Intelligent dental implant, and its surrounding microenvironment pH value data acquisition method and system

Abstract

The application discloses an intelligent dental implant, a method and a system for acquiring pH value data of a microenvironment around the intelligent dental implant. The intelligent dental implant comprises an implant body, an abutment, a dental crown and a passive LC resonance pH sensor. The passive LC resonance pH sensor is arranged at a neck portion of the abutment and comprises a spiral inductor coil, a variable capacitor and a flexible substrate. A dielectric layer of the variable capacitor is a pH-sensitive hydrogel. The volume of the hydrogel changes under different pH environments, the change of water content of the hydrogel leads to a significant change of a dielectric constant, thereby changing a capacitance value, and further causing a resonance frequency of an LC resonance loop to be offset. An external reader provides excitation energy to the passive LC resonance pH sensor through inductive coupling. After receiving the resonance frequency signal, a data processing module completes conversion according to a pre-established corresponding relationship between the pH value and the resonance frequency. The passive LC resonance sensing technology is integrated in the neck portion of the abutment, and the passive data acquisition process of the pH value of the gingival crevicular fluid around the implant is realized without additional trauma and in-situ acquisition.

Description

Technical Field

[0001] This application relates to the field of oral implant and restoration technology, specifically to an intelligent dental implant, a method and system for acquiring pH data of its surrounding microenvironment. Background Technology

[0002] Dental implants have become one of the most mainstream methods for restoring missing teeth, occupying an important position in the field of dental implant restoration. With the increasing emphasis on oral health, higher demands are being placed on the performance of dental implants and related monitoring technologies. Changes in the microenvironment of the tissues surrounding the implant are a crucial factor affecting the long-term stability of the implant, and the pH value of the peri-implant gingival crevicular fluid is one of the important physicochemical parameters reflecting the state of the peri-implant microenvironment. Accurately obtaining this pH value data helps in timely understanding the microenvironment status around the implant, which is of great significance for ensuring the long-term stability of the implant and oral health.

[0003] Existing pH measurement methods mainly include invasive paper point sampling and active sensor methods. Invasive paper point sampling involves inserting a standard paper point into the gingival sulcus to collect gingival crevicular fluid samples, followed by in vitro analysis using a benchtop pH meter. This method requires relatively complex procedures, including sampling, sample transfer, and analysis using benchtop equipment. Active sensor methods enable wireless monitoring. They operate by using built-in batteries or other active components to power the sensor, thereby achieving pH monitoring and data transmission.

[0004] However, existing pH measurement methods have certain limitations. Invasive paper-point sampling is complex to operate and cannot continuously monitor the pH of the microenvironment surrounding the implant, failing to reflect dynamic changes in the microenvironment in a timely manner. While active sensor methods enable wireless monitoring, they suffer from large battery sizes, which may affect the overall structure of the dental implant and the user experience. Furthermore, they present the inconvenience of periodic battery replacements and risks such as leakage and heat generation. Moreover, there is currently no technology to precisely integrate passive wireless sensing technology into the dental implant abutment for in-situ acquisition of pH data specific to the gingival crevicular fluid microenvironment. Summary of the Invention

[0005] To address the technical problems in the prior art, this application provides a smart dental implant, a method and system for acquiring pH data of its surrounding microenvironment.

[0006] The technical solution provided in this application for a smart dental implant, a method and system for acquiring pH data of its surrounding microenvironment, is as follows:

[0007] A smart dental implant, comprising:

[0008] The implant itself;

[0009] A base, which is connected to the implant body;

[0010] A crown, which is mounted on top of the abutment;

[0011] A passive LC resonant pH sensor is disposed at the neck of the base. The passive LC resonant pH sensor includes a spiral inductor, a variable capacitor, and a flexible substrate. The spiral inductor receives energy from an external alternating magnetic field to excite the LC resonant circuit and reflects the resonant frequency signal of the LC resonant circuit to the outside via inductive coupling. The variable capacitor includes two parallel metal electrodes and a pH-sensitive hydrogel dielectric layer sandwiched between the two parallel metal electrodes. The pH-sensitive hydrogel dielectric layer undergoes volume changes under different pH environments, and the change in the water content of the hydrogel leads to a significant change in the dielectric constant, thereby changing the capacitance value of the variable capacitor. The flexible substrate is a flexible thin film used to support the spiral inductor and the variable capacitor.

[0012] The spiral inductor and the variable capacitor are electrically connected to form an LC resonant circuit. When the pH value of the liquid in contact with the pH-sensitive hydrogel dielectric layer changes, the capacitance value of the variable capacitor changes accordingly, causing the resonant frequency of the LC resonant circuit to shift.

[0013] A method for acquiring pH data of the microenvironment surrounding a smart dental implant, using the aforementioned smart dental implant, includes the following steps:

[0014] S1. Bring the external reader close to the oral cavity area where the intelligent dental implant is installed. The magnetic field emitting module in the external reader emits an alternating magnetic field to the passive LC resonant pH sensor, providing excitation energy to the passive LC resonant pH sensor through inductive coupling.

[0015] S2. The passive LC resonant pH sensor reflects a signal at its current resonant frequency, and the signal receiving module in the external reader receives the reflected signal and measures the resonant frequency value.

[0016] S3. The data processing module converts the measured resonant frequency value into a pH value according to the pre-established correspondence between pH value and resonant frequency. The correspondence is established point by point by using a standard pH buffer before the passive LC resonant pH sensor leaves the factory and is stored in the memory of the data processing module.

[0017] S4. Output the pH value to a display terminal or storage medium to generate microenvironment physicochemical parameter data records.

[0018] A smart system for acquiring pH data of the microenvironment around dental implants, comprising:

[0019] The aforementioned intelligent dental implant; and

[0020] An external reader, comprising a magnetic field emitting module and a signal receiving module, wherein the magnetic field emitting module includes a transmitting coil for emitting an alternating magnetic field to the passive LC resonant pH sensor to provide excitation energy through inductive coupling; and the signal receiving module includes a receiving coil for receiving the resonant frequency signal reflected by the passive LC resonant pH sensor; and

[0021] The data processing module includes a processor and a memory storing calibration curves. The processor is used to convert the received resonant frequency signal into a pH value according to a pre-established correspondence between pH value and resonant frequency, and output the pH value to a display terminal or storage medium.

[0022] A method for synthesizing a pH-sensitive hydrogel dielectric layer for use in the intelligent dental implant, comprising the following steps:

[0023] Step 1, Monomer preparation: Dissolve acrylic acid and acrylamide in deionized water at a mass ratio of 7:3 to prepare a solution with a total monomer concentration of 10-20 wt%. Add crosslinking agent N,N'-methylenebisacrylamide, with the amount of MBA being 0.1-0.5 wt% of the total monomer mass. Stir magnetically until completely dissolved.

[0024] Step 2, Initiator addition: After purging N2 into the solution obtained in Step 1 to remove oxygen for 20-40 min, add the ammonium persulfate / sodium bisulfite redox initiator system, each accounting for 0.3-0.8 wt% of the total monomer mass, and continue stirring until homogeneous;

[0025] Step 3, polymerization reaction: The mixture obtained in step 2 is injected into a thickness-controlled mold and reacted in a water bath at 60-70°C for 4-6 hours to complete the polymerization; or the polymerization is initiated by ultraviolet light with a wavelength of 365 nm and a light intensity of 8-12 mW / cm² for 30-60 minutes to obtain a hydrogel film.

[0026] Step 4, purification and drying: Soak the hydrogel obtained in step 3 in deionized water for 60-80 h, changing the water every 10-14 h to remove unreacted monomers and initiator residues, and then vacuum dry at 35-45°C to constant weight to obtain a dry gel film;

[0027] Step 5, Activation and Thickness Control: Soak the dry gel film obtained in Step 4 in PBS buffer at pH 7.4 for 20–28 h to allow it to fully swell, then spin-coat or calender it to the target thickness of 50–200 μm, and dry it under sterile conditions for later use.

[0028] In summary, this application includes at least one of the following beneficial technical effects:

[0029] 1. The passive LC resonant pH sensor is integrated into the neck of the abutment and obtains excitation energy from an external reader through inductive coupling. The passive LC resonant pH sensor itself does not require a built-in battery, which overcomes the shortcomings of active sensors such as large battery size, need for regular replacement, and risk of leakage and heat generation. At the same time, the passive LC resonant pH sensor is directly deployed in the gingival crevicular fluid contact area, and the data acquisition process does not require sampling and transfer operations. The entire data acquisition process does not cause additional trauma to the implant and surrounding tissues.

[0030] 2. A polyacrylic acid-co-acrylamide copolymer hydrogel with an acrylic acid to acrylamide mass ratio of 7:3 is used as the dielectric layer of the variable capacitor. The volume change rate is greater than 200% within the pH range of 4–8, and the capacitance change rate is greater than 150% when the pH drops from 7.0 to 5.5. The passive LC resonant pH sensor exhibits a sensitivity of no less than 5% frequency shift per pH unit within the clinically critical pH range of 5.5–7.0 (i.e., a resonant frequency shift of no less than 2.5% when the pH changes by 0.5 units). This sensitivity is sufficient to distinguish between a healthy state (pH 6.5–7.0) and an early peri-implantitis state (pH 5.5–6.5). Compared to invasive paper tip sampling methods that only allow for single-detection, this method enables continuous monitoring of the microenvironment's pH value, promptly reflecting dynamic changes in the microenvironment.

[0031] 3. A complete synthesis process for pH-sensitive hydrogel dielectric layers is provided. By controlling the mass ratio of acrylic acid to acrylamide and the amount of crosslinking agent, the pH response sensitivity and mechanical strength of the hydrogel can be adjusted. The entire synthesis process does not require organic solvents and is green and environmentally friendly. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the overall structure of an intelligent dental implant provided in an embodiment of this application; it shows the overall layout of the implant body 1, abutment 2, passive LC resonant pH sensor 3, gingival crevicular fluid contact area 21, crown 4 and external reader 5. The external reader 5 shows the multi-turn transmitting coil structure of the magnetic field transmitting module 51 and the receiving coil structure of the signal receiving module 52, as well as the working diagram of the magnetic field transmitting module 51 transmitting an alternating magnetic field to the passive LC resonant pH sensor 3 and the signal receiving module 52 receiving the reflected signal;

[0033] Figure 2 yes Figure 1A partial enlarged view of the passive LC resonant pH sensor 3 at the neck of the middle base 2; it shows the multilayer thin film structure of the passive LC resonant pH sensor 3, which consists of, from the outside to the inside, a Parylene-C waterproof coating 34, a variable capacitor 32 (facing the liquid environment on the outside), a spiral inductor coil 31, and a flexible substrate 33 (attached to the surface side of the base 2), with an adhesive fixing layer 35 located between the flexible substrate 33 and the base 2;

[0034] Figure 3 This is a schematic diagram of the passive LC circuit of this application; it shows the parallel connection relationship of the inductor L and the variable capacitor C, and the formula for the resonant frequency is marked.

[0035] Figure 4 This is a flowchart of the inductive coupling data acquisition process of the external reader 5 in this application; it shows the complete data acquisition process from the magnetic field emitting module 51 emitting a magnetic field, the passive LC resonant pH sensor 3 reflecting a frequency signal, the signal receiving module 52 measuring the resonant frequency, the data processing module performing frequency-pH value conversion, to the final pH value output to the display terminal or storage medium;

[0036] Figure 5 This is a schematic diagram of the pH response curve of this application; the horizontal axis is the pH value, the vertical axis is the resonant frequency f0, and the curve has an S-shaped feature, showing the frequency change law in the low pH region, the transition region and the high pH region.

[0037] Figure 6 This is a flowchart of the pH-sensitive hydrogel synthesis process of this application; it shows the complete process flow from step one monomer preparation (AA+AM+MBA), step two deoxygenation and initiator addition with N2, step three polymerization reaction (65°C / 5h or UV), step four purification and drying (washing with water for 72h + vacuum) to step five activation and thickness control (PBS + 150μm), as well as the chemical process of AA and AM monomers crosslinking with MBA to form a crosslinked network structure;

[0038] Figure 7 This is a comparison curve of pH response of different hydrogel formulations; where H1, H2, H3, and H4 represent hydrogel formulations with different monomer ratios or degrees of crosslinking, the horizontal axis is the pH value (range 0-12), the vertical axis is the swelling ratio, and the four curves show the differences in swelling response of different formulations under pH changes.

[0039] Figure labeling: 1. Implant body; 2. Abutment; 21. Gingival crevicular fluid contact area; 3. Passive LC resonant pH sensor; 31. Helical inductor coil; 32. Variable capacitor; 33. Flexible substrate; 34. Parylene-C waterproof coating; 35. Adhesive fixation layer; 4. Crown; 5. External reader; 51. Magnetic field transmitting module; 52. Signal receiving module; 6. Alveolar bone. Detailed Implementation

[0040] The technical solutions in the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. The described embodiments are only possible technical implementations of the present invention, but are not limited thereto. Other embodiments obtained by those skilled in the art in conjunction with the embodiments of the present invention without creative effort are also within the protection scope of the present invention.

[0041] This application mainly adopts a solution of integrating sensors into the dental implant abutment to passively acquire pH data, achieving the effect of passive, non-invasive, and in-situ acquisition of pH data of the microenvironment around the implant. The following is a further detailed description of this application.

[0042] In this application, "neck of abutment" refers to the section of abutment 2 that is in contact with the soft tissue surrounding the implant, that is, the part of abutment 2 exposed to the gingiva or adjacent to the soft tissue surrounding the implant. This section is the first point of contact for gingival crevicular fluid and is also the location where the passive LC resonant pH sensor 3 is set.

[0043] Example 1

[0044] Please refer to Figures 1 to 3 The intelligent dental implant provided in this application includes an implant body 1, an abutment 2, a crown 4, and a passive LC resonant pH sensor 3. The implant body 1 is connected to the abutment 2, and the crown 4 is mounted above the abutment 2. The passive LC resonant pH sensor 3 is located in the gingival crevicular fluid contact area 21 at the neck of the abutment 2. After the abutment 2 is implanted, the outer surface of the passive LC resonant pH sensor 3 (i.e., the exposed surface of the pH-sensitive hydrogel dielectric layer) faces the gingival sulcus and is directly immersed in the gingival crevicular fluid. The height of the gingival crevicular fluid contact area 21 is 1-3 mm. With this structural arrangement, when the pH value of the liquid in contact with the passive LC resonant pH sensor 3 changes, the resonant frequency of the LC resonant circuit can be altered, thereby enabling monitoring of the pH value of the microenvironment surrounding the implant. This passive design avoids the battery-related risks associated with active sensors and allows for in-situ data acquisition, ensuring data accuracy and timeliness.

[0045] Specifically, the implant body 1 is implanted into the alveolar bone 6. The implant body 1 typically uses a threaded titanium alloy structure, which facilitates stable implantation into the alveolar bone, functioning as an artificial tooth root. Commercially available standard titanium alloy implants are all acceptable. Titanium alloy is chosen as the material for the implant body 1 because it has good biocompatibility, reducing the risk of rejection by the body, while also possessing sufficient strength to support the subsequently installed abutment 2 and crown 4.

[0046] The abutment 2 is fixedly connected to the implant body 1 with screws. During connection, the screw torque needs to be carefully controlled, generally between 15-35 N·cm, to ensure a stable connection. The abutment 2 can be made of titanium alloy or zirconia, both of which have good compatibility with the implant body 1 and the crown 4, and meet the requirements for use in the oral cavity. After installation, a temporary healing cap can be used to protect the area of ​​the passive LC resonant pH sensor 3. The permanent crown 4 will be installed after the surrounding soft tissue has stabilized.

[0047] The crown 4 is installed above the abutment 2. Its main function is to restore the tooth's chewing function and aesthetic appearance. The material and shape of the crown 4 can be customized according to the patient's specific needs and oral condition to achieve the best performance and aesthetics.

[0048] Please refer to Figure 2 The passive LC resonant pH sensor 3 includes a spiral inductor coil 31, a variable capacitor 32, and a flexible substrate 33. Figure 2 The image clearly shows the multilayer thin-film structure of the passive LC resonant pH sensor 3. From the outside in, it consists of a Parylene-C waterproof coating 34, a variable capacitor 32 (facing the liquid environment), a spiral inductor coil 31, and a flexible substrate 33 (in this embodiment, the flexible substrate 33 is a polyimide flexible substrate, which adheres to the surface of the base 2). An adhesive fixing layer 35 is located between the flexible substrate 33 and the base 2. The spiral inductor coil 31 is generally made of conductive materials such as Cu or Ag. These materials have good conductivity and can effectively receive external alternating magnetic field energy to excite the LC resonant circuit, and reflect the resonant frequency signal of the LC resonant circuit to the outside through inductive coupling. The spiral inductor coil 31 has 5-10 turns, a diameter of 2-4 mm, and a line width of 0.10-0.20 mm. For example, in some practical applications, the spiral inductor coil 31 uses an 8-turn design with a diameter of 3 mm and a line width of 0.15 mm. This design can ensure the signal reception and reflection effect without occupying too much space.

[0049] The variable capacitor 32 includes two parallel metal electrodes and a pH-sensitive hydrogel dielectric layer sandwiched between them. The pH-sensitive hydrogel dielectric layer is made of polyacrylic acid-co-acrylamide copolymer hydrogel, wherein the mass ratio of acrylic acid to acrylamide is 7:3, and the crosslinking agent is N,N'-methylenebisacrylamide. This hydrogel is synthesized via free radical solution polymerization. The acrylic acid monomer provides the pH-sensitive carboxyl groups, the acrylamide monomer provides the mechanical strength, and the crosslinking agent is used at 0.1-0.5 wt% of the total monomer mass. The thickness of the pH-sensitive hydrogel dielectric layer is 50-200 μm, for example, 150 μm in this embodiment. When the pH value of the liquid in contact with the pH-sensitive hydrogel dielectric layer changes, the hydrogel undergoes a volume change, thereby altering the capacitance value of the variable capacitor 32. Specifically, when the pH decreases, the carboxyl groups (-COOH) in the hydrogel undergo protonation, and the conformational change of the polymer chains causes the hydrogel to absorb water and swell. The increased water content significantly increases the dielectric constant (from about 3-5 in the dry state to about 30-60 in the hydrated state). Although the distance between the two electrodes increases slightly at the same time, the increase in dielectric constant far outweighs the effect of the increased distance. The net effect is an increase in capacitance C and a decrease in resonant frequency f0. Conversely, when the pH increases, the carboxyl groups deprotonate, the hydrogel loses water and shrinks, the dielectric constant decreases, the capacitance C decreases, and the resonant frequency f0 increases.

[0050] Please refer to Figure 3 The spiral inductor coil 31 (inductance value L) and the pH-sensitive hydrogel variable capacitor 32 (capacitance value C) form an LC resonant circuit. Figure 3 The parallel connection of inductor L and variable capacitor C is shown. The resonant frequency f0 is determined by the following formula:

[0051]

[0052] When the pH of the liquid in contact with the passive LC resonant pH sensor 3 decreases, the carboxyl groups (-COOH) in the hydrogel undergo protonation, and the conformational change of the polymer chain causes the hydrogel to absorb water and swell. The increased water content significantly increases the dielectric constant (from about 3-5 in the dry state to about 30-60 in the hydrated state). Although the distance between the two electrodes increases slightly at the same time, the increase in dielectric constant far outweighs the effect of the increased distance. The net effect is an increase in capacitance C and a corresponding decrease in resonant frequency f0. Conversely, when the pH increases, the carboxyl groups deprotonate, the hydrogel loses water and shrinks, the dielectric constant decreases, the capacitance C decreases, and the resonant frequency f0 increases. In this embodiment, the pH data acquisition range of the passive LC resonant pH sensor 3 is 4-8, the sensitivity is greater than 5% offset / pH unit, and the capacitance change rate is greater than 150% when the pH decreases from 7.0 to 5.5.

[0053] The maximum reading distance of the passive LC resonant pH sensor 3 is 5-15 mm (depending on the number of turns and diameter of the spiral inductor coil 31). When the transmitting coil of the external reader 5 is close to the oral mucosa surface, the distance between the two coils is approximately 3-8 mm. At this distance, the coupling coefficient k is approximately 0.01-0.05, and the signal strength meets the reading requirements. The titanium alloy implant body 1 is made of non-ferromagnetic material and will not produce a significant shielding effect on the alternating magnetic field in the 13.56 MHz frequency band.

[0054] Accelerated aging experiments in an artificial saliva environment at 37°C showed that the passive LC resonant pH sensor 3 exhibited a baseline drift of less than 2% in resonant frequency and a pH measurement deviation of less than 0.3 pH units after 6 months of continuous immersion, meeting the accuracy requirements for clinical monitoring. The Parylene-C waterproof coating 34 effectively prevented protein penetration into the helical inductor coil 31 and electrodes, maintaining the stability of the circuit's electrical performance. The pH-sensitive hydrogel dielectric layer, being directly exposed to gingival crevicular fluid, experienced a decrease in pH response sensitivity of approximately 15-20% after 6 months; this drift could be compensated for through recalibration.

[0055] The flexible substrate 33 is a polyimide film with a thickness of 25-50 μm, for example, 35 μm in this embodiment. The polyimide film exhibits good flexibility and stability, effectively supporting the spiral inductor coil 31 and the variable capacitor 32. A Parylene-C waterproof coating 34, with a thickness of 5-10 μm, is formed on the outer surface of the passive LC resonant pH sensor 3, avoiding the liquid contact surface of the pH-sensitive hydrogel dielectric layer. For example, in this embodiment, it is formed by vapor deposition with a thickness of 8 μm. The Parylene-C waterproof coating 34 prevents intraoral liquids from damaging the circuitry of the passive LC resonant pH sensor 3, extending its lifespan. The Parylene-C material has obtained full FDA and ISO 10993 certifications, exhibits a L929 fibroblast survival rate greater than 95%, and has low surface energy (contact angle less than 60°), effectively inhibiting non-specific protein adsorption and initial bacterial attachment.

[0056] The passive LC resonant pH sensor 3 is fixed to the neck of the abutment 2 via either a wrapping or adhesive fixation. In the wrapping fixation method, the passive LC resonant pH sensor 3 is cut into a strip of 18mm × 1.5mm and wrapped 1.5 times around the neck of the abutment 2, with the pH-sensitive hydrogel dielectric layer facing away from the abutment 2, i.e., towards the soft tissue surrounding the implant, directly exposed to the external liquid environment. Then, a UV-curable dental adhesive (such as Panavia) is applied to the edges to form an adhesive fixation layer 35 (less than 0.1mm thick). After UV curing, a Parylene-C waterproof coating 34 is vapor-deposited onto the entire structure. The passive LC resonant pH sensor 3 can cover the buccal, lingual, mesial, and distal sides, ensuring omnidirectional data acquisition. This fixation method is suitable for most commercial abutments 2, is easy to operate, and ensures a tight fit between the passive LC resonant pH sensor 3 and the neck of the abutment 2, guaranteeing sufficient contact with the external liquid environment and accurate data acquisition. The passive design eliminates battery-related risks, increases volume by less than 0.5 mm, and does not affect the normal function of the base station 2.

[0057] In the adhesive fixation method, the passive LC resonant pH sensor 3 is fabricated into an arc-shaped patch and adhered to the neck of the abutment 2. A UV-curable dental adhesive (such as RelyX Ultimate) is used to form an adhesive fixation layer 35 for bonding and fixation. After light pressure for 60 seconds, it is cured by UV light irradiation. The arc curvature radius of the adhesive passive LC resonant pH sensor 3 is pre-customized according to the diameter of the neck of the abutment 2, typically 2-3 mm, to ensure a tight fit. Adhesive fixation is particularly suitable for abutments with smooth necks, is easier to operate, and is suitable for mass production. Although the sensitivity is reduced by about 10% compared to the wrap-around method, the mechanical stability is improved, making it less prone to detachment during long-term use. Both the wrap-around and adhesive fixation methods described above use an adhesive fixation layer 35 to bond the passive LC resonant pH sensor 3 to the neck of the abutment 2. The material of the adhesive fixation layer 35 is a UV-curable dental adhesive.

[0058] Furthermore, the base 2 can also be manufactured using a 3D printing one-piece molding process, and the material can be SLM titanium alloy or FDMPEEK. A microgroove with a depth of 0.2-0.5 mm is pre-reserved in the neck of the base 2 (e.g., 0.3 mm in this embodiment). The passive LC resonant pH sensor 3 is embedded in this microgroove, and then resin is drip-coated to fill the gaps in the microgroove to fix the passive LC resonant pH sensor 3. After polishing, a Parylene-C coating (10 μm thickness) is applied. 3D printing can be performed using a selective laser melting device such as the EOS M290, with a printing layer thickness of 20-40 μm. After printing, heat treatment is performed to eliminate residual stress. The dimensional accuracy of the microgroove can be controlled within ±0.05 mm. This 3D printing integrated molding method eliminates the adhesive interface between the passive LC resonant pH sensor 3 and the abutment 2, significantly improving mechanical reliability and long-term stability. The mechanical fatigue strength meets the ISO 14801 standard (no loosening after 106 cycles). The pre-reserved microgroove design allows the passive LC resonant pH sensor 3 to be completely embedded in the surface of the abutment 2 without increasing the outer diameter of the abutment 2 or affecting the accuracy of the connection between the implant body 1 and the abutment 2, making it particularly suitable for mass production. The embedded microgroove fixing method in this embodiment is a third fixing scheme, distinct from the aforementioned winding and adhesive fixing methods. By completely embedding the passive LC resonant pH sensor 3 into the pre-reserved microgroove on the surface of the abutment 2, the method eliminates the adhesive interface by filling with resin, without requiring an additional adhesive fixing layer 35.

[0059] The passive LC resonant pH sensor 3 has a surface roughness Ra of 0.2-0.5 μm in contact with the external liquid. Its surface facing the external soft tissue is activated by O2 plasma to introduce hydrophilic groups. Specifically, the surface of the passive LC resonant pH sensor 3 facing the external soft tissue is activated by O2 plasma (50 W, 30 s) to introduce hydrophilic groups (-OH, -COOH), reducing the contact angle to less than 30°. This O2 plasma activation treatment is performed after the passive LC resonant pH sensor 3 is assembled with the abutment 2 but before implantation; or immediately after plasma treatment, the hydrophilic groups are permanently fixed by chemical grafting (e.g., modification with aminosilane coupling agents SAMs) to prevent the hydrophilicity from decaying over time due to the aging effect. The surface roughness Ra is precisely controlled within the range of 0.2-0.5 μm, which is the "bio-friendly window" most favorable for the attachment of epithelial cells and fibroblasts. The surface roughness can be achieved through laser micromachining or nanoimprinting and characterized by atomic force microscopy (AFM) or white light interferometry. Through this optimization process, the passive LC resonant pH sensor 3 can form a biological seal with the surrounding soft tissue. This biological seal includes hemidesmosomes formed by epithelial cells on the surface of the passive LC resonant pH sensor 3 and type I collagen fiber bundles attached by fibroblasts. After installation, epithelial cells can migrate to the surface of the passive LC resonant pH sensor 3, forming hemidesmosomes and basement membrane-like structures at the contact interface; connective tissue fibroblasts produce type I collagen fiber bundles, forming a biological seal with the surface of the passive LC resonant pH sensor 3. This process is usually completed within 4-8 weeks, forming a physical-biological dual barrier. This biological seal effectively blocks bacterial invasion, maintains a good tissue interface, and also maintains the long-term stability of the passive LC resonant pH sensor 3 signal, avoiding signal drift caused by liquid leakage.

[0060] There are differences between conventional and intelligent abutments in terms of soft tissue sealing: conventional abutments have smooth surfaces, resulting in poor soft tissue sealing and gaps that allow for easy bacterial invasion; intelligent abutments, after surface optimization treatment, allow epithelial cells and fibroblasts to adhere well to the surface of the passive LC resonant pH sensor 3, forming a stable biological seal and effectively blocking bacterial invasion. Animal model (Beagle dogs) validation showed that the sensor group using the surface treatment of this application achieved a soft tissue adhesion length of 1.8-2.2 mm, a histological score that was more than 60% lower than the control group, and a bacterial penetration rate of less than 5%.

[0061] Please refer to Figure 5The pH response curve exhibits an S-shaped characteristic: the resonant frequency is high and stable in the pH range of 6.5-7.0; the frequency begins to decrease significantly in the pH range of 6.0-6.5; and the frequency drops sharply below pH 6.0. This non-linear response characteristic enables the passive LC resonant pH sensor 3 to have higher sensitivity in the critical pH range of 5.5-7.0.

[0062] Please refer to Figure 6 The pH-sensitive hydrogel dielectric layer was synthesized using a free radical solution polymerization method. Figure 6 The diagram shows the complete process flow from monomer formulation to the final product. The specific synthesis steps are as follows:

[0063] Step 1, Monomer Preparation: Dissolve acrylic acid (AA) and acrylamide (AM) in deionized water at a mass ratio of 7:3 (total monomer concentration 15wt%). Add the crosslinking agent N,N'-methylenebisacrylamide (MBA, accounting for 0.3wt% of the total monomer mass). Stir magnetically for 30 min until completely dissolved. Adjust the pH of the solution to 4.5-5.0. A magnetic stirrer with a heating plate can be used during stirring, and the temperature should be controlled at room temperature (25°C).

[0064] Step 2, Initiator addition: After purging with N2 for 30 min to remove oxygen, add the ammonium persulfate (APS) / sodium bisulfite (SBS) redox initiator system (each accounting for 0.5 wt% of the total monomer mass), and continue stirring for 10 min.

[0065] Step 3, polymerization reaction: The mixture is injected into a mold with a glass plate gap thickness controlled at 150 μm, and polymerization is completed by reacting in a 65°C water bath for 5 h. An alternative method is to use UV photoinitiation (365 nm, 10 mW / cm², 45 min). A constant temperature water bath can be used for water bath heating, with temperature accuracy controlled within ±1°C. A 365 nm UV lamp can be used for UV photoinitiation, and the light intensity is calibrated using a radiometer.

[0066] Step 4, post-processing purification: After the reaction is complete, the gel is soaked in deionized water for 72 h (the water is changed every 12 h) to remove unreacted monomers and initiator residues; then it is dried in a vacuum drying oven at 40°C for 24 h to constant weight to obtain a dry gel film.

[0067] Step 5, Activation and Thickness Control: Immerse the dried gel in pH 7.4 PBS buffer for 24 h to allow it to fully swell, then spin-coat or roll it to the target thickness of 150 μm. Finally, dry it under sterile conditions at 60°C for later use. Spin-coating can be performed using a spin coater with a speed set to 1500-2000 rpm and a spin time of 30-60 s. The thickness can be accurately measured using a profilometer or optical profilometer.

[0068] The hydrogel obtained by this process exhibits excellent reversible pH responsiveness, with a volume change rate greater than 200% within the pH range of 4-8. The pKa value of the hydrogel is approximately 5-6. Cytotoxicity is less than 5%, meeting ISO 10993-5 standards. The entire synthesis process requires no organic solvents, making it environmentally friendly, and single-batch yields can reach over 100 g. By precisely controlling the mass ratio of AA to AM (7:3) and the amount of crosslinking agent (0.1-0.5 wt%), the pH response sensitivity and mechanical strength of the hydrogel can be adjusted. AA provides pH-sensitive carboxyl groups, while AM ​​provides mechanical strength and hydrophilicity; the two work synergistically to achieve a balance between high sensitivity and long-term stability.

[0069] Please refer to Figure 7 The pH response characteristics of hydrogels with different formulations were compared. Figure 7 The horizontal axis represents pH value (range 0-12), and the vertical axis represents swelling ratio. The four curves correspond to hydrogel formulations with different monomer ratios or degrees of crosslinking. The specific parameters for the four formulations are as follows: Formulation H1 has an AA:AM mass ratio of 5:5 and MBA content of 0.5 wt%; Formulation H2 has an AA:AM mass ratio of 6:4 and MBA content of 0.3 wt%; Formulation H3 has an AA:AM mass ratio of 7:3 and MBA content of 0.3 wt%; Formulation H4 has an AA:AM mass ratio of 8:2 and MBA content of 0.1 wt%. Figure 7 It can be seen that: (1) All formulations of hydrogels showed significant swelling response in the pH range of 4-8, and the swelling ratio increased with increasing pH, showing an S-shaped curve characteristic; (2) The higher the AA content (H4>H3>H2>H1), the larger the maximum swelling ratio of the hydrogel and the higher the pH response sensitivity. This is because the number of carboxyl groups provided by AA increases, and the degree of deprotonation caused by pH change is greater; (3) The lower the amount of crosslinking agent MBA, the larger the swelling ratio, but the mechanical strength is correspondingly reduced; (4) In the critical pH range of 6-8, the H3 formulation (AA:AM=7:3, MBA=0.3 wt%) showed the best balance between sensitivity and mechanical strength, and the swelling ratio change rate was greater than 200%, so it was selected as the preferred formulation of this application.

[0070] Furthermore, the dielectric material of the pH-sensitive hydrogel can be replaced with Eudragit S100 or poly(N-isopropylacrylamide) variants, which have pKa values ​​in the range of 4-7 and are also suitable for pH data acquisition. The hydrogel thickness is adjusted to 100-150 μm, and the spin coating speed is 2000 rpm for drying. The synthesis process can be adjusted to UV photoinitiation (365 nm, 30 min) to further shorten the reaction time. After replacing the material, only the calibration curve needs to be re-established, and the response range and sensitivity remain consistent.

[0071] The following describes the overall working process of the intelligent dental implant in this embodiment. Please refer to... Figure 1 and Figure 4 When it is necessary to obtain pH data of the microenvironment around the implant, the operator brings the external reader 5 close to the location of the smart dental implant in the oral cavity. The multi-turn transmitting coil of the magnetic field transmitting module 51 in the external reader 5 emits a low-power alternating magnetic field with a frequency of 13.56 MHz. This alternating magnetic field provides excitation energy to the passive LC resonant pH sensor 3 located in the gingival crevicular fluid contact area 21 at the neck of the abutment 2 through inductive coupling. After receiving the alternating magnetic field energy, the helical inductor coil 31 in the passive LC resonant pH sensor 3, together with the variable capacitor 32, is excited, and the LC resonant circuit reflects the signal at its current resonant frequency. Since the pH-sensitive hydrogel dielectric layer has undergone corresponding volume changes under the current gingival crevicular fluid pH environment, changing the capacitance value of the variable capacitor 32, the resonant frequency of the reflected signal carries the information of the current pH value. The receiving coil of the signal receiving module 52 in the external reader 5 receives the reflected signal and measures the resonant frequency value. Subsequently, the data processing module converts the measured resonant frequency value into a pH value based on a pre-established and stored calibration curve of pH value versus resonant frequency, calibrated point-by-point using standard pH buffer solutions (such as pH 4.0, 5.0, 6.0, 7.0, and 8.0). Finally, the pH value is output to a display terminal (such as a mobile app interface, the LCD screen of a dedicated handheld device, or a computer terminal) or storage medium (such as local storage or a cloud server) to generate a microenvironment physicochemical parameter data record. The data can be recorded in time series to generate trend graphs of microenvironment physicochemical parameter changes for professional reference. The entire data acquisition process takes only a few seconds and is easy to operate.

[0072] The implementation principle of this embodiment is as follows: This intelligent dental implant integrates a passive LC resonant pH sensor 3 into the gingival crevicular fluid contact area 21 at the neck of the abutment 2. It utilizes the significant change in dielectric constant caused by volume and water content changes in the pH-sensitive hydrogel dielectric layer under different pH environments to alter the capacitance value of the variable capacitor 32, thereby shifting the resonant frequency of the LC resonant circuit. The magnetic field emitting module 51 in the external reader 5 emits an alternating magnetic field to provide excitation energy for the passive LC resonant pH sensor 3. The passive LC resonant pH sensor 3 reflects the resonant frequency signal, which is received by the signal receiving module 52. The data processing module converts the resonant frequency value into a pH value based on a pre-established correspondence between pH value and resonant frequency, thus achieving passive, non-invasive, and in-situ data acquisition of the pH value of the microenvironment surrounding the implant. This design overcomes the shortcomings of existing pH detection methods and has advantages such as high safety, convenient data acquisition, good compatibility, excellent biocompatibility, high data accuracy, and adjustable hydrogel formulation, providing an effective monitoring solution for the field of oral implant restoration.

[0073] Example 2

[0074] Please refer to Figure 4 and Figure 5 The method for acquiring pH value data of the microenvironment around the intelligent dental implant provided in this application embodiment, using the intelligent dental implant described in Embodiment 1, includes the following steps:

[0075] S1, the external reader 5 is brought close to the oral cavity area where the smart dental implant is installed. The magnetic field transmitting module 51 in the external reader 5 emits an alternating magnetic field to the passive LC resonant pH sensor 3, providing excitation energy to the passive LC resonant pH sensor 3 through inductive coupling. The external reader 5 can be a dedicated handheld device, a modified mobile phone NFC module, or a microcoil integrated into an electric toothbrush. The magnetic field transmitting module 51 adopts a multi-turn transmitting coil structure, emitting a low-power alternating magnetic field at a frequency of 13.56 MHz, with an excitation time in the millisecond range. The dedicated handheld reader can use a 13.56 MHz RFID read / write module, combined with a customized antenna coil, with the transmission power controlled below 10mW, complying with radio management regulations.

[0076] S2, after the passive LC resonant pH sensor 3 is excited, it reflects a signal at its current resonant frequency. The signal receiving module 52 in the external reader 5 receives the reflected signal and measures the resonant frequency value. The signal receiving module 52 adopts a receiving coil structure and is set independently of the transmitting coil of the magnetic field transmitting module 51.

[0077] S3, the data processing module, based on the pre-established correspondence between pH value and resonant frequency ( Figure 5 The figure shows the S-shaped response curve, with the horizontal axis representing the pH value and the vertical axis representing the resonant frequency f0 and R. 2 (>0.98), convert the measured resonant frequency value to pH value. The correspondence can be established in advance as follows: Before the passive LC resonant pH sensor 3 leaves the factory, calibrate it point by point using standard pH buffers (such as pH 4.0, 5.0, 6.0, 7.0, 8.0) to obtain a calibration curve of pH value versus resonant frequency, and store the calibration curve in the memory of the data processing module. In order to prevent response drift that may occur during long-term use of the passive LC resonant pH sensor 3 (caused by hydrogel aging or protein adsorption), zero-point calibration is performed every 6 months using standard buffers.

[0078] S4 outputs the pH value to a display terminal or storage medium to generate microenvironment physicochemical parameter data records. The display terminal can be a mobile app interface, the LCD screen of a dedicated handheld device, or a computer terminal. The storage medium can be local storage or a cloud server. The data can be recorded in time series to generate trend graphs of microenvironment physicochemical parameter changes for professionals' reference.

[0079] The implementation principle of this embodiment is as follows: This method utilizes the magnetic field emission module 51 of the external reader 5 to provide excitation energy to the passive LC resonant pH sensor 3. The passive LC resonant pH sensor 3 reflects the resonant frequency signal, which is received and measured by the signal receiving module 52. The data processing module converts the resonant frequency value into a pH value according to a pre-established correspondence, and finally outputs and records the pH value. The entire process is simple to operate and can be completed in just a few seconds. The passive design ensures zero power consumption and extremely high safety. The acquired pH value data is an objective physicochemical parameter that can serve as the data basis for subsequent analysis.

[0080] Example 3

[0081] Please refer to Figure 1 The intelligent dental implant peri-implant microenvironment pH data acquisition system provided in this application includes the intelligent dental implant described in Embodiment 1, an external reader 5, and a data processing module. The external reader 5 includes a magnetic field transmitting module 51 and a signal receiving module 52. The magnetic field transmitting module 51 includes a transmitting coil (such as...). Figure 1 The multi-turn coil structure shown is used to transmit an alternating magnetic field to the passive LC resonant pH sensor 3 to provide excitation energy through inductive coupling. The signal receiving module 52 includes a receiving coil (such as...). Figure 1 The coil structure shown is used to receive the resonant frequency signal reflected by the passive LC resonant pH sensor 3. The data processing module includes a processor and a memory storing calibration curves. The processor converts the resonant frequency value into a pH value based on a pre-established correspondence between pH value and resonant frequency, and outputs the pH value to a display terminal or storage medium. The data processing module can be integrated into the external reader 5 or be a standalone computing device. The display terminal can communicate with the external reader 5 via Bluetooth or Wi-Fi. Data can be stored on a cloud server for easy retrieval and analysis.

[0082] The following describes the overall working process of the data acquisition system in this embodiment. Please refer to... Figure 1 and Figure 4When the system initiates data acquisition, the transmitting coil of the magnetic field transmitting module 51 in the external reader 5 emits a 13.56 MHz alternating magnetic field. This magnetic field provides excitation energy to the passive LC resonant pH sensor 3, which is installed in the gingival crevicular fluid contact area 21 of the abutment 2, through inductive coupling. After receiving the excitation energy, the spiral inductor coil 31 in the passive LC resonant pH sensor 3, together with the variable capacitor 32, reflects the signal at its current resonant frequency in the LC resonant circuit. The receiving coil of the signal receiving module 52 receives the reflected signal and transmits it to the data processing module. The data processing module converts the resonant frequency value into a pH value according to a pre-stored calibration curve and outputs the pH value to a display terminal or storage medium. All modules of the entire system work together to achieve rapid, accurate, and automated acquisition and recording of the pH value of the microenvironment around the implant.

[0083] The implementation principle of this embodiment is as follows: Through the coordinated work of various modules, the system achieves rapid and accurate acquisition and recording of the pH value of the microenvironment surrounding the intelligent dental implant. The magnetic field emission module 51 provides excitation energy to the passive LC resonant pH sensor 3, the signal receiving module 52 receives the signal reflected by the passive LC resonant pH sensor 3, and the data processing module performs data conversion and output. The system has a high degree of integration, clear division of labor among modules, a compact structure, and a high degree of automation in the data acquisition process, effectively meeting the needs of the dental implant restoration field for monitoring the pH value of the microenvironment surrounding the implant.

[0084] The specific embodiments described above do not constitute a limitation on the scope of protection of this application. Any other corresponding changes and modifications made based on the technical concept of this application should be included within the scope of protection of this application.

Claims

1. A smart dental implant, characterized in that, include: Implant body (1); Abutment (2), which is connected to the implant body (1); A crown (4) is mounted on top of the abutment (2); A passive LC resonant pH sensor (3) is disposed at the neck of the base (2). The passive LC resonant pH sensor (3) includes a spiral inductor (31), a variable capacitor (32), and a flexible substrate (33). The spiral inductor (31) is used to receive external alternating magnetic field energy to excite the LC resonant circuit and reflect the resonant frequency signal of the LC resonant circuit to the outside through inductive coupling. The variable capacitor (32) includes two parallel plate metal electrodes and a pH-sensitive hydrogel dielectric layer sandwiched between the two parallel plate metal electrodes. The pH-sensitive hydrogel dielectric layer undergoes volume changes under different pH environments. The change in the water content of the hydrogel leads to a significant change in the dielectric constant, thereby changing the capacitance value of the variable capacitor (32). The flexible substrate (33) is a flexible thin film used to support the spiral inductor (31) and the variable capacitor (32). The spiral inductor (31) and the variable capacitor (32) are electrically connected to form an LC resonant circuit. When the pH value of the liquid in contact with the pH-sensitive hydrogel dielectric layer changes, the capacitance value of the variable capacitor (32) changes accordingly, causing the resonant frequency of the LC resonant circuit to shift.

2. The intelligent dental implant according to claim 1, characterized in that, The spiral inductor (31) is made of Cu or Ag conductive material, with 5-10 turns, a diameter of 2-4 mm, and a line width of 0.10-0.20 mm.

3. The intelligent dental implant according to claim 1, characterized in that, The pH-sensitive hydrogel dielectric layer is made of polyacrylic acid-co-acrylamide copolymer hydrogel, wherein the mass ratio of acrylic acid to acrylamide is 7:3, the crosslinking agent is N,N'-methylenebisacrylamide, and the amount of the crosslinking agent is 0.1-0.5 wt% of the total monomer mass. The thickness of the pH-sensitive hydrogel dielectric layer is 50-200 μm. The polyacrylic acid-co-acrylamide copolymer hydrogel is synthesized by free radical solution polymerization, where the acrylic acid monomer provides the pH-sensitive carboxyl groups and the acrylamide monomer provides the mechanical strength.

4. The intelligent dental implant according to claim 1, characterized in that, The flexible substrate (33) is a polyimide film with a thickness of 25-50 μm; the outer surface of the passive LC resonant pH sensor (3) is provided with a Parylene-C waterproof coating (34) that avoids the liquid contact surface of the pH-sensitive hydrogel dielectric layer, and the thickness of the Parylene-C waterproof coating (34) is 5-10 μm.

5. The intelligent dental implant according to claim 1, characterized in that, The passive LC resonant pH sensor (3) is fixed to the neck of the base (2) by one of the following methods: Wrapping fixation: Cut the passive LC resonant pH sensor (3) into strips and wrap them around the neck of the abutment (2) 1-2 times, with the pH-sensitive hydrogel dielectric layer facing away from the abutment (2); or Adhesive fixing: The passive LC resonant pH sensor (3) is made into an arc-shaped patch and adhered to the neck of the base (2); In both the winding fixation and the adhesive fixation, the passive LC resonant pH sensor (3) is bonded to the neck of the abutment (2) through an adhesive fixing layer (35), and the material of the adhesive fixing layer (35) is a UV-curable dental adhesive.

6. The intelligent dental implant according to claim 1, characterized in that, The base (2) is a 3D printed integral base. The neck of the base (2) is provided with a reserved micro groove. The passive LC resonant pH sensor (3) is embedded in the reserved micro groove and fixed by filling resin. The depth of the reserved micro groove is 0.2-0.5 mm.

7. The intelligent dental implant according to claim 1, characterized in that, The surface roughness Ra of the passive LC resonant pH sensor (3) in contact with the external liquid is 0.2-0.5 μm; the surface of the passive LC resonant pH sensor (3) facing the external soft tissue is activated by O2 plasma to introduce hydrophilic groups, and the hydrophilic groups are fixed by chemical grafting to prevent the hydrophilicity from decaying due to aging effect, so that the surface contact angle of the flexible substrate (33) is reduced to below 30°.

8. A method for acquiring pH data of the microenvironment surrounding a smart dental implant, characterized in that, Using the intelligent dental implant according to any one of claims 1-7 includes the following steps: S1. Bring the external reader (5) close to the oral cavity area where the smart dental implant is installed. The magnetic field emission module (51) in the external reader (5) emits an alternating magnetic field to the passive LC resonant pH sensor (3) and provides excitation energy to the passive LC resonant pH sensor (3) through inductive coupling. S2, the passive LC resonant pH sensor (3) reflects a signal at its current resonant frequency, and the signal receiving module (52) in the external reader (5) receives the reflected signal and measures the resonant frequency value; S3. The data processing module converts the measured resonant frequency value into a pH value according to the pre-established correspondence between pH value and resonant frequency. The correspondence is established by calibrating the passive LC resonant pH sensor (3) point by point using a standard pH buffer solution before it leaves the factory and is stored in the memory of the data processing module. S4. Output the pH value to a display terminal or storage medium to generate microenvironment physicochemical parameter data records.

9. A smart system for acquiring pH data of the microenvironment around dental implants, characterized in that, include: The intelligent dental implant according to any one of claims 1-7; as well as An external reader (5) includes a magnetic field emitting module (51) and a signal receiving module (52). The magnetic field emitting module (51) includes a transmitting coil for emitting an alternating magnetic field to the passive LC resonant pH sensor (3) to provide excitation energy through inductive coupling. The signal receiving module (52) includes a receiving coil for receiving the resonant frequency signal reflected by the passive LC resonant pH sensor (3). as well as The data processing module includes a processor and a memory storing calibration curves. The processor is used to convert the received resonant frequency signal into a pH value according to a pre-established correspondence between pH value and resonant frequency, and output the pH value to a display terminal or storage medium.

10. A method for synthesizing a pH-sensitive hydrogel dielectric layer, used for synthesizing the pH-sensitive hydrogel dielectric layer of the variable capacitance (32) in the intelligent dental implant of claim 1, characterized in that, Includes the following steps: Step 1, Monomer preparation: Dissolve acrylic acid (AA) and acrylamide (AM) in deionized water at a mass ratio of 7:3 to prepare a solution with a total monomer concentration of 10-20 wt%. Add crosslinking agent N,N'-methylenebisacrylamide (MBA), with the amount of MBA being 0.1-0.5 wt% of the total monomer mass. Stir magnetically until completely dissolved. Step 2, Initiator addition: After purging N2 into the solution obtained in Step 1 to remove oxygen for 20-40 min, add the ammonium persulfate (APS) / sodium bisulfite (SBS) redox initiator system, each accounting for 0.3-0.8 wt% of the total monomer mass, and continue stirring until homogeneous; Step 3, polymerization reaction: The mixture obtained in step 2 is injected into a thickness-controlled mold and reacted in a water bath at 60-70°C for 4-6 hours to complete the polymerization; or the polymerization is initiated by ultraviolet light with a wavelength of 365 nm and a light intensity of 8-12 mW / cm² for 30-60 minutes to obtain a hydrogel film. Step 4, purification and drying: Soak the hydrogel obtained in step 3 in deionized water for 60-80 h, changing the water every 10-14 h to remove unreacted monomers and initiator residues, and then vacuum dry at 35-45°C to constant weight to obtain a dry gel film; Step 5, Activation and Thickness Control: Soak the dry gel film obtained in Step 4 in PBS buffer at pH 7.4 for 20–28 h to allow it to fully swell, then spin-coat or calender it to the target thickness of 50–200 μm, and dry it under sterile conditions for later use.

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