Micro-fluidic chip in-mold fusion bonding method based on microelectrode

Abstract

The invention provides a micro-fluidic chip in-mold fusion bonding method based on a microelectrode. The method comprises the following steps: closing a first mold and a second mold; mold injection molding; maintaining the pressure of the mold and cooling; the mold is opened, and the injection molding runner is ejected out through an ejection mechanism; the first mold moves to enable the cover plate or the substrate to be aligned with the substrate or the cover plate on the second mold; the microelectrode clamping mechanism grabs the microelectrode and moves the microelectrode into the mold, and the microelectrode is aligned with the surface of the substrate in a high-precision mode; the first mold and the second mold are closed, and the bonding power supply is in contact communication with the microelectrode through the switch for fusion bonding; cutting off the bonding power supply, and cooling the mold; and the first mold is separated from the second mold, and the ejection mechanism ejects the finally formed and bonded micro-fluidic chip out of the mold. According to the invention, additional steps generated by a plurality of molds or external operation are simplified, so that the production process of the microfluidic chip is simplified; and meanwhile, the bonding efficiency is high, the bonding is reliable, and the processing efficiency and quality of the micro-fluidic chip are remarkably improved.

Description

Technical Field

[0001] The invention relates to the technical field of microfluidic chip manufacturing, and in particular to a microelectrode-based in-mold melt bonding method for a microfluidic chip. Background Art

[0002] Microfluidic chips are micro-devices that integrate microchannel networks and micromechanical structures, designed to precisely control the movement and reaction of microfluids and particles at the micrometer scale. These devices combine micro-nanotechnology with biomedical science and have many advantages, such as high efficiency, precise control, miniaturization, and the ability to perform complex analysis and synthesis on a single platform. Their wide range of applications, from drug delivery systems, diagnostic tests to environmental monitoring and lab-on-a-chip devices, demonstrates their diversity and importance in advancing biomedical and analytical research. However, even though the manufacturing process of microfluidic chips has been greatly developed, their widespread application and marketization are still limited by issues such as the reliability, repeatability, and cost-effectiveness of molding and bonding technologies.

[0003] There are many kinds of molding and bonding methods for microfluidic chips, each with its own advantages and disadvantages. The selection of a suitable process needs to be determined based on factors such as the chip's material, application scenario, batch requirements, and cost. Among them, injection molding, as an important way to commercialize microfluidic chips, can meet the requirements of mass production, low cost, high precision, and material diversity. This technology is particularly outstanding in improving production efficiency, reducing production costs, ensuring product consistency, and adapting to complex structures and functional designs. In addition, injection molding can be combined with other technologies to further expand its application potential in microfluidic chip manufacturing. For example: injection molding combined with hot pressing bonding technology, injection molding combined with solvent bonding technology, etc. Therefore, the injection molding process is considered to be one of the ideal choices for microfluidic chips to move towards commercialization and wide application in the market.

[0004] The above solutions are based on the combination of injection molding and bonding technology. However, in-mold hot pressing and solvent bonding face challenges such as high mold processing cost, low heating efficiency, solvent residue, microchannel deformation and easy clogging. Therefore, a high-efficiency and reliable bonding solution is urgently needed. Summary of the invention

[0005] The purpose of the present invention is to provide a microfluidic chip bonding solution with high bonding strength, fast bonding efficiency and small microstructure deformation in view of the deficiencies existing in the above-mentioned background technology.

[0006] In order to achieve the above object, the present invention provides a microfluidic chip in-mold melt bonding method based on microelectrodes, comprising the following steps: S1, preparing a first mold and a second mold that match each other, and closing the first mold and the second mold; S2, injecting molten thermoplastic material into the mold through an injection molding machine to fill the mold cavity to form the initial form of the base sheet and the cover sheet; S3, the mold maintains pressure and cools; S4, separating the first mold from the second mold to allow the injection molded part to leak out, and ejecting the injection runner through an ejection mechanism, while the base sheet and the cover sheet remain in the corresponding mold cavity; S5, controlling the first mold to move so that the cover sheet or substrate on the first mold is aligned with the substrate or cover sheet on the second mold; S6, grabbing the microelectrode through the microelectrode clamping mechanism and moving it into the mold, accurately placing the microelectrode at a preset position to ensure the alignment accuracy between the microelectrode and the substrate surface, and then resetting the microelectrode clamping mechanism; S7, the first mold and the second mold are closed, the bonding power source is connected to the microelectrode through the switch, the microelectrode is energized to generate local heating, and the surface layer of the substrate is partially melted; S8, the bonding power is turned off and the mold is cooled; S9, the first mold is separated from the second mold, and the ejection mechanism ejects the finally formed and bonded microfluidic chip from the mold.

[0007] Furthermore, the cores of the first mold and the second mold are both replaceable, a cavity for injection molding of the cover sheet is arranged at a preset position of the first mold, and a cavity for injection molding of the substrate is arranged at a preset position of the second mold.

[0008] Furthermore, the first mold is provided with an injection port, and the injection port is connected to the cavity after the first mold and the second mold are closed.

[0009] Furthermore, the ejection mechanism is provided with at least two ejection ends capable of independently controlling extension and contraction, and the ejection ends correspond to the positions of the cavity for injection molding of the substrate and the injection flow channel.

[0010] Furthermore, the ejection mechanism in S4 ejects the injection runner at the ejection end of the injection runner position.

[0011] Furthermore, the first mold and the second mold are respectively mounted on different mold plates of a mold machine, and the mold machine can control the movement of the mold plates to move or rotate the first mold until the cover sheet is aligned with the substrate.

[0012] Furthermore, the microelectrode clamping mechanism electromagnetically adsorbs the microelectrode and places it at a predetermined position; when the microelectrode is in close contact with the substrate, the microelectrode clamping mechanism removes the electromagnetic force, and the microelectrode is fixed by electromagnetic or permanent magnetic adsorption in the mold.

[0013] Furthermore, the switch includes a contact switch, an induction switch, and a time control switch.

[0014] Furthermore, the ejection mechanism in S9 ejects the finally formed and bonded microfluidic chip corresponding to the ejection end of the substrate.

[0015] The present invention also provides another microfluidic chip in-mold melt bonding method based on microelectrodes, comprising the following steps: S1, preparing a first mold and a second mold that match each other, and closing the first mold and the second mold; S2, injecting molten thermoplastic material into the mold through an injection molding machine to fill the mold cavity to form the initial form of the base sheet and the cover sheet; S3, the mold maintains pressure and cools; S4, separating the first mold from the second mold to allow the injection molded part to leak out, and ejecting the injection runner through an ejection mechanism, while the base sheet and the cover sheet remain in the corresponding mold cavity; S5, controlling the first mold to move so that the cover sheet or substrate on the first mold is aligned with the substrate or cover sheet on the second mold; S6, moving the plasma treatment nozzle to a preset position of the mold and aligning it with the substrate and the cover sheet; S7, performing plasma scanning spray coating on the substrate and the cover sheet; S8, closing the first mold and the second mold, maintaining pressure at a preset temperature, and completing bonding after a preset time; S9, the first mold is separated from the second mold, and the ejection mechanism ejects the finally formed and bonded microfluidic chip from the mold.

[0016] The above scheme of the present invention has the following beneficial effects: The microelectrode-based in-mold melt bonding method for a microfluidic chip provided by the present invention completes injection molding and melt bonding in the same mold, simplifies the extra steps generated by multiple molds or external operations, such as cleaning and drying steps, thereby simplifying the production process of the microfluidic chip; the bonding is completed by locally heating the substrate surface by microelectrode heating, the bonding efficiency is high and the bonding is reliable, and the efficiency and quality of microfluidic chip processing are significantly improved; Other beneficial effects of the present invention will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a flow chart of the steps of Example 1 of the present invention; Figure 2 It is a schematic diagram of S1 in Example 1 of the present invention; Figure 3 This is a schematic diagram of S2 in Example 1 of the present invention; Figure 4 This is a schematic diagram of S4 in Example 1 of the present invention; Figure 5 This is a schematic diagram of S6 in Example 1 of the present invention; Figure 6 This is a schematic diagram of S7 in Example 1 of the present invention; Figure 7 This is a schematic diagram of S9 in Example 1 of the present invention; Figure 8 This is a flow chart of the steps of Example 3 of the present invention; Fig. 9 This is a schematic diagram of S6 in Example 3 of the present invention.

[0018] [Description of Reference Numerals] 1-first mold; 2-second mold; 3-cover plate; 4-substrate; 5-injection port; 6-injection flow channel; 7-ejection mechanism; 8-microelectrode; 9-microelectrode clamping mechanism; 10-trigger contact switch; 11-injection molding machine; 12-plasma treatment nozzle. DETAILED DESCRIPTION

[0019] The following describes the embodiments of the present disclosure through specific examples, and those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0020] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0021] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the present disclosure, and the illustrations only show the components related to the present disclosure rather than the number, shape and size of the components in actual implementation. The type, quantity and proportion of each component in actual implementation may be changed at will, and the component layout type may also be more complicated. In addition, in the following description, specific details are provided to facilitate a thorough understanding of the examples. However, those skilled in the art will understand that the aspects described can be practiced without these specific details.

[0022] Example 1 like Figure 1 As shown, Embodiment 1 of the present invention provides a microfluidic chip in-mold melt bonding method based on microelectrodes, which specifically includes the following steps: S1, prepare the matching first mold 1 and second mold 2, perform the first mold closing, close the first mold 1 and the second mold 2, and prepare for injection molding. Figure 2 shown.

[0023] Among them, the cores of the first mold 1 and the second mold 2 can be replaced to adapt to the injection molding of different microfluidic chips. The preset position of the first mold 1 is provided with a cavity for injection molding of the cover sheet 3, and the preset position of the second mold 2 is provided with a cavity for injection molding of the substrate 4. And the two are not aligned during the first mold closing process. Of course, the cover sheet 3 can also be at the preset position of the second mold 2, and the substrate 4 can be correspondingly at the preset position of the first mold 1, which is not limited here.

[0024] It should be noted that the microfluidic chip is composed of a substrate 4 and a cover sheet 3. The substrate 4 contains a microchannel structure, which is formed by a corresponding cavity. The surface of the cover sheet 3 is usually smooth and is subsequently connected together by bonding.

[0025] S2, injecting the molten thermoplastic material into the mold through the injection molding machine 11, filling the mold cavity to form the initial shape of the base sheet 4 and the cover sheet 3. Figure 3 shown.

[0026] The first mold 1 is provided with an injection port 5 , which is connected to the mold cavity after the two molds are molded together. During the injection process, the molten thermoplastic material gradually fills the mold cavity, thereby also filling the positions of the base sheet 4 and the cover sheet 3 .

[0027] It should be noted that thermoplastic materials can include polymethyl methacrylate (PMMA), cycloolefin copolymer (COC), polystyrene (PS), etc., all of which are organic polymer materials and have the advantage of lower cost compared to traditional materials.

[0028] When the first mold 1 and the second mold 2 are closed, the cavities for injection molding of the base sheet 4 and the cover sheet 3 are both connected to the injection runner 6, so the molten thermoplastic material injected from the injection port 5 will flow into the two cavities.

[0029] S3, the mold is kept under pressure and cooled. The molten thermoplastic material is gradually cooled and formed during the process of filling and cooling under pressure, and the structural integrity and precision of the base sheet 4 and the cover sheet 3 are ensured through the pressure-maintaining process.

[0030] S4, the first mold opening is performed, the first mold 1 is separated from the second mold 2, so that the injection molded part leaks out, and the injection flow channel 6 (thermoplastic material) is ejected through the ejection mechanism 7 connected to the second mold 2, while the base sheet 4 and the cover sheet 3 are still retained in the corresponding mold cavity. Figure 4 shown.

[0031] It should be noted that in the present embodiment, the ejection mechanism 7 is provided with two ejection ends that can be independently controlled to be retracted, and the ejection ends correspond to the cavity of the injection molding of the substrate 4 and the position of the injection molding runner 6. In this step, only the ejection end at the position of the injection molding runner 6 operates to eject the injection molding runner 6, and the other ejection end does not operate. Since the thickness of the connection position between the cavity of the injection molding of the substrate 4 and the cover sheet 3 and the injection molding runner 6 is not large, the injection molding runner 6 can be separated from the substrate 4 and the cover sheet 3 during the mold opening and ejection process, thereby remaining in the corresponding mold cavity. Of course, if the injection molding runner 6 cannot be separated from the substrate 4 and the cover sheet 3, it can also be separated by cutting after the mold is opened.

[0032] S5, aligning the cover sheet 3 on the first mold 1 with the substrate 4 on the second mold 2 by moving or rotating, so as to prepare for bonding of the microelectrode 8.

[0033] In the above steps, the substrate 4 and the cover sheet 3 are injection molded at different positions to avoid mutual interference during molding. The cover sheet 3 and the substrate 4 need to be aligned during subsequent bonding, so the first mold 1 needs to be moved to align the cover sheet 3 on the first mold 1 with the substrate 4 on the second mold 2. The first mold 1 and the second mold 2 can be installed on different mold plates of the mold machine. The mold machine can control the movement of the mold plate to move or rotate the first mold 1 until the cover sheet 3 is aligned with the substrate 4.

[0034] S6, the microelectrode 8 is grasped by the microelectrode clamping mechanism 9 (manipulator) and moved into the mold, and the microelectrode 8 is accurately placed at the preset position (of the substrate 4), ensuring the alignment accuracy between the microelectrode 8 and the surface of the substrate 4, and the microelectrode clamping mechanism 9 is then reset to the first mold 1 to close the mold and avoid bonding. Figure 5 shown.

[0035] It should be noted that for iron, cobalt or nickel electrodes made of ferromagnetic materials, the microelectrode clamping mechanism 9 can electromagnetically adsorb the microelectrode 8 and place it at a predetermined position; when the microelectrode 8 is in close contact with the substrate 4, the electromagnetic force is removed, and the microelectrode 8 is adsorbed by the electromagnetic or permanent magnet in the mold and fixed at the predetermined position; at the same time, a high-resolution visual system (such as a CCD camera) can be integrated on the microelectrode clamping mechanism 9 to monitor the position of the microelectrode 8 in real time, and accurately identify the relative coordinates of the microelectrode 8 and the substrate 4 through image processing algorithms. Obviously, for the microelectrode clamping mechanism 9, it is necessary to use a high-precision motion module to ensure the accuracy of the movement, thereby ensuring the accuracy of the alignment of the microelectrode 8.

[0036] S7, the second mold closing is performed, the first mold 1 and the second mold 2 are closed, the bonding power source is connected to the microelectrode 8 through the trigger contact switch 10, the microelectrode 8 is energized to generate local heating, and the surface layer of the substrate 4 is partially melted by the heat energy, so as to facilitate the bonding of the microfluidic chip. Figure 6 shown.

[0037] It should be noted that in this embodiment, the trigger contact switch 10 is arranged on the first mold 1. When the first mold 1 and the second mold 2 are molded together, the trigger contact switch 10 on the first mold 1 contacts the microelectrode 8 to form a loop, and a current is generated under the action of the bonding power supply. The microelectrode 8 itself has resistance, so it can convert electrical energy into thermal energy when powered on, thereby locally heating and locally melting the surface layer of the substrate 4, so that the substrate 4, the microelectrode 8, and the cover sheet 3 are bonded. Of course, in other embodiments, an induction switch, a time control switch, etc. can also be used.

[0038] S8, after bonding is completed, the bonding power supply is turned off and cooling begins to ensure the stability and strength of the bonding part of the microfluidic chip. Among them, this process is also carried out in the mold clamping state to stabilize the environment when the microfluidic chip is cooled after bonding, thereby improving the overall quality of the microfluidic chip.

[0039] S9, the second mold opening is performed, the first mold 1 is separated from the second mold 2, and the finally formed and bonded microfluidic chip is ejected from the mold by the ejection mechanism 7. In this step, the ejection mechanism 7 operates at the ejection end of the corresponding substrate 4 to eject the bonded microfluidic chip, thereby obtaining a finished microfluidic chip. Figure 7 shown.

[0040] As described above, the microelectrode-based in-mold melt bonding method for a microfluidic chip provided in this embodiment completes injection molding and melt bonding in the same mold, simplifies the additional steps generated by multiple molds or external operations, such as cleaning and drying steps, thereby simplifying the production process of the microfluidic chip. The bonding is completed by locally heating the surface of the substrate 4 by heating the microelectrode 8, with high bonding efficiency and reliable bonding, which significantly improves the efficiency and quality of microfluidic chip processing.

[0041] It is worth mentioning that, using the method provided in this embodiment, the design and quality of the microelectrode 8 structure have a significant impact on the final bonding quality of the microfluidic chip. For example, the material of the microelectrode 8 can be a metal, such as gold, silver or platinum, or other non-metallic conductive materials, such as carbon. The microelectrode 8 preparation process, such as electrodeposition, electrochemical etching, laser drawing and internal filling, as well as self-assembly technology, chemical vapor deposition, template method, ion beam etching technology, screen printing, ultraviolet light irradiation chemical plating technology, 3D printing, atomization deposition and other flexible circuit manufacturing processes. The processing accuracy and limit size of the microelectrode 8, whether the microelectrode 8 has a substrate, the substrate material, the substrate thickness, the secondary processing of the substrate, etc.

[0042] Before S7 is performed, the electricity, heat and stress to which the microelectrode 8 is subjected during the bonding process can be analyzed by simulation. The simulation model is defined to accurately reflect the actual physical characteristics and behaviors of the microelectrode 8 during heating and bonding; the material microstructure parameters are set, including various properties of the materials used in bonding, such as thermal conductivity, electrical conductivity and mechanical strength; the electro-thermal-structural mechanics simulation boundary conditions are set, including but not limited to: potential / current, bonding pressure. After obtaining the simulation results, the temperature distribution of the microelectrode 8, the potential loss density, the thermal distribution of the microfluidic chip and the microchannel deformation are analyzed. For example, the microelectrode 8 material, bonding power supply and power-on time can be optimized through the electrode temperature distribution to avoid overheating or insufficient heating; the microelectrode 8 structure, size, etc. can be optimized according to the potential loss density to avoid local heat dissipation; the temperature gradient can be reasonably arranged by optimizing the position of the microelectrode 8 through the thermal distribution of the microfluidic chip, so as to ensure that the polymer around the microelectrode 8 is melted and the temperature around the microchannel is lower than the glass transition temperature; the bonding pressure can be optimized in combination with the microchannel deformation. Finally, based on the above analysis, it is determined whether the microelectrode 8 needs to be further optimized. If necessary, the design of the microelectrode 8 and the bonding process parameters are optimized, and the accuracy of the microelectrode clamping mechanism 9 is also optimized.

[0043] Based on the same inventive concept, this embodiment also provides a microfluidic chip in-mold melt bonding system based on microelectrodes, including a first mold 1 and a second mold 2, and also includes an injection molding machine 11, an ejection mechanism 7, a microelectrode clamping mechanism 9, etc. The specific configuration of these modules has been mentioned in the previous text and will not be repeated here. Since the system has the same inventive concept and beneficial effects as the aforementioned microfluidic chip in-mold melt bonding method based on microelectrodes 8, it will not be repeated here.

[0044] Example 2 Embodiment 2 of the present invention provides another microfluidic chip in-mold melt bonding method based on microelectrodes. The main difference from Embodiment 1 is that plasma scanning is added to the original process. The plasma is equivalent to bombarding hydroxyl groups on the surface of substrate 3 and cover sheet 4. On the one hand, the microelectrodes are assisted to complete the bonding through intermolecular forces; on the other hand, after plasma treatment, the microchannels of the microfluidic chip become hydrophilic, improving the flow performance of the liquid in the microchannels. Optionally, when the surface of the microfluidic chip is treated with fluorine-containing plasma, the hydrophobicity of the microchannels can also be increased.

[0045] Based on this, the following steps are added between S5 and S6 of Example 1: S6, moving the plasma treatment nozzle 12 to a preset position of the mold and aligning it with the substrate 3 and the cover sheet 4, such as Fig. 9 As shown; S7, performing plasma scanning spraying on the substrate 3 and the cover sheet 4; Therefore, Example 2 provides a bonding solution different from Example 1, which can also achieve the effect of in-mold bonding of the microfluidic chip and ensure quality.

[0046] Example 3 like Figure 8 As shown, Example 3 of the present invention provides another microfluidic chip in-mold melt bonding method based on microelectrodes, which is mainly different from Example 1 in that plasma bonding is used instead of microelectrode bonding, and plasma is equivalent to bombarding hydroxyl groups on the surface of substrate 3 and cover sheet 4, and then forming bonds through intermolecular forces. When plasma bonding is performed, it is not necessary to rely on the power supply of the bonding power supply to heat and melt.

[0047] Based on this, S6-S8 of Example 1 are replaced by: S6, moving the plasma treatment nozzle 12 to a preset position of the mold and aligning it with the substrate 3 and the cover sheet 4, such as Fig. 9 As shown (where Fig. 9 The bond power on does not work); S7, performing plasma scanning spraying on the substrate 3 and the cover sheet 4; S8, closing the first mold 1 and the second mold 2, maintaining pressure at a preset temperature, and completing bonding after a preset time.

[0048] Therefore, Example 3 provides a bonding solution different from Example 1, which can also achieve the effect of in-mold bonding of the microfluidic chip and ensure quality.

[0049] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

Claims

1. A microfluidic chip in-mold melt bonding method based on microelectrodes, characterized in that: The steps include: S1, preparing a first mold and a second mold that match each other, and closing the first mold and the second mold; S2, injecting molten thermoplastic material into the mold through an injection molding machine to fill the mold cavity to form the initial form of the base sheet and the cover sheet; S3, the mold maintains pressure and cools; S4, separating the first mold from the second mold to allow the injection molded part to leak out, and ejecting the injection runner through an ejection mechanism, while the base sheet and the cover sheet remain in the corresponding mold cavity; S5, controlling the first mold to move so that the cover sheet or substrate on the first mold is aligned with the substrate or cover sheet on the second mold; S6, grabbing the microelectrode through the microelectrode clamping mechanism and moving it into the mold, accurately placing the microelectrode at a preset position to ensure the alignment accuracy between the microelectrode and the substrate surface, and then resetting the microelectrode clamping mechanism; S7, the first mold and the second mold are closed, the bonding power source is connected to the microelectrode through the switch, the microelectrode is energized to generate local heating, and the surface layer of the substrate is partially melted; S8, the bonding power is turned off and the mold is cooled; S9, the first mold is separated from the second mold, and the ejection mechanism ejects the finally formed and bonded microfluidic chip from the mold.

2. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 1, characterized in that: The cores of the first mold and the second mold are both replaceable. A cavity for injection molding of the cover sheet is arranged at a preset position of the first mold, and a cavity for injection molding of the substrate sheet is arranged at a preset position of the second mold.

3. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 1, characterized in that: The first mold is provided with an injection port, and the injection port is communicated with the mold cavity after the first mold and the second mold are molded together.

4. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 1, characterized in that: The ejection mechanism is provided with at least two ejection ends capable of independently controlling extension and contraction, and the ejection ends correspond to the positions of the mold cavity and the injection flow channel of the substrate injection molding.

5. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 4, characterized in that: The ejection mechanism in S4 ejects the injection runner at the ejection end of the injection runner position.

6. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 1, characterized in that: The first mold and the second mold are respectively mounted on different mold plates of a mold machine, and the mold machine can control the movement of the mold plates to move or rotate the first mold until the cover sheet is aligned with the substrate.

7. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 1, characterized in that: The microelectrode clamping mechanism electromagnetically absorbs the microelectrode and places it at a predetermined position; when the microelectrode is in close contact with the substrate, the microelectrode clamping mechanism removes the electromagnetic force, and the microelectrode is fixed by electromagnetic or permanent magnetic absorption in the mold.

8. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 1, characterized in that: The switches include contact switches, induction switches and time control switches.

9. The method for in-mold melt bonding of a microfluidic chip based on microelectrodes according to claim 4, characterized in that: The ejection mechanism in S9 ejects the finally formed and bonded microfluidic chip corresponding to the ejection end of the substrate.

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