A MEMS piezoelectric micropump and a preparation method thereof

Abstract

A MEMS piezoelectric micropump and its fabrication method are disclosed. The MEMS piezoelectric micropump includes a substrate; a plurality of first liquid storage cavities located within the substrate; a first piezoelectric driving unit located on a first surface of the substrate and covering the plurality of first liquid storage cavities, the first piezoelectric driving unit being used to drive unidirectional flow of fluid within the plurality of first liquid storage cavities; a plurality of second liquid storage cavities located within the substrate, the first liquid storage cavities and the second liquid storage cavities being arranged alternately, and adjacent first liquid storage cavities and second liquid storage cavities being connected in series through a first conical through-hole or a second conical through-hole; and a second piezoelectric driving unit located on a second surface of the substrate and covering the second liquid storage cavities, being used to drive unidirectional flow of fluid within the plurality of second liquid storage cavities. This invention improves the stability and fluid delivery accuracy of the MEMS micropump by forming a valveless microchannel with unidirectional flow through the series connection of the first liquid storage cavities and the second liquid storage cavities.

Description

Technical Field

[0001] This invention relates to the field of microfluidic pump technology, specifically to a MEMS piezoelectric micropump and its fabrication method. Background Technology

[0002] Microfluidics refers to the science and technology of manipulating microfluidics within micrometer-scale structures. Microelectromechanical systems (MEMS) micropumps, as core driving components in microfluidic systems, enable precise control of fluids at the nanoliter to microliter level. With the widespread application of microfluidics in integrated circuit heat dissipation and biochemistry, in integrated circuit heat dissipation, third-generation semiconductor devices (such as GaN and SiC) generate enormous heat due to their high power density, and the performance of existing MEMS micropumps is insufficient to meet their efficient heat dissipation requirements. In biochemistry, microfluidics technology requires controlled directional and quantitative delivery of liquids in processes such as cell transport, chemical detection, drug delivery, and molecular recognition, which places higher demands on the stability and fluid delivery accuracy of MEMS micropumps. Summary of the Invention

[0003] The technical problem solved by this invention is to provide a MEMS piezoelectric micropump and its fabrication method, which improves the stability and fluid delivery accuracy of the MEMS micropump by forming a valveless microchannel with unidirectional flow through a first cavity and a second cavity connected in series.

[0004] To address the aforementioned technical problems, this invention provides a MEMS piezoelectric micropump, comprising: a substrate, the substrate including opposing first and second surfaces; a plurality of first liquid storage cavities located within the substrate, each first liquid storage cavity including a first opening extending from the first surface into the substrate and a first tapered through-hole located within the first opening, the diameter of the first tapered through-hole gradually decreasing from the first opening towards the second surface; a first piezoelectric driving unit located on the first surface and covering the plurality of first liquid storage cavities, the first piezoelectric driving unit being used to drive unidirectional flow of fluid within the plurality of first liquid storage cavities; and a plurality of second liquid storage cavities located within the substrate, each second liquid storage cavity including a second opening extending from the second surface into the substrate and a second tapered through-hole located within the second opening. The aperture of the second conical through-hole gradually decreases from the second opening towards the first surface; wherein the first liquid storage cavity and the second liquid storage cavity are arranged alternately, the first conical through-hole of the first liquid storage cavity is connected to the second opening of the corresponding second liquid storage cavity, and the second conical through-hole of the second liquid storage cavity is connected to the first opening of the corresponding first liquid storage cavity, so that adjacent first liquid storage cavities and second liquid storage cavities are connected in series through the first conical through-hole or the second conical through-hole; a second piezoelectric driving unit is located on the second surface and covers the second liquid storage cavity, the second piezoelectric driving unit is used to drive the fluid in the plurality of second liquid storage cavities to flow unidirectionally, and the flow direction of the fluid in the plurality of first liquid storage cavities is consistent with the flow direction of the fluid in the plurality of second liquid storage cavities.

[0005] Optionally, the cone angle of the first tapered through hole is 55° to 70°, and the cone angle of the second tapered through hole is 55° to 70°.

[0006] Optionally, the first piezoelectric driving unit includes a first vibration diaphragm, a first piezoelectric film, and a first driving electrode formed sequentially from the first surface, with the first driving electrode corresponding to the position of the first liquid storage cavity; the second piezoelectric driving unit includes a second vibration diaphragm, a second piezoelectric film, and a second driving electrode formed sequentially from the second surface, with the second driving electrode corresponding to the position of the second liquid storage cavity.

[0007] Optionally, both the first driving electrode and the second driving electrode are interdigitated electrodes, and the fingers of the interdigitated electrodes are arranged along the arrangement direction of the first liquid storage cavity and the second liquid storage cavity.

[0008] Optionally, the fluid in the first liquid storage cavity flows unidirectionally from the first opening to the first conical through hole; the fluid in the second liquid storage cavity flows unidirectionally from the second opening to the second conical through hole.

[0009] Optionally, it also includes: an inlet connected to the first of a plurality of alternating first and second liquid storage cavities; and an outlet connected to the last of a plurality of alternating first and second liquid storage cavities.

[0010] Accordingly, the present invention also provides a method for fabricating a MEMS piezoelectric micropump, comprising: providing a substrate, the substrate including opposing first surfaces and second surfaces; forming a plurality of first liquid storage cavities within the substrate, each first liquid storage cavity including a first opening extending from the first surface into the substrate and a first conical through-hole located within the first opening, wherein the diameter of the first conical through-hole gradually decreases from the first opening towards the second surface; forming a first sacrificial layer within the plurality of first liquid storage cavities; forming a first piezoelectric driving unit on the surface of the first sacrificial layer, the first piezoelectric driving unit being used to drive unidirectional flow of fluid within the first liquid storage cavity; forming a plurality of second liquid storage cavities within the substrate, each second liquid storage cavity including a second opening extending from the second surface into the substrate and a second conical through-hole located within the second opening, wherein the diameter of the second conical through-hole gradually decreases from the first opening towards the second surface; forming a first sacrificial layer within the plurality of first liquid storage cavities; forming a first piezoelectric driving unit on the surface of the first sacrificial layer, the first piezoelectric driving unit being used to drive unidirectional flow of fluid within the first liquid storage cavity; and forming a plurality of second liquid storage cavities within the substrate, each second liquid storage cavity including a second opening extending from the second surface into the substrate and a second conical through-hole located within the second opening, wherein the diameter of the second conical through-hole gradually decreases from the first opening towards the second surface; forming a first sacrificial layer within the plurality of first liquid storage cavities; forming a first piezoelectric driving unit on the surface of the first sacrificial layer ... The aperture of the hole gradually decreases from the second opening towards the first surface; wherein, the first liquid storage cavity and the second liquid storage cavity are arranged alternately, the first conical through hole of the first liquid storage cavity is connected to the second opening of the corresponding second liquid storage cavity, and the second conical through hole of the second liquid storage cavity is connected to the first opening of the corresponding first liquid storage cavity, so that adjacent first liquid storage cavities and second liquid storage cavities are connected in series through the first conical through hole or the second conical through hole; a second sacrificial layer is formed in the plurality of second liquid storage cavities; a second piezoelectric driving unit is formed on the surface of the second sacrificial layer, the second piezoelectric driving unit is used to drive the fluid in the plurality of second liquid storage cavities to flow unidirectionally, the flow direction of the fluid in the plurality of first liquid storage cavities is consistent with the flow direction of the fluid in the plurality of second liquid storage cavities; the first sacrificial layer and the second sacrificial layer are removed.

[0011] Optionally, the process for forming the first tapered via and the second tapered via includes deep reactive ion etching.

[0012] Optionally, the method for forming the first piezoelectric drive unit includes: sequentially forming a first vibration diaphragm, a first piezoelectric thin film, and a first drive electrode material layer on the first surface and the first sacrificial layer; and performing patterning processing on the first drive electrode material layer to form a first drive electrode corresponding to the position of the first liquid storage cavity; the method for forming the second piezoelectric drive unit includes: sequentially forming a second vibration diaphragm, a second piezoelectric thin film, and a second drive electrode material layer on the second surface and the second sacrificial layer; and performing patterning processing on the second drive electrode material layer to form a second drive electrode corresponding to the position of the second liquid storage cavity.

[0013] Optionally, during the formation of a plurality of first liquid storage cavities and a plurality of second liquid storage cavities, the first opening of the first liquid storage cavity in the plurality of alternating first liquid storage cavities and second liquid storage cavities penetrates the sidewall of the substrate to form an inlet, and the second opening of the last second liquid storage cavity in the plurality of alternating first liquid storage cavities and second liquid storage cavities penetrates the sidewall of the substrate to form an outlet.

[0014] Compared with the prior art, the technical solution of the present invention has the following beneficial effects: The MEMS piezoelectric micropump provided by this invention includes a plurality of first liquid storage cavities formed inward on a first surface of a substrate and a plurality of second liquid storage cavities formed inward on a second surface of the substrate. Each first liquid storage cavity includes a first opening extending from the first surface into the substrate and a first conical through-hole located within the first opening. Each second liquid storage cavity includes a second opening extending from the second surface into the substrate and a second conical through-hole located within the second opening. Since the diameter of the first conical through-hole gradually decreases from the first opening towards the second surface, for the first liquid storage cavity, the connection between the first conical through-hole and the first opening is designed as an expansion-contraction channel, thereby enabling unidirectional flow of fluid within the channel of the first liquid storage cavity, i.e., the fluid flows towards the smaller diameter of the first conical through-hole. Similarly, the connection between the second conical through-hole and the second opening is also designed as an expansion-contraction channel, thereby enabling unidirectional flow of fluid within the channel of the second liquid storage cavity, i.e., the fluid flows towards the smaller diameter of the second conical through-hole. Furthermore, since the first and second liquid storage cavities are arranged alternately, the first conical through-hole of the first liquid storage cavity is connected to the second opening of the corresponding second liquid storage cavity, and the second conical through-hole of the second liquid storage cavity is connected to the first opening of the corresponding first liquid storage cavity. This allows adjacent first and second liquid storage cavities to be connected in series through the first or second conical through-hole. Therefore, a channel structure is formed by several alternating first and second liquid storage cavities. This structure itself constitutes a microchannel with unidirectional flow, which completely eliminates the valve fatigue problem. At the same time, the series connection of multiple liquid storage cavities realizes the flow rate of the microchannel, further improving the stability of the MEMS piezoelectric micropump. Furthermore, by using a first piezoelectric drive unit / second piezoelectric drive unit to drive the unidirectional flow of fluid within several first liquid storage chambers / several second liquid storage chambers, the unidirectional flow rate is further increased based on the inherent unidirectional flowability of the microchannel structure. Moreover, the combined action of the first and second piezoelectric drive units significantly enhances the instantaneous velocity and average flow rate of the fluid within the microchannel. Combined with the unidirectional flow characteristics of the microchannel, high-pressure unidirectional fluid pumping is achieved under low-voltage drive. Therefore, the valveless microchannel with unidirectional flowability formed by alternating series of several first and second liquid storage chambers can significantly improve the stability of the MEMS micropump. Furthermore, the performance and fluid delivery accuracy of the MEMS micropump are further improved by combining the first and second piezoelectric drive units.

[0015] The method for fabricating a MEMS piezoelectric micropump provided by the technical solution of the present invention is used to fabricate the above-mentioned MEMS piezoelectric micropump, and therefore also has the technical effects of the above-mentioned MEMS piezoelectric micropump, which will not be repeated here. Attached Figure Description

[0016] Figures 1 to 13This is a schematic diagram of the structure of each step in the fabrication method of a MEMS piezoelectric micropump according to an embodiment of the present invention.

[0017] Explanation of reference numerals in the attached figures: 100. Substrate; 101. First surface; 102. Second surface; 200, First opening; 300, First tapered through-hole; 400, Second opening; 500, Second tapered through-hole; 610, First sacrificial layer; 611, Second sacrificial layer; 620, First vibration diaphragm; 621, Second vibration diaphragm; 630, First piezoelectric film; 631, Second piezoelectric film; 640, First driving electrode; 641, Second driving electrode; 700, imports; 800, exports. Detailed Implementation

[0018] As mentioned in the background, the performance, stability, and accuracy of existing MEMS micropumps are insufficient to meet the requirements of applications in integrated circuit heat dissipation and biochemistry. Specifically, valve micropumps (such as solenoid valves or diaphragm valves) suffer from valve body fatigue failure due to long-term vibration, resulting in decreased pumping efficiency and poor stability. This is especially problematic in biomedical devices, where it can easily cause intermittent interruptions in cell delivery, severely impacting system reliability. Single-chamber valveless piezoelectric micropumps, while avoiding valve body fatigue failure, have insufficient flow rate (<50 μL / min) and pressure (<10 kPa) performance, making it difficult to meet the high-efficiency heat dissipation requirements of third-generation semiconductor devices. 3D-printed pump bodies (such as PLA, ABS plastic, PMMA plexiglass, or ceramic powder) can achieve complex structures, but 3D-printed pump bodies have weak interlayer bonding, large size, high cost, difficult integration, and low yield, making them unsuitable for large-scale applications.

[0019] To address the aforementioned technical problems, the present invention provides a MEMS piezoelectric micropump and its fabrication method. By using a valveless microchannel with unidirectional flow formed by connecting a first cavity and a second cavity in series, the stability and fluid delivery accuracy of the MEMS micropump are improved.

[0020] To make the above-mentioned objectives, features, and beneficial effects of the present invention more apparent and understandable, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0021] The terms “first,” “second,” “third,” “fourth,” etc. (if present) in the specification, claims, and drawings of this invention are used to distinguish similar objects and are not necessarily used to describe a particular order or sequence. It should be understood that such data can be interchanged where appropriate so that embodiments of the invention described herein can be implemented in orders other than those illustrated or described herein. Furthermore, the terms “comprising” and “having,” and any variations thereof, are intended to cover a non-exclusive inclusion; for example, a process, method, system, product, or apparatus that comprises a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such processes, methods, products, or apparatus. Additionally, directional terms such as above, below, up, down, upward, downward, left, right, etc., are used relative to exemplary embodiments as they are shown in the figures, with upward or upper directions pointing towards the top of the corresponding figure and downward or lower directions pointing towards the bottom of the corresponding figure.

[0022] Figures 1 to 13 This is a schematic diagram of the structure of each step in the fabrication method of a MEMS piezoelectric micropump according to an embodiment of the present invention.

[0023] Please refer to Figure 1 Substrate 100 is provided.

[0024] In this embodiment, the substrate 100 may include a first surface 101 and a second surface 102 opposite to each other.

[0025] Specifically, the substrate 100 can be, for example, a silicon substrate; of course, it can also be other types of substrates, and the present invention does not limit this. The size of the substrate 100 can be, for example, 6 inches, 8 inches, 12 inches, etc., and is not limited thereto.

[0026] Please refer to the reference. Figures 2 to 3 Several first liquid storage cavities are formed within the substrate 100.

[0027] Each first liquid storage cavity may include a first opening 200 extending from the first surface 101 into the substrate 100 and a first tapered through hole 300 located within the first opening 200.

[0028] For details, please refer to Figure 2 A first opening 200 is formed within the substrate 100.

[0029] In this embodiment, the first opening 200 faces the first surface 101.

[0030] In this embodiment, the first opening 200 has a lateral dimension parallel to the surface of the substrate 100 that is greater than its depth dimension perpendicular to the surface of the substrate 100.

[0031] Please refer to Figure 3 A first conical through hole 300 is formed within the first opening 200.

[0032] In this embodiment, the first tapered through hole 300 can penetrate the first opening 200 and the second surface 102 of the substrate 100, and the aperture of the first tapered through hole 300 gradually decreases from the first opening 200 to the second surface 102.

[0033] In this embodiment, the cone angle of the first tapered through hole 300 is 55° to 70°.

[0034] Specifically, the cone angle can be understood as the angle between the two generatrices of the axial section of a cone (the plane passing through the cone's axis).

[0035] Specifically, the process for forming the first opening 200 may include etching, for example; the process for forming the first tapered via 300 may include deep reactive ion etching (DRIE), for example. Of course, it should be understood that the present invention is not limited thereto, and other feasible processes are also within the scope of protection of the present invention.

[0036] Specifically, the cone angle of the first tapered through-hole 300 can be controlled by adjusting the mask opening size and the etching time gradient.

[0037] In this embodiment, the first tapered through-hole 300 penetrates the substrate 100 to form a through-hole, which can serve as a positioning mark and facilitates the subsequent formation of the second liquid storage cavity.

[0038] In another embodiment, the first tapered through-hole 300 does not penetrate the substrate 100, and a substrate material of a predetermined thickness is left between the bottom surface of the first tapered through-hole 300 and the second surface 102 of the substrate 100. The predetermined thickness can be less than or equal to the depth of the second opening of the second liquid storage cavity to be formed subsequently.

[0039] Please refer to Figure 4 A first sacrificial layer 610 is formed within several first liquid storage cavities.

[0040] Specifically, the material of the first sacrificial layer 610 may include, for example, SiO2 or Si3N4.

[0041] Specifically, the process of forming the first sacrificial layer 610 may include, for example, chemical mechanical polishing (CMP) to make the surface of the first sacrificial layer 610 flush with the first surface 101.

[0042] Please refer to the reference. Figures 5 to 7 A first piezoelectric drive unit is formed on the surface of the first sacrificial layer 610, wherein the first piezoelectric drive unit is used to drive the fluid in the first liquid storage cavity to flow in one direction.

[0043] Specifically, the fluid in the first liquid storage chamber flows in one direction from the first opening to the first conical through hole.

[0044] In this embodiment, the first piezoelectric drive unit may include a first vibration diaphragm 620, a first piezoelectric film 630 and a first drive electrode 640 sequentially formed from the first surface 101.

[0045] Please refer to Figure 5 A first vibration diaphragm 620 is formed on the surface of the first sacrificial layer 610 and the first surface 101.

[0046] Specifically, the material of the first vibration diaphragm 620 may include, for example, any one of Si3N4, Si, and polycrystalline silicon or a polymer.

[0047] Specifically, the thickness of the first vibration diaphragm 620 can be, for example, 0.5 μm to 5 μm.

[0048] Please refer to Figure 6 A first piezoelectric film 630 is formed on the surface of the first vibration diaphragm 620.

[0049] Specifically, the material of the first piezoelectric thin film 630 may include, for example, at least one of lead zirconium titanate (PZT) and AlN.

[0050] Specifically, the thickness of the first piezoelectric thin film 630 can be, for example, 10 μm to 30 μm.

[0051] Please refer to Figure 7 A first driving electrode 640 is formed on the surface of the first piezoelectric film 630.

[0052] The first driving electrode 640 is positioned corresponding to the first liquid storage cavity.

[0053] Specifically, the projection of the first driving electrode 640 on the first surface 101 is at least located within the projection of the first liquid storage cavity on the first surface 101.

[0054] Specifically, the first driving electrode 640 drives the first piezoelectric film 630 to deform along a first direction, which is located in the plane where the first piezoelectric film 630 is located.

[0055] Specifically, the method for forming the first driving electrode 640 may include: forming a first driving electrode material layer (not shown) on the surface of the first piezoelectric film 630, performing patterning processing on the first driving electrode material layer, and forming the first driving electrode 640 corresponding to the position of the first liquid storage cavity.

[0056] Please refer to the reference. Figures 8 to 9 Several second liquid storage cavities are formed within the substrate 100.

[0057] Each of the second liquid storage cavities may include a second opening 400 extending from the second surface 102 into the substrate 100 and a second tapered through hole 500 located within the second opening 400.

[0058] Please refer to Figure 8 A second opening 400, independent of the first opening 200, is formed within the substrate 100.

[0059] Specifically, the projection of the first opening 200 onto the surface of the substrate 100 at least partially overlaps with the projection of the adjacent second opening 400 onto the surface of the substrate 100.

[0060] In this embodiment, before forming the second opening 400, the substrate 100 may be flipped so that the second surface 102 is a processable surface.

[0061] Please refer to Figure 9 A second conical through hole 500 is formed within the second opening 400.

[0062] The second tapered through-hole 500 can penetrate the second opening 400 and the first surface 101 of the substrate 100, and the diameter of the second tapered through-hole 500 gradually decreases from the second opening 400 to the first surface 101.

[0063] Specifically, the second tapered through-hole 500 penetrates the substrate between the second opening 400 and the first opening 200.

[0064] In this embodiment, reference continues to be made to Figure 8 and Figure 9 The projections of the second opening 400 and the two adjacent first openings 200 at least partially overlap. One end of the second opening 400 is connected to an adjacent first opening 200 through a first tapered through-hole 500. The other end of the second opening 400 is connected to another adjacent first opening 200 through a second tapered through-hole 500.

[0065] Specifically, the cone angle of the second conical through hole 500 is 55° to 70°.

[0066] Specifically, the process for forming the second tapered through hole 500 can be the same as the process for forming the first tapered through hole 300.

[0067] Please continue to refer to this. Figure 9 The first liquid storage chamber and the second liquid storage chamber are arranged alternately, and adjacent first liquid storage chambers and second liquid storage chambers are connected in series through a first conical through hole 300 or a second conical through hole 500.

[0068] In this embodiment, the first conical through hole 300 of the first liquid storage cavity is connected to the second opening 400 of the corresponding second liquid storage cavity, and the second conical through hole 500 of the second liquid storage cavity is connected to the first opening 200 of the corresponding first liquid storage cavity, so that adjacent first liquid storage cavities and second liquid storage cavities are connected in series through the first conical through hole 300 or the second conical through hole 500.

[0069] Specifically, between adjacent first and second liquid storage cavities, the first tapered through-hole 300 and the corresponding second opening 400 can be understood as the projection of the first tapered through-hole 300 on the surface of substrate 100 being within the projection range of the second opening 400 on the surface of substrate 100, and the second tapered through-hole 500 and the corresponding first opening 200 can be understood as the projection of the second tapered through-hole 500 on the surface of substrate 100 being within the projection range of the first opening 200 on the surface of substrate 100.

[0070] Please continue to refer to this. Figure 9 This resulted in imports of 700 and exports of 800.

[0071] In this embodiment, the inlet 700 is connected to the first of several alternating first and second liquid storage chambers.

[0072] In this embodiment, the outlet 800 is connected to the last of a plurality of alternating first and second liquid storage cavities.

[0073] Specifically, the method for forming the inlet 700 and the outlet 800 may include: during the process of forming a plurality of first liquid storage cavities and a plurality of second liquid storage cavities, the first opening 200 of the first liquid storage cavity in the plurality of alternating first liquid storage cavities and second liquid storage cavities penetrates the sidewall of the substrate 100 to form the inlet 700, and the second opening 400 of the last second liquid storage cavity in the plurality of alternating first liquid storage cavities and second liquid storage cavities penetrates the sidewall of the substrate 100 to form the outlet 800.

[0074] Please refer to Figure 10 A second sacrificial layer 611 is formed within several second liquid storage cavities.

[0075] Specifically, the material of the second sacrificial layer 611 can be the same as the material of the first sacrificial layer 610.

[0076] Specifically, the process of forming the second sacrificial layer 611 may include chemical mechanical polishing (CMP) to make the surface of the second sacrificial layer 611 flush with the second surface 102.

[0077] Please refer to the reference. Figures 11 to 12A second piezoelectric driving unit is formed on the surface of the second sacrificial layer 611. The second piezoelectric driving unit is used to drive the fluid in the several second liquid storage cavities to flow unidirectionally. The flow direction of the fluid in the several first liquid storage cavities is consistent with the flow direction of the fluid in the several second liquid storage cavities.

[0078] Specifically, the fluid in the second liquid storage chamber flows in one direction from the second opening 400 to the second conical through hole 500.

[0079] Specifically, the second piezoelectric drive unit may include a second vibration diaphragm 621, a second piezoelectric thin film 631, and a second drive electrode 641 sequentially formed from the second surface 102.

[0080] Please refer to Figure 11 A second vibration diaphragm 621 and a second piezoelectric film 631 are sequentially formed on the second surface 102.

[0081] Specifically, the material and thickness of the second vibration diaphragm 621 can be the same as those of the first vibration diaphragm 620.

[0082] Specifically, the material and thickness of the second piezoelectric film 631 can be the same as those of the first piezoelectric film 630.

[0083] Please refer to Figure 12 A second driving electrode 641 is formed on the surface of the second piezoelectric film 631.

[0084] The second driving electrode 641 is positioned corresponding to the second liquid storage cavity.

[0085] Specifically, the projection of the second driving electrode 641 on the second surface 102 is at least located within the projection of the second liquid storage cavity on the second surface 102.

[0086] Specifically, the second driving electrode 641 drives the second piezoelectric film 631 to deform along a second direction, which is located in the plane where the second piezoelectric film 631 is located.

[0087] Specifically, the method for forming the second driving electrode 641 may include: forming a second driving electrode material layer (not shown) on the surface of the second piezoelectric film 631, and performing patterning processing on the second driving electrode material layer to form a second driving electrode 641 corresponding to the position of the second liquid storage cavity.

[0088] Specifically, both the first driving electrode 640 and the second driving electrode 641 can be interdigitated electrodes, with the fingers of the interdigitated electrodes arranged along the series direction of the first liquid storage cavity and the second liquid storage cavity.

[0089] Specifically, the thickness of the interdigitated electrode layer can be 0.3 μm to 1 μm.

[0090] Specifically, the material of the interdigitated electrode can be at least one of Al, Mo, and Cu.

[0091] In this embodiment, both the first driving electrode 640 and the second driving electrode 641 are in d33 mode. At low voltage (10V–20V), they can excite high-amplitude vibrations in the piezoelectric film and the vibrating diaphragm, thereby significantly increasing the instantaneous velocity and average flow rate of the fluid in the microchannel. Combined with the unidirectional flow characteristics of the microchannel, high-pressure unidirectional fluid pumping is achieved under low-voltage driving. Furthermore, the d33 mode driving electrode has a millisecond-level response speed. By controlling the driving frequency, the MEMS micropump can achieve fluid delivery with minimal increments.

[0092] Please refer to Figure 13 Remove the first sacrificial layer 610 and the second sacrificial layer 611.

[0093] Specifically, the process for removing the first sacrificial layer 610 and the second sacrificial layer 611 may include wet etching.

[0094] In this embodiment, the first sacrificial layer 610 is removed to release the first liquid storage cavity, and the second sacrificial layer 611 is removed to release the second liquid storage cavity.

[0095] In this embodiment, during the removal of the first sacrificial layer 610 and the second sacrificial layer 611, the temperature is controlled at 80°C to avoid thermal stress damage to the first piezoelectric film 630 and the second piezoelectric film 631.

[0096] In this embodiment, the MEMS piezoelectric micropump has a plurality of first liquid storage cavities formed inward on the first surface 101 of the substrate 100 and a plurality of second liquid storage cavities formed inward on the second surface 102 of the substrate 100. Each first liquid storage cavity includes a first opening 200 extending from the first surface 101 into the substrate 100 and a first conical through-hole 300 located within the first opening 200. Each second liquid storage cavity includes a second opening 400 extending from the second surface 102 into the substrate 100 and a second conical through-hole 500 located within the second opening 400. Since the aperture of the first conical through-hole 300 gradually decreases from the first opening 200 into the second surface 102, for the first liquid storage cavity, the connection between the first conical through-hole 300 and the first opening 200 is an expansion-contraction tube flow channel design, thereby enabling unidirectional flow of fluid within the flow channel of the first liquid storage cavity, i.e., the fluid flows towards the small aperture of the first conical through-hole 300. Similarly, the second conical through-hole 500 connecting to the second opening 400 is also designed as an expansion-contraction tube flow channel, thereby enabling unidirectional flow of fluid within the flow channel of the second liquid storage cavity, i.e., the fluid flows towards the smaller diameter of the second conical through-hole. Furthermore, since the first and second liquid storage cavities are arranged alternately, the first conical through-hole 300 of the first liquid storage cavity is connected to the corresponding second opening 400 of the second liquid storage cavity, and the second conical through-hole 500 of the second liquid storage cavity is connected to the corresponding first opening 200 of the first liquid storage cavity. This allows adjacent first and second liquid storage cavities to be connected in series through the first conical through-hole 300 or the second conical through-hole 500. Therefore, a channel structure is formed by the alternating arrangement of several first and second liquid storage cavities. This structure itself constitutes a microchannel with unidirectional flow, completely eliminating valve fatigue problems. Simultaneously, the series connection of multiple liquid storage cavities increases the flow rate of the microchannel, further improving the stability of the MEMS piezoelectric micropump. Furthermore, by using a first piezoelectric drive unit / second piezoelectric drive unit to drive the unidirectional flow of fluid within several first liquid storage chambers / several second liquid storage chambers, the unidirectional flow rate is further increased based on the inherent unidirectional flowability of the microchannel structure. Moreover, the combined action of the second and first piezoelectric drive units significantly enhances the instantaneous velocity and average flow rate of the fluid within the microchannel. Combined with the unidirectional flow characteristics of the microchannel, high-pressure unidirectional fluid pumping is achieved under low-voltage drive. Therefore, the valveless microchannel with unidirectional flowability formed by alternating series of several first and second liquid storage chambers can significantly improve the stability of the MEMS micropump. Furthermore, the performance and fluid delivery accuracy of the MEMS micropump are further improved by combining the first and second piezoelectric drive units.

[0097] Accordingly, this invention also provides a MEMS piezoelectric micropump, which can be formed by the above method.

[0098] Please continue to refer to this. Figure 13 The MEMS piezoelectric micropump may include a substrate 100, a plurality of first liquid storage cavities, a first piezoelectric driving unit, a plurality of second liquid storage cavities, and a second piezoelectric driving unit.

[0099] Specifically, the substrate 100 may include a first surface 101 and a second surface 102 opposite to each other.

[0100] Specifically, a plurality of first liquid storage cavities are located within the substrate 100. Each first liquid storage cavity includes a first opening 200 extending from the first surface 101 into the substrate 100 and a first tapered through hole 300 located within the first opening 200. The diameter of the first tapered through hole 300 gradually decreases from the first opening 200 toward the second surface 102.

[0101] Specifically, the first piezoelectric drive unit is located on the first surface 101 and covers a plurality of first liquid storage cavities. The first piezoelectric drive unit is used to drive the fluid in the plurality of first liquid storage cavities to flow in one direction.

[0102] Specifically, a plurality of second liquid storage cavities are located within the substrate 100. Each second liquid storage cavity includes a second opening 400 extending from the second surface 102 into the substrate 100 and a second conical through-hole 500 located within the second opening 400. The diameter of the second conical through-hole 500 gradually decreases from the second opening 400 toward the first surface 101. The first liquid storage cavities and the second liquid storage cavities are arranged alternately. The first conical through-hole 300 of the first liquid storage cavity is connected to the second opening 400 of the corresponding second liquid storage cavity, and the second conical through-hole 500 of the second liquid storage cavity is connected to the first opening 200 of the corresponding first liquid storage cavity, so that adjacent first liquid storage cavities and second liquid storage cavities are connected in series through the first conical through-hole 300 or the second conical through-hole 500.

[0103] Specifically, the second piezoelectric drive unit is located on the second surface 102 and covers the second liquid storage cavity. The second piezoelectric drive unit is used to drive the fluid in the several second liquid storage cavities to flow unidirectionally. The flow direction of the fluid in the several first liquid storage cavities is the same as the flow direction of the fluid in the several second liquid storage cavities.

[0104] Specifically, the materials, formation process, working principle, specific implementation method and beneficial effects of the MEMS piezoelectric micropump in the embodiments of the present invention can be found in the preparation method of the MEMS piezoelectric micropump in the embodiments of the present invention, and will not be repeated here.

[0105] While the present invention has been disclosed above, it is not limited thereto. Any person skilled in the art can make various modifications and alterations without departing from the spirit and scope of the invention; therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A MEMS piezoelectric micropump, characterized in that, include: A substrate, the substrate comprising opposing first and second surfaces; A plurality of first liquid storage cavities are located within the substrate. Each first liquid storage cavity includes a first opening extending from the first surface into the substrate and a first tapered through hole located within the first opening. The diameter of the first tapered through hole gradually decreases from the first opening toward the second surface. A first piezoelectric drive unit is located on the first surface and covers the plurality of first liquid storage cavities. The first piezoelectric drive unit is used to drive the fluid in the plurality of first liquid storage cavities to flow in one direction. A plurality of second liquid storage cavities are located within the substrate. Each second liquid storage cavity includes a second opening extending from the second surface into the substrate and a second conical through-hole located within the second opening. The diameter of the second conical through-hole gradually decreases from the second opening towards the first surface. The first liquid storage cavities and the second liquid storage cavities are arranged alternately. The first conical through-hole of the first liquid storage cavity is connected to the second opening of the corresponding second liquid storage cavity, and the second conical through-hole of the second liquid storage cavity is connected to the first opening of the corresponding first liquid storage cavity, so that adjacent first liquid storage cavities and second liquid storage cavities are connected in series through the first conical through-hole or the second conical through-hole. The second piezoelectric drive unit is located on the second surface and covers the second liquid storage cavity. The second piezoelectric drive unit is used to drive the fluid in the plurality of second liquid storage cavities to flow unidirectionally. The flow direction of the fluid in the plurality of first liquid storage cavities is the same as the flow direction of the fluid in the plurality of second liquid storage cavities.

2. The MEMS piezoelectric micropump as described in claim 1, characterized in that, The cone angle of the first tapered through hole is 55° to 70°, and the cone angle of the second tapered through hole is 55° to 70°.

3. The MEMS piezoelectric micropump as described in claim 1, characterized in that, The first piezoelectric drive unit includes a first vibration diaphragm, a first piezoelectric film, and a first drive electrode formed sequentially from the first surface, wherein the first drive electrode corresponds to the position of the first liquid storage cavity; The second piezoelectric drive unit includes a second vibration diaphragm, a second piezoelectric film, and a second drive electrode formed sequentially from the second surface, with the second drive electrode corresponding to the position of the second liquid storage cavity.

4. The MEMS piezoelectric micropump as described in claim 3, characterized in that, Both the first driving electrode and the second driving electrode are interdigitated electrodes, and the fingers of the interdigitated electrodes are arranged along the arrangement direction of the first liquid storage cavity and the second liquid storage cavity.

5. The MEMS piezoelectric micropump as described in claim 1, characterized in that, The fluid in the first liquid storage chamber flows unidirectionally from the first opening to the first conical through hole; the fluid in the second liquid storage chamber flows unidirectionally from the second opening to the second conical through hole.

6. The MEMS piezoelectric micropump as described in claim 1, characterized in that, Also includes: The inlet is connected to the first of several alternately arranged first and second liquid storage chambers; The outlet is connected to the last of several alternating first and second liquid storage chambers.

7. A method for fabricating a MEMS piezoelectric micropump, characterized in that, include: A substrate is provided, the substrate comprising opposing first and second surfaces; A plurality of first liquid storage cavities are formed in the substrate. Each first liquid storage cavity includes a first opening extending from the first surface into the substrate and a first tapered through hole located in the first opening. The diameter of the first tapered through hole gradually decreases from the first opening toward the second surface. A first sacrificial layer is formed within the plurality of first liquid storage cavities; A first piezoelectric driving unit is formed on the surface of the first sacrificial layer, and the first piezoelectric driving unit is used to drive the fluid in the first liquid storage cavity to flow in one direction. A plurality of second liquid storage cavities are formed within the substrate. Each second liquid storage cavity includes a second opening extending from the second surface into the substrate and a second conical through-hole located within the second opening. The diameter of the second conical through-hole gradually decreases from the second opening towards the first surface. The first liquid storage cavities and the second liquid storage cavities are arranged alternately. The first conical through-hole of the first liquid storage cavity is connected to the second opening of the corresponding second liquid storage cavity, and the second conical through-hole of the second liquid storage cavity is connected to the first opening of the corresponding first liquid storage cavity, so that adjacent first liquid storage cavities and second liquid storage cavities are connected in series through the first conical through-hole or the second conical through-hole. A second sacrificial layer is formed within the plurality of second liquid storage cavities; A second piezoelectric driving unit is formed on the surface of the second sacrificial layer. The second piezoelectric driving unit is used to drive the fluid in the plurality of second liquid storage cavities to flow unidirectionally. The flow direction of the fluid in the plurality of first liquid storage cavities is the same as the flow direction of the fluid in the plurality of second liquid storage cavities. Remove the first sacrificial layer and the second sacrificial layer.

8. The preparation method according to claim 7, characterized in that, The processes for forming the first tapered via and the second tapered via both include deep reactive ion etching.

9. The preparation method according to claim 7, characterized in that, The method for forming the first piezoelectric drive unit includes: sequentially forming a first vibration diaphragm, a first piezoelectric film, and a first drive electrode material layer on the first surface and the first sacrificial layer; and performing patterning processing on the first drive electrode material layer to form a first drive electrode corresponding to the position of the first liquid storage cavity; The method for forming the second piezoelectric drive unit includes: sequentially forming a second vibration diaphragm, a second piezoelectric thin film, and a second drive electrode material layer on the second surface and the second sacrificial layer; and performing patterning processing on the second drive electrode material layer to form a second drive electrode corresponding to the position of the second liquid storage cavity.

10. The preparation method according to claim 7, characterized in that, In the process of forming a plurality of first liquid storage cavities and a plurality of second liquid storage cavities, the first opening of the first liquid storage cavity in the plurality of alternating first liquid storage cavities and second liquid storage cavities penetrates the sidewall of the substrate to form an inlet, and the second opening of the last second liquid storage cavity in the plurality of alternating first liquid storage cavities and second liquid storage cavities penetrates the sidewall of the substrate to form an outlet.

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