Fabric-based self-energized infrared hidden mark based on friction nano-generator, preparation method thereof, and self-energized fabric and intelligent fabric comprising mark

Abstract

The invention discloses a fabric-based self-energized infrared hidden mark based on a friction nano-generator, a preparation method of the fabric-based self-energized infrared hidden mark, and a self-energized fabric and an intelligent fabric comprising the mark, and belongs to the technical field of flexible electronics and intelligent textiles. The fabric is formed by weaving two kinds of core-sheath structure functional yarns (respectively used as a friction positive electrode and a friction negative electrode), and a miniature infrared light-emitting diode is directly integrated between yarn conductive cores. A compact hydrophobic packaging layer is applied to the surface of the fabric, so that mechanical energy of human motion can be continuously converted into electric energy in field environments such as rain, snow, high humidity and the like, and an infrared light emitting diode is driven to emit 850-950 nm hidden light signals which are invisible to human eyes and can be clearly captured by infrared detection equipment. The preparation process only needs the steps of conventional spinning, dip-coating and curing, the cost is low, and large-area production can be realized. The system does not need a battery, has the characteristics of self energy supply, high concealment, water resistance, durability, wearing comfort and the like, and can be applied to military camouflage, outdoor rescue, night identity recognition and other scenes.

Description

Technical Field

[0001] This invention relates to the field of flexible electronics and smart textile technology, and in particular to a self-powered fabric based on a triboelectric nanogenerator (TENG). More specifically, it relates to a smart fabric and its preparation method that can continuously generate electricity in complex outdoor environments, drive light-emitting diodes (LEDs) to form infrared covert markings, and has waterproof and durable properties. Background Technology

[0002] With the rapid development of the Internet of Things, wearable devices, and individual soldier combat systems, the demand for flexible wearable electronic devices capable of operating independently without external power supply is increasing. Triboelectric nanogenerators (TENGs), as an emerging technology that can efficiently harvest minute mechanical energy from the environment (such as human movement, wind, and water droplet impacts) and convert it into electrical energy, offer a feasible solution to the energy problem of wearable devices. Among them, fabric-based TENGs, which combine TENG technology with fabrics, have become a current research hotspot due to their lightweight, softness, breathability, and wearability.

[0003] In specialized applications such as military, rescue, and outdoor exploration, identification and positioning at night or in adverse weather conditions are crucial. Traditional visible light tags are easily detected, while infrared tags offer superior concealment. Current infrared tags largely rely on battery-powered infrared LEDs or infrared radiating materials, which suffer from limited energy, the need for regular battery replacements, bulky equipment, and poor reliability in humid environments. Therefore, developing a self-powered, long-lasting, and highly concealed infrared tagging system has significant application value.

[0004] Currently, significant progress has been made in the research of fabric-based TENGs. Researchers have improved their output performance by optimizing fabric structures (such as one-dimensional yarns, two-dimensional planes, and three-dimensional spacer structures) and material selection. For example, using core-sheath structure yarns and introducing two-dimensional materials (such as graphene and MoS2) as electrodes or performance enhancement layers has enabled the driving of hundreds of LEDs or the power supply of small electronic devices. However, existing fabric-based TENGs still face the following challenges: (1) Poor environmental adaptability: The performance of most TENGs drops sharply in humid environments because water molecules form a conductive layer on the friction surface, causing rapid dissipation of triboelectric charge, which limits their practical application in outdoor environments such as rain and snow. (2) Low functional integration: Existing research focuses on energy harvesting itself, while self-powered systems that efficiently integrate TENGs with specific functions (such as infrared covert marking) are still immature. How to use the weak electrical energy generated by TENGs to stably drive functional modules and form signals that can be recognized by specific devices (such as infrared thermal imagers) is a technical challenge. (3) Complex preparation process: The preparation process of some high-performance TENGs depends on complex material synthesis or precise micro-nano processing technology, which is not conducive to large-scale, low-cost production and limits their promotion and application.

[0005] Therefore, there is an urgent need for a self-powered fabric-based TENG technology solution that has a simple preparation process, strong environmental tolerance, and can be closely integrated with infrared marking functions. Summary of the Invention

[0006] To address the problems existing in the background technology, the purpose of this invention is to overcome the shortcomings of existing fabric-based TENGs, such as poor performance in humid environments, limited functionality, and complex manufacturing processes, and to provide a TENG-based self-powered infrared covert identification fabric and its preparation method. This invention, by employing conductive core-sheath structure yarns, hydrophobic functional coatings, and electrothermal effect materials, achieves a smart fabric that can stably generate electricity in humid outdoor environments and drive an IR-LED to emit covert light signals that can be identified by infrared detection devices.

[0007] To achieve the above objectives, the present invention adopts the following technical solution: A fabric-based self-powered infrared stealth tag based on a triboelectric nanogenerator, comprising: (1) Fabric matrix: It is composed of at least two different functional yarns through weaving or knitting processes to form a triboelectric energy harvesting structure; (2) First functional yarn: as a triboelectric positive electrode and a conductive electrode, its structure is a core-sheath structure, which includes a conductive core and a first triboelectric layer wrapped around it; (3) Second functional yarn: As a triboelectric negative electrode and a conductive electrode, its structure is a core-sheath structure, which includes a conductive core and a second friction layer wrapped around it; the materials of the first friction layer and the second friction layer have a significant difference in electronic affinity to generate efficient charge transfer during contact separation; (4) Infrared marking unit: The conductive core of the first functional yarn and the second functional yarn is electrically connected. This unit is at least one infrared light-emitting diode (IR-LED) used to directly convert the electrical energy generated by TENG into infrared light signals of a specific wavelength. (5) Hydrophobic encapsulation layer: uniformly coated on the surface of the fabric substrate to form a dense and flexible waterproof protective layer to isolate the influence of external moisture on triboelectric properties.

[0008] In the above technical solution, the conductive core is preferably a material with good conductivity and flexibility, such as polypyrrole (PPy) coated yarn, silver wire, stainless steel wire or carbon nanotube fiber, to ensure effective charge conduction.

[0009] In the above technical solution, the first friction layer is preferably a material such as nylon or wool that easily loses electrons in the friction sequence. The second friction layer is preferably a material such as polytetrafluoroethylene (PTFE) or polydimethylsiloxane (PDMS) that easily gains electrons in the friction sequence, thereby maximizing the triboelectric charge density.

[0010] In the above technical solution, at least one of the first friction layer and the second friction layer includes a jungle camouflage pattern.

[0011] In the above technical solution, the emission wavelength of the infrared marking unit (IR-LED) is preferably in the range of 850nm to 950nm. This band is invisible to the human eye, but can be efficiently captured by standard infrared night vision or detection equipment, thereby realizing the concealed marking function.

[0012] In the above technical solution, the hydrophobic encapsulation layer is preferably waterborne polyurethane (WPU) or polydimethylsiloxane (PDMS), which forms a uniform, continuous and complete waterproof film on the fabric surface through dip coating or scraping coating process, ensuring that the fabric has excellent moisture resistance while maintaining flexibility and breathability.

[0013] This invention also provides a method for preparing a self-powered infrared covert marking fabric, which includes the following steps: (1) Preparation of conductive yarn: A layer of polypyrrole (PPy) is polymerized in situ on the surface of ordinary fabric yarn (such as cotton yarn and polyester yarn) using chemical oxidation polymerization method to form a conductive yarn with excellent conductivity as the core yarn of subsequent functional yarn.

[0014] (2) Preparation of functional yarns: The conductive yarn is used as the core, and a first friction layer material (such as nylon fiber) and a second friction layer material (such as PTFE fiber) are wrapped around it by high-speed weaving, precision winding or coating, respectively, to prepare a first functional yarn and a second functional yarn with opposite friction polarities.

[0015] (3) Fabric matrix weaving and LED integration: The prepared first and second functional yarns are woven into a fabric matrix according to a preset pattern and weaving method (such as plain weave, knitted rib, etc.) by an industrial or manual weaving machine. During the weaving process, the electrodes of the micro IR-LED array are precisely connected to the conductive cores of adjacent different functional yarns through conductive adhesive or micro-welding technology to form a preset identification pattern (such as letters, numbers or specific symbols).

[0016] (4) Hydrophobic encapsulation treatment: The woven fabric substrate with integrated LEDs is immersed in a water-based polyurethane (WPU) solution of a specific concentration to ensure that the solution fully penetrates and covers the fabric surface and LED solder joints. Then it is taken out and dried and cured in a vacuum oven at a specific temperature (e.g., 80°C) to form a uniform and dense hydrophobic encapsulation layer.

[0017] In the above technical solution, the method of the present invention further includes the following steps: when preparing the first friction layer and the second friction layer, a jungle camouflage pattern is pre-printed on the fiber bundle using segmented dyeing or printing technology.

[0018] The present invention also provides a self-powered fabric based on a triboelectric nanogenerator, which includes the aforementioned fabric-based self-powered infrared covert tag based on a triboelectric nanogenerator.

[0019] The present invention further provides a smart fabric, which includes the aforementioned fabric-based self-powered infrared concealed tag based on a triboelectric nanogenerator, wherein the smart fabric is manifested as close-fitting clothing, wristband or armband.

[0020] The present invention has the following beneficial effects: (1) Excellent environmental adaptability: By forming a dense WPU or PDMS hydrophobic encapsulation layer on the fabric surface, it effectively prevents water such as rain and sweat from penetrating, fundamentally solving the problem of leakage of triboelectric charge due to moisture, and ensuring that TENG can still output electrical energy stably and efficiently in outdoor environments with humidity as high as 80% or even higher.

[0021] (2) High-efficiency self-powered and infrared light signal integration: This invention seamlessly integrates the TENG energy harvesting unit and the IR-LED light-emitting unit onto a single fabric platform. Driven by minute mechanical energy such as human movement, the high-voltage, low-current pulsed power generated by the TENG can be effectively utilized by the low-power IR-LED, directly illuminating it and emitting infrared light of a specific wavelength. This infrared light signal is invisible to the human eye but can be clearly captured by infrared detection equipment, realizing a complete self-powered technology chain of "energy harvesting - light signal emission - covert identification".

[0022] (3) The preparation process is simple and low-cost: The technologies used in this invention, such as in-situ polymerization, fiber coating, conventional textile processes and dip coating curing, are all mature industrial technologies. The raw materials (such as cotton yarn, nylon, PTFE, PPy) are inexpensive and easy to obtain, which makes the smart fabric have the potential for large-scale, low-cost production, laying the foundation for the widespread application of wearable self-powered devices.

[0023] (4) Superior wearability and durability: The fabric matrix itself retains the softness, breathability, and comfort of traditional textiles, meeting the requirements for long-term wear. The core-sheath structure effectively protects the fragile internal conductive core, preventing it from breaking under repeated deformation. At the same time, the external hydrophobic encapsulation layer is not only waterproof but also significantly improves the fabric's abrasion resistance and chemical stability, ensuring that the device maintains stable performance for a long time under harsh operating conditions. Attached Figure Description

[0024] To more clearly illustrate the technical solutions of the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are merely some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without any creative effort.

[0025] Figure 1 This is a schematic diagram of the core-sheath structure yarn used in this invention; Figure 2 This is a schematic diagram of the contact-separation working mode of the fabric-based TENG of the present invention; Figure 3 This is a comparative diagram showing the effect of the hydrophobic layer on the output performance of TENG under different humidity levels; Figure 4 This is a schematic diagram illustrating the application of the fabric-based TENG of the present invention, which drives an LED array to emit light through beating or deformation. Figure 5 This is a schematic diagram of the electron cloud overlap model of triboelectric charging; and Figure 6 This is a schematic diagram of the fabric-based self-powered infrared concealed tag based on a triboelectric nanogenerator used in this invention. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0027] Example 1: Infrared LED Marking Fabric Based on PPy Conductive Core and WPU Hydrophobic Encapsulation This embodiment aims to illustrate in detail the preparation and performance verification of a self-powered fabric that generates covert light signals by driving infrared LEDs (IR-LEDs).

[0028] 1. Fabric structure and working principle like Figure 1 and 6 As shown, the fabric in this embodiment is woven from yarns with a core-sheath structure. A conductive core (e.g., PPy-coated cotton yarn) is tightly wrapped with an insulating polymer (e.g., nylon or PTFE) serving as a friction layer. By interweaving two functional yarns with opposite frictional polarities (e.g., nylon-wrapped conductive yarn as the positive electrode and PTFE-wrapped conductive yarn as the negative electrode), a fabric base TENG with numerous microscopic contact points is formed. When the fabric deforms due to external mechanical forces (e.g., pressing, bending, stretching), close contact and rapid separation occur between different friction layers within the fabric, such as... Figure 2 The contact-separation working mode is shown.

[0029] According to the triboelectric effect, the nylon layer, with weaker electron affinity, loses electrons and becomes positively charged, while the PTFE layer, with stronger electron affinity, gains electrons and becomes negatively charged. This macroscopic charge separation establishes a significant potential difference between the two conductive cores. To balance this potential difference, electrons flow directionally in the external circuit (i.e., the IR-LED) connecting the two conductive cores, forming a pulsed current. This process repeats continuously and efficiently converts weak mechanical energy into electrical energy, which is released as infrared light, thus illuminating the LED. The microscopic mechanism of triboelectric charging can be explained by the electron cloud overlap model. Figure 5 That is, at the moment of contact, the electron clouds of atoms in different materials overlap, the potential barrier is lowered, and electrons are prompted to jump from one atomic orbital to another, forming a stable surface static charge after separation.

[0030] 2. Preparation method The specific preparation steps are as follows: (1) Preparation of PPy conductive cotton yarn: Commercially available pure cotton yarn (e.g., 40 count) was immersed in 20 mL of deionized water containing 0.4 g of ferric p-toluenesulfonate as a catalyst, ensuring complete wetting of the yarn. Subsequently, 1.6 g of pyrrole monomer was added, and an in-situ chemical oxidative polymerization reaction was carried out in an ice-water bath for 24 hours. After the reaction, the yarn was repeatedly rinsed with anhydrous ethanol and deionized water to remove unreacted monomers and byproducts, and finally dried in an 80°C oven to obtain black conductive cotton yarn with a uniformly dense layer of PPy particles on the surface.

[0031] (2) Preparation of functional yarns: The above-mentioned PPy conductive cotton yarn is used as the core yarn. Using a high-speed braiding machine or precision winding equipment, nylon 66 fiber bundles and PTFE fiber bundles are tightly and evenly wrapped around the outside to make two core-sheath structure functional yarns with opposite friction polarities. Ensure that the outer fiber layer is completely covered and that no conductive core is exposed.

[0032] (3) Fabric weaving and LED integration: An industrial-grade double-needle flat knitting machine is used to weft-knit the two functional yarns in a 1x1 rib structure to form a fabric matrix with excellent elasticity and three-dimensional contact capability. During the weaving process, several miniature patch-type IR-LEDs (center wavelength 940nm) are arranged in an array on the fabric according to a preset marking pattern (such as the letters "SOS"). Using conductive silver paste or micro solder points, the positive and negative electrodes of each LED are precisely connected to the conductive cores of the adjacent nylon functional yarn and PTFE functional yarn, respectively.

[0033] (4) WPU hydrophobic encapsulation: Prepare a mixed solution of deionized water and WPU emulsion at a mass ratio of 5:1. Immerse the woven fabric completely in the solution and treat it with ultrasound for 15 minutes to ensure that the WPU emulsion can fully penetrate into the fiber gaps and encapsulate the LED solder joints. Remove the fabric, gently scrape off the excess liquid on the surface with a scraper, and then dry and cure it in a vacuum oven at 80°C for 12 hours to finally form a transparent, flexible and dense WPU waterproof encapsulation layer on the surface of the fabric.

[0034] 3. Performance Testing and Results A 30mm x 30mm fabric sample was fixed on a linear motor-driven test platform and subjected to a periodic pressure of 15N at a frequency of 3Hz to simulate typical stress conditions during human movement. In a dry environment (20% relative humidity), the peak open-circuit voltage of the TENG was measured to be 41.47V using an oscilloscope. Subsequently, the sample was placed in a high-humidity environment (80% relative humidity) for the same test. Figure 3As shown, thanks to the effective protection of the WPU encapsulation layer, the peak output voltage of the TENG remains at 32.67V, retaining approximately 78.78% of its performance. In contrast, the control sample without WPU encapsulation experiences a sharp voltage drop to 5.96V in high humidity environments, retaining only 21.22% of its performance, rendering it almost unusable. In a dark environment, by repeatedly patting or stretching the fabric, an infrared night vision device can clearly observe that the preset patterned IR-LED array flashes synchronously with each mechanical deformation, forming a dynamic infrared light signal (such as...) that can be stably identified by long-distance detection devices. Figure 4 The application scenarios shown demonstrate its effectiveness as a self-powered infrared covert marker.

[0035] Example 2: Enhanced Infrared Marking Fabric with Integrated Energy Storage Unit This embodiment aims to solve the problem of unstable TENG pulse output energy, which may lead to uneven LED flickering brightness or interruption. It achieves more stable and longer infrared signal output by integrating an energy storage unit.

[0036] 1. Structure and Principle The basic fabric structure in this embodiment is the same as in Embodiment 1. The key difference lies in the circuit design: an energy storage management module consisting of a miniature bridge rectifier and a flexible textile supercapacitor (T-Supercap) is added between the output of the TENG and the IR-LED. The AC pulse power generated by the TENG is first converted into DC power by the rectifier, and then charges the T-Supercap. When the voltage of the capacitor reaches the IR-LED's turn-on threshold (e.g., 1.5V), the stored energy can provide the LED with a relatively stable and longer-lasting driving current, enabling it to emit stable or continuously flashing infrared light, significantly improving the detectability and reliability of the signal in practical applications.

[0037] 2. Preparation method The preparation method is basically the same as in Example 1, with the main difference being the circuit integration in step 3: integration of fabric weaving and energy storage circuitry. While weaving the fabric matrix, a miniature flexible T-Supercap (e.g., a textile capacitor using graphene as electrodes and PVA / H2SO4 gel as electrolyte) and a bridge rectifier circuit are integrated into the non-functional area of ​​the fabric. The AC input of the rectifier is connected to the two conductive cores of the TENG, the DC output is connected to the positive and negative terminals of the T-Supercap, and the output of the T-Supercap is connected to the IR-LED array. All connection points are fixed with conductive adhesive and locally encapsulated with WPU to ensure circuit stability and water resistance.

[0038] 3. Performance Testing and Results The prepared integrated energy storage fabric was subjected to continuous mechanical excitation (e.g., continuous tapping at a frequency of approximately 4-6 Hz and a force of approximately 7-10 N). The voltage across the T-Supercap was monitored in real time using a multimeter. Experiments showed that an energy storage unit consisting of nine T-Supercaps connected in series could be charged to 10V by the TENG within approximately 250 seconds. After charging, even after the mechanical excitation was stopped, the energy storage unit could independently drive the IR-LED array to emit light continuously for several minutes. Observation with an infrared thermal imager showed that the infrared light signal emitted by the LED was uniform in intensity and had no obvious flicker, with signal quality far superior to the direct driving method without an energy storage unit in Example 1. This example demonstrates that by integrating an energy storage module, the energy output characteristics of the TENG can be effectively optimized, achieving a more practical and reliable self-powered infrared identification function.

[0039] Example 3: High-sensitivity infrared marking fabric based on a three-dimensional spacer fabric structure This embodiment aims to improve the response sensitivity of TENG to weak mechanical stimuli and enhance its output performance by optimizing the three-dimensional geometry of the fabric.

[0040] 1. Structure and Principle This embodiment uses a 3D spacer fabric as the matrix for TENG. This fabric consists of two independent fabric layers, upper and lower, and an intermediate monofilament or multifilament layer connecting the two layers. The upper fabric layer serves as the positive electrode for triboelectric charging (e.g., a nylon surface layer), and the lower fabric layer serves as the negative electrode (e.g., a PTFE surface layer). Conductive electrodes (e.g., silver nanowire coatings) are laminated to the inner sides of both fabric layers. The intermediate spacer yarn (e.g., polyester monofilament) provides excellent resilience and a fixed contact-separation distance. When subjected to vertical pressure, the upper and lower fabric layers come into contact; after the pressure is removed, the elasticity of the spacer yarn causes the two layers to separate rapidly, thus achieving efficient and stable triboelectric energy conversion. This structure increases the effective contact area and ensures sufficient charge separation distance, thereby significantly improving open-circuit voltage and short-circuit current.

[0041] 2. Preparation method (1) Preparation of functional fabric layers: A layer of conductive silver paste was coated onto two separate polyester fabrics using screen printing technology as electrodes. After drying, nylon solution and PTFE dispersion were coated onto the electrode surfaces respectively, and after curing, triboelectric positive and negative electrode layers were formed.

[0042] (2) Weaving of three-dimensional fabric: Using a double needle bed warp knitting machine, the two functional fabric layers mentioned above are used as the upper and lower surface layers, and high-elastic polyester monofilament is used as the middle connecting yarn to weave into an integrated three-dimensional spacer fabric.

[0043] (3) LED integration and packaging: The electrodes of the IR-LED array are connected to the conductive silver paste electrodes of the upper and lower fabric layers respectively. Finally, the whole hydrophobic encapsulation is performed using the same WPU dip coating process as in Example 1.

[0044] 3. Performance Testing and Results Under the same 15N, 3Hz pressure test conditions, the open-circuit voltage of the three-dimensional spacer fabric TENG prepared in this embodiment can reach 136V, and the peak short-circuit current reaches 1.2μA. Compared with the plain weave fabric structure of Embodiment 1, its output power density is increased by nearly 50%. Under weak excitation (such as slight touch or air flow), the IR-LED can be observed to flicker slightly, showing higher energy conversion efficiency and sensitivity, making it more suitable for harvesting energy generated by unconscious slight human movements.

[0045] Example 4: Infrared Marking Fabric Based on Composite Functional Yarn Reinforced with Two-Dimensional Materials This embodiment aims to further enhance the charge generation and retention capabilities of TENG by introducing two-dimensional materials into the friction layer, thereby improving its output performance and durability.

[0046] 1. Structure and Principle In the fabrication of the functional yarn in this embodiment, a two-dimensional material, such as molybdenum disulfide (MoS2) nanosheets, is doped into the friction layer material. MoS2 possesses excellent dielectric properties and charge trapping capabilities, effectively increasing the charge density on the friction layer surface and mitigating natural charge dissipation. When the MoS2-containing composite material is used as the negative electrode friction layer, it generates and maintains a higher surface charge density upon contact and separation from the positive electrode friction layer (such as nylon), thereby significantly improving the output voltage and power of the TENG.

[0047] 2. Preparation method (1) Preparation of composite friction material: MoS2 aqueous dispersion with a concentration of 0.5 g / L was mixed with polyvinyl alcohol (PVA) solution at a volume ratio of 1:1 to prepare PVA / MoS2 composite gel.

[0048] (2) Preparation of functional yarns: PPy conductive cotton yarn is used as the core yarn. The positive electrode functional yarn is wrapped with nylon fiber. The negative electrode functional yarn is prepared by dip coating-lifting process, which uniformly coats the surface of the core yarn with the above-mentioned PVA / MoS2 composite gel, and forms a composite friction layer after drying.

[0049] (3) Fabric preparation and encapsulation: The subsequent fabric weaving, LED integration and hydrophobic encapsulation steps are the same as in Example 1.

[0050] 3. Performance Testing and Results Under pressure testing conditions of 22N and 5-7Hz, the TENG fabric prepared in this embodiment achieved a peak open-circuit voltage of 1068V and a power density of 14.64W / m², significantly outperforming the control group without MoS2. This fabric was able to simultaneously illuminate over 200 commercially available LEDs connected in series, demonstrating its powerful energy output capability. Furthermore, after three months of continuous use, its performance remained above 45% of its peak value, exhibiting excellent long-term stability and durability.

[0051] Example 5: Skin-contact infrared marking fabric based on single-electrode working mode This embodiment aims to develop a single-electrode TENG fabric with a simpler structure that can generate electricity directly through friction with human skin, suitable for making wearable devices such as underwear or armbands.

[0052] 1. Structure and Principle The TENG fabric in this embodiment contains only one type of functional yarn, with a structure consisting of a conductive core (such as silver fiber yarn) covered by a friction layer (such as PDMS). When the fabric comes into contact with and moves relative to human skin (serving as a moving friction electrode and charge reference surface), the PDMS surface acquires a negative charge due to friction, while the skin surface acquires a positive charge. When the skin separates from the fabric, the potential difference drives electrons to flow in the loop formed between the conductive core and the ground (through the human body), thereby generating electrical energy to drive the IR-LED. This mode eliminates the need for paired friction electrodes, has a simple structure, and is well-suited for wearable applications.

[0053] 2. Preparation method (1) Preparation of functional yarn: commercially available silver fiber conductive yarn is immersed in liquid PDMS prepolymer and a uniform PDMS friction layer is formed on its surface by lifting and heat curing (100°C, 2 hours).

[0054] (2) Fabric preparation and circuit connection: The functional yarn is woven into a fabric form such as a wristband or armband. One end of the IR-LED is connected to the conductive yarn of the fabric, and the other end is in good contact with human skin through a conductive cloth patch to form a single electrode working circuit.

[0055] (3) Local encapsulation: WPU is used only for LED connection points and circuit parts to protect the circuit while maintaining direct contact between the fabric body and the skin.

[0056] 3. Performance Testing and Results The fabricated armband is worn on the arm. During walking or arm swinging, the friction between the fabric and skin generates enough electrical energy to cause the IR-LED to emit a flashing signal detectable by infrared devices. Tests show that under normal walking conditions, the generated open-circuit voltage can reach 15V, sufficient to drive a single IR-LED. This embodiment demonstrates the feasibility of TENG achieving self-powered identification with a minimally simplistic structure, particularly suitable for wearable scenarios requiring close contact with the body.

[0057] Example 6: Smart Fabric with Dual Camouflage Functions of Visible Light and Infrared Light This embodiment, based on the self-powered infrared identification, further integrates visible light camouflage functionality to meet higher levels of concealment requirements.

[0058] 1. Structure and Principle The innovation of this embodiment lies in the design of the friction layer. By introducing tunable structural colors or dyes into the friction layer material, the fabric displays a camouflage pattern under visible light that matches a specific environment (such as a jungle or desert). Simultaneously, its internal TENG structure can still drive invisible IR-LEDs to emit light when mechanically stimulated, achieving identification in the infrared band. This design gives the fabric both concealment and identification capabilities in the visible and infrared spectral dimensions.

[0059] 2. Preparation method (1) Preparation of visible light camouflage functional yarn: When preparing the nylon and PTFE friction layer, segmented dyeing or printing technology is used to pre-print jungle camouflage patterns (such as green, brown, and black) onto the fiber bundles. Subsequently, these fiber bundles with camouflage patterns are used to wrap the conductive core to make a functional yarn with visible light camouflage effect.

[0060] (2) Fabric preparation and LED integration: The above-mentioned camouflage functional yarns are woven according to a specific camouflage texture layout to form a macroscopically continuous camouflage pattern fabric. The integration method of IR-LED is the same as in Example 1.

[0061] (3) Hydrophobic encapsulation: Use transparent WPU or PDMS for hydrophobic encapsulation to ensure that the encapsulation layer does not affect the camouflage color and pattern of the underlying fabric.

[0062] 3. Performance Testing and Results The fabric produced exhibits a realistic jungle camouflage effect under sunlight, making it difficult to distinguish with the naked eye. Simultaneously, at night or when observed through infrared detection equipment, its internal IR-LED array emits a preset infrared signal when struck or squeezed. This embodiment successfully integrates visible light passive camouflage with self-powered active infrared identification, providing a novel technological approach for developing next-generation multimodal intelligent concealment clothing.

[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

[0064] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0065] The embodiments described above are merely illustrative of several implementation methods of this application, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this application, and these all fall within the protection scope of this application. Therefore, the protection scope of this patent application should be determined by the appended claims.

Claims

1. A fabric-based self-powered infrared covert tag based on a triboelectric nanogenerator, characterized in that, include: (1) The fabric matrix is ​​composed of a first functional yarn and a second functional yarn through a weaving or knitting process, wherein the first functional yarn and the second functional yarn serve as the positive and negative electrodes of the triboelectric charge, respectively. (2) The first functional yarn has a core-sheath structure, with a first friction layer wrapped around its conductive core. The material of the first friction layer is prone to losing electrons in the friction sequence. (3) The second functional yarn is a core-sheath structure, with a second friction layer wrapped around its conductive core. The material of the second friction layer is easy to gain electrons in the friction sequence and has a significant difference in electron affinity with the material of the first friction layer. (4) An infrared identification unit, comprising at least one infrared light-emitting diode (IR-LED) with an emission wavelength of 850-950 nm, wherein the positive and negative electrodes of the IR-LED are electrically connected to the conductive cores of the first functional yarn and the second functional yarn, respectively, to form a concealed light signal that can be identified by an infrared detection device. (5) A hydrophobic encapsulation layer is uniformly covered on the fabric substrate and the surface of the IR-LED solder joints to isolate external moisture and maintain the stability of triboelectric charge.

2. The fabric-based self-powered infrared concealed tag according to claim 1, characterized in that: The conductive core is one or more of the following: polypyrrole (PPy) coated yarn, silver wire, stainless steel wire, or carbon nanotube fiber.

3. The fabric-based self-powered infrared concealed tag according to claim 1, characterized in that: The first friction layer material is nylon or wool; the second friction layer material is polytetrafluoroethylene (PTFE) or polydimethylsiloxane (PDMS).

4. The fabric-based self-powered infrared concealed tag according to claim 3, characterized in that: At least one of the first friction layer and the second friction layer includes a jungle camouflage pattern.

5. The fabric-based self-powered infrared concealed tag according to claim 1, characterized in that: The hydrophobic encapsulation layer is waterborne polyurethane (WPU) or PDMS, which forms a uniform, continuous, and transparent waterproof film by dip coating or scraping.

6. The fabric-based self-powered infrared concealed tag according to any one of claims 1 to 5, characterized in that: The fabric matrix is ​​a plain weave, rib weave, or three-dimensional spaced fabric structure to ensure contact-separation efficiency under repeated deformation.

7. A method for preparing a fabric-based self-powered infrared covert tag based on a triboelectric nanogenerator as described in any one of claims 1 to 6, characterized in that, Includes the following steps: (1) Preparation of conductive yarn: Polypyrrole (PPy) is polymerized in situ on the surface of ordinary yarn by chemical oxidation polymerization to obtain conductive core; (2) Preparation of functional yarn: Using a conductive core as the axis, the first friction layer and the second friction layer are respectively wrapped by high-speed braiding or winding process to obtain the first functional yarn and the second functional yarn; (3) Fabric forming and LED integration: Two functional yarns are woven into a fabric according to a preset pattern, and the IR-LED electrode is electrically connected to the conductive core of the adjacent functional yarn during the weaving process. (4) Hydrophobic encapsulation: Immerse the fabric obtained in step (3) into WPU or PDMS solution, remove it and vacuum dry and cure it at 60–100°C to form a dense hydrophobic encapsulation layer.

8. The method according to claim 7, characterized in that, Further steps include: In preparing the first and second friction layers, a segmented dyeing or printing technique is used to pre-print the jungle camouflage pattern onto the fiber bundle.

9. A self-powered fabric based on a triboelectric nanogenerator, characterized in that, The fabric-based self-powered infrared covert tag based on any one of claims 1 to 6 includes the aforementioned claims 1 to 6.

10. A smart fabric, characterized in that, The smart fabric-based self-powered infrared covert tag based on a triboelectric nanogenerator, as described in any one of claims 1 to 6, is embodied in clothing, wristbands, or armbands.

Images