Swing type micropump based on flexible diamond film micro-channel and preparation method

Abstract

The invention provides a swing type micropump based on a flexible diamond film micro-channel and a preparation method, and relates to the field of diamond heat dissipation. Comprising the following steps that S1, a flexible diamond piece is selected and cleaned, and the interior of the flexible diamond piece is machined into a micro-channel; s2, the flexible diamond piece is divided along the center line of the flexible diamond piece, so that the flexible diamond piece is divided into two flexible diamond pieces of which the roots are connected; s3, piezoelectric ceramic films are deposited on the upper faces and the lower faces of the two flexible diamond sheets correspondingly; s4, respectively plating interdigital electrodes on the surfaces of the two piezoelectric ceramic films; excitation signals are applied to the interdigital electrodes (3) to enable the piezoelectric ceramic films (2) to vibrate, the two flexible diamond films (1) are driven to vibrate, so that the stirring efficiency is improved, meanwhile, micro-channels in the flexible diamonds quickly conduct heat from a heat source to cooling liquid, and the heat dissipation efficiency can be greatly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of heat dissipation, and in particular to an oscillating micro pump based on flexible diamond film micro-grooves and a preparation method thereof. Background Art

[0002] With the rapid development of microelectromechanical systems (MEMS) and microfluidics, the demand for high-performance micropumps is increasing. Micropumps have a wide range of applications in biomedicine, chemical analysis, environmental monitoring, and other fields, such as drug delivery, cell culture, and liquid sampling and analysis. Traditional micropumps are typically made of silicon-based or polymer materials, but these materials have limitations in terms of mechanical strength, thermal conductivity, and chemical stability. For example, the low Young's modulus of silicon-based materials limits their performance in high-frequency applications, while polymer materials perform poorly in terms of high-temperature resistance and chemical stability.

[0003] In recent years, diamond has gradually attracted attention as a superhard, high thermal conductivity and chemically inert material. The elastic modulus of diamond is as high as 1200GPa, and the thermal conductivity can reach 2000W / m·K, which is much higher than traditional materials. These excellent physical and chemical properties make it an ideal micro pump material. However, single crystal diamond is difficult to process and has high cost, making it difficult to apply on a large scale. In contrast, flexible diamond films (such as nanocrystalline diamond or ultra-nanocrystalline diamond) have both flexibility (bending radius <5mm) and low stress properties, and can be prepared by chemical vapor deposition (CVD) technology while retaining the excellent properties of diamond, making them suitable for heterogeneous material integration. The thermal conductivity of diamond microchannel heat sinks is between 5637.1-11447.2W / (m 2 ·K), which is 37%-73% higher than that of the aluminum microchannel heat sink of the same shape. Correspondingly, when converted into the fluid volume flow rate in the heat sink, the flow demand of the diamond heat sink can be reduced by 40%.

[0004] Piezoelectric materials, which can produce mechanical deformation under the influence of an electric field, are widely used to drive micropumps. Combining piezoelectric materials with flexible diamond films can achieve efficient and high-precision fluid actuation. This combination not only utilizes the high thermal conductivity and mechanical strength of diamond, but also enables precise control of the fluid through the electrical drive of the piezoelectric material. However, integrating piezoelectric materials with flexible diamond films and applying them to the fabrication of micropumps still faces many challenges, including material compatibility, electrode preparation, and fluid channel design.

[0005] Therefore, developing a method for fabricating an efficient and reliable flexible diamond film piezoelectrically driven micropump has important scientific and application value. This invention provides a fabrication method that, through a series of measures, including optimizing material selection, surface treatment, electrode design, and fluid channel structure, achieves high-performance flexible diamond film piezoelectrically driven micropumps. This method not only improves the mechanical performance and thermal stability of the micropump, but also achieves efficient fluid transport through piezoelectric drive, providing a new solution for the development of microelectromechanical systems and microfluidics. Summary of the Invention

[0006] In order to overcome the problems of the prior art, the present invention proposes an oscillating micro pump based on flexible diamond film micro-grooves and a preparation method thereof.

[0007] The present invention provides the following technical solutions:

[0008] The present invention provides an oscillating micropump based on flexible diamond film microgrooves and a preparation method thereof, and relates to the field of diamond heat dissipation. The method comprises the following steps: step S1, selecting and cleaning a flexible diamond sheet, and processing the interior of the flexible diamond sheet into microgrooves; step S2, dividing the flexible diamond sheet along its center line to form two flexible diamond sheets connected at their roots; step S3, depositing piezoelectric ceramic films on the upper and lower surfaces of the two flexible diamond sheets respectively; step S4, plating interdigital electrodes on the surfaces of the two piezoelectric ceramic films respectively; the present invention applies an excitation signal to the interdigital electrodes (3) to vibrate the piezoelectric ceramic film (2), thereby driving the two flexible diamond films (1) to vibrate, thereby increasing stirring efficiency. At the same time, the microgrooves inside the flexible diamond quickly conduct heat from the heat source to the coolant, which can greatly improve heat dissipation efficiency.

[0009] A swing-type micropump based on flexible diamond film micro-grooves and a preparation method thereof, specifically comprising the following steps:

[0010] 1. A swing micropump based on flexible diamond film micro-channels and a preparation method thereof, characterized in that the method comprises the following steps:

[0011] Step S1: Select and clean a flexible diamond sheet, and process the interior of the flexible diamond sheet into micro-grooves.

[0012] S11, prepare a flexible diamond sheet with a length of 3-5 mm, a width of 3-5 mm, and a thickness of 0.01-0.03 mm, and ultrasonically clean it with acetone, anhydrous ethanol, and deionized water for 5 minutes each, and then blow dry it with high-purity nitrogen to remove surface moisture;

[0013] S12, first coating a photoresist on the surface of a flexible diamond substrate, then aligning the substrate with a mask having a micro-groove pattern for exposure and development, and magnetron sputtering a tungsten film in the micro-groove pattern region exposed by the developed flexible diamond substrate to form tungsten stripes;

[0014] S13, placing the flexible diamond substrate with tungsten stripes into the MPCVD chamber for deposition, and performing epitaxial growth in the areas not covered by the tungsten stripes until the sidewalls of the substrate are continuously grown and connected, thereby growing a diamond film with a deposition thickness of 1 μm to 3 μm;

[0015] S14, using the tungsten stripes as a sacrificial layer, and etching the tungsten stripes with a chemical reagent such as boiling nitric acid (HNO3), hydrofluoric acid (HF), or aqua regia, leaving a hollow flexible diamond micro-groove structure, wherein the micro-groove has a length of 1-2 mm and a depth of 1-1.5 μm;

[0016] S15. Introduce liquids of different colors to check the hollowness of the micro-grooves.

[0017] Step S2: Split the flexible diamond sheet along its center line using a laser cutting process to form two flexible diamond sheets connected at their roots.

[0018] Step S3: depositing piezoelectric ceramic films on the upper and lower surfaces of the two flexible diamond sheets respectively.

[0019] S31. Selecting a square flexible diamond film with a flat and smooth surface;

[0020] S32. Deposit a piezoelectric ceramic film on the flexible diamond film using a deposition technique, with a thickness of 0.01-0.04 mm.

[0021] Step S4: Plate interdigital electrodes on the surfaces of the two piezoelectric ceramic films.

[0022] S41. Depositing metal electrodes on the surface of the piezoelectric ceramic layer by electron beam evaporation technology to a thickness of 0.01-0.03 mm, and forming interdigital electrodes by photolithography and reactive ion etching. The electrode materials can be gold (Au), silver (Ag), platinum (Pt), etc.;

[0023] S42. Connect the interdigitated electrodes to an external power source to provide a driving voltage for the piezoelectric ceramic film.

[0024] Furthermore, in step S13 , the shape of the micro-grooves of the flexible diamond film can be designed to be rectangular, circular, arc-shaped, V-shaped, trapezoidal, etc.

[0025] Furthermore, in step S3, the piezoelectric ceramics are made of lead zirconate titanate (PZT) material, etc. During deposition, the substrate temperature is 300-500° C., the target diameter is 50-60 mm, the sputtering power is 100-120 W, and the sputtering time is 90-180 min.

[0026] Furthermore, in step S3, after deposition, the piezoelectric ceramic film is annealed in a nitrogen or argon atmosphere at 700-800 mbar for 30-60 minutes, and then naturally cooled to room temperature.

[0027] Furthermore, in step S3, the length of the piezoelectric ceramic film is 60%-80% of the length of the flexible diamond film, and the width of the piezoelectric ceramic film is 60%-80% of the width of the flexible diamond film.

[0028] Furthermore, in step S4, the pump driving method includes a co-directional swing method and a cross-directional swing method; the co-directional swing method is: applying excitation signals of the same frequency and phase to the two piezoelectric ceramic films, the two flexible diamond films are driven by the piezoelectric ceramic films to vibrate synchronously in the same direction, driving the liquid to enter from the inlet, pass through the flexible diamond micro-grooves, and be discharged from the outlet;

[0029] Furthermore, in step S4, the pump driving method includes a same-direction swinging method and a cross-swinging method; the cross-swinging method is: applying different excitation signals to the two piezoelectric ceramic films, and the two flexible diamond films vibrate asynchronously driven by the piezoelectric ceramic films, driving the liquid to enter from the inlet, pass through the flexible diamond micro-grooves, and then be output from the outlet.

[0030] Furthermore, in step S4, the photolithography technology is used to form interdigital electrodes. First, a layer of photoresist is evenly coated on the surface of the piezoelectric ceramic film, and then the interdigital electrode pattern is projected onto the photoresist through a photolithography machine for exposure. During the exposure process, a chemical reaction will occur in specific areas of the photoresist to form a latent image consistent with the design pattern; the exposed photoresist is developed, and the photoresist in the unexposed or exposed areas is dissolved to form a clear pattern. Subsequently, a hardening film treatment is performed to remove the remaining solvent in the photoresist by high temperature, thereby enhancing its adhesion to the piezoelectric ceramic film and its etching resistance.

[0031] Furthermore, in step S4, the reactive ion etching forms interdigitated electrodes, and the piezoelectric ceramic film processed by the photolithography process is placed in a reactive ion etching device. Under a vacuum environment, a specific reaction gas (such as Cl2, BCl3, CF4, etc.) is introduced, and the gas is excited by a high-frequency electric field to form a plasma. The high-energy ions in the plasma are accelerated under the action of the electric field to bombard the surface of the piezoelectric ceramic film, and at the same time chemically react with the surface material to achieve precise etching of the target material. At this time, the patterned photoresist serves as a mask to protect the unetched area and ensure that the etching process is carried out according to the pattern on the photoresist; after the etching is completed, the photoresist on the surface of the piezoelectric ceramic film needs to be removed, usually by wet stripping, using an organic solvent (such as acetone) or an inorganic solution (such as H2SO4 and H2O2) to dissolve and clean the photoresist, leaving a micro-nano structure etched according to the designed pattern on the piezoelectric ceramic film.

[0032] The key to the implementation of the present invention is:

[0033] (1) Micro-grooves are machined inside the flexible diamond sheet using photolithography and magnetron sputtering to facilitate the flow of liquids.

[0034] (2) Use a cracking tool to split a flexible diamond sheet along its center line to form two flexible diamond sheets connected at the roots.

[0035] (3) A piezoelectric ceramic film is deposited on the flexible diamond film, and interdigital electrodes are plated on the surface of the piezoelectric ceramic layer.

[0036] (4) Applying an excitation signal to the two piezoelectric ceramic films, the two flexible diamond films vibrate in the same direction or crosswise under the drive of the piezoelectric ceramic films, thereby improving the heat dissipation efficiency.

[0037] The beneficial effects brought about by the technical solution provided by the present invention include at least:

[0038] (1) The flexible diamond film as a substrate can efficiently dissipate heat, avoid thermal failure, and increase the life of the micropump by more than 3 times under high-frequency drive.

[0039] (2) Through the composite vibration amplification mechanism of piezoelectric ceramics and diamond, the vibration efficiency is improved, the stirring rate is increased, and the heat dissipation efficiency is improved.

[0040] (3) Diamond micro-grooves are used to quickly transfer heat from the heat source to the coolant, improving heat dissipation performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 A flow chart for preparing the micropump provided by the present invention;

[0043] Figure 2 A schematic diagram of the micro pump structure provided by the present invention;

[0044] Figure 3 A schematic diagram of the structure of the interdigital electrode-piezoelectric ceramic film-flexible diamond film provided by the present invention;

[0045] Figure 4 A perspective schematic diagram of the micropump provided by the present invention;

[0046] Figure 5 A schematic diagram of the micro-pump swing structure provided by the present invention;

[0047] Explanation of the accompanying figures: 1-flexible diamond film, 2-piezoelectric ceramic film, 3-interdigitated electrode. DETAILED DESCRIPTION

[0048] In order to make the purpose, technical solutions and advantages of the present invention more clear, the technical solutions of the present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] Example 1

[0050] The present invention uses an oscillating micropump based on flexible diamond film microgrooves. A flexible diamond sheet with a length of 4 mm, a width of 4 mm, and a thickness of 0.02 mm is prepared. The sheet is ultrasonically cleaned with acetone, anhydrous ethanol, and deionized water for 5 minutes each, and then blown dry with high-purity nitrogen to remove surface moisture. A photoresist is first coated on the surface of the flexible diamond substrate, and then the sheet is aligned with a mask having a microgroove pattern for exposure and development. A tungsten film is magnetron sputtered on the microgroove pattern area exposed by the developed flexible diamond substrate to form tungsten stripes. The flexible diamond substrate with tungsten stripes is placed in an MPCVD chamber for deposition, and epitaxial growth is performed on the area not covered by the tungsten stripes. The process involved growing the tungsten stripes until the substrate sidewalls connected and formed a 2μm thick diamond film. The tungsten stripes were etched using chemical reagents such as nitric acid (HNO3) and hydrofluoric acid (HF), ultimately forming flexible diamond microgrooves with a hollow structure. The microgrooves were 1.5mm long and 1.5μm deep. Different colored liquids were introduced to inspect the hollowness of the microgrooves. The flexible diamond sheet was laser cut along its centerline to form two connected flexible diamond sheets. A 0.03mm thick piezoelectric ceramic film was deposited on the top and bottom of each flexible diamond sheet. Interdigitated electrodes were then plated on the surfaces of the two piezoelectric ceramic films. These electrodes were then connected to an external power source to provide a driving voltage for the lead zirconate titanate material. The pump driving method includes a co-directional swing method and a cross-directional swing method; excitation signals of the same frequency and phase or different excitation signals are applied to two piezoelectric ceramic films, and the two flexible diamond films are driven by the piezoelectric ceramic films to vibrate synchronously or asynchronously in the same direction, driving the liquid to enter from the inlet, pass through the flexible diamond micro-grooves, and be discharged from the outlet.

[0051] Comparative Example

[0052] An oscillating micropump with flexible diamond film microgrooves was prepared using the same process as in Example 1, with only the piezoelectric ceramic film deposition thickness changed to 0.005 mm. The results showed that the piezoelectric ceramic film could not drive the flexible diamond sheet to vibrate. The piezoelectric ceramic film produced slight deformation under the action of the electric field, which could not be effectively transmitted to the flexible diamond sheet, resulting in a significant decrease in the stirring rate and heat dissipation efficiency of the flexible diamond sheet.

Claims

1. A swing micro pump based on flexible diamond film micro-channels and a preparation method thereof, characterized in that: The following steps are involved: Step S1: Select and clean a flexible diamond sheet, and process the interior of the flexible diamond sheet into micro-grooves. S11, prepare a flexible diamond sheet with a length of 3-5 mm, a width of 3-5 mm, and a thickness of 0.01-0.03 mm, and ultrasonically clean it with acetone, anhydrous ethanol, and deionized water for 5 minutes each, and then blow dry it with high-purity nitrogen to remove surface moisture; S12, first coating a photoresist on the surface of a flexible diamond substrate, then aligning the substrate with a mask having a micro-groove pattern for exposure and development, and magnetron sputtering a tungsten film in the micro-groove pattern region exposed by the developed flexible diamond substrate to form tungsten stripes; S13, placing the flexible diamond substrate with tungsten stripes into an MPCVD chamber for deposition, and performing epitaxial growth in the area not covered by the tungsten stripes until the sidewalls of the substrate are continuously grown and connected, thereby growing a diamond film with a deposition thickness of 1 μm to 3 μm; S14, etching the tungsten stripes with chemical reagents such as nitric acid (HNO3) and hydrofluoric acid (HF), ultimately forming flexible diamond microgrooves with a hollow structure, the length of the microgrooves being 1-2 mm and the depth being 1-1.5 μm; S15. Introduce liquids of different colors to check the hollowness of the micro-grooves. Step S2: Split the flexible diamond sheet along its center line using a laser cutting process to form two flexible diamond sheets connected at their roots. Step S3: depositing piezoelectric ceramic films on the upper and lower surfaces of the two flexible diamond sheets respectively. S31. Selecting a square flexible diamond film with a flat and smooth surface; S32. Deposit a piezoelectric ceramic film on the flexible diamond film using a deposition technique, with a thickness of 0.01-0.04 mm. Step S4: Plate interdigital electrodes on the surfaces of the two piezoelectric ceramic films. S41. Depositing metal electrodes on the surface of the piezoelectric ceramic layer by electron beam evaporation technology to a thickness of 0.01-0.03 mm, and forming interdigital electrodes by photolithography and reactive ion etching. The electrode materials can be gold (Au), silver (Ag), platinum (Pt), etc.; S42. Connect the interdigitated electrodes to an external power source to provide a driving voltage for the piezoelectric ceramic film.

2. The method according to claim 1, characterized in that In step S13 , the shape of the micro-grooves of the flexible diamond film can be designed to be rectangular, circular, arc-shaped, V-shaped, trapezoidal, etc.

3. The method according to claim 1, characterized in that In step S3, the piezoelectric ceramics are made of lead zirconate titanate (PZT) material, etc. During deposition, the substrate temperature is 300-500°C, the target diameter is 50-60mm, the sputtering power is 100-120W, and the sputtering time is 90-180min.

4. The method according to claim 1, wherein In step S3 , after deposition, the piezoelectric ceramic film is annealed in a nitrogen or argon atmosphere at 700-800 mbar for 30-60 minutes, and then naturally cooled to room temperature.

5. The method according to claim 1, characterized in that In step S3, the length of the piezoelectric ceramic film is 60%-80% of the length of the flexible diamond film, and the width of the piezoelectric ceramic film is 60%-80% of the width of the flexible diamond film.

6. The method according to claim 1, characterized in that In step S4, the pump driving method includes a same-direction swing method and a cross-swing method; the same-direction swing method is: applying excitation signals of the same frequency and phase to the two piezoelectric ceramic films, and the two flexible diamond films vibrate synchronously in the same direction under the drive of the piezoelectric ceramic films, driving the liquid to enter from the inlet, pass through the flexible diamond micro-grooves, and be output from the outlet.

7. The method according to claim 1, characterized in that In step S4, the pump driving method includes a co-directional swing method and a cross-swing method; the cross-swing method is: different excitation signals are applied to the two piezoelectric ceramic films, and the two flexible diamond films vibrate asynchronously under the drive of the piezoelectric ceramic films, driving the liquid to enter from the inlet, pass through the flexible diamond micro-grooves, and then be output from the outlet.

8. The method according to claim 1, characterized in that In step S4, the photolithography technology is used to form interdigital electrodes. First, a layer of photoresist is evenly coated on the surface of the piezoelectric ceramic film, and the designed pattern is exposed and then hardened.

9. The method according to claim 1, characterized in that In step S4, the reactive ion etching is performed to form interdigitated electrodes. The piezoelectric ceramic film processed by the photolithography process is placed in a reactive ion etching device, and high-energy ions are accelerated to bombard the surface of the piezoelectric ceramic film to achieve precise etching.

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