Microfluidic mixer and microfluidic chip

Abstract

A microfluidic mixer and a microfluidic chip. The microfluidic mixer comprises: mixing units (10), each comprising an inlet end (1), an outlet end (2) and two channels (3), wherein inlets of the two channels (3) are both connected to the inlet end (1), and outlets of the two channels (3) are both connected to the outlet end (2); and on a cross section cut along a fluid flow direction, at least one of the two channels (3) comprises two side walls (31), the at least one side wall (31) comprises a first side wall section (301) and a second side wall section (302), the first side wall section (301) and the second side wall section (302) have different centers of curvature, the first side wall section (301) is an arc-shaped section, and the first side wall section (301) and the second side wall section (302) intersect to form a first corner portion (321).

Description

Microfluidic mixer and microfluidic chip

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] The present disclosure claims priority to PCT international application No. PCT / CN2023 / 143148, filed on December 29, 2023, entitled “Microfluidic Mixer and Microfluidic Chip,” the entire contents of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of microfluidics, and in particular to a microfluidic mixer and a microfluidic chip, which can quickly and effectively mix liquid microfluids or be used to manufacture nanoparticles, such as liposomes, lipid nanoparticles (LNPs), or poly(lactic-co-glycolic acid) (PLGA) nanoparticles. Background Art

[0004] The formation mechanism of nucleic acid-loaded lipid nanoparticles (LNPs) is achieved by mixing and diluting the lipid components in the organic phase and the nucleic acid components in the aqueous phase, reducing the organic phase concentration and promoting the self-assembly of the phospholipid and nucleic acid components. Different organic phase concentrations can produce nanoparticles with different morphologies, such as spheres, films, and tubes. Furthermore, organic phase concentration can significantly affect the overall nanoparticle encapsulation efficiency, size, and particle size distribution. Therefore, improving mixing efficiency and ensuring that the mixed solution instantly reaches a specific organic phase concentration is crucial to the quality of the resulting nanoparticles.

[0005] Summary of the Invention

[0006] Some embodiments of the present disclosure provide a microfluidic mixer and a microfluidic chip for improving mixing efficiency.

[0007] In one aspect of the present disclosure, a microfluidic mixer is provided, comprising: a mixing unit, comprising an inlet end, an outlet end and two channels, the inlets of the two channels are both connected to the inlet end, and the outlets of the two channels are both connected to the outlet end; in a cross-section cut along the direction of fluid flow, at least one of the two channels comprises two side walls, at least one side wall comprises a first side wall segment and a second side wall segment, the first side wall segment and the second side wall segment have different centers of curvature, the first side wall segment is an arc segment, and the first side wall segment intersects with the second side wall segment to form a first corner.

[0008] In some embodiments, the second sidewall segment is a straight line segment.

[0009] In some embodiments, the first corner is a curved corner.

[0010] In some embodiments, both the first sidewall segment and the second sidewall segment extend smoothly from the inlet end to the outlet end.

[0011] In some embodiments, the microfluidic mixer comprises at least two dual-channel mixing units connected in series, one of which is the mixing unit. In some embodiments, the microfluidic mixer comprises at least two of the mixing units connected in series; or comprises at least one of the mixing units and one DVBM mixing unit connected in series.

[0012] In some embodiments, the two channels are of the same length.

[0013] In some embodiments, the two channels are symmetrically arranged. Preferably, the two channels are symmetrically arranged relative to the center of the mixing unit, or the two channels are symmetrically arranged relative to the central axis of the mixing unit.

[0014] In some embodiments, the two channels are arranged symmetrically with respect to a line connecting the inlet end and the outlet end of the mixing unit.

[0015] In some embodiments, the two channels are located in the same plane or in different planes.

[0016] In some embodiments, the two channels are arranged in a racetrack shape or a fan shape.

[0017] In some embodiments, the two side walls are respectively a first side wall and a second side wall, and both the first side wall and the second side wall are composed of an arc-shaped first side wall segment and a straight-line second side wall segment.

[0018] In some embodiments, the two channels are respectively a first channel and a second channel; the first side wall section of the first channel is connected to the inlet end, and the second side wall section of the second channel is connected to the inlet end; the second side wall section of the first channel is connected to the outlet end, and the first side wall section of the second channel is connected to the outlet end; or,

[0019] The second side wall section of the first channel is connected to the inlet end, the second side wall section of the second channel is connected to the inlet end, the first side wall section of the first channel is connected to the outlet end, and the first side wall section of the second channel is connected to the outlet end.

[0020] In some embodiments, the first sidewall segment of the second sidewall of the first channel and the second sidewall segment of the second sidewall of the second channel intersect at the inlet to form a second corner; the second sidewall segment of the second sidewall of the first channel and the first sidewall segment of the second sidewall of the second channel intersect at the outlet to form a third corner; or

[0021] The second side wall section of the second side wall of the first channel intersects with the second side wall section of the second side wall of the second channel at the inlet to form a fourth corner; the first side wall section of the second side wall of the first channel intersects with the first side wall section of the second side wall of the second channel at the outlet to form an arc.

[0022] In some embodiments, the second corner, the third corner, and the fourth corner are arc-shaped corners.

[0023] In some embodiments, the adjacent side walls of the two channels are connected to form an island; preferably, the island is rectangular or fan-shaped.

[0024] In some embodiments, the microfluidic mixer further comprises at least two liquid inlet channels, and the at least two liquid inlet channels are both connected to the inlet end of the mixing unit.

[0025] In some embodiments, the at least two liquid inlet channels include a first liquid inlet channel, a second liquid inlet channel and a third liquid inlet channel; the inlet of the first liquid inlet channel and the inlet of the third liquid inlet channel are configured to be connected to a first solution providing device, and the outlet of the first liquid inlet channel and the outlet of the third liquid inlet channel are both connected to the inlet end of the mixing unit; the inlet of the second liquid inlet channel is configured to be connected to a second solution providing device, and the outlet of the second liquid inlet channel is connected to the inlet end of the mixing unit.

[0026] In some embodiments, each of the two channels includes a first channel segment and a second channel segment, and a first corner is formed at a connection between the first channel segment and the second channel segment.

[0027] In some embodiments, one of the first channel segment and the second channel segment is an arc-shaped channel, and the other of the first channel segment and the second channel segment is a straight channel.

[0028] In some embodiments, the width of the first channel section and / or the second channel section is consistent along the fluid flow direction from the inlet end to the outlet end.

[0029] In some embodiments, the two channels are respectively a first channel and a second channel;

[0030] The first channel section of the first channel is connected to the inlet end, and the second channel section of the second channel is connected to the inlet end; the second channel section of the first channel is connected to the outlet end, and the first channel section of the second channel is connected to the outlet end; or

[0031] The second channel section of the first channel is connected to the inlet end, and the second channel section of the second channel is connected to the inlet end;

[0032] The first channel section of the first channel is connected to the outlet end, and the first channel section of the second channel is connected to the outlet end.

[0033] In one aspect of the present disclosure, a microfluidic mixer is provided, which includes a mixing unit, wherein the mixing unit includes an inlet end, an outlet end and two channels, the inlets of the two channels are both connected to the inlet end, the outlets of the two channels are both connected to the outlet end, and the impedance of the two channels is the same.

[0034] In some embodiments, each of the two channels includes a first channel segment and a second channel segment, and a first corner is formed at a connection between the first channel segment and the second channel segment.

[0035] In some embodiments, one of the first channel segment and the second channel segment is an arc-shaped channel, and the other of the first channel segment and the second channel segment is a straight channel.

[0036] In some embodiments, the width of the first channel section and / or the second channel section is consistent along the fluid flow direction from the inlet end to the outlet end.

[0037] In some embodiments, the two channels are respectively a first channel and a second channel;

[0038] The first channel section of the first channel is connected to the inlet end, and the second channel section of the second channel is connected to the inlet end; the second channel section of the first channel is connected to the outlet end, and the first channel section of the second channel is connected to the outlet end; or

[0039] The second channel section of the first channel is connected to the inlet end, and the second channel section of the second channel is connected to the inlet end;

[0040] The first channel section of the first channel is connected to the outlet end, and the first channel section of the second channel is connected to the outlet end.

[0041] In some embodiments, the two channels are arranged in a racetrack shape or a fan shape.

[0042] In some embodiments, the inlet end and the outlet end are aligned along a straight line.

[0043] In some embodiments, the angle between the axis of the inlet end and the axis of the outlet end is 180 degrees.

[0044] In some embodiments, the width or height of each of the two channels ranges from 20 um to 5 mm.

[0045] In some embodiments, the microfluidic mixer comprises at least two of the mixing units connected in series; or, comprises at least one of the mixing units and one DVBM mixing unit connected in series.

[0046] In some embodiments, the outlet ends and the inlet ends of the plurality of mixing units are aligned in a straight line with each other.

[0047] In some embodiments, the angle between the axis of each outlet end and the axis of each inlet end of the plurality of mixing units is 180 degrees.

[0048] In some embodiments, the two channels are of the same length.

[0049] In some embodiments, the two channels are arranged symmetrically with respect to the center of the mixing unit, or the two channels are arranged symmetrically with respect to the central axis of the mixing unit.

[0050] In some embodiments, the two channels are arranged symmetrically with respect to a line connecting the inlet end and the outlet end of the mixing unit.

[0051] In some embodiments, adjacent side walls of the two channels of the mixing unit are connected to form an island, and the shape of the island includes a quasi-rectangular or fan-shaped shape.

[0052] In some embodiments, the microfluidic mixer comprises at least two of the mixing units connected in series.

[0053] In another aspect of the present disclosure, a microfluidic chip is provided, which is obtained by encapsulating the above-mentioned microfluidic mixer.

[0054] Based on the above technical solution, the present disclosure has at least the following beneficial effects:

[0055] In some embodiments, the inlets of the two channels of the mixing unit are connected to the inlet end, and the outlets of the two channels are connected to the outlet end. The internal channel structure of the mixing unit adopts a bifurcated-mixing structural design, so that different fluids collide violently and mix during the bifurcated-mixing process, thereby improving the mixing efficiency. When the solution passes through the first arc-shaped side wall section, it can generate Dean vortexes, and when passing through the first corner, it can generate turbulence. The combination of the bifurcated-mixing structure, Dean vortexes and turbulence can enhance mixing and improve mixing efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0056] The drawings described herein are used to provide a further understanding of the present disclosure and constitute a part of this application. The illustrative embodiments of the present disclosure and their descriptions are used to explain the present disclosure and do not constitute an improper limitation of the present disclosure. In the drawings:

[0057] FIG1 is a schematic diagram of a microfluidic mixer structure provided by a first embodiment of the present disclosure;

[0058] FIG2 is a schematic diagram of a mixing unit provided in a first embodiment of the present disclosure;

[0059] FIG3 is a schematic diagram of a microfluidic mixer structure with dual-channel inlets provided in some embodiments of the present disclosure;

[0060] FIG4 is a schematic diagram of a microfluidic mixer structure with three channel inlets provided in some embodiments of the present disclosure;

[0061] FIG5 is a schematic diagram of comparative design structures of microfluidic mixers in some related arts;

[0062] FIG6 is a schematic diagram showing a comparison of the particle size and PDI of nucleic acid nanoparticles prepared by microfluidic mixers (small-scale, pilot, and scale-up) provided in some embodiments of the present disclosure and a comparative design of microfluidic mixers at different flow rates;

[0063] FIG7 is a schematic diagram showing a comparison of the encapsulation efficiency of nucleic acid nanoparticles prepared by a microfluidic mixer and a comparative microfluidic mixer design at different flow rates provided by some embodiments of the present disclosure;

[0064] FIG8 is a schematic diagram showing a comparison of particle size and PDI of nucleic acid nanoparticles prepared on a large scale (above pilot scale) using a stainless steel microfluidic mixer according to some embodiments of the present disclosure;

[0065] FIG9 is a schematic diagram showing a comparison of the encapsulation efficiency of nucleic acid nanoparticles prepared on a large scale (above pilot scale) using a stainless steel microfluidic mixer according to some embodiments of the present disclosure at different flow rates;

[0066] FIG10 is a schematic diagram showing a comparison of particle size and PDI of nucleic acid nanoparticles prepared using two microfluidic mixers with different numbers of inlet channels provided in some embodiments of the present disclosure;

[0067] FIG11 is a schematic diagram showing a comparison of the encapsulation efficiency of nucleic acid nanoparticles prepared using two microfluidic mixers with different numbers of inlet channels according to some embodiments of the present disclosure;

[0068] FIG12 is a schematic diagram of the microfluidic mixer shown in FIG5 compared with the microfluidic mixer designed under a fluorescence microscope in a state where two liquids are mixed;

[0069] FIG13 is a schematic diagram comparing the mixing efficiency of a microfluidic mixer provided by some embodiments of the present disclosure and a microfluidic mixer of a comparative design;

[0070] 14a to 14e are schematic diagrams of five angle forms of some microfluidic mixers provided by the present disclosure;

[0071] FIG14f is a schematic diagram showing comparative designs of microfluidic mixers in some related arts;

[0072] FIG15 is a schematic diagram of a microfluidic mixer structure provided in a second embodiment of the present disclosure;

[0073] FIG16 is a schematic diagram of a mixing unit provided in a second embodiment of the present disclosure;

[0074] FIG17 is a schematic diagram of a mixing unit provided in the first embodiment of the present disclosure;

[0075] FIG18 is a schematic diagram of a mixing unit provided in a second embodiment of the present disclosure;

[0076] FIG19 is a schematic diagram of a microfluidic mixer structure provided in a third embodiment of the present disclosure;

[0077] FIG20 is a schematic diagram of a microfluidic mixer structure provided in a fourth embodiment of the present disclosure;

[0078] FIG21 is a schematic diagram of a microfluidic mixer structure provided in the fifth embodiment of the present disclosure.

[0079] The numbers in the accompanying drawings are explained as follows: 10-mixing unit; 20-liquid inlet channel; 201-first liquid inlet channel; 202-second liquid inlet channel; 203-third liquid inlet channel; 204-first liquid injection port; 205-second liquid injection port; 1-inlet end; 2-outlet end; 3-channel; 3a-first channel; 3b-second channel; 31-side wall; 311-first side wall; 312-second side wall; 301-first side wall section; 301a-first side wall section of the first side wall; 301b-first side wall section of the second side wall; 302-second side wall section; 302a-second side wall section of the first side wall; 302b-second side wall section of the second side wall; 321-first corner; 322-second corner; 323-third corner; 324-fourth corner; 31a-first channel section; 31b-second channel section.

[0080] It should be understood that the size of each part shown in the drawings is not drawn according to the actual proportional relationship.In addition, the same or similar reference numerals represent the same or similar components. DETAILED DESCRIPTION

[0081] Various exemplary embodiments of the present disclosure will now be described in detail with reference to the accompanying drawings. The description of the exemplary embodiments is merely illustrative and is in no way intended to limit the present disclosure, its application, or use. The present disclosure can be implemented in many different forms and is not limited to the embodiments described herein. These embodiments are provided to make the present disclosure thorough and complete and to fully convey the scope of the present disclosure to those skilled in the art. It should be noted that unless otherwise specifically stated, the relative arrangement of parts and steps, the composition of materials, numerical expressions, and numerical values ​​set forth in these embodiments should be interpreted as being merely exemplary and not as limiting.

[0082] As used in this disclosure, the terms "first," "second," and similar terms do not denote any order, quantity, or importance, but are merely used to distinguish one part from another. Terms such as "include" or "comprise" mean that the elements preceding the term encompass the elements listed after the term, and do not exclude the possibility of also encompassing other elements. Terms such as "upper," "lower," "left," and "right" are used only to indicate relative positional relationships. When the absolute position of the object being described changes, the relative positional relationship may also change accordingly.

[0083] In the present disclosure, when a specific device is described as being located between a first device and a second device, an intervening device may or may not be present between the specific device and the first device or the second device. When a specific device is described as being connected to another device, the specific device may be directly connected to the other device without an intervening device, or may be not directly connected to the other device but with an intervening device.

[0084] All terms (including technical or scientific terms) used in this disclosure have the same meaning as those understood by one of ordinary skill in the art to which this disclosure belongs, unless otherwise specifically defined. It should also be understood that terms defined in, for example, general dictionaries should be interpreted as having a meaning consistent with their meaning in the context of the relevant technology, and should not be interpreted in an idealized or highly formal sense, unless explicitly defined herein.

[0085] Technologies, methods, and equipment known to ordinary technicians in the relevant art may not be discussed in detail, but where appropriate, the technologies, methods, and equipment should be considered part of the specification.

[0086] 1-2 and 15 - 16 , an embodiment of the present disclosure provides a microfluidic mixer including a mixing unit 10 .

[0087] The mixing unit 10 includes an inlet end 1 , an outlet end 2 and two channels 3 . The inlets of the two channels 3 are both connected to the inlet end 1 , and the outlets of the two channels 3 are both connected to the outlet end 2 .

[0088] At least one of the two channels 3 is configured to cause the solution flowing therein to form Dean vortices and turbulence.

[0089] In the above embodiment, the inlets of the two channels 3 of the mixing unit 10 are both connected to the inlet end 1, and the outlets of the two channels 3 are both connected to the outlet end 2. The internal channel structure of the mixing unit 10 adopts a bifurcating-mixing structure design, which causes different fluids to violently collide and mix during the bifurcating-mixing process, thereby improving mixing efficiency. In addition, at least one channel 3 of the mixing unit 10 is configured so that the solution flowing therein forms Dean vortices and turbulence, thereby improving mixing efficiency.

[0090] In some embodiments, in a cross section taken along the fluid flow direction, at least one of the two channels 3 includes two sidewalls 31, and at least one of the two sidewalls 31 includes a first sidewall segment 301 and a second sidewall segment 302. The first sidewall segment 301 and the second sidewall segment 302 have different centers of curvature. The first sidewall segment 301 is an arcuate segment, and the first sidewall segment 301 and the second sidewall segment 302 intersect to form a first corner 321.

[0091] In the above embodiment, the two side wall segments with different centers of curvature can form a corner on the side wall at the intersection of the two side wall segments, and the corner collides with the solution, causing the solution to generate turbulence, and the two side wall segments with different centers of curvature include at least one arc segment. Due to the curvature effect of the arc segment, the solution generates Dean vortex. Therefore, the solution flowing in the channel 3 can form Dean vortex and turbulence, thereby improving the mixing efficiency.

[0092] 2 and 16 , in some embodiments, the first sidewall segment 301 is an arc segment, the second sidewall segment 302 is a straight segment, and the first sidewall segment 301 and the second sidewall segment 302 intersect to form a first corner 321 .

[0093] In the above embodiment, the solution can generate Dean vortices when passing through the first sidewall section 301 and can generate turbulence when passing through the first corner 321. The combination of Dean vortices and turbulence can deepen mixing and improve mixing efficiency.

[0094] 2 and 16 , in some embodiments, the first corner portion 321 is a curved corner portion.

[0095] In the above embodiment, the first corner portion 321 is an arc-shaped corner, which can avoid the generation of a cleaning dead corner at the first corner portion 321 and facilitate online cleaning.

[0096] 2 and 16 , in some embodiments, the first sidewall segment 301 and the second sidewall segment 302 are asymmetrically arranged.

[0097] In some embodiments, the first sidewall segment 301 and the second sidewall segment 302 both extend smoothly from the inlet end 1 to the outlet end 2 .

[0098] The first side wall section 301 and the second side wall section 302 are smooth side wall sections, which facilitate guiding the solution from the inlet end 1 to the outlet end 2 .

[0099] In some embodiments, the sidewall 31 is composed of two sidewall sections: a first sidewall section 301 and a second sidewall section 302 .

[0100] 1 and 15 , in some embodiments, the microfluidic mixer includes at least two mixing units 10 , and the outlet end 2 of the upstream mixing unit 10 is connected to the inlet end 1 of the downstream mixing unit 10 .

[0101] In the above embodiment, the microfluidic mixer may include one mixing unit 10 or may include two or more mixing units 10 connected in series, which can be selected according to mixing needs so that the solution can be fully mixed in the mixing unit 10.

[0102] In some embodiments, the microfluidic mixer includes at least one mixing unit 10 and a DVBM mixing unit connected in series. The DVBM mixing unit is a comparative design of the mixing unit in the related art.

[0103] In some embodiments, two adjacent mixing units 10 may be in the same horizontal position or not. If two adjacent mixing units 10 are in the same horizontal position, processing is convenient. If two adjacent mixing units 10 are not in the same horizontal position, laminar flow can be changed to further improve mixing efficiency.

[0104] In some embodiments, the two channels 3 have the same length.

[0105] In the above embodiment, the path lengths of the two channels 3 within the mixing unit 10 may be the same or different. Preferably, the path lengths of the two channels 3 are consistent, so that the average velocity of the separated fluids can be consistent, and the separated fluids can always be mixed at the set ratio and rate within the microscopic unit, further improving the mixing speed and mixing efficiency per unit time, and ensuring stable and rapid production of nucleic acid nanoparticles.

[0106] In some embodiments, the two channels 3 are symmetrically arranged.

[0107] In the above embodiment, the two channels 3 can be arranged asymmetrically or symmetrically, preferably symmetrically. The symmetrical arrangement of the two channels 3 can maintain a consistent average velocity of the separated fluids, ensuring that the separated fluids are always mixed at the set ratio and rate within the microscopic unit, further improving the mixing speed and mixing efficiency per unit time, and ensuring stable and rapid production of nucleic acid nanoparticles.

[0108] In some embodiments, the two channels 3 are arranged symmetrically to each other with respect to the center of the mixing unit 10 .

[0109] In some embodiments, the two channels 3 are arranged symmetrically with respect to the central axis of the mixing unit 10 .

[0110] In some embodiments, the two channels 3 are arranged symmetrically with respect to a line connecting the inlet end 1 and the outlet end 2 of the mixing unit 10 .

[0111] In some embodiments, the two channels 3 are located in the same plane or in different planes.

[0112] In the above embodiment, the two channels 3 can be located in the same plane or in different planes. The two channels 3 can be located in the same plane for easy processing, while the two channels 3 can be located in different planes to change the laminar flow phenomenon and further improve the mixing efficiency.

[0113] In some embodiments, both channels 3 include two side walls 31 , and at least one of the two side walls 31 of each channel 3 includes two side wall segments with different centers of curvature.

[0114] In the above embodiment, the two channels 3 can both cause the solutions flowing therein to form Dean vortices and turbulence, thereby improving the mixing efficiency.

[0115] In some embodiments, the two channels 3 are arranged in a racetrack shape or a fan shape.

[0116] 2 and 16 , in some embodiments, the two sidewalls 31 are respectively a first sidewall 311 and a second sidewall 312 , and the first sidewall 311 and the second sidewall 312 each include a first sidewall segment 301 and a second sidewall segment 302 having different centers of curvature.

[0117] In the above embodiment, the first side wall 311 and the second side wall 312 both include two side wall segments with different centers of curvature, which is beneficial for the solution flowing in the channel 3 to form Dean vortices and turbulence, thereby improving mixing efficiency.

[0118] In some embodiments, the first sidewall 311 and the second sidewall 312 are both composed of an arc-shaped first sidewall segment 301 and a straight-line second sidewall segment 302 .

[0119] In some embodiments, the first sidewall segment 301 is an arc segment, the second sidewall segment 302 is a straight segment, and the intersection of the arc segment and the straight segment forms a first corner 321 .

[0120] In some embodiments, both channels 3 include two side walls 31 , and both side walls 31 include a first side wall segment 301 and a second side wall segment 302 with different centers of curvature.

[0121] 2 , 16 , 17 and 18 , in some embodiments, the two channels 3 are respectively a first channel 3 a and a second channel 3 b .

[0122] 2 and 17 , in the first embodiment of the mixing unit 10 , the first sidewall segments 301 of the two sidewalls 31 of the first channel 3 a are connected to the inlet end 1 , and the second sidewall segments 302 of the two sidewalls 31 of the first channel 3 a are connected to the outlet end 2 ;

[0123] The first side wall sections 301 of the two side walls 31 of the second channel 3 b are connected to the outlet end 2 , and the second side wall sections 302 of the two side walls 31 of the second channel 3 b are connected to the inlet end 1 .

[0124] 16 and 18 , in the second embodiment of the mixing unit 10 , the second sidewall segments 302 of the two sidewalls 31 of the first channel 3 a are connected to the inlet end 1 , and the first sidewall segments 301 of the two sidewalls 31 of the first channel 3 a are connected to the outlet end 2 ;

[0125] The second side wall sections 302 of the two side walls 31 of the second channel 3 b are connected to the inlet end 1 ; the first side wall sections 301 of the two side walls 31 of the second channel 3 b are connected to the outlet end 2 .

[0126] 2 , 16 , 17 and 18 , in some embodiments, the first channel 3a and the second channel 3b both include a first side wall 311 and a second side wall 312, the second side wall 312 of the first channel 3a is adjacent to the second side wall 312 of the second channel 3b, and the two ends of the two second side walls 312 are respectively connected to each other at the inlet and the outlet.

[0127] The first sidewall section 301 includes a first sidewall section 301 a of a first sidewall 311 and a first sidewall section 301 b of a second sidewall 312 .

[0128] The second sidewall segment 302 includes a second sidewall segment 302 a of the first sidewall 311 and a second sidewall segment 302 b of the second sidewall 312 .

[0129] 2 and 17 , in the first embodiment, the first sidewall segment 301 is an arcuate segment. The second sidewall segment 302 is a straight segment. The first sidewall segment 301b of the second sidewall 312 of the first channel 3a intersects with the second sidewall segment 302b of the second sidewall 312 of the second channel 3b at the inlet, forming a second corner 322. The second sidewall segment 302b of the second sidewall 312 of the first channel 3a intersects with the first sidewall segment 301b of the second sidewall 312 of the second channel 3b at the outlet, forming a third corner 323.

[0130] 16 and 18 , in the second embodiment, the first sidewall segment 301 is an arcuate segment, and the second sidewall segment 302 is a straight segment. The second sidewall segment 302b of the second sidewall 312 of the first channel 3a intersects with the second sidewall segment 302b of the second sidewall 312 of the second channel 3b at the inlet, forming a fourth corner 324. The first sidewall segment 301b of the second sidewall 312 of the first channel 3a intersects with the first sidewall segment 301b of the second sidewall 312 of the second channel 3b at the outlet, forming an arc.

[0131] In some embodiments, the second corner 322, the third corner 323, and the fourth corner 324 are all arc-shaped corners. The arc-shaped corners can avoid the generation of cleaning dead corners at the second corner 322, the third corner 323, and the fourth corner 324, thereby facilitating online cleaning.

[0132] In some embodiments, adjacent side walls of two channels 3 are connected to form an island. Optionally, the shape of the island includes a quasi-rectangular shape (see FIG2 ) or a fan shape (see FIG16 ).

[0133] In the embodiments shown in Figures 2 and 16, the second side walls 312 of the two channels 3 are adjacent to each other, one end of the second side walls 312 of the two channels 3 intersects at the inlet, and the other end of the second side walls 312 of the two channels 3 intersects at the outlet, forming an annular structure called a "ring island".

[0134] The microfluidic mixer provided in the embodiments of the present disclosure can be used to mix multiple liquids, such as mixing two liquids, mixing three liquids, mixing four liquids or more. Multiple liquids enter the microfluidic mixer through the mixing channel inlet.

[0135] 3 and 4 , in some embodiments, the microfluidic mixer further includes at least two liquid inlet channels 20 , and the at least two liquid inlet channels 20 are both connected to the inlet end 1 of the mixing unit 10 .

[0136] In the above embodiment, the microfluidic mixer can mix at least two solutions.

[0137] 3 , in some embodiments, the at least two liquid inlet channels 20 include a first liquid inlet channel 201 and a second liquid inlet channel 202 .

[0138] The inlet of the first liquid inlet channel 201 is configured to communicate with the first solution providing device, and the outlet of the first liquid inlet channel 201 is communicated with the inlet end 1 of the mixing unit 10 .

[0139] The inlet of the second liquid inlet channel 202 is configured to communicate with the second solution providing device, and the outlet of the second liquid inlet channel 202 is communicated with the inlet end 1 of the mixing unit 10 .

[0140] In the above embodiment, the microfluidic mixer is a dual-inlet channel chip, forming a Y-shape, capable of mixing at least two solutions. One solution enters through the first inlet channel 201, and the other enters through the second inlet channel 202. The two solutions merge at the inlet end 1 of the mixing unit 10. The merged solutions then enter the two channels 3 of the mixing unit 10, merge again at the outlets of the two channels 3, and enter the outlet end 2 of the mixing unit 10.

[0141] 4 , in some embodiments, the at least two liquid inlet channels 20 include a first liquid inlet channel 201 , a second liquid inlet channel 202 , and a third liquid inlet channel 203 ;

[0142] The inlet of the first liquid inlet channel 201 and the inlet of the third liquid inlet channel 203 are configured to be connected to the first solution providing device, and the outlet of the first liquid inlet channel 201 and the outlet of the third liquid inlet channel 203 are connected to the inlet end 1 of the mixing unit 10;

[0143] The inlet of the second liquid inlet channel 202 is configured to communicate with the second solution providing device, and the outlet of the second liquid inlet channel 202 is communicated with the inlet end 1 of the mixing unit 10 .

[0144] In the above embodiment, the microfluidic mixer is a three-inlet channel chip capable of mixing at least two solutions. The first inlet channel 201, the second inlet channel 202, the third inlet channel 203, and the inlet end of the mixing unit 10 form a "cross" structure. One solution enters through the first and third inlet channels 201 and 203, while the other enters through the second inlet channel 202. The two solutions then merge at the inlet end 1 of the mixing unit 10. The merged solutions then enter the two channels 3 of the mixing unit 10, merge again at the outlets of the two channels 3, and enter the outlet end 2 of the mixing unit 10.

[0145] The internal channel structure of the mixing unit 10 adopts the above-mentioned bifurcating-mixing structural design, so that different fluids collide violently and mix during the bifurcating-mixing process, thereby improving the mixing efficiency.

[0146] 4 , the inlet of the first liquid inlet channel 201 and the inlet of the third liquid inlet channel 203 are connected to the first liquid injection port 204 , and the first liquid injection port 204 is communicated with the first solution providing device.

[0147] The inlet of the second liquid inlet channel 202 is connected to the second liquid injection port 205, and the second liquid injection port 205 is communicated with the second solution providing device.

[0148] 17 and 18 , in some embodiments, each of the two channels 3 includes a first channel segment 31 a and a second channel segment 31 b , and a first corner portion 321 is formed at a connection between the first channel segment 31 a and the second channel segment 31 b .

[0149] In some embodiments, one of the first channel segment 31a and the second channel segment 31b is an arc-shaped channel, and the other of the first channel segment 31a and the second channel segment 31b is a linear channel.

[0150] In some embodiments, the width of the first channel section 31 a and / or the second channel section 31 b is uniform along the fluid flow direction from the inlet end 1 to the outlet end 2 .

[0151] In some embodiments, the height of the first channel section 31 a and / or the second channel section 31 b is consistent along the fluid flow direction from the inlet end 1 to the outlet end 2 .

[0152] In some embodiments, the two channels 3 are respectively a first channel 3 a and a second channel 3 b .

[0153] 17 , in the first embodiment of the mixing unit 10 , the first channel section 31 a of the first channel 3 a is connected to the inlet end 1 , and the second channel section 31 b of the second channel 3 b is connected to the inlet end 1 ;

[0154] The second channel section 31 b of the first channel 3 a is connected to the outlet end 2 , and the first channel section 31 a of the second channel 3 b is connected to the outlet end 2 .

[0155] 18 , in the second embodiment of the mixing unit 10 , the second channel section 31 b of the first channel 3 a is connected to the inlet end 1 , and the second channel section 31 b of the second channel 3 b is connected to the inlet end 1 ;

[0156] The first channel section 31 a of the first channel 3 a is connected to the outlet end 2 , and the first channel section 31 a of the second channel 3 b is connected to the outlet end 2 .

[0157] 1-2 and 15-16 , some embodiments of the present disclosure provide a microfluidic mixer, which includes a mixing unit 10, the mixing unit 10 including an inlet end 1, an outlet end 2 and two channels 3, the inlets of the two channels 3 are both connected to the inlet end 1, the outlets of the two channels 3 are both connected to the outlet end 2, and the impedance of the two channels 3 is the same.

[0158] 17 and 18 , in some embodiments, each of the two channels 3 includes a first channel segment 31 a and a second channel segment 31 b , and a first corner portion 321 is formed at a connection between the first channel segment 31 a and the second channel segment 31 b .

[0159] In some embodiments, one of the first channel segment 31a and the second channel segment 31b is an arc-shaped channel, and the other of the first channel segment 31a and the second channel segment 31b is a linear channel.

[0160] In some embodiments, the width of the first channel section 31 a and / or the second channel section 31 b is uniform along the fluid flow direction from the inlet end 1 to the outlet end 2 .

[0161] In some embodiments, the two channels 3 are respectively a first channel 3 a and a second channel 3 b .

[0162] 17 , in the first embodiment of the mixing unit 10 , the first channel section 31 a of the first channel 3 a is connected to the inlet end 1 , and the second channel section 31 b of the second channel 3 b is connected to the inlet end 1 ;

[0163] The second channel section 31 b of the first channel 3 a is connected to the outlet end 2 , and the first channel section 31 a of the second channel 3 b is connected to the outlet end 2 .

[0164] 18 , in the second embodiment of the mixing unit 10 , the second channel section 31 b of the first channel 3 a is connected to the inlet end 1 , and the second channel section 31 b of the second channel 3 b is connected to the inlet end 1 ;

[0165] The first channel section 31 a of the first channel 3 a is connected to the outlet end 2 , and the first channel section 31 a of the second channel 3 b is connected to the outlet end 2 .

[0166] In some embodiments, the two channels 3 are arranged in a racetrack shape or a fan shape.

[0167] In some embodiments, the inlet end 1 and the outlet end 2 are aligned along a straight line.

[0168] In some embodiments, the angle between the axis of the inlet end 1 and the axis of the outlet end 2 is 180 degrees.

[0169] In some embodiments, the width or height of each of the two channels 3 ranges from 20 μm to 5 mm.

[0170] In some embodiments, the width or height of each of the two channels 3 ranges from 50 μm to 2 mm.

[0171] In some embodiments, at least two mixing units 10 are connected in series; or, at least one mixing unit 10 and one DVBM mixing unit are connected in series.

[0172] In some embodiments, the outlet ends 2 and the inlet ends 1 of the plurality of mixing units 10 are aligned in a straight line.

[0173] In some embodiments, the angle between the axis of each outlet end 2 and the axis of each inlet end 1 of the plurality of mixing units 10 is 180 degrees.

[0174] In some embodiments, the two channels 3 have the same length.

[0175] In some embodiments, the two channels 3 are arranged symmetrically to each other with respect to the center of the mixing unit 10 .

[0176] In some embodiments, the two channels 3 are arranged symmetrically with respect to a line connecting the inlet end 1 and the outlet end 2 of the mixing unit 10 .

[0177] In some embodiments, adjacent side walls of two channels 3 of the mixing unit 10 are connected to form an island, and the shape of the island includes a quasi-rectangular shape or a fan shape.

[0178] In some embodiments, the microfluidic mixer includes at least two mixing units 10 connected in series, and two adjacent mixing units 10 are symmetrically arranged.

[0179] In some embodiments, the microfluidic mixer includes at least two mixing units 10 connected in series, and two adjacent mixing units 10 are arranged in sequence.

[0180] Some embodiments of the present disclosure further provide a microfluidic chip, which is obtained by encapsulating the microfluidic mixer in any of the above embodiments.

[0181] Various specific embodiments of the microfluidic mixer are described in detail below.

[0182] 1 and 2 , in a first embodiment of a mixing unit 10 , the mixing unit 10 includes an inlet port 1, an outlet port 2, a first channel 3a, and a second channel 3b. The first channel 3a and the second channel 3b are symmetrically arranged. Each of the first channel 3a and the second channel 3b includes two sidewalls 31 , namely a first sidewall 311 and a second sidewall 312 . Each of the sidewalls 31 includes a first sidewall segment 301 and a second sidewall segment 302 . The first sidewall segment 301 is an arcuate segment, while the second sidewall segment 302 is a straight segment. The first sidewall segments 301 of the two sidewalls 31 of the first channel 3a are connected to the inlet port 1, the second sidewall segments 302 of the two sidewalls 31 of the first channel 3a are connected to the outlet port 2, the second sidewall segments 302 of the two sidewalls 31 of the second channel 3b are connected to the inlet port 1, and the first sidewall segments 301 of the two sidewalls 31 of the second channel 3b are connected to the outlet port 2.

[0183] The second sidewall 312 of the first channel 3a is adjacent to the second sidewall 312 of the second channel 3b, and one end of the two second sidewalls 312 intersects at the entrance, and the other ends of the two second sidewalls 312 intersect at the exit. The first sidewall segment 301b of the second sidewall 312 of the first channel 3a intersects the second sidewall segment 302b of the second sidewall 312 of the second channel 3b at the entrance, forming a second corner 322. The second sidewall segment 302b of the second sidewall 312 of the first channel 3a intersects the first sidewall segment 301b of the second sidewall 312 of the second channel 3b at the exit, forming a third corner 323.

[0184] In the first embodiment of the mixing unit 10, the first channel 3a and the second channel 3b form a structure similar to a rectangle.

[0185] Referring to Figure 1 , in a first embodiment of the microfluidic mixer, two mixing units 10 provided in the first embodiment are arranged in a mirror-image arrangement, with the second sidewall segments 302, i.e., the straight segments, of the two adjacent mixing units 10 forming a certain angle α. Optionally, the angle α between the straight segments of the two adjacent mixing units 10 ranges from 30° to 180°, preferably from 50° to 160°, more preferably from 70° to 140°, and even more preferably from 80° to 130°.

[0186] According to the description of the above embodiments, the shape of the mixing unit 10 provided in the first embodiment can be a quasi-rectangular shape containing a quasi-rectangular internal island.

[0187] Each mixing unit 10 has an island inside, and the size of the island increases accordingly with the size of the channel. Each mixing unit 10 is arranged in a mirror-symmetrical form at a certain angle and connected in series, and the last mixing unit 10 has an outlet channel.

[0188] Referring to Figures 15 and 16, in a second embodiment of the mixing unit 10, the mixing unit 10 includes an inlet port 1, an outlet port 2, a first channel 3a, and a second channel 3b. The first channel 3a and the second channel 3b are symmetrically arranged. The first channel 3a and the second channel 3b each include two sidewalls 31, namely a first sidewall 311 and a second sidewall 312. Both sidewalls 31 include a first sidewall segment 301 and a second sidewall segment 302, wherein the first sidewall segment 301 is an arcuate segment and the second sidewall segment 302 is a straight segment. The second sidewall segments 302 of the two sidewalls 31 of the first channel 3a are connected to the inlet port 1, the first sidewall segments 301 of the two sidewalls 31 of the first channel 3a are connected to the outlet port 2, the second sidewall segments 302 of the two sidewalls 31 of the second channel 3b are connected to the inlet port 1, and the first sidewall segments 301 of the two sidewalls 31 of the second channel 3b are connected to the outlet port 2.

[0189] The second sidewall 312 of the first channel 3a is adjacent to the second sidewall 312 of the second channel 3b, and one end of the two second sidewalls 312 intersects at the entrance, and the other end of the two second sidewalls 312 intersects at the exit. The second sidewall segment 302b of the second sidewall 312 of the first channel 3a intersects the second sidewall segment 302b of the second sidewall 312 of the second channel 3b at the entrance, forming a fourth corner 324. The first sidewall segment 301b of the second sidewall 312 of the first channel 3a intersects the first sidewall segment 301b of the second sidewall 312 of the second channel 3b at the exit, forming an arc.

[0190] In the second embodiment of the mixing unit 10, the first channel 3a and the second channel 3b form a fan-like structure.

[0191] 15 , in the second embodiment of the microfluidic mixer, two mixing units 10 provided in the second embodiment are arranged in sequence.

[0192] According to the description of the above embodiments, the shape of the mixing unit 10 provided in the second embodiment can be a fan-shaped shape containing a fan-shaped internal island.

[0193] There is an island inside each mixing unit 10, and the size of the island increases accordingly as the channel size increases. Each mixing unit 10 is arranged in sequence and connected in series, and the last mixing unit 10 has an outlet channel.

[0194] To more clearly distinguish the mixing unit 10 provided in the first embodiment from the mixing unit 10 provided in the second embodiment, the mixing unit 10 provided in the first embodiment is labeled as mixing unit 10a, and the mixing unit 10 provided in the second embodiment is labeled as mixing unit 10b.

[0195] 19 , in a third embodiment of the microfluidic mixer, the microfluidic mixer includes the mixing unit 10 a provided in the first embodiment and the mixing unit 10 b provided in the second embodiment, and the mixing units 10 a provided in the first embodiment and the mixing units 10 b provided in the second embodiment are arranged alternately in sequence.

[0196] 20 , in a fourth embodiment of a microfluidic mixer, the microfluidic mixer includes the mixing unit 10 b provided in the second embodiment and a DVBM mixing unit. The mixing unit 10 b and the DVBM mixing unit provided in the second embodiment are alternately arranged.

[0197] 21 , in a fifth embodiment of a microfluidic mixer, the microfluidic mixer includes the mixing unit 10 a provided in the first embodiment and a DVBM mixing unit. The mixing unit 10 a and the DVBM mixing unit provided in the first embodiment are alternately arranged in sequence.

[0198] In some embodiments, the microfluidic mixer can be combined with known fluidic elements, such as inlets, outlets, syringes, pumps, detectors, or other mixers. The microfluidic mixer can also be fixed on a base.

[0199] The microfluidic mixer provided by the embodiments of the present disclosure has a simple structural design, and the chip channels are easily magnified exponentially, suitable for linear amplification production, easy for industrial manufacturing, and suitable for mass production of nanoformulations, which can meet the growing demand for nucleic acid preparations.

[0200] The chip provided in the embodiment of the present disclosure adopts a mixing method that combines Dean vortex and turbulent flow, which has high mixing efficiency, is less affected by flow rate, and the encapsulation rate does not decrease with the increase of flow rate or scale.

[0201] The microfluidic mixer provided in the embodiments of the present disclosure can quickly and efficiently mix liquid microfluids and can be used for rapid mixing of multiple liquids or for manufacturing nanoparticles, such as lipid nanoparticles or PLGA (poly(lactic-co-glycolic acid)) nanoparticles.

[0202] Some embodiments of the present disclosure further provide a microfluidic chip, which is obtained by encapsulating the microfluidic mixer in any of the above embodiments.

[0203] The following experimental comparison is conducted between the microfluidic chip provided in some embodiments of the present disclosure (hereinafter referred to as Metis chip, see Figure 1) and the microfluidic chip comparative design in the related art (hereinafter referred to as DVBM chip, see Figure 5).

[0204] Experimental Example 1: Lab Chip Preparation and Lipid Nanoparticle Preparation

[0205] Preparation of polydimethylsiloxane (PDMS) chip: Soft lithography technology is used to replicate the reverse structure of the channel structure on the silicon mold. Then, according to the ratio of 10:1, the A and B glue components are stirred and vacuumed to remove bubbles to obtain PDMS glue, which is then poured into the silicon mold and dried at 85°C for 30 to 40 minutes. Then, after steps such as stripping, cutting, and punching, a PDMS base with the target channel structure is obtained. The base and the glass bottom are then plasma cleaned and bonded to obtain a PDMS chip. METIS chips and DVBM chips are prepared according to the above method. The structure of the METIS chip is shown in Figure 4. The METIS chip is a three-inlet channel chip, or a "cross" channel inlet. The width of the channel 3 of the mixing unit 10 is 140μm and the depth is 75μm. The angle formed between the second side wall sections 302 of two adjacent mixing units 10 is 103°. The structure of the DVBM chip is shown in FIG5 . It is a two-entry channel chip with a channel width of 140 μm, a depth of 75 μm, and an annular channel angle of 120°.

[0206] Lipid nanoparticle preparation: Cationic lipid (DLin-MC3-DMA), ionizable phospholipid (DSPC), PEGylated lipid (PEG2000-DMG), and cholesterol were dissolved in anhydrous ethanol at a mass ratio of 50:10:1.5:38.5 to obtain an organic phase. The nucleic acid drug (luc mRNA) was dissolved in 0.1 M citric acid-sodium citrate buffer at pH 4 to prepare an aqueous phase with a nucleic acid content of 0.1 mg / mL. The organic and aqueous phases were pumped into the chip through the channel inlet at a ratio of 1:3. The organic phase entered through the second injection port 205, and the aqueous phase entered through the first injection port 204, with a total flow rate of 5 mL / min. The mixed solution was collected at the outlet. PBS buffer was added to dilute the mixed solution at a ratio of 1:4 to obtain a nucleic acid nanoparticle suspension. The nanoparticles were then characterized by dynamic light scattering (DLS) and tested for encapsulation efficiency. The results are shown in Figures 6 and 7.

[0207] Among them, lab chip preparation usually refers to the process of making small chips or micro devices on a laboratory scale.

[0208] Experimental Example 2: Pilot Chip Preparation and Nucleic Acid Nanoparticle Preparation

[0209] Preparation of glass chip: Glass chip can be prepared by laser etching and wet etching process. In this experiment, the laser etching method is used to etch the METIS chip channel structure on a glass substrate, and then bonded with another glass substrate to obtain the target chip. The METIS chip and DVBM chip are prepared according to the above method. The structure of the METIS chip is shown in Figure 4. The width of the channel 3 of the mixing unit 10 of the METIS chip is 700μm, the depth is 700μm, and the angle formed between the second side wall sections 302 of the two adjacent mixing units 10 is 103°. The structure of the DVBM chip is shown in Figure 5. The channel width is 700μm and the depth is 700μm. The mixing units are connected by connecting channels, and the angle between the two adjacent connecting channels is 120°.

[0210] Preparation of Nucleic Acid Nanoparticles: Refer to the sample preparation method of Experimental Example 1 to obtain an organic phase and an aqueous phase. The organic and aqueous phases were pumped into the chip through the channel inlet at a ratio of 1:3. The organic phase entered through the second injection port 205, and the aqueous phase entered through the first injection port 204, with a total flow rate of 7.5 L / h, and mixed within the chip. The mixed solution was collected at the outlet. The mixed solution at the outlet was diluted online with PBS buffer at a dilution ratio of 1:4, and the diluted solution was collected to obtain a nucleic acid nanoparticle suspension. The nanoparticles were then characterized by DLS and the encapsulation efficiency was tested. The results are detailed in Figures 6 and 7.

[0211] Among them, pilot chip preparation refers to an intermediate stage of the chip manufacturing process after the successful development and optimization of chip design and preparation technology in a small-scale trial (laboratory scale), but before large-scale production.

[0212] Experimental Example 3: Amplification (GMP) Chip Preparation and Nucleic Acid Nanoparticle Preparation

[0213] Preparation of stainless steel chips: The CNC machine tool milling method is used to process the shapes of the upper and lower stainless steel covers, and then the channel structure of the METIS chip is etched on the stainless steel base of the upper cover. The sealing gasket is processed according to the contour of the stainless steel base of the lower cover, and then the upper cover, sealing gasket and lower cover are fixed together by screws to form an integrated stainless steel chip. The METIS chip and DVBM chip are prepared according to the above method. The structure of the METIS chip is shown in Figure 4. The channel 3 of the mixing unit 10 of the METIS chip has a width of 980μm and a depth of 980μm. The angle formed between the second side wall sections 302 of two adjacent mixing units 10 is 103°. The structure of the DVBM chip is shown in Figure 5. The channel width is 980μm and the depth is 980μm. Each mixing unit is connected by a connecting channel, and the angle between two adjacent connecting channels is 120°.

[0214] Preparation of Nucleic Acid Nanoparticles: Refer to the sample preparation method of Experimental Example 1 to obtain an organic phase and an aqueous phase. The organic and aqueous phases were pumped into the chip through the channel inlet at a ratio of 1:3. The organic phase entered through the second injection port 205, and the aqueous phase entered through the first injection port 204, with a total flow rate of 20 L / H. Mixing occurred within the chip, and the mixed solution was collected at the outlet. The mixed solution exiting the chip was diluted online with PBS buffer at a dilution ratio of 1:4, and the diluted solution was collected to obtain a nucleic acid nanoparticle suspension. The nanoparticles were then characterized by DLS and tested for encapsulation efficiency. The results are detailed in Figures 6 and 7.

[0215] Among them, scale-up (GMP) chip preparation refers to the large-scale production process of chips carried out in accordance with Good Manufacturing Practice (GMP).

[0216] The results of Experimental Examples 1-3 show that under different flow rate (scale) conditions, the particle size (SIZE) and particle size distribution (PDI) of nucleic acid nanoparticles prepared using the METIS chip and the DVBM chip provided in the embodiments of the present disclosure did not differ significantly. However, the encapsulation efficiency (EE%) of nucleic acid nanoparticles prepared using the DVBM chip decreased significantly with increasing flow rate, with an EE% <89% at a mixed flow rate of 20 L / H. In contrast, the encapsulation efficiency of the METIS chip provided in the embodiments of the present disclosure did not change significantly, with EE% exceeding 90%. Combined with Experimental Example 4, it can be seen that the EE% of the METIS chip provided in the embodiments of the present disclosure remained greater than 90% at a flow rate of 32 L / H.

[0217] In addition, the results of Experimental Examples 1 to 3 show that the METIS chip structure design has good compatibility with different materials, such as PDMS, glass, and stainless steel, and there are no significant differences in their particle size, particle size distribution, and encapsulation efficiency.

[0218] The purpose of Experimental Examples 1 to 3 is to illustrate that the chip provided by the embodiments of the present disclosure has low restrictions on materials and sizes, and that different materials and sizes have no significant differences in particle size, particle size distribution, and encapsulation efficiency.

[0219] Experimental Example 4: Compatibility test of the chip with different traffic flows

[0220] Stainless steel chip preparation: A METIS chip was prepared according to the stainless steel chip preparation method described in Experimental Example 3. The channel 3 of the METIS chip mixing unit 10 had a width of 700 μm and a depth of 1000 μm. Each mixing unit was connected by a connecting channel, and the angle between two adjacent connecting channels was 103°.

[0221] Preparation of nucleic acid nanoparticles: Prepare according to the method in Experimental Example 3.

[0222] The organic and aqueous phases were injected according to the method described in Experimental Example 3, with total flow rates of 7.5 h / L, 20 h / L, and 32 h / L at the chip outlet, respectively. The mixed solution was collected at the outlet. The mixed solution exiting the chip was diluted online with PBS buffer at a dilution ratio of 1:4, and the diluted solution was collected to obtain a nucleic acid nanoparticle suspension. The nanoparticles were then characterized by DLS and the encapsulation efficiency was measured. The results are detailed in Figures 8 and 9.

[0223] Experimental results show that under the conditions of chip mixed flow rates of 7.5H / L, 20H / L, and 32H / L, there is no significant difference in the encapsulation efficiency (EE%), particle size, and particle size distribution. This shows that the chip channel structure design is highly compatible with different flow rates (or scales), and a single chip can simultaneously meet the production needs of different batches.

[0224] The purpose of Experiment 4 is to illustrate that the chip provided by the embodiment of the present disclosure is also suitable for high flow rate production, thereby improving production efficiency. However, the DVBM chip has low mixing efficiency and its encapsulation efficiency decreases with increasing flow rate, making it only suitable for production under low flow conditions.

[0225] Because LNP nanoparticle microfluidic production is a continuous process, newly prepared nanoparticles have poor physical stability and are prone to aggregation and fusion, requiring prompt entry into subsequent dilution and ultrafiltration processes. If the flow rate is too low or the preparation time is too long, the particles become unstable and the encapsulation efficiency is reduced. Therefore, the METIS chip provided in the embodiments of the present disclosure is preferred.

[0226] Experimental Example 5: Comparison of Chip Mixing Efficiency between Dual- and Triple-Channel Inlets

[0227] Chip Preparation: A chip with a METIS structure was prepared using the glass chip preparation method described in Experimental Example 2. Referring to Figure 3 , a dual-channel inlet chip has a Y-shaped inlet. The channel 3 of the mixing unit 10 has a width of 700 μm and a depth of 700 μm. The angle between the second sidewall segments 302 of two adjacent mixing units 10 is 103°.

[0228] 4 , a three-channel inlet chip is shown, in which the first liquid injection port 204 is split into a first liquid inlet channel 201 and a third liquid inlet channel 203 , forming a cross-shaped intersection inlet with the second liquid inlet channel 202 . The width of channel 3 of the mixing unit 10 is 700 μm and the depth is 700 μm.

[0229] Preparation of nucleic acid nanoparticles: According to the method in Experimental Example 3, nucleic acid nanoparticles were scaled up and prepared at a total flow rate of 7.5 H / L (total flow rate at the chip outlet), and the nanoparticles were characterized by DLS and the encapsulation efficiency was tested. The results are detailed in Figures 10 and 11.

[0230] The experimental results show that there is no significant difference in the characterization results of samples prepared by the METIS chips with dual-channel and triple-channel inlets provided in the embodiments of the present disclosure, indicating that the two chip designs have no effect on the quality of nucleic acid nanoformulations.

[0231] The purpose of Experimental Example 5 is to illustrate that the mixing unit 10 provided in the embodiment of the present disclosure can achieve better mixing efficiency and reduce the requirements for the inlet.

[0232] Experimental Example 6: Investigation of Chip Mixing Efficiency

[0233] Chip preparation: METIS chip and DVBM chip were prepared respectively according to the PDMS chip preparation method in Experimental Example 1. The channel width of the mixing unit was 140 μm and the depth was 75 μm.

[0234] Mixing efficiency test: Two chips were mounted separately in an inverted fluorescence microscope. PBS (pH 7.4) was passed through the aqueous phase, and a fluorescein ethanol solution of a certain concentration was passed through the organic phase. The flow rate ratio of the organic phase to the aqueous phase was 1:3, and the total flow rate was 5 mL / min. When the flow rate stabilized, a high-speed fluorescence microscope image was taken (as shown in Figure 12). The fluorescence value at the confluence of each mixing unit was read, and the mixing index (MI) was calculated based on the fluorescence difference per unit distance within the channel. MI = 1 indicates no mixing, and MI = 0.1 indicates complete mixing. The mixing effect diagram was then plotted (Figure 13), with the mixing index as the ordinate and the number (or position) of mixing units as the abscissa. Furthermore, since the total liquid flow rate V was 5 mL / min and the channel cross-sectional area was 140 μm x 75 μm, the time (MT) to complete mixing was calculated by reading the channel distance L required for complete mixing.

[0235] For the calculation of MI, please refer to the reference: RSC Adv., 2017, 7, 10906, formula (2). The mixing index is usually defined based on the ratio of fluorescence differences or normalized differences. The specific calculation formula may vary depending on the specific needs and applications of the research.

[0236] Surprisingly, the MI of the first mixing unit of the METIS chip channel design can reach 0.191 (mixing efficiency is 80.94%), and complete mixing can be achieved in the second mixing unit (mixing efficiency is as high as 98%), which is significantly higher than that of the DVBM chip (see Table 1).

[0237] The formation mechanism of nucleic acid-loaded lipid nanoparticles (LNPs) is achieved by mixing and diluting the lipid components in the organic phase and the nucleic acid components in the aqueous phase, reducing the concentration of the organic phase, and promoting the self-assembly of the phospholipid components and the nucleic acid components. Different organic phase concentrations can cause nanoparticles to form different morphologies, such as spheres, films, and tubes. However, the film-shaped and tubular shapes have low or no encapsulation efficiency for mRNA, which significantly affects the encapsulation efficiency of the overall nanoparticles. It also affects the size and particle size distribution of the nanoparticles. The mixing efficiency refers to the mixing ratio achieved per unit time. The higher the mixing efficiency, the shorter the mixing time (ms level). Instantaneous and sufficient mixing can avoid the formation of concentration gradients in the organic phase during the dilution process, thereby avoiding the production of nanoparticles with different morphologies, sizes, and encapsulation rates.

[0238] Therefore, the METIS chip channel design has better mixing efficiency, allowing the mixed solution to instantly reach a specific organic phase concentration, improving the nanoparticle encapsulation rate, which is crucial to the quality of the nanoparticles.

[0239] Table 1

[0240] Experimental Example 7: METIS Chip Angle Compatibility Investigation

[0241] The mixing units in the METIS chip are arranged at specific angles. Different angles can alter fluid motion, reducing mixing efficiency and, consequently, affecting product quality. To examine the METIS chip's compatibility with angles and investigate the impact of different angles on fluid mixing efficiency, this paper employed the mixing efficiency research method from Experimental Example 6, studying the chip's mixing efficiency at angles ranging from 63° to 143°.

[0242] Chip Preparation: Chips with METIS structures at different angles were prepared using the PDMS chip preparation method described in Experimental Example 1. The angles α were 63°, 83°, 103°, 123°, and 143°, respectively. The channel 3 of the mixing unit 10 had a width of 140 μm and a depth of 75 μm. The angles here refer to the angle formed between the second sidewall segments 302 of two adjacent mixing units 10. See Figures 14a to 14e for the METIS chip. See Figure 14f for the DVBM chip.

[0243] Mixing Efficiency Test: Mixing efficiency was assessed using the mixing index determination method described in Experimental Example 6. The results are detailed in Table 2. The results show that the mixing index (MI) in mixing unit 1 increases slightly with increasing angle, remaining below 0.3, significantly lower than the PNI (0.73). Furthermore, the MI values ​​for all angles in mixing unit 2 have dropped below 0.1, indicating complete mixing. This mixing efficiency data demonstrates the METIS chip's high compatibility with various angles.

[0244] The purpose of Experimental Example 7 is to illustrate that different angles between adjacent mixing units will not have a significant impact on the mixing efficiency of the chip.

[0245] Table 2

[0246] Experimental Example 8: Dimensional compatibility study of GMP stainless steel chips

[0247] The processing of chip channels in different batches often has a certain precision deviation (±5%). The size variation of the chip within a certain range may affect the product quality of nucleic acid nanoparticles. Therefore, this experiment examined the size range of 700μm to 1000μm, equivalent to 850μm±150μm, with a deviation of 17.6%, which is about 3 times the processing accuracy. This is to examine the impact of channel design in this size range on the product under the same flow rate.

[0248] Following the stainless steel chip preparation method described in Experimental Example 3, METIS chips with different channel sizes were prepared. The channel width and depth (μm) were 700 x 700, 700 x 1000, and 980 x 980, respectively. These chips were assembled using a cover plate and a sealing gasket to create a well-sealed integrated chip.

[0249] Nucleic Acid Nanoparticle Preparation: Following the method described in Experimental Example 3, nucleic acid nanoparticles were scaled up and prepared at a total chip flow rate of 20 h / L. The nanoparticles were then characterized by DLS and tested for encapsulation efficiency. The experimental data showed that at the same flow rate, varying the channel size within a certain range did not significantly affect the encapsulation efficiency, particle size, and size distribution of the nucleic acid particles (see Table 3). This demonstrates that the METIS chip design maintains good compatibility within a size range with a deviation of 17.6%.

[0250] The purpose of Experimental Example 8 is to illustrate that the processing deviation of the chip size range and the channel size range will not have a great impact on the mixing efficiency of the chip. The chip deviation provided by the embodiment of the present disclosure is 17.6%, which is about 3 times the processing accuracy. There is no significant difference in DLS characterization and encapsulation rate. Therefore, it can reduce the processing difficulty and reduce the processing cost.

[0251] Table 3

[0252] Experimental Example 9: Design of Chip Structure

[0253] Chip Preparation: A METIS chip and a DVBM chip were prepared using the PDMS chip preparation method described in Experimental Example 1. The mixing unit channel had a width of 140 μm and a depth of 75 μm. The mixing effect was evaluated using the mixing index determination method described in Experimental Example 6. The results are shown in Figure 13.

[0254] Results showed that the mixing efficiency of the METIS chip was significantly superior to that of the DVBM chip; the METIS chip achieved complete mixing in the second mixing unit, while the DVBM chip did not achieve complete mixing until the fourth mixing unit. Furthermore, the METIS chip's mixing unit has rounded corners, eliminating dead corners and making it easy to clean and reusable, making it more suitable for industrial production.

[0255] Similarly, microfluidic chips with different patterns were prepared according to the above preparation method and channel dimensions (Figures 15, 19-21), and all of them could achieve complete mixing (MI<0.1) in the second mixing unit.

[0256] The fluid mixer for dual-channel bifurcated liquid flows provided in the embodiments of the present disclosure has each channel containing an arc-shaped channel portion and an angled channel portion. The mixing efficiency of the structural mixer is higher than that of the DVBM chip, and has unexpected technical effects. In addition, the corners of the mixing unit are rounded in design, with no dead angles and easy to clean, and can be reused, making it more suitable for industrial production. Some experimental examples of the present disclosure disclose a new structure of a microfluidic mixing device, and disclose a processing method for the same on materials such as PDMS, glass, and stainless steel. The channel structure and external structure are simple and easy to process, and can be manufactured using CMC CNC lathes, laser etching, chemical etching, and injection molding tools. The method is simple and greatly reduces the preparation cost.

[0257] Referring to Figures 5 and 14f, the DVBM mixing unit involved in the embodiments of the present disclosure includes a fluid inlet, a fluid outlet, and two branches. The inlets of the two branches are connected to the fluid inlet for introducing fluid, and the outlets of the two branches are connected to the fluid outlet for withdrawing fluid. The two branches form a circular structure. The fluid inlet and the fluid outlet are not aligned radially with respect to the circular structure.

[0258] The DVBM chip includes at least two DVBM mixing units, each connected by a connecting channel. The angle between two adjacent connecting channels is 120°. The connecting channel connects the fluid outlet of one DVBM mixing unit to the fluid inlet of the other DVBM mixing unit.

[0259] Based on the above-mentioned embodiments of the present disclosure, in the absence of explicit negation or conflict, the technical features of one embodiment may be beneficially combined with one or more other embodiments.

[0260] Although some specific embodiments of the present disclosure have been described in detail through examples, those skilled in the art will understand that the above examples are for illustration only and are not intended to limit the scope of the present disclosure. Those skilled in the art will understand that the above embodiments may be modified or some technical features may be replaced with equivalents without departing from the scope and spirit of the present disclosure. The scope of the present disclosure is defined by the appended claims.

Claims

1. A microfluidic mixer, comprising: A mixing unit (10), including an inlet end (1), an outlet end (2), and two channels (3). The inlets of the two channels (3) are both connected to the inlet end (1), and the outlets of the two channels (3) are both connected to the outlet end (2); In a cross-section taken along the fluid flow direction, at least one of the two channels (3) includes two side walls (31), and at least one side wall (31) includes a first side wall section (301) and a second side wall section (302). The first side wall section (301) and the second side wall section (302) have different centers of curvature. The first side wall section (301) is an arc section, and the first side wall section (301) intersects with the second side wall section (302) to form a first corner (321).

2. The microfluidic mixer according to claim 1, wherein the second side wall section (302) is a straight line section.

3. The microfluidic mixer according to claim 1 or 2, wherein the first corner (321) is an arc corner.

4. The microfluidic mixer according to any one of claims 1 to 3, wherein both the first side wall section (301) and the second side wall section (302) smoothly extend in the direction from the inlet end (1) to the outlet end (2).

5. The microfluidic mixer according to any one of claims 1 to 4, including at least two series-connected dual-channel mixing units, one of which is the mixing unit (10); preferably, including at least two series-connected mixing units (10); preferably, including at least one series-connected mixing unit (10) and a DVBM mixing unit.

6. The microfluidic mixer according to any one of claims 1 to 5, wherein the lengths of the two channels (3) are the same.

7. The microfluidic mixer according to any one of claims 1 to 6, wherein the two channels (3) are symmetrically arranged. Preferably, the two channels (3) are symmetrically arranged with respect to the center of the mixing unit (10), or the two channels (3) are symmetrically arranged with respect to the central axis of the mixing unit (10).

8. The microfluidic mixer according to any one of claims 1 to 7, wherein the two channels (3) are symmetrically arranged with respect to the connection line between the inlet end (1) and the outlet end (2) of the mixing unit (10).

9. The microfluidic mixer according to any one of claims 1 to 8, wherein the two channels (3) are in the same plane or in different planes.

10. The microfluidic mixer according to any one of claims 1 to 9, wherein the two channels (3) are formed into a racetrack shape or a fan shape.

11. The microfluidic mixer according to any one of claims 1 to 10, wherein the two side walls (31) are respectively a first side wall (311) and a second side wall (312), and both the first side wall (311) and the second side wall (312) are composed of an arc-shaped first side wall section (301) and a straight-line-shaped second side wall section (302).

12. The microfluidic mixer according to claim 11, wherein the two channels (3) are respectively a first channel (3a) and a second channel (3b); A first side wall segment (301) of the first channel (3a) is connected to the inlet end (1), a second side wall segment (302) of the second channel (3b) is connected to the inlet end (1), a second side wall segment (302) of the first channel (3a) is connected to the outlet end (2), and a first side wall segment (301) of the second channel (3b) is connected to the outlet end (2); or, A second side wall segment (302) of the first channel (3a) is connected to the inlet end (1), a second side wall segment (302) of the second channel (3b) is connected to the inlet end (1), a first side wall segment (301) of the first channel (3a) is connected to the outlet end (2), and a first side wall segment (301) of the second channel (3b) is connected to the outlet end (2).

13. The microfluidic mixer according to claim 11 or 12, wherein A first side wall segment (301b) of a second side wall (312) of the first channel (3a) intersects a second side wall segment (302b) of a second side wall (312) of the second channel (3b) at the inlet to form a second corner (322); a second side wall segment (302b) of the second side wall (312) of the first channel (3a) intersects a first side wall segment (301b) of the second side wall (312) of the second channel (3b) at the outlet to form a third corner (323); or, A second side wall segment (302b) of a second side wall (312) of the first channel (3a) intersects a second side wall segment (302b) of a second side wall (312) of the second channel (3b) at the inlet to form a fourth corner (324); A first side wall segment (301b) of a second side wall (312) of the first channel (3a) intersects a first side wall segment (301b) of a second side wall (312) of the second channel (3b) at the outlet to form an arc.

14. The microfluidic mixer according to claim 13, wherein the second corner (322), the third corner (323), and the fourth corner (324) are arc-shaped corners.

15. The microfluidic mixer according to any one of claims 1 to 14, wherein adjacent side walls of the two channels (3) are connected to form an island; preferably, the shape of the island is quasi-rectangular or fan-shaped.

16. The microfluidic mixer according to any one of claims 1 to 15, further comprising at least two liquid inlet channels (20), and the at least two liquid inlet channels (20) are all communicated with the inlet end (1) of the mixing unit (10).

17. The microfluidic mixer according to claim 16, wherein the at least two liquid inlet channels (20) include a first liquid inlet channel (201), a second liquid inlet channel (202), and a third liquid inlet channel (203); The inlets of the first liquid inlet channel (201) and the third liquid inlet channel (203) are configured to be both connected to a first solution providing device, and the outlets of the first liquid inlet channel (201) and the third liquid inlet channel (203) are both connected to the inlet end (1) of the mixing unit (10); The inlet of the second liquid inlet channel (202) is configured to be connected to a second solution providing device, and the outlet of the second liquid inlet channel (202) is connected to the inlet end (1) of the mixing unit (10).

18. The microfluidic mixer according to any one of claims 1 to 17, wherein each of the two channels (3) includes a first channel segment (31a) and a second channel segment (31b), and a first corner (321) is formed at the connection between the first channel segment (31a) and the second channel segment (31b).

19. The microfluidic mixer according to claim 18, wherein one of the first channel segment (31a) and the second channel segment (31b) is an arc-shaped channel, and the other of the first channel segment (31a) and the second channel segment (31b) is a straight channel.

20. The microfluidic mixer according to claim 18 or 19, wherein the widths of the first channel segment (31a) and / or the second channel segment (31b) are consistent along the fluid flow direction from the inlet end (1) to the outlet end (2).

21. The microfluidic mixer according to any one of claims 18 to 20, wherein the two channels (3) are respectively a first channel (3a) and a second channel (3b); The first channel segment (31a) of the first channel (3a) is connected to the inlet end (1), and the second channel segment (31b) of the second channel (3b) is connected to the inlet end (1); The second channel segment (31b) of the first channel (3a) is connected to the outlet end (2), and the first channel segment (31a) of the second channel (3b) is connected to the outlet end (2); or, The second channel segment (31b) of the first channel (3a) is connected to the inlet end (1), and the second channel segment (31b) of the second channel (3b) is connected to the inlet end (1); The first channel segment (31a) of the first channel (3a) is connected to the outlet end (2), and the first channel segment (31a) of the second channel (3b) is connected to the outlet end (2).

22. A microfluidic mixer, which includes a mixing unit (10), the mixing unit (10) includes an inlet end (1), an outlet end (2) and two channels (3), the inlets of the two channels (3) are both connected to the inlet end (1), the outlets of the two channels (3) are both connected to the outlet end (2), and the impedances of the two channels (3) are the same.

23. The microfluidic mixer according to claim 22, wherein each of the two channels (3) includes a first channel segment (31a) and a second channel segment (31b), and a first corner (321) is formed at the connection between the first channel segment (31a) and the second channel segment (31b).

24. The microfluidic mixer according to claim 23, wherein one of the first channel segment (31a) and the second channel segment (31b) is an arc-shaped channel, and the other of the first channel segment (31a) and the second channel segment (31b) is a straight channel.

25. The microfluidic mixer according to claim 23 or 24, wherein the widths of the first channel segment (31a) and / or the second channel segment (31b) are consistent along the fluid flow direction from the inlet end (1) to the outlet end (2).

26. The microfluidic mixer according to any one of claims 23 to 25, wherein the two channels (3) are respectively a first channel (3a) and a second channel (3b); the first channel segment (31a) of the first channel (3a) is connected to the inlet end (1), and the second channel segment (31b) of the second channel (3b) is connected to the inlet end (1); the second channel segment (31b) of the first channel (3a) is connected to the outlet end (2), and the first channel segment (31a) of the second channel (3b) is connected to the outlet end (2); or, the second channel segment (31b) of the first channel (3a) is connected to the inlet end (1), and the second channel segment (31b) of the second channel (3b) is connected to the inlet end (1); the first channel segment (31a) of the first channel (3a) is connected to the outlet end (2), and the first channel segment (31a) of the second channel (3b) is connected to the outlet end (2).

27. The microfluidic mixer according to any one of claims 22 to 26, wherein the two channels (3) are arranged to form a racetrack shape or a fan shape.

28. The microfluidic mixer according to any one of claims 22 to 27, wherein the inlet end (1) and the outlet end (2) are aligned along a straight line.

29. The microfluidic mixer according to any one of claims 22 to 28, wherein the angle between the axis of the inlet end (1) and the axis of the outlet end (2) is 180 degrees.

30. The microfluidic mixer according to any one of claims 22 to 29, wherein the width or height range of each of the two channels (3) is 20 μm to 5 mm.

31. The microfluidic mixer according to any one of claims 22 to 30, comprising at least two tandem dual-channel mixing units, one of which is the mixing unit (10); preferably, comprising at least two tandem mixing units (10); preferably, comprising at least one mixing unit (10) and a DVBM mixing unit in series.

32. The microfluidic mixer according to claim 31, wherein the outlet ends (2) and the inlet ends (1) of the plurality of mixing units (10) are aligned with each other in a straight line.

33. The microfluidic mixer according to claim 31 or 32, wherein the angle between the axes of the outlet ends (2) and the axes of the inlet ends (1) of the plurality of mixing units (10) is 180 degrees.

34. The microfluidic mixer according to any one of claims 22 to 33, wherein the lengths of the two channels (3) are the same.

35. The microfluidic mixer according to any one of claims 22 to 34, wherein the two channels (3) are symmetrically arranged with respect to the center of the mixing unit (10), or the two channels (3) are symmetrically arranged with respect to the central axis of the mixing unit (10).

36. The microfluidic mixer according to any one of claims 22 to 35, wherein the two channels (3) are symmetrically arranged with respect to the connection line between the inlet end (1) and the outlet end (2) of the mixing unit (10).

37. The microfluidic mixer according to any one of claims 22 to 36, wherein the adjacent side walls of the two channels (3) of the mixing unit (10) are connected to form an island, and the shape of the island includes a quasi-rectangle or a sector.

38. The microfluidic mixer according to any one of claims 22 to 37, comprising at least two of the mixing units (10) connected in series.

39. A microfluidic chip obtained by encapsulating the microfluidic mixer according to any one of claims 1 to 38.

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