Lc sensor for monitoring physiological signals of a human body and intelligent invisible mouthpiece

Abstract

This invention discloses an LC sensor for monitoring human physiological signals and a smart invisible braces. The LC sensor provided by this invention comprises, from bottom to top, an inductor coil layer, a capacitor layer, a dielectric layer, another capacitor layer, and another inductor coil layer. Specifically: the inductor coil layer is composed of a silver paste inductor coil encapsulated in a heat-laminated film; the capacitor layer is made of one or more of indium tin oxide (ITO), aluminum-doped zinc oxide (ZAO), graphene, and a conductive polymer composite PEDOT:PSS; and the dielectric layer is made of PDMS. This invention also provides a smart invisible braces containing the aforementioned LC sensor, which enables non-invasive, dynamic, and real-time precise monitoring of orthodontic forces in a real oral environment, thereby providing reliable data support for biomechanical optimization and personalized treatment of invisible braces.

Description

Technical Field

[0001] This invention belongs to the field of flexible sensing and medical device technology, specifically relating to an LC sensor for monitoring human physiological signals and a smart invisible braces. Background Technology

[0002] With advancements in materials science, orthodontic appliances have evolved from fixed braces and removable braces to clear aligners (also known as invisible aligners). This technology utilizes computer-aided 3D modeling to develop treatment plans and then mechanically manufactures a series of orthodontic devices to achieve corrective goals through periodic periodontal displacement. Compared to traditional fixed braces, which are not removable, inconvenient to clean, and aesthetically unappealing, clear aligners significantly improve the patient experience due to their removable, clean, and transparent design, making them the preferred option for modern orthodontics.

[0003] Invisible aligners are made from transparent, high-hardness thermoplastic polymer materials through heating and molding. Their orthodontic efficiency directly depends on the precise control of the orthodontic force. Insufficient orthodontic force may lead to inefficient tooth movement, while excessive orthodontic force may cause damage to periodontal tissues. Therefore, real-time and accurate measurement of orthodontic force is a key prerequisite for optimizing treatment results and ensuring treatment safety.

[0004] However, existing invisible aligners mainly have the following problems:

[0005] 1. Material processing: Currently, the elastic modulus of the molded sheet material of invisible aligners is obtained through laboratory uniaxial tensile tests. However, after the sheet material is heated and softened, laser-cut edges, and sterilized, its mechanical properties will change, which makes the laboratory data unable to accurately reflect the actual orthodontic force generated by the aligners.

[0006] 2. In terms of calculation methods: Finite element analysis is the representative method. It simulates mechanical response through modeling. Although it is highly repeatable and has no ethical issues, the simplification of modeling due to the complexity of periodontal tissue morphology and mechanical properties leads to deviations between the results and the actual situation.

[0007] 3. Existing experimental measurement technologies: (1) Strain gauge technology: It is attached to the teeth or orthodontic appliance and calculates the force value through the change of resistance. It is simple to operate but is greatly affected by the attachment position and oral environment, and has poor adaptability; (2) Optical measurement: It uses the principle of light interference / diffraction to measure deformation. It has high precision but the equipment is complex, costly, and has strict environmental requirements; (3) Pressure-sensitive membrane: It reflects the pressure distribution through color change. It is intuitive but can only obtain instantaneous data. The quantitative analysis error is large and it cannot be continuously monitored; (4) Wireless sensing technology: It integrates sensors and transmits data with the help of Bluetooth / NFC. It has good real-time performance but faces challenges in sensor miniaturization, power consumption and integration process; In addition, CN106491220A discloses a device composed of orthodontic appliance and sensor. The device can sense the pressure value between the appliance and the teeth, but does not give the specific sensor structure and manufacturing process. The existing commercially available sensors are not compatible with invisible braces and it is difficult to achieve the above functions.

[0008] As mentioned above, the limitations of existing orthodontic force measurement technology severely restrict the precise optimization of treatment plans: the lack of direct, dynamic, and imperceptible intraoral measurement means that doctors cannot adjust orthodontic plans based on real-time force values, and patients cannot obtain a personalized treatment experience.

[0009] Therefore, there is an urgent need to develop "smart braces" that integrate micro-sensors, wireless transmission technology, and are invisible in color. By embedding micro-sensors that are highly matched to the teeth in the braces, real, dynamic, and imperceptible monitoring of orthodontic forces can be achieved. This will not only improve treatment efficiency and safety, but also promote the development of orthodontic treatment towards intelligence and personalization, filling the gaps in existing technologies.

[0010] In view of this, the present invention is hereby proposed. Summary of the Invention

[0011] The purpose of this invention is to provide an LC sensor that can be used to monitor human physiological signals and a smart brace made from it. This LC sensor is characterized by its invisibility, high precision, high stability, and short response time. It can be integrated with invisible devices used to monitor human physiological signals (such as invisible braces) for extended periods, enabling real, dynamic, and imperceptible monitoring of orthodontic force. Furthermore, the manufacturing process is simple, low-cost, and allows for customized sizes and shapes.

[0012] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0013] In a first aspect, the present invention provides an LC sensor for monitoring human physiological signals, having a five-layer sandwich symmetrical structure, which, from bottom to top, consists of an inductor coil layer, a capacitor layer, a dielectric layer, a capacitor layer, and an inductor coil layer; wherein:

[0014] The inductor coil layer is composed of a silver paste inductor coil that is thermally laminated and laser-printed.

[0015] The heat-laminating film is made of a transparent material; preferably, the heat-laminating film is made of one or more of BOPP film, PET and medical tape.

[0016] The capacitor layer is made of one or more of the following materials: indium tin oxide (ITO), aluminum-doped zinc oxide (ZAO), graphene, and conductive polymer composite PEDOT:PSS.

[0017] The dielectric layer is made of an elastic material; preferably, the dielectric layer is made of PDMS.

[0018] This invention uses silver paste to make inductor coils and selects transparent thermal lamination films such as BOPP for encapsulation. This not only reduces the raw material cost of the sensor and simplifies the manufacturing process, but also ensures that the encapsulation material has good biocompatibility with the tooth. The product has high transparency after encapsulation and curing, which meets the appearance requirements of invisible braces. The material has high hardness after encapsulation, which can effectively transmit the force applied by the braces and improve the monitoring accuracy. In addition, the encapsulation material has good plasticity in the uncured state and can closely conform to the tooth surface morphology.

[0019] This invention also selects materials for the dielectric and capacitor layers to ensure that they meet the functional requirements of each layer and have high light transmittance, thus satisfying the needs of invisible braces.

[0020] Furthermore, the thickness of the inductor coil layer is 35-45 μm.

[0021] Furthermore, the diameter of a single wire in the silver paste inductor coil ranges from 0.1mm to 0.4mm; the wire spacing can be adjusted according to actual application requirements. If applied to braces, the wire spacing ranges from 0.1mm to 0.3mm.

[0022] Furthermore, the thickness of the silver paste inductor coil is 9-11 μm, and the thickness of the thermally laminated film is 19-21 μm.

[0023] Furthermore, the thickness of the capacitor layer is 45-55 μm; the side length of the capacitor layer is 1-3 mm.

[0024] Furthermore, the thickness of the dielectric layer is 90-110 μm.

[0025] Furthermore, the LC sensor is a square device with a side length of 5-6mm.

[0026] Secondly, the present invention provides a method for preparing the above-mentioned LC sensor, comprising the following steps:

[0027] S1. Prepare the capacitor layer;

[0028] S2. Prepare the silver paste inductor coil layer;

[0029] S3. Prepare the dielectric layer;

[0030] S4. Assemble the capacitor layer, silver paste inductor coil layer and dielectric layer to obtain the LC sensor.

[0031] In step S2, the silver paste inductor coil layer is prepared according to the following operation: silver paste is coated onto the surface of the heat-laminated film using a coater, the desired pattern is formed by laser irradiation, and the uncured silver paste is removed to obtain the inductor coil layer bonded to the heat-laminated film; the parameters of the laser irradiation include: wavelength 320-400nm, marking distance defocus ± (0-2cm), marking frequency 50-80kHz, and marking repeated 1-100 times.

[0032] As a specific embodiment of the present invention, the parameters of the laser irradiation are: UV marking machine: wavelength 355nm, laser mode TEM. 00 Laser peak power >10KW, laser beam quality M2 <1.5, marking range 110X110mm, marking depth ≤3mm, marking line speed 3mm / s, repeatability marking accuracy ≤10μrad, power consumption ≤1KW, power requirement 220VAC / 50Hz.

[0033] In step S3, the dielectric layer is prepared by the following operation: the slurry is spin-coated onto sandpaper, baked and cured, and then cut to obtain the dielectric layer.

[0034] In one specific embodiment of the present invention, the sandpaper has a mesh size of 180 and is baked under the following conditions: temperature 60-100℃ and time 35-60min.

[0035] The ITO capacitor layer can be purchased commercially or prepared using conventional manufacturing processes in the art.

[0036] Thirdly, the present invention also provides the application of the above-mentioned LC sensor in a concealed device for monitoring human physiological signals.

[0037] The invisible device includes flexible wearable monitoring devices or implantable medical monitoring devices.

[0038] The flexible wearable monitoring device includes contact lenses.

[0039] The implantable medical monitoring device includes invisible braces.

[0040] Fourthly, the present invention provides a smart invisible brace, including a slot; the slot has the aforementioned LC sensor built into it.

[0041] Fifthly, the present invention also provides a method for preparing the above-mentioned smart invisible braces, comprising the following steps:

[0042] S1. Create a 3D model of the patient's teeth, design slots at the required monitoring tooth positions, print the model to obtain a tooth model 1 with slots; at the same time, print another tooth model 2 without slots.

[0043] S2. Make a dental crown with slots based on dental model 1, install sensors in the slots and fix them in place, and then put the dental crown into dental model 2 and press it flat.

[0044] S3. Remove the braces, let them set again, and you will have smart invisible braces.

[0045] In step S1, the thickness of the slot is 1~2mm. The length and width dimensions of the slot match the length and width dimensions of the sensor.

[0046] In step S2, the fixing can be performed as follows: Apply 3M Transbond dental resin adhesive to the slot and sensor surface with a small cotton swab, let it stand for 10 seconds, gently blow it evenly with an air gun to ensure that the adhesive is thin and uniform, and then cure it with blue light for 10 seconds.

[0047] In step S2, in one embodiment of the present invention, the dental crown is removed from the dental model 2, and excess adhesive outside the slot is removed using an oral examination probe.

[0048] In step S3, the curing is performed using blue light for 18-22 seconds.

[0049] In this invention, the smart invisible braces can also be prepared in the following ways:

[0050] (1) The patient's teeth are scanned with an oral scanner to obtain a 3D printed model, and the dental model is obtained by 3D printing.

[0051] (2) Attach the sensor to the adhesive side of the single-sided adhesive (the adhesive side area is larger than the sensor area), apply semi-cured PDMS to the back of the single-sided adhesive, and fix it to the required monitoring tooth position on the dental model.

[0052] (3) After heating the dental membrane, press it onto the dental model with the sensor, draw a vacuum, and remove the dental cover along the gingival margin after shaping to obtain the dental cover with the sensor. Then cure it to obtain the final product.

[0053] During this process, the sensor attached to the dental model adheres tightly to the dental membrane through the softening of the membrane and the adhesiveness of the bio-adhesive tape, thus achieving the purpose of fixing the sensor to the dental brace.

[0054] The curing process involves placing the PDMS at room temperature for more than 12 hours to allow it to fully cure.

[0055] Compared with the prior art, the beneficial effects achieved by the present invention are:

[0056] 1. This invention uses commonly used dental materials with clinically proven biocompatibility to completely encapsulate the sensor, ensuring good biocompatibility; all encapsulation materials are transparent or tooth-colored, so that the sensor and braces are integrated after wearing; the encapsulation adhesive is hard after curing, which can effectively transmit the force applied by the braces to the sensor; at the same time, the adhesive has good plasticity in the uncured state and can closely fit the surface morphology of the teeth.

[0057] 2. The LC sensor provided by this invention has the characteristics of being invisible and transparent, having a short response time, high stability, and high precision (sensitive to minute forces, with a minimum force measurement value of 0.02N). It can be combined with devices such as invisible braces and contact lenses for a long time to collect human physiological and mechanical signals. At the same time, the LC sensor has a simple manufacturing process, low cost, and can be customized in various sizes and shapes.

[0058] 3. The LC sensor design provided by this invention overcomes the shortcomings of existing piezoresistive sensors, pressure films, and 3D force sensors, such as relying on external models, strong presence, complex operation, and poor aesthetics (unusual color / exposed wires). The smart braces made from it can achieve non-invasive, dynamic, and real-time accurate monitoring of orthodontic force in a real oral environment, thereby providing reliable data support for biomechanical optimization and personalized treatment of invisible orthodontics.

[0059] 4. The smart braces provided by this invention achieve contactless signal acquisition, have no internal power supply, and have no risk of electrical insulation problems such as leakage. They also have high light transmittance, good stability, and are suitable for long-term in vivo measurement. Attached Figure Description

[0060] Figure 1 This is a perspective view of the structure of the LC sensor provided by the present invention.

[0061] Figure 2(a) is a process flow diagram of the inductor part fabricated using laser sintering silver paste technology.

[0062] Figure 2(b) is a process flow diagram of the sensor fabrication using laser sintering silver paste technology.

[0063] Figure 3 The image shows the appearance of the LC sensor provided by the present invention; the left side is a copper sensor, and the right side is a silver paste stealth sensor prepared by the present invention.

[0064] Figure 4(a) shows the response time of the LC sensor provided by the present invention.

[0065] Figure 4(b) shows the results of repeated continuous pressure test of the LC sensor provided by the present invention.

[0066] Figure 5(a) shows the vertical distance of the LC sensor provided by the present invention.

[0067] Figure 5(b) shows the horizontal displacement of the LC sensor provided by the present invention.

[0068] Figure 6 SEM scans of the finished products obtained by different silver paste sintering methods.

[0069] Figure 7(a) shows the SEM scan of PDMS dielectric layers with different microstructures.

[0070] Figure 7(b) is a comparison of the force measurement range of PDMS dielectric layers with different microstructures.

[0071] Figure 8(a) is a schematic diagram of the principle of measuring and monitoring tooth movement by force in invisible braces provided by the present invention.

[0072] Figure 8(b) is a block diagram illustrating the working principle of the invisible braces force measurement and monitoring of tooth movement provided by the present invention.

[0073] Figure 9(a) shows a photograph of the invisible braces provided by the present invention in use; the left side is the smart braces containing sensors of the present invention, and the right side is a regular orthodontic appliance.

[0074] Figure 9(b) is a grayscale distribution diagram of the invisible braces provided by the present invention.

[0075] Figure 10 The waterproof performance test results of the invisible braces provided by this invention.

[0076] Figure 11 The results of the process stability test for the invisible braces provided by this invention.

[0077] Figure 12 The mechanical performance test results of the invisible braces provided by the present invention were continuously monitored on an in vitro model for 14 days; where the left side represents the frequency and the right side represents the force value. Detailed Implementation

[0078] The present invention will be further described below with reference to specific embodiments, but the present invention is not limited to the following embodiments.

[0079] Unless otherwise specified, the experimental methods used in the following examples are conventional methods.

[0080] Unless otherwise specified, all reagents, materials, instruments, etc. used in the following examples are commercially available.

[0081] The silver paste used in the following examples is a commercially available product, brand and model DJ002, and its formula is as follows: 40%-80% conductive filler, 10%-50% compound resin, 5%-10% diluent, and 1%-5% additives.

[0082] Example 1: Fabrication of an LC sensor

[0083] The LC sensor provided in this embodiment is a square device with a side length of 5-6 mm. Its structure is a five-layer sandwich symmetrical structure, as shown below. Figure 1 As shown, from bottom to top, they are: thermally laminated silver paste inductor coil layer, ITO capacitor layer, PDMS dielectric layer, ITO capacitor layer, and thermally laminated silver paste inductor coil layer.

[0084] in:

[0085] Inductor coil layer: Its overall thickness is 40μm, the diameter of a single wire of the silver paste coil is 0.1mm, the wire spacing of a single wire is 0.3mm; the thickness of the coil is 10μm, and the thickness of the heat-mounted film is 20μm.

[0086] ITO capacitor layer: It is a square with a side length of 1-3mm and a thickness of 50μm. The ITO is soldered to the interface of the silver paste coil.

[0087] PDMS dielectric layer: 100μm thick, used to sense changes in pressure.

[0088] This embodiment also provides a method for fabricating the above-mentioned LC sensor, specifically including the following:

[0089] (1) Using conventional methods, ITO was processed by laser to obtain a square capacitor layer with dimensions of 3mm*3mm.

[0090] (2) As shown in Figure 2(a) and Figure 2(b), the silver paste is evenly coated onto the heat-mounted film (BOPP film) using a coater. The BOPP film is then transferred to a UV marking machine. The UV marking machine is set with specific parameters and the silver paste is cured into the designed pattern under defocus conditions. Finally, the uncured silver paste is cleaned with alcohol to obtain an inductor coil layer that is bonded to the heat-mounted film. The inductor coil layer is square and has a size of 6mm*6mm.

[0091] The parameters for laser irradiation are as follows: UV marking machine: wavelength 355nm, laser mode (TEM). 00 Laser peak power >10KW, laser beam quality M2 <1.5, marking range 110X110mm, marking depth ≤3mm, marking line speed 3mm / s, repeat marking accuracy ≤10μrad, power consumption ≤1KW, power requirement 220VAC / 50Hz, marking distance defocus ±(0-2cm), marking frequency 50-80kHz, repeat marking 1-100 times.

[0092] (3) Spin coat PDMS (liquid state) onto 180 grit sandpaper, put the sandpaper into an oven and bake at 80°C for 40 minutes to cure PDMS and give it the shape of the sandpaper. Cut it with a laser to obtain PDMS in a shape suitable for inserting into the sensor and obtain the dielectric layer.

[0093] (4) ITO is attached to the BOPP film with a soldering iron and connected to the solder head of the silver paste coil. Finally, the PDMS dielectric layer is installed and the BOPP film is heat-sealed with a soldering iron to obtain the LC sensor.

[0094] Sensor performance verification:

[0095] 1. Transparency

[0096] (1) Appearance: such as Figure 3 As shown, compared with traditional LC sensors, the LC sensor obtained by this invention is more transparent and more suitable for long-term integration with invisible devices such as invisible braces and contact lenses to collect human physiological and mechanical signals.

[0097] (2) Transmittance test:

[0098] The transmittance test method is as follows: Under fixed shooting conditions such as lighting position, take pictures of both the copper sensor and the invisible sensor, and process the pictures. The area with the sensor is regarded as the detection area, and the area without the sensor is regarded as the background area. The transmittance is the average gray value of the detection area divided by the average gray value of the background area.

[0099] The test results are shown in the table below. The light transmittance of the invisible sensor prepared by this invention is significantly higher than that of existing copper sensors, reaching the level of ordinary glass transmittance (80-90%).

[0100] Table 1

[0101] copper sensor This invention is a stealth sensor <![CDATA[Average gray scale I0 of the background area]]> 243.66 231.91 <![CDATA[Average gray level I1 of the detection area]]> 177.09 202.08 <![CDATA[Transmittance = I1 / I0]]> 72.68% 87.14%

[0102] 2. Response speed: As shown in Figures 4(a) and 4(b), the response time of the LC sensor obtained by this invention is 6s, and its performance remains stable under repeated pressure conditions.

[0103] 3. Optimal transmission distance: As shown in Figures 5(a) and 5(b), the optimal transmission distance of the LC sensor obtained by this invention is 1.2mm, which is sufficient to monitor human physiological and mechanical data when used with invisible braces or contact lenses.

[0104] 4. Structural stability: such as Figure 6As shown, compared with the common silver paste sintering method (heating and natural drying), the silver paste obtained by the laser sintering technology used in this invention is in sheet form, with better density, tighter connection, and more complete structure.

[0105] 5. Force Measurement Range: As shown in Figures 7(a) and 7(b), the tangent with a slope of -0.1 is the limit of the sensor's detection force (i.e., when k>-0.1, the sensor sensitivity>1MHz / N, which is considered accurate in force measurement). It can be seen that the force measurement range of the sensor with a flat dielectric layer is 0-1N, the measurement range of the dielectric layer made of 180-grit sandpaper is 0-2.4N, and the force measurement range of the sensor made of a dielectric layer made of 320-grit sandpaper is 0-1.4N. Therefore, 180-grit sandpaper is chosen to make the dielectric layer to expand the measurement range.

[0106] 6. Comparison of different manufacturing processes: Screen printing and laser sintering processes, which are currently the mainstream manufacturing processes for inductor coils, were used for comparative testing.

[0107] The results showed that the yield rate of sensors prepared by screen printing was only 20%, with a high failure rate. The screen holes were easily blocked during the manufacturing process, resulting in weak signals and a maximum attenuation of only 0.3dB. In contrast, the yield rate of sensors prepared by laser sintering reached 58%, which is a higher yield rate. The signals of the sensors prepared by laser sintering were stronger, with a maximum attenuation of 1-3dB.

[0108] Example 2: Preparation of Smart Invisible Braces

[0109] This embodiment provides a method for preparing smart invisible braces, which specifically includes the following steps:

[0110] (1) A 3D model of the patient's mouth was created using an oral scanner to design a step-by-step orthodontic treatment plan; then, a slot was designed on the labial side of the maxillary lateral incisor to accommodate the sensor prepared in Example 1. The slot was 5mm long, 6mm wide, and 2mm thick.

[0111] (2) Print the designed dental model 1 and make the orthodontic appliance to obtain a transparent brace with slots;

[0112] (3) Place the sensor in the slot;

[0113] (4) Apply dental resin adhesive to the slot and sensor surface with a small cotton swab for 10 seconds, then gently blow it evenly with an air gun to ensure that the adhesive is thin and uniform.

[0114] (5) Curing with blue light for 10 seconds;

[0115] (6) Fill the slot with 3M Transbond light-cured orthodontic adhesive until the adhesive slightly overflows;

[0116] (7) Print a dental model 2 with the same orthodontic design but without slots;

[0117] (8) Place the braces into the dental model 2 and gently press the grooves until excess adhesive overflows, ensuring that the orthodontic bonding resin adheres to the tooth surface;

[0118] (9) Remove the dental brace from the dental model 2 and use an oral examination probe to remove any excess adhesive outside the slot;

[0119] (10) Curing with blue light for 20 seconds, such as light curing.

[0120] Effect Verification 2:

[0121] 1. Principle of force measurement and tooth movement monitoring for invisible braces

[0122] As shown in Figures 8(a) and 8(b), the sensor is located in the slot of the braces. The elastic retraction force of the braces will cause the teeth to move. The sensor in the braces slot can sense the change of the elastic retraction force. When the sensor is subjected to force, its resonant frequency will change. Therefore, by measuring the resonant frequency, the elastic retraction force of the braces can be inferred, thereby guiding the doctor to design the orthodontic plan for the patient and deepening the understanding of the orthodontic situation for both the patient and the doctor.

[0123] When a patient wears braces, the force values ​​measured by sensors reflect the state of tooth movement. By monitoring the orthodontic force applied to the teeth by the invisible aligners in real time, the alveolar bone remodeling is detected, thereby reflecting the tooth movement and informing the patient and doctor in a timely manner whether the aligners need to be replaced and whether the aligners are suitable for the patient.

[0124] 2. Comparison with existing orthodontic appliances

[0125] Compared with ion braces, the invisible braces provided by this invention adopt a passive wireless signal transmission method, which can collect signals without contact and is more suitable for long-term in-vivo measurement.

[0126] Compared to integrated orthodontic appliances, the invisible braces provided by this invention use passive LC sensors, which have no internal power supply and no risk of electrical insulation problems such as leakage. In addition, the invisible braces of this invention do not significantly alter the original shape of the appliance, and the normal function of the appliance can be protected to the greatest extent, making them more suitable for in-vivo measurement.

[0127] Compared with conventional dental appliances, as shown in Figures 9(a) and 9(b), by comparing the average gray values of the tooth regions in the two pictures (average gray value difference = |average gray value of the intelligent dental appliance - average gray value of the ordinary dental appliance| / average gray value of the ordinary dental appliance = 0.03 < p (statistical difference p = 0.05), that is, there is no statistical difference between the two dental appliances), the visual gap between the intelligent dental appliance and the ordinary dental appliance at the social distance is reflected, without affecting the patient's daily life and social interactions.

[0128] 3. Feasibility Proof of the Intelligent Dental Appliance

[0129] Experimental Scheme: Test the aesthetics, waterproof performance, mechanical properties, and manufacturing process stability of the intelligent dental appliance.

[0130] Aesthetics: As shown in Figure 9.

[0131] Waterproof Performance: As Figure 10 shown, the sensor was immersed in a lemon yellow liquid for a total of 48 hours. By measuring the average gray value of the intelligent dental appliance pictures at different times, it was judged whether the sensor part of the intelligent dental appliance was stained by lemon yellow. From the data, it can be seen that the light transmittance of the intelligent dental appliance has always remained above 85%, so it was not stained.

[0132] Manufacturing Process Stability: As Figure 11 shown, four intelligent dental appliances with the same theoretical values prepared by the preparation method described in the present invention. By measuring the initial frequency of the sensor in the intelligent dental appliance, it can be seen that the manufacturing method described in the present invention does not damage the performance of the sensor, preliminarily proving the feasibility of the intelligent dental appliance for measuring orthodontic force.

[0133] Mechanical Property Stability: As Figure 12 shown, the intelligent dental appliance (sensors are installed at tooth positions 11, 21, 22, 12, and 13) was worn on the dental arch model of the corresponding patient and continuously monitored for 14 days. The results showed that both the frequency and the corresponding stress values remained stable, indicating that the intelligent dental appliance provided by the present invention has good mechanical stability.

[0134] Although the present invention has been described in detail with general descriptions and specific implementation examples above, based on the present invention, some modifications or improvements can be made, which are obvious to those skilled in the art. Therefore, these modifications or improvements made without departing from the spirit of the present invention all fall within the scope of protection required by the present invention.

Claims

1. An LC sensor for dental applications, comprising, from bottom to top, an inductor coil layer, a capacitor layer, a dielectric layer, another capacitor layer, and an inductor coil layer; wherein: The inductor coil layer is composed of a silver paste inductor coil that is thermally laminated and laser-printed. The heat-laminated film is made of a transparent material; The capacitor layer is made of one or more of the following materials: indium tin oxide (ITO), aluminum-doped zinc oxide (ZAO), graphene, and conductive polymer composite PEDOT:PSS. The dielectric layer is made of an elastic material.

2. The LC sensor according to claim 1, characterized in that, The heat-laminated film is made of one or more of BOPP film, PET, and medical tape. The dielectric layer is made of PDMS.

3. The LC sensor according to claim 1 or 2, characterized in that, The thickness of the inductor coil layer is 35-45 μm; The diameter of a single wire in the silver paste inductor is between 0.1 mm and 0.4 mm. The thickness of the silver paste inductor coil is 9-11 μm, and the thickness of the thermally laminated film is 19-21 μm; The thickness of the capacitor layer is 45-55 μm; The side length of the capacitor layer is 1-3mm; The thickness of the dielectric layer is 90-110 μm.

4. A method for manufacturing the LC sensor according to any one of claims 1-3, comprising the following steps: S1. Prepare the capacitor layer; S2. Prepare the silver paste inductor coil layer; S3. Prepare the dielectric layer; S4. Assemble the capacitor layer, silver paste inductor coil layer and dielectric layer to obtain the LC sensor.

5. The preparation method according to claim 4, characterized in that, In step S2, the silver paste inductor coil layer is prepared according to the following operation: silver paste is coated onto the surface of the heat-mounted film using a coater, the desired pattern is formed by laser irradiation, the uncured silver paste is removed, and an inductor coil layer bonded to the heat-mounted film is obtained. The parameters of the laser irradiation include: wavelength 320-400nm, marking distance defocus ± (0-2cm), marking frequency 50-80kHz, and repeating marking 1-100 times; In step S3, the dielectric layer is prepared by the following operation: the slurry is spin-coated onto sandpaper, baked and cured, and then cut to obtain the dielectric layer.

6. The application of the LC sensor according to any one of claims 1-3 in a stealth device for monitoring human physiological signals.

7. A flexible wearable monitoring device, comprising the LC sensor according to any one of claims 1-3.

8. An implantable medical monitoring device, comprising the LC sensor according to any one of claims 1-3.

9. A smart invisible brace, comprising a slot; wherein the slot houses an LC sensor as described in any one of claims 1-3.

10. The method for preparing the smart invisible braces according to claim 9, characterized in that, Prepared in the following two ways: Method 1 includes the following steps: S1. Create a 3D model of the patient's teeth, design slots at the required monitoring tooth positions, print the model to obtain a tooth model 1 with slots; at the same time, print another tooth model 2 without slots. S2. Make a dental crown with slots based on dental model 1, install sensors in the slots and fix them in place, and then put the dental crown into dental model 2 and press it flat. S3. Remove the braces, re-curing them to achieve smart invisible braces; Method 2 includes the following steps: (1) The patient's teeth are scanned with an oral scanner to obtain a 3D printed model, and the dental model is obtained by 3D printing. (2) Attach the sensor to the adhesive side of the single-sided adhesive, with the adhesive side area being larger than the sensor area. Apply semi-cured PDMS to the back of the single-sided adhesive and fix it to the required monitoring tooth position on the dental model. (3) After heating the dental membrane, press it onto the dental model with the sensor, draw a vacuum, and remove the dental cover along the gingival margin after shaping to obtain the dental cover with the sensor. Then cure it to obtain the final product.

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