Liquid electrode-based microfluidic system, microfluidic chip, and preparation method thereof

Abstract

The present invention provides a liquid electrode-based microfluidic system, a microfluidic chip, and a method for preparing the same. The microfluidic system comprises: a dispersed phase transport channel, a first continuous phase channel, a second continuous phase channel, a droplet generation channel, a droplet transport channel, a first electrode channel, and a second electrode channel. The first and second electrode channels are U-shaped channels, symmetrically arranged on either side of the droplet transport channel. When the first and second electrode channels are respectively fed with the first and second conductive solutions, the dispersed phase conductive solutions in the droplet generation channel and the droplet transport channel undergo electrostatic induction with the first and second conductive solutions in the first and second electrode channels, thereby generating charged droplets from the dispersed phase conductive solution. The technical solution of the present invention can improve the charging structure of microfluidic technology and simplify the microfluidic chip manufacturing process.

Description

Technical Field

[0001] The present invention relates to the field of microfluidics, and in particular to a liquid electrode-based microfluidic system, a liquid electrode-based microfluidic chip, and a method for preparing the microfluidic chip. Background Art

[0002] Microfluidics boasts numerous advantages, such as high efficiency, minimal reagent consumption, compact size, and pollution-free properties, enabling the rapid development of droplet microfluidics from its inception. Droplet-based microfluidics represents a promising area of ​​microfluidics, aiming to construct discrete microdroplets from incompatible multiphase fluids. The independent nature of these droplets allows biochemical reactions to proceed within a compartmentalized microfluidic environment. This digital and programmable process provides a platform for addressing challenging research challenges in biochemical medicine.

[0003] Given the advantages of microdroplet technology, such as low reagent consumption, good uniformity, high specific surface area, and independent control, microdroplets have become an important experimental platform in biology, chemistry, medicine, and material preparation applications. Complex biochemical research often involves a series of complex processing processes such as encapsulation, mixing, reaction, and measurement of droplet samples. Precision droplet manipulation technologies such as droplet sorting, splitting, fusion, capture, and release will make these complex processes more convenient and simple. To perform the above operations on droplets, a variety of methods are currently used, such as acoustic-based methods, magnetic-based methods, thermal-based methods, and electrical-based methods. Among them, electrical-based methods have become the most feasible method for droplet manipulation due to their fast response, high controllability, good compatibility, and ease of implementation.

[0004] At present, researchers have used electrophoresis, electrowetting, and electrostatic methods to separate, merge, and efficiently sort droplets based on electrical methods for droplet manipulation. Among them: the electrophoresis method has a simple structure, but the efficiency of droplet manipulation is relatively low, and the dielectrophoretic force generated is also small; the electrowetting method operates on droplets by changing the voltage to change the wettability of the microfluidic chip surface, which has low operating efficiency and is difficult to achieve high-speed and stable droplet manipulation; although the electrostatic method can stably manipulate droplets, the current electrostatic method-related chip has a relatively complex droplet charging structure and requires the setting of special electrodes to contact the droplets, which is difficult to implement. In general, there is no way to achieve the effects of simplicity, efficiency, speed, and pollution-free at the same time in the above droplet manipulation methods.

[0005] Chinese invention patent publication number CN103865795B, published on June 18, 2014, discloses a microfluidic chip for voltage-controlled cell sorting. The chip, which belongs to the field of microfluidic chips, comprises a droplet generator, a charging unit, a voltage control unit, and a droplet collector. The droplet generator comprises a sodium alginate channel and an oil channel perpendicular to the sodium alginate channel. The charging unit comprises a sodium alginate channel and charging electrodes disposed on either side of the sodium alginate channel. The voltage control unit comprises two sodium alginate sub-channels, both connected to the sodium alginate channel with a triangular wedge at the connection point. Charging electrodes are disposed on either side of the two sodium alginate sub-channels, and the sodium alginate sub-channels are connected to an oil injection pipeline before entering the charging electrodes.

[0006] Although this voltage-controlled microfluidic chip for cell sorting provides a structure for independent droplet generation and droplet charging, which can complete droplet generation and charging, it has many shortcomings, specifically the following:

[0007] 1. The droplet charging structure is complex. The droplet chip charging structure is composed of metal thin film electrodes, which requires the preparation of metal electrodes on the substrate, making the preparation process complicated and increasing the difficulty of chip preparation.

[0008] 2. This technical solution adopts contactless charging. When there are two or more droplets in the charging area of ​​the microfluidic chip of this invention patent, it is impossible to complete the charging of a single droplet, the amount of electricity generated is small, the droplet has little charge, and the charging effect is low; and the microfluidic chip is difficult to achieve controllable on-demand charging of a single droplet, and cannot be fully controlled, so that the droplet exhibits positive, negative, and uncharged characteristics.

[0009] 3. In this technical solution, it is difficult to charge a single droplet after the droplet microfluidic chip generates the droplet. The generation of the droplet is separated from the charging structure. When there are two droplets in the area, the charging is done simultaneously, and a single droplet cannot be charged.

[0010] Fourth, this technical solution separates chip charging from droplet generation, and cannot achieve simultaneous completion of droplet generation and droplet charging. The chip structure is very complex. Summary of the Invention

[0011] The technical problem solved by the technical solution of the present invention is how to improve the charging structure of microfluidic technology and simplify the microfluidic chip manufacturing process.

[0012] In order to solve the above technical problems, the technical solution of the present invention provides a microfluidic system based on liquid electrodes, including: a dispersed phase transport channel, a first continuous phase channel and a second continuous phase channel, a droplet generation channel, a droplet transport channel, a first electrode channel and a second electrode channel; the dispersed phase transport channel is suitable for being connected to the dispersed phase inlet to transport a dispersed phase conductive solution; the first continuous phase channel and the second continuous phase channel are suitable for being connected to the first continuous phase inlet and the second continuous phase inlet respectively to transport a first continuous phase fluid and a second continuous phase fluid; the dispersed phase transport channel is suitable for being cross-connected with the first continuous phase channel and the second continuous phase channel to form a cross intersection, and the cross intersection is connected to the droplet generation channel; the dispersed phase conductive solution is suitable for converging with the first continuous phase fluid and the second continuous phase fluid at the cross intersection to enter the droplet generation channel, and the dispersed phase conductive solution is suitable for being connected to the liquid The droplet generation channel is subjected to the shear force of the first continuous phase fluid and the second continuous phase fluid to generate wrapped droplets in the droplet generation channel; the droplet generation channel is suitable for being connected to the droplet delivery channel, and the droplet delivery channel is connected to the droplet collection port; the first electrode channel and the second electrode channel are U-shaped channels, suitable for being symmetrically arranged on both sides of the droplet delivery channel; the first electrode channel is suitable for being connected to the first conductive solution inlet to pass the first conductive solution; the second electrode channel is suitable for being connected to the second conductive solution inlet to pass the first conductive solution; when the first conductive solution and the second conductive solution are passed into the first electrode channel and the second electrode channel respectively, the dispersed phase conductive solution in the droplet generation channel and the droplet delivery channel is suitable for electrostatic induction with the first conductive solution and the second conductive solution in the first electrode channel and the second electrode channel, so that the dispersed phase conductive solution generates charged droplets.

[0013] Optionally, the dispersed phase delivery channel is a first rectangular channel having a width of 50 microns and a depth of 50 microns.

[0014] Optionally, the first continuous phase flow channel and the second continuous phase flow channel are respectively second rectangular flow channels, and the width of the second rectangular flow channel is 60 microns and the depth is 50 microns.

[0015] Optionally, the droplet generation channel is a third rectangular channel having a width of 50 microns, a depth of 50 microns and a length of 50 microns.

[0016] Optionally, the droplet delivery channel is a fourth rectangular channel, and the fourth rectangular channel has a width of 100 microns and a depth of 50 microns.

[0017] Optionally, one end of the first electrode flow channel is suitable for connecting to the first conductive solution inlet, and the other end is suitable for connecting to the first exhaust port; one end of the second electrode flow channel is suitable for connecting to the second conductive solution inlet, and the other end is suitable for connecting to the second exhaust port.

[0018] Optionally, the liquid electrode-based microfluidic system further includes: the dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet, the first conductive solution inlet, the first exhaust port, the second conductive solution inlet, the second exhaust port and the droplet collection port.

[0019] Optionally, the cross intersection is adapted to be connected upwardly to the first continuous phase flow channel, downwardly to the second continuous phase flow channel, leftwardly to the dispersed phase delivery flow channel, and rightwardly to the droplet generation flow channel and the droplet delivery flow channel in sequence;

[0020] The U-shaped ports of the first electrode flow channel and the second electrode flow channel are arranged back to back during configuration; during configuration, the U-shaped bottom of the first electrode flow channel is close to the droplet transport flow channel, and the left flow channel is close to the first continuous phase flow channel; the U-shaped top of the second electrode flow channel is close to the droplet transport flow channel, and the left flow channel is close to the second continuous phase flow channel.

[0021] Optionally, the U-shaped bottom of the first electrode flow channel is set at a distance of 500 microns from the droplet transport flow channel, and the setting distance between the left flow channel and the first continuous phase flow channel is 2 mm; the U-shaped top of the second electrode flow channel is set at a distance of 500 microns from the droplet transport flow channel, and the setting distance between the left flow channel and the second continuous phase flow channel is 2 mm.

[0022] Optionally, the first electrode flow channel and the second electrode flow channel are respectively fifth rectangular flow channels, the width of the fifth rectangular flow channel is 400 microns and the depth is 50 microns; the U-shaped flow channels of the first electrode flow channel and the second electrode flow channel are 100 microns in width and 50 microns in depth.

[0023] In order to solve the above technical problems, the technical solution of the present invention also provides a microfluidic chip based on liquid electrodes, including: a flow channel substrate and a sealing substrate; the flow channel substrate is provided with the microfluidic system based on liquid electrodes as described above, and the sealing substrate is provided with: a dispersed phase joint, a first continuous phase joint, a second continuous phase joint, a first electrode joint, a first electrode exhaust port joint, a second electrode joint, a second electrode exhaust port joint and a droplet collection port joint; the dispersed phase joint, the first continuous phase joint, the second continuous phase joint, the first electrode joint, the first electrode exhaust port joint, the second electrode joint, the second electrode exhaust port joint and the droplet collection port joint are suitable for being coaxially matched and connected with the dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet, the first conductive solution inlet, the first exhaust port, the second conductive solution inlet, the second exhaust port and the droplet collection port of the flow channel substrate when the sealing substrate is bonded to the flow channel substrate.

[0024] Optionally, the flow channel substrate material is PDMS, glass or PMMA; the sealing substrate material is glass or PMMA.

[0025] Optionally, the dispersed phase connector is a conductive connector suitable for connecting to an external dispersed phase electrode to make the dispersed phase conductive solution conductive.

[0026] Optionally, the first electrode connector and the second electrode connector are conductive connectors, respectively suitable for connecting to an external first electrode and an external second electrode to make the first conductive solution and the second conductive solution conductive.

[0027] In order to solve the above technical problems, the technical solution of the present invention further provides a method for preparing a microfluidic chip, comprising:

[0028] A chip positive mold is prepared based on a single crystal silicon wafer to obtain the liquid electrode-based microfluidic system positive mold as described above;

[0029] Performing a static hydrophobic treatment on the male mold of the droplet microfluidic channel system;

[0030] pouring the prepared flow channel substrate material into the microfluidic system male mold to prepare the microfluidic system of the flow channel substrate;

[0031] Cooling the prepared flow channel substrate and cutting and punching the micro-channel system of the flow channel substrate to prepare the desired flow channel substrate;

[0032] The prepared flow channel substrate is used for flow channel packaging to obtain a microfluidic chip.

[0033] Optionally, the method for preparing the microfluidic chip further comprises: cleaning the sealing substrate and performing a surface hydrophilic treatment;

[0034] The flow channel packaging based on the prepared flow channel substrate includes:

[0035] The prepared flow channel substrate is bonded to the sealing substrate to encapsulate the flow channel.

[0036] Optionally, the cleaning of the sealing substrate and performing surface hydrophilic treatment includes:

[0037] The sealing substrate was ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, placed on a hot plate at room temperature, slowly heated to 120° C. and heated for 30 minutes, and dried to obtain a dry sealing substrate;

[0038] The sealed substrate is placed in a plasma cleaning machine for surface activation.

[0039] Optionally, bonding the prepared flow channel substrate to the sealing substrate to form flow channel packaging includes:

[0040] The flow channel substrate and the sealing substrate were placed in acetone, anhydrous ethanol and deionized water in turn, and cleaned in an ultrasonic cleaner for 15 minutes each to remove impurities on the surface of the flow channel substrate and the sealing substrate and keep them clean;

[0041] Place the flow channel substrate into an oxygen plasma cleaning machine and bombard it at a power of 120 W for 2 minutes;

[0042] After the flow channel substrate is bombarded, wait for the pressure in the chamber to rise to atmospheric pressure. Without removing the flow channel substrate, place the sealed substrate into the chamber of the oxygen plasma cleaning machine and bombard it together with the flow channel substrate at a power of 120W for 32 seconds. Then take it out.

[0043] After removing the flow channel substrate and the sealing substrate, add a few drops of anhydrous ethanol as a lubricant to the surfaces to be bonded. This allows the sealing substrate to slide on the flow channel substrate until it is properly aligned. Use a rolling brush to press and align the bonded chips until all bubbles between the flow channel substrate and the sealing substrate are squeezed out.

[0044] The bonded flow channel substrate and the sealing substrate are subjected to enhanced bonding treatment.

[0045] Optionally, the step of performing enhanced bonding treatment on the bonded flow channel substrate and the sealing substrate includes:

[0046] The partially bonded flow channel substrate and sealing substrate are placed in a vacuum drying oven for evacuation to remove the anhydrous ethanol.

[0047] Optionally, the step of performing enhanced bonding treatment on the bonded flow channel substrate and the sealing substrate includes:

[0048] The bonded flow channel substrate and sealing substrate were placed on a heating platform at 95° C. and heated for 24 h.

[0049] Optionally, the method for preparing the microfluidic chip further comprises: before performing the chip positive mold preparation step based on the single crystal silicon wafer, cleaning the single crystal silicon wafer and performing surface hydrophilic treatment.

[0050] Optionally, the cleaning of the single crystal silicon wafer and performing surface hydrophilic treatment includes:

[0051] placing the single crystal silicon wafer in a piranha solution and heating it;

[0052] The heated single crystal silicon wafer was ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, and placed on a hot plate at 120° and heated for 30 minutes to completely dry the single crystal silicon wafer;

[0053] The cleaned single crystal silicon wafer is placed with the surface facing upward in a plasma cleaning machine to complete the cleaning process.

[0054] Optionally, the method for preparing the microfluidic chip further comprises:

[0055] Before the flow channel of the flow channel substrate is packaged, the prepared flow channel substrate is left to stand, rinsed and dried to prepare the flow channel substrate.

[0056] Optionally, the chip positive mold preparation based on a single crystal silicon wafer includes:

[0057] Injecting photoresist at the center of the single crystal silicon wafer and placing the silicon wafer with the photoresist on the chuck of the spin coater, and using the spin coater to spin coat the photoresist;

[0058] The silicon wafer is placed on a heating table for pre-baking, and the mask with the pre-designed droplet microfluidic system is placed on the film frame of the photolithography machine;

[0059] Use a photolithography machine to perform photolithography on silicon wafers;

[0060] After photolithography, the silicon wafer is post-baked and developed, and finally dried with nitrogen, and then placed on a heating table again for hardening and baking to obtain the positive mold of the droplet microfluidic channel system.

[0061] Optionally, the thickness of the positive mold of the droplet microfluidic channel system is 50 microns.

[0062] Optionally, the static hydrophobic treatment of the male mold of the droplet microfluidic channel system includes:

[0063] The obtained positive mold of the microfluidic channel system was placed in a volatile cylinder, and three drops of perfluorodecyltriethylsilane were dripped into the volatile cylinder. After sealing, the volatile cylinder was placed in an oven for heating and baking.

[0064] Optionally, the step of pouring the prepared flow channel substrate material into the microfluidic system male mold to prepare the microfluidic system of the flow channel substrate includes:

[0065] The PDMS prepolymer and curing agent were evenly mixed in a weight ratio of 10:1, stirred evenly, and then placed in a vacuum drying oven for degassing for 30 minutes;

[0066] A certain amount of PDMS was drawn up by a syringe and poured onto the positive template of the microfluidic system, and then placed in a vacuum drying oven for degassing for 30 minutes, and then placed on a heating table for heating and curing to prepare a microfluidic system of the flow channel substrate.

[0067] The beneficial effects of the technical solution of the present invention include at least:

[0068] The microfluidic system and microfluidic chip provided by the technical solution of the present invention use liquid electrodes, which have a relatively simple structure. The liquid electrodes can be used to generate droplets and charge the droplets simultaneously, which greatly simplifies the preparation process of the droplet charging microfluidic chip, provides an efficient operation method for droplet microfluidics, and greatly improves the efficiency of manufacturing and use.

[0069] The microfluidic chip provided by the technical solution of the present invention can be charged on demand after generating droplets, so that the generated droplets can have charges on the surface; the technical solution of the present invention can greatly enhance the operability of droplet-type microfluidic chips, and greatly enhance the operability of droplet microfluidic chips for droplet splitting, deflection, movement, fusion, etc.

[0070] The technical solution of the present invention can make the droplets generated by the droplet microfluidic chip positively charged, negatively charged or uncharged as needed; it further realizes charging the droplets on demand while the droplets are generated, making related droplet products more practical; the technical solution of the present invention can realize droplet generation and droplet charging at the same time, simplifying the chip structure; it further simplifies the chip preparation process; the technical solution of the present invention can realize charging of droplets without the need for additional arrangement of electrodes, optimizing the technical solution of the microfluidic chip to realize droplet charging. BRIEF DESCRIPTION OF THE DRAWINGS

[0071] Other features, objects and advantages of the present invention will become more apparent upon reading the detailed description of non-limiting embodiments with reference to the following drawings:

[0072] Figure 1-1 A schematic structural diagram of a microfluidic system provided by the technical solution of the present invention;

[0073] Figure 1-2 Provides a schematic diagram of the depth of the rectangular flow channel and the electrode flow channel for the technical solution of the present invention;

[0074] Figure 2A schematic diagram of the working state of the microfluidic system provided by the technical solution of the present invention when it is powered on;

[0075] Figure 3 A schematic diagram of a microfluidic system connector structure provided by the technical solution of the present invention;

[0076] Figure 4 A schematic structural diagram of a microfluidic chip provided by the technical solution of the present invention;

[0077] Figure 5 A schematic flow chart of the steps of a method for preparing a microfluidic chip provided by the technical solution of the present invention. DETAILED DESCRIPTION

[0078] In order to better illustrate the technical solution of the present invention, the present invention will be further described below with reference to the accompanying drawings.

[0079] Example 1

[0080] like Figure 1-1 The illustrated liquid-electrode-based microfluidic system can be installed on the flow channel substrate of a microfluidic chip and includes a dispersed-phase delivery channel 1, a continuous-phase flow channel 2, a continuous-phase flow channel 6, a droplet generation channel 7, a droplet delivery channel 8, an electrode flow channel 5, and an electrode flow channel 9. Dispersed-phase delivery channel 1 can be connected to the dispersed-phase inlet of the microfluidic chip to deliver a dispersed-phase conductive solution. Continuous-phase flow channel 2 and continuous-phase flow channel 6 can each be connected to the continuous-phase inlet of the microfluidic chip to deliver the corresponding continuous-phase fluid.

[0081] Continue to refer Figure 1-1 In the microfluidic system of the technical solution of the present invention, the dispersed phase transport flow 1 is cross-connected with the continuous phase flow channel 2 and the continuous phase flow channel 6 to form a cross intersection. Figure 1-1 The cross is connected to the droplet generation channel 7.

[0082] Therefore, in the technical solution of the present invention, the dispersed phase conveying flow 1, the continuous phase flow channel 2, the continuous phase flow channel 6 and the droplet generation flow channel 7 are cross-intersected. Figure 1-1 In the direction, the dispersed phase conveying flow 1 and the droplet generation flow channel 7 are arranged opposite to each other on the left and right sides of the cross intersection, and the continuous phase flow channel 2 and the continuous phase flow channel 6 are arranged opposite to each other on the upper and lower sides of the cross intersection.

[0083] Continue to refer Figure 1-1 A dispersed phase conductive solution is introduced into the dispersed phase transport flow 1, and the dispersed phase conductive solution is suitable for intersecting with the continuous phase fluid in the continuous phase flow channel 2 and the continuous phase flow channel 6 at the cross intersection to enter the droplet generation flow channel. Figure 1-1Figure 2 illustrates the flow direction a of the dispersed-phase conductive solution, the flow direction b of the continuous-phase fluid in continuous-phase channel 2, and the flow direction c of the continuous-phase fluid in continuous-phase channel 6. The dispersed-phase conductive solution in the droplet generation channel is subjected to shear forces from the continuous-phase fluid in directions b and c, as well as its own surface tension, causing it to break apart and produce encapsulated droplets.

[0084] Continue to refer Figure 1-1 The droplet generation channel 7 can be connected to the droplet delivery channel 8. The droplet delivery channel 8 is connected to the droplet collection port. The droplet collection port can be provided on the microfluidic chip or configured at the port of the droplet delivery channel 8. The droplet collection end can be connected to the droplet collection port of the microfluidic chip. Specifically, the port of the droplet delivery channel 8 can be radially divided into multiple separation channels, and the multiple separation channels are suitable for being respectively connected to the droplet collection ports of multiple microfluidic chips.

[0085] Continue to refer Figure 1-1 The electrode flow channel 5 and the electrode flow channel 9 are U-shaped flow channels symmetrically arranged on both sides of the droplet delivery flow channel 8. Both of the U-shaped flow channels have two flow channel ports, one flow channel port is a conductive solution port, and the other flow channel port is an exhaust port.

[0086] In the microfluidic system of the technical solution of the present invention, liquid electrodes are used. The conductive solution ports of the electrode flow channels 5 and 9 can be connected to the conductive solution inlet of the microfluidic chip, allowing the conductive solution to be introduced into the electrode flow channels 5 and 9. At the same time, the exhaust ports of the electrode flow channels 5 and 9 can be connected to the electrode exhaust ports of the microfluidic chip. When the conductive solution is introduced into the conductive solution ports of the electrode flow channels 5 and 9, the electrode flow channels are energized, inducing a charge in the current-carrying fluid in the dispersed phase flow channel, thereby charging the droplets produced by the droplet generation flow channel 7.

[0087] More specifically, the liquid electrode formed by the electrode flow channel 5 and the electrode flow channel 9 can charge the droplets of the dispersed phase conductive solution. Figure 2 , Figure 2 The microfluidic system of the present invention is shown as being energized when in use. Figure 2 As shown, the dispersed phase conductive solution is grounded), and the electrode flow channel 5 and the electrode flow channel 9 can be fed with a conductive solution when used as needed, and the liquid electrode formed can be connected to a positive or negative charge (such as Figure 2 The liquid electrode formed by the electrode flow channel 5 and the electrode flow channel 9 is connected to positive pressure or negative pressure):

[0088] When the liquid electrode is negatively charged, the liquid electrode and the droplets in the dispersed conductive solution undergo electrostatic induction, generating positive charges on the surface of the dispersed conductive solution. At this time, the generated droplets will be positively charged, forming Figure 1-1Medium positively charged droplet (4);

[0089] When the charging electrode is positively charged, the liquid electrode and the droplets in the dispersed conductive solution undergo electrostatic induction, generating negative charges on the surface of the dispersed conductive solution. At this time, the droplets generated will be negatively charged, forming Figure 1-1 The negatively charged droplet (3).

[0090] When the microfluidic chip is powered on and working, the microfluidic system of the technical solution of the present invention is adopted. Since the electrode flow channel 5 and the electrode flow channel 9 are liquid electrodes and work simultaneously with the droplet generation in the cross structure when powered on, the microfluidic system of the technical solution of the present invention can achieve the technical effect of simultaneous droplet generation and droplet charging.

[0091] The description of the above-mentioned cross intersection of the microfluidic channel system in this embodiment in the up, down, left and right directions is relative, that is, based on the cross intersection being connected to the continuous phase flow channel 6 upward, connected to the continuous phase flow channel 2 downward, connected to the dispersed phase transport flow channel 1 to the left, and connected to the droplet generation flow channel 7 and the droplet transport flow channel 8 to the right in sequence.

[0092] The U-shaped ports of the electrode flow channel 5 and the electrode flow channel 9 are arranged back to back during configuration; during configuration, the U-shaped bottom of the electrode flow channel 9 is arranged close to the droplet transport flow channel 8, and the left flow channel is arranged close to the continuous phase flow channel 6; the U-shaped top of the electrode flow channel 5 is arranged close to the droplet transport flow channel 8, and the left flow channel is arranged close to the continuous phase flow channel 2.

[0093] In this embodiment, the corresponding flow channel system can also be configured according to the following sizes and shapes:

[0094] Combine Figure 1-1 The distance S1 between the U-shaped bottom of the electrode flow channel 9 and the droplet delivery channel 8 is 500 microns, and the distance S2 between the left flow channel and the continuous phase flow channel 6 is 2 mm. Similarly, the distance S3 between the U-shaped top of the electrode flow channel 5 and the droplet delivery channel 8 is 500 microns, and the distance S4 between the left flow channel and the continuous phase flow channel 2 is 2 mm.

[0095] More specifically, the dispersed phase transport channel 1 is a rectangular channel, which can be 50 microns wide and 50 microns deep. The continuous phase channel 2 and the continuous phase channel 6 are rectangular channels, respectively, which can be 60 microns wide and 50 microns deep. The droplet generation channel 7 is a rectangular channel, which has a width of 50 microns, a depth of 50 microns and a length of 50 microns. The droplet transport channel 8 is a rectangular channel, which has a width of 100 microns and a depth of 50 microns. The electrode channel 5 and the electrode channel 9 are rectangular channels, respectively, which have a width of 400 microns and a depth of 50 microns; the U-shaped channels of the electrode channel 5 and the electrode channel 9 are 100 microns wide and 50 microns deep. This embodiment does not limit the lengths of the dispersed phase transport channel 1, the continuous phase channel 2, the continuous phase channel 6, and the droplet transport channel 8.

[0096] It should be noted that:

[0097] The size and shape of the microfluidic system are set as the preferred examples provided in this embodiment. In other embodiments, other sizes can also be configured as needed.

[0098] The width of the rectangular flow channel refers to Figure 1-1 The width of the channel is shown in the figure, for example, the width k1 of the channel shown in the dispersed phase transport channel 1. The depth of the rectangular channel refers to Figure 1-1 The etching depth of the middle channel on the channel substrate (the depth of the rectangular channel is detailed in Figure 1-2 The depth of the electrode channel also refers to the depth of the electrode channel. Figure 1-1 The etching depth of the middle electrode channel on the channel substrate (see the depth of the electrode channel for details) Figure 1-2 The length of the droplet generation channel 7 is the depth of the electrode flow channel shown in FIG. Figure 1-1 The flow channel length k2 in.

[0099] Example 2

[0100] like Figure 3 The microfluidic system shown includes: a dispersed phase delivery channel 108, a continuous phase flow channel 110, a continuous phase flow channel 109, a droplet generation channel 111, a droplet delivery channel 112, an electrode flow channel 114, and an electrode flow channel 113. The connection structure and function of the dispersed phase delivery channel 108, the continuous phase flow channel 110, the continuous phase flow channel 109, the droplet generation channel 111, the droplet delivery channel 112, the electrode flow channel 114, and the electrode flow channel 113 are similar to those shown in FIG. Figure 1-1 The dispersed phase transport channel 1, continuous phase channel 2, continuous phase channel 6, droplet generation channel 7, droplet transport channel 8, electrode channel 5 and electrode channel 9 described in the first embodiment are consistent.

[0101] In addition to the above structure, Figure 3The microfluidic system shown further includes the following components located on the channel substrate: a dispersed phase inlet 101 , a continuous phase inlet 103 , a continuous phase inlet 102 , a conductive solution inlet 104 , an exhaust port 105 , a conductive solution inlet 106 , an exhaust port 107 and a droplet collection port 115 .

[0102] Specific, combined Figure 3 One end of the dispersed phase transport channel 108 is connected to the dispersed phase inlet 101, and the other end is connected to the cross intersection (not shown in the figure); one end of the continuous phase channel 110 is connected to the continuous phase inlet 103, and the other end is connected to the cross intersection; one end of the continuous phase channel 109 is connected to the continuous phase inlet 102, and the other end is continuously connected to the cross intersection; one end of the droplet generation channel 111 is connected to the cross intersection, and the other end is connected to the droplet transport channel 112; one end of the droplet transport channel 112 is connected to the droplet generation channel 111, and the other end is connected to the droplet collection port 115; one end of the electrode channel 114 is connected to the conductive solution inlet 106, and the other end is connected to the exhaust port 107; one end of the electrode channel 113 is connected to the conductive solution inlet 104, and the other end is connected to the exhaust port 105.

[0103] In this embodiment, the microfluidic system includes not only the flow channel system of the flow channel substrate, but also the flow channel interface. In other embodiments, the flow channel interface can be configured as needed. This embodiment is not limited thereto.

[0104] Example 3

[0105] This embodiment provides a microfluidic chip based on liquid electrodes, which can simultaneously realize droplet generation and droplet charging. Figure 3 As shown, it is made of a flow channel substrate and a sealing substrate bonded together, and the flow channel inlet of the chip is connected to the corresponding connector.

[0106] The channel substrate is provided with a microfluidic system as described in Example 2, including: a dispersed phase transport channel 108, a continuous phase channel 110, a continuous phase channel 109, a droplet generation channel 111, a droplet transport channel 112, an electrode channel 114, an electrode channel 113, as well as a dispersed phase inlet 101, a continuous phase inlet 103, a continuous phase inlet 102, a conductive solution inlet 104, an exhaust port 105, a conductive solution inlet 106, an exhaust port 107 and a droplet collection port 115.

[0107] The sealed substrate is provided with: dispersed phase joint 201, continuous phase joint 202, continuous phase joint 203, electrode joint 204, electrode exhaust port joint 205, electrode joint 206, electrode exhaust port joint 207 and droplet collection port joint 208.

[0108] For details, please refer to Figure 4The dispersed phase connector 201 on the sealing substrate is coaxially matched with the dispersed phase inlet 101 of the dispersed phase delivery channel 108 and connected through; the continuous phase connector 202 is coaxially matched with the continuous phase inlet 103 of the continuous phase channel 110 and connected through; the continuous phase connector 203 is coaxially matched with the continuous phase inlet 102 of the continuous phase channel 109 and connected through; the electrode connector 204 and the electrode exhaust port connector 205 are respectively located at both ends of the electrode channel 113, and the electrode connector 204 is coaxially matched with the conductive solution inlet 104 of the electrode channel 113 and connected The electrode exhaust port connector 205 is coaxially matched with the exhaust port 105 of the electrode flow channel 113 and is connected through; the electrode connector 206 and the electrode exhaust port connector 207 are respectively located at both ends of the electrode flow channel 114, the electrode connector 206 is coaxially matched with the conductive solution inlet 106 of the electrode flow channel 114 and is connected through, and the electrode exhaust port connector 207 is coaxially matched with the exhaust port 107 of the electrode flow channel 114 and is connected through; the droplet collection port connector 208 is coaxially matched with the droplet collection port 115 connected to the droplet transport flow channel 112 and is connected through.

[0109] In this embodiment, the flow channel substrate material for making the microfluidic chip can be PDMS (polydimethylsiloxane), glass or PMMA (polymethyl methacrylate). The sealing substrate material can also be glass or PMMA.

[0110] Figure 4 Dispersed-phase connector 201 is a conductive connector suitable for connecting to an external dispersed-phase electrode to allow the dispersed-phase conductive solution introduced into the dispersed-phase delivery channel of the present invention to conduct electricity when energized. Specifically, dispersed-phase connector 201 can be made of a conductive metal such as aluminum or copper, or a conductive non-metallic material such as carbon nanotubes or conductive ceramics. When dispersed-phase connector 201 is connected to an external electrode and the electrode is energized, the conductive fluid in dispersed-phase delivery channel 108 becomes conductive and undergoes electrostatic induction with the conductive fluid in the charging channels (electrode channels 114 and 113).

[0111] Correspondingly, electrode connector 204 and electrode connector 206 are also conductive connectors, each suitable for connecting to an external control electrode to make the conductive solution in the liquid electrode conductive when powered, so that the resulting liquid electrode is positively or negatively charged. The material of electrode connector 204 and electrode connector 206 can be a conductive metal material such as aluminum, copper, etc., or a conductive non-metallic material such as carbon tubes, conductive ceramics, etc. When electrode connector 204 and electrode connector 206 are connected to the external control electrode and the control electrode is powered, the conductive fluid in electrode flow channel 114 and electrode flow channel 113 will become conductive (positively or negatively charged) and charge the droplets in droplet generation flow channel 111, that is, perform corresponding electrostatic induction with the conductive fluid in electrode flow channel 114 and electrode flow channel 113.

[0112] Example 4

[0113] Based on Example 3, this embodiment also provides a method for preparing a microfluidic chip, such as Figure 5 The following steps are shown:

[0114] Step S100 , preparing a chip positive mold based on a single crystal silicon wafer to obtain a droplet microfluidic system positive mold.

[0115] The droplet microfluidic channel system male mold in step S100 may be the droplet microfluidic channel system described in the first or second embodiment.

[0116] In step S100, before preparing the chip positive mold for the single crystal silicon wafer, the single crystal silicon wafer may be cleaned and subjected to surface hydrophilic treatment. The specific process may be:

[0117] placing the single crystal silicon wafer in a piranha solution and heating it;

[0118] The heated single crystal silicon wafer was ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, and placed on a hot plate at 120° and heated for 30 minutes to completely dry the single crystal silicon wafer;

[0119] The cleaned single crystal silicon wafer is placed with the surface facing upward in a plasma cleaning machine to complete the cleaning process.

[0120] More specifically, in step S100, a chip positive mold can be prepared using a single crystal silicon wafer through the following steps:

[0121] Injecting photoresist at the center of the single crystal silicon wafer and placing the silicon wafer with the photoresist on the chuck of the spin coater, and using the spin coater to spin coat the photoresist;

[0122] The silicon wafer is placed on a heating table for pre-baking, and the mask with the pre-designed droplet microfluidic system is placed on the film frame of the photolithography machine;

[0123] Use a photolithography machine to perform photolithography on silicon wafers;

[0124] After photolithography, the silicon wafer is post-baked and developed, and finally dried with nitrogen, and then placed on a heating table again for hardening and baking to obtain the positive mold of the droplet microfluidic channel system.

[0125] The mask with the pre-designed droplet microfluidic system referred to in the above steps may be the pre-designed droplet microfluidic system mask described in the second embodiment.

[0126] The thickness of the male mold of the droplet microfluidic channel system in this embodiment can be 50 microns.

[0127] Step S101 , subjecting the male mold of the droplet microfluidic channel system to a static hydrophobic treatment.

[0128] In step S101, the positive mold of the droplet microfluidic channel system can be subjected to static hydrophobic treatment by the following process: the obtained positive mold of the microfluidic channel system is placed in a volatile cylinder, three drops of perfluorodecyltriethylsilane are dripped into the volatile cylinder, and after sealing, the volatile cylinder is placed in an oven for heating and baking.

[0129] Step S102 , pouring the prepared material of the flow channel substrate into a positive mold of the microfluidic system to prepare the microfluidic system of the flow channel substrate.

[0130] In step S102, the prepared channel substrate material can be poured into the positive mold of the microfluidic system by the following steps:

[0131] The PDMS prepolymer and curing agent were evenly mixed in a weight ratio of 10:1, stirred evenly, and then placed in a vacuum drying oven for degassing for 30 minutes;

[0132] A certain amount of PDMS was drawn up by a syringe and poured onto the positive template of the microfluidic system, and then placed in a vacuum drying oven for degassing for 30 minutes, and then placed on a heating table for heating and curing to prepare a microfluidic system of the flow channel substrate.

[0133] The material for preparing the flow channel substrate can be the materials mentioned in the above embodiments: PDMS, glass or PMMA.

[0134] Step S103 , cooling the prepared flow channel substrate and cutting and punching the micro-channel system of the flow channel substrate to obtain the desired flow channel substrate.

[0135] Step S104 , performing channel packaging based on the prepared channel substrate to obtain a microfluidic chip.

[0136] In step S104 , the sealing substrate may be cleaned in advance, and the surface of the sealing substrate may be subjected to a hydrophilic treatment, and the prepared flow channel substrate may be bonded to the sealing substrate to achieve flow channel packaging.

[0137] The flow channel substrate preferably adopts the positive mold of the micro-channel system of embodiment 2, and the sealing substrate can adopt the joint structure of embodiment 3 to cooperate with the flow channel substrate for packaging. The sealing substrate can specifically be a glass substrate or a PMMA substrate.

[0138] The following steps can be used to clean the sealed substrate and perform surface hydrophilic treatment:

[0139] The sealing substrate was ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, placed on a hot plate at room temperature, slowly heated to 120° C. and heated for 30 minutes, and dried to obtain a dry sealing substrate;

[0140] The sealed substrate is placed in a plasma cleaning machine for surface activation.

[0141] The prepared flow channel substrate can be bonded to the sealing substrate to form a flow channel package using the following steps:

[0142] The flow channel substrate and the sealing substrate were placed in acetone, anhydrous ethanol and deionized water in turn, and cleaned in an ultrasonic cleaner for 15 minutes each to remove impurities on the surface of the flow channel substrate and the sealing substrate and keep them clean;

[0143] Place the flow channel substrate into an oxygen plasma cleaning machine and bombard it at a power of 120 W for 2 minutes;

[0144] After the flow channel substrate is bombarded, wait for the pressure in the chamber to rise to atmospheric pressure. Without removing the flow channel substrate, place the sealed substrate into the chamber of the oxygen plasma cleaning machine and bombard it together with the flow channel substrate at a power of 120W for 32 seconds. Then take it out.

[0145] After removing the flow channel substrate and the sealing substrate, add a few drops of anhydrous ethanol as a lubricant to the surfaces to be bonded. This allows the sealing substrate to slide on the flow channel substrate until it is properly aligned. Use a rolling brush to press and align the bonded chips until all bubbles between the flow channel substrate and the sealing substrate are squeezed out.

[0146] The bonded flow channel substrate and the sealing substrate are subjected to enhanced bonding treatment.

[0147] The following two methods can be used to enhance the bonding between the flow channel substrate and the sealing substrate after bonding, specifically:

[0148] Place the partially bonded flow channel substrate and sealing substrate into a vacuum drying oven for evacuation to remove the anhydrous ethanol; or

[0149] The bonded flow channel substrate and sealing substrate were placed on a heating platform at 95° C. and heated for 24 h.

[0150] Before executing step S104, the flow channel substrate prepared in step S103 may be allowed to stand, rinsed, and dried to obtain the flow channel substrate (also referred to as a flow channel base).

[0151] Application Examples

[0152] Based on the application example of the fourth embodiment, the preparation method of the microfluidic chip of this application example includes:

[0153] A glass substrate and a single crystal silicon wafer are cleaned and subjected to surface hydrophilic treatment;

[0154] The glass substrate is used for flow channel packaging;

[0155] A chip positive mold is prepared based on the single crystal silicon wafer to obtain a microfluidic system positive mold (the microfluidic system positive mold is based on the microfluidic system described in Example 2);

[0156] Performing a hydrophobic treatment on the positive mold of the microfluidic channel system;

[0157] pouring the PDMS material for preparing the flow channel substrate into the positive mold of the microfluidic system to prepare the PDMS microfluidic system;

[0158] Cooling the PDMS microfluidic system and cutting and punching the microfluidic system to prepare a PDMS substrate;

[0159] The glass substrate with external electrodes (the glass substrate has the joint structures on the sealing substrate referred to in Example 3 and the external electrodes / control electrodes to which the joints are connected when powered) is allowed to stand, rinsed, and dried to prepare the glass base;

[0160] The glass substrate was bonded to the PDMS substrate.

[0161] Optionally, the glass substrate is cleaned according to the following steps: the glass substrate is ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, placed on a hot plate at room temperature, slowly heated to 120°C and heated for 30 minutes, and dried to obtain a dry glass substrate.

[0162] Specifically:

[0163] The surface hydrophilic treatment of the glass substrate can be performed according to the following steps: the glass substrate is placed in a plasma cleaning machine for surface activation.

[0164] The following steps can be used to clean single crystal silicon wafers:

[0165] placing the single crystal silicon wafer in a piranha solution and heating it;

[0166] The heated single crystal silicon wafer was ultrasonically cleaned with acetone, anhydrous ethanol and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, and placed on a hot plate at 120° and heated for 30 minutes to completely dry the single crystal silicon wafer.

[0167] The surface hydrophilic treatment of the single crystal silicon wafer can be carried out as follows: Place the cleaned single crystal silicon wafer with the surface facing up in a plasma cleaning machine to complete the cleaning process.

[0168] The preparation of a chip positive mold based on the single crystal silicon wafer includes:

[0169] Inject the photoresist into the center of the single crystal silicon wafer and place the silicon wafer with the photoresist on the chuck of the spin coater, and use the spin coater to spin coat the photoresist;

[0170] Place the silicon wafer on a heating table for pre-baking, and place the mask with a pre-designed flow channel system on the lithography machine's film-curing rack;

[0171] Use a photolithography machine to perform photolithography on silicon wafers;

[0172] After photolithography, the silicon wafer is post-baked and developed, and finally dried with nitrogen. It is then placed on a heating table again for hardening and baking to obtain a chip positive mold.

[0173] The microfluidic system male mold can be hydrophobized by the following process:

[0174] The obtained positive mold of the microfluidic channel system was placed in a volatile cylinder, and three drops of perfluorodecyltriethylsilane were dripped into the volatile cylinder. After sealing, the volatile cylinder was placed in an oven for heating and baking.

[0175] The prepared PDMS material can be cast into the positive mold of the microfluidic system to prepare the PDMS microfluidic system through the following process:

[0176] The PDMS prepolymer and the curing agent were uniformly mixed in a weight ratio of 10:1, stirred evenly, and placed in a vacuum drying oven for degassing for 30 minutes. Then, a certain amount of PDMS was drawn with a syringe and poured onto the positive template of the microfluidic system. The mixture was placed in a vacuum drying oven for degassing for 30 minutes, and then placed on a heating table for heating and curing. Finally, the PDMS microfluidic system was prepared.

[0177] The glass substrate can be bonded to the PDMS substrate by the following steps:

[0178] Place the glass substrate and PDMS in acetone, anhydrous ethanol, and deionized water in sequence, and clean them in an ultrasonic cleaner for 15 minutes each to remove impurities on the surface of the glass substrate and PDMS and keep them clean;

[0179] The glass substrate was placed in an oxygen plasma cleaning machine and bombarded at a power of 120 W for 2 min;

[0180] After the glass substrate was bombarded, the pressure in the chamber was allowed to rise to atmospheric pressure. Without removing the glass substrate, the PDMS was placed in the chamber of an oxygen plasma cleaning machine and bombarded together with the glass substrate at a power of 120 W for 32 seconds before being removed.

[0181] After removing the glass substrate and PDMS, add a few drops of anhydrous ethanol as a lubricant to the surfaces to be bonded. This allows the PDMS to slide on the glass substrate until it is properly aligned. Use a roller brush to press and align the bonded chip until all bubbles between the glass substrate and PDMS are squeezed out.

[0182] Then, the partially bonded glass substrate and PDMS were placed in a vacuum drying oven for evacuation to remove anhydrous ethanol and enhance the bonding degree.

[0183] Alternatively, the bonded glass substrate and PDMS substrate may be placed on a heating platform at 95° C. and heated for 24 hours to enhance the bonding strength between the glass substrate and PDMS.

[0184] The above describes the specific embodiments of the present invention. It should be understood that the present invention is not limited to the above specific embodiments, and those skilled in the art may make various variations or modifications within the scope of the claims, which do not affect the essence of the present invention.

Claims

1. A microfluidic system based on liquid electrodes, characterized in that: include: Dispersed phase transport flow channel, first continuous phase flow channel and second continuous phase flow channel, droplet generation flow channel, droplet transport flow channel, first electrode flow channel and second electrode flow channel; The dispersed phase delivery channel is suitable for connecting to the dispersed phase inlet to deliver the dispersed phase conductive solution; The first continuous phase flow channel and the second continuous phase flow channel are suitable for connecting to the first continuous phase inlet and the second continuous phase inlet respectively to transport the first continuous phase fluid and the second continuous phase fluid; The dispersed phase delivery channel is adapted to cross-connect with the first continuous phase channel and the second continuous phase channel to form a cross intersection, and the cross intersection is connected to the droplet generation channel; The dispersed-phase conductive solution is suitable for intersecting with the first continuous-phase fluid and the second continuous-phase fluid at the intersection to enter the droplet generation channel, and the dispersed-phase conductive solution is suitable for being subjected to shear forces of the first continuous-phase fluid and the second continuous-phase fluid in the droplet generation channel to generate enclosed droplets in the droplet generation channel; The droplet generation channel is adapted to be connected to the droplet delivery channel, and the droplet delivery channel is connected to the droplet collection port; The first electrode flow channel and the second electrode flow channel are U-shaped flow channels, adapted to be symmetrically arranged on both sides of the droplet delivery flow channel; the first electrode flow channel is adapted to be connected to the first conductive solution inlet to allow the first conductive solution to flow into the first conductive solution; The second electrode flow channel is suitable for connecting to a second conductive solution inlet to allow the second conductive solution to flow into the second electrode flow channel; When the first conductive solution and the second conductive solution are respectively introduced into the first electrode flow channel and the second electrode flow channel, the dispersed phase conductive solution in the droplet generation flow channel and the droplet transport flow channel is suitable for electrostatic induction with the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel, so that the dispersed phase conductive solution generates charged droplets.

2. The liquid electrode-based microfluidic system according to claim 1, wherein: The dispersed phase delivery channel is a first rectangular channel, and the width and depth of the first rectangular channel are 50 microns and 50 microns, respectively.

3. The liquid electrode-based microfluidic system according to claim 1, wherein: The first continuous phase flow channel and the second continuous phase flow channel are respectively second rectangular flow channels, and the width of the second rectangular flow channel is 60 microns and the depth is 50 microns.

4. The liquid electrode-based microfluidic system according to claim 1, wherein: The droplet generation channel is a third rectangular channel having a width of 50 microns, a depth of 50 microns, and a length of 50 microns.

5. The liquid electrode-based microfluidic system according to claim 1, wherein: The droplet delivery channel is a fourth rectangular channel, and the width of the fourth rectangular channel is 100 microns and the depth is 50 microns.

6. The liquid electrode-based microfluidic system according to claim 1, wherein: One end of the first electrode flow channel is suitable for connecting to the first conductive solution inlet, and the other end is suitable for connecting to the first exhaust port; one end of the second electrode flow channel is suitable for connecting to the second conductive solution inlet, and the other end is suitable for connecting to the second exhaust port.

7. The liquid electrode-based microfluidic system according to claim 6, wherein: Also includes: The dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet, the first conductive solution inlet, the first exhaust port, the second conductive solution inlet, the second exhaust port and the droplet collection port.

8. The liquid electrode-based microfluidic system according to any one of claims 1 to 7, wherein: The cross intersection is suitable for connecting upward to the first continuous phase flow channel, downward to the second continuous phase flow channel, leftward to the dispersed phase delivery flow channel, and rightward to the droplet generation flow channel and the droplet delivery flow channel in sequence; The U-shaped ports of the first electrode flow channel and the second electrode flow channel are arranged back to back during configuration; during configuration, the U-shaped bottom of the first electrode flow channel is close to the droplet transport flow channel, and the left flow channel is close to the first continuous phase flow channel; the U-shaped top of the second electrode flow channel is close to the droplet transport flow channel, and the left flow channel is close to the second continuous phase flow channel.

9. The liquid electrode-based microfluidic system according to claim 8, wherein: The U-shaped bottom of the first electrode flow channel is set at a distance of 500 microns from the droplet transport flow channel, and the setting distance between the left flow channel and the first continuous phase flow channel is 2 mm; the U-shaped top of the second electrode flow channel is set at a distance of 500 microns from the droplet transport flow channel, and the setting distance between the left flow channel and the second continuous phase flow channel is 2 mm.

10. The liquid electrode-based microfluidic system according to claim 1, wherein: The first electrode flow channel and the second electrode flow channel are respectively fifth rectangular flow channels, the width of the fifth rectangular flow channel is 400 microns and the depth is 50 microns; the U-shaped flow channels of the first electrode flow channel and the second electrode flow channel are 100 microns in width and 50 microns in depth.

11. A liquid electrode-based microfluidic chip, comprising: A flow channel substrate and a sealing substrate, characterized in that the flow channel substrate is provided with a liquid electrode-based microfluidic system as described in any one of claims 1 to 10, and the sealing substrate is provided with: a dispersed phase connector, a first continuous phase connector, a second continuous phase connector, a first electrode connector, a first electrode exhaust port connector, a second electrode connector, a second electrode exhaust port connector and a droplet collection port connector; the dispersed phase connector, the first continuous phase connector, the second continuous phase connector, the first electrode connector, the first electrode exhaust port connector, the second electrode connector, the second electrode exhaust port connector and the droplet collection port connector are suitable for correspondingly coaxially matching and connecting with the dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet, the first conductive solution inlet, the first exhaust port, the second conductive solution inlet, the second exhaust port and the droplet collection port of the flow channel substrate when the sealing substrate is bonded to the flow channel substrate.

12. The liquid electrode-based microfluidic chip according to claim 11, wherein: The flow channel substrate material is PDMS, glass or PMMA; the sealing substrate material is glass or PMMA.

13. The liquid electrode-based microfluidic chip according to claim 11, wherein: The dispersed phase connector is a conductive connector suitable for connecting with an external dispersed phase electrode to make the dispersed phase conductive solution conductive.

14. The liquid electrode-based microfluidic chip according to claim 11, wherein: The first electrode connector and the second electrode connector are conductive connectors, respectively suitable for connecting to an external first electrode and an external second electrode to make the first conductive solution and the second conductive solution conductive.

15. A method for preparing a microfluidic chip, characterized in that: include: Prepare a chip positive mold based on a single crystal silicon wafer to obtain a positive mold of a liquid electrode-based microfluidic system according to any one of claims 1 to 10; Performing a hydrophobic treatment on the male mold of the liquid electrode-based microfluidic channel system; Casting the prepared flow channel substrate material on the positive mold of the liquid electrode-based microfluidic system to prepare the microfluidic system of the flow channel substrate; Cooling the prepared flow channel substrate and cutting and punching the micro-channel system of the flow channel substrate to prepare the desired flow channel substrate; The prepared flow channel substrate is used for flow channel packaging to obtain a microfluidic chip.

16. The method for preparing a microfluidic chip according to claim 15, wherein: Also includes: Cleaning the sealed substrate and performing surface hydrophilic treatment; The flow channel packaging based on the prepared flow channel substrate includes: The prepared flow channel substrate is bonded to the sealing substrate to encapsulate the flow channel.

17. The method for preparing a microfluidic chip according to claim 16, wherein: The cleaning and surface hydrophilic treatment of the sealing substrate comprises: The sealing substrate was ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, placed on a hot plate at room temperature, slowly heated to 120° C. and heated for 30 minutes, and dried to obtain a dry sealing substrate; The sealed substrate is placed in a plasma cleaning machine for surface activation.

18. The method for preparing a microfluidic chip according to claim 16, wherein: The step of bonding the prepared flow channel substrate to the sealing substrate to form a flow channel package comprises: The flow channel substrate and the sealing substrate were placed in acetone, anhydrous ethanol and deionized water in turn, and cleaned in an ultrasonic cleaner for 15 minutes each to remove impurities on the surface of the flow channel substrate and the sealing substrate and keep them clean; Place the flow channel substrate into an oxygen plasma cleaning machine and bombard it at a power of 120 W for 2 minutes; After the flow channel substrate is bombarded, wait for the pressure in the chamber to rise to atmospheric pressure. Without removing the flow channel substrate, place the sealed substrate into the chamber of the oxygen plasma cleaning machine and bombard it together with the flow channel substrate at a power of 120W for 32 seconds. Then take it out. After removing the flow channel substrate and the sealing substrate, add a few drops of anhydrous ethanol as a lubricant to the surfaces to be bonded. This allows the sealing substrate to slide on the flow channel substrate until it is properly aligned. Use a rolling brush to press and align the bonded chips until all bubbles between the flow channel substrate and the sealing substrate are squeezed out. The bonded flow channel substrate and the sealing substrate are subjected to enhanced bonding treatment.

19. The method for preparing a microfluidic chip according to claim 18, wherein: The enhanced bonding treatment of the bonded flow channel substrate and the sealing substrate comprises: The partially bonded flow channel substrate and sealing substrate are placed in a vacuum drying oven for evacuation to remove the anhydrous ethanol.

20. The method for preparing a microfluidic chip according to claim 18, wherein: The enhanced bonding treatment of the bonded flow channel substrate and the sealing substrate comprises: The bonded flow channel substrate and sealing substrate were placed on a heating platform at 95° C. and heated for 24 h.

21. The method for preparing a microfluidic chip according to claim 15, wherein: Also includes: Before the chip positive mold preparation step is performed based on the single crystal silicon wafer, the single crystal silicon wafer is cleaned and subjected to surface hydrophilic treatment.

22. The method for preparing a microfluidic chip according to claim 21, wherein: The cleaning and surface hydrophilic treatment of the single crystal silicon wafer comprises: placing the single crystal silicon wafer in a piranha solution and heating it; The heated single crystal silicon wafer was ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 15 minutes respectively, taken out and blown dry with a nitrogen gun, and placed on a hot plate at 120° and heated for 30 minutes to completely dry the single crystal silicon wafer; The cleaned single crystal silicon wafer is placed with the surface facing upward in a plasma cleaning machine to complete the cleaning process.

23. The method for preparing a microfluidic chip according to claim 15, wherein: Also includes: Before the flow channel of the flow channel substrate is packaged, the prepared flow channel substrate is left to stand, rinsed and dried to prepare the flow channel substrate.

24. The method for preparing a microfluidic chip according to claim 15, wherein: The chip positive mold preparation based on the single crystal silicon wafer includes: Injecting photoresist at the center of the single crystal silicon wafer and placing the silicon wafer with the photoresist on the chuck of the spin coater, and using the spin coater to spin coat the photoresist; Placing the silicon wafer on a heating table for pre-baking, and placing a mask with the pre-designed liquid electrode-based microfluidic system on a photolithography machine film frame; Use a photolithography machine to perform photolithography on silicon wafers; After photolithography, the silicon wafer is post-baked and developed, and finally dried with nitrogen, and then placed on a heating table again for hardening and baking to obtain the positive mold of the liquid electrode-based microfluidic system.

25. The method for preparing a microfluidic chip according to claim 24, wherein: The thickness of the male mold of the liquid electrode-based microfluidic channel system is 50 microns.

26. The method for preparing a microfluidic chip according to claim 15, wherein: The static hydrophobic treatment of the male mold of the liquid electrode-based microfluidic system includes: The obtained positive mold of the microfluidic channel system was placed in a volatile cylinder, and three drops of perfluorodecyltriethylsilane were dripped into the volatile cylinder. After sealing, the volatile cylinder was placed in an oven for heating and baking.

27. The method for preparing a microfluidic chip according to claim 15, wherein: The process of pouring the prepared flow channel substrate material into the positive mold of the liquid electrode-based microfluidic system to prepare the flow channel substrate microfluidic system comprises: The PDMS prepolymer and curing agent were evenly mixed in a weight ratio of 10:1, stirred evenly, and then placed in a vacuum drying oven for degassing for 30 minutes; A certain amount of PDMS was drawn up by a syringe and poured onto the positive template of the microfluidic system, and then placed in a vacuum drying oven for degassing for 30 minutes, and then placed on a heating table for heating and curing to prepare a microfluidic system of the flow channel substrate.

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