Modified P (VDF-TrFE) sensor and preparation method thereof

Abstract

The invention provides a modified P (VDF-TrFE) sensor and a preparation method thereof, a flexible piezoelectric diaphragm is made of a vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) film piezoelectric material, has the characteristics of wide frequency band, good biocompatibility, softness and the like, can stably pick up a vibration acoustic signal by being coupled to a hammer bone neck of a human ossicular chain, and has the advantages of high sensitivity, high sensitivity and the like. Meanwhile, noise in the body can be avoided or weakened, electric hearing can be better achieved, meanwhile, better biocompatibility and durability are achieved, and the innovative cuboid laminated piezoelectric film-cantilever beam composite structure is beneficial to improving the conversion efficiency of vibration-voltage signals. The design of a redundant circuit is reduced, the signal-to-noise ratio is improved, and the speech perception ability of a user can be improved through a wider frequency spectrum and a better frequency response curve.

Description

Technical Field

[0001] The present invention relates to the technical field of cochlear implants, and in particular to a modified P (VDF-TrFE) sensor and a preparation method thereof. Background Art

[0002] Cochlear implants are medical devices that use functional electrical stimulation to directly excite residual spiral nerve cells to restore hearing in patients with profound or severe sensorineural hearing loss. In recent years, cochlear implants have become the standard treatment for patients with moderate to severe bilateral sensorineural hearing loss. After implantation, patients' speech recognition ability and quality of life have been significantly improved. The great success of cochlear implants has led to the rapid growth of the global hearing implant market. Despite the great success, the acoustic-electric converters of current cochlear implants are still placed outside the body, which brings many inconveniences to patients' daily lives: 1. The disabled appearance caused by the external acoustic-electric converter brings social pressure and psychological problems to patients; 2. The external acoustic-electric converter cannot be used during strenuous exercise, swimming, or sleeping; 3. The magnets used to fix the external acoustic-electric converter on the patient's head can cause pain or skin problems in the long run. Therefore, it is of great practical significance to solve the current problems of implanting cochlear implant acoustic-electric converters in the body.

[0003] The performance of implantable acoustic-to-electric transducers is required to be able to sensitively pick up external acoustic signals in the body, while avoiding internal noise as much as possible. In addition, problems such as biocompatibility and selection of implantation sites in the body must be solved. Previous studies have proposed that the middle ear cavity can be used as an implantation site in the body, but some sensors must remove the long process of the incus during the implantation process, which destroys the integrity of the original ossicular chain, increases the difficulty of implantation during surgery, and increases the weight of the ossicular chain. Previous literature has proposed the production of acoustic-to-electric transducers in the middle ear cavity using piezoelectric ceramic materials, but their effective working volume is large and requires more complex packaging, which is still very large for the narrow middle ear implantation cavity. Therefore, in summary, it is necessary to invent a new type of miniature implantable acoustic-to-electric transducer with a wide audio frequency bandwidth, good biocompatibility, and good plasticity. Summary of the invention

[0004] In response to the above technical problems, the present invention provides a modified P (VDF-TrFE) sensor and a preparation method thereof, which adopts a newly developed modified P (VDF-TrFE) material with excellent piezoelectric properties and frequency response performance. By utilizing a special curling method and combining it with a cantilever beam, the flexible material can fully improve the vibration conversion efficiency, and no active power supply is required, thereby reducing the signal noise introduced by direct current.

[0005] In order to achieve the above-mentioned purpose, the present invention provides a modified P (VDF-TrFE) sensor, comprising a flexible piezoelectric diaphragm, a cantilever arm and a clamping mechanism, wherein the cantilever arm is made of titanium alloy, implanted in the tympanic cavity of the middle ear and coupled with the neck of the malleus, the flexible piezoelectric diaphragm is made of a thin film piezoelectric material of vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE), the flexible piezoelectric diaphragm is flatly attached to the platform surface of the titanium alloy clamping mechanism, the flexible piezoelectric diaphragm is connected to the cantilever arm through silicone, and the other end is used to be fixed to the neck of the malleus.

[0006] Furthermore, the flexible piezoelectric membrane comprises a vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) film, the thickness of the film is 10 μm-500 μm, and platinum wires with a diameter of 0.05 mm are pasted on both sides of the film using conductive silver glue.

[0007] Furthermore, a graphene layer is provided on the upper surface of the film, and the thickness of the graphene layer is 10-100 μm.

[0008] Furthermore, the film is integrally packaged with MED-4211 silica gel, and the packaging thickness is 10-100 μm.

[0009] On the other hand, the present invention also provides a method for preparing a modified P (VDF-TrFE) sensor, comprising the following steps:

[0010] S1, preparing a vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) thin film piezoelectric material;

[0011] S2, preparing a multi-layer composite flexible piezoelectric film;

[0012] S3, preparation of stress structure and coupling structure of modified P(VDF-TrFE) sensor.

[0013] Furthermore, in step S1, it includes:

[0014] S101, reacting a ternary polymer P (VDF-TrFE) material with polyethyleneamine to form a vinylidene fluoride-trifluoroethylene polymer material;

[0015] S102, rinsing the vinylidene fluoride-trifluoroethylene polymer material with an organic solvent for multiple times, dissolving the material in a dimethylformamide solvent, and forming a film by a solution drying method;

[0016] S103, using a magnetron sputtering device to plate gold on both sides of the film as electrodes, and using conductive silver glue to bond a platinum wire with a diameter of 10 cm to each of the electrodes on both sides.

[0017] Furthermore, in step S2, it includes:

[0018] S201, using a vapor deposition method to form a 10 μm thick graphene layer on the upper surface of the flexible piezoelectric diaphragm;

[0019] S202, cutting the flexible piezoelectric film into a 2 mm wide rectangular sheet by low temperature laser cutting;

[0020] S203, using MED-4211 silica gel to encapsulate the flexible piezoelectric diaphragm as a whole, with a packaging thickness of 10 μm.

[0021] Furthermore, in step S3, it includes:

[0022] S301, using titanium alloy to make the main cantilever arm and clamping mechanism of the modified P (VDF-TrFE) sensor, the cantilever arm is a cylindrical structure, the long axis direction of which is parallel to the direction of the malleus, the clamping mechanism is vertically connected to one end of the cantilever arm, and the bottom of the clamping mechanism is connected and fixed to the neck of the malleus;

[0023] S302, connect the platinum wires on both sides of the diaphragm to two 0.05 mm silver wires as signal wires and ground wires respectively, and stick the flexible piezoelectric diaphragm flatly to the loading plane of the clamping mechanism.

[0024] The present invention has the following beneficial effects and technical advances:

[0025] 1. The fully implanted cochlear implant solves the patient's psychological burden on the appearance of wearing the implant and increases the patient's acceptance and willingness for cochlear implant surgery.

[0026] 2. The overall performance can be flexibly adjusted by adjusting the length of the cantilever arm and the overall elastic modulus of the composite piezoelectric material.

[0027] 3. The modified P (VDF-TrFE) material has low density and smaller volume. It not only reduces the difficulty of surgery, but also reduces the damping of the vibration system by the sensor's own weight.

[0028] 4. The modified P(VDF-TrFE) has better biocompatibility and durability. Existing literature reports that the materials in this design can achieve stable performance for decades, which is in line with the expected service life of the cochlear implant.

[0029] 5. Optimize circuit design. Compared with traditional sensors that require active functions, P (VDF-TrFE) sensors no longer require active power supply. They only need a ground wire and a signal wire to achieve signal recording, reducing line capacity, resulting in less surgical trauma and less impact on the physiological function of the sensor.

[0030] 6. Due to the reduction of active energy supply, the signal noise introduced by DC power is further reduced, the signal-to-noise ratio is improved, and the sensitivity of the system is enhanced.

[0031] 7. Tests show that the modified P (VDF-TrFE) sensor of the present invention has a wide frequency range of 20-20000Hz, which can cover all frequencies of human hearing, exceeding the previous traditional sensors. In particular, the frequency response curve in the low-frequency 100-1000Hz common speech frequency range performs well, which is better than traditional sensors and significantly improves the speech recognition quality when used by patients. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0033] Figure 1 It is a schematic structural diagram of a modified P (VDF-TrFE) sensor according to an embodiment of the present invention.

[0034] Figure 2 This is a flow chart of a method for preparing a modified P (VDF-TrFE) sensor according to an embodiment of the present invention. DETAILED DESCRIPTION

[0035] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0036] In order to better understand the above technical solution, exemplary embodiments of the present invention will be described in more detail below with reference to the accompanying drawings. Although exemplary embodiments of the present invention are shown in the accompanying drawings, it should be understood that the present invention can be implemented in various forms and should not be limited by the embodiments described herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present invention and to fully convey the scope of the present invention to those skilled in the art.

[0037] Figure 1 FIG. 1 is a schematic diagram of the structure of a modified P (VDF-TrFE) sensor according to an embodiment of the present invention. Figure 1 As shown, a modified P (VDF-TrFE) sensor according to an embodiment of the present invention includes a flexible piezoelectric membrane 1, a cantilever arm 2 and a clamping mechanism 3.

[0038] Preferably, in the present embodiment, the flexible piezoelectric diaphragm 1 is made of a vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) film, and gold is plated on both sides of the film as electrodes to form a capacitor. Conductive silver glue is used to adhere a platinum wire 4 with a length of 10 cm and a diameter of 0.05 mm on both sides of the film. At this time, the membrane material is subjected to vibration or direct pressure, and the dipoles move asymmetrically in the lattice, generating unevenly distributed charges, so that a voltage difference is formed on both sides of the membrane. The signal can be recorded by detecting the voltage of the two platinum wires, and the original vibration (sound) signal can be analyzed according to the phase change law and frequency law of the voltage. This is the basic principle of collecting sound signals using vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) material.

[0039] Preferably, the vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) diaphragm made in this embodiment needs to make a 10-100 μm thick graphene layer on the front to regulate the elastic modulus of the overall material so that it has better mechanical properties. The diaphragm is cut by low-temperature laser cutting to make a 2mm wide rectangular sheet. Finally, the diaphragm is packaged, and the MED-4211 silica gel of Nusil is used to package the material as a whole. The packaging thickness is 10-100 μm, and the packaging range includes the full length of the diaphragm and the platinum wire.

[0040] Preferably, a modified P (VDF-TrFE) sensor in this embodiment adopts a cantilever arm structure as a vibration amplification structure. The cantilever arm 2 is made of titanium alloy, the flexible piezoelectric diaphragm 3 is bonded to the cantilever arm 2 by silicone, one end of the clamping mechanism 3 is connected to the cantilever arm in a vertical direction, and the other end is provided with a clamping portion.

[0041] In this embodiment, the implantation position of the modified P(VDF-TrFE) sensor is the tympanic cavity of the middle ear, and the coupling position is the neck of the malleus. Because the main vibration direction of the malleus is the swing with the malleus head as the fulcrum, the cantilever arm structure formed by this fixing method can effectively transmit vibration, so that the piezoelectric material can convert vibration into electrical energy to a greater extent.

[0042] It should be noted that the piezoelectric performance of piezoelectric materials is mainly measured by parameters d33 and d31, 33 is the vertical direction of the largest plane of the rectangular piezoelectric element, and 11 is the long axis direction. The vibration in the 33 direction has the largest force conversion, which can be calculated by the d33 value. The use of the 11 direction needs to be based on the cantilever arm, a boundary constraint condition with one end fixed and the other end swinging freely. In this swinging mode, the two sides of the piezoelectric sheet will form compressive stress and tensile stress due to bending, so as to generate charge movement through deformation in the 11 direction. The results of the three-dimensional reconstruction finite element analysis confirmed that under the same size specifications of piezoelectric sensors, the coupling method of the cantilever beam structure with a 90-degree angle is better than adhesive fixation and mesh wrapping fixation. The results of animal experiments are also consistent with the above conclusions.

[0043] This embodiment uses reasonable finite element simulation design to superimpose the aforementioned diaphragm structure and its coating on the metal substrate of the cantilever beam by utilizing the characteristics of its flexible material. At this time, the diaphragm structure changes from a two-dimensional plane to a three-dimensional curled and harmonically variable structure, which has the initial internal stress and greatly improves its vibration amplification performance.

[0044] Through the setting of the above-mentioned piezoelectric sheet and the modified P (VDF-TrFE) sensor, the present invention does not need external power supply, and only needs one ground wire and one signal wire to realize signal recording, thereby reducing the line capacity, thereby reducing the surgical trauma and reducing the impact on the physiological function of the body.

[0045] Figure 2 FIG. 1 is a flow chart of a method for preparing a modified P (VDF-TrFE) sensor according to an embodiment of the present invention. Figure 2 As shown, a method for preparing a modified P (VDF-TrFE) sensor of the present invention comprises the following steps:

[0046] S1, preparing vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) thin film piezoelectric material.

[0047] Specifically, in the preparation process, a special ternary polymer P(VDF-TrFE) material is first used to react with polyethyleneamine for several hours to form poly(vinylidene fluoride-trifluoroethylene) P(VDF-TrFE) material, which is then rinsed with an organic solvent for multiple times and dissolved in a DMF solution. The film is made into a thin film by a solution drying method, and the film thickness can be freely adjusted between 10μm-500μm according to the elastic modulus and voltage requirements described later. The film is mechanically stretched to increase the β-phase content to improve its piezoelectric properties.

[0048] S2, preparing a multi-layer composite flexible piezoelectric membrane.

[0049] Specifically, after the preparation of the vinyl fluoride-trifluoroethylene polymer P (VDF-TrFE) thin film piezoelectric material is completed, a 10-100 μm graphene layer is produced on the upper and lower surfaces of the film using a vapor deposition method to regulate the elastic modulus of the overall material so that it has better mechanical properties.

[0050] In this embodiment, after the surface preparation is completed, cutting and packaging operations are performed. The cutting is performed using a low-temperature laser to cut the flexible piezoelectric diaphragm into 2 mm wide long strips. Finally, Nusil's MED-4211 silica gel is used to package the material as a whole, with a packaging thickness of 10-100 μm, and the packaging range includes the diaphragm and platinum wire.

[0051] S3, preparation of stress structure and coupling structure of modified P(VDF-TrFE) sensor.

[0052] Specifically, the cantilever arm structure of the sensor is first made, and the cantilever arm and the clamping mechanism are made of titanium alloy. The cantilever arm is a cylindrical structure, and its long axis direction is parallel to the direction of the malleus. The clamping mechanism is vertically connected to one end of the cantilever arm, and the bottom of the clamping mechanism is connected and fixed to the neck of the malleus. The flexible piezoelectric diaphragm is wound on the cantilever arm, and the platinum wires on both sides of the diaphragm are connected to the signal line and the ground line respectively.

[0053] Although the embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and cannot be understood as limiting the present invention. A person of ordinary skill in the art can change, modify, replace and modify the above embodiments within the scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A modified P (VDF-TrFE) sensor, characterized in that: It includes a flexible piezoelectric diaphragm, a cantilever arm and a clamping mechanism. The cantilever arm is made of titanium alloy, implanted in the tympanic cavity of the middle ear and coupled with the neck of the malleus. The flexible piezoelectric diaphragm is made of a thin film piezoelectric material of vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE), and the flexible piezoelectric diaphragm is connected to the cantilever arm through silicone. One end of the clamping mechanism is connected to the cantilever arm, and the other end is used to fix to the neck of the malleus.

2. A modified P (VDF-TrFE) sensor as claimed in claim 1, characterized in that: The flexible piezoelectric membrane comprises a vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) film, the thickness of the film is 10 μm-500 μm, and conductive silver glue is used to adhere platinum wires with a diameter of 0.05 mm on both sides of the film.

3. A modified P (VDF-TrFE) sensor as claimed in claim 2, characterized in that: A graphene layer is provided on the upper surface of the film, and the thickness of the graphene layer is 100-200 μm.

4. A modified P (VDF-TrFE) sensor as claimed in claim 3, characterized in that: The film is packaged as a whole using MED-4211 silica gel, and the packaging thickness is 10-100 μm.

5. A method for preparing a modified P (VDF-TrFE) sensor, characterized in that: The following steps are involved: S1, preparing a vinylidene fluoride-trifluoroethylene polymer P (VDF-TrFE) thin film piezoelectric material; S2, preparing a multi-layer composite flexible piezoelectric film; S3, preparation of stress structure and coupling structure of modified P(VDF-TrFE) sensor.

6. The method for preparing a modified P (VDF-TrFE) sensor according to claim 5, characterized in that: In step S1, it includes: S101, reacting a ternary polymer P (VDF-TrFE) material with polyethyleneamine to form a vinylidene fluoride-trifluoroethylene polymer material; S102, rinsing the vinylidene fluoride-trifluoroethylene polymer material with an organic solvent for multiple times, dissolving the material in a dimethylformamide solvent, and forming a film by a solution drying method; S103, gold was plated on both sides of the film as electrodes using a magnetron sputtering apparatus, and a platinum wire with a length of 10 cm and a diameter of 0.05 mm was bonded to each side of the film using a conductive silver glue.

7. The method for preparing a modified P (VDF-TrFE) sensor according to claim 6, characterized in that: In step S2, it includes: S201, using a vapor deposition method to form a graphene layer with a thickness of 10-100 μm on the upper surface of the flexible piezoelectric diaphragm; S202, cutting the flexible piezoelectric film into a 2 mm wide rectangular sheet by low temperature laser cutting; S203, using MED-4211 silica gel to encapsulate the flexible piezoelectric diaphragm as a whole, with the encapsulation thickness being 10-100 μm.

8. The method for preparing a modified P (VDF-TrFE) sensor according to claim 7, characterized in that: In step S3, it includes: S301, using titanium alloy to make the main cantilever arm and clamping mechanism of the modified P (VDF-TrFE) sensor, the cantilever arm is a cylindrical structure, the long axis direction of which is parallel to the direction of the malleus, the clamping mechanism is vertically connected to one end of the cantilever arm, and the bottom of the clamping mechanism is connected and fixed to the neck of the malleus; S302, winding the flexible piezoelectric diaphragm on the cantilever arm, and connecting the platinum wires on both sides of the diaphragm to the signal wire and the ground wire respectively.

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