Flexible composite sensor based on nonwoven and tpu fibers and method of making the same

Abstract

The flexible composite sensor based on non-woven fabric and TPU fiber and a preparation method thereof include a pressure sensing unit and a temperature sensing unit, both of which share a TPU fiber pad as a dielectric layer substrate; the pressure sensing unit takes non-woven fabric as a substrate, and the non-woven fabric surface is adsorbed with reduced graphene oxide layer by layer to form a two-dimensional planar lapping type discontinuous conductive network; the reduced graphene oxide realizes sheet interlayer overlapping, edge interconnection and interlayer staggered arrangement at the fiber surface and gap of the non-woven fabric; under the action of van der Waals force, the two-dimensional planar lapping type discontinuous conductive network topologically reconfigures, evolves from a discontinuous two-dimensional planar overlapping structure into a three-dimensional through type dense conductive network connected with each other, and constitutes a pressure sensing sensitive layer; the pressure sensing sensitive layer is cut into a interdigital structure for an electrode layer of a capacitive pressure sensor; one side of the TPU fiber pad serves as a dielectric layer; and the other side is printed with PPC composite ink as a temperature sensing unit. The application realizes accurate and stable detection of pressure and temperature signals.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensor technology, specifically relating to a flexible composite sensor based on nonwoven fabric and TPU fiber and its preparation method. Background Technology

[0002] Flexible sensors, as core sensing components for human-computer interaction, physiological monitoring, and smart wearable devices, have shown broad application prospects in emerging fields such as human physiological signal monitoring, smart healthcare, and flexible electronics due to their excellent flexibility, fit, portability, and large-area fabrication capabilities. Pressure sensors and temperature sensors are the two most widely used and urgently needed core sensing units for human applications; their sensing performance directly determines the detection accuracy, reliability, and practical application value of the entire monitoring system.

[0003] Currently, pressure sensors primarily use conductive materials such as graphene and carbon nanotubes as the sensitive layer material. However, existing fabrication processes suffer from problems such as uneven conductive network distribution, low sensor sensitivity, and poor structural stability. A flexible pressure sensor and its fabrication method, disclosed in CN108195491A, uses a blend of carbon nanotubes and polydimethylsiloxane (PDMS) as the piezoresistive sensitive layer. However, carbon nanotubes are prone to aggregation and sedimentation due to their high surface energy and van der Waals forces, resulting in uneven conductive network distribution. Temperature sensors are mostly fabricated using coating and vapor deposition processes, which suffer from complex processes, high costs, weak bonding with flexible substrates, and difficulty in large-scale fabrication. Some thermosensitive materials also exhibit poor compatibility, making stable bonding with flexible substrates difficult. A thermosensitive thin film and its wire fabrication method, disclosed in CN104760919A, uses a metal oxide thermosensitive material combined with a polyimide (PI) flexible substrate. Due to the significant difference in thermal expansion coefficients between inorganic thermosensitive materials and organic polymer substrates, the interfacial stress matching is poor, making long-term stable interfacial bonding with flexible substrates difficult.

[0004] Therefore, developing a flexible sensing material that is fully flexible, low-cost, stable in performance, and capable of simultaneously achieving accurate pressure and temperature detection has become a pressing technical challenge in the field of flexible sensors. Summary of the Invention

[0005] In order to overcome the shortcomings of the existing technology, the present invention aims to provide a flexible composite sensor based on nonwoven fabric and TPU fiber and its preparation method, which solves the problems of low sensitivity of existing pressure sensors, complex preparation process of temperature sensors, and weak bonding with flexible substrates, and realizes accurate and stable detection of pressure and temperature signals.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A flexible composite sensor based on nonwoven fabric and TPU (thermoplastic polyurethane elastomer) fiber includes a pressure sensing unit and a temperature sensing unit. Both share a TPU fiber pad as the dielectric layer substrate, forming a composite structure with independent signals (Janus characteristics), enabling the composite sensor to have both pressure and temperature responses. The specific structure is as follows: The electrodes of the pressure sensing unit are based on non-woven fabric as a framework. The non-woven fabric is adsorbed, dried, ultrasonically cleaned, and dried in reduced graphene oxide (rGO) slurry, thereby forming a two-dimensional planar overlapping discontinuous conductive network layer by layer. As the number of rGO adsorption layers increases, the bonding between rGO and the fibers of the non-woven fabric becomes more and more uniform and tight. Thanks to the three-dimensional spatial constraint effect of the porous non-woven fabric framework, the rGO nanosheets achieve interlayer overlap, edge interconnection, and interlayer staggered arrangement on the fiber surface and in the gaps. Under the influence of van der Waals forces, the two-dimensional planar overlapping discontinuous conductive network undergoes topological reconstruction, evolving from a discontinuous two-dimensional planar overlapping structure into an interconnected three-dimensional through-type dense conductive network. Finally, non-woven fabric is cut into interdigitated electrode shapes and placed on one side of TPU fiber (dielectric layer) to form a capacitive pressure sensing layer; this interdigitated structure is used as the electrode layer for capacitive pressure sensors. One side of the TPU fiber pad serves as the dielectric layer; Using a TPU fiber pad as a substrate, PPC composite ink is directly printed on the other side of the TPU fiber pad to serve as a temperature sensing unit. Both share the TPU fiber pad, resulting in a composite structure but independent signals.

[0007] The natural micro-roughness and interfacial active sites on the surface of the TPU fibers provide ample space for the wetting, penetration, and interfacial bonding of the composite ink. Driven by capillary forces, the PPC composite ink spontaneously penetrates into the internal pores and interfiber gaps of the TPU fiber pad to form a continuous and interconnected conductive and thermosensitive pathway, ultimately forming a temperature-sensitive layer. The surface of the temperature-sensitive layer exhibits a corrugated micromorphology with uneven textures along with the underlying fiber network, fully preserving the porous structure and flexible deformation capability of the fiber substrate.

[0008] The nonwoven fabric is a conventional flexible nonwoven fabric, preferably a cellulose nonwoven fabric, with a thickness of 0.1-0.3 mm and a porosity of 50%-80%. The number of rGO adsorption layers is 1-6, preferably 5.

[0009] The dielectric layer is a fiber pad obtained by electrospinning TPU, with a thickness of 0.2-0.5 mm.

[0010] The PPC composite ink is composed of PVA (polyvinyl alcohol), PEDOT:PSS (poly(3,4-ethylenedioxythiophene)-poly(styrene sulfonate)) and CNTs (carbon nanotubes) in a mass ratio of (3-4):(8-10):(1-2).

[0011] The viscosity of the PPC composite ink is 1200-1500 mPa·s, and the shear rate is 500-1000 s. -1 It combines excellent formability and printability, making it fully compatible with the large-area direct-write fabrication process for flexible electronics.

[0012] The method for fabricating the above-mentioned flexible composite sensor includes the following steps: Step 1): Fabrication of TPU fiber pads and interdigitated electrode structures; Step 2): Fabricate the temperature sensing unit; Step 3): Fabrication of the composite sensor: To reduce the thickness of the composite sensor, interdigitated electrodes are laid flat on one side of the same TPU fiber pad to obtain a pressure sensor, and PPC ink is printed on the other side to prepare a temperature sensor. The pressure sensor and the temperature sensor are then encapsulated together to obtain a fully flexible composite sensor.

[0013] Step 1) specifically refers to: 1.1) Pre-treatment of non-woven fabric: Cut the non-woven fabric to the preset size, and ultrasonically clean it with deionized water and anhydrous ethanol for 10-15 minutes in sequence to remove surface impurities and oil stains. Then place it in a 60℃ oven to dry for later use. 1.2) Layer-by-layer adsorption of rGO: The pretreated nonwoven fabric is immersed in rGO slurry and adsorbed using the dip-pull method for 10-20 min. Then it is placed in a 60℃ oven to dry, completing the adsorption of 1 layer of rGO. The above dip-pull-drying steps are repeated until 1-6 layers of rGO are adsorbed, and a nonwoven fabric substrate with adsorbed rGO is obtained. 1.3) Cutting interdigitated electrodes: Flatten the prepared nonwoven fabric substrate and laser cut it into interdigitated electrode structures for later use.

[0014] 1.4) Preparation of dielectric layer: Place TPU solution in an electrospinning machine, collect TPU fibers on a flat plate to obtain TPU fiber pad; cut the TPU fiber pad to a preset size for later use.

[0015] Preferably, the drying time in steps 1.1) and 1.2) is not fixed, and the drying continues until the nonwoven fabric is completely dry.

[0016] Preferably, the interdigitated electrode structure in step 1.3) means that its length and width remain unchanged, the number of teeth is 0-5, preferably 4, the overall length is 3-4cm, and the width is 2-2.5cm.

[0017] Preferably, in step 1.4), the TPU solution is obtained by dissolving TPU particles in a mixed solution of THF and DMF and stirring for 24 hours to obtain a 10-20 wt% TPU electrospinning solution.

[0018] Step 2) specifically refers to: 2.1) Preparation of PPC composite ink: Weigh PVA, PEDOT:PSS and CNTs in a mass ratio of (3-4):(8-10):(1-2). First, add PVA to deionized water and heat to 80°C and stir to dissolve. After cooling to room temperature, add PEDOT:PSS and CNTs and stir to obtain a uniform and stable PPC composite ink. 2.2) Ink printing: Fix the TPU fiber pad on the printing platform, select the appropriate printer ink cartridge tip (tip diameter is 0.1-0.3mm), load the PPC composite ink into the printer ink cartridge, set the printing parameters: printing speed is 5-10mm / s, printing temperature is room temperature, and perform direct writing printing according to the preset temperature sensor trapezoidal pattern. 2.3) Curing and molding: The printed TPU fiber pad is placed in an oven to dry, so that the PPC composite ink is cured into a film, forming a stable temperature sensing layer, which is the temperature sensing unit.

[0019] The beneficial effects of this invention are: 1. The pressure sensing unit of this invention adopts a non-woven fabric layer-by-layer adsorption of rGO preparation process, which makes the conductive network evolve from a two-dimensional discontinuous type to a three-dimensional through-dense type, effectively shortening the carrier transport path, reducing the interface transport barrier, and significantly improving the sensitivity and structural stability of the pressure sensor. At the same time, the non-woven fabric substrate has the characteristics of low cost, good air permeability and excellent flexibility, which is suitable for large-area application scenarios of flexible sensing. 2. The temperature sensing unit of this invention is prepared by printing PPC composite ink on TPU fiber pad. The ink formula is reasonable, with suitable viscosity and fluidity, and it is firmly bonded to the TPU fiber substrate and is not easy to fall off. Moreover, the printing process is simple and can achieve high-precision pattern printing, which is suitable for large-scale integrated preparation. 3. The pressure sensing unit and temperature sensing unit of this invention provide independent signals, but share a dielectric layer, reducing the overall thickness. The fabrication process is compatible, enabling accurate detection of pressure and temperature signals separately. Furthermore, the overall fabrication cost is low, and the air permeability is high, requiring no complex equipment. This solves the problems of complex fabrication processes, unstable performance, and high cost associated with existing flexible sensors, and has broad application prospects. 4. The PPC composite ink-based temperature sensor operates based on the negative temperature coefficient (NTC) thermistor mechanism, exhibiting sensitive and stable temperature response. The nonwoven pressure sensor adsorbing rGO has high sensitivity and strong mechanical durability, meeting the application requirements of scenarios such as human physiological monitoring. Attached Figure Description

[0020] Figure 1 The conductivity of the nonwoven fabric prepared in this invention adsorbing 1-5 layers of rGO.

[0021] Figure 2 The image shows the SEM morphology of the nonwoven fabric with 5 layers of adsorbed rGO prepared in Example 1 of this invention.

[0022] Figure 3 The water contact angle of the surface of the nonwoven fabric with 5 layers of adsorbed rGO prepared in Example 1 of the present invention.

[0023] Figure 4 The 12-hour air permeability of the nonwoven fabric and TPU fiber pad with 5 layers of adsorbed rGO prepared in Example 1 of the present invention and the control group.

[0024] Figure 5 The sensitivity curve of the pressure sensor prepared in Example 1 of the present invention.

[0025] Figure 6 The response recovery time is the pressure sensor prepared in Embodiment 1 of the present invention.

[0026] Figure 7 Sensitivity curve of the temperature sensor prepared for this invention.

[0027] Figure 8 Viscosity test of the PPC ink prepared in this invention is shown in the illustration, which is a PPC ink.

[0028] Figure 9 The conductivity of the nonwoven fabric prepared in Example 2 of this invention with 1-5 layers of rGO brush coating.

[0029] Figure 10 Left: Pressure sensor; Right: Temperature sensor prepared according to Embodiment 1 of the present invention. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings.

[0031] Example 1 The flexible composite sensor based on nonwoven fabric and TPU fiber and its fabrication method are as follows: Step 1): Fabrication of the pressure sensing unit: 1.1) Pre-treatment of non-woven fabric: Cut the non-woven fabric to the preset size, and ultrasonically clean it with deionized water and anhydrous ethanol for 15 minutes in sequence to remove surface impurities and oil stains. Then place it in a 60℃ oven to dry for later use. 1.2) Layer-by-layer adsorption of rGO: The pretreated nonwoven fabric is immersed in rGO slurry and adsorbed using the dip-pull method for 15 minutes. Then it is placed in a 60℃ oven to dry, completing the adsorption of 1 layer of rGO. The above dip-pull-drying steps are repeated until 5 layers of rGO are adsorbed, and a nonwoven fabric substrate with adsorbed rGO is obtained. 1.3) Cutting the interdigitated electrode: Flatten the prepared nonwoven fabric substrate and laser cut it into a 4-tooth interdigitated electrode structure with an overall length of 3cm and a width of 2cm, for later use.

[0032] 1.4) Preparation of dielectric layer: TPU particles (2g), THF (5mL), and DMF (5mL) were mixed and stirred evenly to obtain a TPU solution. Electrospinning was then performed, and the TPU fibers were collected on a flat plate to obtain a TPU fiber pad. The TPU fiber pad was then cut to a predetermined size for later use.

[0033] Step 2): Fabrication of the temperature sensing unit: 2.1) Preparation of PPC composite ink: Weigh PVA (0.3g), PEDOT:PSS (10mL), and CNTs (0.2g). First, add PVA to deionized water and heat to 80℃ while stirring to dissolve. After cooling to room temperature, add PEDOT:PSS and CNTs, and stir to obtain a uniform and stable PPC composite ink. 2.2) Ink printing: Fix the TPU fiber pad on the printing platform, select the appropriate printer ink cartridge tip (tip diameter is 0.26mm), load the PPC composite ink into the printer ink cartridge, set the printing parameters: printing speed is 8mm / s, printing temperature is room temperature, and perform direct writing printing according to the preset temperature sensing pattern. 2.3) Curing and molding: The printed TPU fiber pad is placed in a 30℃ oven to dry, so that the PPC composite ink is cured into a film, forming a stable temperature sensing layer, which is the temperature sensing unit.

[0034] Step 3): Fabrication of the composite sensor: The 4-tooth interdigital electrode prepared in step 1.3) is placed flat on the other side of the TPU fiber pad containing the temperature sensing module printed in step 2.3). The entire assembly is then encapsulated to obtain a fully flexible composite sensor.

[0035] Measurements showed that the composite sensor prepared in this embodiment has a conductivity as high as 155.45 S / m ( Figure 1 ).

[0036] The pressure sensing unit, when five layers of rGO are adsorbed onto the nonwoven fabric, exhibits a more uniform and tighter bonding between graphene and fiber, and reaches saturation. Figure 2 ).

[0037] With the addition of rGO, the static water contact angle of the nonwoven substrate gradually increased to 34.9°, indicating that its overall wettability changed from hydrophilic to hydrophobic. Figure 3 ).in addition, Figure 4 The air permeability of the nonwoven electrode and the dielectric layer TPU fiber in the middle is similar to that of the blank group, indicating that it has excellent air permeability. Figure 5 The pressure sensor fabricated using TPU fibers exhibits a sensitivity of 1.47 kPa within a pressure range of 0-3 kPa. -1 It reaches 0.03 kPa in the range of 3-35 kPa. -1 The response time and recovery time reached 121ms and 189ms, respectively. Figure 6 The temperature sensing unit exhibits a stable temperature response within the 10-60℃ range, with a sensitivity as high as [missing value] in the low-temperature region (10-25℃). 4.7% °C -1 ( Figure 7 ). Figure 8 The rheological curves in the figure show that PPC ink exhibits typical shear thinning behavior, ensuring good storage stability, flowability and coating performance. The illustrations also show the ink's uniformity and flowability, as well as its excellent formability and printability.

[0038] Example 2 The flexible composite sensor based on nonwoven fabric and TPU fiber and its fabrication method are as follows: Step 1): Fabrication of the pressure sensing unit: 1.1) Pre-treatment of non-woven fabric: Cut the non-woven fabric to the preset size, and ultrasonically clean it with deionized water and anhydrous ethanol for 15 minutes in sequence to remove surface impurities and oil stains. Then place it in a 60℃ oven to dry for later use. 1.2) Layer-by-layer rGO coating: The pretreated nonwoven fabric is laid flat, and rGO is brushed onto the nonwoven fabric using a brush coating method. Then it is placed in a 60℃ oven to dry, completing the adsorption of 1 layer of rGO. Repeat the above brush coating-drying steps until 5 layers of rGO are brushed onto the nonwoven fabric to obtain a nonwoven fabric substrate coated with rGO. 1.3) Cutting the interdigitated electrode: Flatten the prepared nonwoven fabric substrate and laser cut it into a 4-tooth interdigitated electrode structure with an overall length of 3cm and a width of 2cm, for later use.

[0039] 1.4) Preparation of dielectric layer: TPU particles (2g), THF (5mL), and DMF (5mL) were mixed and stirred evenly to obtain a TPU solution. Electrospinning was then performed, and the TPU fibers were collected on a flat plate to obtain a TPU fiber pad. The TPU fiber pad was then cut to a predetermined size for later use.

[0040] Step 2): Fabrication of the temperature sensing unit: 2.1) Preparation of PPC composite ink: Weigh PVA (0.3g), PEDOT:PSS (10mL), and CNTs (0.2g). First, add PVA to deionized water and heat to 80℃ while stirring to dissolve. After cooling to room temperature, add PEDOT:PSS and CNTs, and stir to obtain a uniform and stable PPC composite ink. 2.2) Ink printing: Fix the TPU fiber pad on the printing platform, select the appropriate printer ink cartridge tip (tip diameter is 0.26mm), load the PPC composite ink into the printer ink cartridge, set the printing parameters: printing speed is 8mm / s, printing temperature is room temperature, and perform direct writing printing according to the preset temperature sensing pattern. 2.3) Curing and molding: The printed TPU fiber pad is placed in a 30℃ oven to dry, so that the PPC composite ink is cured into a film, forming a stable temperature sensing layer, which is the temperature sensing unit.

[0041] Step 3): Fabrication of the composite sensor: The 4-tooth interdigital electrode prepared in step 1.3) is placed flat on the other side of the TPU fiber pad containing the temperature sensing module printed in step 2.3). The entire assembly is then encapsulated to obtain a fully flexible composite sensor.

[0042] Similarly, the functional characteristics were evaluated, and the conductivity of the interdigitated electrode prepared in this embodiment was significantly lower than that in Example 1. Figure 9 The adsorption method enables rGO to form a uniform coating on the fiber surface and fill the pores, shortening the carrier transport path and reducing the interfacial energy barrier. After five immersion cycles, a strong interfacial anchoring structure is formed between rGO and the fiber matrix, creating a stable three-dimensional conductive network with almost consistent resistance before and after cleaning. In contrast, the brush coating method forms localized two-dimensional conductive pathways on the nonwoven fabric surface as the coating thickness increases. These pathways are easily detached after ultrasonic cleaning and tend to cause particle aggregation and uneven fiber coverage. This method cannot construct a stable three-dimensional conductive framework, and its conductivity is far inferior to that of the adsorption method.

[0043] In summary, the composite sensor prepared by this invention possesses excellent flexibility and breathability. The pressure sensing unit and temperature sensing unit are tightly integrated without interfering with each other, such as... Figure 10The left side shows one pressure sensing unit, and the right side shows the other temperature sensing unit. This invention features a simple manufacturing process, low cost, good stability, and is suitable for large-area fabrication, facilitating mass production.

Claims

1. A flexible composite sensor based on nonwoven fabric and TPU fiber, characterized in that, It includes a pressure sensing unit and a temperature sensing unit, both of which share a TPU fiber pad as the dielectric layer substrate, forming a composite structure while maintaining independent signals. The pressure sensing unit uses non-woven fabric as a substrate, and the surface of the non-woven fabric is adsorbed and reduced layer by layer to form a two-dimensional planar overlapping discontinuous conductive network. Reduced graphene oxide achieved interlayer overlap, edge interconnection, and interlayer staggered arrangement on the fiber surface and gaps of nonwoven fabrics; Under the action of van der Waals forces, the two-dimensional planar overlapping discontinuous conductive network undergoes topological reconstruction, evolving from a discontinuous two-dimensional planar overlapping structure into an interconnected three-dimensional through-type dense conductive network, forming a pressure sensing layer. It was cut into an interdigitated structure for use as the electrode layer in a capacitive pressure sensor; One side of the TPU fiber pad serves as the dielectric layer; using the TPU fiber pad as a substrate, PPC composite ink is printed on the other side of the TPU fiber pad to serve as a temperature sensing unit.

2. The flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 1, characterized in that, The PPC composite ink spontaneously penetrates into the internal pores and fiber gaps of the TPU fiber pad to form a continuous and interconnected conductive and thermosensitive pathway, forming a temperature-sensitive layer; the surface of the temperature-sensitive layer exhibits an uneven, wavy micromorphology along with the underlying fiber network.

3. The flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 1, characterized in that, The nonwoven fabric is a conventional flexible nonwoven fabric with a thickness of 0.1-0.3 mm and a porosity of 50%-80%. The number of rGO adsorption layers is 1-6.

4. The flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 1, characterized in that, The dielectric layer is a fiber pad obtained by electrospinning TPU, with a thickness of 0.2-0.5 mm.

5. The flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 1, characterized in that, The PPC composite ink is composed of PVA, PEDOT:PSS and CNTs, with a mass ratio of (3-4):(8-10):(1-2).

6. The flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 1, characterized in that, The viscosity of the PPC composite ink is 1200-1500 mPa·s, and the shear rate is 500-1000 s. -1 .

7. A method for fabricating a flexible composite sensor based on nonwoven fabric and TPU fiber according to any one of claims 1-6, characterized in that, Includes the following steps: Step 1): Fabrication of TPU fiber pads and interdigitated electrode structures; Step 2): Fabricate the temperature sensing unit; Step 3): Assemble interdigitated electrodes on one side of the same TPU fiber pad to obtain a pressure sensor, and set a temperature sensing unit on the other side. Encapsulate the pressure sensor and temperature sensor together to obtain a fully flexible composite sensor.

8. The method for fabricating a flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 7, characterized in that, Step 1) specifically refers to: 1.1) Cut the non-woven fabric to the preset size, and ultrasonically clean it with deionized water and anhydrous ethanol for 10-15 minutes in sequence to remove surface impurities and oil stains. Then place it in a 60℃ oven to dry for later use. 1.2) The pretreated nonwoven fabric is immersed in rGO slurry and adsorbed using the immersion-lifting method for 10-20 min. Then it is placed in a 60℃ oven to dry, completing the adsorption of 1 layer of rGO. The above immersion-lifting-drying steps are repeated until 1-6 layers of rGO are adsorbed layer by layer, and a nonwoven fabric substrate with adsorbed rGO is obtained. 1.3) Flatten the prepared nonwoven fabric substrate and laser-cut it into interdigitated electrode structures for later use; 1.4) Place the TPU solution in an electrospinning machine and collect the TPU fibers on a flat plate to obtain a TPU fiber pad; cut the TPU fiber pad to a preset size for later use.

9. The method for fabricating a flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 8, characterized in that, The interdigitated electrode structure in step 1.3) refers to an electrode with a constant length and width, 0-5 teeth, an overall length of 3-4 cm, and a width of 2-2.5 cm. In step 1.4), the TPU solution is obtained by dissolving TPU particles in a mixed solution of THF and DMF and stirring for 24 hours to obtain a 10-20 wt% TPU electrospinning solution.

10. The method for fabricating a flexible composite sensor based on nonwoven fabric and TPU fiber according to claim 7, characterized in that, Step 2) specifically refers to: 2.1) Weigh PVA, PEDOT:PSS and CNTs according to the mass ratio (3-4): (8-10): (1-2). First, add PVA to deionized water and heat to 80°C and stir to dissolve. After cooling to room temperature, add PEDOT:PSS and CNTs and stir to obtain a uniform and stable PPC composite ink. 2.2) Fix the TPU fiber pad on the printing platform, select the appropriate printer ink cartridge needle, load the PPC composite ink into the printer ink cartridge, set the printing parameters: printing speed is 5-10mm / s, printing temperature is room temperature, and perform direct writing printing according to the preset temperature sensing trapezoidal pattern. 2.3) Place the printed TPU fiber pad in an oven to dry, so that the PPC composite ink can be cured into a film, forming a stable temperature sensing layer, thus obtaining the temperature sensing unit.

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