Triboelectricity nano-generator formed by spraying MXene on stretchable polyurethane fiber, preparation method and application of triboelectricity nano-generator

Abstract

The invention discloses a triboelectric nano-generator prepared by spraying MXene on stretchable polyurethane fibers, a preparation method and an application of the triboelectric nano-generator. The triboelectric nano-generator is integrally of a layered coaxial linear structure and comprises a stretchable layer, a conductive layer, a triboelectric layer and a two-dimensional material layer from inside to outside. The stretchable layer is a polyurethane (PU) layer; the conductive layer is formed by tightly winding a silver wire or a silver-coated nylon wire on the stretchable layer; the triboelectric layer is a polyamide (PA) layer and is used for generating a triboelectric effect; the two-dimensional material layer is used for improving the electrical output performance. According to the method, the production of the triboelectric nano generator FM-TENG with the stretchable polyurethane fiber sprayed with the MXene is realized through a two-step weaving process; the prepared triboelectric nano generator FM-TENG has excellent mechanical performance, stable electrical performance and high customizability, and can be widely applied to the fields of human motion recognition, energy collection, self-powered sensing and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of flexible electronic devices, and particularly to a triboelectric nanogenerator with stretchable polyurethane fibers sprayed with MXene, a preparation method thereof, and an application thereof. Background Art

[0002] With the rapid development of flexible electronic devices, wearable devices are increasingly widely used in fields such as human-computer interaction, medical monitoring, and energy harvesting. Traditional flexible sensors are usually based on mechanisms such as capacitance, piezoresistance, and piezoelectricity, but these sensors have limitations in terms of sensitivity, detection range, and stability. Triboelectric nanogenerators (TENGs), as an emerging energy harvesting and self-powered sensing technology, have the advantages of simple structure, strong adaptability, and the ability to work at low frequencies and small amplitudes, and are therefore considered an ideal choice for the next generation of wearable devices. However, most existing TENG devices have a planar structure and are difficult to adapt to irregular human movements. Due to the insufficient output performance of the nanogenerators, there are also challenges in production and customization. Fiber-structured TENGs (F-TENGs) have gradually become a research hotspot due to their shape adaptability, weavability, and breathability. However, existing F-TENGs have deficiencies in terms of conductivity and the stability of triboelectric materials, and it is difficult to achieve production and customized integration. Summary of the Invention

[0003] Aiming at the deficiencies of the above-mentioned existing technologies, the purpose of the present invention is to provide a triboelectric nanogenerator with stretchable polyurethane fibers sprayed with MXene (FM-TENG) suitable for production, a preparation method thereof, and an application thereof; the FM-TENG of the present invention has excellent mechanical properties, stable electrical properties, and high customizability, and can be applied to fields such as wearable devices, human motion recognition, energy harvesting, and self-powered sensing. The present invention uses a weaving technique to weave silver wires or nylon wires coated with silver into a conductive layer and wrap it around the outside of a polyurethane (PU) core layer. The conductive network formed by this weaving structure not only provides good conductivity but also has stability and reliability, ensuring the electrical performance stability of the F-TENG under complex deformations such as stretching, pressing, and twisting.

[0004] The technical solution of the present invention is specifically introduced as follows.

[0005] The present invention provides a triboelectric nanogenerator with stretchable polyurethane fibers sprayed with MXene. The triboelectric nanogenerator as a whole presents a layered coaxial structure, which from the inside to the outside includes a stretchable layer, a conductive layer, a triboelectric layer, and a two-dimensional material layer; wherein: The stretchable layer is a polyurethane PU layer, which is the core part of the triboelectric nanogenerator FM-TENG and is used to provide stretchable performance; The conductive layer is formed by tightly winding silver wires or nylon wires with a silver coating around the stretchable layer; The triboelectric layer is a polyamide PA layer, which is used to generate the triboelectric effect and is formed by tightly winding polyamide PA fibers around the outside of the conductive layer; The two-dimensional material layer is used to improve the electrical output performance and is formed by spraying a two-dimensional material solution on the triboelectric layer.

[0006] In the present invention, the conductive layer is formed on the stretchable layer through a weaving process, and the triboelectric layer is formed on the conductive layer through a weaving process.

[0007] In the present invention, the two-dimensional material layer is an MXene layer.

[0008] In the present invention, the diameter of the triboelectric nanogenerator is 1 ± 0.02 mm.

[0009] In the present invention, the working range of the triboelectric nanogenerator is 5 to 150 kPa, and the sensitivity is 0.0356 V / kPa -1 to 0.554 V / kPa -1 ; when its elongation is 0% to 60%, and after no less than 500 cycles under 0% to 50% strain, the elastic recovery rate still remains above 95%.

[0010] The present invention also provides a preparation method of the above-mentioned triboelectric nanogenerator, which is realized through two weaving processes and a spraying process; the specific steps are as follows: (1) Using polyurethane PU fibers as the core part, winding the polyurethane PU fibers around a fixed bobbin, and entering the weaving area through a tension device; through the weaving process, tightly winding silver wires or nylon wires with a silver coating wound on a spool around the polyurethane PU fibers to form a conductive layer, obtaining Ag / PU material; (2) Through the weaving process, winding the polyamide PA fibers wound on a spool around the Ag / PU material to form a triboelectric layer, obtaining a coaxial linear structure of PA / Ag / PU material; (3) Spraying the MXene supernatant on the PA / Ag / PU material to obtain a triboelectric nanogenerator with stretchable polyurethane fibers sprayed with MXene.

[0011] In the present invention, in step (3), the method for preparing the MXene supernatant is as follows: Lithium fluoride and hydrochloric acid are mixed and stirred, and then Ti3AlC2 is added thereto for an etching reaction. After the reaction is completed, the obtained solution is centrifuged, the supernatant is poured out, and centrifugation is continued until the pH of the supernatant poured out after centrifugation is 6. Ethanol is added to the centrifuge tube, and ultrasonic centrifugation is performed to obtain the MXene supernatant. In a specific embodiment, the concentration of the MXene supernatant is 6 wt% MXene, and it can be sprayed onto the prepared PA / Ag / PU material one or two times, and its dosage does not need to be strictly controlled. It is used to improve the electrical output performance of the generator.

[0012] Furthermore, the present invention provides an application of the above-mentioned triboelectric nanogenerator with stretchable polyurethane fiber sprayed with MXene in wearable devices.

[0013] Even further, the present invention provides an application of the triboelectric nanogenerator with stretchable polyurethane fiber sprayed with MXene in monitoring human motion signals. When applied, the triboelectric nanogenerator with stretchable polyurethane fiber sprayed with MXene is integrated into a wearable device through a weaving process to monitor human motion signals in real time. Preferably, the triboelectric nanogenerator with stretchable polyurethane fiber sprayed with MXene is integrated into socks through a weaving process, and the signals collected by the FM-TENG are classified based on a machine learning algorithm to achieve the recognition of five human actions: standing, slow walking, normal walking, running, and jumping.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows: High sensitivity and wide detection range: In the pressure range of 5 to 150 kPa, the sensitivity of the FM-TENG is 0.554 V / kPa.

[0015] Excellent mechanical properties: The FM-TENG has an elongation rate of up to 60%, and after no less than 500 cycles at 0% to 50% strain, the elastic recovery rate still remains above 95%.

[0016] Customizability and scalability: The FM-TENG can be woven into various textiles, such as wrist supports and socks, which can perfectly fit the human body to achieve the monitoring of motion signals.

[0017] Self-power supply and energy harvesting: The FM-TENG can convert mechanical energy into electrical energy to provide self-power supply capabilities for wearable devices.

[0018] Machine learning-assisted motion recognition: Based on the one-dimensional convolutional neural network 1D-CNN, the signals collected by the FM-TENG can be classified to accurately identify five human actions: standing, slow walking, normal walking, running, and jumping, and the recognition accuracy is as high as 99.02%. Brief Description of the Drawings

[0019] Figure 1 This is a schematic diagram of the manufacturing process of the present invention.

[0020] Figure 2 This is a schematic diagram of the weaving of the present invention.

[0021] Figure 3 This is a schematic diagram of the overall structure of the triboelectric nanogenerator of the present invention itself.

[0022] Figure 4 This is a schematic diagram of the manufacturing process in the embodiment of the present invention.

[0023] Figure 5 This is the electrical output performance diagram in Embodiment 1 of the present invention; (a) open-circuit voltage; (b) short-circuit current; (c) short-circuit charge transfer.

[0024] Figure 6 This is the sensing response diagram in Embodiment 1 of the present invention.

[0025] Figure 7 This is a schematic diagram of the structure of the intelligent sock of the present invention.

[0026] Figure 8 This is a schematic diagram of the physical object for application test of the present invention.

[0027] Reference numerals in the figure: 1, normally woven sock; 2, FM-TENG; 3, polyurethane PU layer; 4, bobbin; 5, silver wire; 6, weaving area; 7, polyamide PA layer; 8, MXene. Detailed Description of the Invention

[0028] As Figures 1-3 shown, the flexible polyurethane fiber sprayed with MXene triboelectric nanogenerator (FM-TENG) 2 of the present invention is overall linear (fibrous), and it adopts a layered coaxial structure, including a core polyurethane (PU) layer 3, an intermediate silver conductive layer 4, and an outer polyamide PA triboelectric layer 5. The production of FM-TENG is realized by spraying MXene 8 after a two-step weaving process. The two-step weaving process includes: The first step: the weaving of silver wire (or nylon wire coated with silver) wound around the polyurethane (PU) layer (fiber); this step forms a core-shell structure of Ag / PU. In this process, the PU fiber serves as the core, and through a specific weaving machine and process, the silver wire is tightly wound around the PU fiber to form a conductive layer. The second step: the weaving of polyamide (PA) fiber wound around the Ag / PU structure; this step further enhances the structural stability and triboelectric performance of the F-TENG. The PA fiber serves as the outer layer and is tightly wrapped around the Ag / PU structure through a weaving technique to form a complete coaxial structure (PA / Ag / PU).

[0029] The schematic diagram of the manufacturing process of the stretchable polyurethane fiber sprayed with MXene triboelectric nanogenerator in the embodiments of the present invention is as Figure 4 shown. The following are specific embodiments.

[0030] Example 1 Preparation of FM-TENG Step 1: Mix 2 g of lithium fluoride with 40 mL of hydrochloric acid and stir for 30 minutes, then add 2 g of Ti3AlC2 and stir at 35 °C for 24 hours. Centrifuge the above solution (3500 revolutions, 10 minutes), pour out the supernatant, take out and continue centrifuging until the pH of the supernatant poured out after centrifugation is 6. Add 40 mL of ethanol to the centrifuge tube and perform ultrasonic centrifugation to obtain the supernatant.

[0031] Step 2: Select polyurethane (PU) fiber as the core part, silver wire as the conductive layer, and polyamide (PA) fiber as the triboelectric layer. Wind the PU fiber around a fixed bobbin and feed it into the weaving area through a tension device. The bobbin in the weaving area is wound with silver wire to form the first layer of conductive layer (Ag / PU). Then, the PA fiber is wound around the Ag / PU layer to form the second layer of triboelectric layer (PA / Ag / PU). Spray the 6 wt% MXene supernatant on the second layer of triboelectric layer (PA / Ag / PU), and through the continuous operation of the weaving machine, the production of FM-TENG is realized.

[0032] Step 3: Use a yarn stretcher to test the elastic recovery rate of FM-TENG. The results show that after no less than 500 cycles at 50% strain, the elastic recovery rate is 95.12%.

[0033] Step 4: Use a linear motion motor to simulate various working modes, position control mode, speed control mode, force control mode, vibration simulation mode, etc., and measure the open-circuit voltage, short-circuit current, and short-circuit charge transfer of FM-TENG. As Figure 5 shown, the results show that FM-TENG exhibits a stable electrical output in the frequency range of 1 to 5 Hz.

[0034] Step 5: Take FM-TENG as a pressure sensor and test its voltage change under different pressures. As Figure 6 shown, the results show that FM-TENG works in the high-sensitive region below 30 kPa, with a sensitivity of 0.537 V / kPa -1 , and works in the low-sensitive region above 30 kPa, with a sensitivity of 0.0313 V / kPa -1 .

[0035] Step 6: Use a digital caliper (PD-301) to measure the diameter of the FM-TENG fiber to be 0.99 mm.

[0036] Example 2: Preparation of FM-TENG Step 1: The same as Step 1 of Example 1.

[0037] Step 2: The same as Step 2 of Example 2.

[0038] Step 3: Use a yarn tensile tester to test the elastic recovery rate of FM-TENG. The results show that after no less than 500 cycles under 25% strain, the elastic recovery rate remains at 97.05%.

[0039] Step 4: Use a linear motion motor to simulate various working modes, position control mode, speed control mode, force control mode, vibration simulation mode, etc., and measure the open-circuit voltage, short-circuit current, and short-circuit charge transfer of FM-TENG. The results show that FM-TENG exhibits a stable electrical output in the frequency range of 1 to 5 Hz.

[0040] Step 5: Take FM-TENG as a pressure sensor and test the voltage change under different pressures. The results show that FM-TENG works in the high-sensitivity region below 30 kPa, with a sensitivity of 0.541 V / kPa -1 , and works in the low-sensitivity region above 30 kPa, with a sensitivity of 0.0327 V / kPa -1 .

[0041] Step 6: Use a digital caliper (PD-301) to measure the diameter of the FM-TENG fiber to be approximately 1.00 mm, with a high linear sensing response.

[0042] Example 3: Preparation of FM-TENG Step 1: The same as Step 1 of Example 1.

[0043] Step 2: The same as Step 2 of Example 2.

[0044] Step 3: Use a yarn tensile tester to test the elastic recovery rate of FM-TENG. The results show that after no less than 500 cycles without strain, the elastic recovery rate remains at 99.01%.

[0045] Step 4: Use a linear motion motor to simulate various working modes, position control mode, speed control mode, force control mode, vibration simulation mode, etc., and measure the open-circuit voltage, short-circuit current, and short-circuit charge transfer of FM-TENG. The results show that FM-TENG exhibits a stable electrical output in the frequency range of 1 to 5 Hz.

[0046] Step 5: Take FM-TENG as a pressure sensor and test the voltage change under different pressures. The results show that FM-TENG works in the high-sensitivity region below 30 kPa, with a sensitivity of 0.554 V / kPa -1, operating in the low-sensitivity region above 30 kPa, with a sensitivity of 0.0356 V / kPa -1 .

[0047] Step Six: Use a digital caliper (PD-301) to measure the diameter of the FM-TENG fiber to be approximately 1.02 mm, with a high linear sensing response.

[0048] Example 4: Application of FM-TENG to smart socks The triboelectric nanogenerator (FM-TENG) with stretchable polyurethane fiber sprayed with MXene of the present invention as a whole presents a linear structure; this linear F-TENG can be integrated into various customized textiles through processes such as weaving, such as wrist supports and socks. These textiles can perfectly fit the human body and are used to monitor human motion signals. As Figure 7 and Figure 8 shown.

[0049] In the embodiment of the present invention, human motion signals are recognized based on smart socks; the socks are woven from FM-TENG fibers and are woven by traditional crochet methods, with good elasticity, breathability and fit. When a person moves, the FM-TENG device on the socks will come into contact with and separate from the skin or clothing, thereby generating electrical signals. These electrical signals are transmitted to the data acquisition system through wires and then recorded and analyzed. The signal data is stored in the form of a time series, and each time point corresponds to a voltage value. The data also contains metadata related to the movement, such as the type of action, timestamp, etc.

[0050] Data acquisition: The data is sourced from the human motion signals collected by the FM-TENG smart socks worn on the feet. Human motion actions include standing, slow walking, normal walking, running and jumping, etc.; First, the voltage output data obtained from the FM-TENG socks is divided at a certain time interval. Then, the voltage output data is divided at a certain time interval by extracting the characteristics of different waveforms through signal processing. Subsequently, the characteristics of different waveforms are extracted through signal processing, including the maximum value, minimum value, peak-to-peak value, etc.; Through repeated testing and verification, the features with the largest amount of information and the strongest discriminative ability are selected to form the final feature set; The dataset collected in the form of a time series signal is divided into a training set and a test set, with proportions of 70% and 30% respectively, for training and optimizing machine learning algorithms.

[0051] Feature Classification and Motion Recognition: The one-dimensional convolutional neural network (1D-CNN) method is used to effectively classify human motion patterns, and model optimization techniques are adopted to improve the performance of 1D-CNN. These techniques include hyperparameter tuning, systematically adjusting parameters such as the number of layers, the number of neurons in each layer, the learning rate, and the batch size to find the optimal configuration. At the same time, regularization techniques such as dropout and weight decay are applied to prevent overfitting and improve the robustness of the model. The preprocessed eigenvalue is used as the input learning sample and co-evolved to multiple pooling to complete the classification.

[0052] After 200 training epochs, the framework can obtain excellent classification accuracy and robustness. In addition, t-SNE visualization is used to transform the high-dimensional data output by the CNN into a low-dimensional space, and five actions (standing, slow walking, normal walking, running, and jumping) are displayed with a 99% confidence level, forming five clusters of different colors. The confusion matrix is used to prove the mismatch between the expected dataset and the test dataset. The results show that the accuracy of the corrected model is as high as 99.02%.

[0053] In summary, through the machine learning algorithm, based on the one-dimensional convolutional neural network 1D-CNN, the present invention can classify the signals collected by the FM-TENG through the training set and the test set. The FM-TENG can accurately identify five actions such as standing, slow walking, normal walking, running, and jumping, and the recognition accuracy is as high as 99.02%.

Claims

1. A triboelectric nanogenerator with stretchable polyurethane fiber sprayed with MXene, characterized in that, The triboelectric nanogenerator as a whole presents a hierarchical coaxial linear structure, which includes a stretchable layer, a conductive layer, a triboelectric layer, and a two-dimensional material layer from the inside to the outside; among which: The stretchable layer is a polyurethane (PU) layer, which is the core part of the triboelectric nanogenerator (FM-TENG) and is used to provide stretchable performance; The conductive layer is formed by tightly winding silver wires or nylon wires with silver coatings around the stretchable layer; The triboelectric layer is a polyamide (PA) layer, which is used to generate triboelectric effects and is formed by tightly winding polyamide (PA) fibers around the outside of the conductive layer; The two-dimensional material layer is used to improve the electrical output performance and is formed by spraying a two-dimensional material solution on the triboelectric layer.

2. The triboelectric nanogenerator according to claim 1, wherein The conductive layer is formed on the stretchable layer through a weaving process, and the triboelectric layer is formed on the conductive layer through a weaving process.

3. The triboelectric nanogenerator according to claim 1, wherein The two-dimensional material layer is a MXene layer.

4. The triboelectric nanogenerator according to claim 1, wherein The diameter of the triboelectric nanogenerator is 1 ± 0.02 mm.

5. The triboelectric nanogenerator according to claim 1, wherein The working range of the triboelectric nanogenerator is from 5 to 150 kPa, and the sensitivity is from 0.0356 V / kPa -1 to 0.554 V / kPa -1 ; its elongation rate ranges from 0% to 60%, and after no less than 500 cycles at 0% to 50% strain, the elastic recovery rate remains above 95%.

6. A method for preparing the triboelectric nanogenerator according to claim 1, characterized in that, The preparation of the triboelectric nanogenerator is realized through two weaving processes and a spraying process; the specific steps are as follows: (1) Using polyurethane (PU) fibers as the core part, winding the polyurethane (PU) fibers around a fixed bobbin and entering the weaving area through a tension device; through the weaving process, tightly winding the silver wires or nylon wires with silver coatings wound on the spool around the polyurethane (PU) fibers to form a conductive layer, and obtaining an Ag / PU material; (2) Through the weaving process, winding the polyamide (PA) fibers wound on the spool around the Ag / PU material to form a triboelectric layer, and obtaining a coaxial linear PA / Ag / PU material; (3) Spraying the MXene supernatant on the PA / Ag / PU material to obtain a triboelectric nanogenerator of stretchable polyurethane fibers sprayed with MXene.

7. The preparation method according to claim 6, characterized in that, In step (3), the preparation method of the MXene supernatant is as follows: After mixing and stirring lithium fluoride and hydrochloric acid, adding Ti3AlC2 thereto for an etching reaction, after the reaction ends, centrifuging the obtained solution, pouring out the supernatant, taking it out and continuing to centrifuge until the pH of the supernatant poured out after centrifugation is 6, adding ethanol to the centrifuge tube, and performing ultrasonic centrifugation to obtain the MXene supernatant.

8. Application of the triboelectric nanogenerator of stretchable polyurethane fibers sprayed with MXene according to any one of claims 1 to 5 in a wearable device.

9. Application of the stretchable polyurethane fiber sprayed with MXene according to any one of claims 1 to 5 in monitoring human motion signals, characterized in that, Integrating the triboelectric nanogenerator of stretchable polyurethane fibers sprayed with MXene into a wearable device through a weaving process to real-time monitor human motion signals.

10. The application according to claim 9, characterized in that, Integrating the triboelectric nanogenerator of stretchable polyurethane fibers sprayed with MXene into socks, classifying the signals collected by the FM-TENG based on a machine learning algorithm, and realizing the recognition of five human actions of standing, slow walking, normal walking, running, and jumping of the human body.

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