Foamed nickel / barium titanate / flexible material high-dielectric composite material as well as preparation method and application thereof

Abstract

The invention discloses a foamed nickel / barium titanate / flexible material high-dielectric composite material as well as a preparation method and application thereof, and relates to the technical field of medical instruments. The foamed nickel / barium titanate / flexible material high-dielectric composite material comprises foamed nickel, barium titanate coating the surface of the foamed nickel and a flexible material filled in the barium titanate and the foamed nickel. The flexible material comprises a polymer, and the polymer comprises at least two of PDMS silica gel, a polyurethane elastomer, epoxy resin, acrylic resin, polyester, SEBS, polyether ester, PI, PVDF, PVDF-HFP, polyether-ether-ketone and polyether sulfone. The composite material disclosed by the invention has the characteristics of high dielectric property, low loss and good flexibility.

Description

Technical Field

[0001] This invention relates to the technical field of medical devices, and more particularly to a high-dielectric composite material of nickel foam / barium titanate / flexible material, its preparation method, and its application. Background Technology

[0002] Tumor electric field therapy (TTF) utilizes low-intensity, medium-frequency (100-500 kHz), alternating electric fields to act on human tissues, interfering with the mitotic process of cells and thus inhibiting and destroying rapidly proliferating cells. It is primarily used for the treatment of tumors. This type of tumor treatment is known internationally as alternating electric field therapy or Tumor Treating Fields (TTFields, hereinafter referred to as TTF), and it is a technology that developed after 2000. To date, phase III clinical trials for various tumors have yielded promising results, making it a promising tumor treatment technology.

[0003] Existing TTF devices mostly use small-sized rigid ceramic electrode pads. Due to the curvature of the human body, there are warped edges, voids, and stress concentrations, which reduces the effective coupling area and increases the interfacial air gap. This results in a decrease in the equivalent coupling capacitance, and under the condition of limited port voltage, the electric field strength and energy coupling efficiency within the tissue are limited. Furthermore, the thickness and impermeability of rigid ceramic electrode pads can easily cause skin irritation and inflammation, affecting long-term compliance (>18 hours / day). Summary of the Invention

[0004] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a high-dielectric composite material of nickel foam / barium titanate / flexible material, its preparation method, and its application. The composite material of this invention features high dielectric strength, low loss, and good flexibility. When applied to a flexible high-dielectric patch electrode with surface capacitive coupling in a 100-500 kHz mid-frequency alternating electric field, it can significantly improve the internal electric field strength and depth coverage without increasing the device's output voltage, while simultaneously reducing instrument power consumption.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: In a first aspect, the present invention provides a high dielectric composite material of nickel foam / barium titanate / flexible material, comprising nickel foam, barium titanate coated on the surface of nickel foam, and flexible material filled in barium titanate and nickel foam; The flexible material includes a polymer, which includes at least two of PDMS silicone, polyurethane elastomer, epoxy resin, acrylic resin, polyester, SEBS, polyether ester, polyimide (PI), PVDF, PVDF-HFP, polyetheretherketone, and polyethersulfone.

[0006] This invention, by using at least two different polymers compounded with barium titanate and nickel foam, enables flexible materials to better fill the pores of nickel foam and barium titanate, thereby giving the composite material the characteristics of high dielectric constant, low loss, and good flexibility.

[0007] The flexible material described in this invention uses two different polymers that can be mixed in a co-fusion manner, for example, a mixed solution of PVDF-HFP and PI can be used to encapsulate the nickel foam / barium titanate material, or they can be mixed in different layer structures (for example, the upper layer of the nickel foam / barium titanate material can be encapsulated with PVDF, and the lower layer can be encapsulated with polyacrylic acid hydrogel, the two polymer layers are completely separated, so that the upper material is in contact with the wires in the direction of contact with the outside of the body, while the lower material is in contact with the body surface. Because the lower layer of polyacrylic acid hydrogel has a high viscosity, it can adhere the composite material to the body surface).

[0008] Alternatively, a small amount of PVDF can be applied to the entire nickel / barium titanate foam material to retain some voids in the composite material. Then, polyacrylic acid hydrogel can be applied to encapsulate the nickel / barium titanate foam material with PVDF to maintain its dielectric properties, and then sealed with polyacrylic acid hydrogel to maintain its overall adhesiveness, allowing it to be directly adhered to the body.

[0009] Preferably, the polymer comprises PVDF-HFP and PI, and the mass ratio of PVDF-HFP to PI is (80-95):(5-20).

[0010] This invention improves the dielectric constant of the composite material by controlling the mass ratio of PVDF-HFP and PI, while also reducing the dielectric loss of the composite material.

[0011] Preferably, the polymer comprises PDMS silicone and PVDF, and the mass ratio of the PDMS silicone to PVDF is (70-90):(10-30).

[0012] This invention improves the softness and skin-friendliness of composite materials by controlling the mass ratio of PDMS silicone and PVDF, thereby reducing the Shore hardness of the composite material.

[0013] Preferably, the polymer comprises polyurethane elastomer and SEBS, and the mass ratio of the polyurethane elastomer to SEBS is (70-90):(10-30).

[0014] This invention improves the wear resistance and resilience of composite materials by controlling the mass ratio of polyurethane elastomer and SEBS.

[0015] Preferably, the high dielectric composite material of the foamed nickel / barium titanate / flexible material has a dielectric constant ≥2000, a dielectric loss ≤0.3, and a Shore hardness of 20-70 at a frequency of 200KHz.

[0016] Preferably, the polymer has a viscosity of 100-20000 mPa·s at 25°C. The viscosity of the polymer described in this invention is obtained by testing using ASTM D1084 / D2196.

[0017] Preferably, the flexible material further includes 1-30 wt% conductive binder and 0.5-40 wt% functional additives.

[0018] Preferably, the conductive adhesive comprises at least one of polyvinyl alcohol (PVA) hydrogel, polyacrylic acid (PAA) hydrogel, polyvinylpyrrolidone (PVP) hydrogel, carbomer gel, and sodium carboxymethyl cellulose gel. This invention achieves conductive coupling and comfort by appropriately incorporating physiological saline or electrolytes.

[0019] Preferably, the functional additive includes at least one of thermally conductive materials, phase change materials, anti-inflammatory / antibacterial components, plasticizers, and thickeners.

[0020] More preferably, the thermally conductive material includes at least one of hexagonal boron nitride (BN) and aluminum nitride (AlN).

[0021] More preferably, the D50 particle size of the hexagonal boron nitride is 1-40 μm, more preferably 5-30 μm; and the specific surface area (BET) is 1-20 m². 2 / g, preferably 2-10 m 2 / g.

[0022] More preferably, the aluminum nitride has a D50 particle size of 5-80 μm, more preferably 10-50 μm, and a specific surface area of ​​0.2-5 m². 2 / g, preferably ≤3 m 2 / g.

[0023] More preferably, the phase change material includes at least one of paraffin microcapsules and PCM microcapsules.

[0024] More preferably, the D50 particle size of the phase change microcapsules is 2-30 μm, and more preferably 5-20 μm.

[0025] This invention improves the heat dissipation of composite materials by adding thermally conductive or phase change materials.

[0026] Preferably, the thermally conductive filler content in the flexible material is 5-30 wt%.

[0027] Preferably, the phase change material content in the flexible material is 2-15 wt%.

[0028] Preferably, the anti-inflammatory / antibacterial component includes at least one of zinc oxide (ZnO), quaternary ammonium salt, polyhexamethylene guanidine (PHMB), and iodine tincture, with an addition amount of 1-5 wt%, which is beneficial to improving the antibacterial properties of the composite material.

[0029] Preferably, the plasticizer includes phthalates, aliphatic diacidates, silicone oils, carbonates, etc., and the amount added is 5-30 wt%.

[0030] Preferably, the tackifier includes terpenes, rosin, petroleum resin, etc., and the amount added is 20-40 wt%.

[0031] This invention improves the tactile feel of composite materials by adding plasticizers and tackifiers to flexible materials.

[0032] Preferably, the nickel foam has an open porosity of 70-99%, an average pore size of 30-1500 μm, and a thickness of 5-3000 μm.

[0033] More preferably, the open-cell ratio of the nickel foam is 85-98%, and even more preferably 90-97%.

[0034] More preferably, the average pore size of the nickel foam is 100-800 μm, and even more preferably 150-600 μm.

[0035] More preferably, the thickness of the nickel foam is 50-1200 μm.

[0036] The nickel foam described in this invention has an surface resistivity of ≤1.0 Ω / m at 200 kHz. 2 Preferably ≤0.3 Ω / m 2 It can maintain a continuous conductive network when sintered in an inert atmosphere (air atmosphere or various common mixed gas atmospheres) at >1000°C.

[0037] Preferably, the mass ratio of the foamed nickel, barium titanate, and flexible material is (1-6):(2-8):(8-14), more preferably (2-5):(3-7):(9-13). The high-dielectric composite material using the above mass ratio is of the "lightweight-high flexibility" type. The barium titanate has a smaller thickness, and combined with the porous nature of the flexible material, it is suitable for products with large curvature or moving parts.

[0038] Secondly, the present invention also provides a method for preparing a high-dielectric composite material of nickel foam / barium titanate / flexible material, comprising the following steps: (1) Add barium titanate powder to an organic solvent and stir for 3-4 h, then sonicate for 20-30 min to obtain a mixed solution after uniform dispersion; (2) Electrophoretic deposition is performed using a DC power supply, with a platinum sheet as the positive electrode and nickel foam as the negative electrode. The spacing between the nickel foam and the platinum sheet is 10-25 mm, and deposition is carried out at a voltage of 40V. The deposition time is set to 8-10 min for single-sided electroplating, and electroplating is performed once on each side. (3) Under a protective atmosphere, sinter at 1000-1300℃ for 1-2 h, and after cooling, a composite material of barium titanate coated nickel foam is obtained; (4) Inject the flexible material into the pores of the composite material of barium titanate coated nickel foam to obtain the high dielectric composite material of nickel foam / barium titanate / flexible material.

[0039] Preferably, polyethyleneimine may be added in step (1) to allow barium titanate to better coat the surface of the nickel foam, thereby improving the performance of the composite material. Furthermore, polyethyleneimine decomposes after high-temperature sintering without affecting the material's performance.

[0040] Preferably, in step (2), the nickel foam is pretreated, and the specific steps are as follows: S1: Immerse the nickel foam in acetone solution and ultrasonically clean for 20-30 minutes; S2: After removing the acetone solution, add deionized water and continue sonication for 10-15 min. S3: Remove deionized water, then add anhydrous ethanol and sonicate for 10-15 minutes for cleaning.

[0041] Preferably, the average particle size of the barium titanate powder is 10 nm to 5 μm, more preferably 30-300 nm, and even more preferably 50-200 nm. It can be used in conjunction with a dispersant to make the powder particles disperse more stably.

[0042] Preferably, the barium titanate powder has a specific surface area (BET) of 2-100 m². 2 / g, preferably 5-25 m 2 / g.

[0043] Preferably, the particle size distribution of the barium titanate powder is: D90 / D10≤10, more preferably ≤5.

[0044] It should be noted that D10 refers to the particle size corresponding to a cumulative distribution of 10%, meaning that 10% of the particles have a particle size smaller than this value; while D90 refers to the particle size corresponding to a cumulative distribution of 90%, meaning that 90% of the particles have a particle size smaller than this value.

[0045] Preferably, the apparent thickness of the barium titanate after sintering is 5-300 μm, and more preferably 10-100 μm.

[0046] Preferably, the grain size of the barium titanate after sintering is 0.2-10 μm, more preferably 0.5-5 μm, which can balance the dielectric constant, dielectric loss and mechanical compliance.

[0047] Preferably, the porosity (within the shell) of the barium titanate after sintering is 0-10%, preferably ≤5%, which can avoid the increase of dielectric loss.

[0048] Thirdly, the present invention also provides the application of a high-dielectric composite material of nickel foam / barium titanate / flexible material in a patch electrode for tumor electric field therapy.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. In this invention, nickel foam forms a continuous conductive network, and barium titanate can uniformly and continuously coat the nickel foam, significantly improving the dielectric properties of the composite material. Simultaneously, interfacial polarization enhances the dielectric constant. The flexible material, by filling the pores within the nickel foam and barium titanate, improves the softness and comfort of the high-dielectric composite material. Therefore, this invention, through the synergistic use of nickel foam, barium titanate, and the flexible material, results in a composite material with high dielectric constant, low loss, and good flexibility.

[0050] 2. This invention can significantly improve therapeutic efficacy and reduce energy consumption. The electric field strength at the tumor site is a decisive factor in the effectiveness of TTF treatment. Due to the limitations of wearable devices in terms of applied voltage, increasing the field strength within the body encounters a bottleneck. This invention, through a large, flexible patch that fits perfectly against the body and has a high dielectric constant, can significantly increase the electric field strength at the tumor site, thereby enhancing therapeutic efficacy. Simultaneously, since the device operates for at least 18 hours a day, the frequency of battery replacement is a crucial consideration affecting patient compliance. This invention achieves the same internal electric field as current high-voltage devices using a lower voltage, thus reducing device power consumption.

[0051] 3. The patch processing steps described in this invention are fewer, less costly, and lighter. Competing products use a multi-layer bonding process, while this invention employs an integrated processing method, resulting in lower cost and weight compared to competing products. This can help address patients' financial difficulties and improve their adherence to treatment.

[0052] 4. The high-dielectric composite material described in this invention is fully breathable, which can suppress the side effects of scalp irritation and offers strong customization capabilities. Product design and processing technology dictate that a significant portion of competing products are not breathable, while the patch described in this invention can be easily perforated, making the entire patch breathable, thereby suppressing treatment irritation to the scalp. Simultaneously, the flexible transducer of this invention can be directly cut and processed, greatly reducing the difficulty of secondary processing and thus supporting personalized customization. Attached Figure Description

[0053] Figure 1This is a simulation model diagram used to test the electric field strength in the human brain.

[0054] Figure 2 This is a comparison image of the electric field generated in the human brain by a 2cm diameter fully rigid and fully flexible ceramic patch electrode.

[0055] Figure 3 This is a scanning electron microscope image of the cross-section of the nickel foam in Example 1.

[0056] Figure 4 This is a scanning electron microscope image of the cross-section of the barium titanate plated in Example 1.

[0057] Figure 5 This is a scanning electron microscope image of the cross-section of the material after high-temperature sintering in Example 1.

[0058] Figure 6 This is a scanning electron microscope image of the cross-section of the material after gel casting in Example 1. Detailed Implementation

[0059] To better illustrate the purpose, technical solution, and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments, but the scope of protection and implementation of the present invention are not limited thereto.

[0060] Unless otherwise specified, the materials and reagents used in the following examples are commercially available.

[0061] Example 1 This embodiment discloses a high dielectric composite material of nickel foam / barium titanate / flexible material, including nickel foam, barium titanate coated on the surface of nickel foam, and flexible material filling the pores of nickel foam and barium titanate; The mass ratio of the foamed nickel, barium titanate, and flexible material is 3:6:10.

[0062] The flexible material comprises a polymer, which includes PVDF-HFP and PI, and the mass ratio of PVDF-HFP to PI is 80:20.

[0063] This embodiment also discloses a method for preparing a high-dielectric composite material of nickel foam / barium titanate / flexible material, including the following steps: (1) Pretreatment of nickel foam is carried out, and the specific steps are as follows: S1: Place the nickel foam in a beaker, add acetone solution to immerse the nickel foam, and ultrasonically clean for 30 min; S2: After removing the acetone solution, add deionized water and continue sonication for 15 min; S3: Remove deionized water, then add anhydrous ethanol and sonicate for 15 minutes for cleaning.

[0064] (2) Add 1 part of barium titanate powder and 0.5 parts of polyethyleneimine to a beaker, then add 50 parts of isopropanol, stir at room temperature for 4 h, then sonicate for 30 min to disperse evenly and obtain a mixed solution. The average particle size of the barium titanate powder is 100 nm, the particle size distribution is D90 / D10≤10, and the specific surface area is 5-25 m². 2 / g.

[0065] (3) Electrophoretic deposition was performed using a DC power supply, with a platinum sheet as the positive electrode and pretreated nickel foam as the negative electrode. The distance between the nickel foam and the platinum sheet was 10 mm, and deposition was carried out at a voltage of 40 V. The deposition time was set to 10 min for single-sided electroplating, and electroplating was performed once on each side.

[0066] (3) Under a nitrogen atmosphere, the temperature was raised from room temperature to 1300℃ and kept at that temperature for 2 hours. After cooling, a composite material of barium titanate coated nickel foam was obtained.

[0067] (4) Place the barium titanate-coated nickel foam composite material at 100℃ and dry for 30 min; place the flexible material (PVDF-HFP and PI blend solution) in a vacuum to degas for 10 min until the foam disappears; The dried barium titanate-coated nickel foam composite material was placed on a liquid receiving tray, and flexible material was slowly poured in until the sample was completely immersed in the barium titanate-coated nickel foam composite material. A vacuum was drawn and maintained for 5 minutes to allow the air in the pores of the barium titanate-coated nickel foam composite material to escape. Then, the pressure was slowly returned to normal, and the pressure difference was used to drive the flexible material into the pores of the barium titanate-coated nickel foam composite material, thus obtaining a high dielectric composite material of nickel foam / barium titanate / flexible material.

[0068] like Figure 3-6 As shown, the present invention uses scanning electron microscopy to capture the material structure diagrams after nickel foaming, barium titanate electroplating, sintering, and gel casting, respectively, showing that the materials were successfully composited at each step.

[0069] Example 2 The difference from Example 1 is that the mass ratio of the foamed nickel, barium titanate, and flexible material is 1:2:8.

[0070] Example 3 The difference from Example 1 is that the mass ratio of the foamed nickel, barium titanate, and flexible material is 6:2:14.

[0071] Example 4 The difference from Example 1 is that the mass ratio of PVDF-HFP to PI is 90:10.

[0072] Example 5 The difference from Example 1 is that the mass ratio of PVDF-HFP to PI is 95:5.

[0073] Example 6 The difference from Example 1 is that the polymer comprises PDMS silicone and PVDF, and the mass ratio of PDMS silicone to PVDF is 70:30.

[0074] Example 7 The difference from Example 1 is that the polymer comprises PDMS silicone and PVDF, and the mass ratio of PDMS silicone to PVDF is 90:10.

[0075] Example 8 The difference from Example 1 is that the polymer comprises polyurethane elastomer and SEBS, and the mass ratio of the polyurethane elastomer to SEBS is 70:30.

[0076] Example 9 The difference from Example 1 is that the polymer comprises polyurethane elastomer and SEBS, and the mass ratio of the polyurethane elastomer to SEBS is 90:10.

[0077] Example 10 The difference from Example 1 is that the flexible material comprises a polymer, polyvinyl alcohol hydrogel, and hexagonal boron nitride, and the mass ratio of the polymer, polyvinyl alcohol hydrogel, and hexagonal boron nitride is 70:20:10. The hexagonal boron nitride has a D50 particle size of 1-40 μm and a specific surface area of ​​1-20 m². 2 / g.

[0078] Example 11 The difference from Example 1 is that the flexible material comprises a polymer, a polyacrylic acid hydrogel, and paraffin microcapsules, and the mass ratio of the polymer, polyacrylic acid hydrogel, and paraffin microcapsules is 65:25:10. The D50 particle size of the paraffin microcapsules is 2-30 μm.

[0079] Comparative Example 1 The difference from Example 1 is that the flexible material comprises only PVDF-HFP.

[0080] Comparative Example 2 The difference from Example 1 is that the flexible material comprises only PI.

[0081] Comparative Example 3 The difference from Example 1 is that an equal mass of polyethylene is used instead of PVDF-HFP.

[0082] Performance testing The following performance tests were performed on the high dielectric composite materials of nickel foam / barium titanate / flexible material prepared in Examples 1-11 and Comparative Examples 1-3, respectively.

[0083] 1. Dielectric constant and dielectric loss test The testing standard was as follows: All samples were cut into flat plates approximately 1.0 mm thick and 20 mm × 20 mm in area. After vacuum drying at 80℃ for 2 h, silver electrodes were formed on both sides of the samples by sputtering. The dielectric constant and dielectric loss were tested according to GB / T1409-2006 "Determination of Dielectric Constant and Dielectric Loss Factor of Solid Electrical Insulating Materials" standard, using the parallel plate capacitance method. Tests were conducted at 25℃ and 50% relative humidity using an LCR meter (Keysight E4980A, with matching parallel plate capacitance test fixture) within a frequency range of 100-500 kHz. The dielectric constant and dielectric loss data listed in Table 1 are values ​​measured at 200 kHz.

[0084] 2. Flexibility Test The test method is as follows: referring to GB / T 531.1-2008 "Test method for indentation hardness of vulcanized rubber or thermoplastic rubber - Shore hardness tester method", using an LX-A type Shore A hardness tester, the sample is made into a 50 mm × 50 mm × 2 mm plate, and 5 different positions are tested at 25 °C. The average value is taken as the compliance hardness index.

[0085] The test results are shown in Table 1.

[0086] Table 1 As shown in Table 1, the present invention uses nickel foam, barium titanate, and flexible materials in combination to make the composite material have the characteristics of high dielectric constant, low loss, and good flexibility, and is suitable for flexible high dielectric constant patch electrodes with surface capacitive coupling in 100-500 kHz medium frequency alternating electric fields.

[0087] An investigation into the electric field strength generated in the brain by flexible patch electrodes and rigid electrodes. 1. Modeling parameter settings (1) Outer radius of head (including scalp): Rhead = 92 mm; (2) Scalp thickness: 3 mm; (3) Skull thickness: 7 mm; (4) Cerebrospinal fluid thickness: 2 mm; (5) Radius of brain parenchyma: 80 mm (innermost layer); (6) Tumor: radius rtumor=10 mm, located in the brain about 20 mm below the scalp; (7) Gel thickness: 1mm (cylinder, covering between ceramic and scalp); (8) The ceramic patch has a thickness of 1mm, but different values ​​for diameter and dielectric constant.

[0088] 2. Taking glioma as an example, the finite element electric field intensity simulation in the brain uses a 200KHz frequency, sine wave, and 50Vpp voltage to be transmitted to the skin surface through a dielectric ceramic sheet and gel patch, and then further transmitted to the tumor site in the brain.

[0089] The electric field strength generated at the brain tumor site by rigid and flexible ceramic sheets with a diameter of 2 cm was compared. Since the human brain is approximately spherical, a spherical model was used to represent the brain for easier comparison of the performance of the rigid and flexible ceramic sheets. (See model image). Figure 1 Fully rigid and fully flexible represent two extreme cases of Shore hardness. By comparing these two cases, the effect of the ceramic sheet's flexibility on increasing the electric field strength at the tumor site can be clearly seen. The fully flexible ceramic sheet tested was made from the foamed nickel / barium titanate / flexible high-dielectric composite material prepared in Example 1.

[0090] This invention is only intended to illustrate the difference in the magnitude of the electric field intensity in the brain caused by the properties of rigid and flexible ceramics and their fit to the head. Therefore, only one pair of ceramic electrodes was selected for simulation comparison to obtain intuitive comparison results. It does not represent the magnitude of the electric field intensity in the brain during actual tumor electric field therapy (in actual use, dozens of ceramic electrodes are usually used to form an electric field transducer array to enhance the electric field intensity of brain tumors).

[0091] like Figure 2 As shown, because rigid ceramic cannot be bent and cannot conform to the curvature of the head, severe edge warping occurs. That is, only a small portion of the ceramic in close contact with the skin generates an electric field, with a maximum electric field strength of (~4×10⁻⁶). 4 The electric field strength (V / m) appears at the scalp area where the ceramic electrode is in close contact with the skin. This small area with a very high electric field strength can easily damage the skin. Meanwhile, the electric field strength inside the tumor (at its very center) is relatively low, approximately 0.57 V / m. In contrast, fully flexible ceramic, due to its ability to closely conform to the curvature of the head, has a maximum electric field strength at the scalp area where it is in contact with the head that is one order of magnitude lower than that of hard ceramic, thus protecting the scalp from electric field damage. Furthermore, the electric field strength inside the tumor (at its very center) is 15.2 V / m, 27 times that of a fully rigid ceramic electrode, demonstrating a significant advantage. Therefore, the better the flexibility of the ceramic, i.e., the lower its Shore hardness, the greater the electric field strength at the tumor site, and the better its performance.

[0092] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the essence and scope of the technical solutions of the present invention.

Claims

1. A high dielectric nickel / barium titanate / flexible material composite foam, characterized in that, The flexible material comprises a polymer, and the polymer comprises at least two of PDMS silicone gel, polyurethane elastomer, epoxy resin, acrylic resin, polyester, SEBS, polyether ester, PI, PVDF, PVDF-HFP, polyether ether ketone, and polyether sulfone. The polymer comprises PVDF-HFP and PI, and the mass ratio of the PVDF-HFP to the PI is (80-95):(5-20).

2. The foam nickel / barium titanate / flexible material high dielectric composite of claim 1, wherein, Or, the polymer comprises PDMS silicone gel and PVDF, and the mass ratio of the PDMS silicone gel to the PVDF is (70-90):(10-30). Or, the polymer comprises polyurethane elastomer and SEBS, and the mass ratio of the polyurethane elastomer to the SEBS is (70-90):(10-30).

3. The foam nickel / barium titanate / flexible material high dielectric composite material of claim 1, wherein the dielectric constant of the foam nickel / barium titanate / flexible material high dielectric composite material is ≥2000 at a frequency of 200 KHz, the dielectric loss is ≤0.3, and the Shore hardness is 20-70. The flexible material further comprises 1-30 wt% of a conductive binder and 0.5-40 wt% of a functional additive.

4. The foam nickel / barium titanate / flexible material high dielectric composite of claim 1, wherein, The conductive binder comprises at least one of polyvinyl alcohol hydrogel, polyacrylic acid hydrogel, polyvinylpyrrolidone hydrogel, carbomer gel, and sodium carboxymethyl cellulose gel.

5. The foam nickel / barium titanate / flexible material high dielectric composite of claim 4, wherein, And / or, the functional additive comprises at least one of a heat-conducting material, a phase-change material, an anti-inflammatory / antibacterial component, a plasticizer, and a tackifier. The heat-conducting material comprises at least one of hexagonal boron nitride and aluminum nitride.

6. The foam nickel / barium titanate / flexible material high dielectric composite of claim 5, wherein, And / or, the phase-change material comprises at least one of paraffin microcapsule and PCM microcapsule. And / or, the anti-inflammatory / antibacterial component comprises at least one of zinc oxide, quaternary ammonium salt, polyhexamethylene guanidine, and iodophor. And / or, the D50 particle size of the phase-change material is 2-30 μm. The mass ratio of the foam nickel, the barium titanate, and the flexible material is (1-6):(2-8):(8-14).

7. The foam nickel / barium titanate / flexible material high dielectric composite of claim 6, wherein, The D50 particle size of the hexagonal boron nitride is 1-40 μm, the specific surface area is 1-20 m 2 / g; or, the D50 particle size of the aluminum nitride is 5-80 μm, and the specific surface area is 0.2-5 m 2 / g.

8. The foam nickel / barium titanate / flexible material high dielectric composite of claim 1 wherein, The method comprises the following steps:

9. A method of preparing the foam nickel / barium titanate / flexible material high dielectric composite material according to any one of claims 1 to 8, characterized by, (1) stirring barium titanate powder in an organic solvent for 3-4 h, and then ultrasonicating for 20-30 min to obtain a mixed solution; (2) performing electrophoretic deposition by using a direct current power source, with a platinum sheet as a positive electrode and the foam nickel as a negative electrode, the distance between the foam nickel and the platinum sheet being 10-25 mm, and the deposition being performed at a voltage of 40 V; the deposition time is set to 8-10 min for single-side electroplating, and the positive and negative sides are each electroplated once; (3) sintering the foam nickel coated with the barium titanate in a protective atmosphere at 1000-1300 ℃ for 1-2 h, and obtaining the foam nickel / barium titanate composite material after cooling; (4) injecting a flexible material into the pores of the foam nickel / barium titanate composite material to obtain a foam nickel / barium titanate / flexible material high dielectric composite material.

10. Use of the foam nickel / barium titanate / flexible material high dielectric composite material of any one of claims 1-8 in a patch electrode for tumor electric field therapy. ​

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