Microfluidic chip based on dual-electrode group, charging system and preparation method thereof

Abstract

The present invention provides a microfluidic chip based on a dual-electrode group, a charging system, and a preparation method thereof. The microfluidic chip includes: 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, and a first charging electrode and a second charging electrode; the first charging electrode and the second charging electrode have the same electrode shape as the first electrode channel and the second electrode channel when the channel substrate and the sealing substrate are bonded; the first charging electrode and the second charging electrode are suitable for providing a charging voltage to the first conductive solution and the second conductive solution in the first electrode channel and the second electrode channel, so as to cause electrostatic induction of the dispersed phase conductive solution in the droplet generation channel and the droplet transport channel; the dispersed phase conductive solution generates charged droplets through the electrostatic induction. The present invention can improve the charging structure of microfluidic technology and increase the efficiency of droplet generation and droplet charging.

Description

Technical Field

[0001] The present invention relates to the field of microfluidic technology, and in particular to a microfluidic chip based on a dual-electrode group, a dual-electrode group charging system based on the 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 improve the efficiency of droplet generation and droplet charging.

[0012] In order to solve the above technical problems, the technical solution of the present invention provides a microfluidic chip based on a dual-electrode group, comprising: a flow channel substrate and a sealing substrate, wherein the flow channel substrate is provided with: a dispersed phase transport flow channel, a first continuous phase flow channel and a second continuous phase flow channel, a droplet generation flow channel, a droplet transport flow channel, a first electrode flow channel and a second electrode flow channel;

[0013] The dispersed phase delivery channel is suitable for delivering a dispersed phase conductive solution, the first continuous phase flow channel and the second continuous phase flow channel are suitable for delivering a first continuous phase fluid and a second continuous phase fluid, respectively. The dispersed phase delivery channel, the first continuous phase flow channel and the second continuous phase flow channel are cross-connected to form a cross intersection, so that the dispersed phase conductive solution intersects with the first continuous phase flow channel and the second continuous phase flow channel at the cross intersection to enter the droplet generation channel; the dispersed phase conductive solution is subjected to shear forces of the first continuous phase fluid and the second continuous phase fluid in the droplet generation channel to generate encapsulated 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 a droplet collection port;

[0014] The first electrode flow channel and the second electrode flow channel are adapted to be symmetrically arranged on both sides of the droplet delivery flow channel to respectively introduce the first conductive solution and the second conductive solution;

[0015] The sealing substrate is provided with: a first charging electrode and a second charging electrode; the first charging electrode and the second charging electrode have the same electrode shape as the first electrode flow channel and the second electrode flow channel when the flow channel substrate and the sealing substrate are bonded;

[0016] The first charging electrode and the second charging electrode are suitable for providing a charging voltage to the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution in the droplet generation flow channel and the droplet transport flow channel; the dispersed phase conductive solution generates charged droplets through the electrostatic induction.

[0017] Optionally, the first charging electrode and the second charging electrode are also suitable for directly providing the charging voltage to the dispersed phase conductive solution in the droplet generation channel and the droplet transport channel when the first conductive solution and the second conductive solution are lacking in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution.

[0018] Optionally, the flow channel substrate is further provided with: a dispersed phase inlet, a first continuous phase inlet, a second continuous phase inlet, a first conductive solution inlet, a first exhaust port, a second conductive solution inlet, a second exhaust port and the droplet collection port; one end of the dispersed phase delivery channel is connected to the dispersed phase inlet to access the dispersed phase conductive solution, and the other end is connected to the cross; one end of the first continuous phase flow channel and the second continuous phase flow channel are respectively connected to the first continuous phase inlet and the second continuous phase inlet to respectively access the first continuous phase fluid and the second continuous phase fluid, and the other ends are both connected to the cross; one end of the first electrode flow channel and the second electrode flow channel are respectively connected to the first conductive solution inlet and the second conductive solution inlet, and the other end are respectively connected to the first exhaust port and the second exhaust port;

[0019] The flow channel substrate is also provided with: a dispersed phase inlet joint, a first continuous phase inlet joint, a second continuous phase inlet joint and a droplet collection outlet joint; the dispersed phase inlet joint, the first continuous phase inlet joint, the second continuous phase inlet joint and the droplet collection outlet joint are correspondingly coaxially matched with the dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet and the droplet collection port and are connected through.

[0020] Optionally, the sealing substrate is further provided with: a first electrode interface and a second electrode interface; the first charging electrode and the second charging electrode are respectively provided with the first electrode interface and the second electrode interface at both ends.

[0021] Optionally, the first electrode flow channel and the second electrode flow channel are U-shaped flow channels symmetrically arranged with the droplet delivery flow channel as the center line; the bottoms of the first electrode flow channel and the second electrode flow channel are arranged close to the droplet delivery flow channel, and the U-shaped openings are arranged away from the droplet delivery flow channel;

[0022] The first charging electrode and the second charging electrode are electrodes of the same U-shape. When the flow channel substrate and the sealing substrate are bonded, the first charging electrode and the second charging electrode are symmetrically arranged with the droplet delivery channel as the center line, and the bottoms of the first charging electrode and the second charging electrode are arranged close to the droplet delivery channel, and the U-shaped openings are arranged away from the droplet delivery channel.

[0023] Optionally, the first charging electrode and the second charging electrode are prepared by a Lift-Off process.

[0024] Optionally, the first charging electrode, the second charging electrode, the first electrode interface and the second electrode interface are formed by stacking silicon oxide-aluminum from the bottom layer upwards.

[0025] Optionally, the cross intersection is suitable for connecting to the first continuous phase flow channel upward, connecting to the second continuous phase flow channel downward, connecting to the dispersed phase transport flow channel to the left, and connecting to the droplet generation flow channel and the droplet transport flow channel to the right in sequence.

[0026] In order to solve the above technical problems, the technical solution of the present invention further provides a dual-electrode group charging system suitable for a microfluidic chip, wherein the microfluidic chip is formed by bonding a flow channel substrate and a sealing substrate, and comprises: a first electrode flow channel and a second electrode flow channel provided on the flow channel substrate, and a first charging electrode and a second charging electrode provided on the sealing substrate; the first charging electrode and the second charging electrode have the same electrode shape as the first electrode flow channel and the second electrode flow channel when the flow channel substrate and the sealing substrate are bonded;

[0027] The flow channel substrate is further provided with a droplet generation flow channel and a droplet transport flow channel, and the first electrode flow channel and the second electrode flow channel are symmetrically arranged on both sides of the droplet transport flow channel to respectively pass the first conductive solution and the second conductive solution;

[0028] The first charging electrode and the second charging electrode are suitable for providing a charging voltage to the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution in the droplet generation flow channel and the droplet transport flow channel; the dispersed phase conductive solution generates charged droplets through the electrostatic induction.

[0029] Optionally, the first charging electrode and the second charging electrode are also suitable for directly providing the charging voltage to the dispersed phase conductive solution in the droplet generation channel and the droplet transport channel when the first conductive solution and the second conductive solution are lacking in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution.

[0030] Optionally, the sealing substrate is further provided with: a first electrode interface and a second electrode interface; the first charging electrode and the second charging electrode are respectively provided with the first electrode interface and the second electrode interface at both ends.

[0031] Optionally, the first electrode flow channel and the second electrode flow channel are U-shaped flow channels symmetrically arranged with the droplet delivery flow channel as the center line; the bottoms of the first electrode flow channel and the second electrode flow channel are arranged close to the droplet delivery flow channel, and the U-shaped openings are arranged away from the droplet delivery flow channel;

[0032] The first charging electrode and the second charging electrode are electrodes of the same U-shape. When the flow channel substrate and the sealing substrate are bonded, the first charging electrode and the second charging electrode are symmetrically arranged with the droplet delivery channel as the center line, and the bottoms of the first charging electrode and the second charging electrode are arranged close to the droplet delivery channel, and the U-shaped openings are arranged away from the droplet delivery channel.

[0033] Optionally, the first charging electrode and the second charging electrode are prepared by a Lift-Off process.

[0034] Optionally, the first charging electrode, the second charging electrode, the first electrode interface and the second electrode interface are formed by stacking silicon oxide-aluminum from the bottom layer upwards.

[0035] 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:

[0036] A chip positive mold is prepared based on a single crystal silicon wafer to obtain a positive mold of a microfluidic system; the microfluidic system includes: 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;

[0037] Performing a hydrophobic treatment on the positive mold of the microfluidic channel system;

[0038] pouring the prepared flow channel substrate material into the microfluidic system male mold to prepare the microfluidic system of the flow channel substrate;

[0039] 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;

[0040] preparing a charging electrode pattern on a packaging substrate material;

[0041] Based on the charging electrode pattern, thin-film metal electrodes of a first charging electrode and a second charging electrode are prepared on the packaging substrate material to form a packaging substrate; the first charging electrode and the second charging electrode have the same electrode shape as the first electrode flow channel and the second electrode flow channel;

[0042] The flow channel is packaged based on the prepared flow channel substrate and packaging substrate to obtain a microfluidic chip.

[0043] Optionally, the chip positive mold preparation based on a single crystal silicon wafer includes:

[0044] cleaning the single crystal silicon wafer;

[0045] Performing surface hydrophilic treatment on the cleaned single crystal silicon wafer;

[0046] 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;

[0047] The silicon wafer is placed on a heating table for pre-baking, and a mask with a pre-designed flow channel system is placed on a film-curing rack of a photolithography machine;

[0048] Performing photolithography on the silicon wafer using a photolithography machine;

[0049] 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 a chip positive mold.

[0050] Optionally, the cleaning of the single crystal silicon wafer 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] Optionally, performing surface hydrophilic treatment on the cleaned single crystal silicon wafer includes: placing the cleaned single crystal silicon wafer with its surface facing upward in a plasma cleaning machine to complete the cleaning treatment.

[0054] Optionally, the hydrophobic treatment of the positive mold of the microfluidic channel system includes:

[0055] 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.

[0056] 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:

[0057] 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 microfluidic system was prepared.

[0058] Optionally, the step of preparing a charging electrode pattern on a packaging substrate material includes:

[0059] Cleaning the packaging substrate material;

[0060] Performing surface hydrophilic treatment on the cleaned packaging substrate material;

[0061] injecting photoresist at the center of the packaging substrate material;

[0062] Place the packaging substrate material with photoresist on the chuck of the coating machine, use the coating machine to spin-coat the photoresist and complete the pre-baking of the packaging substrate material;

[0063] Placing the pre-baked packaging substrate material under a pre-baked film designed with a desired charging electrode pattern, and photolithography the packaging substrate material using a photolithography machine;

[0064] Post-baking the package substrate material after photolithography;

[0065] After the post-baking is completed, the packaging substrate material is developed at room temperature until no white precipitate appears;

[0066] The packaging substrate material is cleaned and dried.

[0067] Optionally, the cleaning of the packaging substrate material includes: ultrasonically cleaning the packaging substrate material with acetone, anhydrous ethanol and deionized water for 15 minutes respectively, taking it out and blowing it dry with a nitrogen gun, placing it on a hot plate at room temperature, slowly heating it to 120°C and heating it for 30 minutes, and drying it to obtain a dry packaging substrate material.

[0068] Optionally, performing surface hydrophilic treatment on the cleaned packaging substrate material includes placing the packaging substrate material in a plasma cleaning machine for surface activation.

[0069] Optionally, the thin-film metal electrodes of the first charging electrode and the second charging electrode are prepared on the packaging substrate material based on the charging electrode pattern to form a packaging substrate, including: placing the obtained packaging substrate material with the pattern in a magnetron sputtering machine, first sputtering a first layer of silicon oxide film, then sputtering an aluminum film, and finally taking out the coated packaging substrate material to obtain the product.

[0070] Optionally, the thickness of the first silicon oxide film is 150 nm, and the thickness of the aluminum film is 100 nm.

[0071] Optionally, the method for preparing the microfluidic chip further includes: allowing the packaging substrate material having the first charging electrode and the second charging electrode to stand, rinse, and dry to prepare the packaging substrate.

[0072] The beneficial effects of the technical solution of the present invention include at least:

[0073] The microfluidic chip provided by the technical solution of the present invention adopts a dual charging system of liquid electrodes and charging electrodes, which has a simple structure. The dual electrode group structure of liquid electrodes and charging electrodes can realize the simultaneous generation of droplets and charging of droplets. While simplifying the preparation process of droplet charging microfluidic chips, it provides an efficient operation method for droplet microfluidics, greatly improving the efficiency of manufacturing and use.

[0074] 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.

[0075] The technical solution of the present invention can make the droplets generated by the droplet microfluidic chip positively charged, negatively charged or uncharged as required; it further realizes charging the droplets on demand while the droplets are generated, making related droplet products more practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0076] 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:

[0077] Figure 1 A schematic structural diagram of a microfluidic chip provided by the technical solution of the present invention;

[0078] Figure 2 Schematic diagram of the charging electrode structure of the microfluidic chip provided by the technical solution of the present invention;

[0079] Figure 3 A schematic diagram of the microfluidic system structure of the microfluidic chip provided by the technical solution of the present invention;

[0080] Figure 4 A schematic diagram of the working state of the microfluidic system based on dual-electrode group charging provided by the technical solution of the present invention;

[0081] Figure 5 A schematic diagram of the dimensional structure of the width and depth of the rectangular flow channel and the electrode flow channel provided by the technical solution of the present invention;

[0082] Figure 6 A schematic diagram of the connector structure of the microfluidic system provided by the technical solution of the present invention;

[0083] Figure 7 The present invention provides a schematic diagram of the structure of a dual-electrode group charging system for a microfluidic chip;

[0084] Figure 8 The technical solution of the present invention provides a schematic flow chart of the steps of a method for preparing a microfluidic chip. DETAILED DESCRIPTION

[0085] 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.

[0086] Example 1

[0087] This embodiment provides a microfluidic chip based on a dual-electrode group, which can simultaneously realize droplet generation and droplet charging. Figure 1 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.

[0088] A microfluidic system is configured on the channel substrate, which includes: a dispersed phase transport channel 104, a continuous phase channel 105, a continuous phase channel 106, a droplet generation channel 107, a droplet transport channel 108, an electrode channel 109 and an electrode channel 110.

[0089] The dispersed phase delivery channel 104 is connected to the dispersed phase inlet 101 , and the dispersed phase conductive solution can be introduced into the dispersed phase delivery channel 104 from the dispersed phase inlet 101 . The dispersed phase delivery channel 104 is suitable for delivering the dispersed phase conductive solution.

[0090] The continuous phase flow channel 105 and the continuous phase flow channel 106 are connected to the continuous phase inlet 102 and the continuous phase inlet 103 respectively. The continuous phase fluid can enter the continuous phase flow channel 105 and the continuous phase flow channel 106 through the continuous phase inlet 102 and the continuous phase inlet 103, so that the continuous phase flow channel 105 and the continuous phase flow channel 106 are filled with the continuous phase fluid.

[0091] Continue to refer Figure 1 The dispersed phase delivery channel 104 is cross-connected with the continuous phase flow channel 105 and the continuous phase flow channel 106 to form a cross intersection, so that the dispersed phase conductive solution in the dispersed phase delivery channel 104 intersects with the continuous phase fluid in the continuous phase flow channel 105 and the continuous phase flow channel 106 at the cross intersection. More specifically, the cross intersection can be Figure 1 The directions shown are relatively connected upward to the continuous phase flow channel 105, downward to the continuous phase flow channel 106, leftward to the dispersed phase delivery flow channel 104, and rightward to the droplet generation flow channel 107. The dispersed phase conductive solution in the dispersed phase delivery flow channel 104 and the continuous phase fluids in the continuous phase flow channels 105 and 106 meet at the intersection and then simultaneously enter the droplet generation flow channel 107. In the droplet generation flow channel 107, the dispersed phase conductive solution is subjected to the shear force of the continuous phase fluid and its own surface tension, causing it to break and produce individually encapsulated droplets.

[0092] Continue to refer Figure 1The droplet generation channel 107 is connected to the droplet delivery channel 108, and the droplet delivery channel 108 is connected to the droplet collection port 111. The electrode channel 109 and the electrode channel 110 are symmetrically arranged on both sides of the droplet delivery channel 108, and are respectively fed with the first conductive solution and the second conductive solution.

[0093] Set corresponding to the electrode flow channel 109 and the electrode flow channel 110, Figure 1 The sealing substrate is provided with charging electrodes 201 and 202. Charging electrodes 201 and 202 have the same electrode shape as electrode channels 109 and 110, and may also have the same planar structure. When the channel substrate and the sealing substrate are bonded, the electrode group consisting of charging electrodes 201 and 202 is positioned opposite the electrode group consisting of electrode channels 109 and 110 (referring to the identical planar projection structure and position between the electrode groups), forming the dual-electrode group of the microfluidic chip of the present invention.

[0094] More specifically, when the technical solution of the present invention Figure 1 When the illustrated microfluidic chip is in use, the charging electrodes 201 and 202 can provide a charging voltage to the electrode flow channels 109 and 110. If the first and second conductive solutions are introduced into the electrode flow channels 109 and 110, the conductive solutions in the electrode flow channels 109 and 110 become charged under the charging voltage provided by the charging electrodes 201 and 202, and electrostatic induction is generated between the dispersed-phase conductive solutions in the droplet generation channel 107 and the droplet transport channel 108. If the first and second conductive solutions are not present in the electrode flow channels 109 and 110, that is, if the electrode flow channels 109 and 110 lack the corresponding conductive solutions, the charging electrodes 201 and 202 can directly provide a charging voltage to the dispersed-phase conductive solutions in the droplet generation channel 107 and the droplet transport channel 108, causing electrostatic induction between the dispersed-phase conductive solutions in the droplet generation channel 107 and the droplet transport channel 108. The dispersed conductive solution in the droplet generation channel 107 and the droplet delivery channel 108 can generate charged droplets through electrostatic induction.

[0095] Combine Figure 2 The charging electrodes 201 and 202 on the sealed substrate further have electrode interfaces for connecting to electricity, enabling the charging electrodes 201 and 202 to generate a charging voltage. Specifically, the charging electrode 201 has electrode interfaces 203a and 203b at both ends, respectively, while the charging electrode 202 has electrode interfaces 204a and 204b at both ends.

[0096] The charging electrodes 201 and 202 can be fabricated using a lift-off process. The charging electrodes 201 and 202, as well as their respective electrode interfaces 203a and 203b, and electrode interfaces 204a and 204b, can be formed by stacking silicon oxide-aluminum from the bottom up on a sealing substrate.

[0097] Combine Figure 3 The flow channel substrate may further be provided with: a dispersed phase inlet 101, a continuous phase inlet 102, a continuous phase inlet 103, a conductive solution inlet 1091, an exhaust port 1092, a conductive solution inlet 1111, an exhaust port 1112, and a droplet collection port 111. The dispersed phase inlet 101, the continuous phase inlet 102, and the continuous phase inlet 103 are sequentially arranged in the dispersed phase delivery channel 104, the continuous phase channel 105, and the continuous phase channel 106. The corresponding dispersed phase conductive solution and continuous phase fluid are introduced through the dispersed phase inlet 101, the continuous phase inlet 102, the continuous phase inlet 103, the dispersed phase delivery channel 104, the continuous phase channel 105, and the continuous phase channel 106. At the intersection, the introduced dispersed phase conductive solution and continuous phase fluid enter the droplet generation channel 107, and encapsulated droplets are generated in the droplet generation channel 107. These droplets enter the droplet delivery channel 108 through the droplet generation channel 107 and generate charged droplets through electrostatic induction.

[0098] Continue to refer Figure 3 Electrode flow channels 109 and 110 are U-shaped channels symmetrically arranged with the droplet transport channel 108 as the centerline. The bottoms of the U-shaped channels of electrode flow channels 109 and 110 are located close to the droplet transport channel 108, while the U-shaped openings are located away from the droplet transport channel. A conductive solution inlet 1091 and an exhaust port 1092 are located at both ends of the U-shaped channel of electrode flow channel 109, while a conductive solution inlet 1111 and an exhaust port 1112 are located at both ends of the U-shaped channel of electrode flow channel 110.

[0099] Combine Figure 2 As can be seen, charging electrodes 201 and 202 are also U-shaped electrodes, just like electrode channels 109 and 110. Electrode interfaces 203a and 203b are located at either end of the U-shaped opening of charging electrode 201, while electrode interfaces 204a and 204b are located at either end of the U-shaped opening of charging electrode 202. When the channel substrate and the sealing substrate are bonded, charging electrodes 201 and 202 are also symmetrically arranged around the droplet transport channel 108. The bottoms of the U-shaped electrodes of charging electrodes 201 and 202 are positioned close to the droplet transport channel 108, while the U-shaped opening and the electrode interfaces at both ends are positioned away from the droplet transport channel 108.

[0100] When the conductive solution enters the electrode flow channels 109 and 110 through the conductive solution inlet 1091 and the conductive solution inlet 1111, the electrode flow channels 109 and 110 are filled with the conductive solution. At this point, the charging electrodes 201 and 202 are connected to the electrode interface 203a and the electrode interface 203b, and the electrode interface 204a and the electrode interface 204. The charging electrodes 201 and 202 provide a charging voltage to the electrode flow channels 109 and 110, turning the electrode flow channels 109 and 110 into liquid electrodes, thereby providing electrostatic induction for the droplets entering the droplet delivery channel 108 through the droplet generation channel 107.

[0101] The conductive solution in the electrode flow channel 109 and the electrode flow channel 110 can also be emptied through the exhaust port 1092 and the exhaust port 1112. If there is no conductive solution in the electrode flow channel 109 and the electrode flow channel 110, the charging electrode 201 and the charging electrode 202 are connected to the power through the electrode interface. The charging electrode 201 and the charging electrode 202 can be directly used as charging electrodes to perform electrostatic induction on the droplets that pass through the droplet generation channel 107 and enter the droplet transport channel 108, so that the droplets are charged.

[0102] Combine Figure 4 In the microfluidic system of this embodiment, the dispersed phase delivery channel 104 is cross-connected with the continuous phase channel 105 and the continuous phase channel 106 to form a cross intersection. Figure 4 When the dispersed phase conductive solution is introduced into the dispersed phase delivery channel 104, the dispersed phase conductive solution is adapted to intersect with the continuous phase fluid in the continuous phase flow channel 105 and the continuous phase flow channel 106 at the cross intersection to enter the droplet generation channel. Figure 4 Figure 1 illustrates the flow direction a of the dispersed-phase conductive solution and the flow directions b and c of the continuous-phase fluid. The dispersed-phase conductive solution in the droplet generation channel 107 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.

[0103] Continue to refer Figure 4 The droplet delivery channel 108 is connected to the droplet collection port. The droplet collection port can be set on the microfluidic chip (see Figure 3 The droplet collection port 111 is provided at the end of the droplet delivery channel 108. The droplet delivery channel 108 may be configured as follows Figure 3 The droplet collection port 111 is connected to the microfluidic chip. In other embodiments, the droplet delivery channel 108 port can also be radially divided into multiple separation channels, and the multiple separation channels are suitable for being connected to the droplet collection ports of multiple microfluidic chips respectively.

[0104] The microfluidic system of the technical solution of the present invention adopts a dual electrode group structure, namely, a liquid electrode group consisting of electrode flow channel 109 and electrode flow channel 110, and a charging electrode group consisting of charging electrode 201 and charging electrode 202. The technical solution of the present invention provides a charging voltage to the liquid electrode through the charging electrode group, and the positive or negative pressure of the charging voltage makes the liquid electrode group positively or negatively charged.

[0105] 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 4 Medium positively charged droplet (4);

[0106] When the liquid 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 generated droplets will be negatively charged, forming Figure 4 The negatively charged droplet (3).

[0107] When the microfluidic chip is powered on and working, the microfluidic chip using the technical solution of the present invention works simultaneously with the droplet generation in the cross structure under the charging voltage. Therefore, the microfluidic chip using the technical solution of the present invention can achieve the technical effect of simultaneous droplet generation and droplet charging.

[0108] In the above-mentioned microfluidic chip of the technical solution of the present invention, if there is no conductive solution in the liquid electrode, since the charging electrode and the liquid electrode have the same planar shape, the charging electrode can directly provide a charging voltage (positive or negative pressure) to perform electrostatic induction with the droplets in the dispersed conductive solution:

[0109] When the charging electrode is negatively charged, the charging 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 4 Medium positively charged droplet (4);

[0110] When the charging electrode is connected to a positive charge, the charging 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 generated droplets will be negatively charged, forming Figure 4 The negatively charged droplet (3).

[0111] Therefore, when the microfluidic chip is powered on, the charging electrode can directly provide a charging voltage when the liquid electrode does not contain a charging solution, and work simultaneously with the droplet generation in the cross-cross structure. Under the dual-electrode group microfluidic chip of the technical solution of the present invention, the technical effect of simultaneous droplet generation and droplet charging in two working modes is provided.

[0112] Continue to refer Figure 4, and combined with Figure 5 ( Figure 5 (This is a cross-sectional view of the flow channel of the microfluidic system perpendicular to the direction of liquid flow, in which the depth and width of the flow channel can be seen). In this embodiment, the microfluidic system suitable for the microfluidic chip can also be configured according to the following sizes and shapes:

[0113] The bottom of the U-shaped channel of the electrode channel 109 is set close to the droplet transport channel 108 and the configuration distance S1 is 500 microns. The U-shaped opening end of the U-shaped channel is set away from the droplet transport channel 108, and the configuration distance S2 between the left channel of the U-shaped channel and the continuous phase channel 105 is 2 mm.

[0114] Similarly, the bottom of the U-shaped channel of the electrode channel 110 is set close to the droplet delivery channel 108 and the configuration distance S3 is 500 microns. The U-shaped opening end of the U-shaped channel is set away from the droplet delivery channel 108, and the setting distance S4 between the left channel of the U-shaped channel and the continuous phase channel 106 is 2 mm.

[0115] More specifically, the dispersed phase delivery channel 104 is a rectangular channel, which may be 50 microns wide and 50 microns deep. The continuous phase channel 105 and the continuous phase channel 106 are rectangular channels, which may be 60 microns wide and 50 microns deep. The droplet generation channel 107 is a rectangular channel, which may be 50 microns wide, 50 microns deep and 50 microns long ( Figure 4 The length k2 of the droplet generation channel 107 is also shown. The droplet transport channel 108 is a rectangular channel with a width of 100 microns and a depth of 50 microns. Electrode channels 109 and 110 are rectangular channels. Since electrode channels 109 and 110 are U-shaped channels, their bottom channels are both 400 microns wide and 50 microns deep, while the side channels are 100 microns wide and 50 microns deep.

[0116] This embodiment does not limit the lengths of the dispersed phase delivery channel 104 , the continuous phase channel 105 , the continuous phase channel 106 , and the droplet delivery channel 108 .

[0117] It should be noted that:

[0118] 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.

[0119] In the dimensions of the above microfluidic system, the width and depth of the rectangular channel refer to Figure 5 The figure shows the width and depth of the cross section perpendicular to the flow direction of the channel fluid, where the two electrode channels are shown. Figure 4The channel depth and width of the middle electrode channel 109 and the electrode channel 110, and the rectangular channel indicate the channel depth and width of the droplet transport channel 108. Figure 4 , Figure 4 The rectangular channel width k1 of the dispersed phase delivery channel 104 is also shown. The depth of the rectangular channel can be referred to Figure 5 , is the etching depth of the corresponding channel on the channel substrate. Similarly, the depth of the electrode channel can be referred to Figure 5 , is the etching depth of the corresponding electrode channel on the channel substrate.

[0120] 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 be glass or PMMA.

[0121] Combine Figure 6 In the microfluidic chip of the technical solution of the present invention, the flow channel substrate may also be provided with: a dispersed phase inlet connector 301, a continuous phase inlet connector 303, a continuous phase inlet connector 302 and a droplet collection outlet connector 304. The dispersed phase inlet connector 301, the continuous phase inlet connector 303, the continuous phase inlet connector 302 and the droplet collection outlet connector 304 can be coaxially matched with the dispersed phase inlet 101, the continuous phase inlet 102, the continuous phase inlet 103 and the droplet collection outlet 111 and connected therethrough. The dispersed phase inlet connector 301 is a conductive connector, and its material 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 the dispersed phase inlet connector 301 is connected to an external electrode and the electrode is energized, the conductive fluid in the dispersed phase will become conductive and sense the fluid in the electrode flow channels 109 and 110.

[0122] Example 2

[0123] Based on Figures 1 to 6 The present embodiment provides a dual-electrode charging system applicable to the microfluidic chip. Figure 7 As shown, including:

[0124] Electrode flow channels 109 and 110 provided on the flow channel substrate; and

[0125] The charging electrodes 201 and 202 are provided on the sealing substrate.

[0126] Figure 7It can be seen that the charging electrode 201 and the charging electrode 202 (constituting the charging electrode group) have the same electrode shape as the electrode flow channel 109 and the electrode flow channel 110 (constituting the liquid electrode group). When the flow channel substrate and the sealing substrate are bonded, the projections of the charging electrode group and the liquid electrode group on the substrate plane are consistent. According to the description of Example 1, the electrode flow channel 109 and the electrode flow channel 110 are symmetrically arranged on both sides of the droplet transport flow channel, and a conductive solution can be passed through. The charging electrode 201 and the charging electrode 202 can provide a charging voltage to the electrode flow channel 109 and the electrode flow channel 110, so that the electrode flow channel 109 and the electrode flow channel 110 form liquid electrodes under the charging voltage, and electrostatically induce the dispersed phase conductive solution in the droplet generation flow channel and the droplet transport flow channel. The dispersed phase conductive solution generates charged droplets through this electrostatic induction. If there is no conductive solution in electrode flow channels 109 and 110, charging electrodes 201 and 202, sharing the same planar shape as the liquid electrode assembly, can directly electrostatically induce the dispersed conductive solution in the droplet generation and transport channels. This embodiment's charging system, based on a dual-electrode assembly, can implement two liquid charging methods.

[0127] Continue to refer Figure 7 Combined with Figures 1 to 6 The dual-electrode charging system further comprises electrode interfaces 203a, 203b, 204a, and 204b disposed on the sealed substrate. Electrode interfaces 203a and 203b are located at the two open ends of the U-shaped electrode of charging electrode 201, and electrode interfaces 204a and 204b are located at the two open ends of the U-shaped electrode of charging electrode 202.

[0128] The specific technical means such as the arrangement, shape, preparation scheme and structure of the charging electrode group and the liquid electrode group of the dual-electrode group charging system can be referred to Example 1 and will not be repeated here.

[0129] Example 3

[0130] Based on the above Figures 1 to 6 The present embodiment provides a method for preparing a microfluidic chip. Figure 8 , including the following steps:

[0131] Step S100 , preparing a chip positive mold based on a single crystal silicon wafer to obtain a microfluidic system positive mold.

[0132] The specific structure of the microfluidic system can refer to the first embodiment, and may include: dispersed phase transport channel 104, continuous phase channel 105 and continuous phase channel 106, droplet generation channel 107, droplet transport channel 108, electrode channel 109 and electrode channel 110.

[0133] Based on the above-mentioned microfluidic system, the microfluidic system may further include: a dispersed phase inlet 101, a continuous phase inlet 102, a continuous phase inlet 103, a conductive solution inlet 1091, an exhaust port 1092, a conductive solution inlet 1111, an exhaust port 1112, and a droplet collection port 111. The dispersed phase inlet 101, the continuous phase inlet 102, and the continuous phase inlet 103 are sequentially located at the flow channel ports of the dispersed phase delivery channel 104, the continuous phase flow channel 105, and the continuous phase flow channel 106, respectively, to introduce the corresponding dispersed phase conductive solution and continuous phase fluid into the dispersed phase delivery channel 104, the continuous phase flow channel 105, and the continuous phase flow channel 106. The conductive solution inlet 1091 and the exhaust port 1092 are located at both ends of the U-shaped flow channel of the electrode flow channel 109, and the conductive solution inlet 1111 and the exhaust port 1112 are located at both ends of the U-shaped flow channel of the electrode flow channel 110. One end of the droplet delivery channel 108 is connected to the cross intersection, and the other end is connected to the droplet collection port 111 .

[0134] Based on the above-mentioned microfluidic system, the microfluidic system may further include: a dispersed phase inlet connector 301, a continuous phase inlet connector 303, a continuous phase inlet connector 302, and a droplet collection outlet connector 304. The dispersed phase inlet connector 301, the continuous phase inlet connector 303, the continuous phase inlet connector 302, and the droplet collection outlet connector 304 may be coaxially matched with and connected to the dispersed phase inlet 101, the continuous phase inlet 102, the continuous phase inlet 103, and the droplet collection outlet 111, respectively. The dispersed phase inlet connector 301, the continuous phase inlet connector 303, the continuous phase inlet connector 302, and the droplet collection outlet connector 304 may be connected to external electrodes, so that when the external electrodes are energized, the fluid in the corresponding flow channel becomes conductive.

[0135] More specifically, a chip positive mold can be prepared based on a single-crystal silicon wafer in the following manner: the single-crystal silicon wafer is cleaned; the surface of the cleaned single-crystal silicon wafer is hydrophilized; photoresist is injected into the center of the single-crystal silicon wafer and the silicon wafer with the photoresist is placed on the suction cup of a spreader, and the photoresist is spin-coated using a spreader; the silicon wafer is placed on a heating table for pre-baking, and a mask with a pre-designed flow channel system is placed on the film-curing rack of a photolithography machine; the silicon wafer is photolithographyed using a photolithography machine; and, after photolithography, the silicon wafer is post-baked and developed, and finally dried with nitrogen, and placed on a heating table again for hardening and baking to obtain a chip positive mold.

[0136] The specific process of cleaning the single crystal silicon wafer can be: placing the single crystal silicon wafer in piranha solution and heating it; ultrasonically cleaning the heated single crystal silicon wafer with acetone, anhydrous ethanol and deionized water for 15 minutes respectively, taking it out and blowing it dry with a nitrogen gun, and placing it on a hot plate at 120° and heating it for 30 minutes to completely dry the single crystal silicon wafer.

[0137] The specific process of performing surface hydrophilic treatment on the cleaned single crystal silicon wafer may be as follows: the cleaned single crystal silicon wafer is placed with its surface facing upward in a plasma cleaning machine to complete the cleaning process.

[0138] Continue to refer Figure 8 , the preparation method of the microfluidic chip further includes:

[0139] Step S101 , performing hydrophobic treatment on the positive mold of the microfluidic channel system.

[0140] In step S101, the specific process of performing hydrophobic treatment on the positive mold of the microfluidic system can be: placing the obtained positive mold of the microfluidic system in a volatile cylinder, taking three drops of perfluorodecyltriethylsilane and dripping them into the volatile cylinder, after sealing, placing the volatile cylinder in an oven for heating and baking.

[0141] Step S102 , pouring the prepared material of the flow channel substrate into the positive mold of the microfluidic system to prepare the microfluidic system of the flow channel substrate.

[0142] In step S102, the material of the prepared flow channel substrate is poured into the positive mold of the microfluidic system to prepare the microfluidic system of the flow channel substrate, including the following process: the PDMS prepolymer and the curing agent are evenly mixed in a weight ratio of 10:1, stirred evenly, and placed in a vacuum drying oven for degassing for 30 minutes, and then a certain amount of PDMS is drawn by a syringe and poured onto the positive template of the microfluidic system, and placed in a vacuum drying oven for degassing for 30 minutes, and then placed on a heating table for heating and curing, and finally the microfluidic system is prepared.

[0143] Step S103 , cooling the prepared flow channel substrate and cutting and punching the micro-channel system of the flow channel substrate to prepare the required flow channel substrate.

[0144] Step S104: preparing a charging electrode pattern on the packaging substrate material.

[0145] In step S104, a charging electrode pattern can be prepared on the packaging substrate material in the following manner: cleaning the packaging substrate material; performing a surface hydrophilic treatment on the cleaned packaging substrate material; injecting photoresist into the center of the packaging substrate material; placing the packaging substrate material with the photoresist on top of the chuck of the coating machine, using the coating machine to spin-coat the photoresist and complete pre-baking of the packaging substrate material; placing the pre-baked packaging substrate material under a pre-baked film designed with the required charging electrode pattern, and using a photolithography machine to photolithography the packaging substrate material; post-baking the photolithographic packaging substrate material; after the post-baking is completed, developing the packaging substrate material at room temperature until no white precipitate appears; and cleaning and drying the packaging substrate material.

[0146] The specific process of cleaning the packaging substrate material may include: ultrasonically cleaning the packaging substrate material with acetone, anhydrous ethanol and deionized water for 15 minutes respectively, taking it out and blowing it dry with a nitrogen gun, placing it on a hot plate at room temperature, slowly heating it to 120°C and heating it for 30 minutes, and drying it to obtain a dry packaging substrate material.

[0147] The specific process of performing surface hydrophilic treatment on the cleaned packaging substrate material may include: placing the packaging substrate material in a plasma cleaning machine for surface activation.

[0148] Step S105 , preparing thin-film metal electrodes of first and second charging electrodes on the packaging substrate material based on the charging electrode pattern to form a packaging substrate; the first and second charging electrodes have the same electrode shape as the first and second electrode channels.

[0149] In step S105, a thin-film metal electrode for the charging electrode can be formed on the packaging substrate material based on the charging electrode pattern by placing the resulting patterned packaging substrate material in a magnetron sputtering machine, first sputtering a first layer of silicon oxide thin film, then sputtering an aluminum thin film, and finally removing the coated packaging substrate material. The first silicon oxide thin film can be 150 nm thick, and the aluminum thin film can be 100 nm thick.

[0150] In this step, after the thin film metal electrode of the charging electrode on the packaging substrate material is prepared, the packaging substrate material with the charging electrode group can be left to stand, rinsed and dried to prepare the final packaging substrate.

[0151] Continue to refer Figure 8 The method for preparing the microfluidic chip of this embodiment further includes:

[0152] Step S106: perform flow channel packaging based on the prepared flow channel substrate and packaging substrate to obtain a microfluidic chip. The flow channel packaging process of the flow channel substrate and the packaging substrate can adopt the existing bonding method, which will not be repeated here.

[0153] Application Examples

[0154] Based on the technical solution of the present invention Figure 8 The preparation method of the microfluidic chip shown in the figure, this application example provides an application example of preparing a microfluidic chip. The preparation method of the microfluidic chip in this application example includes the following steps:

[0155] A glass substrate and a single crystal silicon wafer are cleaned and subjected to surface hydrophilic treatment;

[0156] preparing a pattern of charging electrodes on the glass substrate;

[0157] Preparing a thin film metal electrode of the charging electrode on the glass substrate based on the pattern to prepare a glass substrate with an electrode;

[0158] A chip positive mold is prepared based on the single crystal silicon wafer to obtain a microfluidic system positive mold;

[0159] Performing a hydrophobic treatment on the positive mold of the microfluidic channel system;

[0160] pouring the prepared PDMS material into the microfluidic system positive mold to prepare a PDMS microfluidic system;

[0161] Cooling the PDMS microfluidic system and cutting and punching the microfluidic system to prepare a PDMS substrate;

[0162] The glass substrate was bonded to the PDMS substrate.

[0163] The glass substrate can be 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.

[0164] 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.

[0165] The pattern of the charging electrode can be prepared on the glass substrate in the following manner:

[0166] injecting photoresist at the center of the glass substrate;

[0167] Place the glass substrate with photoresist on the chuck of the spin coater, use the spin coater to spin coat the photoresist and complete the pre-baking of the glass substrate;

[0168] The pre-baked glass substrate is placed under a pre-baked film designed with a desired charging electrode pattern, and the glass substrate is photoetched using a photolithography machine;

[0169] Post-baking the glass substrate after photolithography;

[0170] After the post-baking is completed, the glass substrate is developed at room temperature until no white precipitate appears;

[0171] The glass substrate is cleaned and dried.

[0172] The process for preparing the thin-film metal electrode for the charging electrode based on the above-mentioned pattern on a glass substrate may include placing the obtained glass substrate with the pattern in a magnetron sputtering machine, first sputtering a first layer of silicon oxide thin film, then sputtering an aluminum thin film, and finally removing the coated glass substrate. The first layer of silicon oxide thin film has a thickness of 150 nm, and the aluminum thin film has a thickness of 100 nm.

[0173] The preparation method of this application example also includes the following steps:

[0174] The glass substrate provided with the charging electrode is left to stand, rinsed and dried to prepare the glass base.

[0175] The following steps can be used to clean single crystal silicon wafers:

[0176] placing the single crystal silicon wafer in a piranha solution and heating it;

[0177] 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.

[0178] The surface hydrophilic treatment of the single crystal silicon wafer can be carried out as follows: the cleaned single crystal silicon wafer is placed with the surface facing upward in a plasma cleaning machine to complete the cleaning treatment.

[0179] The above-mentioned chip positive mold preparation based on the single crystal silicon wafer includes the following process:

[0180] 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;

[0181] 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;

[0182] Use a photolithography machine to perform photolithography on silicon wafers;

[0183] 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.

[0184] The thickness of the chip positive mold may be 50 μm.

[0185] The hydrophobic treatment of the positive mold of the microfluidic system includes the following steps:

[0186] 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.

[0187] The above-mentioned step of pouring the prepared PDMS material into the positive mold of the microfluidic system to prepare the PDMS microfluidic system includes:

[0188] 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.

[0189] The glass substrate prepared in this application example can be bonded to the PDMS substrate by the following process:

[0190] 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;

[0191] The glass substrate was placed in an oxygen plasma cleaning machine and bombarded at a power of 120 W for 2 min;

[0192] 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.

[0193] 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.

[0194] 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.

[0195] The bonded glass substrate and PDMS substrate may also be placed on a heating platform at 95° C. and heated for 24 hours to remove the anhydrous ethanol and enhance the bonding strength.

[0196] 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 chip based on a dual-electrode group, comprising: The flow channel substrate and the sealing substrate are characterized in that the flow channel substrate is provided with: a dispersed phase transport flow channel, a first continuous phase flow channel and a second continuous phase flow channel, a droplet generation flow channel, a droplet transport flow channel, a first electrode flow channel and a second electrode flow channel; The dispersed phase delivery channel is suitable for delivering a dispersed phase conductive solution, the first continuous phase flow channel and the second continuous phase flow channel are suitable for delivering a first continuous phase fluid and a second continuous phase fluid, respectively. The dispersed phase delivery channel, the first continuous phase flow channel and the second continuous phase flow channel are cross-connected to form a cross intersection, so that the dispersed phase conductive solution intersects with the first continuous phase flow channel and the second continuous phase flow channel at the cross intersection to enter the droplet generation channel; the dispersed phase conductive solution is subjected to shear forces of the first continuous phase fluid and the second continuous phase fluid in the droplet generation channel to generate encapsulated 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 a droplet collection port; The first electrode flow channel and the second electrode flow channel are adapted to be symmetrically arranged on both sides of the droplet delivery flow channel to respectively introduce the first conductive solution and the second conductive solution; The sealing substrate is provided with: a first charging electrode and a second charging electrode; the first charging electrode and the second charging electrode have the same electrode shape as the first electrode flow channel and the second electrode flow channel when the flow channel substrate and the sealing substrate are bonded; The first charging electrode and the second charging electrode are suitable for providing a charging voltage to the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution in the droplet generation flow channel and the droplet transport flow channel; the dispersed phase conductive solution generates charged droplets through the electrostatic induction.

2. The microfluidic chip based on a dual-electrode group according to claim 1, characterized in that: The first charging electrode and the second charging electrode are also suitable for directly providing the charging voltage to the dispersed phase conductive solution in the droplet generation channel and the droplet transport channel when the first conductive solution and the second conductive solution are lacking in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution.

3. The microfluidic chip based on a dual-electrode group according to claim 1 or 2, characterized in that: The flow channel substrate is further provided with: a dispersed phase inlet, a first continuous phase inlet, a second continuous phase inlet, a first conductive solution inlet, a first exhaust port, a second conductive solution inlet, a second exhaust port, and the droplet collection port; one end of the dispersed phase delivery channel is connected to the dispersed phase inlet to receive the dispersed phase conductive solution, and the other end is connected to the cross intersection; One end of the first continuous phase flow channel and the second continuous phase flow channel are respectively connected to the first continuous phase inlet and the second continuous phase inlet to respectively receive the first continuous phase fluid and the second continuous phase fluid, and the other end are both connected to the cross intersection; One end of the first electrode flow channel and the second electrode flow channel are connected to the first conductive solution inlet and the second conductive solution inlet respectively, and the other end is connected to the first exhaust port and the second exhaust port respectively; The flow channel substrate is also provided with: a dispersed phase inlet joint, a first continuous phase inlet joint, a second continuous phase inlet joint and a droplet collection outlet joint; the dispersed phase inlet joint, the first continuous phase inlet joint, the second continuous phase inlet joint and the droplet collection outlet joint are correspondingly coaxially matched with the dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet and the droplet collection port and are connected through.

4. The microfluidic chip based on a dual-electrode group according to claim 1 or 2, characterized in that: The sealing substrate is further provided with: a first electrode interface and a second electrode interface; the first charging electrode and the second charging electrode are respectively provided with the first electrode interface and the second electrode interface at both ends.

5. The microfluidic chip based on a dual-electrode group according to claim 1, characterized in that: The first electrode flow channel and the second electrode flow channel are U-shaped flow channels symmetrically arranged with the droplet delivery flow channel as the center line; the bottoms of the first electrode flow channel and the second electrode flow channel are arranged close to the droplet delivery flow channel, and the U-shaped openings are arranged away from the droplet delivery flow channel; The first charging electrode and the second charging electrode are electrodes of the same U-shape. When the flow channel substrate and the sealing substrate are bonded, the first charging electrode and the second charging electrode are symmetrically arranged with the droplet delivery channel as the center line, and the bottoms of the first charging electrode and the second charging electrode are arranged close to the droplet delivery channel, and the U-shaped openings are arranged away from the droplet delivery channel.

6. The microfluidic chip based on a dual-electrode group according to claim 1 or 2, characterized in that: The first charging electrode and the second charging electrode are prepared by a lift-off process.

7. The microfluidic chip based on a dual-electrode group according to claim 4, characterized in that: The first charging electrode, the second charging electrode, the first electrode interface and the second electrode interface are formed by stacking silicon oxide-aluminum from the bottom layer upwards.

8. The microfluidic chip based on a dual-electrode group according to claim 1 or 2, characterized in that: The cross intersection is suitable for connecting to the first continuous phase flow channel upward, connecting to the second continuous phase flow channel downward, connecting to the dispersed phase transport flow channel to the left, and connecting to the droplet generation flow channel and the droplet transport flow channel to the right in sequence.

9. A dual-electrode group charging system suitable for the microfluidic chip according to any one of claims 1 to 8, wherein the microfluidic chip is formed by bonding a flow channel substrate and a sealing substrate, characterized in that: include: a first electrode flow channel and a second electrode flow channel provided on the flow channel substrate, and a first charging electrode and a second charging electrode provided on the sealing substrate; The first charging electrode and the second charging electrode have the same electrode shape as the first electrode flow channel and the second electrode flow channel when the flow channel substrate and the sealing substrate are bonded; The flow channel substrate is further provided with a droplet generation flow channel and a droplet transport flow channel, and the first electrode flow channel and the second electrode flow channel are symmetrically arranged on both sides of the droplet transport flow channel to respectively pass the first conductive solution and the second conductive solution; The first charging electrode and the second charging electrode are suitable for providing a charging voltage to the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution in the droplet generation flow channel and the droplet transport flow channel; the dispersed phase conductive solution generates charged droplets through the electrostatic induction.

10. The dual-electrode group charging system for a microfluidic chip according to claim 9, wherein: The first charging electrode and the second charging electrode are also suitable for directly providing the charging voltage to the dispersed phase conductive solution in the droplet generation channel and the droplet transport channel when the first conductive solution and the second conductive solution are lacking in the first electrode flow channel and the second electrode flow channel, so as to cause electrostatic induction of the dispersed phase conductive solution.

11. The dual-electrode group charging system for a microfluidic chip according to claim 9 or 10, characterized in that: The sealing substrate is further provided with: a first electrode interface and a second electrode interface; the first charging electrode and the second charging electrode are respectively provided with the first electrode interface and the second electrode interface at both ends.

12. The dual-electrode group charging system for a microfluidic chip according to claim 9 or 10, characterized in that: The first electrode flow channel and the second electrode flow channel are U-shaped flow channels symmetrically arranged with the droplet delivery flow channel as the center line; the bottoms of the first electrode flow channel and the second electrode flow channel are arranged close to the droplet delivery flow channel, and the U-shaped openings are arranged away from the droplet delivery flow channel; The first charging electrode and the second charging electrode are electrodes of the same U-shape. When the flow channel substrate and the sealing substrate are bonded, the first charging electrode and the second charging electrode are symmetrically arranged with the droplet delivery channel as the center line, and the bottoms of the first charging electrode and the second charging electrode are arranged close to the droplet delivery channel, and the U-shaped openings are arranged away from the droplet delivery channel.

13. The dual-electrode group charging system for a microfluidic chip according to claim 9 or 10, characterized in that: The first charging electrode and the second charging electrode are prepared by a lift-off process.

14. The dual-electrode group charging system for a microfluidic chip according to claim 12, wherein: The first charging electrode, the second charging electrode, the first electrode interface and the second electrode interface are formed by stacking silicon oxide-aluminum from the bottom layer upwards.

15. A method for preparing the microfluidic chip according to any one of claims 1 to 8, characterized in that: include: Prepare a chip positive mold based on a single crystal silicon wafer to obtain a positive mold for a microfluidic system; The microfluidic channel system includes: a dispersed phase delivery channel, a first continuous phase flow channel and a second continuous phase flow channel, a droplet generation flow channel, a droplet delivery flow channel, a first electrode flow channel and a second electrode flow channel; Performing a hydrophobic treatment on the positive mold of the microfluidic channel system; pouring the prepared flow channel substrate material into the microfluidic system male mold 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; preparing a charging electrode pattern on a packaging substrate material; Based on the charging electrode pattern, thin-film metal electrodes of a first charging electrode and a second charging electrode are prepared on the packaging substrate material to form a packaging substrate; the first charging electrode and the second charging electrode have the same electrode shape as the first electrode flow channel and the second electrode flow channel; The flow channel is packaged based on the prepared flow channel substrate and packaging substrate to obtain a microfluidic chip.

16. 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: cleaning the single crystal silicon wafer; Performing surface hydrophilic treatment on the cleaned single crystal silicon wafer; 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; The silicon wafer is placed on a heating table for pre-baking, and a mask with a pre-designed flow channel system is placed on a film-curing rack of a photolithography machine; Performing photolithography on the silicon wafer using a photolithography machine; 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 a chip positive mold.

17. The method for preparing a microfluidic chip according to claim 16, wherein: The cleaning 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.

18. The method for preparing a microfluidic chip according to claim 16, wherein: The hydrophilic treatment of the surface of the cleaned single crystal silicon wafer comprises: placing the cleaned single crystal silicon wafer with its surface facing upward in a plasma cleaning machine to complete the cleaning treatment.

19. The method for preparing a microfluidic chip according to claim 15, wherein: The hydrophobic treatment of the microfluidic system male mold comprises: 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.

20. The method for preparing a microfluidic chip according to claim 15, wherein: The process of pouring the prepared flow channel substrate material into the microfluidic system male mold to prepare the microfluidic system of the flow channel substrate comprises: 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 microfluidic system was prepared.

21. The method for preparing a microfluidic chip according to claim 15, wherein: The step of preparing a charging electrode pattern on a packaging substrate material comprises: Cleaning the packaging substrate material; Performing surface hydrophilic treatment on the cleaned packaging substrate material; injecting photoresist at the center of the packaging substrate material; Place the packaging substrate material with photoresist on the chuck of the coating machine, use the coating machine to spin-coat the photoresist and complete the pre-baking of the packaging substrate material; Placing the pre-baked packaging substrate material under a pre-baked film designed with a desired charging electrode pattern, and photolithography the packaging substrate material using a photolithography machine; Post-baking the package substrate material after photolithography; After the post-baking is completed, the packaging substrate material is developed at room temperature until no white precipitate appears; The packaging substrate material is cleaned and dried.

22. The method for preparing a microfluidic chip according to claim 21, wherein: The cleaning of the packaging substrate material includes: ultrasonically cleaning the packaging substrate material with acetone, anhydrous ethanol and deionized water for 15 minutes respectively, taking it out and blowing it dry with a nitrogen gun, placing it on a hot plate at room temperature, slowly heating it to 120° C. and heating it for 30 minutes, and drying it to obtain a dry packaging substrate material.

23. The method for preparing a microfluidic chip according to claim 21, wherein: The performing surface hydrophilic treatment on the cleaned packaging substrate material includes placing the packaging substrate material in a plasma cleaning machine for surface activation.

24. The method for preparing a microfluidic chip according to claim 15, wherein: The method of preparing thin-film metal electrodes of the first charging electrode and the second charging electrode on the packaging substrate material based on the charging electrode pattern to form a packaging substrate includes: placing the obtained packaging substrate material with a pattern in a magnetron sputtering machine, first sputtering a first layer of silicon oxide film, then sputtering an aluminum film, and finally taking out the coated packaging substrate material.

25. The method for preparing a microfluidic chip according to claim 24, wherein: The thickness of the first silicon oxide film is 150 nm, and the thickness of the aluminum film is 100 nm.

26. The method for preparing a microfluidic chip according to claim 15, wherein: Also includes: The packaging substrate material having the first charging electrode and the second charging electrode is allowed to stand, rinsed and dried to prepare the packaging substrate.

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