Preparation method of self-repairing conductive composite material and homogeneous integrated flexible capacitive pressure sensor, and flexible robot

Abstract

The invention discloses a preparation method of a self-repairing conductive composite material and a homogeneous integrated flexible capacitive pressure sensor, and a flexible robot, and relates to the technical field of self-repairing materials. Amino groups of amino-terminated polydimethylsiloxane and aldehyde groups from 4, 4 '-dithiodiacyldibenzaldehyde and 1, 4-phthalaldehyde are subjected to a Schiff base reaction to form imine bonds, and meanwhile, disulfide bonds are introduced through the 4, 4'-dithiodiacyldibenzaldehyde, so that a dynamic cross-linked network is established on the basis of the synergistic effect of the imine bonds and the disulfide bonds; according to the self-repairing conductive composite material disclosed by the invention, the self-repairing capability of the material is promoted, and effective self-repairing in various complex environments such as room temperature, freezing environment, heating environment, water and salt solution is realized; the problem of low signal repairing efficiency caused by the problem that healing kinetics of all layers of materials of a multi-layer heterostructure sensor are not matched can be solved.

Description

Technical Field

[0001] This invention relates to the field of self-healing materials technology, and in particular to a method for preparing a self-healing conductive composite material and a homogeneous integrated flexible capacitive pressure sensor, as well as a flexible robot. Background Technology

[0002] In recent years, the rapid development of flexible robots and wearable devices has driven a growing demand for high-performance flexible pressure sensors. As a core component for robots to perceive and interact with their external environment, the reliability of pressure sensors directly affects the accuracy with which robots identify the pressure properties of objects.

[0003] Pressure sensors often face the dual challenges of mechanical loads and extreme environments in practical applications. Long-term dynamic pressure can easily cause scratches, cracks, and wear on the sensor's functional layers. Furthermore, contact with sharp objects (such as knives or needles) or exposure to extreme working environments like low temperatures or underwater environments can lead to sudden damage. This damage not only degrades the mechanical properties of the materials but also causes performance failures such as signal drift and decreased sensitivity, severely impacting the accuracy and stability of the pressure sensor's sensing signal. When a pressure sensor fails due to damage, traditional repair methods involve manual repairs such as adhesive bonding or module replacement. However, these methods interrupt the work process, increasing repair and time costs, and therefore have limitations. In working environments such as the field or deep sea where manual on-site repair is difficult, these conventional repair methods are also impractical, seriously affecting the long-term reliability of remote or autonomous robots.

[0004] Therefore, developing flexible pressure sensors with self-healing capabilities is crucial to ensuring their reliable performance and long-term durability. Summary of the Invention

[0005] The main objective of this invention is to propose a method for preparing a self-healing conductive composite material and a homogeneous integrated flexible capacitive pressure sensor, as well as a flexible robot, in order to solve the problem that existing flexible pressure sensors are difficult to repair in various complex environments.

[0006] To achieve the above objectives, this invention proposes a method for preparing a self-healing matrix material, comprising the following steps: The amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde and solvent are dispersed to obtain a raw material dispersion. The raw material dispersion is heated to cause the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylformaldehyde to undergo a crosslinking reaction to obtain an intermediate. 1,4-Benzaldehyde and a solvent are mixed to form a 1,4-Benzaldehyde solution. The 1,4-Benzaldehyde solution is then added to the intermediate and stirred until a first gel is formed. The first gel is then dried to obtain the self-healing matrix material.

[0007] In one embodiment, the mass ratio of the amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylcarboxaldehyde, and 1,4-phenylcarboxaldehyde is 5000:(10~40):(20~35); and / or, The step of dispersing amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde, and a solvent to obtain a raw material dispersion includes: first, mixing the amino-terminated polydimethylsiloxane and the solvent to form a polydimethylsiloxane solution; then, adding 4,4'-dithiodiphenylformaldehyde to the amino-terminated polydimethylsiloxane solution and ultrasonically dispersing it to obtain the raw material dispersion; and / or, The raw material dispersion is heated at 85-95°C for 2-3 hours.

[0008] The present invention also proposes a self-healing matrix material, wherein the self-healing matrix material comprises a self-healing matrix material prepared by the preparation method of the self-healing matrix material described in the foregoing technical solution.

[0009] This invention also proposes a method for preparing a self-healing conductive composite material, comprising the following steps: The amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde and solvent are dispersed to obtain a raw material dispersion. The raw material dispersion is heated to cause the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylformaldehyde to undergo a crosslinking reaction to obtain an intermediate. The intermediate and the conductive material are mixed and then ultrasonically dispersed in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material. 1,4-Benzaldehyde and a solvent are mixed to form a 1,4-Benzaldehyde solution. The 1,4-Benzaldehyde solution is added to the dispersion containing the intermediate and conductive material, and the mixture is stirred until a second gel is formed. The second gel is then dried to obtain the self-healing conductive composite material.

[0010] In one embodiment, the mass ratio of the amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylcarboxaldehyde, and 1,4-phenylcarboxaldehyde is 5000:(10~40):(20~35); and / or, The raw material dispersion is heated at 85-95°C for 2-3 hours; and / or, The ultrasonic dispersion treatment in an ice-water bath was carried out for 2 hours; and / or; The conductive material includes a conductive polymer and a carbon-based material, wherein the conductive polymer includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, and the carbon-based material includes carbon nanotubes.

[0011] In one embodiment, the conductive material comprises poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes: The mass ratio of the amino-terminated polydimethylsiloxane, carbon nanotubes, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is 1:(0.02~0.07):(0.10~0.40); and / or, The step of mixing the intermediate and the conductive material and performing ultrasonic dispersion treatment in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material includes: mixing the intermediate, the conductive material, the nonionic surfactant and the solvent, and performing ultrasonic dispersion treatment in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material.

[0012] The present invention also proposes a self-healing conductive composite material, wherein the self-healing conductive composite material comprises a self-healing conductive composite material prepared by the preparation method of the self-healing conductive composite material described in the foregoing technical solution.

[0013] The present invention also proposes a homogeneous integrated flexible capacitive pressure sensor, comprising a dielectric layer and electrode layers disposed on both sides of the dielectric layer, wherein: The electrode layer includes a first self-healing conductive composite material, which is prepared by the preparation method described in the aforementioned technical solution. The conductive material in the first self-healing conductive composite material includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes. In the first self-healing conductive composite material, the mass ratio of carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is (0.05~0.07):0.25. The dielectric layer includes a second self-healing conductive composite material, which is prepared by the preparation method described in the aforementioned technical solution. The conductive material in the second self-healing conductive composite material includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes. In the second self-healing conductive composite material, the mass ratio of carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is (0.02~0.03):0.25.

[0014] This invention proposes a method for fabricating a homogeneous integrated flexible capacitive pressure sensor as described in the aforementioned technical solution, comprising the following steps: A first self-healing conductive composite material and a second self-healing conductive composite material are provided. The first self-healing conductive composite material and the second self-healing conductive composite material are hot-pressed respectively to obtain an electrode layer precursor and a dielectric layer precursor. Microstructures were constructed on the surface of the dielectric layer precursor using 3D printing technology to obtain a dielectric layer precursor with microstructures. The two electrode layer precursors and the two dielectric layer precursors with microstructures are stacked sequentially, wherein the two electrode layer precursors are located on the outermost side, and the two dielectric layer precursors with microstructures are located on the inner side and opposite to each other, forming a stacked structure of "electrode layer / dielectric layer / dielectric layer / electrode layer". The stacked structure is left to stand, allowing the layers to fuse through self-healing, resulting in the homogeneous integrated flexible capacitive pressure sensor.

[0015] This invention proposes a flexible robot, which includes the homogeneous integrated flexible capacitive pressure sensor described in the foregoing technical solution, or the homogeneous integrated flexible capacitive pressure sensor prepared by the preparation method described in the foregoing technical solution.

[0016] The technical solution of the present invention has the following beneficial effects: (1) This invention provides a method for preparing a self-healing matrix material, using amino-terminated polydimethylsiloxane (PDMS-NH2) as the main raw material, and adding 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) and 1,4-phenylcarboxaldehyde (DFB) as crosslinking agents. The amino groups on the side chains of the amino-terminated polydimethylsiloxane react with the aldehyde groups from 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) and 1,4-phenylcarboxaldehyde (DFB) to form imine bonds, thereby establishing a dynamic crosslinking network. Furthermore, 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) also contains disulfide bonds, which can further promote the self-healing ability of the material through dynamic bond exchange. Therefore, the self-healing matrix material provided by this invention can achieve effective self-healing in various complex environments such as room temperature, freezing environment, heating environment, water and salt solution based on the synergistic effect of multiple dynamic bonds (imine bond and disulfide bond), laying the foundation for the fabrication of sensors and flexible robots that can achieve repair in complex environments. At the same time, the self-healing material provided by this invention also has the characteristic of being reprocessable, which helps to reduce production cost input and facilitates large-scale factory production.

[0017] (2) This invention provides a self-healing conductive composite material and its preparation method. Amino-terminated polydimethylsiloxane (PDMS-NH2) is used as the main self-healing material raw material, and 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) and 1,4-phenylcarboxaldehyde (DFB) are added as crosslinking agents. The amino groups on the side chains of the amino-terminated polydimethylsiloxane react with the aldehyde groups from 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) and 1,4-phenylcarboxaldehyde (DFB) to form imine bonds, thereby establishing a dynamic crosslinking network. Simultaneously, the introduction of disulfide bonds using 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) further promotes the material's self-healing ability through dynamic bond exchange. Furthermore, since conductive materials are also added to the self-healing conductive composite material, the resulting self-healing conductive elastomer, after self-healing from damage, possesses not only mechanical self-healing ability but also electrical self-healing ability. The self-healing conductive composite material provided by this invention can achieve effective self-repair under various complex environments such as room temperature, freezing environment, heating environment, water and salt solution, based on the synergistic effect of multiple dynamic bonds (imine bond and disulfide bond).

[0018] (3) Based on the provided self-healing conductive composite material, this invention provides a homogeneous integrated flexible capacitive pressure sensor and its fabrication method. The homogeneous integrated flexible capacitive pressure sensor includes a dielectric layer and electrode layers disposed on both sides of the dielectric layer. In the technical solution of this invention, since the materials of the dielectric layer and the electrode layer are both based on the same self-healing conductive composite material, the difference lies in the different proportions of conductive fillers contained in the dielectric layer and the electrode layer, thus facilitating the fabrication of a self-healing sensor with a homogeneous integrated structure. At the same time, since the self-healing conductive composite material used can achieve effective self-repair under various complex environments such as room temperature, freezing environment, heating environment, water, and salt solution based on the synergistic effect of multiple dynamic bonds (imine bonds and disulfide bonds), the homogeneous integrated flexible capacitive pressure sensor provided by this invention can be used to solve the problem of low signal repair efficiency caused by the mismatch of healing kinetics of each layer material in traditional multilayer heterogeneous structure sensors. Attached Figure Description

[0019] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the preparation of the self-healing matrix material in Example 1; Figure 2 The FT-IR spectra of the self-healing PDMS elastomer and amino-terminated polydimethylsiloxane of Example 1 are shown below. Figure 3 This is a graph showing the test results of the self-healing function of the self-healing PDMS elastomer in Example 1 at room temperature; Figure 4 The image shows optical microscope comparisons of the self-healing PDMS elastomer of Example 1 after crack self-healing at room temperature for 0 h, 2 h, 4 h, 8 h, and 12 h. Figure 5 The optical microscope images show the self-healing PDMS elastomer of Comparative Example 1 after cutting at room temperature for 0 h and 24 h to self-heal the crack. Figure 6 The stress-strain curves of the self-healing PDMS elastomer of Example 1 after self-healing for different times at room temperature are shown, wherein the tensile speed when stress is applied is 15 mm / min. Figure 7 The stress-strain curves of the self-healing PDMS elastomer of the original embodiment 1 and the reprocessed self-healing PDMS elastomer are shown, wherein the tensile speed when stress is applied is 15 mm / min. Figure 8 The graph shows the self-healing efficiency of the self-healing PDMS elastomer in Example 1 under conditions of -15°C, room temperature, 40°C, underwater, and salt solution. The tensile speed under applied stress is 15 mm / min. Figure 9 The images show optical microscopy comparisons of the self-healing PDMS elastomer of Example 1 immediately after damage and after 24 hours of repair at -15°C. Figure 10 This is a graph showing the test results of the self-healing conductive elastomer of Example 2 at room temperature; Figure 11 The graph shows the resistance change of the self-healing conductive elastomer in Example 3 during the self-healing process. Figure 12 Figure showing the self-healing efficiency of self-healing conductive elastomers with different CNT contents at room temperature; Figure 13 The graph shows the test results of the self-healing conductive elastomer of Example 2 under the condition of -15℃. Figure 14 The graph shows the test results of the self-healing conductive elastomer in water in Example 2. Figure 15 The graph shows the electrical signal repair test results of the self-healing conductive elastomer in water in Example 3. Figure 16This is a schematic diagram of the dielectric layer precursor with microstructure prepared in Example 4; Figure 17 This is a SEM image of the dielectric layer precursor with microstructure in Example 4; Figure 18 This is a schematic diagram of the structure of the homogeneous integrated flexible capacitive pressure sensor in Example 4; Figure 19 The figure shows the test results of the self-healing function of the homogeneous integrated flexible capacitive pressure sensor in Example 4 at room temperature. Figure 20 The graph shows the relative capacitance of the homogeneous integrated flexible capacitive pressure sensor in Example 4 before wear and after 12 hours of self-repair as a function of pressure. Figure 21 The graphs show the response and recovery time of the homogeneous integrated flexible capacitive pressure sensor in Example 4 before wear and after 12 hours. Figure 22 The graph shows the cycle stability test results of the homogeneous integrated flexible capacitive pressure sensor in Example 4 before wear and after 12 hours, where the applied pressure is 10 kPa. Figure 23 The graph shows the relative capacitance of the homogeneous integrated flexible capacitive pressure sensor of Example 4, placed in water, before wear and after self-repair, as a result of time. Figure 24 The image shows the signal change results of a flexible robot, which includes the homogeneous integrated flexible capacitive pressure sensor of Example 4, during the process of grasping a doll. Figure 25 The image shows the signal change results of a flexible robot, which includes the homogeneous integrated flexible capacitive pressure sensor of Example 4, during the process of grasping a cactus. Figure 26 The mechanical gripper, which includes the homogeneous integrated flexible capacitive pressure sensor of Example 4, shows the signal response results before wear, during damage, and after self-repair. Figure 27 This is a graph showing the results of the sensor signal restoration test of the homogeneous integrated flexible capacitive pressure sensor in water in Example 4.

[0021] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0022] 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 a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0023] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0024] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0025] Currently, based on different repair mechanisms, self-healing materials are mainly divided into exogenous and intrinsic types. Exogenous self-healing achieves repair by releasing repair agents through pre-embedded microcapsules or microvascular networks, but it suffers from limitations in the number of repair cycles. In contrast, intrinsic self-healing utilizes the spontaneous recombination properties of reversible dynamic chemical bonds (such as hydrogen bonds and disulfide bonds) within the material, enabling multiple self-repairs at the molecular level and exhibiting excellent repair sustainability. However, achieving autonomous self-healing under harsh conditions such as underwater and low-temperature environments remains challenging. Extreme environments severely restrict the self-healing performance of materials. For example, low temperatures significantly reduce the mobility of molecular chain segments, inhibiting the reversible recombination process of dynamic bonds; water molecules in underwater environments compete with dynamic interaction sites such as hydrogen bonds and metal coordination bonds in the material, hindering the dynamic self-healing process at the damaged interface.

[0026] Furthermore, in soft pressure sensors, self-healing polymers are often mixed with conductive fillers to impart conductivity. The addition of such fillers further hinders the reformation of dynamic bonds and the rearrangement of polymer chains, thus suppressing the self-healing capability. Moreover, although various high-performance self-healing materials have been developed, their application in flexible pressure sensors, especially those with multilayer structures, is often accompanied by poor healing efficiency due to inconsistent healing rates. This can lead to residual stress and even delamination at the interface. Therefore, developing self-healing pressure sensors capable of recovering mechanical and electrical properties under harsh environmental conditions remains a significant challenge.

[0027] Based on the above background, please refer to Figure 1 This invention proposes a method for preparing a self-healing matrix material, comprising the following steps: A1. The amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde and solvent are dispersed to obtain a raw material dispersion. The raw material dispersion is heated to cause the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylformaldehyde to undergo a crosslinking reaction to obtain an intermediate. A2. Mix 1,4-benzaldehyde and a solvent to form a 1,4-benzaldehyde solution, then add the 1,4-benzaldehyde solution to the intermediate and stir until a first gel is formed. Dry the first gel to obtain the self-healing matrix material.

[0028] In the technical solution of this invention, amino-terminated polydimethylsiloxane (PDMS-NH2) is used as the main raw material, and 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) and 1,4-phenylcarboxaldehyde (DFB) are added as crosslinking agents. The amino groups on the side chains of the amino-terminated polydimethylsiloxane react with the aldehyde groups from 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) and 1,4-phenylcarboxaldehyde (DFB) to form imine bonds, thereby establishing a dynamic crosslinking network. Furthermore, 4,4'-dithiodiphenylcarboxaldehyde (SS-CHO) also contains disulfide bonds, which can further promote the self-healing ability of the material through dynamic bond exchange. Therefore, the self-healing matrix material provided by this invention achieves effective self-healing in various complex environments such as room temperature, freezing environment, heating environment, water and salt solution based on the synergistic effect of multiple dynamic bonds (imine bond and disulfide bond). This lays the foundation for the fabrication of sensors and flexible robots that can achieve self-healing in complex environments. At the same time, the self-healing material has the characteristic of being reprocessable, which helps to reduce production cost input and is suitable for large-scale factory production.

[0029] It should be noted that, considering the slow crosslinking speed of SS-CHO and PDMS-NH2, and the rapid formation of an organic gel after the addition of DFB, directly mixing the three would not allow SS-CHO to react sufficiently. Therefore, the technical solution of this invention selects to first perform a crosslinking reaction between PDMS-NH2 and 4,4'-dithiodiphenylcarbaldehyde, and then add 1,4-phenylcarbaldehyde to continue the reaction to form a gel. Furthermore, the inventors found that if only 4,4'-dithiodiphenylcarbaldehyde is used without 1,4-phenylcarbaldehyde, a gel material cannot be formed; if only 1,4-phenylcarbaldehyde is used, although an organic gel can be synthesized to obtain a polymer with self-healing function, its self-healing effect at room temperature is observed to be inferior to that of the self-healing matrix material prepared by simultaneously adding 4,4'-dithiodiphenylcarbaldehyde and 1,4-phenylcarbaldehyde. Therefore, this invention selects amino-modified polydimethylsiloxane, 4,4'-dithiodiphenylcarbaldehyde, and 1,4-phenylcarbaldehyde as raw materials.

[0030] In an embodiment of the present invention, the mass ratio of the amino-terminated polydimethylsiloxane, 4,4'-dithiodibenzoylmethane and 1,4-benzaldehyde is 5000:(10~40):(20~35).

[0031] If the amount of 4,4'-dithiodiphenylformaldehyde is too small or too large, the self-healing efficiency of the prepared self-healing matrix material at room temperature will be significantly reduced. If the amount of 1,4-phenylenedialdehyde is too small or too large, an organic gel cannot be formed.

[0032] In an embodiment of the present invention, step A1, wherein the step of dispersing amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde and solvent to obtain a raw material dispersion includes: First, amino-terminated polydimethylsiloxane and solvent are mixed to form a polydimethylsiloxane solution. Then, 4,4'-dithiodiphenylcarboxaldehyde is added to the amino-terminated polydimethylsiloxane solution and ultrasonically dispersed to obtain a raw material dispersion.

[0033] The inventors discovered that amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylformaldehyde are difficult to disperse uniformly using conventional mechanical stirring. Therefore, in the technical solution of this invention, ultrasonic dispersion is used to obtain the raw material dispersion. In one embodiment of this invention, the ultrasonic dispersion is performed using a cell disruptor with parameters of "120 W, 4 s on, 4 s off", and the ultrasonic dispersion time is 5 min.

[0034] In an embodiment of the present invention, in step A1, the raw material dispersion is heated at 85-95°C for 2-3 hours. Exemplarily, the raw material dispersion can be heated at 85°C, 90°C, or 95°C for 2 hours, 2.5 hours, or 3 hours.

[0035] It should be noted that the self-healing matrix material obtained in step A2 is an irregular, amorphous material. To facilitate its use in specific applications, after completing step A2, the prepared material can be placed between gaskets with a polytetrafluoroethylene film and hot-pressed at room temperature using a hot press to obtain a self-healing elastomer. In one embodiment of the present invention, after obtaining the self-healing matrix material, it is further pressed at 500N at room temperature for 12 hours to obtain the self-healing elastomer.

[0036] The present invention also proposes a self-healing matrix material, wherein the self-healing matrix material comprises a self-healing matrix material prepared by the preparation method of the self-healing matrix material described in the foregoing technical solution.

[0037] This invention proposes a method for preparing a self-healing conductive composite material, comprising the following steps: B1. The amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde and solvent are mixed and dispersed to obtain a raw material dispersion. The raw material dispersion is heated to cause the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylformaldehyde to undergo a crosslinking reaction to obtain an intermediate. B2. The intermediate and the conductive material are mixed and ultrasonically dispersed in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material; B3. Mix 1,4-benzaldehyde and a solvent to form a 1,4-benzaldehyde solution. Add the 1,4-benzaldehyde solution to the dispersion containing the intermediate and conductive material, and stir until a second gel is formed. Dry the second gel to obtain the self-healing conductive composite material.

[0038] In an embodiment of the present invention, in step B1, the mass ratio of the amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde, and 1,4-phenylenedialdehyde is 5000:(10~40):(20~35). Setting the amounts of amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde, and 1,4-phenylenedialdehyde within the above range is beneficial for obtaining a self-healing conductive composite material with self-healing functions under various complex environments such as room temperature, freezing conditions, heating conditions, water, and salt solutions.

[0039] In an embodiment of the present invention, step B1, which involves dispersing the amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde, and solvent to obtain a raw material dispersion, includes: First, amino-terminated polydimethylsiloxane and solvent are mixed to form a polydimethylsiloxane solution. Then, 4,4'-dithiodiphenylcarboxaldehyde is added to the amino-terminated polydimethylsiloxane solution and ultrasonically dispersed to obtain a raw material dispersion.

[0040] In an embodiment of the present invention, in step B1, the raw material dispersion is heated at 85-95°C for 2-3 hours. Exemplarily, the raw material dispersion can be heated at 85°C, 90°C, or 95°C for 2 hours, 2.5 hours, or 3 hours.

[0041] In an embodiment of the present invention, in step B2, the ultrasonic dispersion treatment in an ice-water bath is carried out for 2 hours.

[0042] In embodiments of the present invention, the conductive material includes a conductive polymer and a carbon-based material, wherein the conductive polymer includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), and the carbon-based material includes carbon nanotubes (CNTs).

[0043] The inventors discovered that using only PEDOT:PSS as a conductive material results in a non-conductive material that cannot achieve self-healing electrical properties. Using only carbon-based materials (such as carbon nanotubes, graphene, and MXene) requires extensive carbon doping, but this doping (such as CNTs) negatively impacts the elastomer's self-healing efficiency. Furthermore, while higher CNT content improves conductivity, it reduces self-healing efficiency. However, using both PEDOT:PSS and CNTs as conductive fillers, the introduction of PEDOT:PSS introduces hydrogen bonds, mitigating the reduced self-healing efficiency caused by high CNT content. This results in a self-healing conductive composite material that combines excellent self-healing efficiency with good conductivity.

[0044] In an embodiment of the present invention, in step B2, the conductive material comprises poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes, wherein the mass ratio of the amino-terminated polydimethylsiloxane, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, and carbon nanotubes is 1:(0.02~0.07):(0.10~0.40). Preferably, the mass ratio of the amino-terminated polydimethylsiloxane, poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, and carbon nanotubes is 1:(0.03~0.07):0.25.

[0045] In an embodiment of the present invention, step B2, the conductive material comprises poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes, wherein the intermediate and the conductive material are mixed and ultrasonically dispersed in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material, the step comprising: A conductive material, a nonionic surfactant, and a solvent are added to the intermediate, and the mixture is ultrasonically dispersed in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material.

[0046] When PEDOT:PSS and carbon nanotubes are used simultaneously as conductive materials, a small amount of nonionic surfactant needs to be added to improve the wettability of the PEDOT:PSS aqueous dispersion. In one embodiment of the invention, Triton [surfactant name missing] is added... TM X-100 improves the wettability of PEDOT:PSS aqueous dispersion and promotes the dispersion of PEDOT:PSS in the raw material system.

[0047] For the same reason, the self-healing conductive composite material obtained after step B3 is an irregular, amorphous material. To facilitate use in specific applications, after completing step B3, the prepared material can be placed between gaskets with a polytetrafluoroethylene film and hot-pressed at room temperature using a hot press to obtain a self-healing conductive elastomer. In one embodiment of the invention, after obtaining the self-healing conductive composite material, it is pressed at 500N at room temperature for 12 hours to obtain the self-healing conductive elastomer.

[0048] The present invention also proposes a self-healing conductive composite material, wherein the self-healing conductive composite material comprises a self-healing conductive composite material prepared by the preparation method of the self-healing conductive composite material described in the foregoing technical solution.

[0049] The present invention also proposes a homogeneous integrated flexible capacitive pressure sensor, comprising a dielectric layer and electrode layers disposed on both sides of the dielectric layer, wherein: The electrode layer includes a first self-healing conductive composite material, which is prepared by the preparation method described in the aforementioned technical solution. The conductive material in the first self-healing conductive composite material includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes. In the first self-healing conductive composite material, the mass ratio of carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is (0.05~0.07):0.25. The dielectric layer includes a second self-healing conductive composite material, which adopts the self-healing conductive composite material described in the aforementioned technical solution. The conductive material in the second self-healing conductive composite material includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes. In the second self-healing conductive composite material, the mass ratio of the carbon nanotubes to the poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is (0.02~0.03):0.25.

[0050] Conventional sensors typically lack self-healing capabilities. While some self-healing sensors have been reported, most operate at room temperature or low temperatures, making them unsuitable for use in harsh real-world environments. Furthermore, reported self-healing sensors often use different materials for each layer. The present invention addresses this by using the same self-healing conductive composite material for both the dielectric and electrode layers, differing only in the proportion of conductive fillers. This facilitates the fabrication of a homogeneous, integrated self-healing sensor. Moreover, the self-healing conductive composite material enables effective self-healing under various complex environments, including room temperature, freezing, heating, water, and salt solutions, through the synergistic effect of multiple dynamic bonds (imine and disulfide bonds). Therefore, the homogeneous, integrated flexible capacitive pressure sensor provided by this invention can solve the problem of low signal repair efficiency caused by the mismatch in healing kinetics between layers in traditional multilayer heterogeneous sensors.

[0051] In one embodiment of the present invention, in the first self-healing conductive composite material, the mass ratio of carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is 0.06:0.25; in the second self-healing conductive composite material, the mass ratio of carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is 0.03:0.25. By setting the ratio of the two conductive materials in the first and second self-healing conductive composite materials within the above range, a homogeneous integrated flexible capacitive pressure sensor that combines conductivity, good signal response, and satisfactory self-healing efficiency can be obtained.

[0052] This invention also proposes a method for fabricating the homogeneous integrated flexible capacitive pressure sensor described in the foregoing technical solution, comprising the following steps: C1. Provide a first self-healing conductive composite material and a second self-healing conductive composite material, and hot-press the first self-healing conductive composite material and the second self-healing conductive composite material respectively to obtain an electrode layer precursor and a dielectric layer precursor. C2. Microstructures are constructed on the surface of the dielectric layer precursor using 3D printing technology to obtain a dielectric layer precursor with microstructures. C3. Stack the two electrode layer precursors and the two dielectric layer precursors with microstructures in sequence, wherein the two electrode layer precursors are located on the outermost side and the two dielectric layer precursors with microstructures are located on the inner side and opposite to each other, forming a stacked structure of "electrode layer / dielectric layer / dielectric layer / electrode layer". C4. The stacked structure is left to stand still, allowing the layers to fuse through self-healing, resulting in the homogeneous integrated flexible capacitive pressure sensor.

[0053] In the technical solution of this invention, the first and second self-healing conductive composite materials are first pre-shaped by hot pressing to obtain an electrode layer precursor and a dielectric layer precursor. Then, microstructures are printed on the surface of the dielectric layer precursor to obtain a dielectric layer precursor with microstructures. Next, the electrode layer precursor and the dielectric layer precursor with microstructures are stacked sequentially, allowing the layers to fuse through self-healing, thus obtaining a homogeneous, integrated flexible capacitive pressure sensor. Using the above technical solution, a capacitive flexible pressure sensor with a homogeneous, integrated structure can be obtained, solving the problem of low signal repair efficiency caused by the mismatch in healing kinetics between layers in traditional multilayer heterogeneous structure sensors.

[0054] It should be noted that introducing microstructures onto the surface of the dielectric layer can generate larger reversible deformation under pressure, significantly enhancing the capacitance change and thus improving the sensor's response capability (i.e., sensitivity) to minute pressures. Furthermore, the microstructures can modulate the nonlinear characteristics of the pressure-capacitance response curve, helping to maintain good linear or controllable nonlinear response over a wide pressure range, thereby improving the sensor's response range.

[0055] This invention proposes a flexible robot, which includes the homogeneous integrated flexible capacitive pressure sensor described in the foregoing technical solutions, or the homogeneous integrated flexible capacitive pressure sensor prepared by the preparation method described in the foregoing technical solutions. Since the flexible robot incorporates all the technical solutions of the homogeneous integrated flexible capacitive pressure sensor, it possesses all the beneficial effects of the homogeneous integrated flexible capacitive pressure sensor, which will not be elaborated upon here.

[0056] The technical solution of the present invention will be further described in detail below with reference to specific embodiments and accompanying drawings. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0057] Example 1 A method for preparing a self-healing matrix material includes the following steps: (1) 5 g of amino-terminated polydimethylsiloxane (PDMS-NH2) and 15 mL of toluene were stirred with a magnetic stirrer for 20 min at room temperature to form a PDMS-NH2 solution. 20 mg of 4,4'-dithiodiphenylcarboxaldehyde was added to the PDMS-NH2 solution, and then the mixture was ultrasonically dispersed for 5 min (120 W, 4 s on, 4 s off) using a cell disruptor to obtain a raw material dispersion. The above raw material dispersion was continuously stirred at 85 °C (oil bath heating) for 3 h to allow the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylcarboxaldehyde to undergo a crosslinking reaction to obtain an intermediate.

[0058] (2) 250 mg of 1,4-phenylenedialdehyde and 25 mL of toluene were stirred with a magnetic stirrer for 20 min at room temperature to form a 1,4-phenylenedialdehyde solution. 3 mL of the 1,4-phenylenedialdehyde solution was added to the intermediate obtained in step (1), and stirring was continued until the first gel was obtained. The first gel was placed in a vacuum environment and dried at 60 °C for 24 h to remove residual solvent, thus obtaining the self-healing matrix material.

[0059] (3) Place the self-healing matrix material between the gaskets with polytetrafluoroethylene film, and press it at 500 N for 12 h at room temperature using a hot press to obtain the self-healing PDMS elastomer.

[0060] Example 2 A method for preparing a self-healing conductive composite material includes the following steps: (1) 5 g of amino-terminated polydimethylsiloxane (PDMS-NH2) and 15 mL of toluene were stirred with a magnetic stirrer for 20 min at room temperature to form a PDMS-NH2 solution. 20 mg of 4,4'-dithiodiphenylcarboxaldehyde was added to the PDMS-NH2 solution, and then the mixture was ultrasonically dispersed for 5 min (120 W, 4 s on, 4 s off) using a cell disruptor to obtain a raw material dispersion. The above raw material dispersion was continuously stirred at 85 °C (oil bath heating) for 3 h to allow the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylcarboxaldehyde to undergo a crosslinking reaction to obtain an intermediate.

[0061] (2) 150 mg carbon nanotubes, 1.25 g PEDOT:PSS, 0.4 g Triton™ X-100 and 20 mL toluene were added to the intermediate and ultrasonically dispersed in an ice-water bath for 2 h using a cell disruptor (120 W, 4 son, 4 s off) to obtain a dispersion containing the intermediate and conductive material.

[0062] (3) 250 mg of 1,4-phenylenedialdehyde and 25 mL of toluene were stirred with a magnetic stirrer for 20 min at room temperature to form a 1,4-phenylenedialdehyde solution. 3 mL of the 1,4-phenylenedialdehyde solution was added to the above dispersion containing the intermediate and conductive material, and the mixture was stirred continuously until a second gel was obtained. The second gel was placed in a vacuum environment and dried at 60 °C for 24 h to remove residual solvent, thus obtaining a self-healing conductive composite material.

[0063] (4) Place the self-healing conductive composite material prepared in step (3) between the gaskets with polytetrafluoroethylene film, and press it at 500 N for 12 h at room temperature using a hot press to obtain the self-healing PDMS / CNT / PEDOT:PSS composite material (also referred to as self-healing conductive elastomer).

[0064] Example 3 The difference compared to Example 1 is that the amount of carbon nanotubes used is 300 mg.

[0065] Example 4 A homogeneous, integrated flexible capacitive pressure sensor includes a dielectric layer and electrode layers disposed on both sides of the dielectric layer. The electrode layers include a first self-healing conductive composite material, and the dielectric layer includes a second self-healing conductive composite material, wherein: In the first self-healing conductive composite material, the mass ratio of carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is 6:25; In the second self-healing conductive composite material, the mass ratio of the carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is 3:25; The method for fabricating the homogeneous integrated flexible capacitive pressure sensor includes the following steps: (1) The first self-healing conductive composite material was prepared according to the method of Example 3, and the first self-healing conductive composite material was hot-pressed to obtain the electrode layer precursor; (2) The second self-healing conductive composite material was prepared according to the method of Example 2, and the second self-healing conductive composite material was hot-pressed to obtain the dielectric layer precursor; (3) such as Figure 16 As shown, microstructures are constructed on the surface of the dielectric layer precursor using 3D printing technology to obtain a dielectric layer precursor with microstructures. Figure 17 ); (4) such as Figure 18As shown, two electrode layer precursors and two dielectric layer precursors with microstructures are stacked sequentially, with the two electrode layer precursors located on the outermost side and the two dielectric layer precursors with microstructures located on the inner side and facing each other, forming a stacked structure of "electrode layer / dielectric layer / dielectric layer / electrode layer". (5) The stacked structure is left to stand still, so that the interfaces between the layers can be fused through self-healing, and the homogeneous integrated flexible capacitive pressure sensor is obtained.

[0066] Comparative Example 1 The difference compared to Example 1 is that the amount of 4,4'-dithiodiphenylformaldehyde used is 0.

[0067] Comparative Example 2 The difference compared to Example 1 is that the amount of 1,4-benzaldehyde used is 0.

[0068] Result: Following the steps in Example 1, a gel material could not be formed.

[0069] Comparative Example 3 The difference compared to Example 2 is that the amount of CNT used is 0.

[0070] Result: The prepared material is non-conductive and cannot achieve self-healing of electrical properties.

[0071] Comparative Example 4 The difference compared to Example 2 is that the amount of PEDOT:PSS used is 0.

[0072] Performance testing 1. Self-healing PDMS elastomer: 1) Fourier transform infrared spectroscopy (FT-IR) test: The FT-IR test results of the self-healing PDMS elastomer in Example 1 are as follows: Figure 2 As shown, at 1650~1670 cm -1 and 565 cm -1 Characteristic absorption peaks appeared at the locations, which are due to the stretching vibrations of the C=N bond and the SS bond, indicating that the self-healing matrix material prepared in Example 1 successfully introduced two reversible dynamic bonds, imine bond and disulfide bond.

[0073] 2) Self-healing function test at room temperature: like Figure 3As shown, the rectangular self-healing PDMS elastomer sample prepared in Example 1 was divided in two, and the fracture surfaces were then re-contacted. After 2 hours of repair at room temperature, the re-bonded sample regained sufficient mechanical integrity and was able to withstand various deformations, including bending and torsion. Furthermore, a crack was cut into the rectangular self-healing PDMS elastomer of Example 1, and the self-healing of the cut was observed under an optical microscope. The results of the optical microscope images are shown below. Figure 4 As shown, after 12 hours of self-healing at room temperature, the cut marks on the rectangular self-healing PDMS elastomer were almost completely eliminated. However, in Comparative Example 1, a self-healing PDMS elastomer sample with a cut showed that even after 24 hours of self-healing at room temperature, the crack was still clearly visible. Figure 5 ).

[0074] Furthermore, the self-healing efficiency of the polymer was quantitatively evaluated through mechanical property characterization. In the self-healing test, the original self-healing PDMS elastomer sample was cut into two segments, and the self-healing performance after different times was quantitatively evaluated through mechanical tensile testing. Figure 6 As shown, the tensile strength (stress) of the original sample was 81.2 kPa and the elongation at break (strain) was 329.3%. The sample after 12 h of repair achieved similar mechanical properties, with a tensile strength of 79.6 kPa and an elongation at break of 304.4%. The ratio of the self-healing elongation at break to the original elongation at break was used as the evaluation index for self-healing efficiency. Figure 6 The test results also showed that the self-healing efficiency increased from 12.1% at 15 min to 92.4% at 12 h, indicating that the prepared self-healing PDMS elastomer has excellent self-healing ability at room temperature.

[0075] In addition, the reprocessing performance of the self-healing PDMS elastomer prepared in Example 1 at room temperature was tested. The specific procedure was as follows: the sample was cut into small pieces and placed between gaskets lined with a polytetrafluoroethylene film. After compression molding at room temperature and a pressure of 500 N for 12 h, reprocessed samples were obtained. Mechanical tests were performed on the original samples and the reprocessed samples, such as... Figure 7 As shown in the figure, the results indicate that even after three reprocessing cycles, the mechanical properties of the polymer exhibit minimal change, with the elongation at break remaining at 91.7% of its initial value.

[0076] 3) Self-healing function test under other environments: The self-healing PDMS elastomer prepared in Example 1 was tested under freezing (-15℃), heating (40℃), underwater, and salt solution (35wt% NaCl solution) conditions. The test results are as follows: Figure 8As shown, the self-healing efficiency reached 75.01%±2.83% at sub-zero temperatures (-15℃); 96.12%±1.97% at 40℃; 94.29%±3.67% in water; and 83.76%±4.16% in a 35wt% salt solution.

[0077] Among the self-healing environmental conditions described above, the self-healing efficiency was lowest at -15℃. After storing the sample at -15℃ for 2 hours, the sample was cut and then placed back at -15℃ for self-healing. After 24 hours of self-healing, the cut marks on the sample almost disappeared. Figure 9 This indicates that the prepared self-healing PDMS elastomer has good self-healing properties even under low-temperature conditions.

[0078] The above results show that the self-healing matrix material (self-healing PDMS elastomer) prepared by the present invention has good self-healing effect in various environments.

[0079] 2. Self-healing conductive elastomer: 1) Self-healing function test at room temperature: like Figure 10 As shown, the self-healing conductive elastomer of Example 2 was divided into two halves, and the cross-sections were brought into close contact again and self-healed at room temperature for 12 hours. The repaired self-healing conductive elastomer can withstand bending and torsional deformation.

[0080] Furthermore, the rate of change in resistance of the self-healing conductive elastomer before and after self-healing was tested. For example... Figure 11 As shown, for the self-healing conductive elastomer containing 6 wt% CNT and 25 wt% PEDOT:PSS (Example 3), after the blade completely cuts and restores the point-to-surface interface, the film essentially recovers its electrical signal within 40 s, with a resistance change rate of only 0.56%.

[0081] In addition, the self-healing efficiency of Comparative Example 4 (with only CNTs added to the conductive filler) at room temperature was tested, and the results are as follows: Figure 12 As shown. From Figure 12 It can be seen that without adding PEDOT:PSS, only adding CNT results in low self-healing efficiency of the material, and the higher the CNT content, the worse the self-healing efficiency of the material.

[0082] 2) Self-healing function test under other environments: like Figure 13 and Figure 14As shown, the self-healing conductive elastomer of Example 2 was cut, and the fractured surfaces were reconnected at low temperature (-15°C) and underwater. After 12 hours of self-healing under the corresponding environmental conditions, the conductive elastomer was able to reconnect in both cases. These results indicate that the self-healing conductive elastomer obtained in Example 2 can also withstand temperatures below zero (-15°C). It can achieve self-healing in environments with temperatures of 15℃ and water.

[0083] In addition, the self-healing conductive elastomer of Example 3 (containing 6 wt% CNT and 25 wt% PEDOT:PSS) was connected in series with an LED and placed underwater to test its self-healing effect in water. Figure 15 As shown, the circuit operates at approximately 6.17 V. Before damage, the LED bulb emitted a bright light. After the self-healing conductive elastomer was cut underwater, the light went out. However, after reconnecting the elastomer's broken surface for 12 hours to repair it, the LED bulb emitted light again. These results demonstrate that the self-healing conductive elastomer can restore electrical signals even underwater.

[0084] The above results indicate that, based on a self-healing matrix material with dual dynamic bonds (imine and disulfide bonds), the self-healing PDMS / CNT / PEDOT:PSS composite material (also referred to as a self-healing conductive elastomer) formed by simultaneously doping multi-walled carbon nanotubes (CNTs) and PEDOT:PSS as composite conductive fillers achieves both mechanical self-healing capability and electrical self-healing capability.

[0085] 3. Homogeneous integrated flexible capacitive pressure sensor: 1) Self-healing function test at room temperature: like Figure 19 As shown, the homogeneous integrated flexible capacitive pressure sensor (hereinafter referred to as "sensor") of Example 4 was cut with a blade, and then the damaged sensor segment was healed through interface contact. After self-repairing for 24 hours at room temperature, the damaged sensor was able to achieve effective connection without breakage.

[0086] To evaluate whether the sensor has similar sensing performance before and after self-repair, the relative capacitance of the undamaged sensor and the damaged and self-repaired sensor was tested as a function of pressure. The results are as follows: Figure 20 As shown, sensitivity is represented by the slope of the tangent line to the curve of relative capacitance versus pressure. The results show that the operating range of the damaged and self-repairing sensor is 0–260 kPa. Within the low-pressure range of 0–30 kPa, the sensor exhibits good sensitivity, reaching 0.130 kPa. -1The ratio between the self-repairing sensitivity and the original sensitivity was used as an evaluation index for the sensor's self-repair efficiency. The measured self-repair efficiency was approximately 100% in the 0–30 kPa range, approximately 93.5% in the 30–100 kPa range, and approximately 80% in the 100–260 kPa range. These results indicate that the sensor in Example 4 has good functional recovery and can meet the application requirements for signal consistency.

[0087] Furthermore, the response and recovery times of the undamaged sensor and the damaged but self-healing sensor were tested under a 5 kPa load, and the results are as follows: Figure 21 As shown in the figure, the original sensor exhibited a response time of 114 ms and a recovery time of 93 ms. The corresponding parameters of the damaged and self-repairing sensor were 112 ms and 95 ms, respectively. It is evident that the response and recovery times of both the undamaged sensor and the damaged and self-repairing sensor exceeded the human tactile perception latency (139 ms). A constant pressure of 10 kPa was applied to both the original and self-repairing sensors, and 1000 load-unload cycles were performed. The results are as follows... Figure 22 As shown, the signals from both sensors exhibit excellent consistency and stability, meeting the application requirements of self-healing sensors.

[0088] 2) Self-healing function test under other environments: To verify whether the sensor could reproduce the sensing signal underwater, the sensor was immersed in water. Figure 23 As shown, the underwater sensor responded when pressure was applied. Even after repair, the damaged sensor was still able to respond to the applied pressure. These results demonstrate that the sensor of Example 4 can recover signals underwater, providing a basis for application in extreme environments such as the ocean.

[0089] 3) Feasibility test of applying homogeneous integrated flexible capacitive pressure sensors to flexible robots: By integrating the sensor from Example 4 into the mechanical gripper of a flexible robot as a force gauge and recording signals when gripping different objects in different working scenarios, the application potential of the sensor in flexible robots can be evaluated.

[0090] Figure 24 The image shows signal changes in a flexible robot equipped with sensors as it grasps a soft toy. Figure 25 This shows the signal changes of a sensor-equipped soft robot during the process of grasping a cactus. From Figure 24 and Figure 25It can be seen that the sensor signals of Example 4 are different when grasping different objects. The comparison of the signals can well reflect the actual grasping behavior of the mechanical gripper, indicating that the sensor of Example 4 has a certain object recognition capability.

[0091] In addition, to simulate potential damage scenarios in real-world applications, a robotic gripper equipped with sensors continuously picks up glass fragments from a pile of broken glass. For example... Figure 26 As shown, the signals during the grasping process differ slightly due to the different shapes of the captured fragments; when sharp glass fragments damage the sensor, the sensing signal is interfered with; when the damaged part of the sensor is in close contact and repaired after 24 hours, the glass fragment is picked up again, and the signal is basically restored. These results indicate that the sensor has the potential for self-healing applications in remote intelligent robots and human-computer interaction.

[0092] Furthermore, to demonstrate the practical application potential of the fabricated sensor as a force gauge for underwater robots, the sensor from Example 4 was attached to the tip of a submarine model to study its underwater sensing performance. Figure 27 As shown, different sensing signals were obtained when the tip of the submarine model was subjected to weak or strong impacts against the container wall. Even after the sensor was damaged by a knife and self-repaired, applying the same impact to the tip of the submarine model still resulted in excellent signal response. These results demonstrate that the sensor possesses underwater sensing capabilities and a self-healing ability for underwater sensing signals, showcasing its application potential in deep-sea scenarios.

[0093] The above results demonstrate that the homogeneous integrated flexible capacitive pressure sensor provided by this invention can meet the practical requirement of signal consistency before and after repair at room temperature. Its self-repair efficiency is close to 100% in the 0–30 kPa range, 93.5% in the 30–100 kPa range, and 80% in the 100–260 kPa range, indicating almost complete recovery of sensing function. This can solve the problem of low signal repair efficiency caused by the mismatch in healing dynamics between different layers of traditional multilayer heterogeneous structure sensors. Furthermore, the homogeneous integrated flexible capacitive pressure sensor provided by this invention can autonomously repair itself and restore sensing function in harsh environments (such as underwater), demonstrating its application potential in specific scenarios such as deep-sea exploration, polar scientific research, and underwater robots.

[0094] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for preparing a self-healing matrix material, characterized in that, Includes the following steps: The amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde and solvent are dispersed to obtain a raw material dispersion. The raw material dispersion is heated to cause the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylformaldehyde to undergo a crosslinking reaction to obtain an intermediate. 1,4-Benzaldehyde and a solvent are mixed to form a 1,4-Benzaldehyde solution. The 1,4-Benzaldehyde solution is then added to the intermediate and stirred until a first gel is formed. The first gel is then dried to obtain the self-healing matrix material.

2. The method for preparing the self-healing matrix material as described in claim 1, characterized in that, The mass ratio of the amino-terminated polydimethylsiloxane, 4,4'-dithiodibenzoylbenzaldehyde, and 1,4-phenylenedialdehyde is 5000:(10~40):(20~35); and / or, The step of dispersing amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde, and a solvent to obtain a raw material dispersion includes: first, mixing the amino-terminated polydimethylsiloxane and the solvent to form a polydimethylsiloxane solution; then, adding 4,4'-dithiodiphenylformaldehyde to the amino-terminated polydimethylsiloxane solution and ultrasonically dispersing it to obtain the raw material dispersion; and / or, The raw material dispersion is heated at 85-95°C for 2-3 hours.

3. A self-healing matrix material, characterized in that, The self-healing matrix material includes the self-healing matrix material prepared by the preparation method described in claim 1 or 2.

4. A method for preparing a self-healing conductive composite material, characterized in that, Includes the following steps: The amino-terminated polydimethylsiloxane, 4,4'-dithiodiphenylformaldehyde and solvent are dispersed to obtain a raw material dispersion. The raw material dispersion is heated to cause the amino-terminated polydimethylsiloxane and 4,4'-dithiodiphenylformaldehyde to undergo a crosslinking reaction to obtain an intermediate. The intermediate and the conductive material are mixed and then ultrasonically dispersed in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material. 1,4-Benzaldehyde and a solvent are mixed to form a 1,4-Benzaldehyde solution. The 1,4-Benzaldehyde solution is added to the dispersion containing the intermediate and conductive material, and the mixture is stirred until a second gel is formed. The second gel is then dried to obtain the self-healing conductive composite material.

5. The method for preparing the self-healing conductive composite material as described in claim 4, characterized in that, The mass ratio of the amino-terminated polydimethylsiloxane, 4,4'-dithiodibenzoylbenzaldehyde, and 1,4-phenylenedialdehyde is 5000:(10~40):(20~35); and / or, The raw material dispersion is heated at 85-95°C for 2-3 hours; and / or, The ultrasonic dispersion treatment in an ice-water bath was carried out for 2 hours; and / or; The conductive material includes a conductive polymer and a carbon-based material, wherein the conductive polymer includes poly(3,4-ethylenedioxythiophene):polystyrene sulfonate, and the carbon-based material includes carbon nanotubes.

6. The method for preparing the self-healing conductive composite material as described in claim 5, characterized in that, The conductive material comprises poly(3,4-ethylenedioxythiophene):polystyrene sulfonate and carbon nanotubes: The mass ratio of the amino-terminated polydimethylsiloxane, carbon nanotubes, and poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is 1:(0.02~0.07):(0.10~0.40); and / or, The step of mixing the intermediate and the conductive material and performing ultrasonic dispersion treatment in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material includes: mixing the intermediate, the conductive material, the nonionic surfactant and the solvent, and performing ultrasonic dispersion treatment in an ice-water bath to obtain a dispersion containing the intermediate and the conductive material.

7. A self-healing conductive composite material, characterized in that, The self-healing conductive composite material includes the self-healing conductive composite material prepared by the preparation method according to any one of claims 4 to 6.

8. A homogeneous integrated flexible capacitive pressure sensor, characterized in that, It includes a dielectric layer and electrode layers disposed on both sides of the dielectric layer, wherein: The electrode layer includes a first self-healing conductive composite material, which is prepared by the preparation method described in claim 6. In the first self-healing conductive composite material, the mass ratio of the carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is (0.05~0.07):0.

25. The dielectric layer includes a second self-healing conductive composite material, which is prepared by the preparation method described in claim 6. In the second self-healing conductive composite material, the mass ratio of the carbon nanotubes to poly(3,4-ethylenedioxythiophene):polystyrene sulfonate is (0.02~0.03):0.

25.

9. A method for fabricating a homogeneous integrated flexible capacitive pressure sensor as described in claim 8, characterized in that, Includes the following steps: A first self-healing conductive composite material and a second self-healing conductive composite material are provided. The first self-healing conductive composite material and the second self-healing conductive composite material are hot-pressed respectively to obtain an electrode layer precursor and a dielectric layer precursor. Microstructures were constructed on the surface of the dielectric layer precursor using 3D printing technology to obtain a dielectric layer precursor with microstructures. The two electrode layer precursors and the two dielectric layer precursors with microstructures are stacked sequentially, wherein the two electrode layer precursors are located on the outermost side, and the two dielectric layer precursors with microstructures are located on the inner side and opposite to each other, forming a stacked structure of "electrode layer / dielectric layer / dielectric layer / electrode layer". The stacked structure is left to stand, allowing the layers to fuse through self-healing, resulting in the homogeneous integrated flexible capacitive pressure sensor.

10. A flexible robot, characterized in that, Includes the homogeneous integrated flexible capacitive pressure sensor as described in claim 8, or includes the homogeneous integrated flexible capacitive pressure sensor prepared by the preparation method described in claim 9.

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