Intelligent composite fabric with pressure sensing and thermal response functions, preparation and application

Abstract

The invention discloses an intelligent composite fabric with pressure sensing and thermal response functions, preparation and application, and belongs to the technical field of intelligent textiles. The composite fabric is formed by weaving conductive core-sheath yarns through a plain weave interweaving process, warp groups I and weft groups I form a distributed sensing array, the used conductive core-sheath yarns maintain a contact / separation initial state by taking basic yarns as sheath layers, a conductive tencel core layer and a dielectric layer are integrated into a single-yarn structure, and the conductive tencel core layer and the dielectric layer are integrated into a single-yarn structure. High-sensitivity, high-linearity and signal-drift-resistant wide-area pressure monitoring is realized through the deformation of the dielectric layer triggered by the pressure. The conductive core sheath yarn is embedded in the weft yarn group II to form a uniform conductive network, and accurate temperature control is achieved based on the Joule heating effect. The sensing and heating unit is constructed by using a textile process, the porosity and mechanical flexibility of natural fibers are retained, and the sensing and heating unit has the characteristics of air permeability, moisture permeability, light weight, softness and bending resistance.

Description

Technical Field

[0001] The present invention belongs to the technical field of smart textiles, and specifically relates to smart composite fabrics with both pressure sensing and thermal response functions, and discloses a preparation method and related applications thereof. Background Art

[0002] As socioeconomic levels rise, people's awareness of health management is growing, and medical devices are increasingly becoming more intelligent, portable, and high-precision. In line with this trend, wearable biosensors, with their ability to monitor vital signs (such as pulse, respiration, and movement) in real time, have become an ideal solution for disease prevention, clinical monitoring, and health management. However, current mainstream wearable materials often use polymer film substrates, which can easily cause adverse reactions such as skin redness, swelling, and stinging after long-term contact, hindering user compliance and device sustainability. To balance functionality and wearable comfort, researchers have proposed combining conductive functional units with traditional fibers to develop new sensors based on smart textiles. By upgrading traditional textiles, which possess natural flexibility, elasticity, and skin-friendliness, into smart wearable devices, they leverage the advantages of their underlying materials to meet diverse health monitoring needs. Compared to traditional biosensors, wearable biosensors based on smart fibers and textiles not only enable on-site, real-time monitoring but also offer significant advantages in disease prevention, clinical diagnosis and treatment optimization, and health management. They also provide innovative solutions for reducing healthcare costs, alleviating the burden on the healthcare system, and improving patients' quality of life. For example, WANG Y, et al. Structural architecture of wearable materials based on tri-component elastic-conductive composite yarn: toward a Joule heating application [J]. Textile Research Journal, 2019, 89 (16): 3303- 3311. designed a three-component elastic-conductive composite yarn (t-ECCYs) with an "elastic core layer-conductive middle layer-flexible protective outer layer" structure. It is integrated through spiral wrapping or coaxial spinning process and exhibits fast and uniform Joule thermal response under voltage or strain, which is suitable for local thermal therapy scenarios. Nan et al. A stretchable, highly sensitive, and multimodal mechanical fabric sensor based on electrospun conductive nanofiberyarn for wearable electronics [J]. Advanced Materials Technologies, 2019, 4 (3): 1800338. developed a fabric sensor with high flexibility and weavability that can detect mechanical forces caused by pressure, strain and bending.The fabric-like sensor is made of a composite yarn (GCNF@ECYs) of graphene oxide-doped polyacrylonitrile nanofibers and in-situ polymerized conductive polypyrrole wrapped around elastic yarn. The GCNF@ECY sensor unit exhibits high sensitivity, a wide pressure sensing range, and excellent cyclic stability and repeatability, enabling it to capture multidimensional mechanical signals such as respiration, pulse, and human motion.

[0003] Although the above technologies have achieved thermal response or pressure sensing functions respectively, their limitations are still significant: 1) Single function: Existing sensors only monitor a single physical quantity (such as temperature or pressure) and cannot achieve multimodal data fusion (such as simultaneous monitoring of temperature and strain), making it difficult to fully reflect complex physiological states; 2) System isolation: The monitoring module and physical therapy module (such as heating, electrical stimulation) use independent power supply and control units, and cannot dynamically adjust treatment parameters based on real-time physiological data to form a "perception-feedback" closed loop.

[0004] To address the above problems, there is an urgent need to develop an intelligent composite fabric that integrates pressure sensing and thermal response functions to break through the limitations of monitoring a single physical quantity and realize integrated closed-loop control of monitoring and treatment. Summary of the Invention

[0005] In response to the above-mentioned problems, the present invention aims to propose an intelligent composite fabric with both pressure sensing and thermal response functions. Through innovations in material design and system integration, mechanical force perception and adjustable thermal response functions are simultaneously realized in a single textile, providing technical support for the next generation of wearable medical and sports equipment. It solves the technical bottlenecks of traditional sensor structures that are complex and uncomfortable to wear. It can be applied to medical monitoring, sports protection and other fields to achieve dynamic coordination of pressure distribution monitoring and thermal therapy functions.

[0006] In order to achieve the above object, the technical solution adopted by the present invention is as follows: A method for preparing an intelligent composite fabric comprises the following steps: 1) Repeating the process of coating the Tencel yarn with a conductive material layer and drying until the resistance value per unit length of the yarn tends to be stable, thereby obtaining a conductive Tencel yarn; 2) Using a braiding machine, the conductive Tencel yarn is cross-woven to form a core layer structure, and the base yarn is cross-woven to form an outer sheath structure covering the core layer, thereby obtaining a conductive core-sheath yarn; 3) Construct a double-warp and double-weft plain weave system, in which: warp yarn group I and weft yarn group I are both composed of conductive core-sheath yarn; warp yarn group II uses ordinary yarn, and weft yarn group II is composed of conductive core-sheath yarn and ordinary yarn arranged alternately in a set ratio; the two groups of warp and weft yarns are fed synchronously into the loom according to a predetermined ratio, and the smart composite fabric is formed by plain weave interweaving.

[0007] Furthermore, in step 1), the thickness of the Tencel yarn is 30-60 D, the conductive material is conductive silver paste, and the coating process is completed by passing the Tencel yarn through an oiler filled with 50-65 wt% conductive silver paste, the drying temperature is 50-80°C, and the drying time is 30-60 min.

[0008] Furthermore, in step 2), the thickness of the conductive Tencel yarn of the braided core layer structure is 40-60D and the number of roots is 8 to 16, the thickness of the base yarn of the braided outer sheath structure is 60-80D and the number of roots is 8 to 16, and the number of roots of the base yarn used is not less than the number of roots of the conductive Tencel yarn; the base yarn is one of high-elastic nylon yarn, polyester yarn, cotton yarn, wool yarn, viscose yarn, and acrylic yarn, or a combination of two.

[0009] Furthermore, in step 2), the weaving speed is 5-30 rpm, and the winding speed is 0.5-5 m / min.

[0010] Furthermore, in step 3), the warp yarn group I and the weft yarn group I together constitute the warp and weft yarn group I, and the warp yarn group II and the weft yarn group II together constitute the warp and weft yarn group II. The warp and weft yarn group I and the warp and weft yarn group II are fed synchronously into the loom at a ratio of 1:5~20.

[0011] Furthermore, in step 3), the common yarn is one of high-elastic nylon yarn, polyester yarn, cotton yarn, wool yarn, viscose yarn, and acrylic yarn; and the weft yarn group II is composed of conductive core-sheath yarn and common yarn arranged alternately in a ratio of 1:3 to 20.

[0012] Furthermore, in step 3), the warp yarn group I and the weft yarn group I are arranged in an equidistant pattern, wherein the lateral and longitudinal spacings of adjacent conductive core sheath yarns are controlled at 1 to 10 cm, and the number of warp yarns and the number of weft yarns are configured in equal amounts of 2 to 100, thereby constructing an array-type sensing matrix of 2*2 to 100*100.

[0013] Furthermore, in step 3), the spacing between adjacent conductive core-sheath yarns in weft yarn group II is controlled to be 1-10 cm.

[0014] The present application also claims protection for an intelligent composite fabric having both pressure sensing and thermal response functions prepared using the above method. The warp yarn group I and the weft yarn group I are orthogonally woven to form a distributed sensing array, and each interweaving point in the array constitutes a discrete pressure sensing unit to realize spatial dynamic monitoring of contact pressure; the conductive core sheath yarn embedded in the weft yarn group II forms an independent temperature control module based on the Joule heating effect after being energized.

[0015] The above-mentioned intelligent composite fabric with both pressure sensing and thermal response functions can be used in medical monitoring, sports monitoring and other fields.

[0016] The beneficial effects of the present invention are: 1. The smart composite fabric disclosed in this application is woven from specially prepared conductive core-sheath yarns. Two sets of differentially configured warp and weft yarns are alternately fed into a loom, allowing fabrics of varying sizes and specifications to be produced on demand. Its array capacitive sensing function is achieved through the warp-and-weft interwoven conductive core-sheath yarn structure. When pressure acts on the sensing unit, the dielectric layer composed of the base yarns on the outer layer of the conductive core-sheath yarn deforms, causing significant changes in the electrical signal, thereby enhancing sensing sensitivity. The conductive core-sheath yarn integrates the conductive electrode and dielectric layer into a single structure, simplifying the complex architecture of traditional sensors. The conductive core-sheath yarn embedded in weft yarn group II also generates Joule heating when energized, forming an independent temperature control module. The evenly distributed conductive network also ensures excellent uniformity in electrical-to-thermal conversion within the fabric. 2. This application uses warp yarn group I and weft yarn group I to jointly construct an orthogonal braiding system of conductive core-sheath yarns to form a distributed sensing array structure. Each interweaving point in the array constitutes a discrete pressure sensing unit. The sheath layer of the conductive core-sheath yarn is the base yarn, and the core layer is the conductive Tencel yarn. The presence of the sheath layer ensures that the sensing unit maintains a stable contact / separation initial state under no pressure. This design not only ensures high-resolution and high-reliability pressure detection, but also avoids the signal drift problem of traditional sensors. The sensing unit exhibits high linear response characteristics and continuous gradient signal output stability over a wide pressure range, while also having fast response speed, excellent mechanical durability, and long-term sensing stability. 3. This application addresses the technical bottleneck of existing array sensors being limited to a single spatial pressure monitoring function. It innovatively proposes a fabric structure design based on conductive core-sheath yarns. Through a three-dimensional orthogonal weaving process, the intelligent composite fabric simultaneously achieves the dual functions of spatial pressure distribution monitoring and adaptive thermal therapy. Furthermore, the unique sheath encapsulation structure of the conductive core-sheath yarns enables the composite fabric to meet the stringent electromechanical stability requirements of washable smart textiles. 4. This application addresses the technical shortcomings of traditional polymer film pressure sensor arrays, such as poor air permeability and insufficient flexibility (which can easily lead to sweat accumulation and skin irritation when worn for a long time). By innovatively using conductive core-sheath yarn as the core material, this material retains the porosity and mechanical compliance of natural fibers, ensuring flexibility and structural scalability. Combined with a three-dimensional textile process, this dual-functional composite fabric fully inherits the inherent properties of textile substrates, such as air permeability and moisture permeability, light weight, softness, and resistance to repeated bending. This not only achieves the integration of pressure sensing and thermal therapy functions, but also fundamentally solves the problem of wearable comfort. 5. To address the high cost of traditional pressure sensors due to their reliance on complex processes such as etching and printing, this application innovatively uses a weaving process to directly construct conductive core-sheath yarns and further weaves a dual-functional composite fabric, which has the significant advantages of a simple process flow, low production cost, and high production efficiency. 6. The dual-function composite fabric developed in this application demonstrates multi-scenario applicability in the field of smart wearables. Its excellent fabric fit can accurately monitor the activities of various parts of the human body, and can identify both small movements and large-strain motion states. The fabric is particularly suitable for monitoring the body pressure distribution of bedridden patients. It can not only prevent the formation of pressure sores, but also simultaneously provide local adaptive thermal therapy functions, thereby achieving dynamic coordination between health monitoring and physical therapy intervention. At the same time, the material can be seamlessly integrated into the inner layer of sports protective gear, and the flexible sensor array composed of interwoven points can capture three-dimensional mechanical loads in real time, and intelligently adjust the heating power of the conductive core sheath yarn based on the ambient temperature, so that the body surface microenvironment temperature is always maintained in the physiological comfort range, providing an integrated solution for sports protection and thermal management. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 Flowchart for preparing the smart composite fabric in Example 1, wherein Ⅰ-braiding, Ⅱ-weaving; 1-conductive Tencel yarn, 2-high-elastic nylon yarn, 3-conductive core-sheath yarn, 4-smart composite fabric; Figure 2 This is a test diagram of the relative change in capacitance of the 12-conductive core-sheath yarn sensor unit under 0-100 kPa; Figure 3 This is a test diagram of the relative change in capacitance of the 12-conductive core-sheath yarn sensing unit at different compression rates; Figure 4 This is a test diagram of the capacitance response time of the 12-conductive core-sheath yarn sensor unit under 100 kPa; Figure 5 This is a graph showing the cyclic compression stability test of a 12-conductive core-sheath yarn sensing unit at 50 kPa; Figure 6 The electrothermal performance diagram of 12-conductive core-sheath yarn under different voltages; Figure 7 This is a graph showing the long-term electrothermal stability test of 12-conductive core-sheath yarn at a voltage of 1.2 V; Figure 8 This is a test diagram of the relative change in capacitance of the 12-conductive core-sheath yarn sensor unit at different temperatures; Figure 9 This is a test diagram of the relative change in capacitance of the 12-conductive core-sheath yarn sensor unit before and after several washes; Figure 10 The electrothermal conversion performance test diagram of 12-conductive core-sheath yarn before and after washing; Figure 11 Schematic diagram of the structure of the smart composite fabric; Figure 12 Pressure distribution maps and infrared heat maps for objects of different shapes placed on the smart composite fabric; DETAILED DESCRIPTION

[0018] In order to enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention is further described below in conjunction with the accompanying drawings and embodiments. Example 1

[0019] This embodiment discloses a method for preparing a smart composite fabric. The preparation process is as follows: Figure 1 , the specific preparation steps are as follows: 1) Preparation of conductive Tencel yarn: 30 D Tencel yarn was passed through an oiler filled with 55 wt% conductive silver paste to ensure uniform adhesion of the silver paste to the fiber surface. The coated yarn was wound onto a winding machine and rolled into a bobbin. The bobbin was dried in a 60°C oven for 30 min. The silver paste coating and drying process was repeated until the resistance per unit length of the yarn stabilized. 2) Preparation of conductive core-sheath yarn: 40D conductive Tencel yarn (core layer) and 60D high-elastic nylon yarn (sheath layer) were wound onto braided bobbins using a bobbin winding machine. Subsequently, 12 core-layer and 12 sheath-layer yarns were sequentially loaded into the braiding machine. The clutch was engaged to start the device. The braiding speed was synchronously controlled to 6 rpm and the winding speed to 1 m / min, while maintaining tension balance between the yarns. The conductive Tencel yarns were cross-woven to form a conductive core layer structure, and the outer layer was cross-wrapped with high-elastic nylon yarns to form the sheath layer. Finally, a composite conductive core-sheath yarn (core conductive layer / sheath insulating structure) was produced, which was recorded as 12-conductive core-sheath yarn.

[0020] 3) Preparation of Smart Composite Fabrics: Using a plain weave structure, two warp and weft yarn systems were designed. The first system consisted of conductive core-sheath yarns (10 warp yarns and 10 weft yarns, each with a 1cm spacing between adjacent warps and wefts). The second system consisted of a blend of high-elastic nylon yarns and conductive core-sheath yarns (the warp yarns were high-elastic nylon yarns, and the weft yarns were fed alternately in a 1:5 ratio of conductive core-sheath yarn to high-elastic nylon yarn, with 2cm spacing between the core-sheath yarns). The two warp and weft yarns were fed synchronously into the loom at a 1:5 ratio and interwoven into a plain weave to form a composite fabric. The first conductive core-sheath yarn served as a sensor array, providing large-area stress sensing capabilities, while the second hybrid yarn balanced mechanical properties with electrothermal requirements.

[0021] Related performance tests 1. Pressure sensing performance test: A sensing unit in the smart composite fabric (each warp and weft interweaving point of the first warp and weft system is used as a sensing unit) is connected to an LRC bridge (TH2830, Changzhou Tonghui Electronics Co., Ltd.) and fixed in the fixture of a flexible electronic multimodal testing system (ST600C, Suzhou Shengte Intelligent Technology Co., Ltd.). The test is initiated after adjusting the system parameters. The sensing unit is compressed at a constant speed of 100 mm / min using the ST600C, and the TH2830 is used to collect the dynamic response data of the capacitance under different pressures during the compression process in real time, realizing electrical-mechanical collaborative characterization.

[0022] The results are as follows Figure 2 As shown in the figure, the sensing unit exhibits capacitive response characteristics in the pressure range of 0-100 kPa, and its relative change rate shows a positive growth trend with increasing pressure, with the maximum relative change rate reaching 228%, verifying the unit's high linear response capability and continuous gradient signal output stability under a wide range of pressures.

[0023] Compression rate correlation test: Under a constant pressure of 50 kPa, the flexible electronic testing system compresses the sensing unit at gradient rates (50, 100, 150, 200 mm / min) and simultaneously collects LCR bridge capacitance data ( Figure 3 The results show that the deviation of the relative rate of change of capacitance at different compression rates is small, indicating that the electric-mechanical response of the sensor unit is not closely related to the external loading rate. This verifies its anti-interference ability in a wide speed range and meets the requirements of stable monitoring in dynamic scenes.

[0024] Response speed test: Under a pressure of 100 kPa, the capacitance response characteristics of the sensor unit were tested through compression-recovery cycles. The response time of the stretching process was measured to be 71 ms, and the response time of the recovery process was 70 ms. The fast sensor response speed is conducive to real-time feedback of the sensor signal ( Figure 4 ).

[0025] Mechanical durability test: Under 50 kPa cyclic compression load, the sensor unit maintains a stable capacitance signal after 12,000 cycles ( Figure 5 ), indicating a highly consistent response to cyclic stress, confirming the device’s excellent mechanical durability and long-term sensing stability, making it suitable for practical applications requiring repeated mechanical loading.

[0026] 2. Thermal response capability test: A 10 cm long 12-conductive core sheath yarn was connected to a regulated DC power supply (ambient temperature was around 25°C). A gradient voltage (0.8, 1.2, 1.6, and 2.0 V) was applied and its temperature rise characteristics were monitored in real time using a multi-channel thermocouple (10-second intervals). The results showed that the electrothermal temperature of the 12-conductive core sheath yarn increased steadily with increasing voltage. The electrothermal temperature of the 12-conductive core sheath yarn was 39.5°C at a voltage of 0.8 V, 52.8°C at a voltage of 1.2 V, 65.6°C at a voltage of 1.6 V, and 78.1°C at a voltage of 2 V. This confirms that the material can achieve precise temperature control through voltage regulation and is suitable for application scenarios requiring gradient temperature output ( Figure 6 ).

[0027] Thermal response stability test: A voltage of 1.2 V was applied to the 12-conductive core-sheath yarn for 30 minutes, and its temperature was found to remain stable through real-time monitoring ( Figure 7 This stability stems from its unique weaving process: the conductive core-sheath yarn's optimized structure effectively suppresses thermal decay even under prolonged voltage loads. Experimental results demonstrate that this material achieves stable temperature output at varying voltages, meeting the demands for precise temperature control and long-lasting performance in everyday electric heating scenarios.

[0028] 3. Verify the impact of thermal response on its sensing performance: The sensing unit in the smart composite fabric (i.e., the warp and weft interweaving point of the first set of warp and weft yarn systems) is connected to an LRC bridge (TH2830, manufactured by Changzhou Tonghui Electronics Co., Ltd.). The sensing unit is then laid flat on the surface of the conductive core-sheath yarn fabric (referring to the conductive core-sheath yarn portion embedded in the weft yarn of the second set of warp and weft yarn systems) to form physical contact. The purpose is to synchronously monitor the capacitance change of the sensing unit under heating conditions (by energizing the conductive core-sheath yarn to generate heat) to verify whether temperature changes interfere with the pressure sensing performance.

[0029] After connecting the conductive core-sheath yarn fabric to a DC regulated power supply, the entire test system was secured in the fixture of a flexible electronics multimodal test system (ST600C, Suzhou Shengte Intelligent Technology Co., Ltd.), ensuring that both ends of the sensor unit were securely clamped. After adjusting the system parameters, the test was initiated.

[0030] Under the temperature conditions of 25℃, 50℃, 60℃ and 70℃ (using a constant temperature heating stage for temperature control), a pressure of 50kPa is applied to the sensing unit and its relative capacitance change rate is measured. Figure 8 As shown, the relative capacitance change of the sensing unit remains stable in different temperature environments, indicating that the material's capacitance characteristics are significantly insensitive to temperature. When the composite fabric simultaneously performs electrothermal conversion and pressure monitoring functions, the pressure monitoring accuracy is not affected by the thermal response process.

[0031] 4. Material durability test: The durability of the material was verified through a standard washing experiment: the smart composite fabric was placed in a commercial washing machine and after a standard machine wash (25°C), a 50 kPa pressure was applied to the sensing unit and its relative capacitance change rate was measured. The conductive core-sheath yarn was connected to a regulated DC power supply (ambient temperature was around 25°C) and a 2.0 V voltage was applied. Its temperature rise characteristics were monitored in real time using a multi-channel thermocouple. The pressure sensing accuracy and electrothermal conversion efficiency of the material before and after washing were compared and analyzed. The test data showed that after multiple machine washes, the composite fabric still maintained a stable relative capacitance change rate ( Figure 9 ) and electrothermal response temperature ( Figure 10 This stability stems from the unique sheath-encapsulation structure of the conductive core-sheath yarn, which effectively isolates water molecules from penetrating, allowing the electrode network to maintain a complete conductive pathway even during washing. This property enables the composite fabric to meet the stringent electromechanical stability requirements of washable smart textiles.

[0032] 5. Each interweaving point of the first set of warp and weft yarns is used as a sensing unit. The first set of warp and weft yarns are connected to the data acquisition system, and a distributed sensing unit array is constructed using the interweaving points. When external force is applied, the changes in the electrical signals of the relevant sensing units can be intuitively monitored, thereby accurately identifying the spatial distribution of pressure. When the number of warp and weft yarns in the first set is 10, the interweaving forms a 10*10 sensing array. ( Figure 11 The black solid line network) can accurately reconstruct the pressure distribution profile by monitoring the capacitance changes of 100 sensing units (10×10 array) in real time. The conductive core-sheath yarn in the second group of warp and weft yarns ( Figure 11 The black dashed line (the black dashed line) is connected to a regulated DC power supply, forming an embedded electrothermal network. During the experiment, this network continuously outputs a stable thermal field, providing a constant temperature test environment for the pressure sensing unit array.

[0033] To verify the spatial pressure sensing capability of the material, objects of different shapes were placed on the surface of the dual-functional composite fabric, and the pressure sensing array and the electrothermal system were activated simultaneously. Figure 12 As shown, the compressed area of the fabric generates a capacitance signal distribution corresponding to the object's contour, and the electric heating temperature remains stable throughout the process. Comparing adjacent sensing units shows that the area under pressure exhibits a significant capacitance signal jump, which can be used to outline the pressure boundary.

[0034] Examples 2-5 The difference between Examples 2-5 and Example 1 is that when preparing the conductive core-sheath yarn, the core and sheath yarns of 8, 10, 14 and 16 spindles are respectively loaded into the braiding machine in sequence for weaving composite conductive core-sheath yarns. The braiding parameters are the same as those in Example 1. The obtained composite conductive core-sheath yarns are correspondingly recorded as 8-conductive core-sheath yarn, 10-conductive core-sheath yarn, 14-conductive core-sheath yarn and 16-conductive core-sheath yarn.

[0035] The electrical-mechanical synergistic characterization of the sensing unit constructed based on different conductive core-sheath yarns was performed according to the method described in Example 1. The results are as follows: 1) 8-conductive core-sheath yarn: The capacitance response pressure range is 0-100 kPa, and the capacitance change rate is 0-188.4%. Under a pressure of 100 kPa, the response time of the stretching process is 65 ms, and the response time of the recovery process is 81 ms. Under a cyclic compression load of 50 kPa, the sensing unit maintains a stable capacitance signal after 12,000 cycles.

[0036] 2) 10-conductive core-sheath yarn: The capacitance response pressure range is 0-100 kPa, and the capacitance change rate is 0-210.6%. Under a pressure of 100 kPa, the response time of the stretching process is 77 ms, and the response time of the recovery process is 78 ms. Under a cyclic compression load of 50 kPa, the sensing unit maintains a stable capacitance signal after 12,000 cycles.

[0037] 3) 14-conductive core-sheath yarn: The capacitance response pressure range is 0-100 kPa, and the capacitance change rate is 0-229.1%. Under a pressure of 100 kPa, the response time of the stretching process is 86 ms, and the response time of the recovery process is 76 ms. Under a cyclic compression load of 50 kPa, the sensing unit maintains a stable capacitance signal after 12,000 cycles.

[0038] 4) 16-conductive core-sheath yarn: The capacitance response pressure range is 0-100 kPa, and the capacitance change rate is 0-227.5%. Under a pressure of 100 kPa, the response time of the stretching process is 77 ms, and the response time of the recovery process is 93 ms. Under a cyclic compression load of 50 kPa, the sensing unit maintains a stable capacitance signal after 12,000 cycles.

[0039] The pressure sensing performance test results of Examples 1 and 2-5 show that the differences in capacitance signal stability and response time performance of the bimodal composite fabrics are directly related to the number of spindles (i.e., the number of yarns) in the conductive core-sheath yarn. As the number of yarns increases, the diameter of the conductive core-sheath yarn increases, leading to a larger electrode spacing and a significant increase in capacitance. However, when the number of yarns exceeds 12, the optimized conductive contact area stabilizes the capacitance. This structural change results in the samples produced in Examples 2-5 exhibiting weaker compression signal response and response time than the sample produced in Example 1 due to the dynamic imbalance between electrode spacing and contact area.

[0040] 10 cm lengths of each of the different conductive core-sheath yarns prepared in Examples 2-5 were used to test their electrothermal properties. Each 10 cm length of each conductive core-sheath yarn was connected to a regulated DC power supply (at an ambient temperature of approximately 25°C), a voltage of 1.2 V was applied, and the temperature rise characteristics were monitored in real time (at 10-second intervals) using a multi-channel thermocouple. The results showed that the electrothermal temperature of the 8-conductive core-sheath yarn was 40.3°C, the 10-conductive core-sheath yarn was 47.4°C, the 14-conductive core-sheath yarn was 58°C, and the 16-conductive core-sheath yarn was 64.6°C. Combined with the test data from Example 1, it can be seen that the electrothermal temperature increased significantly with the number of yarns. The mechanism is that increasing the number of yarns connected in parallel effectively reduces the overall resistance, thereby increasing the Joule heating effect at the same voltage. This confirms the positive correlation between the number of conductive core-sheath yarns and electrothermal performance.

Claims

1. A method for preparing a smart composite fabric, characterized in that: The steps include: 1) Repeating the process of coating the Tencel yarn with a conductive material layer and drying until the resistance value per unit length of the yarn tends to be stable, thereby obtaining a conductive Tencel yarn; 2) Using a braiding machine, the conductive Tencel yarn is cross-woven to form a core layer structure, and the base yarn is cross-woven to form an outer sheath structure covering the core layer, thereby obtaining a conductive core-sheath yarn; 3) Construct a double-warp and double-weft plain weave system, in which: warp yarn group I and weft yarn group I are both composed of conductive core-sheath yarn; warp yarn group II uses ordinary yarn, and weft yarn group II is composed of conductive core-sheath yarn and ordinary yarn arranged alternately in a set ratio; the two groups of warp and weft yarns are fed synchronously into the loom according to a predetermined ratio, and the smart composite fabric is formed by plain weave interweaving.

2. The method for preparing a smart composite fabric according to claim 1, wherein: In step 1), the thickness of the Tencel yarn is 30-60 D, the conductive material is conductive silver paste, and the coating process is completed by passing the Tencel yarn through an oiler filled with 50-65 wt% conductive silver paste. The drying temperature is 50-80°C and the drying time is 30-60 min.

3. The method for preparing a smart composite fabric according to claim 1, wherein: In step 2), the thickness of the conductive Tencel yarn of the braided core layer structure is 40-60 D and the number of roots is 8 to 16, and the thickness of the base yarn of the braided outer sheath structure is 60-80 D and the number of roots is 8 to 16. The number of roots of the base yarn used is not less than the number of roots of the conductive Tencel yarn; the base yarn is one of high-elastic nylon yarn, polyester yarn, cotton yarn, wool yarn, viscose yarn, and acrylic yarn, or a combination of two.

4. The method for preparing a smart composite fabric according to claim 1, wherein: In step 2), the weaving speed is 5-30 rpm, and the winding speed is 0.5-5 m / min.

5. The method for preparing a smart composite fabric according to claim 1, wherein: In step 3), the warp and weft yarn group I and the warp and weft yarn group II are fed into the loom synchronously at a ratio of 1:5 to 20.

6. The method for preparing a smart composite fabric according to claim 1, wherein: In step 3), the common yarn is one of high-elastic nylon yarn, polyester yarn, cotton yarn, wool yarn, viscose yarn, and acrylic yarn; the weft yarn group II is composed of conductive core-sheath yarn and common yarn arranged alternately in a ratio of 1:3 to 20.

7. The method for preparing a smart composite fabric according to claim 1, wherein: In step 3), the warp yarn group I and the weft yarn group I are arranged in an equidistant pattern, wherein the lateral and longitudinal spacings of adjacent conductive core sheath yarns are controlled at 1-10 cm, and the number of warp yarns and the number of weft yarns are configured in equal quantities of 2-100, thereby constructing an array-type sensing matrix of 2×2 to 100×100.

8. The method for preparing a smart composite fabric according to claim 1, wherein: In step 3), the spacing between adjacent conductive core-sheath yarns in weft yarn group II is controlled to be 1-10 cm.

9. An intelligent composite fabric with both pressure sensing and thermal response functions, characterized in that: It is prepared based on the preparation method described in any one of claims 1-8. The warp yarn group I and the weft yarn group I are orthogonally woven to form a distributed sensing array. Each interweaving point in the array constitutes a discrete pressure sensing unit to realize spatial dynamic monitoring of contact pressure; the conductive core sheath yarn embedded in the weft yarn group II forms an independent temperature control module based on the Joule heating effect after being energized.

10. Application of the intelligent composite fabric with both pressure sensing and thermal response functions as claimed in claim 9 in the fields of medical monitoring and sports monitoring.

Images