 are at least 2 times that of the first-stage constant-depth wedge-shaped flow section divergent structure 122 and the second-stage constant-depth wedge-shaped flow section divergent structure 131 respectively, and the double emulsion conveying channel 21 is connected with the outlet of the second-stage variable-depth longitudinal sudden-expansion step structure 132.

The inner phase fluid distribution module 11 comprises an inner phase fluid main channel 111 and an inner phase fluid sub-channel 112 which are communicated in sequence, wherein the inner phase fluid main channel 111 is branched to form two inner phase fluid sub-channels 112, each inner phase fluid sub-channel 112 is branched to form two inner phase fluid sub-channels 112 of the next stage until the tail end of the inner phase fluid distribution module 11 forms 2ⁿThe number of inner phase fluid sub-channels 112, n is the fractal progression of the inner phase fluid sub-channels 112, and is a natural number of the nth stage of the inner phase fluid sub-channels 112 and the inner phase fluid transport channels 121The inlets are communicated. Length l of i-1 th stage internal phase fluid sub-channel_i-1And the length l of the i-th stage internal phase fluid sub-channel_iSatisfyHydraulic radius d of i-1 stage internal phase fluid sub-channel_i-1And the hydraulic radius d of the i-th stage inner phase fluid sub-channel_iSatisfyWherein Δ is the length fractal dimension. The intermediate phase fluid supply and distribution module 32 comprises an intermediate phase fluid supply channel 323, an intermediate phase fluid main channel 321 and intermediate phase fluid sub-channels 322 which are connected in sequence, wherein the intermediate phase fluid main channel 321 is branched to form two intermediate phase fluid sub-channels 322, each intermediate phase fluid sub-channel 322 is branched to form two intermediate phase fluid sub-channels 322 of the next stage, and the two intermediate phase fluid sub-channels 2 are formed till the tail end of the intermediate phase fluid supply and distribution module 32^jThe number of the intermediate phase fluid sub-channels 322, j is the fractal series of the intermediate phase fluid sub-channels 322, the j-th stage of the intermediate phase fluid sub-channels 322 is connected with the inlet of the intermediate phase fluid conveying channel 124, the external phase fluid supply distribution module 33 comprises an external phase fluid supply channel 333, an external phase fluid main channel 331 and an external phase fluid sub-channel 332 which are connected in sequence, the external phase fluid main channel 331 is branched to form two external phase fluid sub-channels 332, each external phase fluid sub-channel 332 is branched to form two external phase fluid sub-channels 332 of the next stage until the tail end of the external phase fluid supply distribution module 33 forms 2^kThe number of the outer-phase fluid sub-channels 332, k is a fractal series of the outer-phase fluid sub-channels 332, and the k-th stage outer-phase fluid sub-channel 332 is connected to an inlet of the outer-phase fluid conveying channel 133, where j ═ k ═ n.

The specific working principle of the above embodiment is as follows:

as shown in FIG. 7, the internal phase fluid 4 flows from the internal phase fluid supply channel 31 into the internal phase fluid distribution module 11 having a fractal structure, and the intermediate phase fluid 5 is distributed by the intermediate phase fluid supply distribution module 32 to fill the intermediate phase fluid delivery channel 124 with a one-stage wedge-shaped flow cross section diverging structure 122 and a single-stage wedge-shaped flow cross section diverging structureThe stepped depth longitudinally abruptly expands the stepped structure 123. When the inner phase fluid 4 reaches the first-stage emulsification module 12, the first-stage constant-depth wedge-shaped flow cross section divergent structure 122 enables the front end of the inner interface between the inner phase fluid 4 and the intermediate phase fluid 5 to be separated from contact with the side wall of the channel, the interface generates centripetal contraction under the action of interface tension, the growth of inner phase fluid 4 droplets SE (single expansion) is promoted, and when the front end of the inner interface moves to the first-stage variable-depth longitudinal divergent stepped structure 123, the longitudinal divergent of the channel depth enables the front end of the inner interface to grow into a radius r_dWith an interface pressure of p_i1，

Wherein p is_o1The pressure of the intermediate phase fluid, and gamma is the interfacial tension coefficient of the water phase and the oil phase.

With the contraction of the neck, the neck pressure is p_n1，

Wherein alpha is the contact angle between the oil phase and the inner wall surface of the solid, h is the channel height, and r₁Is the radius of curvature in the x-y plane, r₂Is the radius of curvature in the y-z plane.

The pressure in the neck and the bulb-shaped head produce a capillary pressure difference Δ p ═ p_n1-p_i1Causing the neck to break off, creating a single drop 6.

The generated single liquid drop 6 continues to flow forwards in the channel along with the intermediate phase fluid 5, and after the outer phase fluid 7 is distributed by the outer phase fluid supply and distribution module 33, the two-stage constant-depth wedge-shaped flow section divergent structure 131 and the two-stage variable-depth longitudinal sudden-expansion stepped structure 132 are filled in the outer phase fluid conveying channel 133. When the intermediate phase fluid 5, which surrounds the single droplet 6, reaches the secondary emulsification module 13, the outer interface between the intermediate phase fluid 5 and the outer phase fluid 7 undergoes a similar process as the inner phase fluid 4, breaking to form a double emulsion 8.

The above embodiments are merely illustrative of the technical concept and structural features of the present invention, and are intended to be implemented by those skilled in the art, but the present invention is not limited thereto, and any equivalent changes or modifications made according to the spirit of the present invention should fall within the scope of the present invention.