CN115970779A

CN115970779A - Micro-fluidic chip based on double electrode groups, charging system and preparation method of charging system

Info

Publication number: CN115970779A
Application number: CN202310044407.3A
Authority: CN
Inventors: 请求不公布姓名
Original assignee: Shanghai Weiran Technology Co ltd
Current assignee: Shanghai Weiran Technology Co ltd
Priority date: 2023-01-30
Filing date: 2023-01-30
Publication date: 2023-04-18

Abstract

The invention provides a micro-fluidic chip based on a double-electrode group, a charging system and a preparation method of the charging system. The microfluidic chip includes: a dispersed phase conveying flow channel, a first continuous phase flow channel, a second continuous phase flow channel, a liquid drop generating flow channel, a liquid drop conveying flow channel, a first electrode flow channel, a second electrode flow channel, a first charging electrode and a second charging electrode; the first charging electrode and the second charging electrode have the same shape as the first electrode flow passage and the second electrode flow passage when the flow passage substrate and the sealing substrate are bonded; the first charging electrode and the second charging electrode are suitable for providing charging voltage for the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel so as to enable the dispersed phase conductive solution in the droplet generation flow channel and the droplet conveying flow channel to be subjected to electrostatic induction; the dispersed phase conductive solution generates charged droplets through the electrostatic induction. The invention can improve the charging structure of the microfluidic technology and improve the efficiency of generating the liquid drops and charging the liquid drops.

Description

Micro-fluidic chip based on double electrode groups, charging system and preparation method of charging system

Technical Field

The invention relates to the technical field of microfluidics, in particular to a microfluidic chip based on a double-electrode group, a double-electrode group charging system based on the microfluidic chip and a preparation method of the microfluidic chip.

Background

Microfluidic technology has many advantages, such as: the characteristics of high efficiency, small reagent consumption, small volume, no pollution and the like enable the droplet microfluidic technology to be developed rapidly from nothing to nothing. The micro-fluidic technology based on the liquid drops aims to construct discrete micro-liquid drops through incompatible multi-phase fluids, the mutually independent property of the micro-liquid drops can ensure that biochemical reaction is carried out in a micro-liquid environment like a compartment, digitization and programmability can be realized, and a platform is provided for solving the research problem which is very challenging in the aspect of biochemical medical treatment.

In view of the advantages of little reagent consumption, good uniformity, higher specific surface area and independent control in the micro-droplet technology, the micro-droplet becomes an important experimental platform in biological, chemical, medical and material preparation and application. Complex biochemical research usually involves a series of complex processing procedures such as encapsulation, mixing, reaction and measurement of a droplet sample, and accurate droplet manipulation techniques such as droplet sorting, splitting, fusion, capture and release will make these complex processing procedures more convenient and simpler, and in order to complete the above operations on the droplets, various methods are currently used for processing, such as: acoustic-based methods, magnetic-based methods, thermal-based methods, electrical-based methods, etc., wherein the electrical-based methods are the most feasible method for droplet operations due to their advantages of fast response, high controllability, good compatibility, easy implementation, etc.

At present, liquid drops are operated by an electrical method, and researchers have used dielectrophoresis, electrowetting, electrostatic method, etc. to separate, combine and efficiently sort the liquid drops, wherein: the dielectrophoresis method has simple structure but lower operation efficiency on liquid drops and smaller generated dielectrophoresis force; the electrowetting method is to change the wettability of the surface of the microfluidic chip by changing voltage to finish the operation on liquid drops, has low operation efficiency and is difficult to realize high-speed and stable liquid drop operation; although the electrostatic method can stably perform the droplet operation, the charging structure of the chip related to the electrostatic method to the droplet is complicated in the present stage, and a special electrode needs to be arranged to contact the droplet, which is difficult to implement. In general, there is no way in the above-mentioned droplet operation methods to achieve the effects of conciseness, high efficiency, rapidity, and no pollution at the same time.

The chinese patent publication No. CN103865795B discloses a micro-fluidic chip for cell sorting by voltage control in 6 th and 18 th 2014, relates to a micro-fluidic chip for cell sorting by voltage control, and belongs to the field of micro-fluidic chips. The voltage control cell sorting microfluidic chip comprises: a droplet generating section, a charging section, a voltage control section, and a droplet collecting section; the liquid drop generating part comprises a sodium alginate channel and an oil channel vertical to the sodium alginate channel; the charging part comprises a sodium alginate channel and charging electrodes distributed on two sides of the sodium alginate channel; the voltage control part comprises two sodium alginate sub-channels which are connected with the sodium alginate channel, and a triangular wedge is arranged at the connection point; charging electrodes are distributed on two sides of the two sodium alginate sub-channels, and the sodium alginate sub-channels are connected with an oil injection pipeline before entering the charging electrodes.

Although the voltage control cell sorting microfluidic chip provides a structure for independently generating liquid drops and charging the liquid drops, the structure can finish the generation and charging of the liquid drops, but has various defects, and the specific defects are as follows:

1. the liquid drop chip charging structure is complex, and the liquid drop chip charging structure is composed of a metal film electrode, and the preparation of the metal electrode on a substrate is needed, so that the preparation process is complex, and the difficulty in chip preparation is increased.

2. The technical scheme adopts non-contact charging, when two or more liquid drops exist in a charging area of the microfluidic chip disclosed by the invention, the charging of a single liquid drop cannot be finished, the generated electric quantity is small, the charged electric quantity of the liquid drop is small, and the charging effect is low; and the microfluidic chip is difficult to realize the controllable charging of a single liquid drop as required and cannot be fully controlled, so that the liquid drop has the characteristics of positive electricity, negative electricity and no electricity.

3. According to the technical scheme, single liquid drop charging is difficult to realize after the liquid drop microfluidic chip generates the liquid drops, the generation of the liquid drops is separated from a charging structure, when two liquid drops exist in an area, the two liquid drops are charged simultaneously, and the single charging cannot be realized.

4. According to the technical scheme, the chip is charged and separated from the generated liquid drops, the liquid drop generation and the liquid drop charging cannot be completed simultaneously, and the chip structure is very complex.

Disclosure of Invention

The technical problem solved by the technical scheme of the invention is as follows: how to improve the charging structure of the microfluidic technology and improve the efficiency of generating and charging the liquid drops.

In order to solve the above technical problems, the present invention provides a microfluidic chip based on dual electrode sets, including: the sealing structure comprises a runner substrate and a sealing substrate, wherein the runner substrate is provided with: a dispersed phase conveying flow channel, a first continuous phase flow channel, a second continuous phase flow channel, a liquid drop generating flow channel, a liquid drop conveying flow channel, a first electrode flow channel and a second electrode flow channel;

the dispersed phase conveying flow channel is suitable for conveying a dispersed phase conductive solution, the first continuous phase flow channel and the second continuous phase flow channel are suitable for conveying a first continuous phase fluid and a second continuous phase fluid respectively, and the dispersed phase conveying flow channel, the first continuous phase flow channel and the second continuous phase flow channel are connected in a cross mode to form a cross position, so that the dispersed phase conductive solution is intersected with the first continuous phase flow channel and the second continuous phase flow channel at the cross position to enter the droplet generation flow channel; the dispersed phase conductive solution is subjected to the shearing force of the first continuous phase fluid and the second continuous phase fluid in the droplet generation flow channel so as to generate wrapped droplets in the droplet generation flow channel; the droplet generation channel is adapted to connect to the droplet delivery channel, which is connected to a droplet collection port;

the first electrode runner and the second electrode runner are suitable for being symmetrically arranged at two sides of the liquid drop conveying runner so as to be respectively introduced with a first conductive solution and a 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 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 charging voltage for the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel so as to enable the dispersed phase conductive solution in the droplet generation flow channel and the droplet conveying flow channel to be subjected to electrostatic induction; the dispersed phase conductive solution generates charged droplets through the electrostatic induction.

Optionally, the first and second charging electrodes are further adapted to directly provide the charging voltage to the disperse phase conductive solution in the droplet generation flow channel and the droplet transportation flow channel when the first and second conductive solutions are absent in the first and second electrode flow channels, so as to induce the static electricity of the disperse phase conductive solution.

Optionally, the flow channel substrate is further provided with: the device comprises 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 a droplet collection port; one end of the disperse phase conveying flow channel is connected to the disperse phase inlet to access the disperse phase conductive solution, and the other end of the disperse phase conveying flow channel is connected to the cross; one end of each of the first continuous phase flow channel and the second continuous phase flow channel is connected to the first continuous phase inlet and the second continuous phase inlet respectively so as to be connected to the first continuous phase fluid and the second continuous phase fluid respectively, and the other end of each of the first continuous phase flow channel and the second continuous phase flow channel is connected to the cross; one end of the first electrode flow channel and one end of the second electrode flow channel are respectively connected to the first conductive solution inlet and the second conductive solution inlet, and the other end of the first electrode flow channel and the other end of the second electrode flow channel are respectively connected to the first exhaust port and the second exhaust port;

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 liquid drop collecting outlet joint are correspondingly coaxially matched with and communicated with the dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet and the liquid drop collecting port.

Optionally, the sealing substrate further includes: a first electrode interface and a second electrode interface; and the first electrode interface and the second electrode interface are respectively arranged at two ends of the first charging electrode and the second charging electrode.

Optionally, the first electrode channel and the second electrode channel are U-shaped channels symmetrically arranged with the droplet delivery channel as a central line; the bottoms of the first electrode flow channel and the second electrode flow channel are close to the liquid drop conveying flow channel, and the U-shaped opening is far away from the liquid drop conveying flow channel;

the first charging electrode and the second charging electrode are U-shaped electrodes, when the flow channel substrate and the sealing substrate are bonded, the first charging electrode and the second charging electrode are symmetrically arranged by taking the liquid drop conveying flow channel as a central line, the bottoms of the first charging electrode and the second charging electrode are close to the liquid drop conveying flow channel, and the U-shaped opening is far away from the liquid drop conveying flow channel.

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

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 a bottom layer to an upper layer.

Optionally, the cross is adapted to be connected to the first continuous phase channel upwards, connected to the second continuous phase channel downwards, connected to the dispersed phase conveying channel leftwards, and connected to the droplet generation channel and the droplet conveying channel rightwards in sequence.

In order to solve the above technical problems, the present invention further provides a dual-electrode-set charging system suitable for a microfluidic chip, wherein the microfluidic chip is formed by bonding a flow channel substrate and a sealing substrate, and the dual-electrode-set charging system comprises: the first electrode flow channel and the second electrode flow channel are arranged on the flow channel substrate, and the first charging electrode and the second charging electrode are arranged on the sealing substrate; the first charging electrode and the second charging electrode have the same 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 channel substrate is also provided with a liquid drop generating channel and a liquid drop conveying channel, and the first electrode channel and the second electrode channel are symmetrically arranged on two sides of the liquid drop conveying channel so as to be respectively introduced with a first conductive solution and a second conductive solution;

the first charging electrode and the second charging electrode are the same U-shaped electrode, when the flow channel substrate and the sealing substrate are bonded, the first charging electrode and the second charging electrode are symmetrically arranged by taking the liquid drop conveying flow channel as a central line, the bottoms of the first charging electrode and the second charging electrode are close to the liquid drop conveying flow channel, and the U-shaped opening is far away from the liquid drop conveying flow channel.

In order to solve the technical problem, the technical scheme of the invention also provides a preparation method of the microfluidic chip, which comprises the following steps:

preparing a chip male die based on a monocrystalline silicon wafer to obtain a micro-channel system male die; the micro flow channel system includes: a dispersed phase conveying flow channel, a first continuous phase flow channel, a second continuous phase flow channel, a droplet generation flow channel, a droplet conveying flow channel, a first electrode flow channel and a second electrode flow channel;

carrying out hydrophobization treatment on the male die of the micro-channel system;

pouring the material of the prepared flow channel substrate into the micro-flow channel system male die to prepare the micro-flow channel system of the flow channel substrate;

cooling the prepared flow channel substrate and cutting and punching a micro-flow channel system of the flow channel substrate to prepare and obtain the required flow channel substrate;

preparing a charging electrode pattern on a packaging substrate material;

preparing thin film metal electrodes of a first charging electrode and a second charging electrode on the packaging substrate material based on the charging electrode pattern to form a packaging substrate; the first charging electrode and the second charging electrode are the same as the first electrode flow channel and the second electrode flow channel in electrode shape;

and (4) carrying out flow channel packaging based on the prepared flow channel substrate and the packaging substrate to obtain the micro-fluidic chip.

Optionally, the preparation of the chip male mold based on the monocrystalline silicon wafer includes:

cleaning the monocrystalline silicon wafer;

carrying out surface hydrophilic treatment on the cleaned monocrystalline silicon wafer;

injecting photoresist at the central position of the monocrystalline silicon piece, placing the silicon piece with the photoresist above a sucker of a spin coater, and spin-coating the photoresist by using the spin coater;

placing the silicon wafer on a heating table for pre-baking, and placing a mask with a pre-designed flow channel system on a mask curing frame of a photoetching machine;

photoetching the silicon wafer by using a photoetching machine;

and after photoetching, post-baking and developing the silicon wafer, finally drying the silicon wafer by using nitrogen, and placing the silicon wafer on a heating table again for hardening and baking to obtain a chip male die.

Optionally, the cleaning the monocrystalline silicon wafer includes:

placing the monocrystalline silicon piece in a piranha solution and heating;

and respectively ultrasonically cleaning the heated monocrystalline silicon wafer for 15min by using acetone, absolute ethyl alcohol and deionized water, taking out the monocrystalline silicon wafer, blow-drying the monocrystalline silicon wafer by using a nitrogen gun, and placing the monocrystalline silicon wafer on a 120-degree hot plate for heating for 30min to completely dry the monocrystalline silicon wafer.

Optionally, the performing surface hydrophilic treatment on the cleaned monocrystalline silicon wafer includes: and (4) putting the cleaned monocrystalline silicon piece with the surface facing upwards in a plasma cleaning machine to finish cleaning treatment.

Optionally, the hydrophobizing the male mold of the micro flow channel system includes:

and placing the obtained micro-channel system male die into a volatilization cylinder, dripping three drops of perfluoro-decyl-triethoxysilane into the volatilization cylinder, sealing, and placing the volatilization cylinder into an oven for heating and baking.

Optionally, the micro flow channel system for preparing the flow channel substrate by pouring the material of the prepared flow channel substrate into the micro flow channel system male mold comprises:

uniformly mixing the PDMS prepolymer and a curing agent according to a weight ratio of 10.

Optionally, the preparing the charging electrode pattern on the packaging substrate material includes:

cleaning the packaging substrate material;

carrying out surface hydrophilic treatment based on the cleaned packaging substrate material;

injecting photoresist at the central position of the packaging substrate material;

placing a packaging substrate material with photoresist above a spin coater sucker, spin-coating the photoresist by using the spin coater and finishing prebaking the packaging substrate material;

placing the packaging substrate material subjected to pre-baking under a pickling film designed with a required charging electrode pattern, and photoetching the packaging substrate material by using a photoetching machine;

post-baking the packaging substrate material after photoetching;

after the post-baking is finished, developing the packaging substrate material at room temperature until no white precipitate appears;

the packaging substrate material is cleaned and dried.

Optionally, the cleaning the packaging substrate material includes: and respectively ultrasonically cleaning the packaging substrate material for 15min by using acetone, absolute ethyl alcohol and deionized water, taking out, drying by using a nitrogen gun, placing on a hot plate at normal temperature, slowly heating to 120 ℃, heating for 30min, and drying to obtain the dried packaging substrate material.

Optionally, the performing surface hydrophilic treatment based on the cleaned packaging substrate material includes: and placing the packaging substrate material in a plasma cleaning machine for surface activation.

Optionally, the preparing the 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: and placing the obtained packaging substrate material with the pattern in a magnetron sputtering machine, firstly 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 packaging substrate material.

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

Optionally, the method for preparing the microfluidic chip further comprises: and standing, washing and drying the packaging substrate material with the first charging electrode and the second charging electrode to prepare the packaging substrate.

The technical scheme of the invention at least comprises the following beneficial effects:

the microfluidic chip provided by the technical scheme of the invention adopts a double-charging system of the liquid electrode and the charging electrode, has a simple structure, can realize simultaneous generation of liquid drops and charging of the liquid drops by utilizing a double-electrode group structure of the liquid electrode and the charging electrode, simplifies the preparation process of the liquid drop charging microfluidic chip, provides a high-efficiency operation mode for the microfluidic control of the liquid drops, and greatly improves the manufacturing and using efficiency.

The microfluidic chip provided by the technical scheme of the invention can be charged as required after generating the liquid drops, so that the generated liquid drops can have electric charges on the surfaces; the technical scheme of the invention can greatly enhance the operability of the droplet microfluidic chip and greatly enhance the operability of the droplet microfluidic chip on droplet splitting, deflection, movement, fusion and the like.

According to the technical scheme, the liquid drops generated by the liquid drop micro-fluidic chip can be positively charged, negatively charged or uncharged as required; the liquid drops are further charged as required while being generated, so that the related liquid drop products are higher in practicability.

Drawings

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

fig. 1 is a schematic structural diagram of a microfluidic chip according to a technical solution of the present invention;

fig. 2 is a schematic diagram of a charging electrode structure of the microfluidic chip according to the present disclosure;

FIG. 3 is a schematic diagram of a micro channel system of the microfluidic chip according to the present invention;

FIG. 4 is a schematic diagram of the working state of a micro flow channel system based on dual-electrode-set charging according to the present invention;

fig. 5 is a schematic diagram of the dimension 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;

FIG. 6 is a schematic view of a joint structure of a micro flow channel system according to the present invention;

fig. 7 is a schematic structural diagram of a two-electrode-set charging system of a microfluidic chip according to an embodiment of the present invention;

fig. 8 is a schematic flow chart illustrating steps of a method for manufacturing a microfluidic chip according to an embodiment of the present invention.

Detailed Description

In order to better and clearly show the technical scheme of the invention, the invention is further explained by combining the attached drawings.

Example one

The embodiment provides a microfluidic chip based on a double electrode group, which can simultaneously realize droplet generation and droplet charging, and is formed by bonding a flow channel substrate and a sealing substrate as shown in fig. 1, and a flow channel inlet of the chip is connected with a corresponding connector. Specifically, the method comprises the following steps:

dispose the microchannel system on the runner substrate, this microchannel system 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.

The disperse phase transport flow channel 104 is connected to the disperse phase inlet 101, the disperse phase conductive solution can be introduced into the disperse phase transport flow channel 104 from the disperse phase inlet 101, and the disperse phase transport flow channel 104 is adapted to transport the disperse phase conductive solution.

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, and a 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.

With continued reference to fig. 1, the dispersed phase transport channel 104 is criss-crossed with the continuous phase channel 105 and the continuous phase channel 106 to form a crisscross where the dispersed phase conductive solution in the dispersed phase transport channel 104 meets the continuous phase fluid in the continuous phase channel 105 and the continuous phase channel 106. More specifically, the cross may be oppositely connected to the continuous phase flow channel 105 upward, the continuous phase flow channel 106 downward, the dispersed phase transport flow channel 104 leftward, and the droplet generation flow channel 107 rightward in the direction shown in fig. 1. The dispersed phase conductive solution in the dispersed phase conveying flow channel 104, the continuous phase fluid in the continuous phase flow channel 105 and the continuous phase fluid in the continuous phase flow channel 106 enter the droplet generation flow channel 107 simultaneously after meeting at the cross. In the droplet forming flow channel 107, the dispersed phase conductive solution is subjected to shear force of the continuous phase fluid and surface tension thereof, and is broken to generate a coated droplet.

With continued reference to fig. 1, the 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 channels

109 and 110 are symmetrically disposed on two sides of the droplet transport channel 108, and are respectively filled with a first conductive solution and a second conductive solution.

The sealing substrate of fig. 1 is provided with, corresponding to the electrode flow path 109 and the electrode flow path 110: a charging electrode 201 and a charging electrode 202. The charging

electrodes

201 and 202 may have the same electrode shape as the

electrode flow paths

109 and 110, or may have the same planar structure. When the flow channel substrate and the sealing substrate are bonded, an electrode group consisting of the charging electrode 201 and the charging electrode 202 is arranged opposite to an electrode group consisting of the electrode flow channel 109 and the electrode flow channel 110 (the plane projection structure and the position between the reference electrode groups are the same), so that a double-electrode group of the microfluidic chip in the technical scheme of the invention is formed.

More specifically, when the microfluidic chip shown in fig. 1 is used, the charging electrode 201 and the charging electrode 202 can provide charging voltage for the electrode channel 109 and the electrode channel 110. If the first conductive solution and the second conductive solution are introduced into the electrode flow path 109 and the electrode flow path 110, the conductive solutions in the electrode flow path 109 and the electrode flow path 110 are charged under the charging voltage provided by the charging electrode 201 and the charging electrode 202, and the dispersed phase conductive solution in the droplet generation flow path 107 and the droplet transport flow path 108 is electrostatically induced. If the first conductive solution and the second conductive solution do not exist in the

electrode channels

109 and 110, i.e. the

electrode channels

109 and 110 lack the corresponding conductive solutions, the charging

electrodes

201 and 202 can directly provide the charging voltage for the disperse phase conductive solution in the droplet generation channels 107 and the droplet transport channels 108, so that the disperse phase conductive solution in the droplet generation channels 107 and the droplet transport channels 108 is electrostatically induced. The dispersed phase conductive solution in the droplet generation flow path 107 and the droplet transport flow path 108 can generate charged droplets by electrostatic induction.

Referring to fig. 2, the charging electrode 201 and the charging electrode 202 on the sealing substrate further include: the electrode interface is connected to power so that the charging electrode 201 and the charging electrode 202 can generate a charging voltage. Specifically, both ends of the charging electrode 201 are respectively provided with an electrode interface 203a and an electrode interface 203b, and both ends of the charging electrode 202 are respectively provided with an electrode interface 204a and an electrode interface 204b.

The charging electrode 201 and the charging electrode 202 can be prepared by a Lift-Off process. The charging electrode 201 and the charging electrode 202, and the electrode interface 203a and the electrode interface 203b, the electrode interface 204a and the electrode interface 204b of the charging electrode 201 and the charging electrode 202 may be formed by stacking silicon oxide-aluminum from the bottom layer to the top layer based on a sealing substrate.

In conjunction with fig. 3, the flow channel substrate may further include: a dispersed phase inlet 101, a continuous phase inlet 102, a continuous phase inlet 103, a conducting solution inlet 1091, an exhaust 1092, a conducting solution inlet 1111, an exhaust 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 conveying flow passage 104, the continuous phase flow passage 105 and the continuous phase flow passage 106, and the dispersed phase conveying flow passage 104, the continuous phase flow passage 105 and the continuous phase flow passage 106 introduce corresponding dispersed phase conductive solution and continuous phase fluid through the dispersed phase inlet 101, the continuous phase inlet 102 and the continuous phase inlet 103. At the cross, the droplets are generated in the droplet-generating channels 107 while the introduced dispersed phase conductive solution and continuous phase fluid enter the droplet-generating channels 107. These droplets enter the droplet transport flow path 108 through the droplet generation flow path 107 and generate charged droplets by electrostatic induction.

With continued reference to fig. 3, the

electrode channels

109 and 110 are U-shaped channels symmetrically disposed about the droplet transport channel 108. The U-shaped channel bottoms of the

electrode channels

109 and 110 are disposed close to the droplet transport channels 108, and the U-shaped openings are disposed away from the droplet transport channels. The conducting solution inlet 1091 and the exhaust port 1092 are disposed at two ends of the U-shaped channel of the electrode channel 109, and the conducting solution inlet 1111 and the exhaust port 1112 are disposed at two ends of the U-shaped channel of the electrode channel 110.

As can be seen from fig. 2, the charging

electrodes

201 and 202 are also U-shaped electrodes, like the

electrode channels

109 and 110. The electrode interface 203a and the electrode interface 203b are respectively disposed at two ends of the U-shaped electrode opening of the charging electrode 201, and the electrode interface 204a and the electrode interface 204b are respectively disposed at two ends of the U-shaped electrode opening of the charging electrode 202. When the flow channel substrate and the sealing substrate are bonded, the charging electrode 201 and the charging electrode 202 are also symmetrically arranged with the droplet transport flow channel 108 as a center line, the U-shaped electrode bottoms of the charging electrode 201 and the charging electrode 202 are arranged close to the droplet transport flow channel 108, and the U-shaped opening and the electrode interfaces at both ends are arranged far away from the droplet transport flow channel 108.

When the conductive solution enters the electrode channel 109 and the electrode channel 110 through the conductive solution inlet 1091 and the conductive solution inlet 1111, the electrode channel 109 and the electrode channel 110 are filled with the conductive solution. At this time, the charging

electrodes

201 and 202 are electrically connected through the

electrode ports

203a and 203b, the

electrode ports

204a and 204b, and the charging

electrodes

201 and 202 supply the charging voltage to the

electrode flow paths

109 and 110 to turn the

electrode flow paths

109 and 110 into liquid electrodes, thereby inducing static electricity to the droplets entering the droplet transport flow path 108 through the droplet generation flow path 107.

The conductive solution in the electrode flow channel 109 and the electrode flow channel 110 may also be evacuated through the exhaust port 1092 and the exhaust port 1112, if the conductive solution does not exist in the electrode flow channel 109 and the electrode flow channel 110, the charging electrode 201 and the charging electrode 202 are connected to power through the electrode interface, and the charging electrode 201 and the charging electrode 202 may be directly used as the charging electrode to perform electrostatic induction on the droplets entering the droplet transport flow channel 108 through the droplet generation flow channel 107, so as to charge the droplets.

Referring to fig. 4, in the micro flow channel system of the present embodiment, the dispersed phase transport channel 104 is connected to the continuous phase channel 105 and the continuous phase channel 106 in a cross manner to form a cross, and the cross is schematically illustrated by a triangle in fig. 4. When the dispersed phase conductive solution is introduced in the dispersed phase transport stream 104, the dispersed phase conductive solution is adapted to intersect the continuous phase fluid in the continuous

phase flow channels

105, 106 at a cross to enter the droplet generation channels. In FIG. 4, the direction of flow a of the dispersed phase conductive solution and the directions of flow b and c of the continuous phase fluid are shown. The dispersed phase conductive solution in the droplet-forming channels 107 is subjected to shear forces from the b-direction and c-direction continuous phase fluids and its own surface tension, and breaks to produce a packed droplet.

With continued reference to fig. 4, the droplet transport channels 108 connect the droplet collection ports. The droplet collection port may be located on the microfluidic chip (see droplet collection port 111 of fig. 3 for details) and configured at the end of the droplet delivery channel 108. The droplet collection end 108 can be connected to a droplet collection port 111 of the microfluidic chip as shown in fig. 3. In other embodiments, the droplet transport channel 108 ports may be further radially divided into a plurality of separation channels adapted to be connected to the droplet collection ports of a plurality of microfluidic chips, respectively.

The micro flow channel system according to the present invention employs a two-electrode set structure, i.e., a liquid electrode set including the electrode flow channel 109 and the electrode flow channel 110, and a charging electrode set including the charging electrode 201 and the charging electrode 202. The technical scheme of the invention provides a charging voltage for the liquid electrode through the charging electrode group, and the positive voltage or the negative voltage of the charging voltage enables the liquid electrode group to be positively or negatively charged

After the liquid electrode is negatively charged, the liquid electrode and the droplets in the disperse phase conductive solution are subjected to electrostatic induction to generate positive charges on the surface of the disperse phase conductive solution, and the generated droplets are positively charged, so that the positively charged droplets (4) in the figure 4 are formed;

after the liquid electrode is positively charged, the liquid electrode and the droplets in the disperse phase conductive solution are subjected to electrostatic induction to generate negative charges on the surface of the disperse phase conductive solution, and the generated droplets are negatively charged, namely, the negatively charged droplets (3) in fig. 4 are formed.

When the micro-fluidic chip is electrified to work, the micro-fluidic chip adopting the technical scheme of the invention is adopted, and the liquid electrode and the liquid drop generation in the cross structure work simultaneously under the charging voltage, so the micro-fluidic chip adopting the technical scheme of the invention can realize the technical effect that the liquid drop generation and the liquid drop charging work simultaneously.

Under the micro-fluidic chip of the technical scheme of the invention, if the conductive solution does not exist in the liquid electrode, because the charging electrode and the liquid electrode have the same plane shape, the charging electrode can directly perform electrostatic induction with the liquid drop in the conductive solution of the disperse phase by providing charging voltage (positive voltage or negative voltage):

after the charging electrode is negatively charged, the charging electrode and the droplets in the disperse phase conductive solution are subjected to electrostatic induction to generate positive charges on the surface of the disperse phase conductive solution, and the generated droplets are positively charged, so that the positively charged droplets (4) in the figure 4 are formed;

after the charging electrode is positively charged, the charging electrode and the droplets in the disperse phase conductive solution are subjected to electrostatic induction to generate negative charges on the surface of the disperse phase conductive solution, and the generated droplets are negatively charged, namely, the negatively charged droplets (3) in fig. 4 are formed.

Therefore, when the micro-fluidic chip is electrified to work, the charging electrode can directly provide charging voltage when the liquid electrode does not contain charging solution, and the charging electrode and the liquid drop generation in the cross structure work simultaneously.

With continuing reference to fig. 4 and with reference to fig. 5 (fig. 5 is a cross-sectional view of a flow channel of the micro flow channel system perpendicular to the liquid flow direction, the depth and width of the flow channel can be seen), in this embodiment, the micro flow channel system suitable for the micro flow chip can also be configured in the following size and shape:

the bottom of the U-shaped channel of the electrode channel 109 is disposed close to the droplet transport channel 108 and the disposition distance S1 is 500 μm, the U-shaped open end of the U-shaped channel is disposed away from the droplet transport channel 108, and the disposition distance S2 between the left-side channel of the U-shaped channel and the continuous phase channel 105 is 2 mm.

Similarly, the U-shaped channel bottom of the electrode channel 110 is disposed close to the droplet transport channel 108 and the disposition distance S3 is 500 μm, the U-shaped opening end of the U-shaped channel is disposed away from the droplet transport channel 108, and the disposition distance S4 between the left side channel of the U-shaped channel and the continuous phase channel 106 is 2 mm.

More specifically, the dispersed phase transport flow channel 104 is a rectangular flow channel, which may have a width of 50 microns and a depth of 50 microns. The continuous phase flow channel 105 and the continuous phase flow channel 106 are rectangular flow channels, and the width of the rectangular flow channel may be 60 micrometers and the depth thereof may be 50 micrometers. The drop generating channels 107 are rectangular channels having a width of 50 microns, a depth of 50 microns and a length of 50 microns (the length k2 of the drop generating channel 107 is also illustrated in fig. 4). The droplet transport channels 108 are rectangular channels having a width of 100 microns and a depth of 50 microns. The electrode flow channel 109 and the electrode flow channel 110 are rectangular flow channels, respectively, and since the electrode flow channel 109 and the electrode flow channel 110 are U-shaped flow channels, the bottom flow channels have a width of 400 micrometers and a depth of 50 micrometers, and the flow channels on both sides have a width of 100 micrometers and a depth of 50 micrometers.

The lengths of the dispersed phase transport channel 104, the continuous phase channel 105, the continuous phase channel 107, and the droplet transport channel 108 are not limited in this embodiment.

It should be noted that:

the micro flow channel system is configured to have a size and a shape as a preferred example provided in this embodiment, and in other embodiments, other sizes may be configured as needed.

In the dimensions of the micro flow channel system, the width and depth of the rectangular flow channel refer to the width and depth indicated in the cross section perpendicular to the flow direction of the flow channel fluid shown in fig. 5, wherein the two electrode flow channels respectively indicate the flow channel depth and flow channel width of the electrode flow channel 109 and the electrode flow channel 110 in fig. 4, and the rectangular flow channel indicates the flow channel depth and flow channel width of the droplet transport flow channel 108. Fig. 4 also illustrates, in conjunction with fig. 4, the rectangular channel width k1 of the dispersed phase transport channel 104. The depth of the rectangular flow channel can be referred to fig. 5, which is the etching depth of the corresponding flow channel on the flow channel substrate. Similarly, the depth of the electrode runner can be referred to in fig. 5, which is the etching depth of the corresponding electrode runner on the runner substrate.

In this embodiment, the material of the flow channel substrate for manufacturing the microfluidic chip may be PDMS (polydimethylsiloxane), glass, or PMMA (polymethyl methacrylate). The encapsulating substrate material may be glass or PMMA.

With reference to fig. 6, in the microfluidic chip according to the technical solution of the present invention, the flow channel substrate may further include: a dispersed phase inlet connection 301, a continuous phase inlet connection 303, a continuous phase inlet connection 302, and a droplet collection outlet connection 304. The dispersed phase inlet connection 301, the continuous phase inlet connection 303, the continuous phase inlet connection 302 and the droplet collection outlet connection 304 may be coaxially fitted and connected through the dispersed phase inlet 101, the continuous phase inlet 102, the continuous phase inlet 103 and the droplet collection port 111, respectively. The dispersed phase inlet contact 301 is a conductive contact made of conductive metal materials such as: aluminum, copper, etc., and may also be a conductive non-metallic material such as: carbon tubes, conductive ceramics, etc. When the disperse phase inlet connection 301 is connected to an external electrode, and the electrode is energized, the conductive fluid in the disperse phase will conduct electricity and induce a fluid in the

electrode channels

109, 110.

Example two

Based on the microfluidic chip shown in fig. 1 to 6, the present embodiment provides a two-electrode-set charging system applicable to the microfluidic chip, as shown in fig. 7, including:

an electrode flow channel 109 and an electrode flow channel 110 provided in the flow channel substrate; and the number of the first and second groups,

a charging electrode 201 and a charging electrode 202 disposed on the sealing substrate.

As can be seen in fig. 7: the charging electrodes 201 and 202 (constituting a charging electrode group) have the same electrode shape as the electrode flow paths 109 and 110 (constituting a liquid electrode group). When the flow channel substrate and the sealing substrate are bonded, the projection of the charging electrode group and the liquid electrode group on the plane of the substrate is consistent. According to the description of the first embodiment, the

electrode channels

109 and 110 are symmetrically disposed on both sides of the droplet transport channel, and the conductive solution can be introduced. The charging

electrodes

201 and 202 can provide a charging voltage to the

electrode channels

109 and 110, so that the

electrode channels

109 and 110 form liquid electrodes under the charging voltage, and the liquid electrodes induce static electricity to the dispersed phase conductive solution in the droplet generation channels and the droplet transportation channels. The dispersed phase conductive solution generates charged droplets by this electrostatic induction. If there is no conductive solution in the electrode flow path 109 and the electrode flow path 110, the charging

electrodes

201 and 202 have the same plane shape as the liquid electrode group, and thus can directly induce static electricity to the conductive solution of the dispersed phase in the droplet generation flow path and the droplet transportation flow path. The charging system of the embodiment can realize two modes of liquid charging based on the double-electrode group.

With continuing reference to fig. 7 in conjunction with the microfluidic chip structures of fig. 1-6, the dual-electrode-set charging system further comprises: sealing the

electrode ports

203a, 203b, 204a and 204b provided on the substrate. The electrode interfaces 203a and 203b are respectively provided at two open ends of the U-shaped electrode of the charging electrode 201, and the

electrode interfaces

204a and 204b are respectively provided at two open ends of the U-shaped electrode of the charging electrode 202.

For the specific technical means of the arrangement, shape, preparation scheme and structure of the charging electrode set and the liquid electrode set of the dual-electrode-set charging system, reference may be made to the first embodiment, which is not described herein again.

EXAMPLE III

Based on the microfluidic chip shown in fig. 1 to 6, this embodiment provides a method for manufacturing a microfluidic chip, and referring to fig. 8, the method includes the following steps:

and S100, preparing a chip male die based on the monocrystalline silicon wafer to obtain a micro-channel system male die.

The specific structure of the micro flow channel system can refer to the first embodiment, and may include: 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.

On the basis of the micro flow channel system, the micro flow channel 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 disperse phase inlet 101, the continuous phase inlet 102, and the continuous phase inlet 103 are sequentially disposed at the flow channel ports of the disperse phase conveying flow channel 104, the continuous phase flow channel 105, and the continuous phase flow channel 106, and introduce the corresponding disperse phase conductive solution and the continuous phase fluid into the disperse phase conveying flow channel 104, the continuous phase flow channel 105, and the continuous phase flow channel 106. The conducting solution inlet 1091 and the exhaust port 1092 are disposed at two ends of the U-shaped channel of the electrode channel 109, and the conducting solution inlet 1111 and the exhaust port 1112 are disposed at two ends of the U-shaped channel of the electrode channel 110. The droplet transport channels 108 are connected at one end to the intersection and at the other end to a droplet collection port 111.

On the basis of the micro flow channel system, the micro flow channel system may further include: a dispersed phase inlet connection 301, a continuous phase inlet connection 303, a continuous phase inlet connection 302, and a droplet collection outlet connection 304. Disperse phase inlet connection 301, continuous phase inlet connection 303, continuous phase inlet connection 302 and droplet collection outlet connection 304 may be coaxially mated with and connected through disperse phase inlet 101, continuous phase inlet 102, continuous phase inlet 103 and droplet collection port 111, respectively. The disperse phase inlet connection 301, the continuous phase inlet connection 303, the continuous phase inlet connection 302, and the droplet collection outlet connection 304 may be connected to an external electrode that, when energized, makes the fluid in the corresponding flow channel electrically conductive.

More specifically, the preparation of the positive die for the chip can be carried out on the basis of a monocrystalline silicon wafer in the following manner: cleaning the monocrystalline silicon wafer; carrying out surface hydrophilic treatment on the cleaned monocrystalline silicon wafer; injecting photoresist at the central position of the monocrystalline silicon wafer, placing the silicon wafer with the photoresist above a sucker of a spin coater, and spin-coating the photoresist by using the spin coater; placing the silicon wafer on a heating table for pre-baking, and placing a mask with a pre-designed flow channel system on a mask pickling frame of a photoetching machine; photoetching the silicon wafer by using a photoetching machine; and after photoetching, carrying out post-baking and developing on the silicon wafer, finally drying the silicon wafer by using nitrogen, and placing the silicon wafer on a heating table again for hardening and baking to obtain a chip male die.

The specific process for cleaning the monocrystalline silicon wafer can be as follows: placing the monocrystalline silicon piece in a piranha solution and heating; and respectively ultrasonically cleaning the heated monocrystalline silicon wafer for 15min by using acetone, absolute ethyl alcohol and deionized water, taking out the monocrystalline silicon wafer, drying the monocrystalline silicon wafer by using a nitrogen gun, and placing the monocrystalline silicon wafer on a 120-degree hot plate for heating for 30min to completely dry the monocrystalline silicon wafer.

The specific process of performing surface hydrophilic treatment on the cleaned monocrystalline silicon wafer can be as follows: and (4) putting the cleaned monocrystalline silicon piece with the surface facing upwards in a plasma cleaning machine to finish cleaning treatment.

With continued reference to fig. 8, the method of preparing a microfluidic chip further comprises:

and step S101, performing hydrophobization treatment on the male mold of the micro-channel system.

In step S101, the specific process of performing the hydrophobization on the male mold of the micro flow channel system may be: and placing the obtained micro-channel system male die into a volatilization cylinder, dripping three drops of perfluoro-decyl-triethoxysilane into the volatilization cylinder, sealing, and placing the volatilization cylinder into an oven for heating and baking.

And S102, pouring the material of the prepared flow channel substrate into the micro-flow channel system male die to prepare the micro-flow channel system of the flow channel substrate.

In step S102, the step of casting the material of the prepared flow channel substrate on the micro flow channel system male mold to prepare the micro flow channel system of the flow channel substrate includes the following steps: uniformly mixing the PDMS prepolymer and a curing agent according to a weight ratio of 10.

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

Step S104, preparing a charging electrode pattern on the packaging substrate material.

In step S104, a charging electrode pattern may be prepared on the packaging substrate material by: cleaning the packaging substrate material; carrying out surface hydrophilic treatment based on the cleaned packaging substrate material; injecting photoresist in the central position of the packaging substrate material; placing a packaging substrate material with photoresist above a spin coater sucker, spin-coating the photoresist by using the spin coater and finishing prebaking the packaging substrate material; placing the packaging substrate material subjected to pre-baking under a pickling film designed with a required charging electrode pattern, and photoetching the packaging substrate material by using a photoetching machine; post-baking the packaging substrate material after photoetching; after the post-baking is finished, developing the packaging substrate material at room temperature until no white precipitate appears; the packaging substrate material is cleaned and dried.

The specific process of cleaning the packaging substrate material can comprise the following steps: and respectively ultrasonically cleaning the packaging substrate material by using acetone, absolute ethyl alcohol and deionized water for 15min, taking out, drying by using a nitrogen gun, placing on a hot plate at normal temperature, slowly heating to 120 ℃, heating for 30min, and drying to obtain the dried packaging substrate material.

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

Step S105, preparing thin film metal electrodes of a first charging electrode and a second charging electrode 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.

In step S105, a thin film metal electrode of a charging electrode may be prepared on the packaging substrate material based on the charging electrode pattern by the following preparation manner: and placing the obtained packaging substrate material with the pattern in a magnetron sputtering machine, firstly 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 packaging substrate material. The first silicon oxide film may have a thickness of 150nm, and the aluminum film may have a thickness of 100nm.

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 placed still, washed and dried to prepare the final packaging substrate.

With continued reference to fig. 8, the method for preparing the microfluidic chip of this embodiment further includes:

and S106, carrying out flow channel packaging based on the prepared flow channel substrate and packaging substrate to obtain the microfluidic chip. The process of encapsulating the flow channel substrate and the encapsulation substrate flow channel can adopt the bonding mode of the prior art, and the details are not repeated here.

Application example

Based on the preparation method of the microfluidic chip shown in fig. 8, the application example provides an application example for preparing the microfluidic chip. The preparation method of the microfluidic chip of the application example comprises the following steps:

cleaning a glass substrate and a monocrystalline silicon wafer and carrying out surface hydrophilic treatment;

preparing a pattern of a charging electrode on the glass substrate;

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;

preparing a chip male die based on the monocrystalline silicon wafer to obtain a micro-channel system male die;

pouring the prepared PDMS material into the micro-channel system male mold to prepare a PDMS micro-channel system;

cooling the micro-channel system of the PDMS, and cutting and punching the micro-channel system to prepare a PDMS substrate;

and bonding the glass substrate with the PDMS substrate.

The glass substrate may be cleaned as follows: and ultrasonically cleaning the glass substrate with acetone, absolute ethyl alcohol and deionized water for 15min respectively, taking out, drying by using a nitrogen gun, placing on a hot plate at normal temperature, slowly heating to 120 ℃, heating for 30min, and drying to obtain the dried glass substrate.

The surface hydrophilic treatment of the glass substrate may be carried out as follows: and placing the glass substrate in a plasma cleaning machine for surface activation.

A pattern of a charging electrode may be prepared on the glass substrate by:

injecting photoresist at a central position of the glass substrate;

placing the glass substrate with the photoresist above a sucker of a spin coater, and spin-coating the photoresist by using the spin coater to complete the prebaking of the glass substrate;

placing the glass substrate subjected to pre-baking under a pickling film designed with a required charging electrode pattern, and photoetching the glass substrate by using a photoetching machine;

post-baking the photoetched glass substrate;

after the post-baking is finished, developing the glass substrate at room temperature until no white precipitate appears;

the glass substrate is washed and dried.

The process of preparing the thin film metal electrode of the charging electrode on the glass substrate based on the above pattern may include: and placing the obtained glass substrate with the pattern in a magnetron sputtering machine, firstly sputtering a first layer of silicon oxide film, then sputtering an aluminum film, and finally taking out the coated glass substrate to obtain the glass substrate. The thickness of the first silicon oxide film is 150nm, and the thickness of the aluminum film is 100nm.

The preparation method of the application example further comprises the following steps:

and standing, washing and drying the glass substrate with the charging electrode to prepare the glass substrate.

The single crystal silicon wafer can be cleaned as follows:

placing the monocrystalline silicon piece in a piranha solution and heating;

The surface hydrophilic treatment can be carried out on the monocrystalline silicon wafer according to the following steps: and (5) putting the cleaned monocrystalline silicon piece with the surface facing upwards in a plasma cleaning machine to finish cleaning treatment.

The preparation of the chip male die based on the monocrystalline silicon wafer comprises the following processes:

injecting photoresist at the central position of a monocrystalline silicon wafer, placing the silicon wafer with the photoresist above a sucker of a spin coater, and spin-coating the photoresist by using the spin coater;

placing a silicon wafer on a heating table for pre-baking, and placing a mask with a pre-designed flow channel system on a mask curing frame of a photoetching machine;

photoetching the silicon wafer by using a photoetching machine;

and after photoetching, post-baking and developing the silicon wafer, finally drying by using nitrogen, and placing the silicon wafer on a heating table again for mold hardening and baking to obtain a chip male mold.

The thickness of the above-mentioned positive die for a chip may be 50 μm.

The hydrophobization treatment of the male die of the micro-channel system comprises the following steps:

The above-mentioned preparing PDMS material pours the said micro flow channel system male mold in order to prepare PDMS micro flow channel system includes:

The glass substrate prepared in this application example can be bonded to a PDMS substrate by the following procedure:

sequentially putting the glass substrate and PDMS into acetone, absolute ethyl alcohol and deionized water, and cleaning for 15min in an ultrasonic cleaning machine respectively to remove impurities on the surfaces of the glass substrate and the PDMS and keep the surfaces clean;

putting the glass substrate into an oxygen plasma cleaning machine, and bombarding for 2min under the power of 120W;

after the glass substrate is bombarded, waiting for the pressure in the cavity to rise to the atmospheric pressure, not taking out the glass substrate, putting PDMS into the cavity of the oxygen plasma cleaning machine, bombarding the PDMS and the glass substrate for 32s under the power of 120W, and then taking out the PDMS;

after the glass substrate and the PDMS are taken out, a few drops of absolute ethyl alcohol are dripped on the surfaces to be bonded of the glass substrate and the PDMS to be used as a lubricant, so that the PDMS slides on the glass substrate until the PDMS is correctly aligned, and the aligned and attached chip is pressed by a rolling brush until air bubbles between the glass substrate and the PDMS are extruded out;

and then, placing the partially bonded glass substrate and PDMS into a vacuum drying oven for air suction to remove the absolute ethyl alcohol and enhance the bonding degree.

The bonded glass substrate and the PDMS substrate can also be placed on a heating platform at 95 ℃ to be heated for 24h so as to remove the absolute ethyl alcohol and enhance the bonding degree.

The foregoing description of specific embodiments of the present invention has been presented. It is to be understood that the present invention is not limited to the specific embodiments described above, and that various changes and modifications may be made by one skilled in the art within the scope of the appended claims without departing from the spirit of the invention.

Claims

1. A dual electrode set-based microfluidic chip comprising: the flow channel substrate and the sealing substrate are characterized in that: a dispersed phase conveying flow channel, a first continuous phase flow channel, a second continuous phase flow channel, a droplet generation flow channel, a droplet conveying flow channel, a first electrode flow channel and a second electrode flow channel;

the dispersed phase conveying flow channel is suitable for conveying a dispersed phase conductive solution, the first continuous phase flow channel and the second continuous phase flow channel are suitable for conveying a first continuous phase fluid and a second continuous phase fluid respectively, and the dispersed phase conveying flow channel, the first continuous phase flow channel and the second continuous phase flow channel are connected in a cross mode to form a cross-shaped intersection, so that the dispersed phase conductive solution is intersected with the first continuous phase flow channel and the second continuous phase flow channel at the cross-shaped intersection to enter the droplet generation flow channel; the dispersed phase conductive solution is subjected to the shearing force of the first continuous phase fluid and the second continuous phase fluid in the droplet generation flow channel so as to generate wrapped droplets in the droplet generation flow channel; the droplet generation channel is adapted to connect to the droplet delivery channel, which is connected to a droplet collection port;

the first electrode flow channel and the second electrode flow channel are suitable for being symmetrically arranged on two sides of the liquid drop conveying flow channel so as to be respectively introduced with a first conductive solution and a second conductive solution;

the first charging electrode and the second charging electrode are suitable for providing charging voltage for the first conductive solution and the second conductive solution in the first electrode flow channel and the second electrode flow channel so as to lead the dispersed phase conductive solution in the liquid drop generating flow channel and the liquid drop conveying flow channel to be subjected to electrostatic induction; the dispersed phase conductive solution generates charged droplets through the electrostatic induction.

2. The dual-electrode-group-based microfluidic chip of claim 1, wherein the first and second charging electrodes are further adapted to directly provide the charging voltage to the dispersed phase conductive solution in the droplet generation channels and droplet transport channels when the first and second conductive solutions are absent in the first and second electrode channels, so as to electrostatically induce the dispersed phase conductive solution.

3. The microfluidic chip based on dual electrode set according to claim 1 or 2, wherein the flow channel substrate further comprises: the device comprises 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 a droplet collection port; one end of the disperse phase conveying flow channel is connected to the disperse phase inlet to access the disperse phase conductive solution, and the other end of the disperse phase conveying flow channel is connected to the cross; one end of each of the first continuous phase flow channel and the second continuous phase flow channel is connected to the first continuous phase inlet and the second continuous phase inlet respectively so as to be connected to the first continuous phase fluid and the second continuous phase fluid respectively, and the other end of each of the first continuous phase flow channel and the second continuous phase flow channel is connected to the cross; one end of the first electrode flow channel and one end of the second electrode flow channel are respectively connected to the first conductive solution inlet and the second conductive solution inlet, and the other end of the first electrode flow channel and the other end of the second electrode flow channel are respectively connected to the first exhaust port and the second exhaust port;

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 and communicated with the dispersed phase inlet, the first continuous phase inlet, the second continuous phase inlet and the droplet collection port.

4. The microfluidic chip based on dual electrode set according to claim 1 or 2, wherein the sealing substrate further comprises: a first electrode interface and a second electrode interface; and the first electrode interface and the second electrode interface are respectively arranged at two ends of the first charging electrode and the second charging electrode.

5. The dual-electrode-group-based microfluidic chip of claim 1, wherein the first electrode channel and the second electrode channel are U-shaped channels symmetrically arranged with the droplet transport channel as a center line; the bottoms of the first electrode flow channel and the second electrode flow channel are close to the liquid drop conveying flow channel, and the U-shaped opening is far away from the liquid drop conveying flow channel;

6. The dual-electrode-group-based microfluidic chip according to claim 1 or 2, wherein the first charging electrode and the second charging electrode are prepared by a Lift-Off process.

7. The dual-electrode-set-based microfluidic chip of claim 4, wherein said first charging electrode, said second charging electrode, said first electrode interface, and said second electrode interface are formed by stacking silica-alumina from bottom to top.

8. The dual-electrode-group-based microfluidic chip according to claim 1 or 2, wherein the cross is adapted to connect to the first continuous-phase flow channel upward, the second continuous-phase flow channel downward, the dispersed-phase delivery flow channel leftward, and the droplet-generating flow channel and the droplet-delivering flow channel rightward in sequence.

9. A double-electrode-group charging system suitable for a micro-fluidic chip, wherein the micro-fluidic chip is formed by bonding a flow channel substrate and a sealing substrate, and the double-electrode-group charging system is characterized by comprising: the first electrode flow channel and the second electrode flow channel are arranged on the flow channel substrate, and the first charging electrode and the second charging electrode are arranged on the sealing substrate; the first charging electrode and the second charging electrode have the same shape as the first electrode flow channel and the second electrode flow channel when the flow channel substrate and the sealing substrate are bonded;

10. The system of claim 9, wherein the first and second charging electrodes are further adapted to directly provide the charging voltage to the dispersed phase conductive solution in the droplet generation channels and droplet transport channels to electrostatically induce the dispersed phase conductive solution in the droplet generation channels and droplet transport channels when the first and second conductive solutions are absent in the first and second electrode channels.

11. The system for charging a two-electrode set suitable for a microfluidic chip according to claim 9 or 10, wherein the sealing substrate further comprises: a first electrode interface and a second electrode interface; and the first electrode interface and the second electrode interface are respectively arranged at two ends of the first charging electrode and the second charging electrode.

12. The system according to claim 9 or 10, wherein the first electrode flow channel and the second electrode flow channel are U-shaped flow channels symmetrically arranged with respect to the droplet transportation flow channel as a center line; the bottoms of the first electrode flow channel and the second electrode flow channel are close to the liquid drop conveying flow channel, and the U-shaped opening is far away from the liquid drop conveying flow channel;

13. The system of claim 9 or 10, wherein the first and second charging electrodes are fabricated by Lift-Off process.

14. The system of claim 12, wherein the first charging electrode, the second charging electrode, the first electrode interface, and the second electrode interface are formed by stacking a silicon oxide-aluminum layer on top of a bottom layer.

15. A method for preparing a microfluidic chip is characterized by comprising the following steps:

pouring the material of the prepared flow channel substrate into the male die of the micro-flow channel system to prepare the micro-flow channel system of the flow channel substrate;

preparing a charging electrode pattern on a packaging substrate material;

preparing thin film metal electrodes of a first charging electrode and a second charging electrode on the packaging substrate material based on the charging electrode pattern to form a packaging substrate; the first charging electrode and the second charging electrode have the same electrode shape as the first electrode flow passage and the second electrode flow passage;

16. The method of manufacturing a microfluidic chip according to claim 15, wherein the performing of the positive die manufacturing of the chip based on the single-crystal silicon wafer comprises:

cleaning the monocrystalline silicon wafer;

placing the silicon wafer on a heating table for pre-baking, and placing a mask with a pre-designed flow channel system on a mask pickling frame of a photoetching machine;

photoetching the silicon wafer by using a photoetching machine;

17. The method for preparing a microfluidic chip according to claim 16, wherein the cleaning the single-crystal silicon wafer comprises:

placing the monocrystalline silicon piece in a piranha solution and heating;

and respectively ultrasonically cleaning the heated monocrystalline silicon wafer for 15min by using acetone, absolute ethyl alcohol and deionized water, taking out the monocrystalline silicon wafer, drying the monocrystalline silicon wafer by using a nitrogen gun, and placing the monocrystalline silicon wafer on a 120-degree hot plate for heating for 30min to completely dry the monocrystalline silicon wafer.

18. The method for preparing a microfluidic chip according to claim 16, wherein the performing surface hydrophilic treatment on the cleaned monocrystalline silicon wafer comprises: and (4) putting the cleaned monocrystalline silicon piece with the surface facing upwards in a plasma cleaning machine to finish cleaning treatment.

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

20. The method of claim 15, wherein the step of casting the material for preparing the flow channel substrate on the male mold for preparing the micro flow channel system comprises:

21. The method of claim 15, wherein the step of forming the charging electrode pattern on the packaging substrate material comprises:

cleaning the packaging substrate material;

injecting photoresist in the central position of the packaging substrate material;

post-baking the packaging substrate material after photoetching;

the packaging substrate material is cleaned and dried.

22. The method of claim 21, wherein the cleaning the packaging substrate material comprises: and respectively ultrasonically cleaning the packaging substrate material for 15min by using acetone, absolute ethyl alcohol and deionized water, taking out, drying by using a nitrogen gun, placing on a hot plate at normal temperature, slowly heating to 120 ℃, heating for 30min, and drying to obtain the dried packaging substrate material.

23. The method of claim 21, wherein the performing surface hydrophilic treatment based on the cleaned packaging substrate material comprises: and placing the packaging substrate material in a plasma cleaning machine for surface activation.

24. The method of claim 15, wherein the step of forming the thin film metal electrodes of the first and second charging electrodes on the packaging substrate material based on the charging electrode pattern to form a packaging substrate comprises: and placing the obtained packaging substrate material with the pattern in a magnetron sputtering machine, firstly 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 packaging substrate material.

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

26. The method of preparing a microfluidic chip according to claim 15, further comprising: and standing, washing and drying the packaging substrate material with the first charging electrode and the second charging electrode to prepare the packaging substrate.