Carbon dot antibacterial insole and manufacturing method thereof

Abstract

The invention relates to the technical field of insole manufacturing, in particular to a carbon dot antibacterial insole and a manufacturing method thereof. Preparing a CNT / ACET / PDMS pressure sensor; preparing a piezoelectric energy layer; preparing an N, S-CDs optical antibacterial layer; preparing a PDMS (Polydimethylsiloxane) matrix; the CNT / ACET / PDMS pressure sensor and the N, S-CDs optical antibacterial layer are assembled on the PDMS substrate in a layered mode, and a PDMS assembly is obtained; compounding a piezoelectric energy layer with the assembled PDMS component; and covering the surface with a PI / PDMS packaging layer to obtain the carbon dot antibacterial insole. The CNT / ACET / PDMS pressure sensor can detect pressure, the piezoelectric energy layer can be self-powered, and the N, S-CDs optical antibacterial layer utilizes carbon dots in the N, S-CDs optical antibacterial layer to realize efficient antibacterial ability. The stability and durability of the insole in a daily wearing scene are ensured through the flexible adaptation of the PDMS matrix and the protection effect and permeation sterilization effect of the PI / PDMS packaging layer.

Description

Technical Field

[0001] This application relates to the field of insole manufacturing technology, and mainly to a carbon dot antibacterial insole and its manufacturing method. Background Technology

[0002] The current smart insole industry suffers from key issues such as limited functionality, insufficient durability, limited antibacterial effects, and reliance on external power. Traditional insoles mostly offer only basic cushioning; while a few smart models integrate pressure sensors, uneven sensor distribution and rigid circuit connections often result in low pressure monitoring accuracy, and signal interruptions are common after repeated wear and bending. Regarding antibacterial properties, existing products mostly use silver ion coatings or ordinary antibacterial fibers. The former poses a risk of skin irritation, while the latter generally has an antibacterial rate below 80%, and its performance degrades by more than 50% after three washes, failing to address the challenges of consistently damp feet that breed bacteria. These insoles cannot meet the long-term, stable functional requirements of sports and health, and medical rehabilitation applications.

[0003] Therefore, existing technologies still need to be improved and developed. Summary of the Invention

[0004] In view of the shortcomings of the prior art, the purpose of this application is to provide a carbon dot antibacterial insole and its manufacturing method, which aims to solve the problem that existing ordinary insoles cannot meet the requirements of long-term sterilization.

[0005] The technical solution of this application is as follows: In a first aspect, this application provides a method for manufacturing a carbon dot antibacterial insole, comprising the following steps: Fabrication of CNT / ACET / PDMS pressure sensors; Fabrication of piezoelectric energy layers; Preparation of N,S-CDs photo-antibacterial layer; Preparation of PDMS matrix; The CNT / ACET / PDMS pressure sensor and the N,S-CDs photo-antibacterial layer are layered and assembled on the PDMS substrate to obtain a PDMS component. The piezoelectric energy layer is combined with the assembled PDMS component; The surface is covered with a PI / PDMS encapsulation layer to obtain the carbon dot antibacterial insole.

[0006] Furthermore, the step of fabricating the CNT / ACET / PDMS pressure sensor includes: Carbon nanotubes were added to ethyl acrylate and dispersed to obtain a dispersion. The polydimethylsiloxane prepolymer was mixed with Sylgard184 curing agent, added to the dispersion, stirred and degassed, poured into a mold and cured, and then connected to a copper electrode.

[0007] Furthermore, the step of preparing the piezoelectric energy layer includes: Configure a PVDF film by cutting the PVDF film into circular units and laying them in an array on a copper foil electrode; A graphene coating solution is coated onto the surface of the copper foil electrode and then dried. The PVDF film has a thickness of 0.2 mm, the circular unit has a radius of 0.5-0.8 cm, and the array spacing is 0.8-1 cm. The graphene coating solution contains 1.5% graphene by mass, and the coating amount is 0.05-0.1 mg / cm³. 2 The drying temperature is 60-80℃.

[0008] Furthermore, the step of preparing the N,S-CDs photo-antibacterial layer includes: Citric acid and cysteine ​​were dissolved in deionized water to obtain a precursor solution; After microwave heating and cooling, centrifugation, filtration through a filter membrane, dialyzing, freezing, and vacuum sublimation drying, N,S-CDs powder was obtained and dispersed in deionized water to obtain N,S-CDs solution. Polyacrylic acid was dissolved in deionized water to obtain a polyacrylic acid solution, which was then mixed with a graphene oxide solution, and finally the N,S-CDs solution was added to obtain a mixture. After the mixture is shaped, it is immersed in a calcium chloride solution for crosslinking, then washed and dried.

[0009] Furthermore, the mass ratio of citric acid to cysteine ​​is 2:1, and the total mass of citric acid and cysteine ​​accounts for 6-7% of the mass of the precursor solution. The microwave heating is performed in an 800W microwave oven for 3 minutes; the centrifugation speed is 5000-7000 rpm for 2 minutes; the pore size of the filter membrane is 0.22 μm; the dialysis time is 24 hours; the freezing temperature is -50~-80℃ for 12 hours; and the vacuum sublimation drying is performed at a vacuum degree of 1-10 Pa for 36-48 hours. The polyacrylic acid solution has a mass concentration of 10% and the graphene oxide solution has a concentration of 2 mg / mL, with a ratio of 10 ml to 100 g. The concentration of the N,S-CDs solution is 0.02 g / mL, and the ratio of the N,S-CDs solution to the polyacrylic acid solution is 10 ml: 100 g. The concentration of the calcium chloride solution is 2 mg / mL, the crosslinking time is 24 hours, and the drying temperature after washing is 40-50℃ for 24 hours. The thickness of the N,S-CDs photo-antibacterial layer is 0.3-0.5 cm.

[0010] Furthermore, the step of preparing the PDMS matrix includes: Using commercially available sugar cubes as a water-soluble template, the sample was immersed in a mixed solution of PDMS prepolymer and curing agent; Place in the mold and cure at 100℃ for 1 hour; After removing the sugar cubes, immerse them in 60℃ deionized water for 2 hours to dissolve them. The mass ratio of the PDMS prepolymer to the curing agent is 15:1, and the thickness of the mold is 2cm.

[0011] Furthermore, the layered assembly step includes: The PDMS substrate is cut into the shape of an insole; Multiple CNT / ACET / PDMS pressure sensors are embedded into the surface of the PDMS substrate in sections for the forefoot, midfoot, and heel areas. After bonding to the printed circuit board, a 0.2cm thick PDMS coating is applied; The signal acquisition and transmission module, energy management module, and intelligent control module are embedded in the area near the heel of the bottom center of the PDMS substrate. Connect the printed circuit board via wire through-holes; The ultraviolet LED is connected to the energy management module by passing a wire through a hole in the side of the PDMS substrate; The N,S-CDs photo-antibacterial layer is then applied to the surface of the PDMS substrate.

[0012] Furthermore, the layered assembly also includes the fabrication of a flexible interconnect structure, comprising the following steps: The anisotropic conductive film is cut to the shape of an insole and pre-attached to the bottom surface of the CNT / ACET / PDMS pressure sensor electrode, and then hot-pressed at 150°C and 8MPa for 60 seconds.

[0013] Furthermore, the compounding step includes: The piezoelectric energy layer was placed in a mold, PDMS was added to control the thickness to 0.5 cm, and it was semi-cured at 100°C for 0.5 hours. After connecting the PDMS component to the energy management module via wires, place it above the piezoelectric energy layer, cover the piezoelectric energy layer with a PI layer, and semi-cur the whole at 100°C for 0.5 hours. The step of covering the surface with a PI / PDMS encapsulation layer includes: An uncured PI / PDMS film was placed over the surface of the N,S-CDs photo-antibacterial layer, hot-pressed at 80°C for 5 minutes, and then cured at 150°C for 2 hours.

[0014] Secondly, this application provides a carbon dot antibacterial insole, which is prepared by the carbon dot antibacterial insole manufacturing method described in the first aspect.

[0015] Beneficial Effects: In this application, core functional layers such as the CNT / ACET / PDMS pressure sensor, piezoelectric energy layer, and N,S-CDs photo-antibacterial layer are prepared stepwise, and layered assembly and composite encapsulation are achieved based on the PDMS substrate, forming an insole integrating sensing, power supply, and antibacterial functions. The CNT / ACET / PDMS pressure sensor can detect pressure, the piezoelectric energy layer is self-powered, and the N,S-CDs photo-antibacterial layer utilizes its carbon dots to achieve highly efficient antibacterial capabilities. Through the flexible adaptation of the PDMS substrate and the protective effect of the PI / PDMS encapsulation layer, the stability and durability of the insole are ensured in daily wear scenarios. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the structure of the carbon dot antibacterial insole of this application.

[0017] Figure 2 This is a schematic diagram of the layered structure of the PI / PDMS encapsulation layer, N,S-CDs photo-antibacterial layer and PDMS substrate in this application.

[0018] Figure 3 This is a schematic diagram of the structure of the N,S-CDs photo-antibacterial layer of this application. Detailed Implementation

[0019] This application provides a carbon dot antibacterial insole and a method for manufacturing the same. To make the objectives, technical solutions, and effects of this application clearer and more explicit, the following provides a more detailed description. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0020] Reference Figures 1-3 This application provides a method for manufacturing a carbon dot antibacterial insole, which includes the following steps: S1. Fabrication of CNT / ACET / PDMS pressure sensor; S2. Fabrication of a piezoelectric energy layer; S3. Prepare N,S-CDs photo-antibacterial layer; S4. Preparation of PDMS matrix; S5. Assemble the CNT / ACET / PDMS pressure sensor and N,S-CDs photo-antibacterial layer on the PDMS substrate to obtain the PDMS component; S6. Composite the piezoelectric energy layer with the assembled PDMS component; S7. The surface is covered with a PI / PDMS encapsulation layer to obtain a carbon dot antibacterial insole.

[0021] In this application, core functional layers such as a CNT / ACET / PDMS pressure sensor, a piezoelectric energy layer, and an N,S-CDs photo-antibacterial layer are fabricated in stages. These layers are then assembled and encapsulated using a PDMS substrate to form an insole integrating sensing, power supply, and antibacterial functions. The CNT / ACET / PDMS pressure sensor detects pressure, the piezoelectric energy layer is self-powered, and the N,S-CDs photo-antibacterial layer utilizes carbon dots to achieve highly efficient antibacterial capabilities. The flexible fit of the PDMS substrate and the protective and penetrating bactericidal effects of the PI / PDMS encapsulation layer ensure the stability and durability of the insole in everyday wear scenarios.

[0022] Further, in step S1, the step of fabricating the CNT / ACET / PDMS pressure sensor includes: S11. Carbon nanotubes are added to ethyl acrylate and dispersed to obtain a dispersion. S12. Mix the polydimethylsiloxane prepolymer with Sylgard184 curing agent, add it to the dispersion, stir to degas, pour it into a mold and cure it, connect the copper electrode to obtain the CNT / ACET / PDMS pressure sensor.

[0023] The dispersion is carried out by ultrasonic dispersion for 1-2 hours, and the mass ratio of polydimethylsiloxane prepolymer to Sylgard184 curing agent is 10:1; after pouring into the mold, the curing temperature is 60-80℃ and the time is 1-2 hours.

[0024] In this application, carbon nanotubes (CNTs) are dispersed in ethyl acrylate (ACET) and then composited with PDMS prepolymer, followed by curing and electrode connection to form a sensor. This ensures that the CNTs are uniformly distributed within the PDMS matrix, guaranteeing the linearity and sensitivity of the sensor within the plantar pressure range. It can accurately capture pressure differences in the forefoot, midfoot, and heel areas, providing reliable data support for gait analysis and foot health monitoring. Simultaneously, the flexibility and elasticity of PDMS material ensure the cyclic performance of the CNT / ACET / PDMS pressure sensor.

[0025] Further, in step S2, the step of preparing the piezoelectric energy layer includes: S21. Prepare a PVDF film by cutting the PVDF film into circular units and laying them in an array on a copper foil electrode. S22. Coat the surface of the copper foil electrode with graphene coating liquid and dry to obtain a piezoelectric energy layer.

[0026] In this application, by cutting PVDF films into circular units and arraying them on copper foil electrodes, the utilization of the area affected by foot pressure can be maximized, enabling the mechanical energy of walking and standing to be converted into electrical energy more efficiently. By coating the surface of the copper foil electrodes with a graphene coating liquid, the high conductivity of graphene can reduce the electrode contact resistance and reduce losses during the energy conversion process.

[0027] In step S2, when preparing the piezoelectric energy layer, a specific size (radius 0.5-0.8cm) with a thickness of 0.2mm is used. At the same time, a graphene coating liquid with a mass ratio of 1.5% and a coating amount of 0.05-0.1mg / cm² is coated on the surface of the copper foil electrode. The high conductivity of graphene can reduce the electrode contact resistance and reduce the loss in the energy conversion process. The drying temperature of 60-80℃ can ensure the stable adhesion of the graphene coating layer and avoid the damage of high temperature to the piezoelectric properties of PVDF. Ultimately, the piezoelectric energy layer can continuously power the pressure sensor, ultraviolet LED and other modules, realize the self-powering of the insole, get rid of the dependence on external power source and improve the convenience of product use.

[0028] Furthermore, in step S21, the thickness of the PVDF film is 0.2 mm, the radius of the circular unit is 0.5-0.8 cm, and the spacing of the array is 0.8-1 cm.

[0029] In this application, by cutting and arranging the array according to specific parameters, sufficient flexibility is achieved to conform to the plantar curve while ensuring piezoelectric conversion efficiency. This matches the pressure sensing needs of different areas of the plantar surface, avoiding insufficient monitoring accuracy due to overly large units or energy waste caused by overly small units. The array spacing ensures that the units do not interfere with each other while achieving sufficient pressure monitoring coverage, thus optimizing the balance between piezoelectric energy conversion efficiency and pressure monitoring.

[0030] Furthermore, in step S22, the graphene content in the graphene coating solution is 1.5% by mass, the coating amount is 0.05-0.1 mg / cm2, and the drying temperature is 60-80℃.

[0031] The solvent in the graphene coating solution is ethanol.

[0032] By controlling the concentration of the graphene coating solution, graphene agglomeration can be avoided while ensuring conductivity, thus guaranteeing the uniformity of the coating layer. An appropriate coating amount can form an ultra-thin and dense conductive layer on the copper foil surface, reducing resistance without increasing the thickness of the energy layer, thus avoiding impacting insole comfort. A suitable drying temperature can quickly remove the solvent from the coating solution while preventing a decrease in the piezoelectric coefficient of the PVDF film due to high temperatures, ensuring the long-term stable operation of the piezoelectric energy layer.

[0033] Further, in step S3, the step of preparing the N,S-CDs photo-antibacterial layer includes: S31. Citric acid and cysteine ​​are dissolved in deionized water to obtain a precursor solution; S32. After microwave heating and cooling, centrifugation, filtration through a filter membrane, dialyzing, freezing and vacuum sublimation drying are performed to obtain N,S-CDs powder, which is then dispersed in deionized water to obtain an N,S-CDs solution. S33. Polyacrylic acid is dissolved in deionized water to obtain a polyacrylic acid solution, graphene oxide solution is added and mixed, and then N,S-CDs solution is added and mixed to obtain a mixture. S34. After the mixture is shaped, it is immersed in calcium chloride solution for cross-linking, washed and dried to obtain N,S-CDs photo-antibacterial layer.

[0034] The solvents for both the graphene oxide solution and the N,S-CDs solution are deionized water.

[0035] In this application, high-purity N,S-CDs powder can be prepared through the above steps. This process effectively removes precursor residues and small molecule impurities, ensuring the purity of N,S-CDs and guaranteeing their high efficiency in exerting their antibacterial effect. Subsequently, N,S-CDs are composited with graphene oxide and polyacrylic acid and cross-linked with calcium chloride. Graphene oxide not only enhances the mechanical strength and toughness of the film, resisting friction and pressure during daily wear, but also forms a synergistic antibacterial effect with N,S-CDs, inhibiting bacterial growth through a dual mechanism of physical barrier and chemical sterilization. The porous structure of polyacrylic acid gives the antibacterial layer good breathability and sweat absorption, keeping feet dry and reducing the environment for bacterial growth. The calcium chloride cross-linking treatment enhances the durability of the film, ensuring that the antibacterial performance remains stable after multiple washes, which helps to alleviate the problem of easy decay of the antibacterial effect of traditional antibacterial insoles.

[0036] Furthermore, in step S31, the mass ratio of citric acid to cysteine ​​is 2:1, and the total mass of citric acid and cysteine ​​accounts for 6-7% of the mass of the precursor solution.

[0037] In this application, a suitable ratio facilitates the formation of uniformly co-doped N,S-CDs from the precursor reaction, balancing the content of carbon source and dopant elements. This avoids insufficient cysteine ​​leading to excessively low doping levels and weakened antibacterial properties, or excessive cysteine ​​causing carbon dot aggregation. The citric acid mass ratio controls the concentration of the precursor solution, ensuring sufficient carbonization to form carbon dots during microwave heating while avoiding excessively high concentrations that could lead to overly vigorous reactions and uneven carbon dot particle size, thus ensuring the antibacterial activity and dispersibility of N,S-CDs.

[0038] Further, in step S32, microwave heating is performed using an 800W microwave oven for 3 minutes, centrifugation is performed at a speed of 5000-7000 rpm for 2 minutes, the pore size of the filter membrane is 0.22 μm, the dialysis time is 24 hours, the freezing temperature is -50~-80℃ for 12 hours, and the vacuum degree of vacuum sublimation drying is 1-10 Pa for 36-48 hours.

[0039] In this application, the degree of carbonization is controlled by adjusting the preparation parameters to avoid insufficient carbonization and low carbon dot formation due to excessively low power, or excessive carbon dot carbonization and loss of antibacterial activity due to excessively high power. Centrifugation followed by filtration effectively removes unreacted large particulate impurities, while dialysis further removes small molecule residues, ensuring the purity of N,S-CDs. Freezing and vacuum sublimation drying can achieve carbon dot drying at low temperatures, avoiding the destruction of carbon dot structure caused by high-temperature drying and ensuring its photothermal antibacterial properties.

[0040] Further, in step S33, the mass concentration of polyacrylic acid in the polyacrylic acid solution is 10%, the concentration of graphene oxide solution is 2 mg / mL, and the ratio of graphene oxide solution to polyacrylic acid solution is 10 ml: 100 g. The concentration of the N,S-CDs solution was 0.02 g / mL, and the ratio of it to the polyacrylic acid solution was 10 mL: 100 g.

[0041] In this application, the appropriate concentration of the polyacrylic acid solution ensures the viscosity required for film formation while providing sufficient porous structure to guarantee breathability. The ratio of graphene oxide to N,S-CDs can improve the mechanical properties of the film while ensuring the effective concentration of antibacterial components, avoiding excessive graphene oxide leading to an overly stiff film that affects comfort, or insufficient N,S-CDs resulting in poor antibacterial effect, thus balancing mechanical and antibacterial properties.

[0042] Furthermore, in step S34, the concentration of the calcium chloride solution is 2 mg / mL, the crosslinking time is 24 hours, and the drying temperature after washing is 40-50℃ for 24 hours. The thickness of the N,S-CDs photo-antibacterial layer is 0.3-0.5cm.

[0043] In this application, calcium chloride can crosslink with polyacrylic acid to form a stable three-dimensional network structure, enhancing the film's wash resistance and mechanical strength. Drying allows for the slow removal of moisture from the film, preventing cracking or deformation caused by rapid drying. Simultaneously, by controlling the appropriate curvature, sufficient antibacterial content in the antibacterial layer can be ensured while avoiding excessive thickness that could negatively impact the overall comfort and fit of the insole, thus balancing antibacterial effectiveness with wearing experience.

[0044] Further, in step S4, the step of preparing the PDMS matrix includes: S41. Using commercially available sugar cubes as a water-soluble template, immerse them in a mixed solution of PDMS prepolymer and curing agent; S42. Place in the mold and cure at 100℃ for 1 hour; S43. After removing the sugar cubes, immerse them in 60℃ deionized water for 2 hours to dissolve them.

[0045] In this application, a PDMS matrix with uniform pores can be quickly formed by a template method. The porous structure can not only improve the breathability and moisture absorption of the insole and reduce the stuffiness of the feet, but also reduce the weight of the matrix and improve the lightness of wearing.

[0046] Furthermore, in step S4, the mass ratio of PDMS prepolymer to curing agent is 15:1, and the thickness of the mold is 2cm.

[0047] In this application, PDMS prepolymer is fully cured to provide sufficient flexibility and elasticity, allowing it to conform to the foot's curves and cushion the impact of walking, thus improving wearing comfort. The 2cm mold thickness matches the thickness requirements of everyday insoles, avoiding excessive thickness or thinness that could negatively impact the user experience.

[0048] Furthermore, in step S5, the layered assembly step includes: S51. Cut the PDMS substrate into the shape of an insole; S52. Multiple CNT / ACET / PDMS pressure sensors are embedded into the surface of the PDMS substrate in sections for the forefoot area, midfoot area, and heel area. S53, after bonding the printed circuit board, coat it with 0.2cm thick PDMS; S54. Embed the signal acquisition and transmission module, energy management module, and intelligent control module into the area near the heel of the bottom center of the PDMS substrate. S55, Connect the printed circuit board via wire through-hole; S56. Connect the ultraviolet LED to the energy management module by passing wires through the perforations on the side of the PDMS substrate; S57. Next, cover the surface of the PDMS substrate with the N,S-CDs photo-antibacterial layer.

[0049] The number of CNT / ACET / PDMS pressure sensors can be set to 20-24 or other quantities, depending on the actual manufacturing process.

[0050] In this application, the CNT / ACET / PDMS pressure sensors are embedded into the PDMS substrate in layers according to the foot region. This ensures that the sensors accurately correspond to key pressure areas on the foot, improving the targeting and accuracy of pressure monitoring. Coating the printed circuit board with PDMS after bonding it not only fixes the relative position of the circuit board and the sensor but also prevents short circuits due to the insulation of PDMS. The signal acquisition and transmission module, energy management module, and intelligent control module are embedded in the bottom of the PDMS substrate near the heel. This area is less affected by pressure during wear, reducing damage to the modules caused by compression, and facilitating wire connections between the modules, sensors, and piezoelectric energy layer. The ultraviolet LED is connected to the energy management module through side perforations, ensuring that the LED surrounds the N,S-CDs photo-antibacterial layer. This allows for uniform ultraviolet light irradiation of the antibacterial layer, maximizing the activation of the N,S-CDs photo-antibacterial effect and improving antibacterial efficiency.

[0051] Furthermore, in step S5, the layered assembly also includes the fabrication of flexible interconnect structures, comprising the following steps: S50. Cut the anisotropic conductive film to the shape of an insole, pre-attach it to the bottom surface of the CNT / ACET / PDMS pressure sensor electrode, and bond it by hot pressing at 150℃ and 8MPa for 60 seconds.

[0052] In this application, by pre-attaching anisotropic conductive film (ACF) to the bottom surface of the sensor electrode and hot-pressing it, vertical conduction (Z-axis resistance < 0.1Ω) and horizontal insulation (XY-axis resistance > 10¹²Ω) between the sensor and the printed circuit board can be achieved. This interconnection method not only ensures the stability and low loss of electrical signal transmission, but also avoids the problem of wire breakage caused by traditional rigid welding when the insole is bent, thanks to the flexible characteristics of ACF. This significantly improves the reliability and durability of the insole circuit connection and is suitable for bending and squeezing scenarios in daily wear.

[0053] Further, in step S6, the compounding step includes: S61. Place the piezoelectric energy layer into the mold, add PDMS to control the thickness to 0.5cm, and semi-cur at 100℃ for 0.5 hours; S62. After connecting the PDMS component to the energy management module via wires, place it above the piezoelectric energy layer, cover the piezoelectric energy layer below it, and semi-cur the whole thing at 100°C for 0.5 hours.

[0054] In this application, the piezoelectric energy layer is first semi-cured and shaped using PDMS, and then bonded to the PDMS module before being semi-cured as a whole. This composite process ensures a tight bond between the piezoelectric energy layer and the PDMS module, reducing energy loss and structural loosening caused by interlayer gaps. A PI layer covers the piezoelectric energy layer. PI material possesses excellent high-temperature resistance, aging resistance, and insulation properties, protecting the piezoelectric energy layer from external environmental corrosion (such as sweat and dust) and extending its service life.

[0055] Further, in step S7, the step of covering the surface with a PI / PDMS encapsulation layer includes: S71. Cover the surface of the N,S-CDs photo-antibacterial layer with the uncured PI / PDMS film, hot press at 80℃ for 5 minutes, and then cure at 150℃ for 2 hours.

[0056] In this application, an uncured PI / PDMS film is hot-pressed and then cured at high temperature with an N,S-CDs photo-antibacterial layer. This ensures a tight bond between the PI / PDMS encapsulation layer and the antibacterial layer, preventing interlayer delamination. The protective properties of the PI material effectively protect the underlying composite structure layer, as well as the internal circuitry and functional layers. Simultaneously, the abrasion resistance of PI enhances the wear resistance of the insole surface, extending the overall lifespan of the insole. The PDMS used in the mixture has a certain degree of breathability, allowing moisture and gases to permeate through the PI / PDMS film, ensuring a bactericidal effect on the foot environment.

[0057] This application also provides a carbon dot antibacterial insole, which is prepared by the carbon dot antibacterial insole manufacturing method described above.

[0058] The insoles manufactured using the provided method feature plantar pressure monitoring capabilities, providing real-time feedback on gait and foot pressure distribution, thus offering data support for foot health management. They are also self-powered by a piezoelectric energy layer, eliminating the need for frequent battery replacements and significantly improving ease of use. Simultaneously, the N,S-CDs photo-antibacterial layer, in synergy with ultraviolet LEDs, ensures a high kill rate against common pathogens, and its antibacterial performance remains stable even after multiple washes, effectively solving the problems of bacterial growth and odor in traditional insoles. Furthermore, the insoles are made entirely of flexible materials, conforming to the curves of the foot for comfortable wear. The protective functions of the PI / PDMS encapsulation layer and PDMS substrate further ensure the stability and durability of the insoles during long-term use, making them suitable for various scenarios such as sports and health, medical rehabilitation, and daily foot care.

[0059] The following specific examples provide further details.

[0060] Example 1 This embodiment 1 provides a method for manufacturing carbon dot antibacterial insoles, the specific steps of which are as follows: (1) Preparation of CNT / ACET / PDMS pressure sensor (step S1).

[0061] S11: Weigh 0.5g of multi-walled carbon nanotubes (diameter 10-15nm, length 5-10μm), add them to 50mL of ethyl acrylate (analytical grade), and sonicate them for 1.5 hours using an ultrasonic instrument with a power of 300W to form a uniform and stable CNT / ACET dispersion. S12: Weigh polydimethylsiloxane (PDMS) prepolymer (viscosity 5000 cP) and Sylgard 184 curing agent at a mass ratio of 10:1, mix and stir for 10 minutes until uniform; add all of the above CNT / ACET dispersion to the PDMS mixture, continue stirring for 20 minutes, then place in a vacuum drying oven (vacuum degree -0.095 MPa) for 15 minutes to remove air bubbles; pour the degassed mixture into a polytetrafluoroethylene mold with dimensions of 10cm×25cm×0.3cm, place in an oven and cure at 70℃ for 1.5 hours; after curing, remove and cut into 22 circular sensor units with a diameter of 0.8cm, weld a copper electrode with a thickness of 0.1mm to the surface of each unit to obtain the CNT / ACET / PDMS pressure sensor.

[0062] (2) Prepare the piezoelectric energy layer (step S2).

[0063] S21: Select a 0.2mm thick polyvinylidene fluoride (PVDF) piezoelectric film (piezoelectric coefficient d33=30pC / N), and cut it into circular units with a radius of 0.6cm using a laser cutter; cut the copper foil electrode (0.05mm thick) into a size of 12cm×27cm, and attach the PVDF circular units to the surface of the copper foil electrode in a honeycomb array at a spacing of 0.9cm, ensuring that each unit is tightly attached to the copper foil; S22: Preparation of graphene coating solution: Weigh 0.15g of graphene powder (3-5 layers, 1-5μm diameter), add it to 9.85g of anhydrous ethanol, and ultrasonically disperse for 30 minutes to form a graphene-ethanol dispersion with a mass ratio of 1.5%; use a doctor blade coating method to uniformly coat the coating solution on the surface of the copper foil electrode (non-PVDF unit area), and control the coating amount to 0.08mg / cm²; place the coated copper foil in a 65℃ oven to dry for 2 hours, and cool to room temperature to obtain the piezoelectric energy layer.

[0064] (3) Prepare N,S-CDs photo-antibacterial layer (step S3).

[0065] S31: Weigh 1g of citric acid (analytical grade) and 0.5g of cysteine ​​(analytical grade), add them together to 21mL of deionized water, stir with a magnetic stirrer (500r / min) for 10 minutes, and sonicate for 5 minutes until completely dissolved to obtain a precursor solution with a total mass ratio of 6.667% for citric acid and cysteine. S32: Pour the precursor solution into a 50 mL polytetrafluoroethylene reactor, heat it in an 800 W household microwave oven for 3 minutes, and then let it cool naturally to room temperature. Transfer the cooled solution to a centrifuge tube and centrifuge at 6000 rpm for 2 minutes. Filter the supernatant through a 0.22 μm organic filter membrane to remove large particulate impurities. Place the filtrate into a dialysis bag with a molecular weight cutoff of 3500 Da and dialyze it in deionized water for 24 hours (replacing the deionized water every 6 hours). After dialysis, transfer the solution to a freeze dryer and freeze it at -60 °C for 12 hours, followed by sublimation drying under a vacuum of 5 Pa for 42 hours to obtain a pale yellow N,S-CDs powder. Weigh 0.2 g of this powder, add it to 10 mL of deionized water, and ultrasonically disperse it for 10 minutes to obtain an N,S-CDs solution with a concentration of 0.02 g / mL. S33: Weigh 10g of polyacrylic acid (molecular weight 300,000), add it to 90mL of deionized water, and stir in a 60℃ water bath for 30 minutes until completely dissolved to obtain a 10% (w / w) polyacrylic acid solution; measure 10mL of a 2mg / mL graphene oxide aqueous solution (sheet diameter 0.5-2μm), add it to 100g of the polyacrylic acid solution, and stir for 20 minutes; then measure 10mL of the above N,S-CDs solution, add it to the mixture, and continue stirring for 30 minutes until homogeneous to obtain a mixed solution; S34: Pour the mixture into a mold with dimensions of 12cm×27cm×0.4cm and let it stand at room temperature for 2 hours to initially form the film; take out the formed film and immerse it in a calcium chloride aqueous solution with a concentration of 2mg / mL and crosslink it at room temperature for 24 hours; after crosslinking, rinse the film surface with deionized water 3 times to remove residual calcium chloride; put the film in a 45℃ oven to dry for 24 hours to obtain a 0.4cm thick N,S-CDs photo-antibacterial layer.

[0066] (4) Preparation of PDMS matrix (step S4).

[0067] S41: Select commercially available sugar cubes with a particle size of 5mm and spread them evenly on the bottom of a 12cm×27cm×2cm mold; weigh PDMS prepolymer and Sylgard184 curing agent at a mass ratio of 15:1, mix and stir for 15 minutes until uniform, pour into the mold, and ensure that the sugar cubes are completely immersed in the PDMS mixture. S42: Place the mold in a 100℃ oven to cure for 1 hour, then remove and cool to room temperature; S43: Remove the cured PDMS block from the mold and immerse it in 60°C deionized water for 2 hours, changing the deionized water twice during the process to fully dissolve the sugar cubes; after removal, rinse the surface with deionized water and air dry to obtain a porous PDMS matrix (porosity of about 60%).

[0068] (5) Layered assembly to obtain PDMS components (step S5).

[0069] S50: An anisotropic conductive film (ACF, 50μm thick, 3μm diameter conductive particles) is cut into 12cm×27cm size, pre-attached to the bottom surface of 22 CNT / ACET / PDMS pressure sensor electrodes, placed in a hot pressing device, and hot-pressed at 150℃ and 8MPa pressure for 60 seconds to complete the flexible interconnection. S51: Cut the porous PDMS matrix into an insole shape of 11cm×26cm; S52: The 22 pressure sensors are embedded in the pre-set grooves on the upper surface of the PDMS substrate, with 8 in the forefoot area, 6 in the midfoot area, and 8 in the heel area, to ensure that the sensors fit tightly to the substrate. S53: Attach the printed circuit board (PCB, size 5cm×3cm, integrated signal interface) to the middle foot area of ​​the upper surface of the PDMS substrate, apply 0.2cm thick uncured PDMS coating to the connection between the PCB and the sensor, and let it stand at room temperature for 30 minutes for initial fixation; S54: The signal acquisition and transmission module (including ADC chip ADS1232, MCU chip ESP32-C3, BLE module nRF52832), the energy management module (including LTC3588-1 chip, 10mF supercapacitor), and the intelligent control module (including SHT40 humidity sensor, Bluetooth communication unit) are embedded in the bottom middle of the PDMS substrate, slightly towards the rear heel area (4cm×3cm). S55: The printed circuit board is connected to each functional module through a 0.5mm diameter wire hole, and the wire connection is sealed with insulating glue. S56: Six 365nm ultraviolet LEDs (0.5W power) are evenly distributed around the area to be covered by the N,S-CDs photo-antibacterial layer by passing wires through the side of the PDMS substrate and connecting the wires to the energy management module. S57: Cover the PDMS substrate with the N,S-CDs photo-antibacterial layer to ensure complete coverage of the sensor and PCB area, thus obtaining the PDMS assembly.

[0070] (6) Composite of piezoelectric energy layer with PDMS component (step S6).

[0071] S61: Place the prepared piezoelectric energy layer into a mold of 12cm×27cm×0.5cm, pour in uncured PDMS, control the total thickness to 0.5cm, and place it in a 100℃ oven for semi-curing for 0.5 hours; S62: After connecting the PDMS component to the energy management module via wires, flip it over and place it on top of the piezoelectric energy layer (with the bottom of the PDMS component facing the piezoelectric energy layer); cover the piezoelectric energy layer with a 0.1mm thick PI film (12cm×27cm in size), and place the whole assembly in a 100℃ oven for semi-curing again for 0.5 hours. After cooling, the composite component is obtained.

[0072] (7) Cover the surface with a PI / PDMS encapsulation layer (step S7).

[0073] S71: Cover the surface of the N,S-CDs photo-antibacterial layer of the composite component with an uncured PI / PDMS composite film (PI content 60%, thickness 0.1mm, size 12cm×27cm), place it in a hot press and hot press at 80°C for 5 minutes; then transfer it to a 150°C oven for curing for 2 hours, cool it to room temperature and cut off the excess parts at the edges to obtain the carbon dot antibacterial insole of Example 1.

[0074] Example 2 The manufacturing method of the carbon dot antibacterial insole in Example 2 is basically the same as that in Example 1, except that: CNT / ACET / PDMS pressure sensor: In step S11, the ultrasonic dispersion time is adjusted to 2 hours, and in step S12, the curing temperature is adjusted to 80℃ and the curing time is adjusted to 1 hour. The number of sensor units is reduced to 20 (7 in the forefoot area, 6 in the midfoot area, and 7 in the heel area). Piezoelectric energy layer: In step S21, the radius of the PVDF circular unit is adjusted to 0.5cm and the array spacing is adjusted to 0.8cm. In step S22, the graphene coating amount is adjusted to 0.05mg / cm² and the drying temperature is adjusted to 80℃. N,S-CDs photo-antibacterial layer: In step S32, the centrifugation speed is adjusted to 5000 rpm and the vacuum sublimation drying time is adjusted to 36 hours; in step S34, the antibacterial layer thickness is adjusted to 0.3 cm and the drying temperature is adjusted to 50℃. PDMS matrix: In step S41, the sugar particle size was adjusted to 4 mm, and in step S43, the soaking time in deionized water was adjusted to 1.5 hours; Layered assembly and lamination: In step S56, the number of UV LEDs is reduced to 4; in S61, the semi-curing time is adjusted to 40 minutes; and in S71, the hot pressing temperature is adjusted to 85℃ and the curing time is adjusted to 1.5 hours.

[0075] Comparative Example 1 The manufacturing method of the insole in Comparative Example 1 is basically the same as that in Example 1, except that: Step S3 (preparation of N,S-CDs photo-antibacterial layer) is omitted: a 0.4cm thick ordinary cotton fiber membrane is directly used to replace the N,S-CDs photo-antibacterial layer and is applied to the upper surface of the PDMS substrate. Step S6 (composite piezoelectric energy layer and PDMS component) is omitted: the piezoelectric energy layer preparation is cancelled, and a 0.1mm thick PI film is directly pasted on the bottom of the PDMS component. The power supply method of the functional module is changed to a built-in replaceable 3.7V button battery (capacity 100mAh). Local adjustments: Due to the absence of a piezoelectric energy layer, the power of the ultraviolet LED in S56 is reduced to 0.2W to avoid insufficient battery life of the button cell; the flexible interconnect structure in S50 is removed (due to the absence of a piezoelectric energy layer and the need for coordinated power supply to the sensor).

[0076] Referring to GB / T3903.1-2008, GB / T3903.2-2008, and GB / T20944.3-2008, the performance of the insoles prepared in Examples 1-2 and Comparative Example 1 was tested: (1) Cyclic bending test: The insole was fixed on a bending fixture with a curvature radius of 10mm using a shoe upper bending tester. The bending angle was set to ±30° and the bending frequency was 30 times / minute. The test was conducted continuously for 10,000 times. The sensitivity (0-225kPa pressure range) and circuit continuity (Z-axis resistance) of the CNT / ACET / PDMS pressure sensor were tested before and after the test.

[0077] (2) Cyclic compression test: Using a universal material testing machine, 0-150 kPa cyclic pressure (simulating daily walking pressure) was applied to the forefoot area, midfoot area and heel area of ​​the insole, respectively. The compression frequency was 1 time / second, and the test was conducted continuously for 180,000 times. After the test, the output voltage of the piezoelectric energy layer (under walking conditions) and the structural integrity of the N,S-CDs photo-antibacterial layer were detected (no cracking or peeling).

[0078] (3) Antibacterial rate test: The N,S-CDs photo-antibacterial layers of Example 1 and Example 2 and the cotton fiber membrane of Comparative Example 1 were cut into 2cm×2cm samples, and the inoculation concentration was 1×10. 6 After incubating CFU / mL suspensions of Staphylococcus aureus (ATCC25923) and Escherichia coli (ATCC25922) at 37°C with shaking for 24 hours, the inhibition rate was calculated using the plate count method. At the same time, a UV LED (0.5W power, irradiation distance 1cm) was turned on to test the photosynergistic antibacterial effect.

[0079] (4) Washability test: The sample was washed 5 times according to the "GB / T8629-2017 Home Washing and Drying Procedures for Textiles" (water temperature 40℃, washing time 30 minutes). After washing, the above antibacterial rate test was repeated to evaluate the decay of antibacterial performance.

[0080] The test results of cyclic bending and cyclic compression tests for Examples 1-2 and Comparative Example 1 are shown in Table 1: Table 1 The test results of antibacterial rate and washability of Examples 1-2 and Comparative Example 1 are shown in Table 2: Table 2 Comparative Example 1 lacks a core functional layer and has no piezoelectric power supply. This results in a significant increase in circuit resistance, wrinkling of the cotton fiber membrane, and a substantial decrease in antibacterial rate after washing, making it unsuitable for long-term wear. The insole prepared using the method provided in this application comprises a complete piezoelectric energy layer, an N,S-CDs photo-antibacterial layer, and a flexible interconnect structure. It exhibits good sensor sensitivity and circuit stability, maintains a good antibacterial rate before and after washing, and can achieve self-powered operation, ensuring both detection and antibacterial effects.

[0081] It should be understood that the application of this application is not limited to the examples above. Those skilled in the art can make improvements or modifications based on the above description, and all such improvements and modifications should fall within the protection scope of this application.

Claims

1. A method for manufacturing a carbon dot antibacterial insole, characterized in that, Includes the following steps: Fabrication of CNT / ACET / PDMS pressure sensors; Fabrication of piezoelectric energy layers; Preparation of N,S-CDs photo-antibacterial layer; Preparation of PDMS matrix; The CNT / ACET / PDMS pressure sensor and the N,S-CDs photo-antibacterial layer are layered and assembled on the PDMS substrate to obtain a PDMS component. The piezoelectric energy layer is combined with the assembled PDMS component; The surface is covered with a PI / PDMS encapsulation layer to obtain the carbon dot antibacterial insole.

2. The method for manufacturing carbon dot antibacterial insoles according to claim 1, characterized in that, The steps for preparing the CNT / ACET / PDMS pressure sensor include: Carbon nanotubes were added to ethyl acrylate and dispersed to obtain a dispersion. The polydimethylsiloxane prepolymer was mixed with Sylgard184 curing agent, added to the dispersion, stirred and degassed, poured into a mold and cured, and then connected to a copper electrode.

3. The method for manufacturing carbon dot antibacterial insoles according to claim 1, characterized in that, The step of preparing the piezoelectric energy layer includes: Prepare a PVDF film by cutting the PVDF film into circular units and laying them in an array on a copper foil electrode; A graphene coating solution is coated onto the surface of the copper foil electrode and then dried. The PVDF film has a thickness of 0.2 mm, the circular unit has a radius of 0.5-0.8 cm, and the array spacing is 0.8-1 cm. The graphene coating solution contains 1.5% graphene by mass, and the coating amount is 0.05-0.1 mg / cm³. 2 The drying temperature is 60-80℃.

4. The method for manufacturing carbon dot antibacterial insoles according to claim 1, characterized in that, The steps for preparing the N,S-CDs photo-antibacterial layer include: Citric acid and cysteine ​​were dissolved in deionized water to obtain a precursor solution; After microwave heating and cooling, centrifugation, filtration through a filter membrane, dialyzing, freezing, and vacuum sublimation drying, N,S-CDs powder was obtained and dispersed in deionized water to obtain N,S-CDs solution. Polyacrylic acid was dissolved in deionized water to obtain a polyacrylic acid solution, which was then mixed with a graphene oxide solution, and finally the N,S-CDs solution was added to obtain a mixture. After the mixture is shaped, it is immersed in a calcium chloride solution for crosslinking, then washed and dried.

5. The method for manufacturing carbon dot antibacterial insoles according to claim 4, characterized in that, The mass ratio of citric acid to cysteine ​​is 2:1, and the total weight of citric acid and cysteine ​​accounts for 6-7% of the mass of the precursor solution. The microwave heating is performed in an 800W microwave oven for 3 minutes; the centrifugation speed is 5000-7000 rpm for 2 minutes; the pore size of the filter membrane is 0.22 μm; the dialysis time is 24 hours; the freezing temperature is -50~-80℃ for 12 hours; and the vacuum sublimation drying is performed at a vacuum degree of 1-10 Pa for 36-48 hours. The polyacrylic acid solution has a mass concentration of 10% and the graphene oxide solution has a concentration of 2 mg / mL, with a ratio of 10 ml to 100 g. The concentration of the N,S-CDs solution is 0.02 g / mL, and the ratio of the N,S-CDs solution to the polyacrylic acid solution is 10 ml: 100 g. The concentration of the calcium chloride solution is 2 mg / mL, the crosslinking time is 24 hours, and the drying temperature after washing is 40-50℃ for 24 hours. The thickness of the N,S-CDs photo-antibacterial layer is 0.3-0.5 cm.

6. The method for manufacturing carbon dot antibacterial insoles according to claim 1, characterized in that, The steps for preparing the PDMS matrix include: Using commercially available sugar cubes as a water-soluble template, the sample was immersed in a mixed solution of PDMS prepolymer and curing agent; Place in the mold and cure at 100℃ for 1 hour; After removing the sugar cubes, immerse them in 60℃ deionized water for 2 hours to dissolve them. The mass ratio of the PDMS prepolymer to the curing agent is 15:1, and the thickness of the mold is 2cm.

7. The method for manufacturing carbon dot antibacterial insoles according to claim 1, characterized in that, The layered assembly steps include: The PDMS substrate is cut into the shape of an insole; Multiple CNT / ACET / PDMS pressure sensors are embedded into the surface of the PDMS substrate in sections for the forefoot, midfoot, and heel areas. After bonding to the printed circuit board, a 0.2cm thick PDMS coating is applied; The signal acquisition and transmission module, energy management module, and intelligent control module are embedded in the area near the heel of the bottom center of the PDMS substrate. Connect the printed circuit board via wire through-holes; The ultraviolet LED is connected to the energy management module by passing a wire through a hole in the side of the PDMS substrate; The N,S-CDs photo-antibacterial layer is then applied to the surface of the PDMS substrate.

8. The method for manufacturing carbon dot antibacterial insoles according to claim 7, characterized in that, The layered assembly also includes the fabrication of flexible interconnect structures, comprising the following steps: The anisotropic conductive film is cut to the shape of an insole and pre-attached to the bottom surface of the CNT / ACET / PDMS pressure sensor electrode, and then hot-pressed at 150°C and 8MPa for 60 seconds.

9. The method for manufacturing carbon dot antibacterial insoles according to claim 8, characterized in that, The composite step includes: The piezoelectric energy layer was placed in a mold, PDMS was added to control the thickness to 0.5 cm, and it was semi-cured at 100°C for 0.5 hours. After connecting the PDMS component to the energy management module via wires, place it above the piezoelectric energy layer, cover the piezoelectric energy layer with a PI layer, and semi-cur the whole at 100°C for 0.5 hours. The step of covering the surface with a PI / PDMS encapsulation layer includes: An uncured PI / PDMS film was placed over the surface of the N,S-CDs photo-antibacterial layer, hot-pressed at 80°C for 5 minutes, and then cured at 150°C for 2 hours.

10. A carbon dot antibacterial insole, characterized in that, It is prepared by the method of manufacturing carbon dot antibacterial insoles as described in any one of claims 1-9.

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