A microfluidic chip

Abstract

The present disclosure provides a microfluidic chip, including a chip body, wherein the chip body is provided with channels running through both ends, the first end of the channel is an inlet channel for liquid input, the second end of the channel is an outlet channel for liquid output, expansion channels and contraction channels are sequentially arranged between the inlet channel and the outlet channel, and the channel width of the expansion channel is greater than that of the inlet channel, the outlet channel and the contraction channel; with the axis of the inlet channel as a reference, one side of the expansion channel and the contraction channel are both arranged flush with the inlet channel on one side of the axis, and the other sides of the expansion channel and the contraction channel are arranged to expand toward the other side of the axis; an electrode is arranged in the expansion channel.

Description

Technical Field

[0001] The present disclosure relates to the field of microfluidic chips, and in particular to a microfluidic chip. Background Art

[0002] Microfluidic chip technology integrates the fundamental operational elements of biological, chemical, and medical analysis, including sample preparation, reaction, separation, and detection, onto a micron-scale chip, automating the entire analytical process. Due to its enormous potential in biology, chemistry, and medicine, it has developed into a new research field at the intersection of biology, chemistry, medicine, fluidics, electronics, materials science, and mechanics. Microfluidic chip technology has multifaceted and multifaceted applications in biology, medicine, materials science, and other fields. Microfluidic chips offer excellent biocompatibility, optical transparency, and large-scale integration, offering new possibilities for scientific research.

[0003] Microfluidic chips can be used as portable point-of-care testing instruments. They have significant application value in diagnosing sudden acute illnesses, early screening and prognostic assessment of malignant diseases, and promoting the development of personalized medicine. As a key vehicle for addressing public health needs, they have received significant attention from governments worldwide in recent years. As a key technology for point-of-care testing, microfluidic chips offer advantages such as fast detection speed, high sensitivity, low cost, and excellent integration. They are highly suited to the technical requirements of point-of-care testing and have become a research hotspot in this field.

[0004] Among them, inertial microfluidics technology uses the inertial effect of fluid to induce cells to migrate in the channel under the action of inertial force to achieve precise manipulation. It has the advantages of simple channel structure, easy operation, and high manipulation precision, and has attracted widespread attention from scholars at home and abroad. However, the inertial effect of fluid is highly dependent on the appearance and size of cells, making it difficult to precisely manipulate cells of high concentration and similar size (such as detecting and capturing circulating tumor cells in the blood). The precise acquisition of such cells is of great application and scientific value for the diagnosis, monitoring and treatment of some major diseases. Therefore, breaking through traditional inertial microfluidics technology, improving the manipulation performance of micro-nano bioparticles, and expanding the scope of biomedical applications of inertial microfluidics will provide a research basis for the early screening and prognostic treatment of major diseases, and provide technical support for the ultimate realization of the industrial application of inertial microfluidics chips.

[0005] Existing chips designed using inertial microfluidics require structural settings to control the inertial motion of biological particles in liquids. Therefore, they often have very long inertial channels and complex contraction and expansion structures, which is time-consuming and labor-intensive. Summary of the Invention

[0006] The present disclosure provides a microfluidic chip to at least solve the above technical problems existing in the prior art.

[0007] In one aspect, the present disclosure provides a microfluidic chip, comprising a chip body, wherein the chip body is provided with channels running through both ends, wherein a first end of the channel is an inlet channel for liquid input, and a second end of the channel is an outlet channel for liquid output, and expansion channels and contraction channels are sequentially arranged between the inlet channel and the outlet channel, wherein the channel width of the expansion channel is greater than that of the inlet channel, the outlet channel, and the contraction channel;

[0008] Taking the axis of the inlet channel as a reference, one side of the expansion channel and the contraction channel are both arranged flush with the inlet channel on one side of the axis, and the other sides of the expansion channel and the contraction channel are arranged to expand toward the other side of the axis;

[0009] Electrodes are arranged in the expansion channel.

[0010] In one embodiment, there are a plurality of electrodes, and each of the electrodes is arranged in parallel and at intervals.

[0011] In one embodiment, the chip body is composed of an upper cover plate and a lower cover plate, and the upper cover plate and the lower cover plate are arranged to cover each other to form the channel;

[0012] The material of the upper cover plate is polydimethylsiloxane, and the material of the lower cover plate is indium tin oxide conductive glass.

[0013] In one embodiment, the electrode is fixed on the lower cover plate and extends from one side of the expansion channel to the other side. The electrode is connected to an external power source through the lower cover plate.

[0014] In one embodiment, the axis of the inlet channel and the axis of the expansion channel are arranged parallel to each other.

[0015] In one embodiment, the contraction channel, the inlet channel, and the outlet channel have the same channel width.

[0016] In one embodiment, the electrode is an inclined straight line, and with the axis of the expansion channel as a reference, the acute angle between the electrode and the axis of the expansion channel is in a range of 70 degrees to 80 degrees.

[0017] In one embodiment, the number of electrodes in the expansion channel is negatively correlated with the number of expansion channels.

[0018] In one embodiment, there are 8-12 electrodes in each expansion channel.

[0019] In one embodiment, the electrodes in each expansion channel are arranged at equal intervals.

[0020] Based on the above solution, the present disclosure has the following beneficial effects:

[0021] (1) After the liquid enters the inlet channel at an initial velocity, it enters the expansion channel with the widest channel width under the action of inertia, and the expansion channel further promotes the separation of particles of different sizes in the liquid to achieve movement paths; electrodes are set in the expansion channel to form a non-uniform electric field, so that the particles are affected by the force of dielectrophoresis in addition to inertia, which can accelerate the separation of particles of different sizes; at the same time, the expansion channel is directly connected to the inlet channel, and the channel width of the expansion channel is the widest. One side of the expansion channel and the contraction channel are set flush with the inlet channel, and only the other side is expanded, so that after the particles are inertially separated on the expansion side, they rebound on the flush side and can still smoothly enter the next separation, maintaining the existing movement order. By staggering the expansion channels and contraction channels and the coordinated use of electrodes, the length of the entire channel is shortened, the structure of the channel is simplified, and at the same time, the effect of high flux and good separation can still be achieved.

[0022] (2) Setting up multiple parallel and spaced electrodes is beneficial to accelerating the separation of particles in the liquid.

[0023] (3) The chip body includes an upper cover plate and a lower cover plate. The upper cover plate is made of polydimethylsiloxane, which has good light transmittance and biocompatibility, is easy to bond to glass, and has low cost. The lower cover plate is made of indium tin oxide conductive glass, which has good biocompatibility and does not affect the activity of biological cells in the liquid. At the same time, it has good conductivity and high light transmittance.

[0024] (4) The lower cover has good electrical conductivity. By fixing the electrode on the lower cover, the electrode can be energized by an external power source through the lower cover.

[0025] (5) The axis of the inlet channel is parallel to the axis of the expansion channel, so that the particles in the liquid still show a relatively regular and well-distributed pattern when flowing into the expansion channel under the action of inertia. The width of the contraction channel, inlet channel, and outlet channel is consistent, which helps to control the flow direction of the particles.

[0026] (6) The electrode tilt angle is controlled within the range of 70 degrees and 80 degrees, which not only extends the electrode length within a limited space, but also helps to enhance the effect of dielectrophoresis on the particles.

[0027] (7) If expansion channels and contraction channels are added, the number of electrodes can be reduced, or the channel length can be further shortened and the number of electrodes increased. When the number of electrodes is set in the range of 8 to 12, the particle separation can be accelerated while ensuring the presentation of the separation state. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 FIG. 1 is a schematic diagram of a top view of a channel provided in one embodiment of the present disclosure;

[0029] Figure 2 Shown is a perspective schematic diagram of the three-dimensional structure of a chip body provided by an embodiment of the present disclosure.

[0030] In the figure: 1. Inlet channel; 2. Outlet channel; 3. Expansion channel; 4. Contraction channel; 5. Electrode; 6. Upper cover; 7. Lower cover. DETAILED DESCRIPTION

[0031] To make the purposes, features, and advantages of the present disclosure more apparent and understandable, the technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of the present disclosure without creative work shall fall within the scope of protection of the present disclosure.

[0032] In order to facilitate the separation of particles in liquids, such as Figure 1 As shown, an embodiment of the present disclosure provides a microfluidic chip, including a chip body, the chip body is provided with channels running through both ends, the first end of the channel is an inlet channel 1 for liquid input, and the second end of the channel is an outlet channel 2 for liquid output.

[0033] The expansion channel 3 and the contraction channel 4 are alternately arranged between the inlet channel 1 and the outlet channel 2. The channel width of the expansion channel 3 is greater than that of the inlet channel 1, the outlet channel 2 and the contraction channel 4.

[0034] Taking the axis of the inlet channel 1 as a reference, one side of the expansion channel 3 and the contraction channel 4 are both arranged flush with the inlet channel 1 on one side of the axis, and the other sides of the expansion channel 3 and the contraction channel 4 are arranged to expand toward the other side of the axis;

[0035] An electrode 5 is provided in the expansion channel 3 .

[0036] Among them, liquid can be input into the inlet channel 1 through an external microfluidic pump, so the liquid has a certain initial flow rate, and after passing through the inlet channel 1, it flows into the expansion channel 3 under the action of inertia. The channel width of the expansion channel 3 is large, and the particles in the liquid are subject to different inertia due to their different sizes. Since the expansion channel 3 and the contraction channel 4 are arranged in sequence, the particles are constantly opening and closing in the flow of the liquid, showing expansion impact and contraction flow, further aggravating the inertial separation between particles of different sizes, until they are constrained by the last contraction channel 4 and the outlet channel 2, so that particles of different sizes in the liquid are in a separated distribution state when flowing out. It should be understood that the different sizes of particles refer to particles that are not in the same order of magnitude, that is, there is a certain range, and the particles within the range belong to the same type, and the particles within the range are not required to be exactly the same.

[0037] Electrodes 5 are provided within the expansion channel 3 to form an overall non-uniform electric field within the channel. Particles entering from the inlet channel 1 with an initial velocity are subject to different forces within the non-uniform electric field. Therefore, when the particles flow within the channel, in addition to being affected by inertia, they are also affected by the electric field, namely dielectrophoresis (dielectrophoresis refers to the displacement phenomenon caused by the polarization effect of dielectric particles in a non-uniform electric field). By providing electrodes that can be energized to form a non-uniform electric field, particles of different sizes are subject to different forces from inertia and dielectrophoresis, which can accelerate the separation process of different particles and produce different motion trajectories. Therefore, it should be understood that by providing an electric field to accelerate particle separation, the overall length of the channel can be shortened accordingly, such as by reducing the number of expansion channels 3 and contraction channels 4, thereby reducing production costs.

[0038] Both the expansion channel 3 and the contraction channel 4 expand toward one side of the axis, while the other side is flush with the inlet channel 1. After entering the inlet channel 1, the inertia of different particles takes on different directions. For example, one type of particles may flow in a larger arc, located on the side of the expansion channel 3, while another type of particles may flow in a smaller arc, located on the side flush with the expansion channel 3. This results in a state where each type of particle is distributed and flows according to a certain pattern. When these particles enter the next expansion channel 3, this state is not disrupted, resulting in a remixed state.

[0039] Based on the above scheme, the present disclosure provides a microfluidic chip, in which the liquid enters the inlet channel 1 at an initial velocity and then enters the expansion channel 3 with the widest channel width under the action of inertia, and the expansion channel 3 further promotes the separation of the movement paths of particles of different sizes in the liquid; an electrode 5 is arranged in the expansion channel 3 to form a non-uniform electric field, so that the particles are subjected to the force of dielectrophoresis in addition to inertia, which can accelerate the separation of particles of different sizes; at the same time, the inlet channel 1 is directly connected to the expansion channel 3, and the channel width of the expansion channel 3 is the widest, and one side of the expansion channel 3 and the contraction channel 4 is arranged flush with the inlet channel 1, and only expanded on the other side, so that after the particles are inertially separated on the expanded side, they rebound on the flush side and can still smoothly enter the next separation, maintaining the existing movement order. By using the staggered expansion channels 3 and contraction channels 4 and the electrodes 5, the length of the entire channel is shortened, the structure of the channel is simplified, and at the same time, the effects of high flux and good separation can still be achieved.

[0040] Preferably, a plurality of electrodes 5 are provided, and each electrode 5 is arranged in parallel and at intervals, and the intervals between each electrode 5 are arranged at equal intervals.

[0041] Because the electrodes 5 form an electric field when energized, this field accelerates the particle separation process. Accordingly, the greater the number of electrodes 5, the greater the interference of the electric field. Within a certain range of electrodes 5, the effect is also better. The regular arrangement of the electrodes 5 also creates a certain regularity in the dielectrophoresis range experienced by the particles in the electric field area.

[0042] Preferably, Figure 2 As shown, the chip body is composed of an upper cover plate 6 and a lower cover plate 7, which are covered together to form a channel; the material of the upper cover plate 6 is polydimethylsiloxane, and the material of the lower cover plate 7 is indium tin oxide conductive glass.

[0043] Among them, the material of the upper cover plate 6 is PDMS (Polydimethylsiloxane), which has good light transmittance and biocompatibility, is easy to bond with glass, and has low cost; the material of the lower cover plate 7 is ITO (Indium Tin Oxide) indium tin oxide conductive glass, which has good biocompatibility and does not affect the activity of biological cells in the liquid. At the same time, it has good conductivity and high light transmittance.

[0044] The covering method herein includes bonding. Bonding involves directly bonding two clean, atomically flat, homogeneous or heterogeneous semiconductor materials, which have been cleaned and activated, under certain conditions. The wafers are bonded together through van der Waals, molecular, or even atomic forces. Therefore, bonding ensures the channel's tightness. It should be understood that this is merely an example; the upper cover plate 6 and lower cover plate 7 can also be joined by gluing or other methods, as long as the sealing requirements are met. This is not a specific limitation.

[0045] Preferably, the electrode 5 is fixed on the lower cover plate 7 and extends from one side of the expansion channel 3 to the other side. The electrode 5 is connected to an external power source through the lower cover plate 7.

[0046] The lower cover plate 7 can be larger than the upper cover plate 6. The electrode 5 is fixed to the lower cover plate 7, and the channel structure is opened in the upper cover plate 6. The upper cover plate 6 and the lower cover plate 7 are overlapped as required, and the electrode 5 is positioned within the expansion channel 3. When the electrode 5 is fixed to the lower cover plate 7, due to the good electrical conductivity of the lower cover plate 7, it is only necessary to apply power to both sides of the lower cover plate 7 through an electrical device to energize both ends of the electrode 5 to form an electric field. It should be understood that the applied voltage can be varied, and therefore the strength of the electric field formed by the electrode 5 can be adjusted. The specific adjustment should be based on the actual application and is not limited here.

[0047] Preferably, the axis of the inlet channel 1 and the axis of the expansion channel 3 are arranged parallel to each other.

[0048] Among them, the inlet channel 1 can be set as a rectangular channel. Similarly, the contraction channel 4 can also be set as a rectangular channel. The structure has a regular shape, which makes the particles more regular when flowing. At the same time, it is easier to make and the cost is lower.

[0049] Preferably, the channel widths of the contraction channel 4 , the inlet channel 1 and the outlet channel 2 are the same.

[0050] It should be understood that the channel widths of the contraction channel 4, the inlet channel 1, and the outlet channel 2 can be the same or different, as long as they are smaller than the expansion channel 3. When the channel widths of the contraction channel 4, the inlet channel 1, and the outlet channel 2 are all set to the same, it is easier to control the separation of particles, avoid negative effects caused by an overly complex structure, such as disrupting the inertial paths of different types of particles and causing remixing, and also reduce the manufacturing difficulty.

[0051] Preferably, the electrode 5 is an inclined straight line, and with the axis of the expansion channel 3 as a reference, the acute angle between the electrode 5 and the axis of the expansion channel 3 is in the range of 70 degrees to 80 degrees.

[0052] The electrode 5 is tilted relative to the axis of the expansion channel 3, so that the direction of the electric field force is different. Within this angle range, the electric field formed by the electrode 5 has a better effect of promoting inertial separation of particles.

[0053] Preferably, the number of electrodes 5 in the expansion channel 3 is negatively correlated with the number of expansion channels 3 .

[0054] The more expansion channels 3 are set, the more contraction channels 4 are set, and the overall length of the channel becomes longer. Therefore, in order to shorten the overall length of the channel, the number of electrodes 5 can be increased to compensate.

[0055] Preferably, there are 8-12 electrodes 5 in each expansion channel 3 .

[0056] The number of electrodes 5 also determines the interference intensity of the electric field on the particles. If there are too many electrodes 5, the particles will reach a better separation state before reaching the outlet for observation, while the expected separation state should be presented after flowing out of the outlet channel. Similarly, a longer channel length (such as by increasing the number of expansion channels 3 and contraction channels 4) is also not expected. Therefore, the number of electrodes 5 set and the number of expansion channels 3 set should be set within a more reasonable range based on actual conditions.

[0057] According to the above structure, the present disclosure provides a microfluidic chip with specific values ​​set, including:

[0058] Four expansion channels 3 and four contraction channels 4 are arranged alternately. Ten electrodes 5 are provided in each expansion channel 3. The electrodes 5 are arranged parallel to each other, with the acute angle between the electrodes 5 and the axis of the expansion channel 3 being 75 degrees. The spacing between the electrodes 5 is 5 μm (micrometers).

[0059] The channel widths of the inlet channel 1, the contraction channel 4 and the outlet channel 2 are all 50 μm, wherein the channel width of the expansion channel 3 is 350 μm, the lengths of the inlet channel 1, the contraction channel 4 and the outlet channel 2 are all 300 μm, and the length of the entire channel is 2700 μm.

[0060] Therefore, the microfluidic chip provided by the present disclosure has a simple structure, short channel length, and low cost. When used in conjunction with the non-uniform electric field formed by the electrode 5, the particles can achieve better separation of different types of particles under the combined force of dielectrophoresis and inertia, thereby ensuring good efficiency while also ensuring flux.

[0061] The microfluidic chip provided by the present disclosure can be used in conjunction with existing bedside blood purification devices, and can also be used to filter out pathogens (bacteria or fungi, etc.) in blood infections such as sepsis, septicemia, and bacteremia, and re-infuse the plasma from which the pathogens have been filtered out to achieve a purification effect.

[0062] According to the above structure, the present disclosure also provides a specific implementation method as follows:

[0063] The lower cover plate 7 is energized by an electrical device, so that the electrode 5 forms a non-uniform electric field in the channel. The liquid is injected into the inlet channel 1 by a microfluidic pump. The inlet flow rate of the liquid is 20 ml / min (milliliters per minute). After passing through the inlet channel 1, the liquid continues to flow under the action of inertia and enters the expansion channel 3. Under the influence of inertia and dielectrophoresis, particles of different sizes in the liquid gradually separate and form trajectories under the action of their respective inertia. Through continuous expansion and contraction, when the liquid flows out of the outlet channel 2, the flow trajectories of different particle distributions are different, and different particles are discharged through different liquid reservoirs connected to the outlet channel 2.

[0064] It should be understood that the injected liquid can be one liquid or two liquids, as long as the injected liquid contains particles of more than one size and meets the separation requirement. The liquid is not specifically limited here.

[0065] According to the technical effects that the present disclosure aims to achieve, the chip body needs to meet the following conditions, such as good light transmittance for easy observation, good biocompatibility to avoid affecting the activity of biological cells, easy processing, good sealability, good heat dissipation and suitable electrical properties. Therefore, ITO conductive glass with good conductivity, high light transmittance, low cost and easy processing is selected as the material for making electrodes (including the lower cover), and PDMS with good chemical inertness and easy demolding is used as the material for making the upper cover.

[0066] In one example, the present disclosure provides a manufacturing process for an upper cover plate, a lower cover plate, and a bonding process for the upper cover plate and the lower cover plate, as follows:

[0067] Regarding the production of the lower cover plate, existing processing techniques mainly include spray coating (using techniques such as thermal evaporation or vacuum sputtering to deposit a layer of metal electrodes on a substrate), photolithography (spin-coating photoresist on a metal film surface, leaving a microelectrode structure after exposure and etching), and electroless plating (reducing metal ions in a solution on the surface of an activated substrate to produce metal electrodes on the substrate surface). The present disclosure uses photolithography to process the lower cover plate (focusing on the production of electrodes fixed to the lower cover plate). The main steps are cleaning, coating, pre-baking, exposure, development, post-baking, etching, and stripping.

[0068] Step 101, cleaning; after peeling off the plastic film on the surface of the ITO conductive glass, place it in an acetone solution and an alcohol solution for ultrasonic cleaning for 10 minutes, then use clean water for ultrasonic cleaning for 10 minutes, rinse it clean, blow it dry with nitrogen and set aside.

[0069] Step 102, coating the ITO conductive glass with a 2 μm thick positive photoresist by using a coating machine at a low speed of 500 r / min (revolutions per minute) for 10 seconds and a high speed of 2500 r / min for 30 seconds, and remove the excess positive photoresist behind the ITO conductive glass with alcohol.

[0070] Step 103, pre-baking; place the ITO conductive glass with the positive photoresist on a baking table at a temperature of 100°C (degrees Celsius) for 60 seconds to dry the photoresist.

[0071] Step 104, exposure: Use a photolithography machine to photoetch the electrode pattern on the mask onto the ITO conductive glass surface. The electrode pattern on the mask is a light-proof area that has not been exposed to ultraviolet light and can be retained after development.

[0072] Step 105, Development: Place the photolithographically finished ITO conductive glass in a developer for 30 seconds. This washes away the UV-exposed areas, leaving only the unexposed electrode structure. Rinse thoroughly with deionized water and dry with nitrogen.

[0073] Step 106, post-baking; place the dried ITO conductive glass on a baking table and heat for 2 minutes to harden the film. The baking table has been preheated to 100°C.

[0074] Step 107: Etching: Heat a pre-prepared etching solution (concentrated hydrochloric acid: concentrated nitric acid: deionized water = 50:3:50) to 55°C. Place the developed ITO conductive glass in the etching solution for 45 seconds to allow the etching solution to completely etch the metal in areas not covered by the positive photoresist. Due to the high temperature of the etching solution, the etching rate is rapid, so controlling the etching time is crucial. After removing the ITO conductive glass from the etching solution, rinse it with deionized water and blow dry it with nitrogen. Use a multimeter to measure the surface of the ITO conductive glass for any metal residue. If any metal residue is present, repeat the etching steps until no residue is detected. Then, place the ITO conductive glass under a microscope to observe the integrity of the electrode structure.

[0075] Step 108, stripping; immerse the corroded ITO conductive glass in a stripping solution for 8 to 10 minutes to remove the remaining photoresist positive resist on the surface of the ITO conductive glass, rinse with deionized water and blow dry with nitrogen.

[0076] At this point, the production of the lower cover is completed. During the production process, the electrodes have been fixed on the lower cover.

[0077] In the present disclosure, the structure of the channel is mainly obtained by processing the upper cover plate, and the processing of the upper cover plate adopts a molding method, and the main steps are cleaning, coating, pre-baking, exposure, post-baking, development, pouring and curing, and peeling.

[0078] Step 201, cleaning; placing the silicon wafer in a mixed solution of H2SO4 (sulfuric acid) and H2O2 (hydrogen peroxide) for ultrasonic cleaning for 10 minutes, then ultrasonic cleaning with deionized water for 10 minutes, and drying with nitrogen for later use.

[0079] Step 202 , coating the negative photoresist on the surface of the silicon wafer at a low speed of 500 r / min and a high speed of 3000 r / min, with a thickness of about 50 μm.

[0080] Step 203, pre-baking: Place the coated silicon wafer on a preheated baking table at 65°C for 3 minutes. Then, increase the temperature by 5°C every 5 minutes until the baking table reaches 95°C. Continue heating for 10 minutes. Allow the negative photoresist on the wafer to cool naturally to room temperature (to prevent wrinkles on the negative photoresist surface caused by a sudden drop in temperature) and set aside.

[0081] Step 204, exposure: Place the mask in the photolithography machine, align the silicon wafer with the mask, and photolithography the channel structure onto the wafer surface. Underdosing the photolithography metering results in unclear surface structures and rough edges. Overdosing the photolithography metering can easily cause surface structure loss. Therefore, careful attention must be paid to the choice of photolithography metering.

[0082] Step 205, post-baking: Preheat the baking table to 65°C, heat the photolithographic silicon wafer for 2 minutes, then increase the temperature by 5°C every 5 minutes until it reaches 95°C. Heat at the current temperature for 15 minutes, then naturally cool to room temperature. Because sudden temperature increases or decreases can cause wrinkles or cracks on the negative photoresist surface, a slow ramp up and ramp down is required.

[0083] Step 206, Development: Place the post-baked silicon wafer in SU8 developer for 5 minutes to remove the areas not exposed to UV light, leaving the channel structure. After development, rinse with deionized water and dry with nitrogen.

[0084] Step 207, casting and curing: PDMS prepolymer and curing agent are thoroughly mixed in a ratio of 10:1. The mixture is allowed to stand for 30 minutes before being cast onto the silicon wafer with the channel structure. The mixture is then placed in a vacuum drying oven and evacuated for 30 minutes to remove air bubbles. The mixture is then heated in a drying oven at 95°C for 1 hour to fully cure.

[0085] Step 208, peeling; peeling the cured PDMS from the surface of the silicon wafer, removing the excess portion with a knife, and using a puncher to punch holes at the inlet and outlet of the channel structure to communicate with the interior of the channel.

[0086] At this point, the production of the upper cover is completed.

[0087] After the upper and lower cover plates are fabricated, they need to be bonded together. Existing bonding techniques include anodic bonding, direct bonding, adhesive bonding, oxygen plasma bonding, and low-temperature bonding. Due to the strong adhesion between PDMS and glass, this disclosure utilizes oxygen plasma bonding.

[0088] Step 301: Oxygen plasma treatment: Place the ITO conductive glass with the electrode structure and the PDMS with the channel, facing upward, into an oxygen plasma bonding machine. Close the chamber door and evacuate the chamber until it is in a vacuum state. A small amount of oxygen is introduced, and the energizer is turned on to emit purple light. Treat the ITO conductive glass and PDMS surfaces for 30 seconds before removing them for later use.

[0089] Step 302, alignment: roughly align the position of the channel and the position of the electrode under a microscope (such as placing the electrode in the expansion channel), and fine-tune until they are completely aligned, press to initially bond the PDMS and ITO conductive glass together to obtain the chip body.

[0090] Step 303, heating; placing the chip body in an oven preheated to 75°C and heating for 10 minutes to firmly bond the ITO conductive glass and PDMS together, and using deionized water to pass through the channel to check the sealing performance.

[0091] Step 304: Connect the wires and the catheter. Use conductive tape to secure the wires to the lower cover plates on both sides of the electrode. Connect the wires on both sides to the two ends of the power device. Insert the catheter of the microfluidic pump into the inlet channel to introduce liquid and into the outlet channel to connect to different liquid reservoirs.

[0092] At this point, the bonding between the upper cover plate (PDMS) and the lower cover plate (ITO conductive glass) is completed.

[0093] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0094] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

[0095] It should also be noted that in the apparatus, device, and method of the present application, each component or each step can be decomposed and / or recombined, and such decomposition and / or recombination should be regarded as equivalent solutions of the present application.

[0096] The above description of the disclosed aspects is provided to enable any person skilled in the art to make or use the present application. Various modifications to these aspects will be readily apparent to those skilled in the art, and the general principles defined herein may be applied to other aspects without departing from the scope of the present application. Therefore, the present application is not intended to be limited to the aspects shown herein, but rather to be accorded the widest scope consistent with the principles and novel features disclosed herein.

[0097] The above description has been provided for the purpose of illustration and description. Furthermore, this description is not intended to limit the embodiments of the present application to the forms disclosed herein. Although a number of example aspects and embodiments have been discussed above, those skilled in the art will recognize certain variations, modifications, alterations, additions, and sub-combinations thereof.

Claims

1. A microfluidic chip, comprising a chip body, wherein the chip body is provided with channels running through both ends, wherein the first end of the channel is an inlet channel (1) for liquid input, and the second end of the channel is an outlet channel (2) for liquid output, wherein: An expansion channel (3) and a contraction channel (4) are arranged alternately between the inlet channel (1) and the outlet channel (2), and the channel width of the expansion channel (3) is greater than that of the inlet channel (1), the outlet channel (2) and the contraction channel (4); Taking the axis of the inlet channel (1) as a reference, one side of the expansion channel (3) and the contraction channel (4) are both arranged flush with the inlet channel (1) on one side of the axis, and the other sides of the expansion channel (3) and the contraction channel (4) are arranged to expand toward the other side of the axis; An electrode (5) is provided in the expansion channel (3); A plurality of electrodes (5) are provided, each of the electrodes is arranged in parallel and at intervals, and the number of the electrodes (5) in the expansion channel (3) is negatively correlated with the number of the expansion channels (3).

2. The microfluidic chip according to claim 1, characterized in that The chip body is composed of an upper cover plate (6) and a lower cover plate (7), and the upper cover plate (6) and the lower cover plate (7) are arranged to cover each other to form the channel; The material of the upper cover plate (6) is polydimethylsiloxane, and the material of the lower cover plate (7) is indium tin oxide conductive glass.

3. The microfluidic chip according to claim 2, characterized in that: The electrode (5) is fixed on the lower cover plate (7), extending from one side of the expansion channel (3) to the other side, and the electrode (5) is connected to an external power source through the lower cover plate (7).

4. The microfluidic chip according to claim 1, characterized in that The axis of the inlet channel (1) and the axis of the expansion channel (3) are arranged parallel to each other.

5. The microfluidic chip according to claim 1, characterized in that The channel widths of the contraction channel (4), the inlet channel (1) and the outlet channel (2) are the same.

6. The microfluidic chip according to claim 1, characterized in that The electrode (5) is a straight line arranged at an angle, and with the axis of the expansion channel (3) as a reference, the acute angle between the electrode (5) and the axis of the expansion channel (3) ranges from 70 degrees to 80 degrees.

7. The microfluidic chip according to any one of claims 1 to 6, characterized in that: There are 8 to 12 electrodes (5) in each expansion channel (3).

8. The microfluidic chip according to claim 7, characterized in that: The electrodes (5) in each expansion channel (3) are arranged at equal intervals.

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