CN116651525A - Microfluidic chip and method for preparing liquid drops - Google Patents

Abstract

The present invention relates to a microfluidic chip, a first syringe needle and a second syringe needle are connected to an alignment box opposite to each other and define a first channel, a third syringe needle is connected to the alignment box and defines a second channel leading to the first channel, a first sealing tube and a second sealing tube are respectively inserted into opposite ends of the first channel in a sealing way, the first capillary tube is inserted into the first sealing tube in a sealing way and is installed, the second capillary tube is inserted into the second sealing tube in a sealing way and is installed in a sealing way, and by means of elastic alignment of the first sealing tube and the second sealing tube, a conical tip of the first capillary tube coaxially faces to an inner end of the second capillary tube to provide a liquid drop generating area. The invention also relates to a method for preparing liquid drops by using the microfluidic chip. According to the microfluidic chip disclosed by the invention, the sealing, coaxial alignment fixation and convenient sample injection of a non-adhesive process are realized at low cost, and the detachable, cleaning and repeated use are realized, so that the microfluidic chip has important application value for popularization and preparation of micro drops.

Description

Microfluidic chip and method for preparing liquid drops

Technical Field

The present invention relates to a chip, and more particularly, to a microfluidic chip and a method of preparing droplets.

Background

Microfluidic technology is a technology that manipulates tiny volumes of liquid in a microscale chip channel, with which micro-droplets with highly monodisperse, highly controllable size and structure can be produced. The micro-droplets provide excellent templates for preparing highly monodisperse micro-particles with diversified structures, and are widely used in the fields of drug delivery, biological templates, cell culture, microreactors and the like.

Common microfluidic chips for droplet preparation are classified into flat plates and capillary tubes. Most of the flat plate materials are polymers (batch injection molding, mold opening and PDMS production efficiency are low), high temperature resistance and organic solution corrosion resistance are not realized, and the chip is difficult to disassemble and assemble, so that the cleaning and the repeated use are not facilitated. The glass capillary microfluidic chip adopts a capillary as a functional unit for generating and collecting liquid drops, and the chip gradually becomes a widely used micro-liquid drop preparation device due to the fact that glass has excellent light transmittance, excellent high pressure resistance, biocompatibility, stable surface property, organic solvent corrosion resistance and the like.

Glass capillary microfluidic chip devices are typically coaxially nested with hollow capillaries of different thicknesses, and the coaxially nested microchannel structure can realize the preparation of single-emulsion microdroplets or multiple-emulsion microdroplets with core-shell structures. CN106622407a provides a microfluidic chip that is built up with glass capillaries using a glass slide and attached and fixed to the glass capillaries by dispensing needles using an adhesive. The assembled microfluidic chip can be constructed by manual operation. Also disclosed in patent document CN102580799a, which is a technology of cutting a microchannel on a glass slide, inserting a glass capillary into the microchannel, and bonding and sealing the glass slide and the interface by an adhesive. CN112517096a discloses a method for preparing a chip substrate by using 3D printing technology and adopting materials such as plastics, metals, polymers and the like, and constructing a capillary microfluidic chip by using a needle alignment platform, a needle alignment device, a fixer and the like.

The technical scheme provides a method for coaxially arranging and fixing the capillaries, and the common point is that the chips are assembled in a modularized mode. It should be noted that, in the process of chip assembly, manual operation is easy to occur, and the problem that the capillary cannot guarantee accurate three-dimensional coaxial arrangement. Secondly, the fixing of the capillary tube in the chip and/or the sealing of the micro-channel can use an adhesive, is not resistant to organic solvents and is easy to leak, and once the chip is partially blocked or damaged, the liquid cannot normally flow so that the chip is scrapped, and the manufacturing efficiency and the manufacturing quality of the chip are seriously reduced. In the technical content of the capillary microfluidic chip disclosed at present, the capillary microfluidic chip is mostly constructed in a modularized splicing mode of glass capillary, micro-channel structure, sample injection structure, fixing structure, sealing structure and the like. The construction mode involves multiple sealing links, has high requirements on connecting pieces, cannot avoid the use of adhesives, and is difficult to ensure the tightness of chips. Besides the coaxial position relation of the capillary, the fixing of the capillary and the sealing of the micro-channel are also technical difficulties of the capillary microfluidic chip.

The patents CN113797986a and CN113058669a solve the above problems to some extent, but the specially designed assembly parts are all threaded and have high precision requirements, and the cost is high (hundred yuan level).

Disclosure of Invention

In order to solve the problems that the capillary tube in the prior art is difficult to coaxially align, the sealing of a device is not firm, the glass capillary tube is easy to damage, the processing precision requirement of a threaded connecting piece is high (the cost is high), and the like, the invention provides a microfluidic chip and a method for preparing liquid drops.

The microfluidic chip according to the present invention comprises an alignment box, a first syringe needle, a second syringe needle, a third syringe needle, a first sealing tube, a second sealing tube, a first capillary and a second capillary, wherein the first syringe needle and the second syringe needle are connected to the alignment box opposite to each other and define a first channel, the third syringe needle is connected to the alignment box and defines a second channel leading to the first channel, the first sealing tube and the second sealing tube are respectively inserted at opposite ends of the first channel in a sealing manner, the first capillary is inserted in the first sealing tube in a sealing manner, the second capillary is inserted in the second sealing tube in a sealing manner, the conical tip of the first capillary is aligned coaxially over the inner end of the second capillary by means of elasticity of the first sealing tube and the second sealing tube in a sealing manner, so as to provide a droplet generation area.

Preferably, the first capillary communicates with the first passage and the lumen of the first syringe needle, and the second capillary communicates with the first passage and the lumen of the second syringe needle, and the tapered tip of the first capillary is inserted into the inner end of the second capillary directly below the second passage.

Preferably, the alignment box has a box body, a first protruding tube protruding from the left side of the box body, a second protruding tube protruding from the right side of the box body, and a third protruding tube protruding from the upper side of the box body, the first syringe needle cover being connected to and in communication with the first protruding tube, the second syringe needle cover being connected to and in communication with the second protruding tube, the third syringe needle cover being connected to and in communication with the third protruding tube.

Preferably, the second channel is vertically accessed into the middle of the first channel to form a T-shaped internal channel.

Preferably, the first or second sealing tube is a silica gel or rubber tube.

Preferably, the microfluidic chip comprises two alignment boxes, two first syringe needles, two second syringe needles, two third syringe needles, a first capillary and a second capillary, wherein one first syringe needle, one second syringe needle, one third syringe needle is in communication with one alignment box to provide a first module, and the other first syringe needle, the other second syringe needle, the other third syringe needle is in communication with the other alignment box to provide a second module.

Preferably, the microfluidic chip further comprises two first sealing pipes, two second sealing pipes and a connecting pipe connecting the first module and the second module, wherein the two first sealing pipes and the two second sealing pipes are respectively inserted into opposite ends of a first channel of the first module and the second module in a sealing way, one end of the connecting pipe penetrates through a second syringe needle of the first module and the second sealing pipe to be inserted into the first channel and to be terminated below the second channel, and the other end of the connecting pipe penetrates through a first syringe needle of the second module and the first sealing pipe to be inserted into the first channel and to be terminated below the second channel.

Preferably, the first capillary tube is installed to communicate the inner cavity of the first syringe needle of the first module and the inner cavity of the connection tube by passing through the first sealing tube and the second sealing tube of the first module in sequence, and the second capillary tube is installed to communicate the inner cavity of the second syringe needle of the second module and the inner cavity of the connection tube by passing through the second sealing tube and the first sealing tube of the second module in sequence.

According to the method for preparing liquid drops by using the microfluidic chip, the inner phase enters the first capillary through the first syringe needle, the outer phase enters the second channel through the third syringe needle, and the liquid drops generated at the conical opening of the conical tip of the first capillary are discharged through the second capillary and the second syringe needle.

Preferably, multiple microfluidic chips are nested to make multiple emulsions.

According to the microfluidic chip disclosed by the invention, the sealing, coaxial alignment fixation and convenient sample injection of a non-adhesive process are realized at low cost, and the detachable, cleaning and repeated use are realized, so that the microfluidic chip has important application value for popularization and preparation of micro drops.

Drawings

Fig. 1 is a schematic view of the overall structure of a microfluidic chip according to a preferred embodiment of the present invention.

Fig. 2 is an exploded view of the microfluidic chip of fig. 1.

Fig. 3 is a perspective view of the alignment box of fig. 2.

Fig. 4 is a cross-sectional view of the alignment box of fig. 2.

Fig. 5 is a cross-sectional view of the microfluidic chip of fig. 1.

Fig. 6 corresponds to fig. 5, showing the mechanism of action of the microfluidic chip.

Fig. 7 is a microscopic image of the resulting droplets.

Fig. 8 is a histogram of the diameter distribution of the obtained droplets.

Fig. 9 shows the diameters of droplets produced at different flow rates.

Fig. 10 is a schematic view of the overall structure of a microfluidic chip according to another preferred embodiment of the present invention.

Fig. 11 is a cross-sectional view of the microfluidic chip of fig. 10 and illustrates the mechanism of action thereof.

Detailed Description

Preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

As shown in fig. 1-2, the microfluidic chip according to one preferred embodiment of the present invention includes an alignment box 1, a first syringe needle 2, a second syringe needle 3, and a third syringe needle 4, wherein the alignment box 1 is a core module having a box body 11, a first boss 12, a second boss 13, and a third boss 14, the first boss 12 protrudes from the left side of the box body 11, the second boss 13 protrudes from the right side of the box body 11, the third boss 14 protrudes from the upper side of the box body 11, the first syringe needle 2 is coupled to and communicates with the first boss 12, the second syringe needle 3 is coupled to and communicates with the second boss 13, and the third syringe needle 4 is coupled to and communicates with the third boss 14.

It should be understood that the material of the alignment box 1 is not limited, and may be molded by 3D printing, machining, injection molding, or other processes, and the preferred material is plastic, cured resin, metal, or the like.

As shown in fig. 3 to 4, the first protruding tube 12 and the second protruding tube 13 are disposed opposite to each other and define a first passage 15 extending in a straight line together with the case 11, and the third protruding tube 14 defines a second passage 16 with the case 11, and the first passage 15 and the second passage 16 are vertically communicated. In the present embodiment, the second passage 16 is connected to the middle of the first passage 15 from above to form an inverted T-shaped internal passage. In this embodiment, the inner diameter of the inverted T-shaped internal passage is 3mm.

Returning to fig. 2, the microfluidic chip according to one preferred embodiment of the present invention further includes a first sealing tube 5, a second sealing tube 6, a first capillary tube 7 and a second capillary tube 8, the first sealing tube 5 and the second sealing tube 6 being inserted at opposite ends of the first channel 15, respectively, the first capillary tube 7 being inserted into the first sealing tube 5 to communicate the inner cavity of the first syringe needle 2 with the first channel 15, the second capillary tube 8 being inserted into the second sealing tube 6 to communicate the first channel 15 with the inner cavity of the second syringe needle 3, the tapered tip of the first capillary tube 7 being inserted into the inner end of the second capillary tube 8 just below the second channel 16, in conjunction with fig. 5. In this embodiment the inner diameter of the sealing tube 5,6 is 0.1mm smaller than the outer diameter of the capillary tube 7,8, so that sealing is achieved by an interference fit without gaps. In this embodiment, the first capillary 7 is drawn by a needle drawing machine, and the tapered tip of the front end facilitates the preparation of micro droplets, preferably having an inner diameter of 10 μm to 200 μm.

In particular, the sealing tubes 5,6 are highly elastic tubes, such as silicone or rubber tubes, which are positioned between the alignment box 1 and the capillaries 7,8 with a dimensional match to achieve a seal between the two. It should be understood that silica gel or rubber tubing is a commercially available product with excellent elasticity, with precise concentric inner and outer diameters. The sealing tubes 5,6 are inserted into the first passage 15 and fitted so that their outer diameters match the inner diameters of the first passage 15, i.e. self-sealing. The axes of the sealing pipes 5,6 are arranged correspondingly and concentrically. When the capillary tubes 7 and 8 are inserted into the sealing tubes 5 and 6, the capillary tubes 7 and 8 are pressed by silica gel or rubber tubes, the wall thickness is consistent, the pressure is consistent, and the capillary tubes 7 and 8 are automatically positioned at the axle center position, so that various adhesives and screw members are avoided. That is, the capillaries 7,8 are automatically coaxial after assembly.

It will be appreciated that the syringe needles 2,3,4 herein are commercially available products, either plastic or metal. Referring to fig. 5, the syringe needles 2,3,4 comprise a needle 21 and a connector 22 which are fixedly connected, wherein the needle 21 is a thin head, and the connector 22 is a flaring structure. The connector 22 is directly sleeved on the connecting pipes 12, 13, 14 (see fig. 2) of the alignment box 1, so that the assembly can be conveniently and reliably realized, and the sealing of the alignment box 1 and the syringe needles 2,3 and 4 is realized, thereby being simple and efficient. In this embodiment, the inner diameter of the needle 21 is larger than the outer diameter of the capillary tube 7,8, so that the capillary tube 7,8 will not touch the needle 21 to damage the capillary tube 7,8 when the capillary tube 7,8 is inserted into the needle 21 for installation, and the connection between the needle 21 of the syringe needle 2,3,4 and the external pipeline can be realized. Since the needle 21 is relatively strong and reliable, the external tubing is attached to protect the fragile capillaries 7,8 contained therein.

It will be appreciated that there is no need for a tight connection between the capillaries 7,8 and the needle 21, and that the capillaries 7,8 do not have to be inserted into the needle 21, but only into the interior of the connector 22, since the outlet of the syringe needle 2,3,4 is sealed by the sealing tube 5,6, the lumen of the syringe needle 2,3,4 can only communicate with the first channel 15 via the capillaries 7,8.

The specific use of the microfluidic chip according to the present embodiment is briefly described below.

As shown in fig. 6, the inner phase (e.g., water) first enters the lumen of the first syringe needle 2 and then passes through the first capillary 7 into the first passageway 15, and the outer phase (e.g., oil) first enters the lumen of the third syringe needle 4 and then enters the second passageway 16. In particular, the bottom end of the second channel 16 faces the tapered tip of the first capillary 7 to provide a droplet generation region, and the generated droplets enter the lumen of the second syringe needle 3 through the second capillary 8 and then are discharged through the second syringe needle 3.

Example 1

To demonstrate the performance of the microfluidic chip according to the invention, pure water (inner phase) and mineral oil mixed with 3% of surfactant Abil EM90 (outer phase) were used to generate a water-in-oil emulsion, the oil phase was collected by a second capillary 8 opposite to the first capillary 7, and the coaxial relationship was verified from microscopic images taken by an optical microscope.

In this example, the tip of the first capillary 7 has a size of 30 μm and the corresponding size of the second capillary 8 is 200 μm. The distance can be easily adjusted by stretching the capillary. A large number of 0.43nL droplets (FIGS. 7 and 8) with uniform size distribution (CV 5%) were rapidly prepared at a high generation frequency of 636Hz while the internal and external phase flow rates were maintained at 20 and 300. Mu.L/min, respectively. No significant coalescence was observed beyond 24 hours after production. That is, according to the present invention, uniform and stable droplets can be generated, and reliable effectiveness can be achieved.

It will be appreciated that by adjusting the size of the tapered tip of the first capillary 7, the size of the droplets generated can be adjusted accordingly. For example, the smaller the size of the tapered tip, the smaller the droplet. With a fixed tip size, the size of the droplets generated can be adjusted by adjusting the flow rate/flow ratio of the inner and outer phases. For example, the larger the flow rate of the external phase, the smaller the droplets, and the larger the flow rate of the internal phase, the larger the droplets. As shown in fig. 9, the change in the diameter of the droplet can be clearly seen by changing the flow rate ratio of the inner dispersed phase (Qd) and the outer continuous phase (Qc). Accordingly, the invention can control the diameter of the liquid drop according to the requirement and has wide applicability.

As shown in fig. 10, a microfluidic chip according to another preferred embodiment of the present invention includes two alignment boxes 1, 10, two first syringe needles 2, 20, two second syringe needles 3, 30, and two third syringe needles 4, 40. The left first syringe needle 2 is connected to and communicates with the left side of the left alignment box 1, the left second syringe needle 3 is connected to and communicates with the right side of the left alignment box 1, and the left third syringe needle 4 is connected to and communicates with the left alignment box 1 on the upper side, thereby providing a first module. The right first syringe needle 20 is connected to and communicates with the left side of the right alignment box 10, the right second syringe needle 30 is connected to and communicates with the right side of the right alignment box 10, and the right third syringe needle 40 is connected to and communicates with the right alignment box 10 on the upper side, thereby providing a second module.

As shown in fig. 11, the microfluidic chip according to another preferred embodiment of the present invention further includes a connection tube 9 connecting the first and second modules, a left end of which is inserted into the first channel 15 through the left second syringe needle 3 and the second sealing tube 6 of the first module and terminates below the second channel 16, and a right end of which is inserted into the first channel 15 through the right first syringe needle 20 and the first sealing tube 50 of the second module and terminates below the second channel 16.

In particular, the first capillary tube 7 of the present embodiment is installed to communicate the inner cavity of the left first syringe needle 2 and the inner cavity of the connection tube 9 through the first sealing tube 5 and the second sealing tube 6 of the first module in sequence, and the second capillary tube 8 is installed to communicate the inner cavity of the right second syringe needle 20 and the inner cavity of the connection tube 9 through the second sealing tube 60 and the first sealing tube 50 of the second module in sequence.

The specific use of the microfluidic chip according to the present embodiment is briefly described below.

As shown in fig. 11, the inner phase (e.g., water) first enters the lumen of the left first syringe needle 2, then enters the lumen of the connecting tube 9 through the first capillary tube 7, the first outer phase (e.g., oil) first enters the lumen of the left third syringe needle 4, then enters the lumen of the connecting tube 9 through the second channel 16 of the first module, and the second outer phase (e.g., oil) first enters the lumen of the right third syringe needle 40, then enters the lumen of the connecting tube 9 through the second channel 16 of the second module. In particular, the tapered tip taper of the first capillary 7 provides a droplet generation zone, and the generated droplets enter the lumen of the right second syringe needle 30 through the second capillary 8 and then are expelled through the right second syringe needle 30.

It will be appreciated that this embodiment may form droplets of smaller size than the previous embodiment if the second outer phase is the same as the first outer phase. If the first outer phase is replaced by an intermediate phase, e.g. oil, and the second outer phase is provided as an outer phase, e.g. water, double layer droplets will be generated.

Thus, the microfluidic chip according to the present invention may be further multi-layered nested for preparing multiple emulsions, for example, two modules forming a double emulsion, and three modules forming a triple emulsion, as long as the corresponding capillary is subjected to hydrophobic or oleophobic treatment.

Obviously, according to the microfluidic chip provided by the invention, the syringe needle is easy to connect with the sample injection device, the syringe needle can effectively protect the fragile glass capillary, the manufacturing cost is low, the microfluidic chip is convenient to obtain, and all the components can be assembled and disassembled within two minutes. That is, the invention provides a reconfigurable modularized microfluidic chip which can be freely disassembled or assembled together according to the requirement, can be repeatedly used after being cleaned, and reduces the cost.

In a word, the microfluidic chip is convenient and reliable to assemble, can be disassembled and cleaned and then is reconstructed, and an assembling process is free of adhesives and screw members; only one customized machined part, namely an alignment box, has low machining precision requirement, and a plurality of the customized machined parts can be used in series; the syringe needle has wide selectable range, high compatibility with a sample injection pipeline, and firm and reliable sealing; the reagent has good compatibility, and can be used for preparing micro-droplets with multiple purposes by simply replacing the reagent; the cost is extremely low, and the cost is several yuan.

The foregoing description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention, and various modifications can be made to the above-described embodiment of the present invention. All simple, equivalent changes and modifications made in accordance with the claims and the specification of this application fall within the scope of the patent claims. The present invention is not described in detail in the conventional art.

Claims (10)

1. A microfluidic chip comprising an alignment box, a first syringe needle, a second syringe needle, a third syringe needle, a first gland, a second gland, a first capillary and a second capillary, wherein the first syringe needle and the second syringe needle are connected to the alignment box opposite to each other and define a first channel, the third syringe needle is connected to the alignment box and define a second channel leading to the first channel, the first gland and the second gland are respectively inserted in opposite ends of the first channel in a sealing manner, the first capillary is inserted in the first gland in a sealing manner, the second capillary is inserted in the second gland in a sealing manner, and the conical tip of the first capillary is coaxially aligned with the inner end of the second capillary by means of elastic alignment of the first gland and the second gland to provide a droplet generation area.

2. The microfluidic chip of claim 1, wherein a first capillary communicates with the interior cavity of the first syringe needle and the first channel, a second capillary communicates with the interior cavity of the first channel and the second syringe needle, and a tapered tip of the first capillary is inserted into an inner end of the second capillary directly below the second channel.

3. The microfluidic chip according to claim 1, wherein the alignment box has a box body, a first protruding tube protruding from a left side of the box body, a second protruding tube protruding from a right side of the box body, and a third protruding tube protruding from an upper side of the box body, the first syringe needle cover is connected to and communicates with the first protruding tube, the second syringe needle cover is connected to and communicates with the second protruding tube, and the third syringe needle cover is connected to and communicates with the third protruding tube.

4. The microfluidic chip according to claim 1, wherein the second channel is vertically connected to a middle portion of the first channel to form a T-shaped internal channel.

5. The microfluidic chip according to claim 1, wherein the first or second sealing tube is a silicone or rubber tube.

6. The microfluidic chip of claim 1, comprising two alignment boxes, two first syringe needles, two second syringe needles, two third syringe needles, a first capillary and a second capillary, wherein one first syringe needle, one second syringe needle, one third syringe needle are in communication with one alignment box to provide a first module, and the other first syringe needle, the other second syringe needle, the other third syringe needle are in communication with the other alignment box to provide a second module.

7. The microfluidic chip according to claim 6, further comprising two first sealing tubes, two second sealing tubes, and a connection tube connecting the first module and the second module, wherein the two first sealing tubes and the two second sealing tubes are respectively inserted in opposite ends of the first channel of the first module and the second module in a sealing manner, one end of the connection tube is inserted into the first channel through the second syringe needle and the second sealing tube of the first module and is terminated under the second channel, and the other end of the connection tube is inserted into the first channel through the first syringe needle and the first sealing tube of the second module and is terminated under the second channel.

8. The microfluidic chip according to claim 7, wherein a first capillary tube is installed to communicate with the inner cavity of the first syringe needle of the first module and the inner cavity of the connection tube by passing through the first sealing tube and the second sealing tube of the first module in sequence, and a second capillary tube is installed to communicate with the inner cavity of the second syringe needle of the second module and the inner cavity of the connection tube by passing through the second sealing tube and the first sealing tube of the second module in sequence.

9. A method of preparing droplets using a microfluidic chip according to any one of claims 1 to 8, wherein the inner phase enters the first capillary through the first syringe needle, the outer phase enters the second channel through the third syringe needle, and droplets generated at the tapered tip of the first capillary are discharged through the second capillary and the second syringe needle.

10. The method of claim 9, wherein a plurality of microfluidic chips are nested to produce multiple emulsions.