Electrostatic spinning technology-based pyroelectric intelligent induction skin one-step method preparation process

Abstract

The invention discloses a pyroelectric intelligent sensing skin one-step method preparation process based on an electrostatic spinning technology, which comprises the following steps: dissolving a pyroelectric material and a high-conductivity nano dopant in a mixed solvent, uniformly stirring, standing and defoaming to obtain a spinning solution; injecting the spinning solution into an electrostatic spinning device, taking a flexible substrate as a receiving substrate, and performing electrostatic spinning under the action of a high-voltage electrostatic field, so that the spinning solution forms a high-content pyroelectric activity beta crystalline phase in situ while being stretched and cured into nanofibers, and directly deposits on the surface of the flexible substrate to form a nanofiber functional layer; the electrode layer is prepared on the surface of the nanofiber functional layer, an electric signal is led out, and the pyroelectric intelligent induction skin is obtained, according to the technology, preparation of the nanofiber skin, in-situ polarization of the beta crystal phase and firm combination with the substrate are integrated in a single procedure, the technological process is simplified, and the interface bonding strength and the pyroelectric performance are improved.

Description

Technical Field

[0001] This invention relates to the field of synthetic leather technology, specifically to a one-step process for preparing pyroelectric intelligent sensing skin based on electrospinning technology. Background Technology

[0002] Currently, flexible electronics and human-computer interfaces are developing towards thinner, more integrable, and lower-power consumption. Pyroelectric materials can directly convert temperature changes into electrical signals, providing an ideal path for passive, self-driven sensing. Traditional pyroelectric smart sensing skins typically require separate skin fabrication followed by additional physical stretching or high-voltage polarization to induce the formation of a higher-order β-crystalline phase. Finally, they must be bonded to a flexible substrate using adhesives, resulting in problems such as weak interfacial adhesion, poor flexibility, and complex processes. Summary of the Invention

[0003] To address the problems of complex fabrication processes, weak interfacial bonding, and poor flexibility in existing pyroelectric intelligent sensing skins, this invention provides a one-step fabrication process for pyroelectric intelligent sensing skins based on electrospinning technology. This process integrates the preparation of nanofiber skins, in-situ polarization of the β-crystal phase, and strong bonding with the substrate into a single step, simplifying the process flow and improving interfacial bonding strength and pyroelectric performance.

[0004] To achieve the above objectives, the present invention provides a one-step process for preparing pyroelectric intelligent sensing skin based on electrospinning technology, comprising the following steps: (1) Preparation of precursor solution: Dissolve pyroelectric material and highly conductive nano-dopant in a mixed solvent, stir evenly, let stand to remove bubbles, and obtain spinning solution; (2) One-step electrospinning and polarization: The spinning solution is injected into the electrospinning device, and a flexible substrate is used as the receiving substrate. Electrospinning is carried out under the action of a high voltage electrostatic field, so that the spinning solution is stretched and solidified into nanofibers while forming a high content of pyroelectric active β crystal phase in situ, and directly deposited on the surface of the flexible substrate to form a nanofiber functional layer. (3) Preparation of electrode layer: An electrode layer is prepared on the surface of the nanofiber functional layer to extract electrical signals and obtain the pyroelectric smart sensing skin.

[0005] Furthermore, in step (1), the pyroelectric material is a PVDF-TrFE copolymer; the highly conductive nano-dopant is one or more of nano-graphene, carbon nanotubes or conductive metal nanoparticles; and the mixed solvent is composed of DMF and acetone in a volume ratio of 4:1.

[0006] Furthermore, in the spinning solution described in step (1), the solid content of the pyroelectric material is 12%-18%; the mass fraction of the highly conductive nano-dopant is 0.1-5% of the mass of the pyroelectric material.

[0007] Furthermore, in step (2), the flexible substrate is a microfiber skin; the electrospinning process parameters are: voltage 10-30kV, receiving distance 10-20cm, and spinning solution push rate 0.5-2mL / h.

[0008] Furthermore, in step (3), the electrode layer is prepared by any one of magnetron sputtering or coating conductive silver paste / silver nanowires.

[0009] Furthermore, in the nanofiber functional layer, the PVDF-TrFE / nano-doped composite nanofibers have a three-dimensional network porous structure.

[0010] Furthermore, the nanofiber functional layer is physically interwoven or mechanically interlocked with the flexible substrate at the interface through in-situ electrospinning growth.

[0011] This invention provides a one-step fabrication process for pyroelectric intelligent sensing skin based on electrospinning technology. The core innovation lies in proposing a one-step integrated electrospinning process that combines the traditional multi-step pre-film preparation and post-processing steps (such as stretching, polarization, and bonding) into a single process. This allows for the simultaneous formation of functional crystalline phases and interfacial bonding while fabricating the nanofiber skin. The beneficial technical effects are specifically reflected in the following three aspects: 1. Integrated process. By precisely controlling the electrospinning parameters (such as voltage, distance, and solvent ratio), PVDF-TrFE nanofibers can directly form a highly sensitive pyroelectric active β-crystal phase while being deposited into a web, achieving functionalization upon preparation without the need for subsequent polarization or heat treatment.

[0012] 2. Integrated Interface: Nanofibers are directly spun onto the surface of the microfiber skin, forming a physically interwoven structure, rather than being bonded with adhesives as in traditional processes. This bonding makes the skin stronger, more flexible, less prone to delamination, and provides more stable signal transmission.

[0013] 3. Material Synergy. PVDF-TrFE copolymer with better crystallinity is selected and combined with DMF / acetone mixed solvent. Taking advantage of the fast drying properties of acetone and the slow drying properties of DMF, β crystals are efficiently induced during the fiber stretching and curing process. At the same time, a trace amount of nano-graphene is incorporated, which not only improves the efficiency of the spinning electric field, but also enhances the pyroelectric effect, making the skin more sensitive to small temperature changes.

[0014] Compared to traditional processes, the main advantages of this invention are: First, it eliminates the need for specialized equipment and processes such as stretching, polarization, and bonding, resulting in shorter cycles, lower energy consumption, and easier mass production.

[0015] Second, the nanofibers are directly interwoven with the substrate, eliminating the need for adhesives, resulting in a strong interface and long lifespan.

[0016] Third, the high and uniform β-phase content results in sensitive sensing and stable signal. The addition of nano-graphene further enhances the pyroelectric sensitivity, enabling rapid response to even slight temperature changes.

[0017] Fourth, the microfiber leather base is soft, breathable, and has a good appearance and texture, and can be directly used in scenarios such as sofas, steering wheels, and robot skin to achieve invisible intelligent sensing. Detailed Implementation

[0018] The technical solution of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0019] This invention provides a one-step process for preparing pyroelectric intelligent sensing skin based on electrospinning technology, comprising the following steps: (1) Preparation of precursor solution: Dissolve pyroelectric material and highly conductive nano-dopant in a mixed solvent, stir evenly, let stand to remove bubbles, and obtain spinning solution.

[0020] (2) One-step electrospinning and polarization: The spinning solution is injected into the electrospinning device, and a flexible substrate is used as the receiving substrate. Electrospinning is carried out under the action of a high-voltage electrostatic field, so that the spinning solution is stretched and solidified into nanofibers while forming a high content of pyroelectric active β crystal phase in situ, which is directly deposited on the surface of the flexible substrate to form a nanofiber functional layer. In the nanofiber functional layer, the PVDF-TrFE / nano-doped composite nanofibers have a three-dimensional network porous structure. The three-dimensional porous structure gives the skin a high specific surface area and good air permeability, which is conducive to rapid heat transfer and temperature change response. At the same time, it improves the pyroelectric charge collection efficiency. The porous structure can also buffer mechanical deformation, enhance flexibility, and extend service life. The nanofiber functional layer forms a physical interweaving or mechanical interlocking bond with the flexible substrate at the interface through in-situ growth by electrospinning. This direct spinning allows the fibers to be embedded in the microstructure of the microfiber skin surface, forming a strong interface bond, avoiding the failure problem caused by adhesive aging or peeling in the traditional bonding process, and greatly improving the durability and signal stability of the skin.

[0021] (3) Preparation of electrode layer: An electrode layer is prepared on the surface of the nanofiber functional layer to extract electrical signals and obtain the pyroelectric smart sensing skin.

[0022] The core processes of the one-step fabrication process for the pyroelectric intelligent sensing skin of this invention include precursor solution preparation, in-situ electrospinning and polarization, and electrode layer preparation. First, the construction of the nanofiber network and the generation of the functional β-crystal phase are combined into one, eliminating the separate stretching, hot annealing, or high-pressure polarization post-treatment steps in traditional processes, significantly shortening the production cycle and reducing energy consumption and equipment costs. Second, the nanofibers are directly deposited on the surface of the flexible substrate, avoiding subsequent bonding processes and achieving integrated fusion of the functional layer and the substrate. Finally, through the action of a high-voltage electrostatic field, PVDF-TrFE is induced to form a high-content pyroelectric active β-crystal phase while the fibers are stretched and cured, ensuring that the skin has a sensitive and stable pyroelectric response.

[0023] Preferably, the pyroelectric material is a PVDF-TrFE copolymer. Compared with homopolymer PVDF, PVDF-TrFE copolymer has better crystallinity, which is conducive to the formation of the β-crystal phase, and a highly polar phase can be obtained without subsequent polarization.

[0024] Preferably, the highly conductive nano-dopant is one or more of graphene nanoparticles, carbon nanotubes, or conductive metal nanoparticles. The addition of highly conductive dopants such as graphene nanoparticles improves the electric field stretching efficiency during spinning, promoting the formation of the β-crystal phase; it also modulates the dielectric environment of the composite material, significantly increasing the pyroelectric coefficient and enhancing the sensitivity to minute temperature changes.

[0025] Preferably, the mixed solvent is composed of DMF and acetone in a volume ratio of 4:1. Acetone can evaporate rapidly, promoting rapid curing and shaping of the fibers, while DMF appropriately delays evaporation to ensure sufficient stretching of the jet, which is beneficial for the polymer chain arrangement to form a polar β-crystalline phase, thereby improving the purity and uniformity of the β-crystalline phase distribution.

[0026] In the spinning solution of step (1), the solid content of the pyroelectric material is 12%-18%, which can obtain a spinning solution with suitable viscosity, ensuring both continuous and stable jetting and the formation of nanofibers with uniform diameter. Below 12%, droplets are easily generated, while above 18%, spinning becomes difficult. The mass fraction of the highly conductive nano-dopant is 0.1-5% of the mass of the pyroelectric material. If it is too low, the modification effect is not obvious; if it is too high, it may lead to agglomeration, fiber defects, or destruction of the β-crystal phase. This range can improve the pyroelectric performance while maintaining the integrity of the fiber structure.

[0027] In step (2), the flexible substrate is microfiber skin. Microfiber skin has good flexibility, breathability and surface texture. It can be directly used as the outer layer of the final product and forms a physical interweaving with the nanofiber network. No adhesive is needed, thus avoiding interface delamination and signal attenuation.

[0028] The electrospinning process parameters are as follows: voltage 10-30 kV, receiving distance 10-20 cm, and spinning solution delivery rate 0.5-2 mL / h. A high-voltage DC electric field of 10-30 kV is applied between the spinneret and the receiving substrate in the electrospinning device, and the distance between the spinneret and the receiving substrate is 10-20 cm. The control of the voltage, distance, and delivery rate ensures the stable electrospinning process, uniform fiber diameter, and sufficient formation of the β-phase, while also ensuring the uniform deposition of nanofibers on the microfiber skin to form a three-dimensional porous network structure.

[0029] In step (3), the electrode layer is prepared by either magnetron sputtering or coating with conductive silver paste / silver nanowires. Magnetron sputtering is preferred as it yields a uniform, ultrathin electrode. Coating is more suitable for large-area or flexible devices, as it does not damage the underlying nanofiber structure and ensures effective signal extraction.

[0030] In this invention, the intelligent sensing skin comprises, from bottom to top: a flexible substrate, a PVDF-TrFE / nano-doped composite nanofiber functional layer grown in situ on the surface of the flexible substrate, and an electrode layer located on the surface of the functional layer.

[0031] In this invention, the intelligent sensing skin can be applied to pyroelectric sensors, smart homes, smart cockpits, wearable devices, and flexible sensing skins for robots.

[0032] The following examples and comparative examples illustrate the beneficial technical effects of the one-step preparation process of pyroelectric intelligent sensing skin based on electrospinning technology of the present invention. Example 1

[0033] This example provides a one-step fabrication process for pyroelectric intelligent sensing skin based on electrospinning technology, including the following steps: (1) 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.05g of nano-graphene (mass fraction 0.5%, Nanjing Xianfeng, average particle size <100nm) were added to 62.5mL of mixed solvent (the volume ratio of DMF and acetone is 4:1). The mixture was stirred at 40℃ for 4h until it was completely dissolved, and a uniform spinning solution with a solid content of 15% was obtained. The solution was then allowed to stand to remove bubbles.

[0034] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0035] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a nano-graphene-doped smart sensing skin. Example 2

[0036] This example provides a one-step fabrication process for pyroelectric intelligent sensing skin based on electrospinning technology, including the following steps: (1) Add 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.03g of multi-walled carbon nanotubes (Shenzhen Nanoport, outer diameter 10-20nm, length 10-30μm) to 62.5mL of mixed solvent (DMF and acetone volume ratio 4:1), stir at 40℃ for 4h until completely dissolved to obtain a uniform spinning solution with a solid content of 15%, and let stand to remove bubbles.

[0037] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0038] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a carbon nanotube-doped smart sensing skin. Example 3

[0039] This example provides a one-step fabrication process for pyroelectric intelligent sensing skin based on electrospinning technology, including the following steps: (1) 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.2g of nano-graphene (mass fraction 2%, Nanjing Xianfeng, average particle size <100nm) were added to 62.5mL of mixed solvent (the volume ratio of DMF and acetone is 4:1). The mixture was stirred at 40℃ for 4h until completely dissolved to obtain a uniform spinning solution with a solid content of 15%. The solution was then allowed to stand to remove bubbles.

[0040] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0041] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a highly doped smart sensing skin of nano-graphene.

[0042] Comparative Example 1 This example provides a manufacturing process for a smart sensor skin, including the following steps: (1) Add 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) to 62.5mL of mixed solvent (DMF and acetone volume ratio 4:1), stir at 40℃ for 4h until completely dissolved to obtain a transparent spinning solution, and let stand to remove bubbles.

[0043] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0044] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a nano-graphene-doped smart sensing skin.

[0045] Comparative Example 2 This example provides a manufacturing process for a smart sensor skin, including the following steps: (1) 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.05g of nano-graphene (mass fraction 0.5%, Nanjing Xianfeng, average particle size <100nm) were added to 62.5mL of DMF solvent and stirred at 40℃ for 4h until completely dissolved to obtain a uniform spinning solution with a solid content of 15% and allowed to stand to remove bubbles.

[0046] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0047] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a nano-graphene-doped smart sensing skin.

[0048] Comparative Example 3 This example provides a manufacturing process for a smart sensor skin, including the following steps: (1) Add 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.03g of multi-walled carbon nanotubes (Shenzhen Nanoport, outer diameter 10-20nm, length 10-30μm) to 62.5mL of mixed solvent (DMF and acetone volume ratio 4:1), stir at 40℃ for 4h until completely dissolved to obtain a uniform spinning solution with a solid content of 15%, and let stand to remove bubbles.

[0049] (2) A film was formed on a glass plate by solution casting, dried and peeled off to obtain a film with a thickness of about 30 μm; the film was placed in a high voltage polarization device and polarized for 30 min at 80℃ and 10 kV / mm.

[0050] (3) The polarized film is bonded to the microfiber skin with conductive adhesive, and then the electrode layer is sputtered by magnetron sputtering to obtain the traditional two-step skin.

[0051] Comparative Example 4 This example provides a smart sensing skin fabrication process, including the following steps: (1) Add 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.03g of multi-walled carbon nanotubes (Shenzhen Nanoport, outer diameter 10-20nm, length 10-30μm) to 62.5mL of mixed solvent (DMF and acetone volume ratio 4:1), stir at 40℃ for 4h until completely dissolved to obtain a uniform spinning solution with a solid content of 15%, and let stand to remove bubbles.

[0052] (2) After cleaning and drying, a regular PET film (0.1 mm thick) is flatly wrapped around the grounding roller receiver. The spinning solution is drawn into a 10 mL syringe, fitted with a 20 G stainless steel needle, and connected to the positive terminal of a high-voltage power supply. The voltage is set to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25 °C, and the relative humidity to 40%. Spinning is performed for 2 hours, forming a white nanofiber membrane (nanofiber functional layer) with a thickness of approximately 30 μm on the surface of the PET film.

[0053] (3) A thin gold electrode (about 50 nm thick) is deposited on the surface of the nanofiber membrane by magnetron sputtering, and copper wires are led out to obtain the PET substrate smart sensing skin.

[0054] Comparative Example 5 (1) Weigh 10g of homopolymer PVDF powder (Shanghai Sanaifu, molecular weight 400,000) and 0.05g of nanographene into 62.5mL of mixed solvent (DMF and acetone volume ratio 4:1), stir at 40℃ for 6h until completely dissolved to obtain a uniform spinning solution, and let stand to remove bubbles.

[0055] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0056] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a nano-graphene-doped smart sensing skin.

[0057] Comparative Example 6 This example provides a manufacturing process for a smart sensor skin, including the following steps: (1) 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.05g of nano-graphene (mass fraction 0.5%, Nanjing Xianfeng, average particle size <100nm) were added to 62.5mL of mixed solvent (the volume ratio of DMF and acetone is 4:1). The mixture was stirred at 40℃ for 4h until it was completely dissolved, and a uniform spinning solution with a solid content of 15% was obtained. The solution was then allowed to stand to remove bubbles.

[0058] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 5 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0059] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a nano-graphene-doped smart sensing skin.

[0060] Comparative Example 7 This example provides a manufacturing process for a smart sensor skin, including the following steps: (1) 10g of PVDF-TrFE copolymer powder (Arkema, molecular weight 450,000) and 0.05g of nano-graphene (mass fraction 0.5%, Nanjing Xianfeng, average particle size <100nm) were added to 126.7mL of mixed solvent (the volume ratio of DMF to acetone is 4:1). The mixture was stirred at 40℃ for 4h until completely dissolved to obtain a uniform spinning solution with a solid content of 8%. The solution was then allowed to stand to remove bubbles.

[0061] (2) Cut the microfiber skin (0.8 mm thick) into 20 cm × 20 cm pieces, clean them sequentially with ethanol and deionized water using ultrasonic cleaning, dry them at 60°C, and then flatten them onto the grounded roller receiver. Draw the spinning solution into a 10 mL syringe, install a 20 G stainless steel needle, and connect it to the positive terminal of a high-voltage power supply. Set the voltage to 20 kV, the receiving distance to 15 cm, the feed rate to 1 mL / h, the ambient temperature to 25°C, and the relative humidity to 40%. Spin for 2 hours to form a white nanofiber membrane (nanofiber functional layer) with a thickness of about 30 μm on the surface of the microfiber skin.

[0062] (3) A thin gold electrode was deposited on the surface of the nanofiber film using a magnetron sputtering instrument (sputtering current 20 mA, time 60 seconds, electrode thickness about 50 nm), and copper wires were attached with conductive silver paste to lead out the electrode, thus obtaining a nano-graphene-doped smart sensing skin.

[0063] The skin performance test items for the examples and comparative examples are as follows: β-phase content determination: Fourier transform infrared spectroscopy was used in the range of 400-4000 cm⁻¹. -1 Range scan.

[0064] Pyroelectric coefficient measurement: The skin sample (area 1 cm²) was placed on a temperature control stage and heated linearly at a rate of 1 °C / min. The short-circuit current I was recorded using an electrometer, and the pyroelectric coefficient was measured. Where A is the electrode area, dT / dt is the heating rate, and the average value is taken for each group of samples after 3 measurements.

[0065] Interfacial bond strength measurement: 90° peel test was performed in accordance with ASTM D6862 standard.

[0066] Response sensitivity measurement: Place the skin sample (area 1cm²) 5mm directly above the heat source (a copper block at a constant temperature of 50℃). After the temperature stabilizes, quickly remove the heat source and record the peak value of the open circuit voltage across the electrodes using an oscilloscope. The load resistance is 1GΩ. Take the average value of the peak values ​​for each group of measurements, which is 5 times.

[0067] Table 1 Performance data of the skins in the examples and comparative examples

[0068] in conclusion: 1. Comparison of Examples 1-3 with Comparative Example 1 (without dopant) shows that the addition of nano-graphene or carbon nanotubes can significantly increase the β-phase content and pyroelectric coefficient, and the response voltage also increases accordingly, indicating the promoting effect of dopant on β-phase formation and pyroelectric performance. However, excessive dopant content (Example 3) leads to a slight decrease in performance.

[0069] 2. The comparison between Example 1 and Comparative Example 2 (solvent without acetone) shows that the DMF / acetone mixed solvent (4:1) can obtain a higher β crystal phase content and pyroelectric coefficient than pure DMF, indicating that acetone volatilization regulates the fiber stretching and crystallization process and promotes the formation of polar phase.

[0070] 3. Compared with Comparative Example 3 (traditional two-step method), Example 1 has a higher β-phase content, better interface peeling strength, and higher response voltage, indicating that the one-step in-situ polarization is more efficient and the interface bonding is stronger.

[0071] 4. Compared with Comparative Example 4 (PET substrate), the microfiber skin substrate of Example 1 exhibits a much higher interfacial bonding strength than PET, indicating that the physical interweaving of the fiber and microfiber skin is the key; while the β phase content and pyroelectric coefficient are similar, indicating that the substrate type has little effect on the formation of internal crystal phases of the fiber.

[0072] 5. The β phase content and pyroelectric coefficient of Comparative Example 5 (homogeneous PVDF) are much lower than those of Example 1, indicating that the PVDF-TrFE copolymer is more conducive to the in-situ generation of the β phase and can obtain excellent pyroelectric performance without post-polarization.

[0073] 6. The comparison between Example 1 and Comparative Example 6 (5kV) shows that too low a voltage leads to insufficient fiber stretching, the β-phase content drops from 88.5% to 70.5%, and the pyroelectric coefficient and response voltage also decrease significantly. This indicates that a suitable voltage (10-30 kV) is the key to ensuring sufficient fiber polarization and good performance.

[0074] 7. Compared with Comparative Example 7 (8% solid content), when the solid content is too low, the viscosity of the spinning solution is insufficient, the jet is unstable, the fiber formation is poor, the β crystal phase content and the pyroelectric coefficient are significantly reduced, and the interfacial bonding strength is also reduced. This shows that the solid content range of 12-18% is crucial for obtaining high-quality nanofiber skin.

[0075] In summary, the pyroelectric smart sensing skin prepared by the one-step method of this invention is superior to the comparative example in terms of β phase content, pyroelectric coefficient, interfacial bonding strength, and response sensitivity, achieving the dual benefits of process simplification and performance improvement.

[0076] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A one-step preparation process for pyroelectric intelligent sensing skin based on electrospinning technology, characterized in that: Includes the following steps: (1) Preparation of precursor solution: Dissolve pyroelectric material and highly conductive nano-dopant in a mixed solvent, stir evenly, let stand to remove bubbles, and obtain spinning solution; (2) One-step electrospinning and polarization: The spinning solution is injected into the electrospinning device, and a flexible substrate is used as the receiving substrate. Electrospinning is carried out under the action of a high voltage electrostatic field, so that the spinning solution is stretched and solidified into nanofibers while forming a high content of pyroelectric active β crystal phase in situ, and directly deposited on the surface of the flexible substrate to form a nanofiber functional layer. (3) Preparation of electrode layer: An electrode layer is prepared on the surface of the nanofiber functional layer to extract electrical signals and obtain the pyroelectric smart sensing skin.

2. The one-step preparation process of pyroelectric intelligent sensing skin based on electrospinning technology according to claim 1, characterized in that: In step (1), the pyroelectric material is a PVDF-TrFE copolymer; the highly conductive nano-dopant is one or more of nano-graphene, carbon nanotubes or conductive metal nanoparticles; and the mixed solvent is composed of DMF and acetone in a volume ratio of 4:

1.

3. The one-step preparation process of pyroelectric intelligent sensing skin based on electrospinning technology according to claim 2, characterized in that: In the spinning solution described in step (1), the solid content of the pyroelectric material is 12%-18%; the mass fraction of the highly conductive nano-dopant is 0.1-5% of the mass of the pyroelectric material.

4. The one-step preparation process of pyroelectric intelligent sensing skin based on electrospinning technology according to claim 1, characterized in that: In step (2), the flexible substrate is microfiber skin; the electrospinning process parameters are: voltage 10-30kV, receiving distance 10-20cm, and spinning solution push rate 0.5-2mL / h.

5. The one-step preparation process of pyroelectric intelligent sensing skin based on electrospinning technology according to claim 1, characterized in that: In step (3), the electrode layer is prepared by either magnetron sputtering or coating with conductive silver paste / silver nanowires.

6. The one-step preparation process of pyroelectric intelligent sensing skin based on electrospinning technology according to claim 1, characterized in that: In the nanofiber functional layer, the PVDF-TrFE / nano-doped composite nanofibers have a three-dimensional network porous structure.

7. The one-step preparation process of pyroelectric intelligent sensing skin based on electrospinning technology according to claim 1, characterized in that: The nanofiber functional layer is physically interwoven or mechanically interlocked with the flexible substrate at the interface through in-situ electrospinning growth.

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