Preparation method of fluorescent self-warning tactile sensor and sensor

Abstract

The invention relates to the technical field of sensor preparation, in particular to a preparation method of a fluorescent self-warning tactile sensor and the sensor, and the preparation method comprises the following steps: mixing CQDs and N, N-dimethylformamide, mixing PVDF and a CQDs suspension, and mixing a first mixed solution with an additive to obtain a PVDF / CQDs mixed solution; adsorbing the CQDs suspension in the cellulose porous framework to obtain a first framework; a PVDF / CQDs mixed solution is infiltrated into the first framework object, and a first functional film is obtained; and assembling the first functional film and the ITO-PEN electrode to obtain the fluorescent self-warning tactile sensor. The degradable cellulose porous framework is used as a main piezoelectric material, the PVDF piezoelectric material is used as an auxiliary material, the CQDs are coupled, the piezoelectric and fluorescent dual functions are achieved, and meanwhile the self function and high flexibility are kept. The cellulose porous framework has a developed porous structure orderly formed by fine fibers, provides a framework for dispersion adsorption of the CQDs, and solves the problem of solid fluorescence quenching of the CQDs, so that colorful fluorescence is excited under ultraviolet light.

Description

Technical Field

[0001] The present invention relates to the technical field of sensor preparation, and particularly relates to a preparation method and a sensor of a fluorescence self-warning tactile sensor. Background Art

[0002] With the rapid development of artificial intelligence, wearable electronic devices, intelligent robots, and human-computer interaction technologies, tactile sensors, as key components for perceiving external mechanical stimuli, have become increasingly important. Tactile sensors not only need to have high sensitivity, high resolution, and fast response capabilities, but also need to meet emerging requirements such as multi-functionality, self-powered, and high flexibility to adapt to complex and changing application scenarios. However, traditional tactile sensors mostly use rigid materials and single-function designs, making it difficult to meet the urgent needs of modern intelligent systems for flexibility, self-powered, and multi-function integration.

[0003] In recent years, flexible piezoelectric materials have become a research hotspot for tactile sensors because they can convert mechanical energy into electrical energy and achieve self-powered characteristics. Among them, polyvinylidene fluoride (PVDF) and its derivatives (such as PVDF-TrFE, PVDF-HFP) have been widely used as sensitive materials for tactile sensors due to their excellent piezoelectric properties and flexibility. However, PVDF-based sensors have a single function and are difficult to meet multi-functional requirements.

[0004] Therefore, how to endow tactile sensors with more functions is a current research direction. Summary of the Invention

[0005] (I) Object of the Invention

[0006] The object of the present invention is to provide a preparation method and a sensor of a fluorescence self-warning tactile sensor that meet the requirements of multi-functionality, high flexibility, and self-powered.

[0007] (II) Technical Solution

[0008] To solve the above problems, the present invention provides a preparation method of a fluorescence self-warning tactile sensor, including:

[0009] Mix CQDs and N,N-dimethylformamide to obtain a CQDs suspension;

[0010] Mix PVDF and the CQDs suspension to obtain a first mixed solution;

[0011] Mix the first mixed solution with an additive to obtain a PVDF / CQDs mixed solution;

[0012] Adsorb the CQDs suspension in a cellulose porous framework to obtain a first framework;

[0013] Infiltrate the PVDF / CQDs mixture into the first framework to obtain a first functional membrane;

[0014] Assemble the first functional membrane with the ITO-PEN electrode to obtain a fluorescence self-warning tactile sensor.

[0015] On the other hand, preferably, the assembling the first functional membrane with the ITO-PEN electrode to obtain a fluorescence self-warning tactile sensor includes:

[0016] The ITO-PEN electrode includes a first ITO-PEN electrode and a second ITO-PEN electrode;

[0017] Deposit the PVDF / CQDs mixture on the conductive surface of the first ITO-PEN electrode to obtain a first structure;

[0018] Set the first functional membrane on the surface of the first structure away from the conductive surface of the first ITO-PEN electrode to obtain a second structure;

[0019] Deposit the PVDF / CQDs mixture on the first functional membrane of the second structure to obtain a third structure;

[0020] Cover the conductive surface of the second ITO-PEN electrode on the third structure in a staggered manner to obtain a fluorescence self-warning tactile sensor.

[0021] On the other hand, preferably,

[0022] The mixing of CQDs and N,N-dimethylformamide to obtain a CQDs suspension includes:

[0023] Mix CQDs and N,N-dimethylformamide at a mass ratio of 1:(5000 - 10000) and stir for 12 - 24 h; after standing at room temperature for 12 - 24 h, obtain a CQDs suspension;

[0024] The CQDs includes any one of red fluorescent CQDs, orange fluorescent CQDs, yellow fluorescent CQDs, green fluorescent CQDs, cyan fluorescent CQDs, blue fluorescent CQDs, and purple fluorescent CQDs.

[0025] On the other hand, preferably, the mixing of PVDF and the CQDs suspension to obtain a first mixture includes:

[0026] Mix PVDF and the CQDs suspension at a mass ratio of 1:(5 - 15), and stir at a temperature of 60 - 100 °C for 1 - 5 h to obtain a first mixture;

[0027] The PVDF includes any one of PVDF and polyvinylidene fluoride-based polymers.

[0028] On the other hand, preferably,

[0029] Mix the first mixture with an additive to obtain a PVDF / CQDs mixture, including:

[0030] Mix the additive with the first mixture at a mass ratio of 1:(2 - 6), and stir at a temperature of 60 - 100 °C for 1 - 5 h to obtain a PVDF / CQDs mixture;

[0031] The additive includes at least one of ethanol, isopropanol, and ethylene glycol.

[0032] On the other hand, preferably, adsorb the CQDs suspension in a cellulose porous framework to obtain a first framework, including:

[0033] Adsorb the CQDs suspension in a cellulose porous framework and let it stand for 0.5 - 2 h to obtain a first framework;

[0034] The process for the adsorption includes any one of titration, soaking, spin coating, or casting.

[0035] The cellulose porous framework includes any one of filter paper, rice paper, weighing paper, or tissue paper.

[0036] On the other hand, preferably, infiltrate the PVDF / CQDs mixture into the first framework to obtain a first functional membrane, including:

[0037] Infiltrate the PVDF / CQDs mixture into the first framework and let it stand for 0.5 - 2 h;

[0038] Keep it at a temperature of 100 - 130 °C for 0.5 - 2 h to obtain a first functional membrane;

[0039] The process for the infiltration includes any one of spin coating, casting, screen printing, coating, or 3D printing.

[0040] On the other hand, preferably,

[0041] Cover the conductive surface of the second ITO-PEN electrode on the third structure with a dislocation to obtain a fluorescent self-warning tactile sensor, including:

[0042] Cover the conductive surface of the second ITO-PEN electrode on the third structure with a dislocation, and keep it at a temperature of 100 ～ 130 °C for 0.5 - 2 h;

[0043] The leads are fixed to the uncovered parts of the first ITO-PEN electrode and the second ITO-PEN electrode by conductive silver paste, and silicone is coated around for fixation to obtain a fluorescent self-warning tactile sensor.

[0044] In another aspect of the present invention, preferably,

[0045] The process used for the deposition includes any one of spin coating, screen printing, spraying, coating, or 3D printing;

[0046] The thickness of the PVDF / CQDs mixture deposited on the conductive surface of the first ITO-PEN electrode is between 1 and 5 μm;

[0047] The thickness of the PVDF / CQDs mixture deposited on the first functional film of the second structure is between 1 and 5 μm.

[0048] In another aspect of the present invention, preferably, a fluorescent self-warning tactile sensor is obtained by using the preparation method of the fluorescent self-warning tactile sensor as described above. The fluorescent self-warning tactile sensor includes, from bottom to top, a first ITO-PEN electrode, a first composite film, a first functional film, a second composite film, and a second ITO-PEN electrode. The first ITO-PEN electrode and the second ITO-PEN electrode are arranged in a staggered manner. The conductive surface of the first ITO-PEN electrode is connected to the first composite film, and the second composite film is connected to the conductive surface of the second ITO-PEN electrode;

[0049] It further includes a pair of leads, and the pair of leads are respectively arranged on the conductive surfaces of the first ITO-PEN electrode and the second ITO-PEN electrode and are arranged in the staggered part of the first ITO-PEN electrode and the second ITO-PEN electrode.

[0050] (III) Beneficial effects

[0051] The above technical solutions of the present invention have the following beneficial technical effects:

[0052] The sensor prepared by the preparation method of the present invention has the functions of fluorescence self-alarm and piezoelectric effect. The highly dispersed CQDs in the first functional film can sense ultraviolet light in the environment and display it with visual fluorescence. The piezoelectric effect comes from the superposition of the effects of two piezoelectric materials, cellulose and PVDF, which can sense subtle stress changes in the environment and has the characteristic of self-powered. Taking the degradable cellulose paper piezoelectric material as the main component, supplemented by the PVDF piezoelectric material, coupling the "fluorescence effect" and "β-piezoelectric phase induction effect" of CQDs, it has dual functions of piezoelectricity and fluorescence, while maintaining self-function and high flexibility. The cellulose porous framework has a developed porous structure composed of fine fibers in an orderly manner, and also has the characteristics of degradability, mature technology, high industrialization degree, and high cellulose content. The cellulose porous framework provides a framework for the dispersion and adsorption of CQDs. The process of first adsorbing the CQDs suspension on the cellulose porous framework and then infiltrating the PVDF / CQDs mixture makes the CQDs disperse and adsorb on the surface of the cellulose porous framework, forming a fine microstructure. The single quantum state of CQDs can effectively avoid Förster energy transfer, solve the problem of solid-state fluorescence quenching of CQDs, and thus emit colorful fluorescence under ultraviolet light.

[0053] The use of the cellulose porous framework and ITO-PEN electrode of the present invention endows the sensor with high flexibility. The cellulose porous framework has good flexibility and mechanical properties and can serve as a support structure. While maintaining the overall shape of the sensor, it allows it to bend and fold to a certain extent without affecting its performance. The ITO-PEN electrode itself is flexible. After being assembled with the first functional film, the entire sensor has high flexibility, can adapt to surfaces of different shapes, and meet the requirements in various complex environments and application scenarios such as wearable devices. Description of the Drawings

[0054] Figure 1 is the overall process schematic diagram of an embodiment of the present invention;

[0055] Figure 2 is the cross-sectional view of the overall structure of the sensor of an embodiment of the present invention;

[0056] Figure 3 is the SEM morphology diagram of the filter paper of an embodiment of the present invention;

[0057] Figure 4 is the macroscopic photograph of the first framework under 254 nm ultraviolet excitation of an embodiment of the present invention;

[0058] Figure 5 is the macroscopic photograph of the first functional film under 254 nm ultraviolet excitation of an embodiment of the present invention;

[0059] Figure 6It is the output voltage-time curve graph of the sensor according to an embodiment of the present invention;

[0060] Figure 7 It is the output voltage-force curve graph of the sensor according to an embodiment of the present invention;

[0061] Figure 8 It is the output voltage-time curve graph of the sensor for sensing finger bending according to an embodiment of the present invention;

[0062] Figure 9 It is the output voltage-force curve graph of the sensor according to a comparative example of the present invention;

[0063] Reference numerals:

[0064] 1: First ITO-PEN electrode, 2: Second ITO-PEN electrode, 3: First composite film, 4: Second composite film, 5: First functional film. Detailed implementation manners

[0065] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the detailed implementation manners and with reference to the accompanying drawings. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following descriptions, the descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention.

[0066] The structural schematic diagrams according to the embodiments of the present invention are shown in the accompanying drawings. These figures are not drawn to scale, where for the purpose of clarity, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures, as well as their relative sizes and positional relationships, are merely exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0067] Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts fall within the scope of protection of the present invention.

[0068] In the description of the present invention, it should be noted that the terms "first", "second", and "third" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance.

[0069] In addition, the technical features involved in different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0070] The present invention will be described in more detail below with reference to the accompanying drawings. In the various drawings, the same elements are denoted by like reference numerals. For the sake of clarity, the various parts in the drawings are not drawn to scale.

[0071] Embodiment

[0072] A preparation method of a fluorescent self-warning tactile sensor, Figure 1 shows an overall flowchart of an embodiment of the present invention, as Figure 1 shown, including:

[0073] Mix CQDs and N,N-dimethylformamide to obtain a CQDs suspension; CQDs is the abbreviation of Carbon Quantum Dots, which is a nano-scale carbon material with a size below 10 nanometers, having fluorescence characteristics and good water solubility; in this embodiment, CQDs includes any one of red fluorescent CQDs, orange fluorescent CQDs, yellow fluorescent CQDs, green fluorescent CQDs, cyan fluorescent CQDs, blue fluorescent CQDs and purple fluorescent CQDs; the step of obtaining the CQDs suspension includes mixing CQDs and N,N-dimethylformamide at a mass ratio of 1:(5000-10000) and stirring for 12-24 h; after standing at room temperature for 12-24 h, a CQDs suspension is obtained; N,N-dimethylformamide is a polar aprotic solvent with good solubility and dispersibility. In this embodiment, the functions of N,N-dimethylformamide include: N,N-dimethylformamide can effectively disperse CQDs and prevent their aggregation, thus forming a uniform suspension. The polar property of N,N-dimethylformamide helps to stabilize the surface charge of CQDs and prevent its precipitation. N,N-dimethylformamide can form a uniform mixture with PVDF, laying a foundation for the subsequent preparation of the functional film. Stir the mixture for 12-24 hours to ensure that CQDs are fully dispersed in N,N-dimethylformamide. During the stirring process, the functional groups on the surface of CQDs interact with the N,N-dimethylformamide molecules to form a stable suspension. After the stirring is completed, let the suspension stand at room temperature for 12-24 hours. The purpose of standing is to allow the undispersed CQDs particles to precipitate, so as to obtain a uniform CQDs suspension in the supernatant. Here, the CQDs suspension is divided into two parts;

[0074] Mix PVDF and a part of the CQDs suspension to obtain a first mixed solution; PVDF is the abbreviation of polyvinylidene fluoride, which is a high-performance fluoropolymer. In this embodiment, the PVDF includes PVDF and polyvinylidene fluoride-based polymers, and the polyvinylidene fluoride-based polymers include PVDF-HFP or PVDF-TrFE. The step of obtaining the first mixed solution includes mixing PVDF and the CQDs suspension at a mass ratio of 1:(5-15), and stirring at a temperature of 60-100 °C for 1-5 h to obtain the first mixed solution; the purpose of heating is to promote the dissolution of PVDF in DMF and ensure the uniform dispersion of CQDs in the PVDF matrix.

[0075] Mix the first mixed solution with an additive to obtain a PVDF / CQDs mixed solution; mix the first mixed solution with an additive to obtain a PVDF / CQDs mixed solution; mix the additive and the first mixed solution at a mass ratio of 1:(2-6), and stir at a temperature of 60-100 °C for 1-5 h to obtain the PVDF / CQDs mixed solution; the additive includes at least one of ethanol, isopropanol, and ethylene glycol. Ethanol, isopropanol, and ethylene glycol are all polar solvents, which can adjust the polarity of the mixed solution and improve the dispersion of PVDF and CQDs. The introduction of the additive can adjust the evaporation rate of the mixed solution and avoid unevenness or defects on the film surface due to solvent evaporation problems during the film-forming process. The additive can optimize the crystallization behavior of PVDF and improve the mechanical properties and electroactive characteristics of the functional film.

[0076] Adsorb the CQDs suspension in a cellulose porous framework to obtain a first framework; in this embodiment, adsorb the CQDs suspension in a cellulose porous framework and let it stand for 0.5-2 h to obtain the first framework; the adsorption process includes any one of titration, soaking, spin coating, or casting; the cellulose porous framework includes any one of filter paper, rice paper, weighing paper, or tissue paper. The cellulose porous framework has a developed porous structure composed of fine fibers in an orderly manner, and also has characteristics such as biodegradability, mature technology, high industrialization level, and high cellulose content. The cellulose porous framework provides a framework for the dispersed adsorption of CQDs. The process of first adsorbing the CQDs suspension in the cellulose porous framework and then infiltrating the PVDF / CQDs mixed solution makes the CQDs dispersed and adsorbed on the surface of the cellulose porous framework, forming a fine microstructure. Single quantum state CQDs can effectively avoid Förster energy transfer and solve the problem of solid-state fluorescence quenching of CQDs, thus emitting colorful fluorescence under ultraviolet light.

[0077] Infiltrate the PVDF / CQDs mixed solution into the first framework to obtain a first functional film, including:

[0078] Infiltrate the PVDF / CQDs mixed solution into the first framework and let it stand for 0.5 - 2 h; keep it warm at a temperature of 100 - 130 °C for 0.5 - 2 h to obtain the first functional membrane; the infiltration process includes any one of spin coating, casting, screen printing, coating, or 3D printing. By combining the PVDF / CQDs mixed solution with the cellulose framework, a functional membrane with fluorescence characteristics and mechanical properties is formed.

[0079] Assemble the first functional membrane with the ITO-PEN electrode to obtain a fluorescent self-warning tactile sensor, including:

[0080] The ITO-PEN electrode includes a first ITO-PEN electrode and a second ITO-PEN electrode;

[0081] Deposit the PVDF / CQDs mixed solution on the conductive surface of the first ITO-PEN electrode to obtain a first structure; the thickness of the PVDF / CQDs mixed solution deposited on the conductive surface of the first ITO-PEN electrode is between 1 - 5 μm; the deposition process includes any one of spin coating, screen printing, spraying, coating, or 3D printing;

[0082] Set the first functional membrane on the surface of the first structure away from the conductive surface of the first ITO-PEN electrode to obtain a second structure;

[0083] Deposit the PVDF / CQDs mixed solution on the first functional membrane of the second structure to obtain a third structure; the thickness of the PVDF / CQDs mixed solution deposited on the first functional membrane of the second structure is between 1 - 5 μm

[0084] Cover the conductive surface of the second ITO-PEN electrode on the third structure in a staggered manner, and keep it warm at a temperature of 100 ～ 130 °C for 0.5 - 2 h; fix the leads through conductive silver paste at the uncovered parts of the first ITO-PEN electrode and the second ITO-PEN electrode, and coat silicone around for fixation to obtain a fluorescent self-warning tactile sensor.

[0085] A fluorescent self-warning tactile sensor, Figure 2 shows a cross-sectional view of the overall structure of the sensor according to an embodiment of the present invention, as Figure 2As shown, the fluorescent self-warning tactile sensor is obtained by using the preparation method of the fluorescent self-warning tactile sensor as described above. The fluorescent self-warning tactile sensor includes, from bottom to top in sequence, a first ITO-PEN electrode 1, a first composite film 3, a first functional film 5, a second composite film 4, and a second ITO-PEN electrode 2. The first ITO-PEN electrode 1 and the second ITO-PEN electrode 2 are arranged in a staggered manner. The conductive surface of the first ITO-PEN electrode 1 is connected to the first composite film 3, and the second composite film 4 is connected to the conductive surface of the second ITO-PEN electrode 2;

[0086] It further includes a pair of leads. The pair of leads are respectively arranged on the conductive surfaces of the first ITO-PEN electrode 1 and the second ITO-PEN electrode 2, and are arranged in the staggered part of the first ITO-PEN electrode 1 and the second ITO-PEN electrode 2. The first composite film 3 and the second composite film 4 are inserted between the ITO-PEN electrodes and the first functional film 5, which can effectively solve the problem of weak bonding interface caused by the too rough surface of the cellulose porous framework, accelerate the migration and export of charges, and improve the performance of the sensor.

[0087] Example 1

[0088] A preparation method of a fluorescent self-warning tactile sensor includes the following steps:

[0089] Mix red fluorescent CQDs and N,N-dimethylformamide at a mass ratio of 1:10000 and stir for 12 h; then let it stand at room temperature for 12 h to obtain a CQDs suspension;

[0090] Mix PVDF-HFP and a part of the CQDs suspension at a mass ratio of 1:6, stir at 80 °C for 2 h to obtain a first mixed solution; then mix ethanol and the first mixed solution at a mass ratio of 1:3, stir at 80 °C for 2 h to obtain a PVDF / CQDs mixed solution;

[0091] Figure 3 The SEM morphology diagram of the filter paper in an embodiment of the present invention is shown. As Figure 3 shown, the filter paper has a relatively ordered slender cellulose skeleton and a developed pore structure. Titrate another part of the CQDs suspension into the filter paper and let it stand for 30 min to obtain a first framework; Figure 4 The macroscopic photograph of the first framework in an embodiment of the present invention under ultraviolet excitation at 254 nm is shown. As Figure 4 shown, the CQDs diffusely distributed in the first framework can excite excellent red fluorescence; then cast the PVDF / CQDs mixed solution into the first framework and let it stand for 30 min; then keep it at 120 °C for 0.5 h to obtain a first functional film; Figure 5The macroscopic photograph of the first functional film of an embodiment of the present invention under 254 nm ultraviolet excitation is shown. As Figure 5 shown, the first functional film completely inherits the red fluorescence from CQDs and couples the ultraviolet-excited fluorescence self-warning function;

[0092] The PVDF / CQDs mixture is spin-coated on the conductive surface of the first ITO-PEN electrode. Subsequently, the first functional film is stacked on the first composite film 3 with a film thickness of 3 μm; again, the PVDF / CQDs mixture is spin-coated on the first functional film to form another second composite film 4 with a film thickness of 3 μm. Then, the second ITO-PEN electrode is placed with its conductive surface facing down and misaligned to cover its upper surface; after heat preservation at 120 °C for 0.5 h, a fluorescent piezoelectric film is formed between the two symmetric ITO-PEN electrodes. Finally, the uncovered parts of the two electrodes are fixed with lead wires through conductive silver paste, and silicone is coated around for fixation, thus obtaining the fluorescent self-warning tactile sensor.

[0093] Figure 6 The output voltage-time curve graph of the sensor of an embodiment of the present invention is shown. As Figure 6 shown, the sensor of Example 1 can continuously output a stable voltage under a repeated force of 4 N and has the ability of self-power supply; Figure 7 The output voltage-force curve graph of the sensor of an embodiment of the present invention is shown. As Figure 7 shown, there is an excellent proportional relationship between the output voltage and the force of the sensor of Example 1. The corresponding sensitivity and linearity R 2 are 0.194 V / N and 0.992 respectively, Figure 8 The output voltage-time curve graph of the sensor of an embodiment of the present invention for sensing finger bending is shown; as Figure 8 shown, the sensor of Example 1 has high flexibility.

[0094] Example 2

[0095] A preparation method of a fluorescent self-warning tactile sensor includes the following steps:

[0096] Mix orange fluorescent CQDs and N,N-dimethylformamide at a mass ratio of 1:5000 and stir for 24 h; after standing at room temperature for 24 h, a CQDs suspension is obtained;

[0097] Mix PVDF and part of the CQDs suspension at a mass ratio of 1:15 and stir at 100 °C for 5 h to obtain a first mixture; then mix isopropanol and the first mixture at a mass ratio of 1:6 and stir at 100 °C for 5 h to obtain a PVDF / CQDs mixture;

[0098] Soak another part of the CQDs suspension in rice paper and let it stand for 2 h to obtain the first framework; then cast the PVDF / CQDs mixture into the first framework and let it stand for 2 h; then keep it at 130 °C for 2 h to obtain the first functional film;

[0099] Spray the PVDF / CQDs mixture onto the conductive surface of the first ITO-PEN electrode, and then stack the first functional film on top of the first composite film 3 with a film thickness of 5 μm; spray the PVDF / CQDs mixture onto the first functional film again to form another second composite film 4 with a film thickness of 5 μm, then place the second ITO-PEN electrode with its conductive surface facing down and cover it on its upper surface in a misaligned manner; keep it at 130 °C for 2 h to form a fluorescent piezoelectric film between the two symmetric ITO-PEN electrodes. Finally, fix the leads at the uncovered parts of the two electrodes with conductive silver paste and coat the periphery with silica gel for fixation, thus obtaining the fluorescent self-warning tactile sensor.

[0100] Example 3

[0101] A preparation method of a fluorescent self-warning tactile sensor, comprising the following steps:

[0102] Mix blue fluorescent CQDs and N,N-dimethylformamide at a mass ratio of 1:6000 and stir for 15 h; after standing at room temperature for 15 h, obtain the CQDs suspension;

[0103] Mix PVDF-TrFE and a part of the CQDs suspension at a mass ratio of 1:5 and stir at 60 °C for 1 h to obtain the first mixture; then mix isopropanol and the first mixture at a mass ratio of 1:2 and stir at 60 °C for 1 h to obtain the PVDF / CQDs mixture;

[0104] Cast another part of the CQDs suspension onto weighing paper and let it stand for 1 h to obtain the first framework; then cast the PVDF / CQDs mixture into the first framework and let it stand for 1 h; then keep it at 100 °C for 1 h to obtain the first functional film;

[0105] Coat the PVDF / CQDs mixture onto the conductive surface of the first ITO-PEN electrode, and then stack the first functional film on top of the first composite film 3 with a film thickness of 1 μm; coat the PVDF / CQDs mixture onto the first functional film again to form another second composite film 4 with a film thickness of 1 μm, then place the second ITO-PEN electrode with its conductive surface facing down and cover it on its upper surface in a misaligned manner; keep it at 100 °C for 1 h to form a fluorescent piezoelectric film between the two symmetric ITO-PEN electrodes. Finally, fix the leads at the uncovered parts of the two electrodes with conductive silver paste and coat the periphery with silica gel for fixation, thus obtaining the fluorescent self-warning tactile sensor.

[0106] Comparative Example 1

[0107] It is basically the same as Example 1, except that: the fluorescent piezoelectric film is replaced by filter paper, that is, a laminated structure composed of ITO-PEN / filter paper / ITO-PEN. The assembly of the sensor is as follows: stack the filter paper on the conductive surface of the ITO-PEN electrode, and then take another blank ITO-PEN electrode with the conductive surface facing down and cover it on its upper surface in a misaligned manner; keep it at 120 °C for 0.5 h, and finally fix the leads at the uncovered parts of the two electrodes with conductive silver paste, and coat silicone around for fixation, thus obtaining the fluorescent self-warning tactile sensor. Figure 9 The output voltage-force curve of the sensor of a comparative example of the present invention is shown, as Figure 9 shown, the sensitivity and linearity R of Comparative Example 1 2 The corresponding values are 0.113 V / N and 0.987 respectively, which are much lower than those of the sensor in Example 1.

[0108] It should be understood that the above specific embodiments of the present invention are only used for exemplary illustration or explanation of the principle of the present invention, and do not constitute a limitation to the present invention. Therefore, any modifications, equivalent replacements, improvements, etc. made without departing from the spirit and scope of the present invention shall be included within the protection scope of the present invention. In addition, the appended claims of the present invention are intended to cover all changes and modifications that fall within the scope and boundaries of the appended claims, or equivalent forms of such scope and boundaries.

[0109] In the above description, technical details such as the layout and etching of each layer are not described in detail. However, those skilled in the art should understand that various means in the prior art can be used to form layers, regions, etc. with the required shapes. In addition, in order to form the same structure, those skilled in the art can also design methods that are not exactly the same as the methods described above.

[0110] The present invention has been described above with reference to the embodiments of the present invention. However, these embodiments are only for the purpose of illustration, and not for the purpose of limiting the scope of the present invention. The scope of the present invention is defined by the appended claims and their equivalents. Without departing from the scope of the present invention, those skilled in the art can make various substitutions and modifications, and these substitutions and modifications should all fall within the scope of the present invention.

[0111] Although the embodiments of the present invention have been described in detail, it should be understood that various changes, substitutions and alterations can be made to the embodiments of the present invention without departing from the spirit and scope of the present invention.

[0112] Obviously, the above embodiments are merely examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. And the obvious changes or modifications derived therefrom still fall within the protection scope of the present invention.

Claims

1. A preparation method of a fluorescent self-warning tactile sensor, characterized in that Including: Mix CQDs and N,N-dimethylformamide to obtain a CQDs suspension; Mix PVDF and the CQDs suspension to obtain a first mixture; Mix the first mixture with an additive to obtain a PVDF / CQDs mixture; Adsorb the CQDs suspension in a cellulose porous framework to obtain a first framework; Infiltrate the PVDF / CQDs mixture into the first framework to obtain a first functional membrane; Assemble the first functional membrane with an ITO-PEN electrode to obtain a fluorescent self-warning tactile sensor.

2. The preparation method according to claim 1, characterized in that, The assembling the first functional membrane with the ITO-PEN electrode to obtain a fluorescent self-warning tactile sensor includes: The ITO-PEN electrode includes a first ITO-PEN electrode and a second ITO-PEN electrode; Deposit the PVDF / CQDs mixture on the conductive surface of the first ITO-PEN electrode to obtain a first structure; Set the first functional membrane on the surface of the first structure away from the conductive surface of the first ITO-PEN electrode to obtain a second structure; Deposit the PVDF / CQDs mixture on the first functional membrane of the second structure to obtain a third structure; Cover the conductive surface of the second ITO-PEN electrode on the third structure in a misaligned manner to obtain a fluorescent self-warning tactile sensor.

3. The preparation method according to claim 1, characterized in that The mixing CQDs and N,N-dimethylformamide to obtain a CQDs suspension includes: Mix CQDs and N,N-dimethylformamide at a mass ratio of 1:(5000 - 10000) and stir for 12 - 24 h; after standing at room temperature for 12 - 24 h, obtain a CQDs suspension; The CQDs includes any one of red fluorescent CQDs, orange fluorescent CQDs, yellow fluorescent CQDs, green fluorescent CQDs, cyan fluorescent CQDs, blue fluorescent CQDs and purple fluorescent CQDs.

4. The preparation method according to claim 1, characterized in that, The mixing PVDF and the CQDs suspension to obtain a first mixture includes: Mix PVDF and the CQDs suspension at a mass ratio of 1:(5 - 15), stir at a temperature of 60 - 100 °C for 1 - 5 h to obtain a first mixture; The PVDF includes any one of PVDF and polyvinylidene fluoride-based polymers.

5. The preparation method according to claim 1, characterized in that, Mixing the first mixture with an additive to obtain a PVDF / CQDs mixture includes: Mix the additive and the first mixture at a mass ratio of 1:(2 - 6), stir at a temperature of 60 - 100 °C for 1 - 5 h to obtain a PVDF / CQDs mixture; The additive includes at least one of ethanol, isopropanol and ethylene glycol.

6. The preparation method according to claim 1, characterized in that The adsorbing the CQDs suspension in a cellulose porous framework to obtain a first framework includes: Adsorb the CQDs suspension in a cellulose porous framework, stand for 0.5 - 2 h to obtain a first framework; The process adopted for the adsorption includes any one of titration, soaking, spin coating or casting. The cellulose porous framework includes any one of filter paper, rice paper, weighing paper or facial tissue.

7. The preparation method according to claim 1, wherein Infiltrating the PVDF / CQDs mixture into the first framework to obtain the first functional film includes: Infiltrating the PVDF / CQDs mixture into the first framework and standing for 0.5 - 2 h; Keeping warm at a temperature of 100 - 130 °C for 0.5 - 2 h to obtain the first functional film; The process used for the infiltration includes any one of spin coating, casting, screen printing, coating or 3D printing.

8. The preparation method according to claim 2, wherein Covering the conductive surface of the second ITO-PEN electrode on the third structure with dislocation to obtain the fluorescent self-warning tactile sensor includes: Cover the conductive surface of the second ITO-PEN electrode on the third structure with a dislocation, and keep it at a temperature of 100 ～ 130 °C for 0.5 to 2 h; Fixing leads through conductive silver paste at the uncovered parts of the first ITO-PEN electrode and the second ITO-PEN electrode, and coating silica gel around for fixation to obtain the fluorescent self-warning tactile sensor.

9. The preparation method according to claim 2, wherein The process used for the deposition includes any one of spin coating, screen printing, spraying, coating or 3D printing; The thickness of the PVDF / CQDs mixture deposited on the conductive surface of the first ITO-PEN electrode is between 1 - 5 μm; The thickness of the PVDF / CQDs mixture deposited on the first functional film of the second structure is between 1 - 5 μm.

10. A fluorescent self-warning tactile sensor, characterized in that, The fluorescent self-warning tactile sensor is prepared by using the preparation method of the fluorescent self-warning tactile sensor according to any one of claims 1 - 9; The fluorescent self-warning tactile sensor includes: from bottom to top, it successively includes a first ITO-PEN electrode (1), a first composite film (3), a first functional film (5), a second composite film (4) and a second ITO-PEN electrode (2). The first ITO-PEN electrode (1) and the second ITO-PEN electrode (2) are arranged with dislocation. The conductive surface of the first ITO-PEN electrode (1) is connected to the first composite film (3), and the second composite film (4) is connected to the conductive surface of the second ITO-PEN electrode (2); It further includes a pair of leads, and the pair of leads are respectively arranged on the conductive surfaces of the first ITO-PEN electrode (1) and the second ITO-PEN electrode (2), and are arranged at the dislocated part of the first ITO-PEN electrode (1) and the second ITO-PEN electrode (2).

Images