Piezoelectric passive flow sensor with bionic cilia sensitization structure and preparation method thereof

Abstract

The application relates to a piezoelectric passive flow sensor with a bionic cilium sensitization structure and a preparation method thereof, and relates to the field of micro-electro-mechanical system sensors. The application is aimed at solving the problems of the existing flow sensor, such as dependence on external power supply, insufficient sensitivity and high power consumption. The piezoelectric passive flow sensor with the bionic cilium sensitization structure comprises a substrate and a piezoelectric functional layer arranged on one side of the substrate, a micro flow channel is formed in the substrate, and a brush sensitization structure is arranged in the micro flow channel along the fluid flow direction. Through the mechanical action of gas flow on the brush sensitization structure, the sensing ability of the piezoelectric functional film to weak flow changes is improved. Based on the piezoelectric effect of the piezoelectric material, electric charges are generated under the action of mechanical stress, and physical quantities such as force, vibration and acceleration can be directly converted into electric signals. Finally, mechanical force is converted into electric signal output, and the effect of passive sensing is realized.

Description

Technical Field

[0001] This application belongs to the field of microelectromechanical systems (MEMS) sensor technology. Background Technology

[0002] Flow sensors are widely used in industrial automation, environmental monitoring, medical equipment, energy management, and aerospace, among other fields. Their importance lies in the real-time monitoring and control of fluid (gas or liquid) flow rates, ensuring process accuracy, equipment safety, and energy efficiency optimization. With the expansion of modern intelligent control systems, higher demands are placed on flow sensors, such as high sensitivity, miniaturization, and low power consumption. Therefore, MEMS-based miniaturized flow sensors have been widely applied in related fields.

[0003] Traditional flow sensors (such as thermal and piezoresistive sensors) suffer from drawbacks such as reliance on external power supply, insufficient sensitivity, and high power consumption. For example, thermal flow sensors detect flow by using a heating element and the heat carried away by the fluid. During operation, thermal flow sensors require continuous power to both the heating and sensing elements, and temperature drift directly affects measurement accuracy, making them unsuitable for long-term monitoring. Piezoresistive flow sensors utilize fluid impact to deform a miniature cantilever beam, detecting flow through changes in resistance. Piezoresistive flow sensors typically require variable diameter structures and bridge circuits, complicating signal processing, and their sensitivity is limited by the piezoresistive coefficient, resulting in poor response at low flow rates. Piezoelectric flow sensors usually utilize direct fluid impact on a piezoelectric thin film, but the film's high rigidity leads to insufficient sensitivity for low flow rates. Furthermore, traditional piezoelectric materials such as lead zirconate titanate (PZT) are not fully compatible with MEMS and CMOS processes. Summary of the Invention

[0004] This application aims to address the problems of existing flow sensors, such as reliance on external power supply, insufficient sensitivity, and high power consumption. It provides a piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure and its fabrication method.

[0005] The first aspect of this application provides a piezoelectric passive flow sensor with a biomimetic cilia-enhanced structure, comprising: a substrate and a piezoelectric functional layer disposed on one side of the substrate, wherein a microchannel is formed on the substrate, and a brush-enhanced structure is disposed in the microchannel along the fluid flow direction.

[0006] In one possible design, the adjacent microchannels are also provided with guide walls along the fluid flow direction.

[0007] In one possible design, the piezoelectric functional layer includes a piezoelectric layer and an upper electrode layer and a lower electrode layer disposed on both sides of the piezoelectric layer.

[0008] In one possible design, the piezoelectric layer is a piezoelectric thin film.

[0009] In one possible design, the material of the piezoelectric film includes one or more of lithium niobate, lithium tantalate, aluminum nitride, zirconium carbonate, and zinc oxide.

[0010] In one possible design, the materials of the upper and lower electrode layers include one or more of molybdenum, aluminum, copper, platinum, and gold.

[0011] In one possible design, the piezoelectric passive flow sensor with a biomimetic cilia-enhanced structure further includes a microchannel capping layer, which is fixedly connected to the other side of the substrate via a bonding layer.

[0012] In one possible design, the substrate is a silicon substrate.

[0013] The second aspect of this application provides a method for fabricating the aforementioned piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure, comprising:

[0014] A lower electrode layer, a piezoelectric layer, and an upper electrode layer are sequentially deposited on one side of the substrate.

[0015] A cilia-sensitizing structure and microchannels were photolithographically formed on the other side of the substrate.

[0016] The microchannel capping layer is bonded to the substrate using a bonding layer.

[0017] The beneficial effects of this application are:

[0018] This application leverages the mechanical action of gas flow on a brush-sensitizing structure to enhance the sensing capability of piezoelectric functional films for minute flow rate changes. Based on the piezoelectric effect of piezoelectric materials, charges are generated under mechanical stress, directly converting physical quantities such as force, vibration, and acceleration into electrical signals. The piezoelectric material is integrated with silicon-based MEMS processes via thin-film deposition, compatible with microfabrication technologies such as photolithography and etching. Simultaneously, by utilizing the piezoelectric properties of the material, mechanical force is converted into an electrical signal output, achieving passive sensing. Attached Figure Description

[0019] Figure 1 This is a cross-sectional view of the piezoelectric passive flow sensor with the biomimetic ciliary-enhanced structure described in Example 1; Figure 2 for Figure 1 AA view; Figure 3 This is a cross-sectional view of the piezoelectric passive flow sensor with the biomimetic ciliary-enhanced structure described in Example 2; Figure 4 for Figure 3 AA view; Figure 5 A flowchart illustrating the fabrication process of a piezoelectric passive flow sensor with a ciliary structure; In the figure, there are upper electrode layer 101, piezoelectric layer 102, lower electrode layer 103, silicon substrate 104, microchannel 105, microchannel capping layer 106, wafer bonding layer 107, cilia sensitizing structure 108, and flow guide wall 110. Detailed Implementation

[0025] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0026] Specific Implementation Method 1: The piezoelectric passive flow sensor with a biomimetic fibrous sensitization structure described in this embodiment includes: a substrate and a piezoelectric functional layer disposed on one side of the substrate. Microchannels are formed on the substrate, and a brush sensitization structure is disposed in the microchannels along the fluid flow direction.

[0027] In one embodiment, a guide wall is provided between the adjacent microchannels, and a guide wall along the fluid flow direction is also provided in the adjacent microchannels.

[0028] In one embodiment, the piezoelectric functional layer includes: a piezoelectric layer and an upper electrode layer and a lower electrode layer disposed on both sides of the piezoelectric layer.

[0029] In one embodiment, the piezoelectric layer is a piezoelectric thin film.

[0030] In one embodiment, the material of the piezoelectric film includes one or more of lithium niobate (LiNbO3), lithium tantalate (LiTaO3), aluminum nitride (AlN), zirconium carbonate (PZT), and zinc oxide (ZnO).

[0031] In one embodiment, the materials of the upper electrode layer and the lower electrode layer include one or more of molybdenum (Mo), aluminum (Al), copper (Cu), platinum (Pt), and gold (Au).

[0032] In one embodiment, the piezoelectric passive flow sensor with a biomimetic cilia-enhanced structure further includes a microchannel capping layer, which is fixedly connected to the other side of the substrate via a bonding layer.

[0033] This embodiment leverages the mechanical action of gas flow on the brush-sensitizing structure to enhance the sensing capability of the piezoelectric functional film to detect minute changes in flow rate. Based on the piezoelectric effect of piezoelectric materials, charges are generated under mechanical stress, directly converting physical quantities such as force, vibration, and acceleration into electrical signals. The piezoelectric material is integrated with silicon-based MEMS processes through thin-film deposition, compatible with microfabrication technologies such as photolithography and etching. Simultaneously, by utilizing the piezoelectric properties of the material, mechanical force is converted into an electrical signal output, achieving a passive sensing effect.

[0034] Example 1: To further illustrate the implementation scheme of this application, Figure 1 and Figure 2 The first piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure is provided, and is described in detail below:

[0035] like Figure 1 and Figure 2 As shown, the piezoelectric passive flow sensor with biomimetic cilia-enhanced structure described in this embodiment includes: an upper electrode layer 101, a piezoelectric layer 102, a lower electrode layer 103, a silicon substrate 104, a microchannel 105, a microchannel capping layer 106, a wafer bonding layer 107, and a cilia-enhanced structure 108.

[0036] An upper electrode layer 101, a piezoelectric layer 102, and a lower electrode layer 103 are stacked sequentially and fixed together on the upper surface of the silicon substrate 104. Microchannels 105 are formed on the silicon substrate 104, and these microchannels 105 are connected to the lower electrode layer 103. A cilia-like sensitizing structure 108 is disposed within the microchannels 105 along the fluid flow direction. The lower surface of the silicon substrate 104 is fixedly connected to the microchannel capping layer 106 via a wafer bonding layer 107.

[0037] In use, by passing the pipe containing the fluid to be measured through the microchannel capping layer 106 and connecting it to the microchannel 105, the ciliary sensitizing structure 108 is subjected to fluid impact. Under the influence of the fluid, the ciliary sensitizing structure 108 will undergo bending deformation, thereby enhancing the deformation effect of the fluid on the upper electrode layer 101, piezoelectric layer 102, and lower electrode layer 103, thus achieving the sensitization effect. Subsequently, the piezoelectric effect of the piezoelectric layer 102 generates induced charges, thereby converting the flow signal in the microchannel 105 into an electrical signal for acquisition, realizing the flow sensing effect.

[0038] Example 2: To further illustrate the implementation scheme of this application, Figure 3 and Figure 4 A second type of piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure is provided, which is described in detail below:

[0039] like Figure 3 and Figure 4As shown, the piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure described in this embodiment, compared to Embodiment 1, also has a flow guide wall 110 inside the microchannel 105. This embodiment increases the fluid velocity within the original microchannel 105 by establishing the flow guide wall 110, thereby enhancing the fluid's influence on the ciliary-enhanced structure 108 and further improving the sensor's sensitivity.

[0040] Specific Implementation Method Two: Refer to Figure 5 This embodiment specifically describes the preparation method of the piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure as described in Embodiment 1, including:

[0041] A lower electrode layer, a piezoelectric layer, and an upper electrode layer are sequentially deposited on one side of the substrate.

[0042] A cilia-sensitizing structure and microchannels were photolithographically formed on the other side of the substrate.

[0043] The microchannel capping layer is bonded to the substrate using a bonding layer.

[0044] Figure 3 In this context, 'a' indicates that the first process deposits the lower electrode layer 103 on the surface of the silicon substrate 104; Figure 3 In this context, b indicates that a piezoelectric layer 102 is deposited on the surface of silicon substrate 104 and lower electrode layer 103 based on a. Figure 3 In this context, 'c' indicates that the upper electrode layer 101 is deposited on top of 'b'. Figure 3 In the figure, d indicates that the silicon substrate 104 serves as a support substrate. Deep silicon etching is performed on the other side of the silicon substrate 104 to fabricate the cilia-sensitizing structure 108 and the microchannel 105 through silicon-based photolithography. Figure 3 The 'e' in the figure indicates that the bonding between the microchannel capping layer 106 and the silicon substrate 104 is completed through the wafer bonding layer 107.

[0045] The piezoelectric thin film is located on the upper part of the silicon substrate. It is processed by magnetron sputtering and covers the surface of the silicon substrate 104 and the cilia sensitizing structure 108 to convert mechanical deformation into electrical signals.

[0046] While specific embodiments of this application have been described herein with reference to them, it should be understood that these embodiments are merely examples of the principles and applications of this application. Therefore, it should be understood that many modifications can be made to the exemplary embodiments, and other arrangements can be designed without departing from the spirit and scope of this application as defined by the appended claims. It should be understood that different dependent claims and features described herein can be combined in ways different from those described in the original claims. It is also understood that features described in conjunction with individual embodiments can be used in other described embodiments.

Claims

1. A piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure, comprising: The substrate and the piezoelectric functional layer disposed on one side of the substrate are characterized in that the substrate has microchannels and a brush-sensitizing structure is disposed in the microchannels along the fluid flow direction.

2. A piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure, characterized in that, The adjacent microchannels are also equipped with guide walls along the fluid flow direction.

3. The piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure according to claim 1 or 2, characterized in that, The piezoelectric functional layer includes a piezoelectric layer and an upper electrode layer and a lower electrode layer disposed on both sides of the piezoelectric layer.

4. The piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure according to claim 3, characterized in that, The piezoelectric layer is a piezoelectric thin film.

5. The piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure according to claim 4, characterized in that, The materials of the piezoelectric film include one or more of lithium niobate, lithium tantalate, aluminum nitride, zirconium carbonate, and zinc oxide.

6. The piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure according to claim 5, characterized in that, The materials of the upper and lower electrode layers include one or more of molybdenum, aluminum, copper, platinum, and gold.

7. The piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure according to claim 3, characterized in that, Also includes: A microchannel capping layer is fixedly connected to the other side of the substrate via a bonding layer.

8. The piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure according to claim 3, characterized in that, The substrate is a silicon substrate.

9. A method for preparing the piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure as described in any one of claims 1 to 8, comprising: A lower electrode layer, a piezoelectric layer, and an upper electrode layer are sequentially deposited on one side of the substrate. A cilia-sensitizing structure and microchannels were photolithographically formed on the other side of the substrate.

10. The method for fabricating a piezoelectric passive flow sensor with a biomimetic ciliary-enhanced structure according to claim 9, characterized in that, Also includes: The microchannel capping layer is bonded to the substrate using a bonding layer.

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