A method for manufacturing a micro-fluid pump based on giant magnetostrictive material

Abstract

The application discloses a micro flow pump based on super magnetostrictive material, which is a coil built-in type, and comprises a hollow pump body, a diaphragm arranged at the top of the pump body, a metal coil arranged in the inner cavity of the pump body, a protective layer wrapped outside the metal coil, a super magnetostrictive rod connected to the middle part of the metal coil, and an aluminum electrode arranged at the bottom of the pump body and electrically connected with the metal coil, wherein the super magnetostrictive rod is in abutment with the diaphragm, and the bottom of the pump body is further provided with an inlet one-way valve and an outlet one-way valve respectively. Furthermore, the application also provides a manufacturing method of the micro flow pump. The micro flow pump has the advantages of high response frequency and precise flow control.

Description

Technical Field

[0001] This invention relates to the field of microfluidic pump technology, and in particular to a method for manufacturing a microfluidic pump based on a super magnetostrictive material. Background Technology

[0002] Giant magnetostrictive materials (GMMs) are magnetostrictive materials with an extremely high magnetostriction coefficient. At room temperature, their length and volume change significantly due to changes in their magnetization state. These materials exhibit high heat resistance, strong magnetostrictive properties, high energy-to-mechanical energy conversion rate at room temperature, high energy density, fast response speed, good reliability, and simple actuation methods. Currently, most commercially available giant magnetostrictive materials are rare-earth-based, also known as rare-earth giant magnetostrictive materials.

[0003] Microfluidic pumps are one of the most important components in microfluidic systems. They are devices that control the fluid in a microflow control system, enabling the opening and closing of fluid channels and flow control. They are widely used in fields such as micro-fluid transport and precise flow control, including micro-biochemical detection, micro-drug delivery, micro-fuel supply, and biochips. Currently, the most widely researched and applied microfluidic pump driving methods are piezoelectric, electrostatic, and shape memory alloy (GMA) driven pumps. Piezoelectric and electrostatic pumps rely on high voltage, making them difficult to control with conventional circuits. Furthermore, piezoelectric pumps are prone to drift and electric shock, hindering precise control. GMA pumps offer advantages such as good shock resistance and low-voltage control, but their response is limited by the temperature control system, resulting in a lower response frequency. Therefore, a microfluidic pump with a high response frequency and the ability to precisely control flow is needed. Summary of the Invention

[0004] To address the above problems, this invention provides a method for fabricating a microfluidic pump based on a super magnetostrictive material.

[0005] The present invention adopts the following technical solution:

[0006] A microfluidic pump based on a giant magnetostrictive material is disclosed. The microfluidic pump is a coil-embedded type, comprising a hollow pump body, a diaphragm at the top of the pump body, a metal coil inside the pump body, a protective layer surrounding the metal coil, a giant magnetostrictive rod connected to the middle of the metal coil, the giant magnetostrictive rod abutting against the diaphragm, an aluminum electrode at the bottom of the pump body, the aluminum electrode forming an electrical connection with the metal coil, and an inlet check valve and an outlet check valve respectively at the bottom of the pump body.

[0007] Furthermore, the pump body is made of silicon material.

[0008] Furthermore, the protective layer is a silicon dioxide protective layer or a silicon nitride protective layer.

[0009] Furthermore, the film is made of SU8 photoresist.

[0010] A method for fabricating a microfluidic pump based on a super magnetostrictive material includes the following steps:

[0011] S1. After cleaning the surface of the silicon wafer, a silicon nitride layer a is grown on the bottom of the silicon wafer by LPCVD;

[0012] S2. Plasma etching is used to etch the top surface of the silicon wafer to form an inner cavity;

[0013] S3. Aluminum coils are deposited in the inner cavity and on the top surface of the silicon nitride layer a, and the corresponding pattern is etched out by masking.

[0014] S4. A protective layer is grown on the aluminum coil by LPCVD to protect the aluminum coil;

[0015] S5. Repeat steps S3 and S4 to create a multilayer coil, and then use a mask to etch the protective layer around and inside the coil.

[0016] S6. Place the super magnetostrictive rod in the middle of the coil and connect it to the coil;

[0017] S7. The silicon nitride layer a is etched using a mask to create the valve ports of the inlet check valve and the outlet check valve on both sides of the coil, respectively.

[0018] S8. Deposit a sacrificial layer material in the inner cavity, and then perform surface planarization treatment;

[0019] S9. A polymer material layer is spin-coated on top of the silicon wafer and the sacrificial layer to form a film, with the top of the super magnetostrictive rod abutting against the film;

[0020] S10. Expose and develop the top polymer material layer to form a via that can release the sacrificial layer;

[0021] S11. A metal anti-adhesion layer is vapor-deposited at the valve port of the inlet check valve and the valve port of the outlet check valve at the bottom of the silicon nitride layer a.

[0022] S12. A 4 μm thick silicon nitride layer b is grown at the bottom of the silicon nitride layer a by LPCVD.

[0023] S13. Release the sacrificial layer;

[0024] S14. A silicon nitride layer c is grown on top of the polymer material layer by LPCVD to cover the vias on the polymer material layer and form a sealed structure.

[0025] S15. The silicon nitride layer c is etched using a mask, but the via remains sealed.

[0026] S16. Mask etching of the silicon nitride layer b to form a one-way valve structure;

[0027] S17. Using plasma etching, through holes are etched at the bottom of the silicon nitride layer a and the silicon nitride layer b, and aluminum electrodes are deposited to form an electrical connection with the coil.

[0028] Furthermore, the protective layer in step S4 is a silicon nitride protective layer or a silicon dioxide protective layer.

[0029] Furthermore, the polymer material layer in step S9 is SU8 photoresist.

[0030] Furthermore, the metal anti-adhesion layer in step S11 is made of copper.

[0031] Furthermore, the plasma etching described in steps S2 and S17 is ion-assisted plasma etching, which uses XeF2 as the etching gas and Ar as the etching gas. + As bombarding ions.

[0032] Furthermore, the mask etching described in steps S3, S5, S7, S15, and S16 all employs mask plasma etching.

[0033] By adopting the above technical solution, the present invention has the following advantages compared with the prior art:

[0034] The microfluidic pump of this invention has the advantages of high response frequency and precise flow control. Firstly, thanks to the ultrafast response speed of the super magnetostrictive material, its operating frequency can reach 5 × 10⁻⁶. 4 Hz, single pumping volume is 1.3165×10 -5 The flow rate is 39.495 μL / min. Secondly, the microfluidic pump of the present invention can control the flow rate by controlling the operating frequency and the sample volume by controlling the operating time, thereby achieving precise flow control. In addition, the microfluidic pump of the present invention is highly compatible with microfluidic control systems (LOC) and can pump the vast majority of fluids. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the microfluidic pump of the present invention;

[0036] Figure 2 This is a schematic diagram illustrating the working principle of the microfluidic pump of the present invention.

[0037] Figure 3 This is a flowchart of the manufacturing method of the microfluidic pump of the present invention.

[0038] Explanation of reference numerals in the attached figures:

[0039] 1. Pump body; 11. Inner cavity; 2. Diaphragm; 3. Metal coil; 31. Protective layer; 4. Magnetostrictive rod; 5. Aluminum electrode; 6. Inlet check valve; 7. Outlet check valve. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Example 1

[0041] like Figure 1 As shown (the unit of the scale in the figure is μm), a microfluidic pump based on a giant magnetostrictive material is disclosed. The microfluidic pump is a coil-embedded type, comprising a hollow pump body 1, a diaphragm 2 at the top of the pump body 1, a metal coil 3 in the inner cavity 11 of the pump body 1, a protective layer 31 covering the outside of the metal coil 3, a giant magnetostrictive rod 4 connected to the middle of the metal coil 3, the giant magnetostrictive rod 4 abutting against the diaphragm 2, an aluminum electrode 5 at the bottom of the pump body 1, the aluminum electrode 5 forming an electrical connection with the metal coil 3, and an inlet check valve 6 and an outlet check valve 7 respectively at the bottom of the pump body 1.

[0042] The pump body 1 is made of silicon. The protective layer 31 is a silicon dioxide protective layer. The diaphragm 2 is made of SU8 photoresist.

[0043] To better understand the solution of this embodiment, the working principle of the microfluidic pump described above is further explained. Its working principle is as follows: the reciprocating vibration of the diaphragm 2, combined with the opening movement of the one-way valve, forms a directional flow of fluid. In static analysis, the operation of the microfluidic pump is divided into two processes: suction and discharge. For example... Figure 2 As shown in (a), during the suction stroke, the diaphragm 2 deforms outward, the volume of the inner cavity 11 of the pump body 1 increases, the pressure inside the cavity decreases, the valve plate of the inlet check valve 6 opens, and the valve plate of the outlet check valve 7 closes, allowing liquid to enter the pump cavity from the valve port of the inlet check valve 6; Figure 2 As shown in (b), during the scheduling process, the diaphragm 2 returns to its original position, the pressure in the inner cavity 11 increases, the valve plate of the outlet check valve 7 opens, the valve plate of the inlet check valve 6 closes, and the fluid is discharged from the pump cavity from the valve port of the outlet check valve 7, thus completing a complete fluid outflow cycle.

[0044] The microfluidic pump in this embodiment benefits from the ultrafast response speed of the super magnetostrictive material, and the pump's operating frequency can reach 5 × 10⁻⁶. 4 Hz, single pumping volume is 1.3165×10 -5 The flow rate is 39.495 μL / min. The microfluidic pump of this embodiment can achieve precise flow rate control by controlling the operating frequency to control the flow rate and by controlling the operating time to control the sample volume. Furthermore, the microfluidic pump of this embodiment is highly compatible with microfluidic control systems (LOCs) and can pump the vast majority of fluids. Example 2

[0045] like Figure 3 As shown, a method for fabricating a microfluidic pump based on a super magnetostrictive material is described. This method can be used to manufacture the microfluidic pump described in Embodiment 1 above, and specifically includes the following steps:

[0046] S1, such as Figure 3 As shown in Figure a, a 100μm thick silicon wafer is selected. After surface cleaning, a 4μm thick silicon nitride layer is grown on the bottom of the silicon wafer by LPCVD.

[0047] S2, such as Figure 3 As shown in b, plasma etching is used to etch the top surface of the silicon wafer to form an inner cavity;

[0048] S3, such as Figure 3 As shown in c, aluminum coils are deposited on the top surface of the inner cavity and the silicon nitride layer a, and the corresponding pattern is etched out by a mask.

[0049] S4, such as Figure 3 As shown in d, a silicon dioxide protective layer is grown on the aluminum coil by LPCVD to protect the aluminum coil;

[0050] LPCVD is a low-pressure chemical vapor deposition technique used to deposit a uniform dielectric thin film on a substrate surface, which can then be used as a micromechanical structure layer material, sacrificial layer, insulating layer, mask material, etc.

[0051] S5, such as Figure 3 As shown in e, repeat steps S3 and S4 to fabricate a multilayer coil, and then use a mask to etch the silicon dioxide protective layer around and inside the coil.

[0052] S6, such as Figure 3 As shown in f, a super magnetostrictive rod is placed in the middle of the coil and connected to the coil; the super magnetostrictive rod is a cylinder with a radius of 20 μm and a length of 100 μm;

[0053] The super magnetostrictive rod can be manufactured using the LIGA process, which is a MEMS processing technology based on X-ray lithography. The LIGA process mainly includes three steps: X-ray depth synchrotron radiation lithography, electroforming mold making, and injection molding replication.

[0054] S7, such as Figure 3 As shown in g, the silicon nitride layer a is etched using a mask to create the valve ports of the inlet check valve and the outlet check valve on both sides of the coil, respectively.

[0055] S8, such as Figure 3 As shown in h, a sacrificial layer material is deposited in the inner cavity, and then a surface planarization process is performed;

[0056] S9, such as Figure 3 As shown in Figure i, a polymer material layer is spin-coated on top of the silicon wafer and the sacrificial layer to form a film; the polymer material layer is SU8 photoresist; the film is elastic and is used as a deformable membrane for a microfluidic pump. In this embodiment, SU8 photoresist is used as an example, but it can also be replaced with other materials with the same properties as needed.

[0057] S10, such as Figure 3 As shown in j, the top polymer material layer is exposed and developed to form a via that can release the sacrificial layer;

[0058] S11, such as Figure 3 As shown in k, a metal anti-adhesion layer is vapor-deposited at the valve ports of the inlet check valve and the outlet check valve at the bottom of the silicon nitride layer a; the metal anti-adhesion layer is made of copper.

[0059] S12, such as Figure 3 As shown in Figure l, a 4 μm thick silicon nitride layer b is grown at the bottom of the silicon nitride layer a by LPCVD.

[0060] S13, such as Figure 3 As shown in m, release the sacrificial layer;

[0061] S14, such as Figure 3 As shown in n, a silicon nitride layer c is grown on top of the polymer material layer by LPCVD to cover the vias on the polymer material layer and form a sealed structure;

[0062] S15, such as Figure 3 As shown in o, the silicon nitride layer c is etched by a mask, but the via remains sealed.

[0063] S16, as Figure 3 As shown in p, the silicon nitride layer b is etched using a mask to form a one-way valve structure;

[0064] S17, such as Figure 3As shown in q, plasma etching is used to etch through holes at the bottom of the silicon nitride layer a and the silicon nitride layer b, and aluminum electrodes are deposited to form an electrical connection with the coil.

[0065] The plasma etching described in steps S2 and S17 is ion-assisted plasma etching, which uses XeF2 as the etching gas and Ar as the etching gas. + As bombarding ions, the mask etching described in steps S3, S5, S7, S15, and S16 all employ mask plasma etching.

[0066] The above description is merely a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for manufacturing a microfluidic pump based on a magnetostrictive material, wherein the microfluidic pump is a coil-embedded type, the microfluidic pump includes a hollow pump body, a diaphragm is provided at the top of the pump body, a metal coil is provided in the inner cavity of the pump body, the metal coil is wrapped with a protective layer, a magnetostrictive rod is connected to the middle of the metal coil, the magnetostrictive rod abuts against the diaphragm, an aluminum electrode is provided at the bottom of the pump body, the aluminum electrode is electrically connected to the metal coil, and an inlet check valve and an outlet check valve are respectively provided at the bottom of the pump body, characterized in that: Includes the following steps: S1. After cleaning the surface of the silicon wafer, a silicon nitride layer a is grown on the bottom of the silicon wafer by LPCVD; S2. Plasma etching is used to etch the top surface of the silicon wafer to form an inner cavity; S3. Aluminum coils are deposited in the inner cavity and on the top surface of the silicon nitride layer a, and the corresponding pattern is etched out by masking. S4. A protective layer is grown on the aluminum coil by LPCVD to protect the aluminum coil; S5. Repeat steps S3 and S4 to create a multilayer coil, and then use a mask to etch the protective layer around and inside the coil. S6. Place the super magnetostrictive rod in the middle of the coil and connect it to the coil; S7. The silicon nitride layer a is etched using a mask to create the valve ports of the inlet check valve and the outlet check valve on both sides of the coil, respectively. S8. Deposit a sacrificial layer material in the inner cavity, and then perform surface planarization treatment; S9. A polymer material layer is spin-coated on top of the silicon wafer and the sacrificial layer to form a film, with the top of the super magnetostrictive rod abutting against the film; S10. Expose and develop the top polymer material layer to form a via that can release the sacrificial layer; S11. A metal anti-adhesion layer is vapor-deposited at the valve port of the inlet check valve and the valve port of the outlet check valve at the bottom of the silicon nitride layer a. S12. A 4 μm thick silicon nitride layer b is grown at the bottom of the silicon nitride layer a by LPCVD. S13. Release the sacrificial layer; S14. A silicon nitride layer c is grown on top of the polymer material layer by LPCVD to cover the vias on the polymer material layer and form a sealed structure. S15. The silicon nitride layer c is etched using a mask, but the via remains sealed. S16. Mask etching of the silicon nitride layer b to form a one-way valve structure; S17. Using plasma etching, through holes are etched at the bottom of the silicon nitride layer a and the silicon nitride layer b, and aluminum electrodes are deposited to form an electrical connection with the coil. The plasma etching described in steps S2 and S17 is ion-assisted plasma etching, which uses XeF2 as the etching gas and Ar as the etching gas. + As bombarding ions; the metal anti-adhesion layer in step S11 is made of copper; the mask etching in steps S3, S5, S7, S15 and S16 is all done by mask plasma etching; and the polymer material layer in step S9 is SU8 photoresist.

2. The method for fabricating a microfluidic pump based on a giant magnetostrictive material as described in claim 1, characterized in that: The pump body is made of silicon material.

3. The method for fabricating a microfluidic pump based on a giant magnetostrictive material as described in claim 1, characterized in that: The protective layer in step S4 is a silicon nitride protective layer or a silicon dioxide protective layer.

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