Method for preparing single-solid-core solid-water-oil liquid drops based on liquid drop splitting

Abstract

The invention discloses a method for preparing single-solid-core solid-water oil droplets based on droplet splitting, which comprises the following steps: preparing a T-shaped through microchannel and Y-shaped microchannel composite micro-fluidic chip, inserting stainless steel capillary tubes into an inlet and an outlet of the composite micro-fluidic chip, and sealing by using AB glue; preparing a dispersed phase and a continuous phase; the method comprises the following steps: constructing a composite microfluidic platform, controlling the flow rates of a dispersed phase and a continuous phase by using an injection pump, continuously generating double-solid-core water-solid oil drops at a T-shaped microchannel, and splitting the double-solid-core water-solid oil drops into two single-solid-core water-solid oil drops at a Y-shaped microchannel. High-flux preparation of the single-solid-core water-fixing oil droplets is realized by adopting a composite channel of a T-shaped micro-channel and a Y-shaped micro-channel, the T-shaped micro-channel is used for preparing the double-solid-core water-fixing oil droplets, the Y-shaped micro-channel is used for splitting the double-solid-core water-fixing oil droplets, and two single-solid-core water-fixing oil droplets with uniform sizes are obtained after splitting.

Description

Technical Field

[0001] The present invention belongs to the field of microfluidic preparation of novel materials, and more specifically, relates to a method for preparing single solid-core solid-water-oil droplets based on droplet splitting. Background Art

[0002] Single solid core solid water oil droplets produced by microfluidic devices have wide applications in biochemistry, drug delivery, functional materials and inertial confinement fusion (ICF) experiments. In particular, in ICF implosion experiments, the most commonly used double-layer microspheres have single solid core solid water oil droplets as their precursor. Since the solid core precursor used in the implosion experiment is a high-precision polystyrene (PS) hollow microsphere with extremely strict requirements on sphericity, wall thickness uniformity and surface finish, it is of great significance to improve the utilization rate of high-precision hollow microspheres in the process of preparing single solid core solid water oil droplets.

[0003] The existing technology has been able to produce single solid-core solid-water-oil droplets through co-flow, cross-flow and flow focusing channels. However, in the process of preparing single solid-core solid-water-oil droplets using these methods, the generation of double solid-core solid-water-oil droplets is inevitable, which greatly reduces the utilization efficiency of high-precision hollow microspheres. At the same time, the preparation of single solid-core solid-water-oil droplets for thin liquid films requires a large continuous phase flow rate, which easily causes the solid-water-oil droplet system to become unstable, resulting in the separation of the hollow microspheres from the liquid film, i.e., the solid core is de-coated. The generation of double solid-core solid-water-oil droplets requires a smaller continuous phase flow rate. If the double solid-core solid-water-oil droplets can be evenly split, a stable thin liquid film single solid-core solid-water-oil droplet can be obtained. Therefore, how to achieve controllable splitting of double solid-core solid-water-oil droplets to single solid-core solid-water-oil droplets is the key to improving the utilization rate of high-precision hollow microspheres and the efficiency of ICF target sphere preparation. Summary of the invention

[0004] An object of the present invention is to solve at least the above problems and / or disadvantages and to provide at least the advantages which will be described hereinafter.

[0005] In order to achieve these objects and other advantages of the present invention, a method for preparing single solid-core solid-water-oil droplets based on droplet splitting is provided, comprising the following steps:

[0006] Step 1: Prepare a T-type microchannel + Y-type microchannel composite microfluidic chip, insert a stainless steel capillary into the inlet and outlet of the composite microfluidic chip, and seal it with AB glue;

[0007] Step 2: Use a dropper to draw high-precision polystyrene (PS) hollow microspheres soaked in ultrapure water into a beaker, and then drip polyvinyl alcohol (PVA) solution after the water is completely sucked out. After soaking for a period of time, use it as a dispersed phase, and then prepare an oil phase solution mixed with dibutyl phthalate (DBP) and dioctyl sebacate (DOS) as a continuous phase;

[0008] Step 3: Build a composite microfluidic platform, use a syringe pump to control the flow rate of the dispersed phase and the continuous phase, continuously generate double solid-core solid-water-oil droplets in the T-type microchannel, and split them into two single solid-core solid-water-oil droplets in the Y-type microchannel.

[0009] Preferably, in the step 1, the inlet of the composite microfluidic chip includes a dispersed phase channel inlet and a continuous phase channel inlet, the channel of the microfluidic chip is square, the channel side length is 1 mm, and the relationship between the channel side length and the diameter of the PS hollow microsphere is: PS hollow microsphere diameter + 100 μm ≤ channel side length ≤ 2 times the PS hollow microsphere diameter, the inner diameter of the stainless steel capillary ≥ PS hollow microsphere diameter + 100 μm, and the outer diameter of the stainless steel capillary < channel side length.

[0010] Preferably, in step 1, the T-shaped microchannel can be replaced by a cross channel or a Y-shaped microchannel, and the angle of the Y-shaped microchannel is 10° to 180°.

[0011] Preferably, in the step 1, when preparing the T-shaped microchannel + Y-shaped microchannel composite microfluidic chip, a serpentine microchannel is added between the T-shaped microchannel and the Y-shaped microchannel.

[0012] Preferably, in the step 2, the diameter of the high-precision polystyrene (PS) hollow microspheres is 750±5 μm.

[0013] Preferably, in the step 2, the concentration of the polyvinyl alcohol (PVA) solution is 2 wt %, the molecular weight of the polyvinyl alcohol (PVA) is 13,000 to 23,000, and the degree of hydrolysis is 87 to 89%.

[0014] Preferably, in the step 2, the volume ratio of dibutyl phthalate (DBP) to dioctyl sebacate (DOS) is 140-150:60-70.

[0015] Preferably, in the step three, the specific method of building the composite microfluidic platform is: take a glass capillary, burn one end of the glass capillary with an alcohol burner so that its inner diameter is smaller than the diameter of the PS hollow microspheres to produce a limiting effect, insert the burned end into the PTFE hose, and suck the PS hollow microspheres dispersed in the PVA solution into the glass capillary, and then use another section of PTFE hose to connect the unburned end of the glass capillary to the stainless steel capillary at the entrance of the dispersed phase channel, and then use another section of PTFE hose to connect the oil phase solution to the stainless steel capillary at the entrance of the continuous phase channel; then connect the unconnected ends of all PTFE hoses to different injection pumps respectively.

[0016] Preferably, in step three, the flow rate ratio of the dispersed phase to the continuous phase is 0.89 to 1.6:1.

[0017] Preferably, in step three, when building the composite microfluidic platform, the glass capillary can be replaced by a stainless steel capillary, the alcohol burner burning limit can be replaced by a mechanical flattening limit, the outer diameter of the glass capillary is consistent with that of the stainless steel capillary, and the inner diameter does not exceed that of the stainless steel capillary.

[0018] The present invention has at least the following beneficial effects:

[0019] (1) The present invention adopts a T-shaped microchannel to obtain double solid-core solid-water-oil droplets, thereby avoiding the problem of mixing double solid-core solid-water-oil droplets in the process of directly generating single solid-core solid-water-oil droplets, improving the utilization efficiency of high-precision solid cores, and simultaneously generating a small continuous phase flow rate of double solid-core solid-water-oil droplets, thereby ensuring the stability of subsequent droplets and making the collected single solid-core solid-water-oil droplets less likely to be de-coated.

[0020] (2) The present invention can control the size of the generated dual solid-core solid-water-oil droplets within a certain range by adjusting the flow rate of each phase, thereby controlling the size of the single solid-core solid-water-oil droplets after splitting at the Y-shaped microchannel, and the obtained single solid-core solid-water-oil droplets have uniform size and good monodispersity; and a serpentine microchannel is added between the T-shaped microchannel and the Y-shaped microchannel to stabilize the droplet shape.

[0021] (3) The composite microfluidic chip of the present invention is reusable, simple to operate, and easy to mass produce.

[0022] Other advantages, objectives and features of the present invention will be embodied in part through the following description, and in part will be understood by those skilled in the art through study and practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 The figure is a physical picture of the composite microfluidic chip of the present invention and a local high-speed photograph;

[0024] Figure 2 Schematic diagram of the microfluidic chip of the present invention;

[0025] Figure 3 This is a diagram showing the size distribution of a single solid core solid water oil droplet in Example 1 of the present invention;

[0026] Figure 4 This is a diagram showing the size distribution of a single solid core solid water oil droplet in Example 2 of the present invention;

[0027] Figure 5 This is the single solid core solid water oil droplet size distribution diagram in Example 3 of the present invention. DETAILED DESCRIPTION

[0028] The present invention is further described in detail below in conjunction with the accompanying drawings so that those skilled in the art can implement the invention with reference to the description.

[0029] Example 1

[0030] A method for preparing single solid-core solid-water-oil droplets based on droplet splitting, comprising the following steps:

[0031] Step 1: Prepare a T-type microchannel + serpentine microchannel + Y-type microchannel composite microfluidic chip using a CNC machine tool, wherein the channel side length is 1 mm and the Y-type microchannel angle is 30°. Insert a stainless steel capillary into the dispersed phase inlet, continuous phase inlet and outlet of the composite microfluidic chip and seal them with AB glue;

[0032] Step 2: Prepare a 2%wt PVA aqueous solution (molecular weight 13000, degree of hydrolysis 87%), use a dropper to draw PS hollow microspheres (diameter 750±5μm) soaked in ultrapure water into a beaker, absorb the water and then drip into the PVA solution, soak for a period of time and use it as a dispersed phase, then use a mixed oil phase solution of 144mL DBP and 66mL DOS as a continuous phase;

[0033] Step 3: Take a glass capillary and burn one end of the glass capillary with an alcohol burner to make its inner diameter smaller than the diameter of the PS hollow microspheres to produce a limiting effect. Insert the burned end into the PTFE hose and suck 50 PS hollow microspheres dispersed in the PVA solution into the glass capillary. Then use another section of PTFE hose to connect the unburned end of the glass capillary to the stainless steel capillary at the entrance of the dispersed phase channel, and then use another section of PTFE hose to connect the oil phase solution to the stainless steel capillary at the entrance of the continuous phase channel; then connect the unconnected ends of all PTFE hoses to different injection pumps. The dispersed phase flow rate was controlled at 10 mL / h and the continuous phase flow rate was 10 mL / h by using a syringe pump. Double solid-core solid-water-oil droplets were continuously generated at the T-type microchannel and split into two single solid-core solid-water-oil droplets at the Y-type microchannel. The size of the single solid-core solid-water-oil droplets obtained after splitting was distributed in the range of 1135 to 1365 μm, with an average size of 1249.9 μm and a coefficient of variation of 3.30%.

[0034] Example 2

[0035] A method for preparing single solid-core solid-water-oil droplets based on droplet splitting, comprising the following steps:

[0036] Step 1: Prepare a T-type microchannel + serpentine microchannel + Y-type microchannel composite microfluidic chip using a CNC machine tool, wherein the channel side length is 1 mm and the Y-type microchannel angle is 60°. Insert a stainless steel capillary into the dispersed phase inlet, continuous phase inlet and outlet of the composite microfluidic chip and seal them with AB glue;

[0037] Step 2: Prepare a 2%wt PVA aqueous solution (molecular weight 18000, degree of hydrolysis 88%), use a dropper to draw PS hollow microspheres (diameter 750±5μm) soaked in ultrapure water into a beaker, absorb the water and then drip into the PVA solution, soak for a period of time and use it as a dispersed phase, then use a mixed oil phase solution of 144mL DBP and 66mL DOS as a continuous phase;

[0038] Step 3: Take a glass capillary and burn one end of the glass capillary with an alcohol burner to make its inner diameter smaller than the diameter of the PS hollow microspheres to produce a limiting effect. Insert the burned end into the PTFE hose and suck 50 PS hollow microspheres dispersed in the PVA solution into the glass capillary. Then use another section of PTFE hose to connect the unburned end of the glass capillary to the stainless steel capillary at the entrance of the dispersed phase channel, and then use another section of PTFE hose to connect the oil phase solution to the stainless steel capillary at the entrance of the continuous phase channel; then connect the unconnected ends of all PTFE hoses to different injection pumps. The dispersed phase flow rate was controlled at 20 mL / h and the continuous phase flow rate was 20 mL / h by using an injection pump. Double solid-core solid-water-oil droplets were continuously generated at the T-type microchannel and split into two single solid-core solid-water-oil droplets at the Y-type microchannel. The size of the single solid-core solid-water-oil droplets obtained after splitting was distributed in the range of 1130 to 1270 μm, with an average size of 1188.5 μm and a coefficient of variation of 2.97%.

[0039] Example 3

[0040] A method for preparing single solid-core solid-water-oil droplets based on droplet splitting, comprising the following steps:

[0041] Step 1: Prepare a T-type microchannel + serpentine microchannel + Y-type microchannel composite microfluidic chip using a CNC machine tool, wherein the channel side length is 1 mm and the Y-type microchannel angle is 90°. Insert a stainless steel capillary into the dispersed phase inlet, continuous phase inlet and outlet of the composite microfluidic chip and seal them with AB glue;

[0042] Step 2: Prepare a 2%wt PVA aqueous solution (molecular weight 23000, degree of hydrolysis 89%), use a dropper to draw PS hollow microspheres (diameter 750±5μm) soaked in ultrapure water into a beaker, absorb the water and then drip into the PVA solution, soak for a period of time and use it as a dispersed phase, then use a mixed oil phase solution of 144mL DBP and 66mL DOS as a continuous phase;

[0043] Step 3: Take a glass capillary and burn one end of the glass capillary with an alcohol burner to make its inner diameter smaller than the diameter of the PS hollow microspheres to produce a limiting effect. Insert the burned end into the PTFE hose and suck 50 PS hollow microspheres dispersed in the PVA solution into the glass capillary. Then use another section of PTFE hose to connect the unburned end of the glass capillary to the stainless steel capillary at the entrance of the dispersed phase channel, and then use another section of PTFE hose to connect the oil phase solution to the stainless steel capillary at the entrance of the continuous phase channel; then connect the unconnected ends of all PTFE hoses to different injection pumps. The dispersed phase flow rate was controlled at 30 mL / h and the continuous phase flow rate was 30 mL / h by using an injection pump. Double solid-core solid-water-oil droplets were continuously generated at the T-type microchannel and split into two single solid-core solid-water-oil droplets at the Y-type microchannel. The size of the single solid-core solid-water-oil droplets obtained after splitting was distributed in the range of 1080 to 1240 μm, with an average size of 1149.7 μm and a coefficient of variation of 3.49%.

[0044] Comparative Example 1

[0045] A method for preparing monodisperse solid-water-oil composite emulsion particles comprises the following steps:

[0046] Step 1: Prepare PS hollow microspheres with a diameter of 750±5 μm, i.e., solid core, using a coaxial emulsion generator;

[0047] Step 2: Prepare a cross-flow focusing microfluidic device with a vertical main channel and a horizontal side channel having a diameter of 1 mm by using a casting method;

[0048] Step 3: Prepare a PVA solution with a molecular weight of 13,000, a hydrolysis degree of 87%, and a mass concentration of 2% according to the density matching range requirements; mix 144 mL of DBP and 66 mL of DOS as an oil phase solution;

[0049] Step 4: Use the aqueous PVA solution to absorb 50 PS hollow microspheres containing internal phase water into the capillary; and tightly connect the capillary to the vertical main channel of the cross flow focusing microfluidic device, and at the same time, use a hose to tightly connect the oil phase solution to the horizontal side channels on both sides of the cross flow focusing microfluidic device;

[0050] Step 5: Use a syringe pump to control the flow rate of the vertical main channel and the horizontal side channels on both sides, adjust the volume flow rate of the vertical main channel to 20mL / h, and the volume flow rate of the horizontal side channel to 20mL / h; form a dispersed phase in the vertical main channel, and form a continuous phase in the horizontal side channels on both sides; when the dispersed phase and the continuous phase meet at the cross of the cross flow focusing microfluidic device, the dispersed phase is sheared by the continuous phase to form a solid-water-oil composite emulsion; after the solid-water-oil composite emulsion is formed, it is transported through the straight pipe at the lower end of the cross flow focusing microfluidic device to obtain a solid-water-oil composite emulsion, that is, a single solid-core solid-water-oil droplet.

[0051] The results of geometric size test show that the size of the obtained single solid core solid water-oil droplets is distributed between 840 and 885 μm, with a coefficient of variation of 5%.

[0052] Comparative Example 2

[0053] A method for preparing monodisperse solid-water-oil composite emulsion particles comprises the following steps:

[0054] Step 1: Prepare PS hollow microspheres with a diameter of 800±5 μm, i.e., solid core, using a coaxial emulsion generator;

[0055] Step 2: Prepare a cross-flow focusing microfluidic device with a vertical main channel and a horizontal side channel having a diameter of 1 mm by using a casting method;

[0056] Step 3: Prepare a PVA solution with a molecular weight of 13,000, a hydrolysis degree of 87%, and a mass concentration of 2% according to the density matching range requirements; mix 140 mL of DBP and 70 mL of DOS as an oil phase solution;

[0057] Step 4: Use the aqueous PVA solution to absorb 50 polystyrene hollow microspheres containing internal phase water into the capillary; and tightly connect the capillary to the vertical main channel of the cross flow focusing microfluidic device, and at the same time, use a hose to tightly connect the oil phase solution to the horizontal side channels on both sides of the cross flow focusing microfluidic device;

[0058] Step 5: Use a syringe pump to control the flow rate of the vertical main channel and the horizontal side channels on both sides, adjust the volume flow rate of the vertical main channel to 40mL / h, and the volume flow rate of the horizontal side channel to 40mL / h; form a dispersed phase in the vertical main channel, and form a continuous phase in the horizontal side channels on both sides; when the dispersed phase and the continuous phase meet at the cross of the cross flow focusing microfluidic device, the dispersed phase is sheared by the continuous phase to form a solid-water-oil composite emulsion; after the solid-water-oil composite emulsion is formed, it is transported through the straight pipe at the lower end of the cross flow focusing microfluidic device to obtain a solid-water-oil composite emulsion, that is, a single solid-core solid-water-oil droplet.

[0059] The geometric size test results show that the size of the obtained single solid core solid water oil droplet is distributed between 880 and 925 μm, with a coefficient of variation of 7%;

[0060] Comparative Example 3:

[0061] A method for preparing monodisperse solid-water-oil composite emulsion particles comprises the following steps:

[0062] Step 1: Prepare PS hollow microspheres with a diameter of 850±5 μm, i.e., solid core, using a coaxial emulsion generator;

[0063] Step 2: Prepare a cross-flow focusing microfluidic device with a vertical main channel and a horizontal side channel having a diameter of 1 mm by using a casting method;

[0064] Step 3: Prepare a PVA solution with a molecular weight of 15,000, a hydrolysis degree of 90%, and a mass concentration of 3% according to the density matching range requirements; mix 140 mL of DBP, 70 mL of DOS, and 70 mL of dioctyl phthalate (DOP) as an oil phase solution;

[0065] Step 4: Use the aqueous PVA solution to absorb 50 polystyrene hollow microspheres containing internal phase water into the capillary; and tightly connect the capillary to the vertical main channel of the cross flow focusing microfluidic device, and at the same time, use a hose to tightly connect the oil phase solution to the horizontal side channels on both sides of the cross flow focusing microfluidic device; the inner diameter of the capillary is consistent with the inner diameter of the vertical main channel of the cross flow focusing microfluidic device;

[0066] Step 5: Use a syringe pump to control the flow rate of the vertical main channel and the horizontal side channels on both sides, adjust the volume flow rate of the vertical main channel to 30mL / h, and the volume flow rate of the horizontal side channel to 30mL / h; form a dispersed phase in the vertical main channel, and form a continuous phase in the horizontal side channels on both sides; when the dispersed phase and the continuous phase meet at the cross of the cross flow focusing microfluidic device, the dispersed phase is sheared by the continuous phase to form a solid-water-oil composite emulsion; after the solid-water-oil composite emulsion is formed, it is transported through the straight pipe at the lower end of the cross flow focusing microfluidic device to obtain a solid-water-oil composite emulsion, that is, a single solid-core solid-water-oil droplet.

[0067] The results of geometric size test show that the size of the obtained single solid core solid water-oil droplets is distributed in the range of 945-995 μm, with a coefficient of variation of 8%.

[0068] Comparative Examples 1-3 all use a cross shearing method to generate single-core solid-water-oil composite emulsions, and their coefficients of variation are relatively high, 5%, 7% and 8% respectively, indicating that Comparative Examples 1-3 cannot stably generate solid-water-oil droplets. The present invention uses a T-type channel to stably generate dual-solid-core solid-water-oil droplets, and then uses a Y-type channel to split and prepare single-core solid-water-oil droplets. The coefficients of variation in the three embodiments are 3.30%, 2.97% and 3.49% respectively, which are better than the comparative examples, and can avoid the problem of generating dual-core droplets when directly generating single-core solid-water-oil droplets.

[0069] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and the implementation modes, and they can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A method for preparing single solid-core solid-water-oil droplets based on droplet splitting, characterized in that: The following steps are involved: Step 1: Prepare a T-type microchannel + Y-type microchannel composite microfluidic chip, insert a stainless steel capillary into the inlet and outlet of the composite microfluidic chip, and seal it with AB glue; Step 2: Use a dropper to draw high-precision polystyrene hollow microspheres soaked in ultrapure water into a beaker, and then drip polyvinyl alcohol solution after the water is completely sucked out. After soaking for a period of time, use it as a dispersed phase, and then prepare an oil phase solution mixed with dibutyl phthalate and dioctyl sebacate as a continuous phase; Step 3: Build a composite microfluidic platform, use a syringe pump to control the flow rate of the dispersed phase and the continuous phase, continuously generate double solid-core solid-water-oil droplets in the T-type microchannel, and split them into two single solid-core solid-water-oil droplets in the Y-type microchannel.

2. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step 1, the inlet of the composite microfluidic chip includes a dispersed phase channel inlet and a continuous phase channel inlet. The channel of the microfluidic chip is square, the channel side length is 1 mm, and the relationship between the channel side length and the diameter of the PS hollow microsphere is: PS hollow microsphere diameter + 100 μm ≤ channel side length ≤ 2 times the PS hollow microsphere diameter, the inner diameter of the stainless steel capillary ≥ PS hollow microsphere diameter + 100 μm, and the outer diameter of the stainless steel capillary < channel side length.

3. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step 1, the T-shaped microchannel can be replaced by a cross channel or a Y-shaped microchannel, and the angle of the Y-shaped microchannel is 10° to 180°.

4. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step 1, when preparing the T-shaped microchannel + Y-shaped microchannel composite microfluidic chip, a serpentine microchannel is added between the T-shaped microchannel and the Y-shaped microchannel.

5. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step 2, the diameter of the high-precision polystyrene hollow microspheres is 750±5 μm.

6. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step 2, the concentration of the polyvinyl alcohol solution is 2 wt %, the molecular weight of the polyvinyl alcohol is 13,000 to 23,000, and the degree of hydrolysis is 87 to 89%.

7. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step 2, the volume ratio of dibutyl phthalate to dioctyl sebacate is 140-150:60-70.

8. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step three, the specific method for building the composite microfluidic platform is as follows: take a glass capillary, burn one end of the glass capillary with an alcohol burner so that its inner diameter is smaller than the diameter of the PS hollow microspheres to produce a limiting effect, insert the burned end into a PTFE hose, and suck the PS hollow microspheres dispersed in the PVA solution into the glass capillary, and then use another section of PTFE hose to connect the unburned end of the glass capillary to the stainless steel capillary at the entrance of the dispersed phase channel, and then use another section of PTFE hose to connect the oil phase solution to the stainless steel capillary at the entrance of the continuous phase channel; and then connect the unconnected ends of all PTFE hoses to different injection pumps.

9. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 1, characterized in that: In the step 3, the ratio of the dispersed phase to the continuous phase flow rate is 0.89 to 1.6:

1.

10. The method for preparing single solid-core solid-water-oil droplets based on droplet fission according to claim 8, characterized in that: In the step three, when building the composite microfluidic platform, the glass capillary can be replaced by a stainless steel capillary, the alcohol burner burning limit can be replaced by a mechanical flattening limit, the outer diameter of the glass capillary is consistent with that of the stainless steel capillary, and the inner diameter does not exceed that of the stainless steel capillary.

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