Preparation method of composite molding conductive silica gel

Abstract

The invention discloses a preparation method of composite molding conductive silica gel, and belongs to the technical field of functional polymer composites.The preparation method of the composite molding conductive silica gel comprises a silica gel matrix; the functional network is integrated in the silica gel substrate, the functional network comprises a sensing unit, the sensing unit is configured to generate a detectable resistance signal in response to mechanical deformation, and the resistance signal presents a negative pressure resistance effect in an initial stretching stage. According to the invention, stable and adjustable'negative pressure resistance-positive pressure resistance 'asymmetric response is realized in conductive silica gel, the limitation that a traditional sensor can only provide monotonic signals is changed, a solid hardware foundation is provided for capturing high-dimensional information sensing of strain size, rate and mode, and through an exquisite microstructure design, the sensor can be used for sensing high-dimensional information of strain size, rate and mode. The material not only realizes high sensitivity and high signal-to-noise ratio, but also has unique strain rate sensitivity, so that the material can accurately capture dynamic information which cannot be identified by a traditional sensor.

Description

Technical Field

[0001] This invention belongs to the field of functional polymer composite materials technology, specifically relating to a method for preparing composite molded conductive silicone. Background Technology

[0002] Conductive silicone is a composite material made by dispersing conductive fillers (such as carbon nanotubes, metal particles, etc.) into a flexible silicone matrix. It combines the excellent elasticity of silicone with the electrical properties of conductive fillers, allowing its resistance to change systematically when deformed under external force. This unique force-electric response characteristic makes it an ideal material for manufacturing flexible strain sensors, wearable health monitoring devices, and skin-sensing soft robots, making it one of the key fundamental materials in the field of modern smart hardware.

[0003] However, existing conductive silicone technology faces a prominent core problem: a single response mode and extremely limited information dimensions. Currently, almost all conductive silicone sensors on the market only exhibit the "positive piezoresistive effect," meaning that the resistance value increases monotonically with the increase of tensile strain. This means that regardless of whether a slow heavy pressure or a quick light touch is applied, as long as the resulting deformation is the same, the resistance value output by the sensor will be exactly the same. This makes it impossible for the sensor to distinguish richer dynamic information such as the speed of the action and the pattern of force changes, which greatly limits its application in applications requiring fine interaction and complex scene perception (such as advanced prosthetic control and intensive care).

[0004] However, the "filler random network" model obtained by traditional manufacturing methods is essentially a passive response mechanism. The change in the material's resistance depends entirely on the passive expansion or compression of the filler spacing caused by matrix deformation. This is a macroscopic, continuous, and irreversible process. Therefore, it is necessary to fundamentally get rid of the dependence on random percolation networks and propose a method for preparing composite molded conductive silicone. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of the prior art and provide a composite molded conductive silicone and its preparation method.

[0006] A composite molded conductive silicone includes a silicone matrix and a functional network integrated within the silicone matrix, the functional network including a sensing unit, a stiffness adjustment unit, and a self-healing unit.

[0007] Furthermore, the sensing unit includes multiple pre-formed spiral structure units, each of which consists of a conductive core material and an elastic insulating layer enclosing the conductive core material, and forms an arched microbridge structure inside the silicone matrix in its natural state to achieve the negative piezoresistive effect. When the tensile strain exceeds a preset threshold, it switches to exhibiting a positive piezoresistive effect.

[0008] Through the above technical solution, a novel microstructure is designed to achieve a unique "force-electric" response. This utilizes mechanical deformation to actively construct or disrupt conductive pathways, rather than passively relying on the random breakage of the filler network. Specifically, by encapsulating pre-stretched helical conductive units within a higher-modulus matrix, their springback tendency forms "arched microbridges." When the material is stretched, these microbridges are pulled into direct contact, forming new pathways, thus exhibiting a negative piezoresistive effect in the initial stretching stage. When the strain exceeds a threshold, the microbridges are destroyed, and the resistance changes to positive piezoresistive. This improvement enables the material to possess non-monotonic resistance change characteristics. Its technical effect is to overcome the limitation of traditional sensors that can only provide monotonic signals, providing a hardware foundation for high-dimensional information perception.

[0009] Furthermore, the sensing unit includes multiple shear bands, which are periodically embedded inside the silicone matrix. The shear bands extend at a non-parallel angle to a preset stretching direction, and the concentration of conductive filler inside them is higher than that inside the silicone matrix, so as to achieve the negative piezoresistive effect.

[0010] The above technical solution provides a more flexible design approach to achieve a similar negative piezoresistive effect by utilizing the geometric deformation of the macrostructure under stress to alter the conductive pathway. Specifically, conductive shear strips angled to the stretching direction are manufactured using 3D printing. During stretching, the rotation of the shear strips causes the high-concentration filler inside to re-aggregate, forming temporary pathways. This improvement provides a more flexible and customizable method for achieving the negative piezoresistive effect. The core advantage of this solution lies in its macrostructure and design freedom, lowering the manufacturing threshold. It is particularly suitable for small-batch, multi-variety customized sensor production, such as health monitoring patches for monitoring weak physiological signals like pulse.

[0011] Furthermore, the negative piezoresistive effect is strain rate sensitive, meaning that the resistance decrease during rapid stretching is greater than the resistance decrease during slow stretching; at the same time, the silicone matrix also contains functional fillers, such as carbon nanotubes, graphene, or carbon black, to form a background conductive network to enhance signal stability and baseline conductivity.

[0012] The above technical solution optimizes the dynamic response and fundamental properties of the material. The design concept utilizes the viscoelastic differences between the different components of the material and constructs a redundant conductive network. Structurally, the high-modulus matrix and the highly elastic microbridge structure exhibit a time difference in their strain responses to different rates, endowing the material with the ability to identify strain rates. Meanwhile, the functional filler in the matrix ensures that the material retains a certain degree of conductivity even when the microbridges are not in contact. This improvement allows the material to sense dynamic changes while maintaining static stability, significantly enhancing the sensor's signal-to-noise ratio and reliability, enabling it to operate accurately even in complex environments. Furthermore, the stiffness adjustment unit includes multiple micron-level micro-clamp structure units, which are configured to: separate from each other when uncontrolled, so that the material exhibits a low stiffness state; and mesh with each other when subjected to an external control field, so that the material exhibits a high stiffness state.

[0013] To meet diverse functional requirements, this invention provides a pressure-controlled variable stiffness solution based on the aforementioned technical solutions. This extends the "contact-separation" structural concept to the field of mechanical property control, regulating the macroscopic mechanical properties of materials through changes in microscopic contact states. Specifically, it designs micro-clamps that can engage under a controlled field, enabling reversible switching between soft and hard states of the material. This key improvement utilizes structural design to achieve variable stiffness functionality. The functional objective of this solution shifts from perception to execution, altering the macroscopic modulus of the material through microscopic contact. This addresses the core requirement in soft robotics—the ability to both gently touch and firmly grasp—providing an ideal material that balances rigidity and flexibility. It resolves the core contradiction of traditional soft materials being "too soft to be effective, too rigid to be flexible."

[0014] Furthermore, the self-healing unit includes multiple microcapsules, each containing a brittle outer shell and a liquid conductive repair agent encapsulated inside. When the material breaks, the microcapsule at the break point ruptures, and the released liquid conductive repair agent fills the crack to achieve self-repair of the conductive pathway.

[0015] The above technical solution provides a self-healing approach to improve reliability, expanding the application of multi-material composite concepts and aiming to address material reliability issues. It introduces the concept of an "embedded repair agent" to achieve self-diagnosis and self-repair of damage. Structurally, a liquid repair agent is encapsulated in microcapsules. When a crack occurs, the capsule ruptures, releasing the repair agent to the damaged area. This improvement endows the material with unprecedented self-healing capabilities. This solution focuses on the material's "lifecycle" and "fault tolerance," with an embedded repair mechanism to cope with accidental damage. It solves the survival problem of flexible electronics in extreme environments, significantly improving the long-term reliability and safety of flexible circuits and electronic devices in extreme or inaccessible environments, making it particularly suitable for aerospace and implantable medical devices.

[0016] Furthermore, the present invention provides a method for preparing the above-mentioned composite molded conductive silicone, which includes the following steps: S1. Prefabricating the sensing unit, stiffness adjustment unit and self-healing unit respectively; S2. Mixing each prefabricated body with an uncured silicone matrix prepolymer, and constructing an integrated functional network inside the silicone matrix through multi-material 3D printing or layered casting process; S3. Curing the whole to form the composite molded conductive silicone.

[0017] The above technical solution provides a preparation process that matches the unique structure and differs from conventional methods, precisely constructing the microstructure through a dynamic and continuous process. Specifically, it employs a combination of "co-extrusion-pre-stretching-in-situ curing" to first manufacture helical units with "memory" function, which are then locked inside the matrix. This preparation method features continuous and highly efficient production characteristics, drawing on industrial extrusion and fiber processing technologies. It enables continuous, large-scale production with good product consistency and controllable costs. Addressing the practical problem of the difficulty in scaling up the production of complex microstructures, this improvement is key to the invention's transition from theory to practice, achieving precise and controllable manufacturing of microstructures, ensuring product performance consistency and repeatability, and possessing the potential for industrial production.

[0018] Furthermore, the present invention provides applications of the above-mentioned composite molded conductive silicone, characterized in that it is applied to advanced soft robots, adaptive health monitoring patches, or reconfigurable aerospace electronic devices.

[0019] The aforementioned technical solution clarifies its specific application scenarios, combining the material's unique "force-electric" response, variable stiffness, and self-healing capabilities with actual industrial needs. This key improvement demonstrates the invention's broad applicability and significant market value, providing a revolutionary key material solution for strategic emerging industries such as healthcare, robotics, and electronics, and driving technological progress in related fields.

[0020] The beneficial effects of this invention are as follows: (1) This invention achieves a stable and adjustable “negative piezoresistive-positive piezoresistive” asymmetric response in conductive silicone, which changes the limitation that traditional sensors can only provide monotonic signals. It provides a solid hardware foundation for capturing high-dimensional information perception of strain magnitude, rate and pattern. Through ingenious microstructure design, the material not only achieves high sensitivity and high signal-to-noise ratio, but also has unique strain rate sensitivity, enabling it to accurately capture dynamic information that traditional sensors cannot recognize. (2) Through structural innovation, this invention successfully expands the functional scope to multiple cutting-edge fields such as variable stiffness and self-healing, thereby constructing a smart material platform with rich functions and diverse responses. It provides a variety of preparation methods, from continuous and efficient industrial-grade production to highly flexible customized 3D printing, perfectly balancing the needs of large-scale commercialization and the flexibility of cutting-edge scientific research. This makes the solution proposed in this invention show great application value and broad market prospects in strategic emerging industries such as health care, soft robotics, and flexible electronics. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the conductive silicone layer casting molding process of the present invention; Figure 2 This is a schematic diagram of the conductive silicone 3D printing molding process of the present invention. Detailed Implementation

[0022] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0023] Example 1: Composite Molded Conductive Silicone Based on Spiral Microbridge Structure This embodiment provides a composite molded conductive silicone that integrates sensing, stiffness adjustment and self-healing functions. Its core sensing unit adopts a pre-formed spiral structure unit, and achieves a non-monotonic "force-electric" response through a unique microstructure design.

[0024] 1. Material preparation: Silicone matrix: Dow Corning Sylgard 184 two-component room temperature vulcanizing silicone rubber was selected. The matrix and curing agent were mixed at a mass ratio of 10:1. To construct a background conductive network and improve signal stability, 1% by mass of multi-walled carbon nanotubes (MWCNTs, diameter 10-20 nm, length 5-15 μm) were added to the mixture.

[0025] Percolation theory states that when the concentration of conductive filler in an insulating matrix reaches a critical value (percolation threshold), conductive pathways will form. A 1% MWCNT concentration, slightly below the typical percolation threshold for this system (approximately 1.5%–2%), aims to create a sparse yet effective background network. This network provides baseline conductivity when the material is undeformed, while being itself insensitive to strain, thus highlighting the resistance changes introduced by the helical microbridge structure and improving the signal-to-noise ratio.

[0026] The dispersion process involves first adding MWCNTs to silicone oil and mixing them for 5 minutes at 2000 rpm using a planetary centrifugal mixer (such as THINKYMixer). Then, the mixture is sonicated in an ice bath for 30 minutes using a 300W ultrasonic probe to achieve effective depolymerization and uniform dispersion of the nanotubes. Finally, it is mixed with the RTV matrix and curing agent.

[0027] Sensing unit: Conductive core material: Polyurethane elastic fiber with a diameter of 50μm is selected as the substrate, and liquid metal (gallium indium tin alloy, EGaIn, melting point 10.5℃) is injected through capillary action to form a composite fiber with high conductivity and high ductility.

[0028] Elastic insulation layer: Thermoplastic polyurethane (TPU, such as Estane 5708) solution (10wt% DMF solution) is selected as the insulation layer material. The modulus of TPU (about 20MPa) is significantly higher than that of RTV silicone matrix (about 1.8MPa), and this modulus difference is the key to realizing the "arched microbridge" structure.

[0029] Stiffness adjustment unit: An acrylate-based photosensitive shape memory polymer (SMP) resin containing a photoinitiator (such as Irgacure 2959) is selected. This resin can rapidly crosslink and cure under 365nm ultraviolet irradiation to achieve shape locking. The stiffness adjustment of SMP is based on its glass transition temperature (Tg). Below Tg, the polymer is in a glassy state with high modulus; above Tg, it is in a rubbery state with low modulus. In this embodiment, its temporary shape (interlocking state) is locked by photocuring, so that it maintains high stiffness at room temperature (below Tg); by heating (above Tg), it can be restored to its initial separated state, realizing reversible switching of stiffness.

[0030] The self-healing unit utilizes urea-formaldehyde resin as the microcapsule shell material, encapsulating a liquid epoxy resin repair agent containing silver nanowires (AgNWs, 50nm in diameter and 10μm in length). The average diameter of the microcapsules is controlled at 200±20μm. This self-healing mechanism is based on the principle of "microcapsule rupture – repair agent flow – curing." When the crack extends to the microcapsule, stress concentration causes the brittle shell to rupture, and the released liquid repair agent fills the crack through capillary action. The AgNWs in the repair agent, acting as a highly conductive filler, can rapidly rebuild the conductive pathway at the fracture site after curing, achieving dual repair of both conductive and mechanical properties.

[0031] 2. Preparation steps, refer to Figure 1 : S1. Preform Preparation: Sensing unit preform: EGaIn composite fibers coated with a TPU insulating layer (thickness controlled to 100μm using an dip-coating method) are pre-stretched to 200% of their original length on a stretching table. Subsequently, they are tightly wound in a 0.5mm pitch spiral onto a 1mm diameter PTFE mold and heated in an 80°C oven for 30 minutes to cure and set the TPU layer. After slow cooling, the external force is removed, resulting in a spiral structure unit with strong resilience.

[0032] Stiffness adjustment unit preform: Using high-precision two-photon polymerization (Nanoscribe Photonic Professional GT) 3D printing technology, two micro-clamping structures with dimensions of 500μm x 500μm x 200μm and complementary triangular meshing teeth (tooth height 50μm, tooth tip angle 60°) are printed using SMP resin.

[0033] Self-healing preform: In-situ polymerization was employed. Deionized water containing 1 wt% Span-80 emulsifier was used as the aqueous phase, and AgNWs / epoxy resin repair agent was used as the oil phase. The oil phase was slowly added dropwise to the aqueous phase under stirring at 800 rpm to form an O / W emulsion. Subsequently, urea-formaldehyde prepolymer was added, the pH was adjusted to 2.5 with hydrochloric acid, and the reaction was carried out at 55°C for 3 hours. After washing, drying, and sieving, microcapsules of the target size were obtained.

[0034] S2. Functional Network Construction and System Integration: Mold preparation: Design and 3D print a cuboid mold (50mm x 10mm x 2mm) made of polylactic acid (PLA). The bottom surface of the mold has microgrooves with a depth of 0.3mm, which are used to fix the spiral unit and micro buckle.

[0035] Layered casting and integration: First, pour a 0.5mm thick layer of uncured silicone matrix prepolymer into the mold.

[0036] Subsequently, using precision tweezers, the five prepared spiral structure units were precisely fixed at both ends in the microgrooves of the mold, parallel to the long axis of the mold. Due to the encapsulation effect of the silicone matrix and the resilience of the spiral units themselves, each unit naturally forms an arched microbridge structure with a height of approximately 0.8 mm inside the silicone matrix, with the distance between the tops of adjacent arches being approximately 1 mm.

[0037] Meanwhile, nine pairs (3x3 array) of micro-clamping structural units are embedded into the silicone matrix between the spiral units to ensure that the clamping gap is greater than 100μm and that the units are in an unengaged state.

[0038] Finally, the self-healing microcapsules (approximately 0.1g) are evenly sprinkled onto the silicone matrix where the functional units have been arranged, and the remaining silicone matrix prepolymer is poured until the entire mold is filled.

[0039] S3. Curing process: The entire mold was placed in a vacuum chamber with a vacuum level of -0.08 MPa and evacuated for 15 minutes to remove air bubbles generated during the mixing process.

[0040] Subsequently, it is placed in an 80°C oven for 2 hours to cure, allowing the silicone matrix to fully cross-link and cure, firmly encapsulating all functional units inside, forming an integrated composite conductive silicone.

[0041] 3. Performance Testing: Sensing performance: Connect both ends of the system to the source meter (Keithley 2450) and perform tensile tests using a universal testing machine (Instron 5944).

[0042] Negative piezoresistive effect: When a tensile strain of 0% to 20% is applied to the sample, the resistance value drops from the initial 12.5kΩ to 3.8kΩ, with a change rate as high as -69.6%, exhibiting a significant negative piezoresistive effect. This is because the stretching straightens the arched microbridge structure, and the conductive core tips of adjacent spiral units come into contact with each other, forming a low-resistance parallel path.

[0043] Positive piezoresistive effect: When the strain exceeds a preset threshold of 20%, the microbridge structure is overstretched, and the contact points begin to slip or separate. At the same time, the spiral unit itself is elongated, leading to an increase in resistance, and the resistance value begins to rise. At 50% strain, the resistance rises back to 15.2kΩ.

[0044] Strain rate sensitivity: At 10% strain, the resistance decrease during rapid stretching (100% / s) (-45%) is 50% greater than that during slow stretching (1% / s) (-30%). This is attributed to the difference in viscoelastic response between the high-modulus TPU insulation layer and the low-modulus silicone matrix. During rapid deformation, the matrix does not have enough time to fully relax, resulting in more adequate microbridge contact.

[0045] Cyclic stability: After 1000 cycles of testing at 0% to 15% strain, the resistance response curve remains highly consistent with a drift of less than 5%, demonstrating excellent durability.

[0046] Stiffness adjustment: Tested using a dynamic thermomechanical analyzer (DMA). At room temperature, in an uncontrolled state, the Young's modulus of the material is approximately 0.52 MPa (low stiffness state). Irradiating the material with 365 nm ultraviolet light at a power of 10 mW / cm² for 60 seconds caused the SMP micro-clamps to engage. At this point, the Young's modulus of the material increased to 5.8 MPa, achieving a stiffness reversible switching of more than 11 times. Heating the material to 80°C (approximately 60°C above the Tg of the SMP) and holding for 5 minutes allowed the micro-clamps to re-engage, and the stiffness was restored.

[0047] Self-healing properties: A 0.5 mm wide through-cut was made in the middle of the sample using a blade, causing the resistance to jump to infinity (20 MΩ). Due to the rupture of microcapsules at the cut, the liquid conductive repair agent automatically filled the crack. After standing at room temperature for 30 minutes, the repair agent initially cured, and the material's resistance recovered to 88% of its initial value (approximately 11 kΩ). After 24 hours, the repair agent was fully cured, and the resistance stabilized at 10.5 kΩ, achieving a recovery rate of 84%. Simultaneously, tensile testing showed that the fracture strength at the repaired area recovered to over 70% of the original material.

[0048] Example 2: Composite Molded Conductive Silicone Based on Shear Band Structure The main difference between this embodiment and Embodiment 1 lies in the structure of the sensing unit. It adopts periodically embedded shearing strips and is manufactured in one piece using multi-material 3D printing technology, demonstrating greater design freedom and customization potential.

[0049] 1. Material preparation: Silicone matrix: The same RTV silicone with 1% MWCNT added was used as in Example 1.

[0050] Sensing unit (shear tape): Conductive silicone is selected as the printing material. Its formula is a mixture of RTV silicone and carbon black (CB, particle size about 40nm) with a mass fraction of 15%. The Young's modulus of this conductive silicone is about 3.5MPa, which is higher than that of the matrix silicone.

[0051] Stiffness adjustment unit and self-healing unit: Same as in Example 1.

[0052] 2. Preparation steps, refer to Figure 2 : S1. Preform preparation: Only the micro-clamps of the stiffness adjustment unit and the microcapsules of the self-healing unit need to be prepared, using the same method as in Example 1.

[0053] S2. Functional Network Construction and System Integration: A multi-material inkjet 3D printer (such as the Stratasys J750) is used. A 3D model is designed on a computer, and the model includes: Main body: Composed of base silicone material.

[0054] Sensing component: 10 shear strips, each 0.5 mm wide and 0.5 mm thick, extending at a 45° angle to the sample's pre-set stretching direction, are periodically arranged inside the main body at 2 mm intervals.

[0055] Adjustment and repair section: preset positions of micro-clamps and microcapsules.

[0056] Start the printer and print layer by layer according to the model, with a layer thickness of 16μm. The print head ejects matrix silicone prepolymer or conductive silicone prepolymer at designated locations based on the model information, and precisely places micro-clamps and microcapsules in predetermined positions during the printing process.

[0057] S3. Curing treatment: After printing, place the entire green body in an 80°C oven for 2 hours to cure, and obtain the final product.

[0058] 3. Performance Testing: When the sample is stretched along a preset direction, the internal 45° shear band rotates and undergoes geometric deformation. Within the tensile strain range of 0% to 30%, the resistance value decreases from 8.2kΩ to 2.5kΩ, with a change rate of -69.5%, exhibiting a significant negative piezoresistive effect.

[0059] Tension-induced shear bands undergo "pure shear" deformation, causing the originally randomly distributed high-concentration carbon black particles inside to rearrange and aggregate along the principal stress direction under the action of local stress field, forming a large number of temporary conductive paths, which leads to a sharp drop in resistance.

[0060] This flexible design allows for linear adjustment of the sensor's sensitivity (GF value) and effective operating range by modifying the angle (e.g., 30°, 60°), width, and spacing of the shear bands. For example, the 45° angle design provides optimal sensitivity and linearity within the 0%–30% strain range.

[0061] The stiffness adjustment and self-healing functions in this embodiment are similar to those in Embodiment 1, and will not be described again.

[0062] Application example extension: Healthcare: Adaptive Pulse Monitoring Patch An ultrathin (<1 mm thick), stretchable pulse monitoring patch was prepared using the shear band structure of Example 2. Its 45° shear band structure is extremely sensitive to weak, periodic skin deformation (caused by pulse waves).

[0063] When in use, the patch is applied to the radial artery in the wrist. With each heartbeat, the arterial pulsation causes a tiny strain of about 0.1% in the skin, and the shear band within the patch undergoes a slight deformation, resulting in a detectable negative piezoresistive wave signal that is synchronized with the pulse wave.

[0064] Compared to traditional piezoresistive sensors, its negative piezoresistive effect exhibits higher sensitivity (GF>10) under minute strains, enabling it to capture fine characteristics of pulse waves (such as tidal waves and dicrotic waves), providing richer data for cardiovascular disease diagnosis. The patch's low-modulus design ensures wearing comfort and the feasibility of long-term monitoring. Its self-healing function guarantees continued operation even after accidental scratches during daily activities.

[0065] Electronic equipment field: Reconfigurable aerospace electronic equipment The spiral microbridge structure of Example 1 is used and designed as part of a satellite antenna or flexible circuit board.

[0066] During satellite launch, when subjected to severe vibrations and overloads, ultraviolet light can be used to activate the micro-clamps, temporarily "rigidifying" the flexible circuit board and improving its structural stability to prevent damage. Once in space, heating is used to separate the micro-clamps, restoring the circuit board's flexibility. It can then be unfolded or reshaped as needed to adapt to different communication requirements.

[0067] Its unique "negative-positive" piezoresistive response characteristic serves as a "damage threshold" indicator. Within the 0%–20% strain range (normal operating range), the resistance decreases; if the strain exceeds 20% due to unexpected events such as micrometeoroid impacts, the resistance will rise sharply, and the system can immediately detect the anomaly and trigger an alarm or reconfigure the circuit. The self-healing unit can automatically repair the conductive path after minor puncture damage, ensuring the long-term reliability of the equipment in extreme environments, which is crucial for spacecraft that are inaccessible or have extremely high maintenance costs.

[0068] In the field of flexible robotics: soft robot manipulators Using the helical microbridge structure of Example 1, a soft robotic manipulator integrating sensing, execution, and self-healing functions was fabricated. In use, the manipulator is mounted on the end effector of a robotic arm to perform complex grasping tasks.

[0069] First, when grasping a fragile item (such as an egg), the system controls the micro-clamp structure to be in a disengaged state. At this time, the manipulator exhibits low stiffness (Young's modulus ~0.5MPa), like a soft tentacle. When the finger touches the object's surface, the internal spiral microbridge sensing unit undergoes a slight deformation due to the force, resulting in a significant negative piezoresistive effect. This highly sensitive resistance signal is acquired in real time, enabling the robot to accurately sense contact pressure, object contours, and sliding tendencies, thereby achieving a gentle, adaptive wrapping motion and avoiding damage to the object.

[0070] Subsequently, once the wrapping is complete, the system illuminates the manipulator with a built-in ultraviolet light source, causing the micro-clamping structure made of photosensitive SMP material to engage rapidly. The macroscopic stiffness of the manipulator instantly increases by more than an order of magnitude (Young's modulus ~5.8MPa), transforming it from a soft "fingers" into a robust "clamp." This "combination of rigidity and flexibility" allows it to firmly grasp and move objects, preventing slippage even under acceleration or vibration, demonstrating load capacity and stability far exceeding that of purely soft actuators.

[0071] During operation, if the operator is accidentally cut by a sharp object, damaging the internal conductive pathway, the sensor will immediately detect an abnormal surge in resistance. Simultaneously, the microcapsule at the damaged area will rupture, releasing a liquid conductive repair agent that automatically fills the crack. After standing at room temperature for approximately 30 minutes, the conductive pathway is rebuilt, and the sensor function recovers to over 85% of its initial performance. This self-healing capability gives the operator strong fault tolerance and survivability, significantly reducing maintenance costs and ensuring long-term reliable operation in unstructured and unpredictable environments.

[0072] Compared to traditional soft or rigid grippers, the manipulator of this invention represents a revolutionary breakthrough. It not only possesses the safety and adaptability of a soft robot but also the power and precision of a rigid actuator. This multifunctionality, integrating variable stiffness, high-sensitivity sensing, and self-healing, provides an ideal hardware foundation for the next generation of intelligent soft robots, enabling them to perform a wider range of complex tasks, from delicate manipulation of biological tissues to robust industrial assembly.

[0073] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention.

Claims

1. A composite molded conductive silicone, characterized in that, include: Silicone matrix; A functional network, integrated within the silicone matrix, comprising: The sensing unit is configured to generate a detectable resistance signal in response to mechanical deformation, and the resistance signal exhibits a negative piezoresistive effect during the initial stretching phase. A stiffness adjustment unit is configured to change the overall stiffness of the silicone system in response to an external control field; and The self-healing unit is configured to automatically repair the conductive path when the material breaks.

2. The composite molded conductive silicone according to claim 1, characterized in that, The sensing unit includes multiple pre-formed spiral structure units. Each spiral structure unit consists of a conductive core material and an elastic insulating layer that wraps the conductive core material. In its natural state, it forms an arched microbridge structure inside the silicone matrix to achieve the negative piezoresistive effect. When the tensile strain exceeds a preset threshold, it switches to exhibiting a positive piezoresistive effect.

3. The composite molded conductive silicone according to claim 1, characterized in that, The sensing unit includes multiple shear bands, which are periodically embedded inside the silicone matrix. The extension direction of the shear bands is at a non-parallel angle to the preset stretching direction, and the concentration of conductive filler inside the shear bands is higher than the concentration of conductive filler inside the silicone matrix, so as to achieve the negative piezoresistive effect.

4. The composite molded conductive silicone according to claim 2 or 3, characterized in that, The negative piezoresistive effect is strain rate sensitive, meaning that the resistance decreases more rapidly during stretching than during slow stretching.

5. The composite molded conductive silicone according to claim 1, characterized in that, The stiffness adjustment unit includes multiple micron-level micro-clamp structure units, which are configured to: separate from each other when uncontrolled, so that the material exhibits a low stiffness state; and mesh with each other when subjected to an external control field, so that the material exhibits a high stiffness state.

6. The composite molded conductive silicone according to claim 5, characterized in that, The external control field is an electric field, a magnetic field, or a temperature field.

7. The composite molded conductive silicone according to claim 1, characterized in that, The self-healing unit includes multiple microcapsules, each containing a brittle outer shell and a liquid conductive repair agent encapsulated inside. When the material breaks, the microcapsule at the break point ruptures, and the released liquid conductive repair agent fills the crack to achieve self-repair of the conductive pathway.

8. A method for preparing composite molded conductive silicone as described in any one of claims 1 to 7, characterized in that, Includes the following steps: S1. Prepare preforms of the sensing unit, stiffness adjustment unit and self-healing unit respectively; S2. Mix each preform with an uncured silicone matrix prepolymer, and construct an integrated functional network inside the silicone matrix through multi-material 3D printing or layered casting process; S3. The entire assembly is cured to form the composite conductive silicone.

9. The method for preparing composite molded conductive silicone according to claim 8, characterized in that, In step S1, when preparing the sensing unit preform, an uncured elastic insulating layer prepolymer is wrapped around the conductive core material through a co-extrusion process, and then pre-stretched, spiral-shaped and pre-cured to obtain a pre-formed spiral structure unit.

10. An application of the composite molded conductive silicone as described in any one of claims 1 to 7, characterized in that, Applications include advanced soft robots, adaptive health monitoring patches, and reconfigurable aerospace electronic devices.

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