A microreactor and a method for preparing nanoparticles

Abstract

The present invention relates to a microreactor and a method for preparing nanoparticles, comprising a main channel and at least two flow channels connected in sequence, each flow channel being connected in series; the cross section of the flow channel is rectangular, a first side wall of the flow channel is provided with a first semi-elliptical cylindrical protrusion connected to the flow channel, a first semi-elliptical cylindrical diverter is provided in the flow channel; a second side wall is provided with a second semi-elliptical cylindrical protrusion connected to the flow channel; a fourth side wall is provided with a third semi-elliptical cylindrical protrusion connected to the flow channel; the second and third protrusions are symmetrically distributed along the length of the flow channel; a fourth semi-elliptical cylindrical protrusion connected to the flow channel is provided on the third side wall, and a second semi-elliptical cylindrical diverter is provided in the flow channel. The present invention maximizes the reaction intensity of the homogeneous microreactor by introducing a three-dimensional secondary flow structure, while minimizing the distance required for the reaction.

Description

Technical Field

[0001] The present invention relates to a microreactor and a method for preparing nanoparticles, in particular to a high-reaction-intensity homogeneous microreactor with a three-dimensional secondary flow structure and a method for preparing nanoparticles. Background Art

[0002] Thanks to their large surface-to-volume ratio, flexible fluid control, and micro-escalated reagent consumption, microreactors have been applied to microfluidic systems and have been widely used in fields such as fine chemical production, environmental monitoring, drug preparation, and biochemical sensing. Homogeneous reactors based on micromixing technology can evenly mix or dissolve reactants into a single gas or liquid phase. With the differences in micromixing structure design and fluid Reynolds number conditions, the heat and mass transfer laws such as chaotic convection, laminar flow, and diffusion in microscale fluids vary greatly during the microreaction process. Most studies have only focused on the micromixing index and not the reaction intensity. How to improve the mixing index while using shorter mixing distances and mixing times will be important parameters that determine the intensity of microreactions.

[0003] At present, there are two main ways to mix the reagents in the microchannel. Among them, active mixing usually promotes mixing by the input of external energy. Chinese invention patent application specification CN202211151097.7 discloses a proportional liquid mixer, in which several electric vibrators are installed and an ultrasonic generator is provided. Although it can precisely adjust the ratio of the mixed liquid and improve the mixing effect, it does not take into account the impact that external stimuli may have on the reactants, especially biological reactants. Passive mixing usually uses baffle structures, multi-layer mixing structures and splitting and recombination. Chinese invention patent application specification CN202111444407.X discloses a micro mixer. The microstructure includes a vertical baffle and two arc baffles to form an inverted Y shape, so that the fluid is divided when it contacts the vertical baffles of the microstructure. The arc baffle disturbs the laminar flow divided in front and refluxes. By setting multiple mixing chambers, the fluid undergoes multiple diversion and merging cycles, better disrupting the laminar flow to form a mixed flow, generating enough turbulence to quickly achieve complete mixing. It designs multiple baffle structures in the mixing chamber. The micro mixer is complex to process and has many obstacles in the tube, resulting in a high pressure drop. It only emphasizes the mixing efficiency (generally refers to the completeness of the mixing between different substances) but does not pay attention to the mixing intensity (generally refers to the intensity of the mixing between different substances. Generally, the shorter the mixing time and / or mixing distance, the higher the mixing intensity). Summary of the Invention

[0004] In view of the shortcomings of the prior art, one of the objects of the present invention is to provide a microreactor to maximize the mixing intensity within a shorter distance; a second object of the present invention is to provide a method for preparing nanoparticles using the above-mentioned microreactor.

[0005] In order to solve the above technical problems, the technical solutions of the present invention are as follows:

[0006] A microreactor comprises a main channel and at least two flow channels which are connected in sequence, wherein the flow channels are connected in series in sequence;

[0007] The cross section of the flow channel is rectangular, and the flow channel has a first side wall, a second side wall, a third side wall and a fourth side wall, and the first side wall, the second side wall, the third side wall and the fourth side wall are adjacent to each other in sequence to form the flow channel;

[0008] A first convex portion in the shape of a semi-elliptical cylinder is provided on the first side wall and is in communication with the flow channel. The length direction of the first convex portion is perpendicular to the length direction of the flow channel and parallel to the first side wall. A first diverter portion in the shape of a semi-elliptical cylinder is provided in the flow channel. The first diverter portion protrudes toward the direction where the first convex portion is located. Gaps are left between the first diverter portion and the first side wall, and between the first diverter portion and the third side wall. The length direction of the first diverter portion is parallel to the length direction of the first convex portion. The central axis of the first convex portion and the central axis of the first diverter portion are located in the same plane, and the plane is perpendicular to the length direction of the flow channel.

[0009] The second side wall is provided with a second protrusion in a semi-elliptical shape that is in communication with the flow channel, wherein the length direction of the second protrusion is mutually perpendicular to the length direction of the flow channel and is parallel to the second side wall; the fourth side wall is provided with a third protrusion in a semi-elliptical shape that is in communication with the flow channel, wherein the length direction of the third protrusion is mutually perpendicular to the length direction of the flow channel and is parallel to the fourth side wall; the second protrusion and the third protrusion are symmetrically distributed along the length direction of the flow channel;

[0010] The third side wall is provided with a fourth protrusion in a semi-elliptical shape that is connected to the flow channel, the length direction of the fourth protrusion is perpendicular to the length direction of the flow channel and parallel to the third side wall, a second diverter in a semi-elliptical shape is provided in the flow channel, the second diverter protrudes toward the direction of the fourth protrusion, a gap is left between the second diverter and the first side wall, and between the second diverter and the third side wall, the length direction of the second diverter is parallel to the length direction of the fourth protrusion, the central axis of the fourth protrusion and the central axis of the second diverter are located in the same plane, and the plane is perpendicular to the length direction of the flow channel;

[0011] Viewed along the length direction of the flow channel, oppositely arranged second and third protrusions are provided between adjacent first and fourth protrusions, and a first or fourth protrusion is provided between two adjacent second protrusions.

[0012] The present invention can generate secondary flows in four directions within a short distance in the microreactor through the reasonable arrangement and selection of the structures such as the protrusion and the diversion part, thereby achieving high mixing intensity in a large Re range, achieving complete mixing of the fluids in a short time, and having a short complete mixing distance L. mix and complete mixing time τ mix .

[0013] Furthermore, the angle between two adjacent flow channels is 60-120°, preferably 80-110°, and more preferably 90°. In this way, a zigzag structure is formed, which helps to further enhance the mixing intensity.

[0014] Furthermore, the length of each flow channel is 1.8 mm to 2.2 mm.

[0015] Furthermore, the axis parallel to the length direction of the flow channel is taken as the semi-major axis of the ellipse, and the axis perpendicular to the length direction of the flow channel is taken as the semi-minor axis of the ellipse. The semi-major axis a1 of the first protrusion and the fourth protrusion is 0.05-0.25 mm, and the semi-minor axis b1 is 0.05-0.5 mm. The distance W between the central axis of the first protrusion and the central axis of the fourth protrusion in the length direction of the corresponding flow channel is 0.6-1.25 mm; further, the semi-major axis a2 of the diverter is 0.05-0.25 mm, and the semi-minor axis b2 is 0.05-0.3 mm; further, the semi-major axis a3 of the second protrusion and the third protrusion is 0.08-0.12 mm, and the semi-minor axis b3 is 0.05-0.3 mm.

[0016] Furthermore, viewed along the length direction of the flow channel, a first protrusion, a second protrusion, a fourth protrusion and a second protrusion are sequentially provided on the flow channel.

[0017] Furthermore, it includes at least two inlet channels, one end of each inlet channel is connected to the main channel.

[0018] Furthermore, the length of the main channel is 0.1 mm to 0.3 mm.

[0019] Furthermore, it also includes an outlet channel, the inlet end of the outlet channel is connected to the outlet end of the last flow channel.

[0020] Furthermore, the length of the outlet channel is 1.5 mm to 2.1 mm.

[0021] Furthermore, the apparatus further comprises an amplification unit and a plurality of capillary channels and a color development well equal in number to the number of capillary channels. The amplification unit comprises a straight channel sharing a central axis with the main channel, the inlet of the straight channel being connected to the outlet of the last flow channel, the outlet of the straight channel being provided with a separator, the separator dividing the outlet into two symmetrically distributed sub-outlets, each of the two sub-outlets being connected to an arc segment, the outlet of each arc segment being connected to an amplification channel, the two amplification channels being symmetrically distributed along the central axis of the straight channel, one end of the plurality of capillary channels being connected to the amplification channel, and the other end of the plurality of capillary channels being connected to a color development well; the connection positions of the capillary channels on the amplification channel being symmetrically distributed along the central axis of the amplification unit. In this way, the flow pattern at the outlet of the last flow channel can be magnified and displayed, and the mixing state can be conveniently observed through each capillary channel and / or the color development well.

[0022] Furthermore, the angle between the amplification channel and the straight section is less than 90°, and furthermore is 10-85°.

[0023] Furthermore, the cross section of the amplification channel is rectangular, with a width of 0.5-1.2 mm, further 0.6-1 mm; a depth of 0.1-0.4 mm, further 0.2-0.3 mm;

[0024] Preferably, the number of the capillary channels is 15-25, further 17-21; more preferably, the cross-section of the capillary channel is rectangular, with a width of 0.05-2 mm and a depth of 0.05-0.2 mm;

[0025] Preferably, the capillary channel includes a first capillary segment and a second capillary segment connected in sequence, the first capillary segment is connected to the amplification unit, and the second capillary segment is connected to a color development hole, the first capillary segments are parallel to each other, and the distance between adjacent first capillary segments is 0.2-0.45 mm;

[0026] Preferably, the color development hole is cylindrical with a radius of 0.3-0.7 mm; preferably, the center distance between adjacent color development holes is 0.65-1.45 mm.

[0027] In this way, the amplification unit can make it easier for the fluid to enter the capillary channel, and further cooperate with numerous capillary channels to amplify the laminar flow at the outlet end of the last flow channel, so that the laminar flow can be visualized within a certain range, thereby achieving a smooth amplification of the flow state; the setting of the color development hole can make the color distribution of the laminar flow more obvious here, which is more suitable for image analysis and convenient for judging the degree of mixing.

[0028] Furthermore, the device further comprises a liquid reservoir, a trigger valve, and a trigger channel. The liquid reservoir, trigger valve, and main channel are sequentially connected, and the trigger channel is connected to the main channel. Thus, the liquid reservoir can be used to store samples to be tested and color-developing solution in advance, and the trigger valve can be used to simultaneously allow liquid from both liquid reservoirs to enter the main channel when driven by capillary force. The trigger channel can be used to trigger the activation of liquid from both liquid reservoirs.

[0029] Preferably, the area of the liquid reservoir is 3-6 mm 2 , depth of 0.2-0.4mm;

[0030] Preferably, the area of the trigger valve is 0.2-0.4 mm 2 , depth of 0.05-0.15mm;

[0031] Preferably, the trigger channel has a width of 0.05-0.2 mm and a depth of 0.2-0.4 mm.

[0032] Furthermore, the number of flow channels is multiple, and can be selected as 3-10, further selected as 4-8, and further selected as 5-7.

[0033] The method for preparing nanoparticles using the microreactor as described above comprises the following steps:

[0034] (1) The raw material solution is fed into the main channel, and the reaction solution is collected at the outlet of the last flow channel;

[0035] (2) The reaction solution is subjected to solid-liquid separation to obtain a precipitated substrate, which is then dried to obtain nanoparticles.

[0036] Optionally, the raw material solution includes a first raw material solution and a second raw material solution. Optionally, the first raw material solution is a zinc acetate solution with a concentration of 8-12 mM; the second raw material solution is a 2-methylimidazole solution with a concentration of 35-45 mM.

[0037] Optionally, the raw material liquid is fed into the main channel through the inlet channel. Preferably, the Reynolds number Re of the raw material liquid fed into the two inlet channels is 50-1200.

[0038] Optionally, in step (2), the reaction solution is centrifuged to obtain a precipitated substrate. Preferably, the centrifugation time is 1-2 hours.

[0039] Optionally, in step (2), the product is dried at a constant temperature in a constant temperature box.

[0040] The present invention exhibits excellent mixing performance and high reaction intensity at relatively mild heat, with low requirements for microreactor preparation, materials, and liquid pumping. It can produce nanoparticles with high yield, adjustable particle size, and strong drug-loading capacity at mild heat, while also significantly promoting diffusion reactions. Its promotion of enzyme-catalyzed reactions at low heat can effectively avoid false negatives, providing a new sensing method for immunoassays and potential applications in point-of-care (POCT) applications.

[0041] Compared with the prior art, the present invention has the following beneficial effects:

[0042] (1) The microreactor of the present invention has high reaction intensity, short mixing time and short mixing distance. By introducing a three-dimensional secondary flow structure, the reaction intensity of the homogeneous microreactor is maximized, while the distance required for the reaction is shortened as much as possible. Compared with microreactors with more baffle structures and split-recombination types, the microreactor of the present invention has a lower pressure drop, milder reaction conditions, and higher microscopic reaction intensity under a wider range of Reynolds number conditions.

[0043] (2) The method for preparing nanoparticles provided by the present invention can produce nanoparticles with uniform morphology and adjustable particle size under relatively mild Reynolds number conditions, while having a high yield. This provides a reliable method for preparing high-performance drug-loaded nanoparticles.

[0044] (3) The microreactor of the present invention can be used in immunoassays to rapidly detect trace concentrations of analytes. The high-reaction-intensity homogeneous microreactor can enhance the reaction between the analyte and the chromogenic agent, thus avoiding false negatives. BRIEF DESCRIPTION OF THE DRAWINGS

[0045] Figure 1 Schematic diagram of the structure of the microreactor of Example 1.

[0046] Figure 2 Schematic diagram of the channel structure of Example 1.

[0047] Figure 3 Schematic diagram of the flow channel structure of Example 1, wherein the upper figure is a view along the direction perpendicular to the second side wall, and the lower figure is a view along the direction perpendicular to the third side wall.

[0048] Figure 4 This is a diagram of the mixing effect under different semi-minor axis b1 conditions.

[0049] Figure 5 This is a diagram of the mixing effect under different center distance W conditions.

[0050] Figure 6 This is a diagram of the mixing effect under different semi-major axis a2 conditions.

[0051] Figure 7 This is a diagram of the mixing effect under different semi-minor axis b2 conditions.

[0052] Figure 8 This is a graph showing the effect of the shape of the splitter on the mixing efficiency.

[0053] Figure 9 Graph showing the mixing effect under different semi-minor axis b3 conditions.

[0054] Figure 10 A comparison chart of the mixing efficiency of four microreactors with different structures under a wide range of Reynolds numbers.

[0055] Figure 11 Schematic diagram of the process for preparing ZIF-8 nanoparticles in Example 3.

[0056] Figure 12 This is the infrared spectrum of the ZIF-8 product prepared in Example 3 and sodium fluorescein.

[0057] Figure 13 These are scanning electron microscope images of the pure ZIF-8 prepared in Example 3. The left image is a SEM image at a Reynolds number of 100, and the right image is a SEM image at a Reynolds number of 500.

[0058] Figure 14 The absorbance graphs of the supernatants obtained by preparing ZIF-8 products using three microreactors.

[0059] Figure 15 The fluorescence intensity graphs of the supernatant obtained by preparing ZIF-8 products using three microreactors.

[0060] Figure 16 Schematic diagram of diffusion reaction detection at low Reynolds number using two methods in Example 4.

[0061] Figure 17 This is a schematic diagram of the structure of a microreactor for carrying out diffusion reaction using a syringe pump as in Example 4.

[0062] Figure 18 This is a schematic diagram of the structure of a microreactor using a capillary pump to carry out diffusion reaction in Example 5.

[0063] Figure 19 This is the fluorescence intensity distribution diagram at the capillary channel of Example 4.

[0064] Figure 20 4 is a linear fitting graph of the absolute value of the fitting slope of the fluorescence intensity distribution curve of the capillary channel of Example 4 and the concentration.

[0065] Figure 21 This is the fluorescence intensity distribution diagram at the capillary channel of Example 5.

[0066] Figure 22 3 is a linear fitting graph of the absolute value of the fitting slope of the fluorescence intensity distribution curve of the capillary channel of Example 5 and the concentration.

[0067] Figure 23 This is a distribution diagram of the grayscale values of the color at the color development wells of the enzyme-catalyzed reaction of HRP and TMB at different concentrations in Example 6.

[0068] Figure 24 This is the linear fitting result of the average grayscale value at the color development well in Example 6 and the logarithm of the HRP concentration.

[0069] Figure 25 This is a schematic diagram of the immune competition reaction principle of Example 6.

[0070] Figure 26a Graph showing the complete mixing distance of three different microreactors under different Reynolds numbers.

[0071] Figure 26b Graph showing the complete mixing distance of two different microreactors under different Reynolds number conditions.

[0072] Figure 26c This is a diagram of the complete mixing time of different microreactors under different Reynolds number conditions.

[0073] Figure 26d This is a diagram of the complete mixing time of the T-type microreactor under different Reynolds number conditions.

[0074] Figure 27 Graph showing the mixing effect under different semi-major axis a1 conditions.

[0075] Figure 28 Graph showing the mixing effect under different semi-major axis a3 conditions.

[0076] Figure 29 The figure shows the mixing effect under different flow channel angles.

[0077] Figure 30a This is a diagram of the product situation of the T-type microreactor under different Reynolds number conditions.

[0078] Figure 30b This is a diagram of the product situation of the SAR microreactor under different Reynolds number conditions.

[0079] Figure 30c This is a diagram of the product status of the microreactor (3D-HM) of Example 1 under different Reynolds number conditions.

[0080] Figure 31a This is a simulation cloud diagram of the mixing situation of the SAR type microreactor.

[0081] Figure 31b This is a simulation cloud diagram of the mixing condition of the microreactor in Example 1.

[0082] Figure 32a This is a microscope photograph of the mixing of methylene blue and water in the microreactor of Example 1.

[0083] Figure 32b This is a microscope photograph of the mixing condition of NaOH and phenolphthalein in the microreactor of Example 1.

[0084] In the figure, mixing efficiency refers to the degree of complete mixing between different substances. DETAILED DESCRIPTION

[0085] The present invention will be described in detail below with reference to the following embodiments. It should be noted that the embodiments and features of the embodiments may be combined unless they conflict. For ease of description, the words "upper," "lower," "left," and "right" appearing below merely indicate the directions of upper, lower, left, and right relative to the accompanying drawings and do not limit the structure.

[0086] Example 1

[0087] See also Figure 1 and Figure 2 A microreactor comprises a substrate 4 and a cover plate 3. The top surface of the substrate 4 is provided with a main channel 6 and six flow channels 7 that are connected in sequence, and the flow channels 7 are connected in series in sequence; the cover plate 3 is bonded to the top of the substrate 4; optionally, the substrate and cover plate can be made of materials such as polymethyl methacrylate (PMMA), polydimethylsiloxane (PDMS) or glass (PMMA is selected in this embodiment);

[0088] The cross section of the flow channel is rectangular, and the flow channel has a first side wall, a second side wall, a third side wall and a fourth side wall, and the first side wall, the second side wall, the third side wall and the fourth side wall are adjacent to each other in sequence to form the flow channel;

[0089] A first protrusion 701 in a semi-elliptical shape is provided on the first side wall and is in communication with the flow channel. The length direction of the first protrusion 701 is perpendicular to the length direction of the flow channel and parallel to the first side wall. A first diverter 702 in a semi-elliptical shape is provided in the flow channel. The first diverter 702 protrudes in the direction of the first protrusion 701. Gaps are left between the first diverter 702 and the first side wall, and between the first diverter 702 and the third side wall. The length direction of the first diverter 702 is parallel to the length direction of the first protrusion 701. The central axis of the first protrusion 701 and the central axis of the first diverter 702 are located in the same plane, and the plane is perpendicular to the length direction of the flow channel.

[0090] The second side wall is provided with a second protrusion 703 in a semi-elliptical shape that is in communication with the flow channel. The length direction of the second protrusion 703 is perpendicular to the length direction of the flow channel and parallel to the second side wall. The fourth side wall is provided with a third protrusion 704 in a semi-elliptical shape that is in communication with the flow channel. The length direction of the third protrusion 704 is perpendicular to the length direction of the flow channel and parallel to the fourth side wall. The second protrusion 703 and the third protrusion 704 are symmetrically distributed along the length direction of the flow channel.

[0091] The third side wall is provided with a fourth protrusion 705 in a semi-elliptical shape that is connected to the flow channel. The length direction of the fourth protrusion 705 is perpendicular to the length direction of the flow channel and parallel to the third side wall. A second diverter 706 in a semi-elliptical shape is provided in the flow channel. The second diverter 706 protrudes in the direction of the fourth protrusion 705. There is a gap between the second diverter 706 and the first side wall and between the second diverter 706 and the third side wall. The length direction of the second diverter 706 is parallel to the length direction of the fourth protrusion 705. The central axis of the fourth protrusion 705 and the central axis of the second diverter 706 are located in the same plane, and the plane is perpendicular to the length direction of the flow channel.

[0092] Viewed along the length of the flow channel, oppositely disposed second protrusions 703 and third protrusions 704 are provided between adjacent first protrusions 701 and fourth protrusions 705 , and a first protrusion 701 or a fourth protrusion 705 is provided between two adjacent second protrusions 703 .

[0093] The angle between two adjacent flow channels is 90°, so that the channel formed by connecting the flow channels 7 is zigzag-shaped.

[0094] The axis parallel to the length direction of the flow channel is taken as the semi-major axis of the ellipse, and the axis perpendicular to the length direction of the flow channel is taken as the semi-minor axis of the ellipse. The semi-major axis a1 of the first protrusion 701 and the fourth protrusion 705 is 0.25 mm, and the semi-minor axis b1 is 0.4 mm. The distance W between the central axis of the first protrusion 701 and the central axis of the fourth protrusion 705 in the length direction of the corresponding flow channel is 0.8 mm; the semi-major axis a2 of the diverter is 0.25 mm, and the semi-minor axis b2 is 0.2 mm; the semi-major axis a3 of the second protrusion 703 and the third protrusion 704 is 0.1 mm, and the semi-minor axis b3 is 0.2 mm. The distance between the central axis of the second protrusion 703 and the central axis of the first protrusion 701 in the length direction of the corresponding flow channel is 0.4 mm, and the distance between the central axis of the second protrusion 703 and the central axis of the fourth protrusion 705 in the length direction of the corresponding flow channel is 0.4 mm.

[0095] Viewed along the length direction of the flow channel, the flow channel is provided with a first protrusion 701, a second protrusion 703 and a third protrusion 704 arranged opposite to each other, a fourth protrusion 705 and a second protrusion 703 in sequence. A first diversion portion is provided in the flow channel corresponding to the first protrusion 701, and a second diversion portion is provided in the flow channel corresponding to the fourth protrusion 705.

[0096] The device also includes at least two inlet channels 5, one end of which communicates with the main channel 6. The cover plate 3 is provided with two liquid inlet holes 1 and one liquid outlet hole 2, each of which communicates with the other end of the inlet channels 5. It also includes an outlet channel 8, the inlet end of which communicates with the outlet end of the last flow channel 7, and the liquid outlet hole 2 communicates with the outlet end of the outlet channel. The main channel 6 and the outlet channel 8 share a common central axis. The main channel 6 is 0.2 mm long, each flow channel is 2 mm long, and the outlet channel is 1.8 mm long.

[0097] When making a microreactor, an engraving machine can be used to engrave relevant microchannels on the substrate, and the substrate and the cover plate can be bonded using a hot press bonding method.

[0098] Comparative Example 1

[0099] Repeat Example 1, see Figure 4 The only difference is that the number of flow channels is 1, and the value of the semi-minor axis b1 is changed to analyze the mixing efficiency at the outlet section.

[0100] Depend on Figure 4 It can be seen that controlling the semi-minor axis b1 within 0.15-0.5 mm is helpful to obtain high mixing efficiency and low pressure drop.

[0101] Comparative Example 2

[0102] Repeat Example 1, see Figure 27 The only difference is that the number of flow channels is 1, and the value of the semi-major axis a1 is changed to analyze the mixing efficiency at the outlet section.

[0103] Depend on Figure 4 It can be seen that controlling the semi-major axis a1 within 0.15-0.3 mm is helpful to obtain high mixing efficiency.

[0104] Comparative Example 3

[0105] Repeat Example 1, see Figure 5 The only difference is that the number of flow channels is 1, and the distance W between the central axis of the first protrusion 701 and the central axis of the fourth protrusion 705 in the length direction of the corresponding flow channel is changed to analyze the mixing efficiency at the outlet cross section.

[0106] Depend on Figure 5It can be seen that controlling W within 0.75-0.8 mm or 0.9-1.25 mm is helpful to obtain high mixing efficiency and low pressure drop.

[0107] Comparative Example 4

[0108] Repeat Example 1, see Figure 6 The only difference is that the number of flow channels is 1, and the value of the semi-major axis a2 is changed to analyze the mixing efficiency at the outlet section.

[0109] Depend on Figure 6 It can be seen that controlling the semi-major axis a2 within 0.05-0.25 mm, especially 0.05-0.15 mm, helps to achieve high mixing efficiency and low pressure drop at the same time.

[0110] Comparative Example 5

[0111] Repeat Example 1, see Figure 7 The only difference is that the number of flow channels is 1, and the value of the semi-minor axis b2 is changed. The other conditions remain unchanged. The mixing efficiency at the outlet section is analyzed.

[0112] Depend on Figure 7 It can be seen that controlling the semi-minor axis b2 within 0.1-0.3 mm helps to achieve high mixing efficiency at the same time.

[0113] Comparative Example 6

[0114] Repeat Example 1, see Figure 8 The only difference is that the number of flow channels is 1, the shape of the diversion part is changed, and the mixing efficiency at the outlet cross section is analyzed.

[0115] Depend on Figure 8 It can be seen that selecting a semi-elliptical column-shaped flow dividing portion helps to improve the mixing efficiency.

[0116] Comparative Example 7

[0117] Repeat Example 1, see Figure 9 The only difference is that the number of flow channels is 1, and the value of the semi-minor axis b3 is changed to analyze the mixing efficiency at the outlet section.

[0118] Depend on Figure 9 It can be seen that when the semi-minor axis b3 is 0.1-0.3 mm, it helps to obtain particularly high mixing efficiency.

[0119] Comparative Example 8

[0120] Repeat Example 1, see Figure 28 The only difference is that the number of flow channels is 1, and the value of the semi-major axis a3 is changed to analyze the mixing efficiency at the outlet section.

[0121] Depend on Figure 9 It can be seen that when the semi-major axis a3 is 0.05-0.12 mm, it helps to obtain particularly high mixing efficiency.

[0122] Comparative Example 9

[0123] Repeat Example 1, see Figure 29 The only difference is that the number of flow channels is 2, and the angle between two adjacent flow channels is 60-120°.

[0124] Depend on Figure 29 It can be seen that the mixing efficiency is highest at 90°.

[0125] Example 2

[0126] Numerical simulation of the microreactor under a wide range of Reynolds numbers is performed. When the homogeneous microreactor provided in Example 1 is working, the plane where the inlet channel is located is taken as the xy plane, and the two liquid inlet holes 1 are respectively introduced with aqueous solutions of the same flow rate (Re=0.1-100), wherein the concentration of one inlet is set to 1, and the concentration of the other inlet is set to 0, and the two fluids flow from the liquid inlet hole 1 into the inlet channel 5, and then merge into the main channel 6 to mix. At this time, the laminar flow phenomenon is relatively stable, and the two fluids are mainly diffusely mixed. The main mixing area of the fluid is in the flow channel 7. The stable laminar flow enters the flow channel 7 from the main channel, and is first affected by the first diversion part 702. The fluid is divided into two streams, one of which enters the first convex part 701 and is affected by the expansion of the secondary flow structure (first convex part) in the y direction. The fluid is stretched, resulting in a flow direction different from the mainstream flow. The second and third protrusions 703 and 704 are in the z-direction. Under the influence of the expansion of the second and third protrusions 703 and 704 in the z-direction, the fluid is stretched to produce a secondary flow with a different flow direction from the mainstream, which impacts the mainstream in the xy plane, and then enters the fourth protrusion 705 with the opposite stretching direction. Similarly, the secondary flow effect produced has an impact on the mainstream. Similarly, it flows through the second and third protrusions 703 and 704 again, and the secondary flow effect produced has an impact on the mainstream in the xy plane. In one mixing cycle, four secondary flows in different directions are generated, which maximize the degree of fluid chaos within a short mixing distance. Then, the fluid flows through the next channel and the corner 9 between the channels. Under the influence of chaotic convection caused by the drastic change in the direction of the main channel, the fluid motion pattern is further changed and the degree of mixing is further enhanced. After three mixing cycles, the two fluids are almost completely mixed. Then, the mixed fluid flows into the outlet channel 8 and flows out from the liquid outlet 2. The mixing efficiency is obtained by analyzing the outlet cross section. The mixing distance and mixing time of the T-type microreactor are calculated using the existing formula. Where v is the velocity of the liquid flow, w is the width of the channel, and D is the diffusion coefficient of the liquid. Due to the particularity of the T-shaped channel, the liquid diffuses perpendicular to the flow direction, so a long distance is required for complete mixing in the T-shaped channel. Using COMSOL 6.0 and setting the above concentration parameters, a fluid mechanics simulation of the SAR (splitting and recombination type) microreactor and the microreactor of the present invention was performed. By observing the result cloud map, the cloud map changes from two distinct colors of red and blue to completely mixed green, and the mixing distance when the two liquids are completely mixed is obtained. The mixing time is obtained by dividing the distance by the flow rate, see Figure 31

[0127] In addition, use the chromogenic reaction of NaOH and phenolphthalein, the hybrid reaction of methyl blue (5mM) and water verifies the reliability of microreactor simulation result of the present invention. NaOH solution (150mM) and phenolphthalein solution (10mM) are passed through respectively by two entrances, due to laminar flow, show as both sides transparent solution at the entrance, but present pink at its interface, observe the variation of pink solution width, can think that completely mix when pink solution is almost full of passage, from entrance to being full of complete mixing distance, obtain complete mixing time with this distance divided by inlet velocity (speed is drawn according to Reynolds number). The result that the hybrid reaction of methyl blue and water draws is extremely close to the result of NaOH and phenolphthalein; As can be seen from Figure 31 and Figure 32, employed simulation result can accurately reflect real situation, so the result of the mixing distance and mixing time of the microreactor of embodiment 1 using simulation result estimation is reliable. The result of T-type microreactor is drawn by formula.

[0128] Referring to Figure 26, the complete mixing distance and complete mixing time of the T-type microreactor (obtained by calculation), the fission and recombination (SAR) type microreactor (obtained by simulation) and the microreactor described in Example 1 of the present invention (obtained by simulation) are compared. The results show that the microreactor of the present invention has a shorter complete mixing distance of approximately 7.2 mm and a shorter complete mixing time of approximately 3.4 ms compared with the other two microreactors, which indicates that the microreactor of the present invention can complete the mixing reaction of the two substances in a shorter time and distance, that is, the present invention has a higher mixing intensity.

[0129] Comparative Example 10

[0130] Example 2 was repeated except that a T-shaped microreactor of the same size was used (the flow channel was a single linear channel, and the relevant protrusions and diverters were omitted). All other conditions and operating steps were the same, and the outlet cross-section was analyzed to determine the mixing efficiency under the Reynolds number range (Re = 0.1-100).

[0131] Comparative Example 11

[0132] Example 2 was repeated, except that the angle between adjacent flow channels was 180° (the channels were now linear overall), and the second and third raised portions 703 and 704 were omitted. This was referred to as a "two-dimensional linear microreactor." All other conditions and procedures remained the same, and the outlet cross-section was analyzed to determine mixing efficiency over a range of Reynolds numbers (Re = 0.1-100).

[0133] Comparative Example 12

[0134] Example 2 was repeated, with the only difference being that the angle between two adjacent flow channels was 180°, and this was designated as a "three-dimensional linear microreactor." All other conditions and procedures remained the same, and the outlet cross-section was analyzed to determine the mixing efficiency over a range of Reynolds numbers (Re = 0.1-100).

[0135] Depend on Figure 10 It can be seen that the mixing efficiency of the microreactor of Example 1 is better than that of other microreactors under various Reynolds number conditions.

[0136] Example 3

[0137] See also Figure 11 , using the microreactor described in Example 1 to prepare zinc-based MOF nanoparticles, comprising the following steps:

[0138] Providing reaction solution 18 (zinc acetate dihydrate solution) and reaction solution 19 (2-methylimidazole solution);

[0139] The concentration of zinc acetate dihydrate in the zinc acetate dihydrate solution is 10 mM, and the total amount is 20 mL; the concentration of 2-methylimidazole in the 2-methylimidazole solution is 40 mM, and the total amount is 20 mL.

[0140] Zinc acetate dihydrate and 2-methylimidazole were used as raw materials for preparing zinc-based MOF (ZIF-8). An injection pump and a hose were used to connect the two liquid inlets of the microreactor 11. The Reynolds numbers of different groups were set to 100 and 500, respectively. The two liquid inlets were injected at equal flow rates. The mixed liquid flowed out of the liquid outlet after three mixing cycles in the microreaction area 20. The reaction solution was collected using a centrifuge tube, which was placed in a centrifuge. The centrifuge was used to centrifuge the mixed liquid at a speed of 12,000 rpm for 1.5 hours until the supernatant was clear and transparent. The supernatant was precipitated and separated at the bottom, and the precipitate was dried using a constant temperature box to obtain product 10 (ZIF-8).

[0141] See also Figure 13 The pure ZIF-8 prepared in Example 3 was photographed using a scanning electron microscope, and it was observed that the product morphology was relatively uniform spherical particles with high yield and uniform particle size distribution. When the Reynolds number was 100, the particle size of the obtained product was about 200 nm, and when the Reynolds number was 500, the particle size of the obtained product was about 150 nm. It can be seen that the use of the microreactor of the present invention, combined with the adjustment of the Reynolds number, can adjust the product particle size.

[0142] According to the literature [1], even when ZIF-8 is prepared using a SAR microreactor under turbulent jet conditions, when the residence time of the reactants in the microreactor is 700 ms, the particle size of the prepared ZIF-8 reaches about 500 nm, which is much larger than the particle size of the ZIF-8 prepared in the present invention.

[0143] In addition, comparative experiments have shown that the use of the microreactor of the present invention helps to obtain a higher yield of products, while when using a T-type microreactor or a SAR-type microreactor, the product yield is relatively small, see Figure 30.

[0144] Comparative Example 13

[0145] Example 3 was repeated except that a mixture of zinc acetate dihydrate and sodium fluorescein was used as the reaction solution 18. The remaining steps were the same, and ZIF-8 loaded with sodium fluorescein was obtained after drying.

[0146] See also Figure 12 The infrared spectra of pure ZIF-8 and sodium fluorescein-loaded ZIF-8 were compared with those of pure sodium fluorescein, confirming that sodium fluorescein was successfully encapsulated into ZIF-8.

[0147] Comparative Example 14

[0148] Example 3 was repeated except that a mixture of zinc acetate dihydrate and sodium fluorescein was used as the reaction solution 18, and both a T-type microreactor and a SAR-type microreactor were used for the preparation. ZIF-8 loaded with sodium fluorescein was prepared at Reynolds numbers of 50, 200, 500, 700, 900, and 1100, respectively.

[0149] See also Figure 14 The concentration of sodium fluorescein contained in the supernatant of each group of products was measured. As can be seen from the figure, the absorbance value of the supernatant of the product of the microreactor of the present invention is lower, which proves that the high reaction intensity homogeneous microreactor (3D-HM) of the present invention can prepare more ZIF-8 loaded with sodium fluorescein.

[0150] See also Figure 15 The fluorescence intensity of the supernatant of each group of products was measured using a fluorescence inverted microscope. The results showed that the product prepared by the present invention encapsulated more sodium fluorescein into ZIF-8, reflecting the superiority of the high encapsulation rate of the prepared product.

[0151] Example 4

[0152] See also Figure 10The microreactor of this embodiment has the same inlet channel and flow channel structure as the microreactor of Example 1, with the main difference being that the number of flow channels is 4, and the microreactor of this embodiment further comprises an amplification unit 12 and a plurality of capillary channels 13 and a color development hole 14 having the same number as the capillary channels 13, wherein the amplification unit 12 comprises a straight channel having a central axis coaxial with the main channel 6, the inlet end of the straight channel being connected to the outlet end of the last flow channel 7, and a separator is provided in the outlet end of the straight channel, which divides the outlet end into two symmetrically distributed sub-channels. At the outlet end, the two sub-outlet ends are respectively connected to an arc segment, and the outlet section of each arc segment is respectively connected to an amplification channel 1201. The two amplification channels 1201 are symmetrically distributed along the central axis of the straight channel. One end of the multiple capillary channels 13 is connected to the amplification channel 1201, and the other ends of the multiple capillary channels 13 are respectively connected to a color development hole 14; the connection positions of each capillary channel 13 on the amplification channel 1201 are symmetrically distributed along the central axis of the amplification unit 12, thus forming a "human" shaped amplification structure.

[0153] The cross section of the amplification channel 1201 is rectangular, with a width of 0.8 mm and a depth of 0.3 mm.

[0154] The number of capillary channels 13 is 19, and the cross section of the capillary channel 13 is rectangular, with a width of 0.1 mm and a depth of 0.1 mm;

[0155] The capillary channel 13 includes a first capillary segment and a second capillary segment that are sequentially connected. The first capillary segment is connected to the amplification unit 12, and the second capillary segment is connected to a color development hole 14. The first capillary segments are parallel to each other, and the center distance between adjacent first capillary segments is 0.3 mm.

[0156] The color developing hole 14 is cylindrical, and its radius is 0.5 mm; the center distance between adjacent color developing holes 14 is 1.1 mm.

[0157] Fluorescein sodium and distilled water are used as verification reagents to verify the application potential of the microreactor of the present invention in immunoassay. When the high reaction intensity homogeneous microreactor provided in this example is used for immunoassay, 10mL of 0.001mM fluorescein sodium and 10mL of distilled water are respectively introduced through two inlet channels 5 at a low flow rate (Re=2). Fluorescein sodium and water diffuse and mix in flow channel 7 to simulate the diffusion reaction of antigen and antibody in the microreactor. The mixed solution is initially amplified into the laminar flow state at the outlet by the channel amplification unit 12, and then flows into the capillary channel 13. The mixed solution distribution of the capillary channel 13 reflects the laminar flow state at the outlet of the last flow channel 7. Subsequently, a fluorescence image at the capillary channel place is captured using a fluorescence inverted microscope, and the fluorescence intensity value on each channel is read using fluorescence analysis software.

[0158] Comparative Example 15

[0159] Example 4 was repeated except that a 0.002 mM fluorescein sodium solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0160] Comparative Example 16

[0161] Example 4 was repeated except that a 0.003 mM fluorescein sodium solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0162] Comparative Example 17

[0163] Example 4 was repeated except that a 0.004 mM fluorescein sodium solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0164] Comparative Example 18

[0165] Example 4 was repeated except that a 0.005 mM sodium fluorescein solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0166] See also Figure 19 The fluorescence intensity distribution in the capillary channel of sodium fluorescein and distilled water at different concentrations at low Reynolds number (Re=2) was compared. As the concentration of sodium fluorescein increased, the distribution trend of fluorescence intensity was similar, and the fluorescence intensity value gradually increased.

[0167] See also Figure 20 The fluorescence intensity distribution curves at different concentrations obtained in Example 4 were linearly fitted. The absolute value of the slope of each fitted line was taken, and a linear fit was performed on the absolute value of the slope to analyze the linear relationship between the concentration and the absolute value of the slope. The linear fitting results indicate that the microreactor has potential for application in immunoassays.

[0168] Example 5

[0169] See also Figure 18 The microreactor of this embodiment has the same flow channel and other structures as the microreactor of Example 1, with the main difference being that the number of flow channels is four, and the microreactor of this embodiment further includes two liquid reservoirs 15, two trigger valves 17, and one trigger channel 16. The liquid reservoirs 15, the trigger valves 17, and the main channel 6 are sequentially connected, and the trigger channel 16 is connected to the main channel 6.

[0170] The area of the liquid reservoir 15 is 4 mm 2, the depth is 0.1mm; the area of the trigger valve 17 is 0.3mm 2 , with a depth of 0.1 mm; the trigger channel 16 has a width of 0.1 mm and a depth of 0.3 mm.

[0171] Next, to verify the enhancement of the diffusion reaction by capillary pump drive, 10 mL of 0.001 mM sodium fluorescein solution and 10 mL of distilled water were dripped into two reservoirs 15, respectively. Fluorescence images of the capillary channels were captured using an inverted fluorescence microscope, and fluorescence intensity values for each channel were read using fluorescence analysis software.

[0172] Comparative Example 19

[0173] Example 5 was repeated except that a 0.002 mM fluorescein sodium solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0174] Comparative Example 20

[0175] Example 5 was repeated except that a 0.003 mM fluorescein sodium solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0176] Comparative Example 21

[0177] Example 5 was repeated except that a 0.004 mM fluorescein sodium solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0178] Comparative Example 22

[0179] Example 5 was repeated except that a 0.005 mM fluorescein sodium solution was used. Other conditions and operating steps were the same, and the fluorescence intensity values on the capillary channel were analyzed using fluorescence analysis software.

[0180] See also Figure 19 The fluorescence intensity distribution in the capillary channel of sodium fluorescein and distilled water at different concentrations driven by a capillary pump was compared. As the concentration of sodium fluorescein increased, the distribution trend of fluorescence intensity was similar to the result of using a syringe pump, and the fluorescence intensity value gradually increased.

[0181] See also Figure 20 , perform linear fitting on the fluorescence intensity distribution curves at different concentrations obtained in Example 5, take the absolute value of the slope of each fitting line, perform linear fitting on the absolute value of the slope, and analyze the linear relationship between the concentration and the absolute value of the slope.

[0182] Example 6

[0183] The immune reaction was generated by using 1 mL of single-component TMB and different concentration gradients (0 ng / mL, 0.0001 ng / mL, 0.001 ng / mL, 0.01 ng / mL, 0.1 ng / mL, 1 ng / mL, 1 mL) of horseradish peroxidase (HRP). The cells were introduced into the tube using a syringe pump at a low Reynolds number (Re = 2). Figure 18 In the microreactor shown, the introduction time is 30 s. After the color development well 14 is filled with the reaction solution, an image is taken using a smartphone, and the grayscale value of each outlet area under different HRP concentrations is analyzed using image analysis software.

[0184] See also Figure 23 The grayscale values of the color development well 14 were compared at low Reynolds number (Re=2) for HRP and single-component TMB at different concentrations. As the HRP concentration increased, the grayscale value of the reaction solution at the outlet gradually decreased, with the 0 ng / mL control group having the highest grayscale value of the outlet color.

[0185] See also Figure 24 The average grayscale value of the color-developing well 14 under different concentration gradients was linearly fitted, and there was a good linear relationship between the average grayscale value and the logarithm of the HRP concentration, which confirmed the potential of the microreactor of the present invention for application in immunoassay.

[0186] See also Figure 25 , a schematic diagram of a process for applying the microreactor and T-type microreactor of the present invention to POCT detection of competitive immunoassay:

[0187] The labeled antigen is mixed with the antigen to be tested and introduced into two microreactors from one reservoir, while the bound antibody is introduced into the two microreactors from another reservoir. Due to the laminar flow phenomenon under low Reynolds number, the antigen and antibody between the fluids on both sides undergo weak diffusion binding. Since the antigen to be tested competes for the bound antibody of the labeled antigen, the inverted labeled antigen moves to the other side of the laminar flow, which leads to a change in the color area.

[0188] In the T-type microreactor, due to the relatively stable laminar flow, the diffusion reaction of antigen and antibody is extremely weak, resulting in a small number of antigens binding to the antibody, and only a small amount of labeled antigen moves to the other side, which may lead to false negative test results.

[0189] Through the application of the microreactor of the present invention, due to the influence of the microreaction structure, the diffusion reaction is strong at low Reynolds numbers, more test antigens compete with the labeled antigens, resulting in a large number of labeled antigens moving to the other side, which leads to a significant change in the color area, which is conducive to the detection of low concentrations of test antigens, avoids the generation of false negatives, and improves the accuracy of POCT detection.

[0190] In summary, the present invention maximizes the intensity of the reaction within the microreactor over a short distance by designing a homogeneous microreactor with high reaction intensity, introducing a three-dimensional secondary flow structure, and combining it with other structures. Furthermore, the microreactor of the present invention has promising application prospects in the field of immunoassays, enabling the detection of low-concentration analytes and avoiding the generation of false negatives.

[0191] References:

[0192] [1] N. Rohra, G. Gaikwad, P. Dandekar, R. Jain, Microfluidic Synthesis of aBioactive Metal-Organic Framework for Glucose-Responsive Insulin Delivery, ACSAppl.Mater.Interfaces 14(6)(2022)8251-8265. https: / / doi.org / 10.1021 / acsami.1c22153 .

[0193] The contents illustrated in the above embodiments should be understood as these embodiments are only used to more clearly illustrate the present invention, and are not used to limit the scope of the present invention. After reading the present invention, various equivalent modifications of the present invention by those skilled in the art shall fall within the scope defined by the claims attached to this application.

Claims

1. A microreactor comprising a main channel (6) and at least two flow channels (7) connected in sequence, wherein the flow channels (7) are connected in series; characterized in that: The cross section of the flow channel is rectangular, and the flow channel has a first side wall, a second side wall, a third side wall and a fourth side wall, and the first side wall, the second side wall, the third side wall and the fourth side wall are adjacent to each other in sequence to form the flow channel; The first side wall is provided with a first protrusion (701) in a semi-elliptical shape and communicating with the flow channel, the length direction of the first protrusion (701) is perpendicular to the length direction of the flow channel and parallel to the first side wall, a first diverter (702) in a semi-elliptical shape is provided in the flow channel, the first diverter (702) is protruding in the direction of the first protrusion (701), a gap is left between the first diverter (702) and the first side wall, and between the first diverter (702) and the third side wall, the length direction of the first diverter (702) is parallel to the length direction of the first protrusion (701), the central axis of the first protrusion (701) and the central axis of the first diverter (702) are located on the same plane, and the plane is perpendicular to the length direction of the flow channel; The second side wall is provided with a second convex portion (703) in a semi-elliptical shape and communicating with the flow channel, the length direction of the second convex portion (703) being perpendicular to the length direction of the flow channel and parallel to the second side wall; the fourth side wall is provided with a third convex portion (704) in a semi-elliptical shape and communicating with the flow channel, the length direction of the third convex portion (704) being perpendicular to the length direction of the flow channel and parallel to the fourth side wall; the second convex portion (703) and the third convex portion (704) are symmetrically distributed along the length direction of the flow channel; The third side wall is provided with a fourth protrusion (705) in a semi-elliptical shape and connected to the flow channel, the length direction of the fourth protrusion (705) is perpendicular to the length direction of the flow channel and parallel to the third side wall, and a second diverter (706) in a semi-elliptical shape is provided in the flow channel, the second diverter (706) is protruded in the direction of the fourth protrusion (705), and there are gaps between the second diverter (706) and the first side wall, and between the second diverter (706) and the third side wall, the length direction of the second diverter (706) is parallel to the length direction of the fourth protrusion (705), the central axis of the fourth protrusion (705) and the central axis of the second diverter (706) are located on the same plane, and the plane is perpendicular to the length direction of the flow channel; Viewed along the length direction of the flow channel, the first raised portion (701) and the fourth raised portion (705) are arranged in sequence, a second raised portion (703) and a third raised portion (704) arranged opposite to each other are provided between adjacent first raised portions (701) and fourth raised portions (705), and a first raised portion (701) or a fourth raised portion (705) is provided between two adjacent second raised portions (703).

2. The microreactor according to claim 1, characterized in that The angle between two adjacent flow channels (7) is 60-120°.

3. The microreactor according to claim 2, characterized in that The angle between two adjacent flow channels (7) is 80-110°.

4. The microreactor according to claim 3, characterized in that The angle between two adjacent flow channels (7) is 90°.

5. The microreactor according to claim 1, characterized in that The axis parallel to the length direction of the flow channel is taken as the semi-major axis of the ellipse, and the axis perpendicular to the length direction of the flow channel is taken as the semi-minor axis of the ellipse. The semi-major axis a1 of the first protrusion (701) and the fourth protrusion (705) is 0.05-0.25 mm, and the semi-minor axis b1 is 0.05-0.5 mm. The distance W between the central axis of the first protrusion (701) and the central axis of the fourth protrusion (705) in the length direction of the corresponding flow channel is 0.6-1.25 mm; the semi-major axis a2 of the diverter is 0.05-0.25 mm, and the semi-minor axis b2 is 0.05-0.3 mm; the semi-major axis a3 of the second protrusion (703) and the third protrusion (704) is 0.08-0.12 mm, and the semi-minor axis b3 is 0.05 mm-0.3 mm.

6. The microreactor according to any one of claims 1 to 5, characterized in that It also includes at least two inlet channels (5), one end of each of the inlet channels (5) being in communication with the main channel (6).

7. The microreactor according to any one of claims 1 to 5, characterized in that It also includes an outlet channel (8), the inlet end of the outlet channel (8) is connected to the outlet end of the last flow channel (7).

8. The microreactor according to any one of claims 1 to 5, characterized in that The invention also includes an amplification unit (12) and a plurality of capillary channels (13) and color development holes (14) having the same number as the capillary channels (13). The amplification unit (12) includes a straight channel having a common central axis with the main channel (6). The inlet end of the straight channel is connected to the outlet end of the last flow channel (7). A separator is provided in the outlet end of the straight channel. The separator separates the outlet end into two symmetrically distributed sub-outlet ends. The two sub-outlet ends are respectively connected to an arc segment. The outlet end of each arc segment is respectively connected to an amplification channel (1201). The two amplification channels (1201) are symmetrically distributed along the central axis of the straight channel. One end of the plurality of capillary channels (13) is connected to the amplification channel (1201), and the other end of the plurality of capillary channels (13) is respectively connected to a color development hole (14); the connection position of each capillary channel (13) on the amplification channel (1201) is symmetrically distributed along the central axis of the amplification unit (12).

9. The microreactor according to claim 8, characterized in that The cross section of the amplification channel (1201) is rectangular, with a width of 0.5-1.2 mm and a depth of 0.1-0.4 mm.

10. The microreactor according to claim 9, characterized in that The width of the amplification channel (1201) is 0.6-1 mm; the depth is 0.2-0.3 mm.

11. The microreactor according to claim 9, characterized in that The number of capillary channels (13) is 15-25.

12. The microreactor according to claim 11, characterized in that The number of capillary channels (13) is 17-21.

13. The microreactor according to claim 11, characterized in that The cross section of the capillary channel (13) is rectangular, with a width of 0.05-2 mm and a depth of 0.05-0.2 mm.

14. The microreactor according to claim 9, characterized in that The capillary channel (13) includes a first capillary segment and a second capillary segment that are connected in sequence, the first capillary segment is connected to the amplification unit (12), and the second capillary segment is connected to a color development hole (14), the first capillary segments are parallel to each other, and the distance between adjacent first capillary segments is 0.2-0.45 mm.

15. The microreactor according to claim 9, characterized in that The color development hole (14) is cylindrical, and its radius is 0.3-0.7 mm.

16. The microreactor according to claim 9, characterized in that The center distance between adjacent color-developing holes (14) is 0.65-1.45 mm.

17. The microreactor according to claim 8, characterized in that It also includes a liquid storage tank (15), a trigger valve (17) and a trigger channel (16), wherein the liquid storage tank (15), the trigger valve (17) and the main channel (6) are connected in sequence, and the trigger channel (16) is connected to the main channel (6).

18. The microreactor according to claim 17, characterized in that The area of the liquid reservoir (15) is 2-6 mm 2 , the depth is 0.15-0.45mm.

19. The microreactor according to claim 17, characterized in that The area of the trigger valve (17) is 0.15-0.45 mm 2 , the depth is 0.08-0.12mm.

20. The microreactor according to claim 17, characterized in that The trigger channel (16) has a width of 0.8-0.12 mm and a depth of 0.15-0.45 mm.

21. A method for preparing nanoparticles using the microreactor according to any one of claims 1 to 7, characterized in that: The steps include: (1) The raw material solution is fed into the main channel (6), and the reaction solution is collected at the outlet of the last flow channel (7); (2) The reaction solution is subjected to solid-liquid separation to obtain a precipitated substrate, which is then dried to obtain nanoparticles.

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