Flexible tensile sensor, fabrication method and facial information sensing system

Abstract

This invention relates to a flexible tensile sensor, its preparation method, and a facial information sensing system. The preparation method of the flexible tensile sensor includes the following steps: preparing a spinning solution; preparing a styrene-butadiene-styrene block copolymer film, i.e., an SBS nanofiber membrane, using an electrospinning process; and hydrophilically treating the SBS nanofiber membrane; immersing the hydrophilically treated SBS nanofiber membrane in single-walled carbon nanotube solutions of different concentrations and subjecting it to ultrasonic treatment to obtain a styrene-butadiene-styrene block copolymer / single-walled carbon nanotube fiber membrane, i.e., an SBS / CNT fiber membrane; attaching adhesive tape as a separator layer to both the upper and lower surfaces of the obtained SBS / CNT fiber membrane; screen-printing conductive silicone onto the separator layer on the upper surface; and finally cutting the membrane to obtain the flexible tensile sensor.

Description

Technical Field

[0001] This invention relates to the field of tensile sensor technology, specifically to a flexible tensile sensor, its preparation method, and a facial information sensing system. Background Technology

[0002] The statements in this section are merely background information related to the present invention and do not necessarily constitute prior art.

[0003] Flexible tensile sensors can convert strain signals from sensors into electrical signals, enabling the detection of tensile deformation and giving them a function similar to that of human skin in sensing deformation.

[0004] Current flexible resistive tensile sensors typically suffer from drawbacks such as unstable initial resistance, low sensitivity, and small response range. Their fabrication process is complex, the required materials are expensive, and the technology is costly. Furthermore, most current flexible resistive tensile sensors can only measure a single strain signal and cannot sense multiple signals like human skin.

[0005] Electronic skin can adapt to changes in human movement and has a good rate of change in electrical resistance. However, most flexible resistive stretch sensors are currently thick, making it difficult to maintain a close fit to the skin while ensuring wearing comfort. For wearable electronic devices that are in direct contact with the human body, in addition to excellent electronic properties, safety is also a crucial factor to consider. Due to the influence of materials, biocompatibility and safety are limited, and prolonged wear may lead to a series of skin problems such as skin allergies.

[0006] In addition, most flexible stretch sensors are currently only used for simple detection of physiological signals, relying on large equipment for signal post-processing. They usually require computers and other equipment to achieve the required functions, which is inconvenient to carry and limits the application scenarios of the sensors. Summary of the Invention

[0007] To address the technical problems mentioned above, this invention provides a flexible stretch sensor, a fabrication method, and a facial information sensing system. These sensors exhibit high sensitivity, low hysteresis, and good repeatability, and can be widely applied in electronic skin, wearable products, implantable devices, and multifunctional sensor systems. Furthermore, this invention presents a facial information sensing system based on an FPGA platform, which is portable and does not require a computer or other equipment, thus broadening the application scenarios of the flexible stretch sensor.

[0008] To achieve the above objectives, the present invention adopts the following technical solution:

[0009] The first aspect of the present invention provides a method for fabricating a flexible tensile sensor, comprising the following steps:

[0010] A spinning solution was prepared, and a styrene-butadiene-styrene block copolymer film, namely SBS nanofiber membrane, was prepared by electrospinning process. The SBS nanofiber membrane was then hydrophilically treated.

[0011] The hydrophilically treated SBS nanofiber membrane was immersed in single-walled carbon nanotube solutions of different concentrations and then subjected to ultrasonic treatment to obtain a styrene-butadiene-styrene block copolymer / single-walled carbon nanotube fiber membrane, namely SBS / CNT fiber membrane.

[0012] Stickers and tapes were pasted on the upper and lower surfaces of the prepared SBS / CNT fiber membrane as separators, and conductive silicone was screen-printed onto the separators on the upper surface. After cutting, a flexible tensile sensor was obtained.

[0013] The preparation process of conductive silicone is as follows: carbon black is added to a solvent, stirred and ultrasonically treated, then silicone rubber is added, and the mixture is stirred and ultrasonically treated again to obtain conductive silicone; by controlling different contents of carbon black, conductive silicone with different initial resistances is obtained.

[0014] The spinning solution is prepared by dissolving granular styrene-butadiene-styrene block copolymer in a solvent to obtain a solution with a concentration of 7-10 wt%, and stirring to obtain a homogenized spinning solution.

[0015] Solvents include any one or a mixture of several of the following: N,N-dimethylformamide, tetrahydrofuran, n-hexane, and alcohol.

[0016] The SBS nanofiber membrane undergoes hydrophilic treatment specifically as follows: polydopamine is dissolved in an alkaline buffer solution and ultrasonically treated. The SBS nanofiber membrane is then immersed in the ultrasonically treated polydopamine solution for a set time, removed, and dried to complete the hydrophilic treatment.

[0017] The SBS nanofiber membrane was prepared by electrospinning at a speed of 5-8 ml / h, a voltage of 16-24 kV, a receiving distance of 12-18 cm, and a spinning duration of 4-12 h.

[0018] The SBS / CNT fiber membrane was obtained as follows:

[0019] (a) Dilute the single-walled carbon nanotube solution to obtain a single-walled carbon nanotube solution of the desired concentration;

[0020] (b) Immerse the hydrophilically treated SBS nanofiber membrane in a carbon nanotube solution of the required concentration for a set time.

[0021] (c) Set the time for ultrasonic treatment of SBS nanofiber membranes immersed in single-walled carbon nanotube solution;

[0022] (d) The SBS nanofiber membrane after ultrasonic treatment in step (c) is soaked for a set time, and then dried to obtain an SBS / CNT fiber membrane.

[0023] A second aspect of the present invention provides a flexible tensile sensor prepared based on the above method, comprising:

[0024] From bottom to top, they are the bottom membrane, the first intermediate membrane, the second intermediate membrane, and the top membrane.

[0025] The bottom layer and the second intermediate layer are both adhesive tape films, the first intermediate layer is an SBS / CNT fiber film, and the top layer is a conductive silicone layer.

[0026] A third aspect of the present invention provides a facial information perception system based on the above-described flexible stretch sensor, comprising:

[0027] The flexible stretch sensor has a surface that fits in contact with the face. When the face moves, it is stretched, which changes the resistance and generates a changing voltage signal that is sent to the processor.

[0028] The processor receives the voltage signal from the flexible tensile sensor, processes it, and outputs the result to the actuator.

[0029] The executor performs the corresponding action based on the processor's result.

[0030] Compared with existing technologies, one or more of the above technical solutions have the following beneficial effects:

[0031] 1. In terms of preparation process, styrene-butadiene-styrene block copolymer (SBS) is non-toxic and has good biocompatibility, and is unlikely to cause skin problems during long-term wear; SBS nanofiber membranes prepared by electrospinning have a unique three-dimensional skeleton. The high-porosity three-dimensional skeleton structure provides excellent breathability, which is conducive to balancing the heat and humidity relationship between the human body and the external environment, improving the comfort of sensor wear. At the same time, the process is low-cost, simple and can be mass-produced.

[0032] 2. In terms of performance, when the flexible tensile sensor is subjected to strain, the carbon black particles separate, causing a change in resistance. This change in resistance is transmitted through the conductive silicone layer on the top. The temperature response is caused by single-walled carbon nanotubes doped in the SBS fiber membrane. This allows the fabricated flexible tensile sensor to detect not only the resistance change caused by strain but also to respond well to temperature changes. As a result, the sensor can detect both strain and temperature signals, which can reflect the temperature of the wearable area in real time, detect the human body status, and achieve dual-mode signal detection.

[0033] 3. The resistive tensile sensor prepared by using SBS nanofiber membrane as a substrate can provide an ultra-wide range of strain capacity, with tensile deformation energy up to 250%, while the thickness is only about 100 micrometers, and it has good repeatability.

[0034] 4. Compared with existing application system designs, most application systems are designed based on computer platforms, which are inconvenient to carry. When the facial information perception system is built on an FPGA platform, it can be carried around and can perform real-time detection. In terms of detection speed, thanks to the parallel data processing method of FPGA, hardware acceleration of convolutional neural networks can be achieved. Attached Figure Description

[0035] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0036] Figure 1 This is a flowchart illustrating the fabrication process of a flexible tensile sensor provided in one or more embodiments of the present invention;

[0037] Figure 2 This is a three-dimensional structural schematic diagram of a flexible tensile sensor provided in one or more embodiments of the present invention;

[0038] Figure 3 This is a SEM (scanning electron microscope) image of the strain sensing layer of the flexible tensile sensor provided in one or more embodiments of the present invention;

[0039] Figure 4 This refers to the sensitivity of the strain sensing layer of the flexible tensile sensor provided by one or more embodiments of the present invention under small-range strain with different carbon black contents;

[0040] Figure 5 These are strain and temperature measurement graphs of a flexible tensile sensor provided in one or more embodiments of the present invention;

[0041] Figure 6 This is a schematic diagram of the maximum stretchable deformation of a flexible tensile sensor provided in one or more embodiments of the present invention;

[0042] Figure 7 This is a sensitivity test of the temperature sensing layer of the flexible tensile sensor provided in one or more embodiments of the present invention;

[0043] Figures 8(a)-(b) are schematic diagrams of the flexible stretch sensor provided by one or more embodiments of the present invention being worn on the hand;

[0044] Figure 9This is the signal transmission process of a detection and sensing system using a flexible tensile sensor provided in one or more embodiments of the present invention;

[0045] In the figure: 1-bottom membrane; 2-first intermediate membrane; 3-second intermediate membrane; 4-top membrane. Detailed Implementation

[0046] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0047] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0048] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0049] As described in the background section, current flexible stretch sensors have several drawbacks. Therefore, the following embodiments present a flexible stretch sensor, its fabrication method, and a facial information sensing system. This system features high sensitivity, low hysteresis, and good repeatability, and can be widely used in electronic skin, wearable products, implantable devices, and multifunctional sensor systems. A facial information sensing and control system based on FPGA is designed, which is portable and does not require a computer or other equipment, thus broadening the application scenarios of the flexible stretch sensor.

[0050] Example 1:

[0051] like Figure 1 As shown, the fabrication method of the flexible tensile sensor includes the following steps:

[0052] Electrode preparation involves adding carbon black to a solvent (e.g., n-hexane), stirring and ultrasonicating, adding silicone rubber, and then stirring and ultrasonicating again. By controlling different amounts of carbon black, conductive silicone with different initial resistances can be obtained.

[0053] The preparation of the substrate layer includes:

[0054] (1) Prepare a spinning solution and use electrospinning process to prepare styrene-butadiene-styrene block copolymer (SBS) film;

[0055] (2) Treat SBS nanofiber membranes with polydopamine solution to make them hydrophilic;

[0056] (3) The hydrophilically treated SBS nanofiber membrane was immersed in single-walled carbon nanotube (CNT) solutions of different concentrations and subjected to ultrasonic treatment for 10-40 min to allow it to enter the interfiber gaps and obtain SBS / CNT fiber membrane.

[0057] Assembly of the flexible stretch sensor: Tattoo stickers are attached to the upper and lower surfaces of the prepared SBS / CNT fiber membrane, and a layer of prepared conductive silicone is screen-printed on the top layer.

[0058] In step (1), the SBS spinning solution is prepared by dissolving granular SBS in a solvent to obtain a solution with a concentration of 7-10 wt%, and then magnetically stirring at 600-800 rpm for 8 hours to obtain a homogenized spinning solution, with the temperature set at 30-60℃.

[0059] In step (1), the solvent includes any one or a mixture of several of N,N-dimethylformamide, tetrahydrofuran, n-hexane, and alcohol.

[0060] Preferably, the concentration of the SBS spinning solution is 9 wt%.

[0061] In step (1), the preparation of the SBS nanofiber membrane is specifically as follows: the SBS fiber membrane is prepared by electrospinning, the spinning speed is 5-8 ml / h, the voltage is set to 16-24 kV, the receiving distance is set to 12-18 cm, and the spinning duration is 4-12 h.

[0062] In step (3), the preparation method of the SBS / CNT nanofiber membrane is as follows:

[0063] (a) Dilute the single-walled carbon nanotube solution to obtain single-walled carbon nanotube solutions of different concentrations;

[0064] (b) Immerse the hydrophilically treated SBS nanofiber membranes in carbon nanotube solutions of different concentrations for 1-8 hours for later use;

[0065] (c) The soaked SBS nanofiber membrane was ultrasonically dispersed in a single-walled carbon nanotube solution for 15-30 minutes and then set aside.

[0066] (d) Soak the SBS film after ultrasonic treatment in step (c) for another hour to obtain the final product.

[0067] The fabrication of the conductive silicone electrode is as follows:

[0068] (a) Dissolve 0.6g-1.2g of carbon black in 4.5g of n-hexane, stir for 15min-30min, and then sonicate the stirred sample for 15min-30min.

[0069] (b) Add 2g-3g of silicone rubber to the sample prepared in step (a), stir for 15min-30min, and then sonicate the stirred sample for 15min-30min to obtain the final product.

[0070] In terms of preparation process, styrene-butadiene-styrene block copolymer (SBS) is non-toxic and has good biocompatibility, and is unlikely to cause skin problems during long-term wear. The SBS nanofiber membrane prepared by electrospinning has a unique three-dimensional skeleton. The high porosity three-dimensional skeleton structure provides excellent breathability, which is conducive to balancing the heat and humidity relationship between the human body and the external environment, improving the comfort of sensor wear. At the same time, the process is low-cost, simple and can be mass-produced.

[0071] In terms of performance, when the flexible tensile sensor is subjected to strain, the carbon black particles separate, resulting in increased resistance and a change in resistance. This change in resistance is transmitted through the conductive silicone layer on the top. The temperature response is caused by single-walled carbon nanotubes doped in the SBS fiber membrane. This allows the fabricated flexible tensile sensor to detect not only the resistance change caused by strain but also to respond well to temperature changes. As a result, the sensor can detect both strain and temperature signals, which can reflect the temperature of the wearable area in real time, detect the human body's condition, and achieve dual-mode signal detection.

[0072] The resistance change caused by strain is generated by the top conductive silicone layer. When the prepared conductive silicone is screen-printed onto the substrate, hexane evaporates, leaving only an electrode layer. This electrode layer is conductive due to the presence of doped carbon black. When subjected to strain, the carbon black particles separate, leading to an increase in resistance and causing the resistance change. The temperature response is caused by single-walled carbon nanotubes doped in the SBS fiber membrane. Thermal expansion and contraction increase the conductive pathways of the carbon nanotubes, resulting in a decrease in resistance. The change in resistance is used to determine the temperature change. Therefore, benefiting from the advantages of the four-layer structure, the flexible tensile sensor in this embodiment can achieve dual-mode detection, which is more in line with the design of electronic skin.

[0073] The resistive tensile sensor fabricated using SBS nanofiber membrane as a substrate can provide an ultra-wide range of strain capacity, with tensile deformation energy up to 250%, while the thickness is only about 100 micrometers, and it has good repeatability.

[0074] Example 2:

[0075] The method for fabricating a flexible tensile sensor includes the following steps:

[0076] (1) Preparation of SBS spinning solution: SBS particles were dissolved in a DMF / THF (dimethylformamide / tetrahydrofuran) mixed solution to obtain a solution with a concentration of 9wt%. The magnetic stirrer was set to a speed of 600rpm and a temperature of 60℃ for 4 hours to obtain a uniform spinning solution.

[0077] (2) Preparation of SBS nanofiber membrane: SBS fiber membrane was prepared by electrospinning, wherein the spinning speed was 7 ml / h, the voltage was set to 18 kV, the receiving distance was set to 12 cm, and the spinning time lasted for 6 h.

[0078] (3) The fiber membrane collected in (2) is dried at room temperature and heat-treated, and then used to enhance the density of the fiber and improve the tensile properties of the SBS fiber membrane for later use.

[0079] (4) Hydrophilic treatment of SBS fiber membrane: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, disperse by ultrasonication for 30min, immerse the SBS fiber membrane prepared in (3) in the buffer solution, sonicate for 20min, and take it out after soaking for 4h, and dry it in a dryer at 60℃ for later use.

[0080] (5) Preparation of SBS / CNT fiber membrane: Take 2 ml of CNT aqueous solution, add 2 ml of deionized water, place it in an ultrasonic machine for 30 min, add the SBS fiber membrane prepared in (4) to the prepared CNT aqueous solution, ultrasonically disperse for 20 min, then soak for 2 h and take it out, place it in an oven at 60 degrees Celsius to dry, and obtain SBS / CNT fiber membrane.

[0081] (6) Preparation of conductive silicone electrode: 0.08g of carbon black was added to 4.5g of n-hexane solution. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain a uniform carbon black solution. Then, 2.5g of silicone rubber was added. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain conductive silicone. Figure 3 As shown;

[0082] (7) Sensor Assembly: Adhesive tape is applied to the top and bottom of the SBS / CNT fiber membrane in (5) to act as an insulating layer. A layer of conductive silicone is then screen-printed onto the adhesive tape to act as a strain layer. Figure 2 As shown.

[0083] Example 3:

[0084] The method for fabricating a flexible tensile sensor includes the following steps:

[0085] (1) Preparation of SBS spinning solution: SBS particles were dissolved in a DMF / THF mixed solution to obtain a solution with a concentration of 9wt%. The magnetic stirrer was set to a speed of 600 rpm and a temperature of 60℃ for 4 hours to obtain a uniform spinning solution.

[0086] (2) Preparation of SBS nanofiber membrane: SBS fiber membrane was prepared by electrospinning, wherein the spinning speed was 7 ml / h, the voltage was set to 18 kV, the receiving distance was set to 12 cm, and the spinning time lasted for 6 h.

[0087] (3) The fiber membrane collected in (2) is dried at room temperature and heat-treated, and then used to enhance the density of the fiber and improve the tensile properties of the SBS fiber membrane for later use.

[0088] (4) Hydrophilic treatment of SBS fiber membrane: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, disperse by ultrasonication for 30min, immerse the SBS fiber membrane prepared in (3) in the buffer solution, sonicate for 20min, and take it out after soaking for 4h, and dry it in a dryer at 60℃ for later use.

[0089] (5) Preparation of SBS / CNT fiber membrane: Take 2 ml of CNT aqueous solution, add 2 ml of deionized water, place it in an ultrasonic machine for 30 min, add the SBS fiber membrane prepared in (4) to the prepared CNT aqueous solution, ultrasonically disperse for 20 min, then soak for 2 h and take it out, place it in an oven at 60 degrees Celsius to dry, and obtain SBS / CNT fiber membrane.

[0090] (6) Preparation of conductive silicone electrode: 0.09g of carbon black was added to 4.5g of n-hexane solution. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain a uniform carbon black solution. Then, 2.5g of silicone rubber was added. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain conductive silicone. Figure 3 As shown;

[0091] (7) Sensor Assembly: Adhesive tape is applied to the top and bottom of the SBS / CNT fiber membrane in (5) to act as an insulating layer. A layer of conductive silicone is then screen-printed onto the adhesive tape to act as a strain layer. Figure 2 As shown.

[0092] Example 4:

[0093] The method for fabricating a flexible tensile sensor includes the following steps:

[0094] (1) Preparation of SBS spinning solution: SBS particles were dissolved in a DMF / THF mixed solution to obtain a solution with a concentration of 9wt%. The magnetic stirrer was set to a speed of 600 rpm and a temperature of 60℃ for 4 hours to obtain a uniform spinning solution.

[0095] (2) Preparation of SBS nanofiber membrane: SBS fiber membrane was prepared by electrospinning, wherein the spinning speed was 7 ml / h, the voltage was set to 18 kV, the receiving distance was set to 12 cm, and the spinning time lasted for 6 h.

[0096] (3) The fiber membrane collected in (2) is dried at room temperature and heat-treated, and then used to enhance the density of the fiber and improve the tensile properties of the SBS fiber membrane for later use.

[0097] (4) Hydrophilic treatment of SBS fiber membrane: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, disperse by ultrasonication for 30min, immerse the SBS fiber membrane prepared in (3) in the buffer solution, sonicate for 20min, and take it out after soaking for 4h, and dry it in a dryer at 60℃ for later use.

[0098] (5) Preparation of SBS / CNT fiber membrane: Take 2 ml of CNT aqueous solution, add 2 ml of deionized water, place it in an ultrasonic machine for 30 min, add the SBS fiber membrane prepared in (4) to the prepared CNT aqueous solution, ultrasonically disperse for 20 min, then soak for 2 h and take it out, place it in an oven at 60 degrees Celsius to dry, and obtain SBS / CNT fiber membrane.

[0099] (6) Preparation of conductive silicone electrode: 0.1g of carbon black was added to 4.5g of n-hexane solution. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain a uniform carbon black solution. Then, 2.5g of silicone rubber was added. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain conductive silicone. Figure 3 As shown;

[0100] (7) Sensor Assembly: Adhesive tape is applied to the top and bottom of the SBS / CNT fiber membrane in (5) to act as an insulating layer. A layer of conductive silicone is then screen-printed onto the adhesive tape to act as a strain layer. Figure 2 As shown.

[0101] Example 5:

[0102] The method for fabricating a flexible tensile sensor includes the following steps:

[0103] (1) Preparation of SBS spinning solution: SBS particles were dissolved in a DMF / THF mixed solution to obtain a solution with a concentration of 9wt%. The magnetic stirrer was set to a speed of 600 rpm and a temperature of 60℃ for 4 hours to obtain a uniform spinning solution.

[0104] (2) Preparation of SBS nanofiber membrane: SBS fiber membrane was prepared by electrospinning, wherein the spinning speed was 7 ml / h, the voltage was set to 18 kV, the receiving distance was set to 12 cm, and the spinning time lasted for 6 h.

[0105] (3) The fiber membrane collected in (2) is dried at room temperature and heat-treated, and then used to enhance the density of the fiber and improve the tensile properties of the SBS fiber membrane for later use.

[0106] (4) Hydrophilic treatment of SBS fiber membrane: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, disperse by ultrasonication for 30min, immerse the SBS fiber membrane prepared in (3) in the buffer solution, sonicate for 20min, and take it out after soaking for 4h, and dry it in a dryer at 60℃ for later use.

[0107] (5) Preparation of SBS / CNT fiber membrane: Take 2 ml of CNT aqueous solution, add 2 ml of deionized water, place it in an ultrasonic machine for 30 min, add the SBS fiber membrane prepared in (4) to the prepared CNT aqueous solution, ultrasonically disperse for 20 min, then soak for 2 h and take it out, place it in an oven at 60 degrees Celsius to dry, and obtain SBS / CNT fiber membrane.

[0108] (6) Preparation of conductive silicone electrode: 0.11g of carbon black was added to 4.5g of n-hexane solution. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain a uniform carbon black solution. Then, 2.5g of silicone rubber was added. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain conductive silicone. Figure 3 As shown;

[0109] (7) Sensor Assembly: Adhesive tape is applied to the top and bottom of the SBS / CNT fiber membrane in (5) to act as an insulating layer. A layer of conductive silicone is then screen-printed onto the adhesive tape to act as a strain layer. Figure 2 As shown.

[0110] Example 6:

[0111] The method for fabricating a flexible tensile sensor includes the following steps:

[0112] (1) Preparation of SBS spinning solution: SBS particles were dissolved in a DMF / THF mixed solution to obtain a solution with a concentration of 9wt%. The magnetic stirrer was set to a speed of 600 rpm and a temperature of 60℃ for 4 hours to obtain a uniform spinning solution.

[0113] (2) Preparation of SBS nanofiber membrane: SBS fiber membrane was prepared by electrospinning, wherein the spinning speed was 7 ml / h, the voltage was set to 18 kV, the receiving distance was set to 12 cm, and the spinning time lasted for 6 h.

[0114] (3) The fiber membrane collected in (2) is dried at room temperature and heat-treated, and then used to enhance the density of the fiber and improve the tensile properties of the SBS fiber membrane for later use.

[0115] (4) Hydrophilic treatment of SBS fiber membrane: Dissolve 0.01g of polydopamine in a buffer solution with a pH of 8.5, disperse by ultrasonication for 30min, immerse the SBS fiber membrane prepared in (3) in the buffer solution, sonicate for 20min, and take it out after soaking for 4h, and dry it in a dryer at 60℃ for later use.

[0116] (5) Preparation of SBS / CNT fiber membrane: Take 2 ml of CNT aqueous solution, add 2 ml of deionized water, place it in an ultrasonic machine for 30 min, add the SBS fiber membrane prepared in (4) to the prepared CNT aqueous solution, ultrasonically disperse for 20 min, then soak for 2 h and take it out, place it in an oven at 60 degrees Celsius to dry, and obtain SBS / CNT fiber membrane.

[0117] (6) Preparation of conductive silicone electrode: 0.12g of carbon black was added to 4.5g of n-hexane solution. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain a uniform carbon black solution. Then, 2.5g of silicone rubber was added. The magnetic stirrer was set to 600 rpm and 60℃ for 15 min, followed by ultrasonic dispersion for 15 min to obtain conductive silicone. Figure 3 As shown;

[0118] (7) Sensor Assembly: Adhesive tape is applied to the top and bottom of the SBS / CNT fiber membrane in (5) to act as an insulating layer. A layer of conductive silicone is then screen-printed onto the adhesive tape to act as a strain layer. Figure 2 As shown.

[0119] Example 7:

[0120] The flexible tensile sensor prepared based on the method of Example 1 includes:

[0121] From bottom to top, they are: bottom membrane 1, first intermediate membrane 2, second intermediate membrane 3, and top membrane 4;

[0122] Among them, the bottom film 1 is a sticker tape film, the first intermediate film 2 is an SBS / CNT fiber film, the second intermediate film 3 is a sticker tape insulating layer, and the top film 4 is a conductive silicone layer.

[0123] The first intermediate membrane 2 and the top membrane 4 serve as active layers. The SBS / CNT fiber membrane detects temperature signals. Temperature changes cause the CNTs to expand and contract, resulting in changes in the conductive path and resistance, thus sensing the temperature. The conductive silicone layer detects strain signals. Strain causes changes in the distance between carbon black particles, resulting in changes in resistance, thus detecting the strain.

[0124] The bottom membrane 1 and the second intermediate membrane 3 not only serve as an insulator, but also facilitate the connection between the bottom membrane and the other layers, thereby fabricating an ultrathin and dual-mode flexible stretch sensor.

[0125] According to the methods in Examples 2-6, five conductive silicone materials with different carbon black contents were used to prepare flexible tensile sensors. Small-range tensile sensitivity tests were conducted, and the test results are as follows: Figure 4 As shown.

[0126] Tests were conducted with a strain of 10% and a temperature change of 20°C. The test results are as follows: Figure 5 As shown, it can be seen that the resistance increases when strain occurs, while the resistance decreases when the temperature rises due to the thermal expansion and contraction principle of carbon nanotubes, which leads to more conductive paths.

[0127] Tensile tests were performed on the prepared flexible tensile sensor, and the results were as follows: Figure 6 As shown, the maximum stretch length can reach 250%, so the fabricated flexible tensile sensor exhibits excellent tensile properties, and the thickness is only about 100 micrometers.

[0128] In addition, SBS / CNT fiber membranes also exhibited good temperature response capabilities, such as... Figure 7 As shown, when the temperature rises from 0℃ to 80℃, the resistance of the nanofiber membrane changes by 70% relative to the initial resistance, demonstrating good temperature detection capability.

[0129] Furthermore, both SBS / CNT fiber films and adhesive tapes possess excellent tensile strength and good skin compatibility, such as... Figures 8(a)-8(b) As shown, no discomfort symptoms such as redness, swelling or itching occurred after prolonged wear, indicating that the SBS / CN T fiber membrane and adhesive tape have good biocompatibility, and the prepared sensor is suitable for long-term wear.

[0130] Example 8:

[0131] The facial information perception system designed based on the flexible tensile sensor prepared by the method in Example 1 includes:

[0132] The flexible stretch sensor has a surface that fits in contact with the face. When the face moves, it is stretched, which changes the resistance and generates a changing voltage signal that is sent to the processor.

[0133] The processor receives the voltage signal from the flexible tensile sensor, processes it, and outputs the result to the actuator.

[0134] The executor performs the corresponding action based on the processor's result.

[0135] By attaching a flexible stretch sensor to a human face, the resulting sensor generates a change in resistance and voltage upon movement. This change is recognized by a neural network in the signal system, and the result is transmitted via serial port to the controlled object to execute the corresponding action. For example, facial movements can be used to control a robotic arm to grasp a target object. Figure 9 As shown.

[0136] In this embodiment, the voltage can be acquired by the AD7606 module driven by the FPGA development board, then identified by the neural network recognition module in the FPGA, and based on the judgment, real-time control commands are sent to the robot to perform the target operation.

[0137] Most application systems are designed based on computer platforms, which are inconvenient to carry. When a facial information perception system is built on an FPGA platform, it can be carried around and can perform real-time detection. In terms of detection speed, thanks to the parallel data processing method of FPGA, hardware acceleration of convolutional neural networks can be achieved.

[0138] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for fabricating a flexible tensile sensor, characterized in that, Includes the following steps: A spinning solution was prepared, and a styrene-butadiene-styrene block copolymer film, i.e., an SBS nanofiber membrane, was prepared using an electrospinning process. The SBS nanofiber membrane was then hydrophilically treated. The hydrophilic treatment of the SBS nanofiber membrane specifically involved: Polydopamine is dissolved in an alkaline buffer solution and ultrasonically treated. SBS nanofiber membranes are immersed in the ultrasonically treated polydopamine solution for a set time, then removed and dried to complete the hydrophilic treatment. The spinning solution is prepared as follows: Particulate styrene-butadiene-styrene block copolymer was dissolved in a solvent to obtain a solution with a concentration of 7-10 wt%, and stirred to obtain a homogenized spinning solution; the concentration of the SBS spinning solution was 9 wt%. The hydrophilically treated SBS nanofiber membrane was immersed in single-walled carbon nanotube solutions of different concentrations and then subjected to ultrasonic treatment to obtain a styrene-butadiene-styrene block copolymer / single-walled carbon nanotube fiber membrane, namely SBS / CNT fiber membrane. The temperature response is caused by single-walled carbon nanotubes doped in the SBS fiber membrane, which enables the prepared flexible tensile sensor to not only detect the resistance change caused by strain, but also to respond well to temperature changes. This allows the sensor to detect not only strain signals but also temperature signals, which can reflect the temperature of the wearable part in real time, detect the human body status, and realize dual-mode signal detection. The prepared SBS / CNT fiber membrane has adhesive tape pasted on both the upper and lower surfaces as a separator layer. Conductive silicone is screen-printed onto the separator layer on the upper surface, and after cutting, a flexible tensile sensor is obtained.

2. The method for preparing the flexible tensile sensor as described in claim 1, characterized in that, The preparation process of conductive silicone is as follows: Carbon black is added to a solvent, stirred and ultrasonically treated, then silicone rubber is added, and the mixture is stirred and ultrasonically treated again to obtain conductive silicone.

3. The method for preparing the flexible tensile sensor as described in claim 2, characterized in that, In the preparation process of conductive silicone, conductive silicone with different initial resistances can be obtained by controlling different contents of carbon black.

4. The method for preparing the flexible tensile sensor as described in claim 1, characterized in that, The solvent includes any one or a mixture of several of N,N-dimethylformamide, tetrahydrofuran, n-hexane, and alcohol.

5. The method for preparing the flexible tensile sensor as described in claim 1, characterized in that, The preparation of SBS nanofiber membranes is as follows: SBS fiber membranes were prepared by electrospinning at a speed of 5-8 ml / h, a voltage of 16-24 kV, a receiving distance of 12-18 cm, and a spinning duration of 4-12 h.

6. The method for preparing the flexible tensile sensor as described in claim 1, characterized in that, The SBS / CNT fiber membrane was obtained as follows: (a) Dilute the single-walled carbon nanotube solution to obtain a single-walled carbon nanotube solution of the desired concentration; (b) Immerse the hydrophilically treated SBS nanofiber membrane in a carbon nanotube solution of the required concentration for a set time; (c) Set the time for ultrasonic treatment of SBS nanofiber membranes immersed in single-walled carbon nanotube solution; (d) The SBS nanofiber membrane after ultrasonic treatment in step (c) is soaked for a set time, and then dried to obtain an SBS / CNT fiber membrane.

7. A flexible tensile sensor obtained by the preparation method according to any one of claims 1-6, characterized in that, include: From bottom to top, the layers are: bottom membrane, first intermediate membrane, second intermediate membrane, and top membrane. The bottom layer and the second intermediate layer are both adhesive tape films, the first intermediate layer is an SBS / CNT fiber film, and the top layer is a conductive silicone layer.

8. A facial information perception system constructed based on the flexible stretch sensor described in claim 7, characterized in that, include: The flexible stretch sensor has a surface that fits in contact with the face. When the face moves, it is stretched, which changes the resistance and generates a changing voltage signal that is sent to the processor. The processor receives the voltage signal from the flexible tensile sensor, processes it, and outputs the result to the actuator. The executor performs the corresponding action based on the processor's result.

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