Preparation method of strain sensor and strain sensor

Abstract

The embodiment of the invention provides a preparation method of a strain sensor, and the method comprises the steps: dipping spandex fibers into waterborne polyurethane, moving out, and airing, so as to obtain a flexible substrate layer; dipping the flexible substrate layer into a mixed solution of graphene, N-CNTs and PVP, and then moving out and airing the flexible substrate layer to obtain a core sensitive layer; and performing thin film packaging on the core sensitive layer to obtain the strain sensor. The strain sensor prepared by the preparation method of the strain sensor provided by the embodiment of the invention has relatively good flexibility, fitting property, skin-friendly property, elasticity and repeatability, has high sensitivity and relatively wide response range, and is particularly suitable for recognition of hand movement. The embodiment of the invention also provides a strain sensor.

Description

Technical Field

[0001] The embodiments of the present application relate to the field of sensor technology, and in particular to a method for preparing a strain sensor and a strain sensor. Background Art

[0002] Hand motion recognition has important applications in medical rehabilitation, virtual reality, and human-computer interaction. Strain sensors can capture subtle movements of fingers and palms, providing accurate data for practical applications.

[0003] However, current strain sensors have many shortcomings, such as slow response speed, low sensitivity, small response range, poor stability and large device size, which limit the effectiveness of strain sensors in practical applications. Summary of the Invention

[0004] To achieve the above objectives, the embodiments of the present application provide a method for preparing a strain sensor and a strain sensor, so that the strain sensor has good flexibility, conformability, skin-friendliness, elasticity and repeatability, and has high sensitivity and a wide response range, which is particularly suitable for identifying hand movements.

[0005] In a first aspect, an embodiment of the present application provides a method for preparing a strain sensor, comprising:

[0006] The spandex fiber is immersed in water-based polyurethane, removed and dried to obtain a flexible base layer;

[0007] Immersing the flexible substrate layer in a mixture of graphene, N-CNTs and PVP, removing the flexible substrate layer and air-drying the mixture to obtain a core sensitive layer; and

[0008] The core sensitive layer is encapsulated with a thin film to obtain the strain sensor.

[0009] Furthermore, the mass ratio of graphene, N-CNTs and PVP in the core sensitive layer is 3:1:0.3 to 10:1:0.3; and / or the number of immersions is greater than or equal to 2 times; and / or the drying time is 10 to 25 seconds; and / or the drying temperature is room temperature.

[0010] Furthermore, before immersing the flexible substrate layer in the mixed solution of graphene, N-CNTs and PVP and removing it to dry to obtain the core sensitive layer, the method further comprises:

[0011] Graphene, N-CNTs and PVP sensitive material are mixed, ethanol solution is added and fully stirred, and ultrasonic dispersion is performed to obtain a mixed solution of graphene, N-CNTs and PVP.

[0012] Furthermore, the graphene, N-CNTs and PVP sensitive material are mixed, an ethanol solution is added and fully stirred, and ultrasonic dispersion is performed to obtain a mixed solution of graphene, N-CNTs and PVP, comprising:

[0013] Weighing a preset amount of graphene, adding a preset amount of N-CNTs, PVP and ethanol solution into a magnetic stirrer for stirring to obtain a preliminary mixed solution of graphene, N-CNTs and PVP; and

[0014] The preliminary mixed solution is placed in an ultrasonic cleaning machine for ultrasonic dispersion to obtain the graphene, N-CNTs and PVP mixed solution.

[0015] Furthermore, the corresponding ratio of the graphene and the ethanol solution is 5 ml of ethanol solution per 150 mg of graphene; and / or the stirring temperature is room temperature; and / or the drying temperature is room temperature; and / or the stirring time is 2 h to 3 h; and / or the ultrasonic dispersion time is 0.5 h to 1 h.

[0016] Furthermore, before performing thin film packaging on the core sensitive layer to obtain the strain sensor, the method further includes:

[0017] The core sensitive layer is led out through a metal wire.

[0018] Furthermore, the step of leading out the core sensitive layer through a metal wire includes:

[0019] The edges of the core sensitive layer are cured with conductive silver paste; and

[0020] The metal wire is wound around the solidified conductive silver paste.

[0021] Furthermore, the heating and curing time of the conductive silver paste is 1.5 hours to 2.5 hours; and / or the heating and curing temperature of the conductive silver paste is 70° C. to 90° C.

[0022] Furthermore, the core sensitive layer is thin-film encapsulated to obtain the strain sensor, comprising:

[0023] mixing the solutions to obtain an ecoflex mixture; and

[0024] The core sensitive layer is immersed in the ecoflex mixed liquid, removed and hung in the air to dry, thereby obtaining the strain sensor.

[0025] In a second aspect, an embodiment of the present application provides a strain sensor, which is manufactured using any of the manufacturing methods described above.

[0026] In the strain sensor preparation method provided in the embodiments of the present application, spandex fibers are first immersed in water-based polyurethane, removed and air-dried to obtain a flexible base layer. The flexible base layer is then immersed in a mixture of graphene, N-CNTs, and PVP, removed and air-dried to obtain a core sensitive layer. Finally, the core sensitive layer is thin-film encapsulated to obtain a strain sensor. The strain sensor prepared by the strain sensor preparation method provided in the embodiments of the present application not only has good flexibility, conformability, skin-friendliness, elasticity, and repeatability, but also has high sensitivity and a wide response range, making it particularly suitable for identifying hand movements. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on the structures shown in these drawings without paying any creative work.

[0028] Figure 1 A schematic diagram of a process for preparing a strain sensor according to an embodiment of the present application;

[0029] Figure 2 A schematic diagram of the structure of the strain sensor provided in an embodiment of the present application;

[0030] Figure 3 A schematic diagram of a scanning electron microscope of a strain sensor provided in an embodiment of the present application;

[0031] Figure 4 This is a stability test diagram of the strain sensor according to an embodiment of the present application under different frequency conditions;

[0032] Figure 5 1 is a step diagram of different tensile responses of the strain sensor according to an embodiment of the present application.

[0033] The realization of the objectives, functional features and advantages of this application will be further explained in conjunction with embodiments and with reference to the accompanying drawings. DETAILED DESCRIPTION

[0034] In order to make the technical problems, technical solutions and beneficial effects solved by the embodiments of the present application more clearly understood, the embodiments of the present application are further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present application.

[0035] The following describes in detail embodiments of the present application, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are intended to be used to explain the present application, and should not be construed as limiting the present application.

[0036] In the description of the embodiments of the present application, it should be understood that the terms "lateral", "length", "width", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "clockwise", "counterclockwise", etc., indicating the orientation or position relationship, are based on the orientation or position relationship shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application.

[0037] In addition, the terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include at least one of the features. In the description of the embodiments of the present application, the meaning of "plurality" is at least two, for example, two, three, etc., unless otherwise clearly and specifically defined.

[0038] In the embodiments of the present application, unless otherwise specified or limited, the terms "installed," "connected," "connected," "fixed," etc. should be understood in a broad sense. For example, they can refer to fixed connections, detachable connections, or integration; mechanical connections, electrical connections; direct connections, or indirect connections through an intermediate medium; internal connections between two components, or interactions between two components, unless otherwise specified. Those skilled in the art can understand the specific meanings of the above terms in the embodiments of the present application based on specific circumstances.

[0039] In the embodiments of the present application, unless otherwise expressly specified or limited, a first feature being "above" or "below" a second feature may mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, a first feature being "above," "above," and "above" a second feature may mean that the first feature is directly above or obliquely above the second feature, or simply means that the first feature is higher in level than the second feature. A first feature being "below," "below," and "below" a second feature may mean that the first feature is directly below or obliquely below the second feature, or simply means that the first feature is lower in level than the second feature.

[0040] Reference Figure 1 and Figure 2, an embodiment of the present application provides a method for preparing a strain sensor 100, comprising the following steps:

[0041] Step 1: dipping the spandex fiber into waterborne polyurethane and removing it to dry, thereby obtaining a flexible base layer 101;

[0042] Specifically, spandex fiber, short for polyurethane (PU), is a type of elastic fiber. Generally composed of multiple filaments, spandex fiber is highly elastic and can be stretched 6-7 times, yet quickly returns to its original state once the tension is removed. The spandex fiber used in some embodiments of this application is 1680D.

[0043] Waterborne polyurethane (also known as water-dispersible polyurethane, water-based polyurethane, or water-based polyurethane) is a new type of polyurethane system that uses water as the dispersion medium instead of organic solvents. Using water as the solvent, waterborne polyurethane offers advantages such as being pollution-free, safe and reliable, with excellent mechanical properties, good compatibility, and ease of modification.

[0044] Therefore, the flexible base layer 101 can be obtained by immersing the spandex fiber into aqueous polyurethane and removing it to dry. For example, the flexible base layer 101 can be obtained by immersing 1680D spandex fiber into aqueous polyurethane with a solid content of 60% for 3 seconds and then removing it and drying it for 45 seconds. The obtained flexible base layer 101 has good elasticity and has the advantages of being non-toxic and environmentally friendly.

[0045] Step 2: dipping the flexible substrate layer 101 into a mixture of graphene, N-CNTs and PVP, and then removing and drying the mixture to obtain a core sensitive layer 102; and

[0046] Specifically, graphene is an allotrope of carbon, with carbon atoms arranged in sp 2 Hybrid bonding forms a single-layer hexagonal honeycomb lattice graphene. N-CNTs (Carbon-nitrogen Nanotubes, nitrogen-doped carbon nanotubes) are a special type of carbon nanotubes in which some carbon atoms are replaced or added by nitrogen atoms, thus forming nitrogen-doped carbon nanotubes. This doping can change the electronic structure and surface properties of carbon nanotubes, enhancing their chemical reactivity and specific functions. Nitrogen-doped carbon nanotubes have excellent mechanical properties, electrical conductivity and chemical stability. PVP (Polyvinyl pyrrolidone, polyvinyl pyrrolidone) is a synthetic water-soluble polymer compound with the general properties of water-soluble polymer compounds, including colloidal protection, film-forming properties, adhesion, hygroscopicity, solubilization or coagulation.

[0047] Reference Figure 3The microstructure of the core sensitive layer 102 of the strain sensor prepared in the embodiment of the present invention is a conductive network formed by one-dimensional carbon nanotubes and two-dimensional graphene. The large surface area of ​​graphene provides a wide response range, and the defective connection of carbon nanotubes provides high sensitivity. Figure 3 In the electron microscope image, linear and flake-like objects are seen.

[0048] Step three: performing thin film packaging on the core sensitive layer 102 to form a packaging layer 103 , thereby obtaining the strain sensor 100 .

[0049] After the flexible base layer 101 and the core sensitive layer 102 are prepared, a packaging operation is required, that is, a thin film packaging is performed outside the core sensitive layer 102 to form a packaging layer 103, thereby obtaining the strain sensor 100.

[0050] Therefore, in the preparation method of the strain sensor provided in the embodiment of the present application, the spandex fiber is first immersed in water-based polyurethane and removed to dry to obtain a flexible base layer; then the flexible base layer is immersed in a mixture of graphene, N-CNTs and PVP and removed to dry to obtain a core sensitive layer; finally, the core sensitive layer is thin-film encapsulated to obtain a strain sensor. Figure 4 It can be seen that the strain sensor manufactured according to the preparation method of the strain sensor provided in the embodiment of the present application maintains the same response capability under cyclic stretching of different frequencies. Figure 5 This is a step diagram showing the different stretch responses of the strain sensor of the present invention. The left side shows the stretch step, and the right side shows the relaxation step. It can be seen that the stretch and relaxation steps are distinct, with almost identical gradients. Therefore, the strain sensor fabricated by the strain sensor preparation method provided in the present invention not only exhibits excellent flexibility, conformability, skin-friendliness, elasticity, and repeatability, but also has high sensitivity and a wide response range, making it particularly suitable for identifying hand movements.

[0051] Furthermore, in some embodiments of the present application, the mass ratio of graphene, N-CNTs and PVP in the core sensitive layer 102 is 3:1:0.3 to 10:1:0.3; and / or; the number of immersion times is greater than or equal to 2 times; and / or, the drying time is 10 to 25 seconds; and / or, the drying temperature is room temperature.

[0052] It should be noted that the mass ratio of graphene to N-CNTs in the core sensitive layer 102 is preferably 3:1. The number of immersions is greater than or equal to 2 times, which means that step 1 and / or step 2 described above are repeated two or more times. For example, the flexible substrate layer 101 is immersed twice in the mixture of graphene, N-CNTs and PVP and then removed and dried to obtain the core sensitive layer 102, thereby ensuring that the core sensitive layer 102 meets actual needs.

[0053] It is worth noting that the parameters mentioned above are only examples. The specific values ​​depend on the actual situation and are not limited here.

[0054] Furthermore, in some embodiments of the present application, before immersing the flexible substrate layer 101 in a mixture of graphene, N-CNTs and PVP and removing it to dry to obtain the core sensitive layer 102, the process includes: mixing the graphene, N-CNTs and PVP sensitive materials, adding an ethanol solution and stirring it thoroughly, and obtaining a mixture of graphene, N-CNTs and PVP by ultrasonic dispersion, thereby preparing for the preparation of the core sensitive layer and ensuring that the core sensitive layer meets the usage requirements.

[0055] Furthermore, in some embodiments of the present application, the graphene, N-CNTs and PVP sensitive material are mixed, an ethanol solution is added and fully stirred, and ultrasonic dispersion is performed to obtain a mixed solution of graphene, N-CNTs and PVP, comprising:

[0056] Weighing a preset amount of graphene, adding a preset amount of N-CNTs, PVP and ethanol solution into a magnetic stirrer for stirring to obtain a preliminary mixed solution of graphene, N-CNTs and PVP; and

[0057] The preliminary mixed solution is placed in an ultrasonic cleaning machine for ultrasonic dispersion to obtain the graphene, N-CNTs and PVP mixed solution.

[0058] Specifically, a certain amount of graphene is weighed, and nitrogen-doped carbon nanotubes (N-CNTs) and PVP are added. The mass ratio of graphene, N-CNTs, and PVP is 3:1:0.3. The mixture of graphene, N-CNTs, and PVP is then ultrasonically dispersed to obtain a graphene / N-CNTs / PVP mixture. The K value of PVP is typically 30.

[0059] Furthermore, in some embodiments of the present application, the corresponding ratio of the graphene and the ethanol solution is 5 ml of ethanol solution per 150 mg of graphene; and / or the stirring temperature is room temperature; and / or the drying temperature is room temperature; and / or the stirring time is 2 h to 3 h; and / or the ultrasonic dispersion time is 0.5 h to 1 h.

[0060] It is worth noting that the parameters mentioned above are only examples. The specific values ​​depend on the actual situation and are not limited here.

[0061] Furthermore, in some embodiments of the present application, before performing thin film packaging on the core sensitive layer to obtain the strain sensor, the method further includes:

[0062] The core sensitive layer 102 is led out through a metal wire.

[0063] That is, two edges of the core sensitive layer 102 are connected to the lead-out electrodes by winding metal wires, and the metal wires include at least one of copper, silver and conductive glue.

[0064] Furthermore, the step of leading the core sensitive layer 102 out through a metal wire includes:

[0065] The edges of the core sensitive layer 102 are cured with conductive silver paste; and

[0066] The metal wire is wound around the solidified conductive silver paste.

[0067] Specifically, after obtaining the graphene and N-CNTs / PVP core sensitive layer 102, the two ends of the graphene and N-CNTs / PVP core sensitive layer 102 are immersed in conductive silver paste and shaken evenly, and then placed on a heating table for heating and curing. The metal wire is wrapped around the solidified conductive silver paste, which is more conducive to improving its fit, accuracy, sensitivity, stability and service life.

[0068] Furthermore, in some embodiments of the present application, the heating and curing time of the conductive silver paste is 1.5h to 2.5h; and / or, the heating and curing temperature of the conductive silver paste is 70°C to 90°C, thereby ensuring that the conductive silver paste can be evenly and firmly attached to the core sensitive layer 102.

[0069] Furthermore, in some embodiments of the present application, the thin film encapsulation of the core sensitive layer 102 to obtain the strain sensor includes:

[0070] mixing the solutions to obtain an ecoflex mixture; and

[0071] The core sensitive layer 102 is immersed in the ecoflex mixed liquid, then removed and hung in the air to dry, thereby obtaining the strain sensor 100 .

[0072] Specifically, in some embodiments of the present application, Ecoflex liquids A and B are mixed to obtain an Ecoflex mixed solution. The core sensitive layer 102 is immersed in the Ecoflex mixed solution for 3 seconds, then removed and hung to dry to obtain the strain sensor 100. In practical applications, the thickness of the Ecoflex film encapsulation layer is typically 0.5 mm to 1.5 mm.

[0073] It should be noted that Ecoflex mixture is an elastomeric compound composed of at least 95% silicon, with the remaining ingredients including plasticizers, heat stabilizers, and UV stabilizers. This material can be used for a long time in a temperature range of -65°C to 200°C while maintaining its soft and elastic properties.

[0074] In addition, the present embodiment provides a strain sensor 100, which is manufactured using the manufacturing method described above. The strain sensor 100 of the present embodiment is manufactured using the manufacturing method described above. For details, please refer to the description of the method section, which will not be repeated here.

[0075] The above description is only a preferred embodiment of the present application and does not limit the patent scope of the present application. All equivalent structural transformations made based on the contents of the present application specification and drawings, or direct / indirect application in other related technical fields, are included in the patent protection scope of the present application.

Claims

1. A method for preparing a strain sensor, characterized in that: include: The spandex fiber is immersed in water-based polyurethane, removed and air-dried to obtain a flexible base layer; The flexible substrate layer is immersed in a mixed solution of graphene, N-CNTs and PVP, and then removed and air-dried to obtain a core sensitive layer; and The core sensitive layer is thin-film packaged to obtain the strain sensor.

2. The method according to claim 1, characterized in that The mass ratio of graphene, N-CNTs and PVP in the core sensitive layer is 3:1:0.3 to 10:1:0.3; and / or; the number of immersion times is greater than or equal to 2 times; and / or, the drying time is 10 to 25 seconds; and / or, the drying temperature is room temperature.

3. The method according to claim 2, characterized in that Before the flexible substrate layer is immersed in the mixed solution of graphene, N-CNTs and PVP and then removed and dried to obtain the core sensitive layer, the method comprises: Graphene, N-CNTs and PVP sensitive material are mixed, ethanol solution is added and fully stirred, and ultrasonic dispersion is performed to obtain a mixed solution of graphene, N-CNTs and PVP.

4. The method according to claim 3, characterized in that The graphene, N-CNTs and PVP sensitive material are mixed, an ethanol solution is added and fully stirred, and ultrasonic dispersion is performed to obtain a mixed solution of graphene, N-CNTs and PVP, comprising: Weighing a preset amount of graphene, adding a preset amount of N-CNTs, PVP and ethanol solution into a magnetic stirrer for stirring to obtain a preliminary mixed solution of graphene, N-CNTs and PVP; and The preliminary mixed solution is placed in an ultrasonic cleaning machine for ultrasonic dispersion to obtain the graphene, N-CNTs and PVP mixed solution.

5. The method according to claim 4, characterized in that The corresponding ratio of the graphene to the ethanol solution is 5 ml of ethanol solution for every 150 mg of graphene; and / or the stirring temperature is room temperature; and / or the drying temperature is room temperature; and / or the stirring time is 2h to 3h; and / or the ultrasonic dispersion time is 0.5h to 1h.

6. The method according to claim 1, characterized in that Before the core sensitive layer is thin-film packaged to obtain the strain sensor, the method further includes: The core sensitive layer is led out through a metal wire.

7. The method according to claim 6, characterized in that Leading out the core sensitive layer through a metal wire includes: The edges of the core sensitive layer are cured with conductive silver paste; and The metal wire is coiled around the cured conductive silver paste.

8. The method according to claim 7, characterized in that The heating curing time of the conductive silver paste is 1.5 hours to 2.5 hours; and / or the heating curing temperature of the conductive silver paste is 70° C. to 90° C.

9. The method according to claim 1, characterized in that The step of performing thin film packaging on the core sensitive layer to obtain the strain sensor comprises: mixing the solutions to obtain an ecoflex mixed solution; and The core sensitive layer is immersed in the ecoflex mixed solution, then removed and hung in the air to dry, thereby obtaining the strain sensor.

10. A strain sensor, characterized in that: The strain sensor is manufactured by the manufacturing method according to any one of claims 1 to 9.

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