Capacitive proximity-pressure dual-function flexible sensor based on bionic snail

Abstract

The invention provides a capacitive proximity-pressure dual-function flexible sensor based on a bionic snail. The sensor comprises an upper flexible electrode, a lower flexible electrode and an elastic structural member, the elastic structural part comprises an upper platform, a lower platform and a plurality of bionic snail parts located between the upper platform and the lower platform. The bionic snail piece comprises an upper plane part, a lower plane part, an annular part and a V-shaped part, wherein the annular part and the V-shaped part are located between the upper plane part and the lower plane part. The upper plane part is connected with the upper platform, and the lower plane part is connected with the lower platform; the bottom of the annular part is connected with the lower plane part, and the top of the annular part is provided with an opening; two branches of the V-shaped part are connected with two ends of the opening of the annular part and extend upwards to be connected with the upper plane part; the upper flexible electrode and the lower flexible electrode are located on the surfaces of the sides, away from the bionic snail piece, of the upper platform and the lower platform correspondingly. The pressure sensor is novel in structure, can be expanded into arrays with different sizes, has higher pressure detection sensitivity and wider detection range, and also has wide-range proximity response.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible sensors, and particularly to a capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail. Background Art

[0002] Breakthroughs in robotics and large language models, such as the DeepSeek-R1 inference model, have propelled embodied intelligent robots from traditional information interaction to a higher level of environmental perception and autonomous decision-making. Against this backdrop, flexible electronic devices, with their outstanding adaptability, mechanical compliance, and environmental interaction capabilities, have become a crucial bridge between the physical world and intelligent systems. These devices have extensive application scenarios in virtual reality, augmented reality, and human-machine interfaces. However, with the complexity and diversification of application scenarios, the demand for sensing technology has been increasing, especially in multi-modal perception and multi-functional integration. Traditional single-functional flexible sensors have difficulty meeting the response requirements for various external stimuli in complex environments.

[0003] Currently, research on capacitive pressure sensors at home and abroad mainly focuses on single-mode detection capabilities and lacks in-depth exploration of multi-modal responses. Such single-functional sensors often show limitations in complex environments and cannot simultaneously handle the combined effects of various external stimuli such as pressure, temperature, and humidity. Therefore, developing flexible sensors with multi-functional integration capabilities has become an important research direction. To address this limitation, researchers have integrated proximity sensing functions into capacitive pressure sensors, enabling them to not only detect pressure changes but also sense the presence, position, or movement of target objects within a certain range. For example, Wang et al. constructed a flexible iontronic dual-responsive artificial skin that is sensitive to the pressure exerted by external objects and their proximity and can extract information on the target material categories encoded in proximal inputs (A dual-responsive artificial skin for tactile and touchless interfaces, Small, 2023).

[0004] Currently, domestic and foreign sensors mainly have two deficiencies: First, high-sensitivity sensors are often accompanied by complex and costly manufacturing processes, making it difficult to achieve large-scale popularization and application; Second, it is difficult for flexible pressure sensors to have both high sensitivity and a wide detection range. Therefore, through reasonable design of the sensor structure, alleviating the impact of sensitivity caused by the limitation of the sensor's own compression modulus has become a feasible strategy to improve the sensitivity of capacitive tactile sensors. Exploring flexible sensors with multiple functions to achieve multi-modal perception to improve the accuracy of information perception has become a hot research field. Summary of the Invention

[0005] Based on the technical problems existing in the background art, the present invention proposes a capacitive proximity-pressure dual-functional sensor based on a bionic snail, which has a novel structure, can be expanded into different-sized arrays, has higher pressure detection sensitivity, a wider detection range, and also has a wide-range proximity response.

[0006] A capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail proposed by the present invention includes an upper flexible electrode, a lower flexible electrode, and an elastic structural member;

[0007] The elastic structural member includes an upper platform, a lower platform, and a plurality of bionic snail members located between the upper platform and the lower platform;

[0008] The bionic snail member includes an upper planar portion, a lower planar portion, and an annular portion and a V-shaped portion located between the upper planar portion and the lower planar portion; the upper planar portion is connected to the upper platform, and the lower planar portion is connected to the lower platform; the bottom of the annular portion is connected to the lower planar portion and the top of the annular portion has an opening, and the two branches of the V-shaped portion are connected to both ends of the opening of the annular portion and the two branches extend upward and are connected to the upper planar portion;

[0009] The upper flexible electrode and the lower flexible electrode are respectively located on one side surface of the upper platform and the lower platform away from the bionic snail member.

[0010] Preferably, the upper flexible electrode and / or the lower flexible electrode has a through hole in the middle;

[0011] Preferably, the upper flexible electrode and / or the lower flexible electrode is a square annular electrode with a square through hole in the middle, and the ratio of the outer side length a to the inner side length b of the square annular electrode is 4:3.

[0012] In the present invention, using a square annular electrode for the upper flexible electrode and / or the lower flexible electrode can improve the proximity response of the sensor; when the sensor receives a proximity signal, the annular electrodes of the upper flexible electrode and / or the lower flexible electrode are non-uniform electrodes, and the electric field intensity in the edge region will be stronger than that in the central region, causing the intensification of the electric field in these edge regions and realizing the wide-range proximity response of the sensor.

[0013] In the actual use of the present invention, one copper wire is led out from both the upper flexible electrode and the lower flexible electrode.

[0014] Preferably, the upper flexible electrode and the lower flexible electrode are conductive fabrics.

[0015] Preferably, the included angle θ between the two branches of the V-shaped portion is 25°, and the ratio of the radius r of the annular portion to the distance h from the top of the annular portion to the upper planar portion is 3:2.

[0016] Preferably, it further includes an upper encapsulation layer and a lower encapsulation layer;

[0017] The upper encapsulation layer and the lower encapsulation layer are respectively located on one side surface of the upper flexible electrode and the lower flexible electrode away from the elastic structural member, and encapsulate the upper flexible electrode and the lower flexible electrode;

[0018] Preferably, the sizes of the upper encapsulation layer and the lower encapsulation layer are respectively the same as those of the upper flexible electrode and the lower flexible electrode.

[0019] Preferably, the upper encapsulation layer and the lower encapsulation layer are polyimide (PI) film layers.

[0020] Preferably, the number of the biomimetic snail parts (30) is four.

[0021] In the present invention, the elastic structural member includes four biomimetic snail parts arranged in parallel.

[0022] The present invention also provides a preparation method of a biomimetic snail capacitive proximity-pressure dual-functional flexible sensor, including the following steps:

[0023] S1. Add a PDMS solution into a mold with a preset inner cavity shape and cure it. After peeling, a biomimetic snail part is obtained. The biomimetic snail part includes an upper flat part, a lower flat part, an annular part and a V-shaped part located between the upper flat part and the lower flat part. The bottom of the annular part is connected to the lower flat part and the top of the annular part has an opening. Two branches of the V-shaped part are connected to both ends of the opening of the annular part and the two branches extend upward to be connected to the upper flat part;

[0024] S2. Connect the upper flat parts and the lower flat parts of several biomimetic snail parts to two PDMS film layers serving as the upper platform and the lower platform respectively, and an elastic structural member is obtained. The elastic structural member includes an upper platform, a lower platform and several biomimetic snail parts located between the upper platform and the lower platform;

[0025] S3. Laminate two conductive fabrics as the upper flexible electrode and the lower flexible electrode respectively to one side surface of the two PDMS film layers serving as the upper platform and the lower platform away from the biomimetic snail parts, and thus the capacitive proximity-pressure dual-functional sensor is obtained.

[0026] In the present invention, the 3D printing process is adopted. The mold with a preset inner cavity shape is essentially a mold with a BSA (Biomimetic Snail Antenna) structure, which is designed by using SolidWorks 2023 3D modeling software and exported as an STL file; then the model is sliced in Bambu Studio, and a smaller layer height and a higher filling density are selected to improve the mold accuracy; subsequently, a TopTree P1S high-precision 3D printer is used to manufacture the mold to ensure accurate structure replication.

[0027] Preferably, in step S1, the main component A of PDMS and the curing agent B are mixed at a mass ratio of 10:1 as the PDMS solution;

[0028] Preferably, the curing temperature is 40-60°C and the time is 4-8h.

[0029] Preferably, in step S2, a blade die is used to cut the conductive fabric serving as the upper flexible electrode and / or the lower flexible electrode under the action of a die cutter to form a square annular electrode, and a square through-hole is provided in the center of the square annular electrode.

[0030] Preferably, in step S3, two polyimide film layers are further laminated to the surfaces of the two conductive fabrics serving as the upper flexible electrode and the lower flexible electrode away from the elastic structural member as the upper encapsulation layer and the lower encapsulation layer respectively.

[0031] In the present invention, four elastic structural members with a BSA structure are evenly positioned between two PDMS film layers and bonded using a silicone rubber adhesive to enhance stability; thereafter, the conductive fabric is precisely cut into a square annular electrode, and then the square annular electrode is laminated onto the PDMS film layer, and a copper wire is inserted between the square annular electrode and the PDMS film layer to collect electrical signals; the precisely cut PI film is also laminated onto the annular electrode to improve the encapsulation integrity and electrical insulation, and at the same time optimize the edge electric field effect to maintain excellent proximity sensing performance.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) In the present invention, a unique elastic structural member with a bionic snail antenna structure is introduced in the middle of the capacitive flexible sensor, and the electrodes are prepared using a commercial conductive fabric; this dielectric layer design is beneficial for staged compression behavior, causing capacitance changes under the applied pressure, thereby significantly enhancing the overall performance of the sensor.

[0034] (2) The flexible sensor of the present invention adopts a bionic snail antenna structure. Compared with the traditional sensor structure, under the same force conditions, the bionic snail antenna structure has characteristics such as good stability, high sensitivity, and good repeatability.

[0035] (3) The present invention introduces an annular electrode above the capacitive flexible sensor, and uses the edge field enhancement effect to improve the proximity response ability of the sensor, significantly broadening the proximity response range of the sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 is a schematic diagram of the overall structure of the sensor according to an embodiment of the present invention;

[0037] Figure 2 is a schematic diagram of the preparation process of the sensor according to an embodiment of the present invention;

[0038] Figure 3It is the specific parameter design of the bionic snail component in the sensor described in the embodiment of the present invention;

[0039] Figure 4 It is a schematic diagram showing the influence of different parameter designs of the bionic snail component in the sensor described in the embodiment of the present invention on the relationship between the sensor signal output and the applied force;

[0040] Figure 5 It is a comparison diagram of the bionic snail antenna structure and other related simulation structures in the sensor described in the embodiment of the present invention: (a) is a circular structure; (b) is a V-bridge structure; (c) is a bottleneck structure; (d) is a bionic snail antenna structure;

[0041] Figure 6 It is a schematic diagram showing the relationship between the pressure and the capacitance response of the sensor described in the embodiment of the present invention;

[0042] Figure 7 It is a simulation schematic diagram showing the influence of the electrode design in the sensor described in the embodiment of the present invention on the proximity electric field: (a) is a common square electrode; (b) is a square ring electrode; (c) is a ring electrode under the approach of a conductor;

[0043] Figure 8 It is a schematic diagram showing the influence of the ratio of the inner and outer side lengths of the square ring electrode in the sensor described in the embodiment of the present invention on the proximity response. Detailed implementation manners

[0044] Next, 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 for illustrative purposes only and are not construed as limiting the scope of the present invention.

[0045] Embodiment

[0046] Referring to Figure 1 , this embodiment proposes a capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail, including an upper flexible electrode 1, a lower flexible electrode 2, and an elastic structure member 3;

[0047] The elastic structure member 3 includes an upper platform 31, a lower platform 32, and four bionic snail members 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 square PDMS film layers, and the two are arranged in parallel;

[0048] The bionic snail part 30 includes an upper flat part, a lower flat part, an annular part and a V-shaped part located between the upper flat part and the lower flat part; the upper flat part is connected to the upper platform 31, and the lower flat part is connected to the lower platform 32; the bottom of the annular part is connected to the lower flat part and the top of the annular part has an opening, and the two branches of the V-shaped part are connected to both ends of the opening of the annular part and the two branches extend upward and are connected to the upper flat part; in this embodiment, the bionic snail part 30 is formed by molding a PDMS solution through a mold with a preset inner cavity shape printed by a 3D printer; in this embodiment, four bionic snail parts 30 are arranged in parallel and at equal distances, and each bionic snail part 30 is tightly bonded to the upper platform 31 and the lower platform 32 through the upper flat part and the lower flat part by a silicone rubber adhesive;

[0049] The upper flexible electrode and the lower flexible electrode are respectively located on one side surface of the upper platform and the lower platform away from the bionic snail part; in this embodiment, the upper flexible electrode and the lower flexible electrode are conductive fabrics, which are directly located on one side surface of the upper platform or the lower platform away from the bionic snail part; in this embodiment, the upper flexible electrode is a square annular electrode with a square through hole in the middle, and the ratio of the outer side length a to the inner side length b of the square annular electrode is 4:3, and the lower flexible electrode is a square electrode with the same size as the upper flexible electrode, and the two are arranged in parallel; in actual use, both the upper flexible electrode and the lower flexible electrode are led out by a copper wire;

[0050] In this embodiment, an upper encapsulation layer 4 and a lower encapsulation layer 5 are also respectively included. The upper encapsulation layer 4 and the lower encapsulation layer 5 are respectively located on one side surface of the upper flexible electrode 1 and the lower flexible electrode 2 away from the elastic structure part 3, and encapsulate the upper flexible electrode 1 and the lower flexible electrode 2; in a preferred embodiment, the upper encapsulation layer and the lower encapsulation layer are shielding protection layers of the sensor, and they can be PI film layers.

[0051] Referring to Figure 2 , this embodiment also proposes a preparation method of a capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail, which specifically includes:

[0052] (1) Mix the main component A of PDMS and the curing agent B (Dow Corning DC184) in a mass ratio of 10:1 as the PDMS solution, add it to a mold with a preset inner cavity shape, first place it in a vacuum chamber for 45 minutes to eliminate the bubbles generated during the mixing process, and then transfer the mold to a drying oven and cure it at 50°C for 6 hours. After peeling, a bionic snail part is obtained. The bionic snail part includes an upper flat part, a lower flat part, an annular part and a V-shaped part located between the upper flat part and the lower flat part. The bottom of the annular part is connected to the lower flat part and the top of the annular part has an opening. The two branches of the V-shaped part are connected to both ends of the opening of the annular part and the two branches extend upward and are connected to the upper flat part;

[0053] (2) The upper and lower planar parts of the four bionic snail parts are respectively connected to two PDMS film layers serving as the upper platform and the lower platform by using a silicone rubber binder (purchased from Zhonghao Chenguang Research Institute of Chemical Industry Co., Ltd.). The four bionic snail parts are arranged parallel and equidistantly between the two PDMS film layers serving as the upper platform and the lower platform, obtaining an elastic structural part;

[0054] (3) Two conductive fabrics serving as the upper flexible electrode and the lower flexible electrode are cut by using a customized blade die under the action of a die-cutting machine. The upper flexible electrode is a square annular electrode with a square through-hole in the middle. The ratio of the outer side length a to the inner side length b of the square annular electrode is 4:3. The lower flexible electrode is a square electrode with the same size as the upper flexible electrode. They are respectively laminated to the surfaces of the two PDMS film layers serving as the upper platform and the lower platform away from the bionic snail parts. Copper wires are inserted between the annular electrode and the PDMS film layer to collect electrical signals;

[0055] (4) Two polyimide film layers serving as the upper encapsulation layer and the lower encapsulation layer are cut by using a customized blade die under the action of a die-cutting machine. The two cut polyimide film layers are respectively laminated to the surfaces of the two conductive fabrics serving as the upper flexible electrode and the lower flexible electrode away from the elastic structural part, thus obtaining the capacitive proximity-pressure dual-functional sensor.

[0056] Figure 3 is the specific parameter design of the bionic snail part in the sensor described in the embodiment of the present invention. From Figure 3 it can be seen that the upper and lower planar parts of each bionic snail part are cuboids with a length, width and height (w) of 12.4×1.8×0.5 mm. The distance from the top of the annular part to the upper planar part is h = 3.34 mm. The radius of the annular part is r = 5 mm, and the ratio of r to h is 3:2. The included angle θ between the two branches of the V-shaped part is 25°.

[0057] Figure 4 is a schematic diagram showing the influence of different parameter designs of the bionic snail part in the sensor described in the embodiment of the present invention on the relationship between the sensor signal output and the applied force. From Figure 4 it can be seen that by designing and optimizing different angles, heights, radii and widths, the most ideal sensor microstructure parameters can be obtained and the sensitivity of the sensor can be improved.

[0058] Figure 5 is a comparison diagram of the bionic snail antenna structure and other related simulation structures in the sensor described in the embodiment of the present invention. In essence, it is a finite element simulation result diagram based on COMSOL. From Figure 5It can be seen that the stress in the circular and V-shaped bridge structures is mainly located at the top and bottom of the arc, effectively resisting external forces but showing minimal structural deformation. In contrast, the bottleneck and bionic snail structures show greater stress distribution in the middle and along the arc edge, indicating that the bio-inspired design enhances the compressive deformation of the dielectric layer, thus causing a more significant change in the electrode spacing and increasing the capacitance output under the same pressure conditions. In addition, at large displacements, the arc portions of the circular and V-bridge structures extend beyond the substrate boundary, resulting in potential non-linear capacitance changes. It can be seen that choosing the bionic snail antenna structure is beneficial for obtaining the best capacitance response.

[0059] Figure 6 It is a schematic diagram showing the relationship between the sensor pressure and the capacitance response in the embodiment of the present invention. As Figure 6 can be seen, the sensor in the embodiment of the present invention has both wide-range pressure detection ability and high sensitivity.

[0060] Figure 7 It is a schematic diagram of the simulation of the influence of the electrode design on the proximity electric field in the sensor of the embodiment of the present invention. Figure 7 It shows the electric field distributions of a common square electrode and a square ring electrode. It can be seen that the design of the ring electrode effectively enhances the edge field effect, which helps to improve the proximity response of the sensor.

[0061] Figure 8 It is a schematic diagram showing the influence of the ratio of the outer and inner side lengths of the square ring electrode on the proximity response in the sensor of the embodiment of the present invention. As Figure 8 can be seen, when the ratio of the outer side length a to the inner side length b of the square ring electrode is 4:3, that is, when the outer and inner side lengths are 9.3 mm and 12.4 mm respectively, it has a wide range of proximity responses.

[0062] As described above, the above are only the preferred specific embodiments of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art within the technical scope disclosed by the present invention, according to the technical solution of the present invention and its inventive concept, makes equivalent substitutions or changes, and all should be covered within the protection scope of the present invention.

Claims

1. A capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail, characterized in that, It includes an upper flexible electrode (1), a lower flexible electrode (2) and an elastic structural member (3); The elastic structural member (3) includes an upper platform (31), a lower platform (32) and a number of bionic snail members (30) located between the upper platform (31) and the lower platform (32); The bionic snail member (30) includes an upper planar portion, a lower planar portion, an annular portion and a V-shaped portion located between the upper planar portion and the lower planar portion; the upper planar portion is connected to the upper platform (31), and the lower planar portion is connected to the lower platform (32); the bottom of the annular portion is connected to the lower planar portion and the top of the annular portion has an opening, and the two branches of the V-shaped portion are connected to both ends of the opening of the annular portion and the two branches extend upward and are connected to the upper planar portion; The upper flexible electrode (1) and the lower flexible electrode (2) are respectively located on one side surface of the upper platform (31) and the lower platform (32) away from the bionic snail member (30).

2. The capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail according to claim 1, characterized in that, There are through holes in the middle of the upper flexible electrode (1) and / or the lower flexible electrode (2); Preferably, the upper flexible electrode (1) and / or the lower flexible electrode (2) is a square annular electrode with a square through hole in the middle, and the ratio of the outer side length a to the inner side length b of the square annular electrode is 4:3; Preferably, the upper flexible electrode (1) and the lower flexible electrode (2) are conductive fabrics.

3. The capacitive proximity-pressure dual-functional flexible sensor based on bionic snails according to claim 1 or 2, characterized in that The included angle θ between the two branches of the V-shaped portion is 25°, and the ratio of the radius r of the annular portion to the distance h from the top of the annular portion to the upper planar portion is 3:

2.

4. The capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail according to any one of claims 1-3, characterized in that It also includes an upper encapsulation layer (4) and a lower encapsulation layer (5); The upper encapsulation layer (4) and the lower encapsulation layer (5) are respectively located on one side surface of the upper flexible electrode (1) and the lower flexible electrode (2) away from the elastic structural member (3), and encapsulate the upper flexible electrode (1) and the lower flexible electrode (2); Preferably, the sizes of the upper encapsulation layer (4) and the lower encapsulation layer (5) are respectively the same as those of the upper flexible electrode (1) and the lower flexible electrode (2).

5. The capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail according to claim 4, wherein The upper encapsulation layer (4) and the lower encapsulation layer (5) are polyimide film layers.

6. The capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail according to any one of claims 1-5, characterized in that, The number of the bionic snail members (30) is four.

7. A preparation method of a capacitive proximity-pressure dual-functional flexible sensor based on a bionic snail, characterized in that, It includes the following steps: S1. Add a PDMS solution into a mold with a preset inner cavity shape and cure it. After peeling, a bionic snail member is obtained. The bionic snail member includes an upper planar portion, a lower planar portion, an annular portion and a V-shaped portion located between the upper planar portion and the lower planar portion. The bottom of the annular portion is connected to the lower planar portion and the top of the annular portion has an opening, and the two branches of the V-shaped portion are connected to both ends of the opening of the annular portion and the two branches extend upward and are connected to the upper planar portion; S2. Connect the upper planar portions and the lower planar portions of a number of bionic snail members to two PDMS film layers serving as the upper platform and the lower platform respectively to obtain an elastic structural member. The elastic structural member includes an upper platform, a lower platform and a number of bionic snail members located between the upper platform and the lower platform; S3. Laminate two conductive fabrics as the upper flexible electrode and the lower flexible electrode respectively onto one side surface of the two PDMS film layers serving as the upper platform and the lower platform away from the bionic snail member, and then the capacitive proximity-pressure dual-functional sensor is obtained.

8. The preparation method of the bionic snail-based capacitive proximity-pressure dual-functional flexible sensor according to claim 7, characterized in that, In step S1, the main component A of PDMS and the curing agent B are mixed at a mass ratio of 10:1 as the PDMS solution; Preferably, the curing temperature is 40 - 60 °C and the time is 4 - 8 h.

9. The preparation method of the bionic snail-based capacitive proximity-pressure dual-functional flexible sensor according to claim 7 or 8, characterized in that In step S2, a conductive fabric serving as the upper flexible electrode and / or the lower flexible electrode is cut by a blade die under the action of a die-cutting machine to form a square annular electrode with a square through-hole in the center of the square annular electrode.

10. The preparation method of the bionic snail-based capacitive proximity-pressure dual-functional flexible sensor according to any one of claims 7-9, characterized in that, In step S3, it further includes laminating two polyimide film layers as the upper encapsulation layer and the lower encapsulation layer to the surfaces of the two conductive fabrics serving as the upper flexible electrode and the lower flexible electrode, which are away from the elastic structural member, respectively.

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