Flexible capacitive pressure sensor based on bionic fin structure

Abstract

The invention provides a flexible capacitive pressure sensor based on a bionic fin structure. The sensor comprises an upper electrode, a lower electrode and an elastic supporting piece located between the upper electrode and the lower electrode. The elastic supporting piece comprises an upper platform, a lower platform and a plurality of bionic fin structural pieces located between the upper platform and the lower platform. The bionic fin structural member comprises an upper plane part, a lower plane part, an annular part with an opening in one side and an arc-shaped part with two arcs overlapped in a 3 shape. The upper side and the lower side, without the opening, of the annular part are connected with the upper plane part and the lower plane part correspondingly. The arc-shaped part is located in the annular part, and the two ends of the arc-shaped part are connected with the two ends of the opening of the annular part correspondingly. According to the bionic microstructure, the Young modulus of the dielectric layer is effectively reduced, the pressure response sensitivity and speed are improved, meanwhile, good structural stability and array expansibility are achieved, and the application requirement of a multi-scene intelligent interaction system is met.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible sensors, and in particular to a flexible capacitive pressure sensor based on a bionic fish fin structure. Background Art

[0002] With the rapid development of flexible electronics, flexible pressure sensors, due to their lightweight, soft, and bendable properties, have found widespread application in fields such as electronic skin, medical diagnostics, human-computer interaction, wearable devices, and robotics. Based on their operating mechanism, flexible pressure sensors can be categorized into resistive, capacitive, piezoelectric, and triboelectric types. Among them, flexible capacitive pressure sensors have attracted widespread attention due to their simple structure, low cost, and high sensitivity.

[0003] This type of sensor is typically composed of upper and lower electrodes, a dielectric layer, and an encapsulation layer. Its performance is often limited by the high Young's modulus and viscoelasticity of the dielectric material, resulting in a limited amplitude of capacitance change and a delayed response, affecting sensitivity and stability. To this end, current research focuses on two optimization aspects: first, enhancing the compressibility and responsiveness of the dielectric layer by introducing microstructures (such as biomimetic structures, pyramids, columns, cones, etc.); second, preparing a composite dielectric layer by doping it with conductive or high-dielectric-constant fillers (such as carbon nanotubes, graphene, barium titanate, titanium dioxide, etc.) to improve dielectric properties and sensing response.

[0004] Traditional microstructural fabrication methods, such as photolithography and etching, offer advantages in precision but are costly and complex. 3D printing, as an efficient and low-cost fabrication technology, enables rapid prototyping of complex structures and has become an effective alternative for microstructural design. Furthermore, doping with nano-sized high-dielectric metal fillers can enhance the dielectric properties of composite materials and improve their mechanical and dynamic stability.

[0005] Although flexible capacitive pressure sensors have made progress in sensitivity, response speed, and fabrication process, they still face problems such as narrow detection range, insufficient structural stability, and low functional integration, making it difficult to meet the actual needs of multi-scenario intelligent interactive systems. Therefore, there is an urgent need to develop a flexible capacitive pressure sensor with a reasonable structure, excellent performance, simple process, and multifunctional expansion capabilities. Summary of the Invention

[0006] Based on the technical problems existing in the background technology, the present invention proposes a flexible capacitive pressure sensor based on a bionic fish fin structure to overcome the defects of the existing technology such as high rigidity of the dielectric layer, response hysteresis and insufficient sensitivity; the sensor described in the present invention effectively reduces the Young's modulus of the dielectric layer through a bionic microstructure, improves the pressure response sensitivity and speed, and at the same time has good structural stability and array scalability, meeting the application requirements of multi-scenario intelligent interactive systems.

[0007] The present invention proposes a flexible capacitive pressure sensor based on a bionic fish fin structure, comprising an upper electrode, a lower electrode, and an elastic support member located between the upper electrode and the lower electrode;

[0008] The elastic support member includes an upper platform, a lower platform, and a plurality of bionic fish fin structures located between the upper platform and the lower platform;

[0009] The bionic fish fin structure includes an upper planar portion, a lower planar portion, an annular portion with an opening on one side, and an arc-shaped portion with two arcs overlapping to form a "3" shape; the upper and lower sides of the annular portion without an opening are respectively connected to the upper planar portion and the lower planar portion, and the arc-shaped portion is located inside the annular portion and its two ends are respectively connected to the two ends of the opening of the annular portion.

[0010] In this invention, an elastic support member comprising several bionic fish fin structures is used to stabilize and enhance the compressibility of the dielectric layer. In a bionic fish fin structure, if the arc exceeds the overlap of two arcs, the vertical height increases, resulting in a larger overall device size. Furthermore, the center of gravity of the overall structure shifts to the left, causing structural instability. Furthermore, the increased number of arcs increases resistance, making compression more difficult and reducing capacitance response.

[0011] In the present invention, copper wires are provided on both sides of the upper electrode and the lower electrode for realizing signal transmission and connection with external circuits.

[0012] Preferably, the annular openings of adjacent bionic fish fin structures (3) face in opposite directions.

[0013] Preferably, the number of the bionic fish fin structures is four;

[0014] Preferably, the spacing between adjacent bionic fish fin structures is equal and is 2-5 mm.

[0015] Preferably, the width w of the upper plane portion and the lower plane portion is 1.8 mm;

[0016] Preferably, the radius r of the annular portion is 5 mm, the thickness h is 0.5 mm, and the arc angle θ of the opening of the annular portion is 60°.

[0017] Preferably, the sensor further comprises an upper packaging layer and a lower packaging layer;

[0018] The upper packaging layer and the lower packaging layer are respectively located on a side of the upper electrode and the lower electrode away from the elastic supporting member.

[0019] Preferably, the upper packaging layer and the lower packaging layer are polyimide film layers, and the thickness is preferably 40-60 μm.

[0020] In the present invention, the polyimide film layer serves as the upper encapsulation layer and the lower encapsulation layer, and is arranged in parallel with the corresponding electrode layer, and has both insulation and flexible protection functions.

[0021] The present invention also proposes a method for preparing a flexible capacitive pressure sensor based on a bionic fish fin structure, comprising the following steps:

[0022] S1. Adding a silicone rubber / zinc oxide composite slurry into a mold having a preset bionic fish fin inner cavity shape and curing the mold, and peeling the mold to obtain a bionic fish fin structure. The bionic fish fin structure includes an upper planar portion, a lower planar portion, an annular portion with an opening on one side, and an arc-shaped portion with two arcs overlapping to form a "3" shape; the upper and lower sides of the annular portion without an opening are respectively connected to the upper planar portion and the lower planar portion; the arc-shaped portion is located inside the annular portion, and its two ends are respectively connected to the two ends of the opening of the annular portion;

[0023] S2. Connecting the upper and lower planar portions of the plurality of bionic fish fin structures to two PDMS substrates serving as an upper platform and a lower platform, respectively, to obtain an elastic support member, the elastic support member comprising an upper platform, a lower platform, and the plurality of bionic fish fin structures located between the upper and lower platforms;

[0024] S3. Laminating two conductive fabrics as upper and lower electrodes respectively onto the surfaces of two PDMS substrates as upper and lower platforms away from the bionic fish fin structure to obtain the flexible capacitive pressure sensor.

[0025] Preferably, in step S1, the main component A of the silicone rubber and the curing agent B are mixed in a mass ratio of 1:1, and then 0.5 wt% of zinc oxide nanoparticles by weight of the silicone rubber are added, and then a diluent of naphtha is added, and the mixture is stirred and mixed to obtain a silicone rubber / zinc oxide composite slurry;

[0026] Preferably, the stirring and mixing temperature is 40-50°C and the time is 1-3h;

[0027] Preferably, the curing temperature is 40-60° C. and the curing time is 4-8 hours.

[0028] In the present invention, the bionic fish fin structure is made of a composite of silicone rubber and zinc oxide nanoparticles, and will have good elasticity and dielectric response properties.

[0029] Preferably, in step S1, a resin material is 3D printed into a mold having a preset bionic fish fin inner cavity shape using 3D modeling software;

[0030] Preferably, the mold dimensional accuracy is 0.1-0.2 mm.

[0031] In this invention, the bionic fish fin structure and its corresponding mold were designed using the 3D modeling software SolidWorks 2023, ensuring that the structural dimensions and shape met the design requirements. A high-precision mold was manufactured from resin using a UnionTech Lite 600 industrial-grade 3D printer. The mold's dimensional accuracy was controlled to within 0.2 mm to ensure subsequent molding quality. A release agent was pre-sprayed on the mold surface to prevent silicone rubber from sticking and facilitate demolding.

[0032] Preferably, step S3 further comprises laminating two polyimide film layers as an upper packaging layer and a lower packaging layer respectively onto the surfaces of two conductive fabrics serving as an upper electrode and a lower electrode away from the elastic support member.

[0033] Compared with the prior art, the present invention has the following beneficial effects:

[0034] (1) The present invention is based on a bionic fish fin structure design, drawing on the streamlined shape and curved fan-shaped geometric features of the swinging fish fin to achieve a gradient distribution of stress along the radial direction during compression, effectively improving the sensor's response sensitivity to pressure and environmental adaptability. Under low-pressure conditions, the arc segments and connection parts of the structure undergo controlled micro-deformation, resulting in local compression or expansion, significantly enhancing the capacitance change and improving the sensor's sensitivity. Under high-pressure conditions, the arc segment bending and the coordinated deformation of the connection effectively alleviate excessive compression, enhance the mechanical stability and durability of the structure, and expand the sensor's detection pressure range.

[0035] (2) The present invention significantly improves the dielectric properties of the composite dielectric layer and enhances the sensor's capacitive response strength by doping the dielectric layer with high-dielectric-constant zinc oxide nanoparticles. The uniform dispersion of zinc oxide nanoparticles forms a porous microstructure, effectively reducing the viscoelasticity of the dielectric layer, reducing hysteresis, and improving response speed and signal stability. In addition, the piezoelectric effect of zinc oxide induces charge separation under pressure, synergizing with the dielectric enhancement effect to further improve the sensor's detection sensitivity and dynamic response capability to small pressure changes.

[0036] (3) The present invention achieves improved performance of flexible capacitive pressure sensors in terms of deformation response and capacitance change through the collaborative design of a bionic fish fin structure and a zinc oxide nanoparticle composite dielectric material. The curved fan-shaped structural geometry achieves effective deformation during the pressure process, significantly shortening the distance between the upper and lower electrodes and increasing the amplitude of capacitance change; at the same time, the composite dielectric layer reinforced with zinc oxide filler has excellent dielectric properties and compressibility, helping the structure achieve efficient energy conversion and signal output. This structure-material collaborative optimization design not only improves sensitivity and response speed, but also reduces local stress concentration, improves the mechanical stability and fatigue life of the device, and significantly broadens the pressure detection range and dynamic response capability of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 1 is a schematic diagram of the overall structure of the flexible capacitive pressure sensor according to an embodiment of the present invention;

[0038] Figure 2 The specific parameter design of the bionic fish fin structure in the sensor according to the embodiment of the present invention;

[0039] Figure 3 1 is a schematic diagram of the preparation process of the flexible capacitive pressure sensor according to an embodiment of the present invention;

[0040] Figure 4 1 is a diagram showing the finite element simulation results of the bionic fish fin structure according to an embodiment of the present invention, the traditional C-shaped structure, and the double-arc structure under the same displacement;

[0041] Figure 5 2. This is a diagram showing the electrostatic field simulation results of the bionic fish fin structure according to an embodiment of the present invention;

[0042] Figure 6 1 is a comparison diagram of the relationship between the capacitance signal output and the loading pressure of the sensors corresponding to the bionic fish fin structure according to the embodiment of the present invention, the traditional C-shaped structure, and the double-arc structure;

[0043] Figure 7 Schematic diagram of the effects of different parameter designs of the bionic fish fin structure and different zinc oxide contents on the pressure response performance of the sensor according to an embodiment of the present invention;

[0044] Figure 8 Schematic diagram of the relationship between pressure and capacitance response of the flexible capacitive pressure sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0045] Hereinafter, the technical solutions of the present invention will be described in detail through specific embodiments. However, it should be clearly stated that these embodiments are provided for illustration only and are not to be construed as limiting the scope of the present invention.

[0046] Example

[0047] Figure 1 is a schematic diagram of the overall structure of the flexible capacitive pressure sensor according to an embodiment of the present invention; Figure 1 This embodiment provides a flexible capacitive pressure sensor based on a bionic fish fin structure, comprising an upper electrode 1, a lower electrode 2, and an elastic support member 3 located between the upper electrode 1 and the lower electrode 2. In this embodiment, the upper electrode 1 and the lower electrode 2 are both conductive fabric electrodes.

[0048] The elastic structure 3 includes an upper platform 31, a lower platform 32, and four bionic fish fin structures 30 located between the upper platform 31 and the lower platform 32. In this embodiment, the upper platform 31 and the lower platform 32 are PDMS substrates and are arranged in parallel.

[0049] The bionic fish fin structure 30 includes an upper planar portion, a lower planar portion, an annular portion with an opening on one side, and an arc-shaped portion with two arcs overlapping to form a "3" shape; the upper and lower sides of the annular portion without an opening are respectively connected to the upper planar portion and the lower planar portion, and the arc-shaped portion is located inside the annular portion and its two ends are respectively connected to the two ends of the opening of the annular portion; in this embodiment, four bionic fish fin structures 30 are arranged in parallel and equidistantly between the upper platform 31 and the lower platform 32, and the upper planar portion and the lower planar portion of each bionic fish fin structure 30 are tightly bonded to the upper platform 31 and the lower platform 32 by a silicone rubber adhesive; the openings of the annular portions of adjacent bionic fish fin structures 30 face opposite directions; Figure 2 For the specific parameter design of the bionic fish fin structure in the sensor according to the embodiment of the present invention, refer to Figure 2 In this embodiment, in each bionic fish fin structure 30, the annular portion is distributed in a fan shape, with a radius r of 5 mm, an opening arc θ of 60°, a length l of the upper plane portion and the lower plane portion of 13.72 mm, a width w of 1.8 mm, a thickness h of 0.5 mm, and a spacing between adjacent bionic fish fin structures 30 of 3 mm;

[0050] In this embodiment, an upper packaging layer 4 and a lower packaging layer 5 are also included. The upper packaging layer 4 and the lower packaging layer 5 are respectively located on the side surface of the upper electrode 1 and the lower electrode 2 away from the elastic support member 3, and encapsulate the upper electrode 1 and the lower electrode 2; in this embodiment, the upper packaging layer 4 and the lower packaging layer 5 are polyimide (PI) film layers with a thickness of 50 μm.

[0051] Figure 3 This is a schematic diagram of the preparation process of the flexible capacitive pressure sensor according to an embodiment of the present invention, referring to Figure 3 This embodiment also proposes a method for preparing a flexible capacitive pressure sensor based on a bionic fish fin structure, which specifically includes:

[0052] (1) Use 3D modeling software (SolidWorks 2023) to design the mold corresponding to the bionic fin structure to ensure that the microstructure size and geometric shape meet the design requirements. Then use the Liantai Technology Lite600 industrial-grade 3D printer to select resin materials for high-precision printing of the preset mold. The mold size accuracy is controlled within the range of ±0.2mm to ensure the accuracy and consistency of the structural molding. After the mold is printed, the release agent is evenly sprayed on its surface to prevent the silicone rubber from adhering to the mold during the subsequent molding process, which facilitates smooth demolding.

[0053] (2) After the main component A and curing agent B of Yipin PS6600 silicone rubber are fully mixed in a mass ratio of 1:1, 0.5% of the mass of the silicone rubber is added with zinc oxide nanoparticles, and then naphtha is added as a diluent. After magnetic stirring and mixing at 45°C for 1 hour, it is ensured that the zinc oxide nanoparticles are evenly dispersed in the silicone rubber; the obtained silicone rubber / zinc oxide composite slurry is slowly poured into the mold with the preset bionic fish fin structure shape printed by the 3D printer, and is placed in a vacuum chamber to maintain a vacuum state for 30 minutes to effectively remove the gas inside the material. The mold is then transferred to a drying oven and cured at 50°C for 6 hours to fully cross-link the material and finalize the structure. After the curing is completed, the mold is naturally cooled to room temperature and demolded to obtain a bionic fish fin structure. The bionic fish fin structure includes an upper plane portion, a lower plane portion, and an annular portion with an opening on one side located between the upper plane portion and the lower plane portion, and an arc-shaped portion with two arcs overlapping in a "3" shape; the upper and lower sides of the annular portion without an opening are respectively connected to the upper plane portion and the lower plane portion, and the arc-shaped portion is located inside the annular portion and its two ends are respectively connected to the two ends of the opening of the annular portion;

[0054] (3) Arranging four bionic fish fin structures in parallel and equidistantly, with the openings of the annular portions of adjacent bionic fish fin structures facing opposite directions, and using Yipin PS6600 silicone rubber adhesive to connect the upper and lower planar portions of the four bionic fish fin structures to the two PDMS substrates serving as the upper and lower platforms, respectively, to obtain an elastic support member;

[0055] (3) Laminating two conductive fabrics as the upper electrode and the lower electrode onto the surface of the two PDMS substrates as the upper platform and the lower platform away from the bionic fish fin structure, and inserting copper wires between the upper electrode, the lower electrode and the PDMS substrate to realize the extraction of external capacitance signals;

[0056] (4) The two polyimide film layers serving as the upper packaging layer and the lower packaging layer are laminated onto the surfaces of the two conductive fabrics serving as the upper electrode and the lower electrode, respectively, away from the elastic support member. The two conductive fabrics are then placed in a constant temperature vacuum drying oven and further dried at 50°C for 3 hours to remove residual solvent and moisture and ensure stable sensor performance, thereby obtaining the flexible capacitive pressure sensor.

[0057] Figure 4 This is a finite element simulation result diagram of the bionic fish fin structure, the traditional C-shaped structure and the double-arc structure under the same displacement. Figure 4 It can be seen that the bionic fish fin structure can concentrate stress in the arc area under small displacement, achieve greater deformation, and improve pressure response sensitivity; under large displacement, the stress distribution is more uniform, effectively alleviating local stress concentration, and improving structural stability and compressive resistance; therefore, compared with traditional structures, this bionic design has both high sensitivity and a wide detection range.

[0058] Figure 5 This is a diagram of the electrostatic field simulation results of the bionic fish fin structure described in an embodiment of the present invention, including the electric field strength and potential distribution. The simulation is based on the electrostatic module of COMSOL Multiphysics 6.2, setting a 5V voltage difference between the upper and lower electrodes to analyze the electric field behavior of the bionic fish fin structure. Figure 5 It can be seen that the electric field is significantly enhanced in the electrode contact area and the center of the bionic fish fin structure, and the electric potential forms a clear gradient distribution between the upper and lower electrodes, reflecting good electric field concentration ability; in addition, the uniform electric field distribution helps to suppress parasitic effects and noise interference, improve the stability and repeatability of signal output, and provide theoretical support for the high sensitivity and reliability of flexible sensors.

[0059] Figure 6 : is a comparison diagram of the relationship between the capacitance signal output and the loading pressure of the corresponding sensors of the bionic fish fin structure according to the embodiment of the present invention, the traditional C-shaped structure, and the double-arc structure. Figure 6 The actual comparison of the capacitance changes of the bionic fish fin structure, traditional C-shaped structure and double arc structure under different pressures is made. Figure 6 It can be seen that under the same loading conditions, the bionic fish fin structure exhibits a greater capacitance change, higher sensitivity, and a wider response range. This is mainly due to its unique fan-shaped curved surface design, which can achieve more significant structural compression and electrode spacing changes during force application. In contrast, the C-type and double-arc structures have limited deformation, resulting in weaker capacitance response and a relatively narrow response range. This result further verifies the effectiveness of bionic fish fin structure design in improving the performance of flexible capacitive sensors.

[0060] Figure 7 This is a schematic diagram of the effects of different parameter designs of the bionic fish fin structure and different zinc oxide contents on the pressure response performance of the sensor according to the embodiment of the present invention. It actually shows the systematic optimization process of the key geometric parameters and filler ratio in the bionic fish fin structure on the performance of the sensor. In order to improve the sensitivity and structural stability of the sensor, this embodiment respectively examines the effects of the annular arc radius (r), thickness (h), annular opening radian (θ) and zinc oxide doping ratio on the capacitance response. Figure 7It can be seen that when r = 5mm, h = 0.5mm, θ = 60°, and the zinc oxide doping mass fraction is 0.5%, the sensor exhibits optimal sensitivity and response performance in the pressure range of 0-400kPa; a smaller r value limits the compression deformation, while a larger r value causes lateral displacement, both of which are not conducive to sensitivity improvement; if h is too small, the structure will be fragile, and if it is too large, it will inhibit compression, and the optimal value is 0.5mm; when the θ angle is 60°, it provides the most suitable deformation path and increases the capacitance change amplitude; an appropriate amount of zinc oxide filler enhances the dielectric constant and maintains flexibility, and the optimal performance is achieved at 0.5% doping; the optimization results provide a theoretical basis and experimental support for the structural parameter design of flexible pressure sensors.

[0061] Figure 8 This is a schematic diagram of the relationship between pressure and capacitance response of the flexible capacitive pressure sensor according to an embodiment of the present invention. It essentially shows the capacitance response curve of the flexible sensor of this embodiment under different applied pressures, showing a typical three-stage response characteristic. Figure 8 It can be seen that the sensor shows 5.096kPa in the three stages of low pressure (0-1kPa), medium pressure (1-10kPa) and high pressure (10-400kPa) respectively. -1 , 1.081kPa -1 and 0.053kPa -1 The sensitivity of the bionic arc structure is excellent, indicating its good segmented response capability. In the low-pressure range, the external force acts primarily on the curved region of the bionic arc structure, causing the gap between the arcs to compress rapidly, thereby inducing a significant change in relative capacitance and achieving a highly sensitive response. As the pressure increases to the medium-pressure region, the structural deformation area expands to the curved and connecting segments, the amplitude of the capacitance change per unit pressure slows, and the sensitivity reaches an intermediate level. In the high-pressure region, the structure approaches the compression limit, deformation is limited, the capacitance response tends to saturate, and the sensitivity drops to the minimum. This piecewise linear characteristic not only reflects the sensor's good wide-range adaptability, but also embodies the electromechanical synergistic response mechanism of the bionic structure under different stress regions, providing a theoretical basis for multi-level pressure sensing in practical applications.

[0062] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A flexible capacitive pressure sensor based on a bionic fish fin structure, characterized in that: It comprises an upper electrode (1), a lower electrode (2), and an elastic support member (3) located between the upper electrode (1) and the lower electrode (2); The elastic support member (3) comprises an upper platform (31), a lower platform (32), and a plurality of bionic fish fin structures (30) located between the upper platform (31) and the lower platform (32); The bionic fish fin structure (30) comprises an upper plane portion, a lower plane portion, an annular portion with an opening on one side, and an arc-shaped portion with two arcs overlapping to form a "3" shape; the upper and lower sides of the annular portion without an opening are respectively connected to the upper plane portion and the lower plane portion; the arc-shaped portion is located inside the annular portion and its two ends are respectively connected to the two ends of the opening of the annular portion.

2. The flexible capacitive pressure sensor based on the bionic fish fin structure according to claim 1, characterized in that: The annular openings of adjacent bionic fish fin structural members (3) face in opposite directions.

3. The flexible capacitive pressure sensor based on the bionic fish fin structure according to claim 1 or 2, characterized in that: The number of the bionic fish fin structural members (3) is four; Preferably, the spacing between adjacent bionic fish fin structures (3) is equal and is 2-5 mm.

4. The flexible capacitive pressure sensor based on a bionic fish fin structure according to any one of claims 1 to 3, characterized in that: The width w of the upper plane portion and the lower plane portion is 1.8 mm; Preferably, the radius r of the annular portion is 5 mm, the thickness h is 0.5 mm, and the arc angle θ of the opening of the annular portion is 60°.

5. The flexible capacitive pressure sensor based on a bionic fish fin structure according to any one of claims 1 to 4, characterized in that: The sensor further comprises an upper packaging layer (4) and a lower packaging layer (5); The upper packaging layer (4) and the lower packaging layer (5) are respectively located on a side of the upper electrode (1) and the lower electrode (2) away from the elastic support member (3).

6. The flexible capacitive pressure sensor based on the bionic fish fin structure according to claim 5, characterized in that: The upper packaging layer (4) and the lower packaging layer (5) are polyimide film layers, and the thickness is preferably 40-60 μm.

7. A method for preparing a flexible capacitive pressure sensor based on a bionic fish fin structure, characterized in that: The steps include: S1. Adding a silicone rubber / zinc oxide composite slurry into a mold having a preset bionic fish fin inner cavity shape and curing the mold, and peeling the mold to obtain a bionic fish fin structure. The bionic fish fin structure includes an upper planar portion, a lower planar portion, an annular portion with an opening on one side, and an arc-shaped portion with two overlapping arcs forming a "3" shape; the upper and lower sides of the annular portion without an opening are respectively connected to the upper planar portion and the lower planar portion; the arc-shaped portion is located inside the annular portion and its two ends are respectively connected to the two ends of the opening of the annular portion; S2. Connecting the upper and lower planar portions of the plurality of bionic fish fin structures to two PDMS substrates serving as an upper platform and a lower platform, respectively, to obtain an elastic support member, the elastic support member comprising an upper platform, a lower platform, and the plurality of bionic fish fin structures located between the upper and lower platforms; S3. Laminating two conductive fabrics as upper and lower electrodes respectively onto the surfaces of two PDMS substrates as upper and lower platforms away from the bionic fish fin structure to obtain the flexible capacitive pressure sensor.

8. The method for preparing a flexible capacitive pressure sensor based on a bionic fish fin structure according to claim 7, characterized in that: In step S1, the main component A of silicone rubber and the curing agent B are mixed at a mass ratio of 1:1, and then 0.5 wt% of zinc oxide nanoparticles by weight of the silicone rubber are added, and then naphtha diluent is added, and the mixture is stirred and mixed to obtain a silicone rubber / zinc oxide composite slurry; Preferably, the stirring and mixing temperature is 40-50°C and the time is 1-3h; Preferably, the curing temperature is 40-60° C. and the curing time is 4-8 hours.

9. The method for preparing a flexible capacitive pressure sensor based on a bionic fish fin structure according to claim 7 or 8, characterized in that: In step S1, a resin material is 3D printed into a mold having a preset bionic fish fin inner cavity shape using 3D modeling software; Preferably, the mold dimensional accuracy is 0.1-0.2 mm.

10. The method for preparing a flexible capacitive pressure sensor based on a bionic fish fin structure according to any one of claims 7 to 9, characterized in that: Step S3 further includes laminating two polyimide film layers as an upper packaging layer and a lower packaging layer respectively onto the surfaces of two conductive fabrics serving as an upper electrode and a lower electrode away from the elastic support member.

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