A preparation method for a master mold of an amorphous alloy microfluidic chip

Abstract

A preparation method of an amorphous alloy microfluidic chip master mold. First, prepare mold steel and an amorphous alloy sample, and utilize the superplasticity characteristics of the amorphous alloy for thermoplastic forming to replicate the surface topography of the mold steel mold. After cooling and demolding, an amorphous alloy microfluidic chip master mold is obtained. In addition, the amorphous alloy micro mold prepared by the above method is used for thermocompression forming of a polymer, and after cooling and demolding, a microchannel with a complete shape and clear contour is obtained. Then, the amorphous alloy micro mold is crystallized to obtain a mold with high-temperature stability, and glass is thermocompression formed at a certain temperature, and after cooling and demolding, a microchannel with a complete shape and clear contour is obtained. The present invention can prepare amorphous alloy microfluidic chip master molds of different sizes by adjusting the channel size on the surface of the mold steel, thereby thermocompression forming polymers, glass, etc., and can realize the rapid and batch production of microchannels, thereby improving efficiency and reducing costs.

Description

Technical Field

[0001] The present invention belongs to the technical field of hot embossing forming of amorphous alloy molds, and particularly relates to the preparation technology of amorphous alloy molds. Background Art

[0002] Microfluidic chips are mainly composed of some microchannels. It integrates many disciplines such as mechanics, electronics, chemistry, biology, and new materials, and is a new interdisciplinary field. Microfluidic chip technology can miniaturize the processes of sample preparation, separation, reaction, detection, etc. in biological, chemical, and medical analysis processes onto a chip of several square centimeters, so it is also called a laboratory on a chip. It can not only greatly reduce the consumption of precious biological samples and reagents to the microliter or even nanoliter level, but also increase the analysis speed by ten to a hundred times and reduce the cost by ten to a hundred times. Therefore, it is widely used in research fields such as biology, medicine, and chemical analysis.

[0003] Microchannels are the key to the fabrication of microfluidic chips. Currently, the main materials for fabricating microfluidic chips are single-crystalline silicon wafers, quartz, glass, organic polymer polymers, etc. The processing methods for single-crystalline silicon wafers, quartz, and glass microfluidic chips mainly include micro-milling, wet / dry etching, laser processing, etc., while the methods for preparing microchannels of thermoplastic polymers mainly include molding, injection molding, hot embossing, soft etching, etc. Among the many materials and methods for fabricating microfluidic chips, the use of hot embossing to prepare thermoplastic polymer microstructures has the advantages of simple process, simple equipment, convenient operation, low cost, etc., and is suitable for mass production, and is the most widely used in the fabrication of microfluidic chips. Glass-based micro-devices have good performance in terms of thermal stability, chemical inertness, transparency, and hardness, and can be applied to acidic and high-temperature working conditions, which also makes it one of the preferred substrates for fabricating microfluidic chips. At the same time, researchers have found that in high-precision manufacturing technologies, hot embossing is also one of the most promising and effective methods for fabricating glass microstructures.

[0004] The preparation of a microfluidic chip by hot embossing requires replicating the microstructures on the male mold onto the substrate material. In practical applications, the quality of the male mold is often required to be high to ensure that it can be reused multiple times and has a long service life. Therefore, the material selection of the mold is of utmost importance. Currently, rigid superhard materials are selected as the male mold. Silicon-based materials mainly include silicon, silicon dioxide, silicon nitride, and quartz; non-silicon-based materials include single-crystal diamond, sapphire, indium tin oxide, chromium, nickel, and other metals, as well as some relatively hard materials with a high Young's modulus. Currently, micro-milling, electrical discharge machining (EDM), laser machining, diamond cutting, and reactive ion etching are common processing methods for mold inserts. However, their applications are limited by disadvantages such as unsatisfactory surface quality, low machining accuracy, low machining efficiency, and high costs. For example, with EDM and laser machining technologies, hard materials can be easily and effectively removed, but the surface quality is poor. For ion etching technology, the surface quality is good, but it is difficult to improve the machining efficiency. Moreover, silicon-based materials, in addition to high processing costs and difficulty in machining, are physically brittle and are often disposable consumables, making it difficult to reuse them periodically, which greatly increases the production cost.

[0005] There are no grains inside the amorphous alloy. Its microstructure of "short-range order and long-range disorder" overcomes the grain size effect, enabling it to have excellent performance in filling microstructures. In addition, bulk amorphous alloys have a low flow resistance in the supercooled liquid region, which can greatly improve the manufacturing accuracy and forming quality of micro-surface components, making it an ideal material for micro-structure manufacturing. At the same time, compared with traditional metals, this material has a series of more excellent properties, which also makes it an ideal material for the preparation of microfluidic chips. Summary of the Invention

[0006] The purpose of the present invention is to provide a method for preparing a master mold of an amorphous alloy microfluidic chip.

[0007] The present invention is a method for preparing a master mold of an amorphous alloy microfluidic chip, and its steps include:

[0008] Step (1) Preparation of the primary master mold: Using a precision engraving machine, microchannels with concave channels are processed on the surface of RM2 die steel, and the primary master mold of the concave channels is prepared according to requirements. The width of the microchannels is 100 - 500 μm, the depth of the channels is 100 - 500 μm, the diameter at the disc is 0.2 - 2 mm, and the depth at the disc is 100 - 500 μm;

[0009] Step (2): Stack and fix the amorphous alloy sample and the primary master mold in the mold holder, place the assembled mold holder in a high and low temperature mechanical property testing machine, heat up to the target temperature in the supercooled liquid region of the amorphous alloy, and perform hot pressing forming; the positioning punch is in direct contact with the amorphous sample; since the mold core size is larger than the sample, a counterbore is provided at the bottom of the upper mold to fix the mold core; the upper mold and the lower mold are positioned and connected through guide columns.

[0010] Step (3): Cooling and demolding: After hot pressing, cool the mold holder with nitrogen and take out the formed amorphous alloy sample and the primary master mold to obtain the amorphous alloy micro mold of the microchannel male mold. The width of the microchannel is 100 - 500 μm, the channel depth is 100 - 500 μm, the diameter at the disc is 0.2 - 2 mm, and the depth at the disc is 100 - 500 μm.

[0011] The beneficial effects of the present invention are as follows: A method and material for preparing a mold for microfluidic chip imprinting are provided. Compared with the traditional micro mold processing method, this method has a short cycle, high efficiency, and low cost. This material also has more excellent properties compared with traditional metals. At the same time, a method for preparing a polymer and glass microfluidic chip is provided. This preparation method has a simple process and high efficiency. Description of the Drawings

[0012] Figure 1 This is the primary master mold prepared in the embodiment of the present invention. Figure 2 This is the schematic diagram of the assembly of the amorphous alloy sample, the mold, and the mold holder during hot imprinting of the present invention. Figure 3 This is the macroscopic view of the amorphous alloy microfluidic chip master mold prepared by the present invention. Figure 4 This is the SEM morphology of the disc of the amorphous alloy microfluidic chip master mold prepared by the present invention. Figure 5 This is the SEM morphology of the L-shaped right angle of the amorphous alloy microfluidic chip master mold prepared by the present invention. Figure 6 This is the SEM morphology of the U-shaped bend of the amorphous alloy microfluidic chip master mold prepared by the present invention. Figure 7 This is the SEM morphology of the Y-shaped corner of the amorphous alloy microfluidic chip master mold prepared by the present invention. Figure 8 This is the XRD pattern of the amorphous alloy micro mold before high-temperature crystallization of the present invention. Figure 9 This is the XRD pattern of the amorphous alloy micro mold after high-temperature crystallization. Figure 10 This is the polymer microfluidic chip prepared by the present invention. Figure 11 This is the glass microfluidic chip prepared by the present invention. Embodiment

[0013] The present invention is a method for preparing an amorphous alloy microfluidic chip master mold, and its steps include:

[0014] Step (1) Preparation of the primary master mold: Using a precision engraving machine, microchannels with concave channels are machined on the surface of RM2 mold steel, and the primary master mold for preparing the concave channels is machined according to requirements. The width of the microchannels is 100 - 500 μm, the channel depth is 100 - 500 μm, the diameter at the disc is 0.2 - 2 mm, and the depth at the disc is 100 - 500 μm;

[0015] Step (2) Stack and fix the amorphous alloy sample and the primary master mold in the mold holder, and place the assembled mold holder in a high and low temperature mechanical property testing machine. Heat it up to the target temperature in the supercooled liquid region of the amorphous alloy and perform hot pressing forming. The positioning punch is in direct contact with the amorphous sample; since the size of the mold core is larger than the sample, a counterbore is provided at the bottom of the upper mold to fix the mold core; the upper mold and the lower mold are positioned and connected through guide pillars;

[0016] Step (3) Cooling and demolding: After hot pressing, cool the mold holder with nitrogen and take out the formed amorphous alloy sample and the primary master mold to obtain an amorphous alloy micro - mold of the microchannel male mold. The width of the microchannels is 100 - 500 μm, the channel depth is 100 - 500 μm, the diameter at the disc is 0.2 - 2 mm, and the depth at the disc is 100 - 500 μm.

[0017] For the preparation method described above, the minimum clearance of the hole of the positioning punch is a tolerance fit of 0, with a size of 8×8 mm; the positioning punch is in direct contact with the amorphous sample. To ensure convenient placement of the sample, the sample size is cut to 7.8×7.8×3 mm, with a preset margin left from the positioning hole; the size of the mold core is larger than the sample, and a counterbore with a size of 11×11×1.5 mm is provided at the bottom of the upper mold to fix the mold core.

[0018] For the preparation method described above, the prepared primary master mold is placed in the mold holder together with an amorphous alloy sample with the chemical composition formula (Zr 0.6336 Cu 0.1452 Ni 0.1012 Al 0.12 ) 99.4 Y 0.6 . The hot pressing forming is carried out using a high and low temperature mechanical property testing machine, and the micro - channels engraved on the surface of the primary master mold are precisely replicated on the surface of the amorphous alloy to prepare an amorphous alloy micro - mold; (Zr 0.6336 Cu 0.1452 Ni 0.1012 Al 0.12 ) 99.4 Y 0.6 . The hot pressing forming conditions of the amorphous alloy in the high and low temperature mechanical property testing machine are 680 - 730 K / 0.01 - 0.0001 s -1 .

[0019] For the preparation method described above, the primary master mold and an amorphous alloy sample with the chemical composition formula (Zr0.6336 Cu 0.1452 Ni 0.1012 Al 0.12 ) 97.4 Er 2.6 The amorphous alloy sample of 2.6 is assembled in a mold base and hot-pressed using a high and low temperature mechanical property testing machine to prepare an amorphous alloy micro-mold. The hot-pressing conditions are 680 - 720 K / 0.01 - 0.0001 s -1 .

[0020] In the preparation method described above, the primary master mold and the amorphous alloy sample with the chemical composition formula of Zr 61.88 Cu 18 Ni 10.12 Al 10 are assembled in a mold base and hot-pressed using a high and low temperature mechanical property testing machine to prepare an amorphous alloy micro-mold. The hot-pressing conditions are 670 - 730 K / 0.01 - 0.0001 s -1 .

[0021] In the preparation method described above, by utilizing the thermoplasticity of the polymer after heating, an amorphous alloy micro-mold is used as the master mold, and micro-channels are imprinted on the surface of the polymer by hot embossing; the hot embossing temperature range is 390K - 430K, and the strain rate is 0.1 s -1 .

[0022] In the preparation method described above, an amorphous alloy micro-mold is used as the master mold and is subjected to high-temperature crystallization treatment to make it have thermal stability. At the same time, by utilizing the thermoplasticity of the glass after heating, micro-channels are imprinted on the surface of the glass by hot embossing; the crystallization process parameters of the amorphous alloy are: temperature 773 K, that is, above the crystallization temperature, and keep warm for 10 min; the hot embossing temperature is 740 - 770K, and the strain rate is 0.001 s -1 .

[0023] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below in conjunction with embodiments

[0024] Example 1:

[0025] (1) Preparation of the primary master mold:

[0026] The material selected for the primary master mold is RM2 die steel. The die steel is cut into appropriate blocks, and micro-channels are machined on the surface of the steel using a precision engraving machine

[0027] (2) Preparation of the amorphous alloy sample:

[0028] In the implementation process of this specific example, the selected amorphous alloy has the chemical composition formula of (Zr 0.6336 Cu0.1452 Ni 0.1012 Al 0.12 ) 99.4 Y 0.6 , all the selected elements are high-purity metals. The ingredients are prepared according to the atomic ratio of the required components, and the smelting is carried out in a water-cooled copper crucible magnetic levitation smelting furnace, and the smelting environment is protected by argon. To ensure uniform composition, the alloy ingot needs to be smelted at least three times. The copper mold suction casting method is used to prepare an alloy plate with a size of 20×70×3 mm, and it is cut into block samples of the required size by wire cutting. The alloy sample is polished as a whole and the formed surface is polished;

[0029] (3) Amorphous alloy micro-forming process:

[0030] The primary master mold prepared in (1) and the amorphous alloy sample (2) are stacked and assembled in the mold frame. The microchannels carved on the surface of the primary master mold are precisely replicated on the surface of the amorphous alloy using hot pressing technology to prepare an amorphous alloy micro mold. -1 The microforming of amorphous alloys was studied in a high and low temperature mechanical properties testing machine under deformation conditions. The results show that 703 K / 0.001 s -1 It is most suitable to process under

[0031] (4) Preparation of thermoplastic polymer microfluidic chips:

[0032] The thermoplastic polymer PMMA was cut into appropriate sizes, and the amorphous alloy micro mold prepared by (3) was stacked with the thermoplastic PMMA and assembled in the mold frame. The temperature was raised to 423 K using a high and low temperature mechanical properties testing machine with a strain rate of 0.1 s. -1 Hot embossing was performed to replicate the surface pattern of the amorphous alloy micro-mold on the PMMA surface to prepare a polymer microfluidic chip;

[0033] (5) Preparation of glass microfluidic chips:

[0034] D-FK61 glass was cut into appropriate sizes. Since the softening temperature of glass is relatively high, the amorphous alloy micro mold prepared in (3) was first heated to 773 K (above the crystallization temperature) and kept warm for 10 min to change its structure and obtain high-temperature stability. Then, the glass microfluidic chip was prepared according to step (4). The forming temperature was 763 K and the strain rate was 0.001 s -1 .

[0035] Embodiment 2:

[0036] In this embodiment, the preparation of the primary master mold is the same as that in Example 1. The composition of the amorphous alloy is (Zr 0.6336 Cu0.1452 Ni 0.1012 Al 0.12 ) 97.4 Er 2.6 , the preparation method of this amorphous alloy sample is the same as that of Example 1, except that the ingredients are proportioned according to the atomic ratio in the chemical composition formula (Zr 0.6336 Cu 0.1452 Ni 0.1012 Al 0.12 ) 97.4 Er 2.6 .

[0037] Same as Example 1, the primary master mold and the amorphous alloy sample were assembled in a mold frame for forming, and the micro-forming of the amorphous alloy was studied in a high and low temperature mechanical property testing machine under the deformation conditions of 680 - 720 K / 0.01 - 0.0001 s -1 . The results show that it is most suitable to process at 708 K / 0.001 s -1 .

[0038] Using the same method as Example 1, at 423 K, the strain rate was 0.1 s -1 PMMA was hot embossed, and the surface pattern of the amorphous alloy micro-mold was replicated on the surface of PMMA to prepare a polymer microfluidic chip.

[0039] Using the same method as Example 1, the amorphous alloy micro-mold was heated to 773 K and held for crystallization, and then used to emboss D-FK61 glass to prepare a glass microfluidic chip.

[0040] Example 3:

[0041] In this example, the preparation of the primary master mold is the same as that of Example 1. The composition of the amorphous alloy is Zr 61.88 Cu 18 Ni 10.12 Al 10 , the preparation method of this amorphous alloy sample is the same as that of Example 1, except that the ingredients are proportioned according to the atomic ratio in the chemical composition formula Zr 61.88 Cu 18 Ni 10.12 Al 10 .

[0042] Same as Example 1, the primary master mold and the amorphous alloy sample were assembled in a mold frame for forming, and the micro-forming of the amorphous alloy was studied in a high and low temperature mechanical property testing machine under the deformation conditions of 670 - 730 K / 0.01 - 0.0001 s -1 . The results show that it is most suitable to process at 705 K / 0.001 s -1 .

[0043] The same method as in Example 1, at 423 K, the strain rate is 0.1 s -1 Thermal imprinting was performed on PMMA, and the surface pattern of the amorphous alloy micro-mold was replicated on the PMMA surface to fabricate a polymer microfluidic chip.

[0044] Using the same method as in Example 1, the amorphous alloy micro-mold was heated to 773 K and held for crystallization, and then used to imprint D-FK61 glass to fabricate a glass microfluidic chip.

Claims

1. A method for preparing a master mold of an amorphous alloy microfluidic chip, characterized in that The steps include: Step (1) Preparation of the primary master mold: Using a precision engraving machine, microchannels with concave channels are machined on the surface of RM2 mold steel, and the primary master mold for preparing the concave channels is machined according to requirements. The width of the microchannels is 100 - 500 μm, the channel depth is 100 - 500 μm, the diameter at the disc is 0.2 - 2 mm, and the depth at the disc is 100 - 500 μm. Step (2) Stack and fix the amorphous alloy sample and the primary master mold in the mold holder, and place the assembled mold holder in a high and low temperature mechanical property testing machine. Heat it up to the target temperature in the supercooled liquid phase region of the amorphous alloy and perform hot pressing forming. The positioning punch is in direct contact with the amorphous sample; since the size of the mold core is larger than the sample, a counterbore is provided at the bottom of the upper mold to fix the mold core; the upper mold and the lower mold are positioned and connected through guide pillars. Step (3) Cooling and demolding: After hot pressing, cool the mold holder with nitrogen and take out the formed amorphous alloy sample and the primary master mold to obtain an amorphous alloy micro - mold of the microchannel male mold. The width of the microchannels is 100 - 500 μm, the channel depth is 100 - 500 μm, the diameter at the disc is 0.2 - 2 mm, and the depth at the disc is 100 - 500 μm.

2. The method for preparing a master mold of an amorphous alloy microfluidic chip according to claim 1, characterized in that The minimum clearance of the hole of the positioning punch is a tolerance fit of 0, with a size of 8×8 mm; the positioning punch is in direct contact with the amorphous sample. To ensure convenient placement of the sample, the sample size is cut to 7.8×7.8×3 mm, leaving a preset margin from the positioning hole; the size of the mold core is larger than the sample, and a counterbore with a size of 11×11×1.5 mm is provided at the bottom of the upper mold to fix the mold core.

3. The method for preparing a master mold of an amorphous alloy microfluidic chip according to claim 1, characterized in that The prepared primary master mold and the amorphous alloy sample with the chemical composition formula of (Zr 0.6336 Cu 0.1452 Ni 0.1012 Al 0.12 ) 99.4 Y 0.6 are placed in a mold holder, and hot pressing forming is carried out by using a high and low temperature mechanical property testing machine. The microchannels engraved on the surface of the primary master mold are precisely replicated on the surface of the amorphous alloy to prepare an amorphous alloy micro mold; (Zr 0.6336 Cu 0.1452 Ni 0.1012 Al 0.12 ) 99.4 Y 0.6 The hot pressing forming conditions of the amorphous alloy of (Zr -1 in a high and low temperature mechanical property testing machine are 680 - 730 K / 0.01 - 0.0001 s 4. The method for preparing a master mold of an amorphous alloy microfluidic chip according to claim 1, characterized in that Assemble a primary master mold with an amorphous alloy sample of chemical composition formula (Zr 0.6336 Cu 0.1452 Ni 0.1012 Al 0.12 ) 97.4 Er 2.6 in a mold base, and perform hot pressing forming using a high and low temperature mechanical property testing machine to prepare an amorphous alloy micro mold. The hot pressing forming conditions are 680 - 720K / 0.01 - 0.0001s -1 .

5. The method for preparing a master mold of an amorphous alloy microfluidic chip according to claim 1, characterized in that Assemble a primary master mold with an amorphous alloy sample with the chemical composition formula Zr 61.88 Cu 18 Ni 10.12 Al 10 in a mold base, and use a high and low temperature mechanical property testing machine for hot pressing forming to prepare an amorphous alloy micro mold. The hot pressing forming conditions are 670 - 730 K / 0.01 - 0.0001 s -1 .

6. The method for preparing a master mold of an amorphous alloy microfluidic chip according to claim 1, characterized in that: Utilize the thermoplasticity of the polymer after heating, use an amorphous alloy micro-mold as the master mold, and imprint micro-channels on the polymer surface by means of hot embossing; the hot embossing temperature range is 390K - 430K, and the strain rate is 0.1 s -1 .

7. The method for preparing a master mold of an amorphous alloy microfluidic chip according to claim 1, characterized in that: An amorphous alloy micro-mold is used as the master mold and subjected to high-temperature crystallization treatment to make it thermally stable. At the same time, taking advantage of the thermoplasticity of glass after heating, micro-channels are imprinted on the glass surface by hot embossing. The process parameters of the amorphous alloy crystallization are as follows: the temperature is 773 K, that is, above the crystallization temperature, and the heat preservation time is 10 min; the hot embossing temperature is 740 - 770 K, and the strain rate is 0.001 s -1 .

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