A digital microfluidic chip with replaceable hydrophobic dielectric membrane and a processing method thereof

Abstract

The application relates to a digital microfluidic chip with replaceable hydrophobic dielectric film and a processing method thereof, which comprises a lower plate and an upper plate, and the lower plate and the upper plate are connected through conductive adhesive tape; the lower plate is composed of a multilayer structure and sequentially comprises an FPC substrate, an electrode layer, a first PDMS adhesive layer, a PI dielectric film and a first hydrophobic layer from bottom to top, wherein the PI dielectric film and the first hydrophobic layer constitute a replaceable hydrophobic dielectric film, and the upper plate sequentially comprises a second hydrophobic layer, an ITO-PET film, a second PDMS adhesive layer and a glass substrate from bottom to top. In the chip processing method disclosed by the application, the replaceable customized hydrophobic dielectric film can realize the customized control of the operation area on the chip, and greatly reduces the cost of directly replacing the whole chip after use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of digital microfluidics, and in particular provides a digital microfluidic chip with replaceable hydrophobic dielectric film and a processing method thereof. BACKGROUND

[0002] As an important technology in the field of microfluidics, digital microfluidics realizes programmed and precise manipulation of discrete microdroplets through dielectric wetting effect, and has been widely applied in the fields of biological analysis, drug screening, chemical synthesis, etc. However, in practical application, the inevitable biological sample residue and high chip processing cost are still the main bottlenecks restricting the development of this technology.

[0003] On the one hand, due to the diversity and complexity of biological samples, biological samples often remain on the surface of the chip during the use of the digital microfluidic chip, which not only affects the reusability of the chip, but also may interfere with the subsequent detection results. On the other hand, in order to solve this problem, the entire chip usually needs to be cleaned or replaced, resulting in high processing cost of the digital microfluidic chip, which is difficult to realize mass production. SUMMARY

[0004] In view of the above technical problems, a digital microfluidic chip with replaceable hydrophobic dielectric film and a processing method thereof are provided to overcome the influence of sample adhesion on the reusability of the chip during the use of the digital microfluidic chip at the present stage, and effectively reduce the cost of the chip.

[0005] The technical means adopted by the present application are as follows:

[0006] The digital microfluidic chip with replaceable hydrophobic dielectric film comprises a lower plate and an upper plate, and the upper and lower plates are connected by a conductive adhesive tape. The lower plate is composed of a multi-layer structure, which comprises an FPC substrate, an electrode layer, a first PDMS adhesion layer, a PI dielectric film and a first hydrophobic layer from bottom to top. The PI dielectric film and the first hydrophobic layer constitute a replaceable hydrophobic dielectric film. The upper plate comprises a second hydrophobic layer, an ITO-PET film, a second PDMS adhesion layer and a glass substrate from bottom to top.

[0007] Further, the electrode layer is processed on the FPC substrate according to the functional requirements by using a microelectronic processing technology.

[0008] Further, the second PDMS adhesion layer and the first PDMS adhesion layer are respectively processed on the surface of the FPC substrate of the lower plate and the glass substrate of the upper plate by a spin coating method.

[0009] After hydrophobic layers are constructed on the surfaces of the PI dielectric film and the ITO-PET film, the films are respectively adhered to the first PDMS adhesive layer and the second PDMS adhesive layer.

[0010] Furthermore, the PDMS adhesion layer is processed by a spin coating and curing method, and the thickness of the PDMS adhesion layer is 3 to 4 μm.

[0011] Furthermore, the hydrophobic layer is a Pyflon T8 hydrophobic coating with a solid content of 1%, which is processed on the PI dielectric film and ITO-PET film by spin coating or ultrasonic spraying. The thickness of the PI dielectric film is 3 to 5 μm, and the thickness of the hydrophobic layer is 200 to 400 nm.

[0012] Furthermore, the thickness of the conductive tape is 150 to 300 μm.

[0013] The present invention also discloses a method for preparing the digital microfluidic chip capable of quickly replacing a hydrophobic dielectric film, comprising the following steps:

[0014] On the FPC substrate with the electrode layer, the non-droplet manipulation area is covered with insulating tape for isolation, and PDMS is spin-coated on the surface of the FPC substrate. The PDMS is then heated to solidify, and the insulating tape is then removed to complete the processing of the PDMS adhesion layer.

[0015] The PI dielectric film and the ITO-PET film were attached to the surfaces of separate glass sheets respectively; a Pyflon T8 solution with a solid content of 1% was spin-coated on the surfaces of the PI dielectric film and the ITO-PET film respectively; and then heated to complete the processing of the hydrophobic layer.

[0016] Furthermore, the processing of the PDMS adhesion layer specifically includes the following steps:

[0017] S11. Soak the FPC substrate in anhydrous ethanol to clean it;

[0018] S12. PDMS and curing agent were weighed in a ratio of 10:1 to prepare the PDMS system, stirred thoroughly, and then placed in a vacuum tank and evacuated until there were no bubbles.

[0019] S13. The non-droplet manipulation area of ​​the FPC substrate is covered with insulating tape and then placed in a plasma cleaner to activate its surface;

[0020] S14. The degassed PDMS was poured onto the surface of the activated area of ​​the FPC substrate / the surface of the upper plate glass substrate and spin-coated in two steps; the first step was accelerated from 100 r / s to 500 rpm and then spun at this speed for 10 seconds; the second step was accelerated from 300 r / s to 6000 rpm and then spun at this speed for 60 seconds;

[0021] S15. Place the spin-coated PDMS lower plate FPC substrate and the upper plate glass substrate on a hot plate and heat them at 80-85°C until the PDMS thin layer solidifies and forms a permanent bond with the surface of the activated area.

[0022] Furthermore, the processing of the hydrophobic layer specifically includes the following steps:

[0023] S21. Cut the PI dielectric film and ITO-PET film into specified sizes according to usage requirements;

[0024] S22. Take a clean glass sheet of appropriate size, spray a certain amount of ethanol on the surface of the glass sheet with a spray bottle, then blow it dry with nitrogen. Attach the PI dielectric film and ITO-PET film to the surface of the glass sheet, then wipe the PI dielectric film and ITO-PET film with alcohol cotton to remove any impurities and wipe the film surface dry with dust-free paper;

[0025] S23. Using a pipette, a 1-6% Pyflon T8 solution was applied to the surface of the PI dielectric film and spin-coated in two steps: the first step was accelerating from 100 r / s to 500 rpm and then spinning at this speed for 20 seconds; the second step was accelerating from 300 r / s to 1500 rpm and then spinning at this speed for 60 seconds;

[0026] S24. Place the spin-coated glass sheet with the PI dielectric film on a heating plate and heat it to allow the solvent in the Pyflon coating to evaporate completely. The heating is carried out in two steps: the first step is heating at 60-80°C for 10 minutes, and the second step is heating at 150°C for 30 minutes. The glass sheet with the ITO-PET film also needs to be heated, and the heating parameters are heating at 70-80°C for 1 hour.

[0027] Furthermore, the hydrophobic layer can be formed by ultrasonic spraying, which includes the following steps:

[0028] S1. Prepare two 150mm*150mm glass plates and three 50mm*50mm glass plates for standby use. Wipe the glass surfaces with anhydrous ethanol to remove impurities. Cut A4-sized sheets with a thickness of 3 to 5μm and PI films into 150mm*150mm sizes, and cut ITO-PET films into 5mm*5mm sizes.

[0029] S2. Spray a certain amount of anhydrous ethanol on the surface of a clean glass slide and carefully transfer the two films to the corresponding glass slide surfaces using tweezers.

[0030] S3. The glass sheet with two films was placed on the spraying bottom plate of the ultrasonic sprayer; the ultrasonic atomizing spraying equipment was started, with a 1% solid content of Pyflon T8 solution as a slurry, at a carrier gas pressure of 0.02 to 0.04 MPa, at a discharge rate of 0.3 ml / min, sprayed in a cross-spraying manner, sprayed 4 to 5 times;

[0031] S4. Then, the heating plate of the sprayer is started to heat the glass sheet at 150° C. to 160° C. for 1 hour to evaporate the solvent to obtain a PI dielectric film and an ITO-PET dielectric film containing a hydrophobic layer.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1) The present invention uses an FPC substrate for chip electrode processing, which significantly reduces chip cost while ensuring electrode flatness. PI dielectric film is used as the dielectric layer, and the dielectric layer has excellent stability.

[0034] 2) In the chip processing method disclosed in the present invention, the concept of single-throw type is proposed, which can solve the inevitable impact of biological sample adhesion on chip repeatability in the current field of digital microfluidics technology.

[0035] 3) In the chip processing method disclosed in the present invention, the quickly replaceable customized hydrophobic dielectric layer film can achieve customized control of the operating area on the chip, while greatly reducing the cost of directly replacing the entire chip after use. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative labor.

[0037] Figure 1 This is a schematic diagram of the structure of a digital microfluidic chip with a quickly replaceable customized hydrophobic dielectric film according to the present invention.

[0038] Figure 2 It is a side view of the structure of the present invention.

[0039] Figure 3 Flowchart of the processing of the PDMS adhesion layer on the chip substrate layer in the present invention.

[0040] Figure 4 This is a graph showing the test results of the PDMS adhesion layer processing thickness in the present invention.

[0041] Figure 5FIG. 4 is a process flow chart of the hydrophobic dielectric layer in the present invention.

[0042] Figure 6 Schematic diagram showing the comparison of contact angles of the PI dielectric film before and after hydrophobic treatment in the present invention.

[0043] Figure 7 2 is a comparison chart of the processing effects of two hydrophobic layer processing methods in an embodiment of the present invention.

[0044] Figure 8 Graphs showing the results of four basic droplet manipulation operations on a digital microfluidic chip with a rapidly replaceable customizable hydrophobic dielectric film according to the present invention.

[0045] In the figure: 1. Lower electrode; 2. Hydrophobic dielectric film; 3. Upper electrode; 4. FPC substrate; 5. Electrode layer; 6. PDMS adhesion layer; 7. PI dielectric film; 8. Hydrophobic layer; 9. Conductive tape; 10. Glass sheet; 11. Anhydrous ethanol; 12. Insulating tape; 13. Plasma cleaning machine; 14. ITO-PET film. DETAILED DESCRIPTION

[0046] It should be noted that, in the absence of conflict, the embodiments and features of the embodiments of the present invention can be combined with each other. The present invention will be described in detail below with reference to the accompanying drawings and in combination with the embodiments.

[0047] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0048] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present invention. As used herein, unless the context clearly indicates otherwise, the singular form is intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, they indicate the presence of features, steps, operations, devices, components and / or combinations thereof.

[0049] Unless otherwise specifically stated, the relative arrangement of the parts and steps, numerical expressions and numerical values ​​set forth in these embodiments do not limit the scope of the present invention. At the same time, it should be clear that, for ease of description, the sizes of the various parts shown in the drawings are not drawn according to the actual proportional relationship. The technology, methods and equipment known to those of ordinary skill in the relevant art may not be discussed in detail, but in appropriate cases, the technology, methods and equipment should be considered as part of the specification. In all examples shown and discussed here, any specific value should be interpreted as being merely exemplary, not as a limitation. Therefore, other examples of the exemplary embodiments may have different values. It should be noted that similar numbers and letters represent similar items in the following figures, and therefore, once an item is defined in one figure, it does not need to be further discussed in subsequent figures.

[0050] In the description of the present invention, it should be understood that the directions or positional relationships indicated by directional words such as "front, back, up, down, left, right", "horizontal, vertical, vertical, horizontal" and "top, bottom" are usually based on the directions or positional relationships shown in the accompanying drawings. They are only for the convenience of describing the present invention and simplifying the description. Unless otherwise specified, these directional words do not indicate or imply that the device or element referred to must have a specific direction or be constructed and operated in a specific direction. Therefore, they cannot be understood as limiting the scope of protection of the present invention: the directional words "inside and outside" refer to the inside and outside relative to the outline of each component itself.

[0051] For ease of description, spatially relative terms such as "above", "above", "on the upper surface of", "above", etc. may be used herein to describe the spatial positional relationship of a device or feature to other devices or features as shown in the figures. It should be understood that spatially relative terms are intended to include different orientations of the device in use or operation in addition to the orientation described in the figures. For example, if the device in the drawings is inverted, the device described as "above other devices or structures" or "above other devices or structures" will be positioned as "below other devices or structures" or "below their position devices or structures". Thus, the exemplary term "above" can include both "above" and "below". The device can also be positioned in other different ways (rotated 90 degrees or in other orientations), and the spatially relative descriptions used here are interpreted accordingly.

[0052] In addition, it should be noted that the use of terms such as "first" and "second" to limit components is only for the convenience of distinguishing the corresponding components. Unless otherwise stated, the above terms have no special meaning and therefore cannot be understood as limiting the scope of protection of the present invention.

[0053] like Figure 1 、 Figure 2 As shown, the embodiment of the present invention discloses a digital microfluidic chip with a rapidly replaceable hydrophobic dielectric film, comprising a lower plate 1 and an upper plate 3, the upper and lower plates being connected by a conductive tape 9; the lower plate is composed of a multi-layer structure, which includes, from bottom to top, an FPC substrate 4 (i.e. Figure 2 The base layer in the electrode layer 5, the first PDMS adhesion layer (ie Figure 2 The lower adhesive layer in the middle), the PI dielectric film 7 (ie Figure 2 PI dielectric layer in) and the first hydrophobic layer (i.e. Figure 2 The PI dielectric film and the first hydrophobic layer constitute a replaceable hydrophobic dielectric film 2, and the upper plate includes the second hydrophobic layer (i.e. Figure 2 The hydrophobic layer above the ITO-PET film 14, the second PDMS adhesion layer (ie Figure 2 the adhesive layer above the substrate) and the glass substrate.

[0054] Furthermore, the electrode layer is processed on the FPC substrate using a microelectronics processing technique according to functional requirements.

[0055] Furthermore, the second PDMS adhesion layer and the first PDMS adhesion layer are respectively processed on the FPC substrate surface of the lower electrode plate and the glass substrate of the upper electrode plate by a spin coating method;

[0056] After hydrophobic layers are constructed on the surfaces of the PI dielectric film and the ITO-PET film, the films are respectively adhered to the first PDMS adhesive layer and the second PDMS adhesive layer.

[0057] Furthermore, the PDMS adhesion layer 6 is processed by a spin coating and curing method, and the thickness of the PDMS adhesion layer is 3-4 μm.

[0058] Furthermore, the hydrophobic layer 8 is a Pyflon T8 hydrophobic coating with a solid content of 1%, which is processed on the PI dielectric film and ITO-PET film by spin coating or ultrasonic spraying. The thickness of the PI dielectric film is 3 to 5 μm, and the thickness of the hydrophobic layer is 200 to 400 nm.

[0059] Furthermore, the thickness of the conductive tape is 150 to 300 μm.

[0060] The present invention also discloses a method for preparing the digital microfluidic chip capable of quickly replacing a hydrophobic dielectric film, comprising the following steps:

[0061] On the FPC substrate with the electrode layer, the non-droplet manipulation area is covered with insulating tape 12 for isolation, and PDMS is spin-coated on the surface of the FPC substrate. The PDMS is then cured by heating, and the insulating tape is then removed and carefully peeled off along the target processing area to complete the processing of the PDMS adhesion layer.

[0062] The PI dielectric film and the ITO-PET film are respectively attached to the surface of a separate clean glass sheet 10; and a Pyflon T8 solution with a solid content of 1% is spin-coated on the surface of the PI dielectric film and the ITO-PET film respectively; and then heated to complete the processing of the hydrophobic layer.

[0063] Furthermore, if Figure 3 As shown, the processing of the PDMS adhesion layer specifically includes the following steps:

[0064] S11. The FPC substrate is placed in anhydrous ethanol 11 and soaked in clean water;

[0065] S12. PDMS and curing agent were weighed in a ratio of 10:1 to prepare the PDMS system, stirred thoroughly, and then placed in a vacuum tank and evacuated until there were no bubbles.

[0066] S13. The non-droplet manipulation area of ​​the FPC substrate is covered with insulating tape and then placed in a plasma cleaner 13 to activate its surface;

[0067] S14. The degassed PDMS was poured onto the surface of the activated area of ​​the FPC substrate / the surface of the upper plate glass substrate and spin-coated in two steps; the first step was accelerated from 100 r / s to 500 rpm and then spun at this speed for 10 seconds; the second step was accelerated from 300 r / s to 6000 rpm and then spun at this speed for 60 seconds;

[0068] S15. Place the spin-coated PDMS lower plate FPC substrate and the upper plate glass substrate on a hot plate and heat them at 80-85°C until the PDMS thin layer solidifies and forms a permanent bond with the surface of the activated area.

[0069] Furthermore, if Figure 5 As shown, the processing of the hydrophobic layer specifically includes the following steps:

[0070] S21. Cut the PI dielectric film and ITO-PET film into specified sizes according to usage requirements;

[0071] S22. Take a clean glass sheet of appropriate size, spray a certain amount of ethanol on the surface of the glass sheet with a spray bottle, then blow it dry with nitrogen. Attach the PI dielectric film and ITO-PET film to the surface of the glass sheet, then wipe the PI dielectric film and ITO-PET film with alcohol cotton to remove any impurities and wipe the film surface dry with dust-free paper;

[0072] S23. Using a pipette, a 1-6% Pyflon T8 solution was applied to the surface of the PI dielectric film and spin-coated in two steps: the first step was accelerating from 100 r / s to 500 rpm and then spinning at this speed for 20 seconds; the second step was accelerating from 300 r / s to 1500 rpm and then spinning at this speed for 60 seconds;

[0073] S24. Place the spin-coated glass sheet with the PI dielectric film on a heating plate and heat it to allow the solvent in the Pyflon coating to evaporate completely. The heating is carried out in two steps: the first step is heating at 60-80°C for 10 minutes, and the second step is heating at 150°C for 30 minutes. The glass sheet with the ITO-PET film also needs to be heated, and the heating parameters are heating at 70-80°C for 1 hour.

[0074] Furthermore, the hydrophobic layer can be formed by ultrasonic spraying, which includes the following steps:

[0075] S1. Prepare two 150mm*150mm glass plates and three 50mm*50mm glass plates for standby use. Wipe the glass surfaces with anhydrous ethanol to remove impurities. Cut A4-sized sheets with a thickness of 3 to 5μm and PI dielectric films into 150mm*150mm sizes, and cut ITO-PET films into 5mm*5mm sizes.

[0076] S2. Spray a certain amount of anhydrous ethanol on the surface of a clean glass slide and carefully transfer the two films to the corresponding glass slide surfaces using tweezers.

[0077] S3. The glass sheet with two films was placed on the spraying bottom plate of the ultrasonic sprayer; the ultrasonic atomizing spraying equipment was started, with a 1% solid content of Pyflon T8 solution as a slurry, at a carrier gas pressure of 0.02 to 0.04 MPa, at a discharge rate of 0.3 ml / min, sprayed in a cross-spraying manner, sprayed 4 to 5 times;

[0078] S4. Then, the heating plate of the sprayer is started to heat the glass sheet at 150° C. to 160° C. for 1 hour to evaporate the solvent to obtain a PI dielectric film and an ITO-PET dielectric film containing a hydrophobic layer.

[0079] The electrode shape pattern of the electrode layer is drawn by CAD software and processed on the FPC substrate layer by conventional microelectronics processing technology. To ensure smooth driving of the droplets, the area of ​​each driving electrode is about 0.04cm 2, the electrode spacing is maintained at 150μm. To ensure the feasibility of processing, the chip is designed to maintain a line width and line spacing of 60μm, and is finally processed on the FPC substrate layer through conventional microelectronics processing technology.

[0080] The sub-disposable hydrophobic dielectric layer and the hydrophobic electrode layer are formed on the PI dielectric film and the ITO-PET film by spin coating or ultrasonic spray coating, and then the sub-disposable hydrophobic dielectric layer and the hydrophobic electrode layer are tightly adhered to the PDMS adhesion layer under the action of van der Waals force.

[0081] The disposable hydrophobic dielectric layer and the ITO-PET hydrophobic electrode layer can be processed in batches and cut into specified shapes as needed to meet customization requirements. At the same time, the disposable hydrophobic dielectric layer can be directly replaced after each use, effectively solving the problem of biological sample residue on the digital microfluidic chip and reducing chip costs.

[0082] The conductive tape connecting the upper and lower plates of the digital microfluidic chip is made of woven fabric, which facilitates the assembly and disassembly of the chip and the replacement of the hydrophobic dielectric film.

[0083] According to functional requirements, the base plate of the FPC substrate can also be customized to process the heating circuit to achieve functions such as temperature control of droplets on the chip.

[0084] Example 1

[0085] This embodiment discloses a method for preparing the digital microfluidic chip capable of quickly replacing a hydrophobic dielectric film, comprising the following steps:

[0086] The non-droplet manipulation area on the FPC substrate is covered with insulating tape for isolation, and PDMS is spin-coated on the surface of the FPC substrate. The PDMS is then heated to solidify, and the insulating tape is then removed to complete the processing of the PDMS adhesion layer.

[0087] Attaching the PI dielectric film and the ITO-PET film to the surface of the glass sheet;

[0088] Spin-coat a 1% solid content Pyflon T8 solution on the surface of the PI dielectric film and the ITO-PET film, respectively; then heat to complete the hydrophobic layer processing;

[0089] Furthermore, the processing of the PDMS adhesion layer specifically includes the following steps:

[0090] S11. Soak the FPC substrate in anhydrous ethanol to clean it;

[0091] S12. PDMS and curing agent were weighed in a ratio of 10:1 to prepare the PDMS system, stirred thoroughly, and then placed in a vacuum tank and evacuated until there were no bubbles.

[0092] S13. The non-droplet manipulation area of ​​the FPC substrate is covered with insulating tape, and then treated in a plasma cleaner to activate its surface to a hydrophilic state for easy bonding with PDMS;

[0093] S14. Pour the degassed PDMS onto the surface of the chip substrate and spin-coat it in two steps; the first step is to accelerate the PDMS from 100 r / s to 500 rpm and then spin-coat it at this speed for 10 seconds; the second step is to accelerate the PDMS from 300 r / s to 6000 rpm and then spin-coat it at this speed for 60 seconds. After the above process, a PDMS thin layer with a thickness of approximately 3 μm can be obtained. Figure 4 As shown, it is used to serve as the first PDMS adhesion layer and the second PDMS adhesion layer. Specifically, the process parameters of the spin coating can be adjusted based on the PDMS thin layer to be obtained, and this adjustment is a predictable adjustment of the spin coating process.

[0094] S15. Place the spin-coated PDMS chip substrate on a hot plate and heat it at 80°C until the PDMS thin layer is solidified.

[0095] Furthermore, the processing of the hydrophobic layer specifically includes the following steps:

[0096] S21. Cutting the PI dielectric layer film and the ITO-PET film into specified sizes according to usage requirements;

[0097] S22. Take a clean glass sheet of appropriate size, spray a certain amount of ethanol on the surface of the glass sheet, then attach the PI film and ITO-PET film to the surface of the glass sheet to keep it flat, then wipe the PI film and ITO-PET film with alcohol cotton to remove any dirt and wipe the film surface dry with dust-free paper;

[0098] S23. Use a pipette to draw a Pyflon T8 solution with a solid content of 1% onto the surface of the PI film and spin-coat it in two steps; in the first step, accelerate the solution from 100 r / s to 500 rpm and then spin-coat it at this speed for 20 seconds; in the second step, accelerate the solution from 300 r / s to 1500 rpm and then spin-coat it at this speed for 60 seconds. After this processing technology, a hydrophobic layer with a thickness of about 400 nm can be obtained.

[0099] S24. Place the spin-coated glass sheet with the PI dielectric film and the ITO-PET film on a heating plate and heat it to fully evaporate the solvent in the Pyflon T8 coating with a solid content of 1%. The heating is carried out in two steps: the first step is heating at 80°C for 10 minutes, and the second step is heating at 150°C for 30 minutes. The glass sheet with the ITO-PET film also needs to be heated, and the heating parameter is heating at 70°C for 1 hour.

[0100] After completing the structural processing of each part of the above-mentioned chip, assemble the chip, stick a conductive tape of about 20mm*3mm on the lower electrode layer, and carefully buckle the upper plate of the chip on the conductive tape. When replacing the PI dielectric film and ITO-PET film, use tweezers to carefully lift the upper plate of the chip, use tweezers to carefully peel off the used film and re-attach a new film. Before bonding, you can spray a small amount of alcohol on the first PDMS adhesion layer and the second PDMS adhesion layer to eliminate static electricity.

[0101] Example 2

[0102] The hydrophobic layer can be processed by ultrasonic spraying, which includes the following steps:

[0103] S1. Prepare two 150mm*150mm glass plates and three 50mm*50mm glass plates. Wipe the glass surfaces with anhydrous ethanol to remove impurities. Cut A4-sized PI films with a thickness of 5μm and 3μm into sizes of 150mm*150mm and 5mm*5mm, respectively.

[0104] S2. Spray a certain amount of anhydrous ethanol on the surface of a clean glass slide. Carefully transfer the above film to the corresponding glass slide surface using tweezers, and ensure that the film and the glass surface are completely bonded;

[0105] S3. The glass with the PI film was placed on the spraying bottom plate of the ultrasonic sprayer; the ultrasonic atomizing spraying equipment was started, and a 1% Pyflon T8 solution was used as a slurry. The slurry was sprayed at a discharge rate of 0.3ml / min at a carrier gas pressure of 0.03Mpa, using a cross-spraying method and sprayed 4 times;

[0106] S4. The heating plate of the spray coater is then started, and the substrate is heated at 150° C. for 1 h to evaporate the solvent to obtain a PI film containing a hydrophobic layer.

[0107] The present invention can effectively solve the problem of residual sample adhesion affecting chip repeatability in the current field of digital microfluidic detection and manipulation, while effectively reducing the high cost of directly replacing or cleaning the entire chip. In addition, it can also achieve customization of the hydrophobic dielectric area, providing a feasible solution to problems in the field.

[0108] Under the aforementioned processing indicators, the voltage required for the digital microfluidic chip to achieve droplet movement is approximately 110V, and the voltage required to achieve droplet splitting is approximately 130V.

[0109] The methods in the two embodiments above can both achieve good hydrophobic layer processing effects. The contact angle comparison of the PI film before and after the hydrophobic treatment is shown in FIG. Figure 6As shown in FIG, the contact angle of the PI film before the hydrophobic treatment is about 79°, and the contact angle after the hydrophobic treatment is about 119°. Figure 7 The figure shows the thickness and surface morphology of the hydrophobic layer obtained by the two processing methods. The thickness of the hydrophobic layer obtained by ultrasonic spraying is about 200nm, and the thickness of the hydrophobic layer obtained by spin coating is 400nm. By scanning the surface morphology, a relatively uniform hydrophobic layer can be obtained under both processing methods, and the difference in surface thickness is maintained within 5nm.

[0110] Figure 8 This is a schematic diagram of the operating results of the chip provided by the present invention. Droplets can smoothly complete the four basic operations of dielectric wetting on the chip, achieving precise control of droplet generation, droplet movement, droplet splitting, and droplet merging.

[0111] In summary, this processing method can effectively solve the problem of biological sample residue on current digital microfluidic chips and reduce the cost of digital microfluidic chips, providing a new solution for the rapid industrial development of the digital microfluidics field.

[0112] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A digital microfluidic chip capable of rapidly replacing a hydrophobic dielectric film, characterized in that: The invention comprises a lower plate and an upper plate, and the upper and lower plates are connected by a conductive tape; the lower plate is composed of a multi-layer structure, which includes, from bottom to top, an FPC substrate, an electrode layer, a first PDMS adhesion layer, a PI dielectric film, and a first hydrophobic layer, wherein the PI dielectric film and the first hydrophobic layer constitute a replaceable hydrophobic dielectric film; the upper plate includes, from bottom to top, a second hydrophobic layer, an ITO-PET film, a second PDMS adhesion layer, and a glass substrate; The second PDMS adhesion layer and the first PDMS adhesion layer are respectively processed on the FPC substrate surface of the lower electrode plate and the glass substrate of the upper electrode plate by spin coating; After constructing a hydrophobic layer on the surface of the PI dielectric film and the ITO-PET film, the films are respectively attached to the first PDMS adhesive layer and the second PDMS adhesive layer; The hydrophobic layer is a Pyflon T8 hydrophobic coating with a solid content of 1%, which is processed on the PI dielectric film and the ITO-PET film by spin coating or ultrasonic spraying. The thickness of the PI dielectric film is 3-5 μm, and the thickness of the hydrophobic layer is 200-400 nm.

2. The digital microfluidic chip with a rapidly replaceable hydrophobic dielectric film according to claim 1, characterized in that: The electrode layer is processed on the FPC substrate using a microelectronics processing technique according to functional requirements.

3. The digital microfluidic chip with a rapidly replaceable hydrophobic dielectric film according to claim 1, characterized in that: The PDMS adhesion layer was processed by spin coating and curing, and the thickness of the PDMS adhesion layer was 3~4μm.

4. The digital microfluidic chip with a rapidly replaceable hydrophobic dielectric film according to claim 1, characterized in that: The thickness of the conductive tape is 150-300 μm.

5. A method for preparing a digital microfluidic chip with a rapidly replaceable hydrophobic dielectric film according to any one of claims 1 to 4, characterized in that: The steps include: The non-droplet manipulation area on the FPC substrate with the electrode layer is covered with insulating tape for isolation, and PDMS is spin-coated on the surface of the FPC substrate / glass substrate. The PDMS is then heated to solidify, and the insulating tape is then removed to complete the processing of the PDMS adhesion layer. The PI dielectric film and the ITO-PET film were attached to the surfaces of separate glass sheets respectively; and a Pyflon T8 solution with a solid content of 1% was spin-coated on the surfaces of the PI dielectric film and the ITO-PET film respectively; and then heated to complete the processing of the hydrophobic layer.

6. The method according to claim 5, characterized in that The processing of the PDMS adhesion layer specifically includes the following steps: S11. Soak the FPC substrate in anhydrous ethanol to clean it; S12. Prepare a PDMS system with PDMS and a curing agent, stir thoroughly, and place in a vacuum chamber to evacuate until there are no bubbles. S13. The non-droplet manipulation area of ​​the FPC substrate was covered with insulating tape and then placed in a plasma cleaner to activate its surface; S14. The degassed PDMS is poured onto the surface of the activated area of ​​the FPC substrate / the upper plate glass substrate surface, and spin-coated in two steps; S15. Heat the spin-coated PDMS lower plate FPC substrate and upper plate glass substrate on a hot plate at 80-85°C until the PDMS thin layer solidifies and forms a permanent bond with the active area surface.

7. The method according to claim 5, characterized in that The processing of the hydrophobic layer specifically includes the following steps: S21. Cut the PI dielectric film and ITO-PET film into specified sizes according to usage requirements; S22. Take a clean glass sheet of appropriate size, spray a certain amount of ethanol on the surface of the glass sheet with a spray bottle, then blow it dry with nitrogen. Attach the PI dielectric film and ITO-PET film to the surface of the glass sheet, then wipe the PI dielectric film and ITO-PET film with alcohol cotton to remove any debris and wipe the film surface dry with dust-free paper; S23. Using a pipette, a 1-6% Pyflon T8 solution is applied to the surface of the PI dielectric film and spin-coated in two steps. S24. Place the spin-coated glass sheet with the PI dielectric film on a hot plate and heat it to fully evaporate the solvent in the Pyflon coating. This heating step is performed in two steps. The glass sheet with the ITO-PET film also requires heating.

8. The method according to claim 5, characterized in that The hydrophobic layer can be processed specifically by ultrasonic spraying.

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