Detection method and preparation method of tactile optical fiber sensor based on electro-optical fusion

Abstract

The invention relates to the technical field of bionic touch, in particular to a detection method and a preparation method of a touch optical fiber sensor based on electro-optical fusion. According to the tactile fiber sensor, a joint sensor comprising an optical channel and an electric channel is constructed, a photoelectric joint model is established, and decoupling of mechanical deformation and temperature interference is realized by using a matrix inversion technology. The method not only utilizes the advantage of stable signal transmission of the optical fiber, but also combines the characteristic of strain sensitivity of the piezoelectric material, and effectively overcomes the defect of serious temperature cross sensitivity of the traditional optical fiber sensor. Through preliminary calibration and joint modeling solution, high-precision and robust detection of weak bending and stretching signals in a complex temperature environment is realized, and the reliability of tactile sensing and structural health monitoring is remarkably improved.

Description

Detection and fabrication methods of tactile fiber optic sensors based on electro-optic fusion Technical Field

[0001] This invention relates to the field of biomimetic tactile technology, specifically to a detection method and fabrication method for a tactile fiber optic sensor based on electro-optic fusion. Background Technology

[0002] With the continuous development of wearable devices, wearable devices now possess flexible functions such as bending, folding, and stretching. These characteristics make flexible wearable devices highly adaptable, giving them great application potential in smart scenarios such as healthcare, sports, and daily life.

[0003] Existing flexible tactile skin typically uses piezoresistive or capacitive methods to sense normal pressure. However, these sensors suffer from zero-point drift and insufficient repeatability under temperature changes and bending conditions.

[0004] In the process of developing this invention, the inventors discovered that existing flexible tactile sensors mostly rely on a single physical quantity, electricity or light, for detection. This makes it difficult to simultaneously achieve bending, stretching, and temperature drift compensation at the microscale fiber morphology. Traditional plastic optical fibers are sensitive to bending but exhibit significant temperature drift; PVDF-type piezoelectric fibers can measure strain / stress, but suffer from complex calibration and temperature compensation issues. Summary of the Invention

[0005] One of the objectives of this invention is to provide a detection method and a fabrication method for a tactile fiber optic sensor based on electro-optic fusion, so as to solve the shortcomings of existing flexible tactile sensors that cannot be detected by a single physical quantity.

[0006] To solve the above-mentioned technical problems, the embodiments of the present invention are implemented as follows: Firstly, a detection method for a tactile fiber optic sensor based on electro-optic fusion is provided. The fiber optic sensor includes a fiber core and a cladding of an optical channel. The steps include: Step S1: Synchronously acquiring optical and electrical signals generated during mechanical bending, wherein the electrical signal is a piezoelectric charge signal generated by strain in the electrical channel, and the optical signal is the light intensity signal transmitted by the optical beam in the optical channel; Step S2: Calculating the light intensity deviation value based on the light intensity change signal, and calculating the voltage deviation value based on the voltage change signal; Step S3: Obtaining the preliminary curvature of the optical channel based on a preset quantitative mapping relationship and the light intensity deviation value; Step S4: Constructing a photoelectric joint model using the preliminary curvature, the light intensity deviation value, the voltage deviation value, and temperature, and expressing the photoelectric joint model by matrix inversion; Step S5: Solving the real-time light intensity deviation value and the real-time voltage deviation value through the photoelectric joint model to obtain output curvature or stretching data.

[0007] The second aspect also discloses a preparation method for fabricating the electro-optic fusion-based tactile fiber optic sensor for sensing. The steps include: preparing a pre-fabricated optical fiber; drying the fiber core and processing it into a circular core; heating and melting the cladding material and extruding it to obtain a cladding with a sleeve structure; then inserting the core into the cladding to obtain the pre-fabricated optical fiber; performing a dual-zone drawing process on the core and cladding of the pre-fabricated optical fiber; after the pre-fabricated optical fiber has undergone the drawing process, using a deposition process to fabricate an electrode layer, the electrode layer being symmetrically arranged along the axial direction of the core at the center of the outer periphery of the cladding; and polarizing the electrode layer using a high-voltage polarization process to obtain the electro-optic fusion-based tactile fiber optic sensor.

[0008] The beneficial effects of the above-mentioned technical solutions provided by the embodiments of the present invention include at least the following: The embodiments of the present invention use a flexible fiber with dual physical quantities, including optical signals and piezoelectric signals, to detect strain caused by mechanical bending, thereby solving the problem that existing flexible tactile sensors that rely on a single physical quantity are prone to temperature sensitivity crossover or complex temperature compensation.

[0009] The electro-optic fusion-based tactile fiber optic sensor detection method described in this embodiment constructs a joint sensor containing both optical and electrical channels, establishes a photoelectric joint model, and utilizes matrix inversion techniques to decouple mechanical deformation and temperature interference. This method not only leverages the stable transmission of fiber optic signals but also incorporates the strain-sensitive characteristics of piezoelectric materials, effectively overcoming the severe temperature cross-sensitivity inherent in traditional fiber optic sensors. Through preliminary calibration and joint modeling, high-precision and robust detection of weak bending and stretching signals is achieved under complex temperature environments, significantly improving the reliability of tactile sensing and structural health monitoring.

[0010] Other features and advantages of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. The objects and other advantages of the invention may be realized and obtained by means of the structures particularly pointed out in the written description and the accompanying drawings.

[0011] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0012] Figure 1 is a schematic diagram of a tactile fiber optic sensor based on electro-optic fusion provided in an embodiment of the present invention; Figure 2 is a graph of voltage signal and voltage signal curve in an embodiment of the present invention. Detailed Implementation

[0013] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0014] In this application, the term "exemplary" is used to mean "used as an example, illustration, or description." Any implementation described as "exemplary" in this application is not necessarily to be construed as being more preferred or advantageous than other implementations. The following description is provided to enable any person skilled in the art to implement and use this application. Details are listed in the following description for illustrative purposes. It should be understood that those skilled in the art will recognize that this application can be implemented without using these specific details. In other instances, well-known structures and processes are not described in detail to avoid obscuring the description of this application with unnecessary detail. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application. Bionic skin is an artificial material that simulates the structure and function of human skin through biomimetic design, aiming to replicate the sensing, protective, and self-healing properties of real skin. It is typically made of elastic polymer composite materials (such as silicone-based polymers), possessing flexibility, stretchability, and biocompatibility. Its core functions include sensing external stimuli such as pressure, temperature, and humidity, and converting this information into electrical signals for use in fields such as robotic sensing, intelligent prosthetics, and medical monitoring. For example, bionic electronic skin can endow robots with tactile abilities, enhancing the human-computer interaction experience. Bionic skin has enormous application potential in consumer electronics, military, and healthcare industries. With the development of flexible electronics, novel attachable, wearable, portable, and foldable flexible electronic devices have become an important development direction in recent years.

[0015] Among them, tactile sensors play a core role in bionic skin. By simulating the tactile perception mechanism of human skin, bionic skin can detect and respond to mechanical stimuli from the external environment, including pressure, shear force, and vibration, as well as physical properties such as temperature, humidity, and texture.

[0016] Existing tactile sensors struggle to combine electrical and optical physical quantities for detection while maintaining a simple structure. Traditional plastic optical fibers are sensitive to bending but exhibit significant temperature drift; PVDF-type piezoelectric fibers can measure strain / stress, but suffer from complex calibration and temperature compensation issues. Furthermore, neither of these types of sensors can combine electrical and optical physical quantities for detection.

[0017] Before describing the embodiments of the present invention in detail, the design concept of the present invention will be summarized below.

[0018] This invention provides a tactile fiber optic sensor based on electro-optic fusion, with the specific implementation as follows. As shown in Figure 1, the core of this invention includes: a double-layer coaxial fiber structure is obtained by wrapping a PVDF cladding around the core of a COP fiber. The core is made of COP. When bending occurs, the light intensity changes due to the deformation of the core. By detecting the change in light intensity or charge signal, the corresponding strain can be obtained. Furthermore, symmetrical electrodes are arranged on the outer surface of the cladding. When bending, the electrodes generate charge signals based on the mechanical deformation of the fiber. By detecting the charge signals, strain / tension can be detected. Additionally, the refractive index of the core is greater than that of the cladding to form a total internal reflection waveguide channel, thereby improving the bending sensitivity of the sensor and reducing loss. The tactile sensor structure designed in this invention integrates optical and piezoelectric signals within the same fiber, improving robustness and accuracy through signal redundancy and joint modeling.

[0019] Based on the same inventive concept, a first aspect also discloses, with reference to Figure 1, a tactile fiber optic sensor based on electro-optic fusion, comprising: a core for beam delivery; a cladding disposed on the outer periphery of the core; and an electrode layer disposed on the outer periphery of the cladding, the electrode layer comprising at least one set of electrodes, and the electrodes being symmetrically arranged on both sides of the cladding about the central axis of the core, for generating a positive piezoelectric effect according to mechanical deformation; wherein, the refractive index of the core is higher than the refractive index of the cladding.

[0020] Understandably, in order to enable a flexible fiber to have dual physical quantities, including optical signals and piezoelectric signals, to detect strain caused by mechanical bending, thereby solving the problem that existing flexible tactile sensors that rely on a single physical quantity are prone to temperature sensitivity crossover or complex temperature compensation.

[0021] In this embodiment, a double-layer coaxial fiber structure is obtained by wrapping a PVDF cladding around the core of a COP fiber. The core is made of COP. When bending occurs, the light wave drifts due to the deformation of the core. By detecting the change in light intensity or charge signal of the beam, the corresponding strain can be obtained. Furthermore, symmetrical electrodes are arranged on the outer surface of the cladding. During bending, the electrodes generate charge signals based on the mechanical deformation of the fiber. By detecting these charge signals, strain / tension can be detected. Additionally, the refractive index of the core is greater than that of the cladding to form a total internal reflection waveguide channel, thereby improving the bending sensitivity of the sensor and reducing loss.

[0022] Metal electrodes are formed on the outer surface of the cladding made of PVDF, wherein the metal electrodes include at least one pair and are symmetrically arranged along the axis of the optical fiber, such that the electrodes form an electrical channel for piezoelectric sensing. This electrical channel can detect the strain or tensile amount of the optical fiber by responding to piezoelectric charge or voltage.

[0023] The core is made of a material with a high refractive index, such as COP fiber core n≈1.53@1550nm, while the cladding is made of a material with a low refractive index, such as n≈1.42, to ensure total internal reflection and low-loss transmission.

[0024] In this embodiment, the electrode layer comprising at least one set of electrodes means that the electrode layer comprises at least one set of electrodes, wherein one set of electrodes consists of two electrodes arranged symmetrically at the center.

[0025] In some embodiments, the electrode layer consists of two electrodes, which are symmetrically arranged on both sides of the cladding surface; in other embodiments, the electrode layer consists of four electrodes, which are evenly distributed on the cladding surface; and in still other embodiments, the electrode layer consists of six electrodes, which are evenly distributed on the cladding surface.

[0026] Working process: The core of COP is embedded in the cladding made of PVDF to form the optical fiber of the touch sensor, and the refractive index of the core is ensured to be higher than that of the cladding. An electrode layer is also set on the outside of the cladding.

[0027] In this embodiment, a laser source and a photodetector are used to detect the tactile fiber sensor. When pressure is applied to the optical fiber, the fiber bends, causing the fiber core to bend and thus sending strain through the core. The light wave drift can be detected by a photodetector or other device, or the voltage change of the core can be detected by a photodetector. The cladding also undergoes mechanical bending at the same time. At this time, the electrode layer located outside the cladding also bends along with the cladding. That is, when pressure is applied to the fiber, the internal lattice deformation of the material causes charge separation and generates voltage. The voltage signal of the electrode is detected by a photodetector.

[0028] In a further embodiment, the core is made of a cyclic olefin copolymer and has a diameter controlled to be 6-20 μm.

[0029] Understandably, in order to make the refractive index of the core higher than that of the cladding and reduce loss, in this embodiment, a cyclic olefin copolymer is used to make the core to obtain COP optical fiber, and the diameter of the core should be controlled.

[0030] In some embodiments, a COP core is made of polymer and the refractive index n≈1.53@1550 nm is controlled, and the diameter of the core is controlled to be 16 μm; in other embodiments, a COP core is made of polymer and the refractive index n≈1.53@1550 nm is controlled, and the diameter of the core is controlled to be 6 μm; in still other embodiments, a COP core is made of polymer and the refractive index n≈1.53@1550 nm is controlled, and the diameter of the core is controlled to be 20 μm.

[0031] In a further embodiment, the cladding is made of one of polyvinylidene fluoride (PVDF) or the copolymer PVDF-TrFE, and the thickness is controlled to be 50–125 μm.

[0032] Understandably, in order for the cladding to function as a piezoelectric fiber and have a refractive index lower than that of the core, in this embodiment, the cladding is made from raw materials including polyvinylidene fluoride (PVDF) or the copolymer PVDF-TrFE, and the thickness of the cladding is controlled within a certain range.

[0033] In some embodiments, the cladding is made of PVDF, the thickness of the cladding is controlled at 100 μm, and the refractive index n of the cladding is approximately 1.42; in other embodiments, the cladding is made of PVDF-TrFE, the thickness of the cladding is controlled at 50 μm, and the refractive index n of the cladding is approximately 1.42; in still other embodiments, the cladding is made of PVDF, the thickness of the cladding is controlled at 125 μm, and the refractive index n of the cladding is approximately 1.42.

[0034] As described above, the core is made of a material with a high refractive index, such as COP fiber with a core refractive index n of approximately 1.53 at 1550 nm, while the cladding is made of a material with a low refractive index, such as PVDF with a refractive index n ≈ 1.42, ensuring total internal reflection and low-loss transmission. Alternatively, the core can be made of polymethyl methacrylate (PMMA), with a refractive index of 1.49, which is higher than that of the cladding.

[0035] In a further embodiment, the electrode layer is made of a material including Ti / Au, Cr / Au or Al, and the thickness of the electrode layer is controlled to be 100-300 nm.

[0036] Based on the same inventive concept, a second aspect provides a sensor detection method using the aforementioned deformation detection method based on an electro-optical fusion-based tactile fiber optic sensor. The steps include: Step 1: Simultaneously acquiring optical and electrical signals generated during mechanical bending, wherein the electrical signal is a piezoelectric charge signal generated by strain in the electrical channel, and the optical signal is the light intensity signal transmitted by the light beam in the optical channel. In an embodiment, the electro-optical fusion-based tactile fiber optic sensor employs a special structural design, comprising an optical fiber core, an optical channel for transmitting optical signals, and a piezoelectric material layer coated on the outer cladding of the optical fiber for sensing strain in the electrical channel. When the fiber optic sensor is subjected to external force and undergoes mechanical bending, the light beam in the optical channel changes intensity due to micro-bending loss, while the electrical channel generates a piezoelectric charge signal due to the piezoelectric effect, which is then converted into a voltage signal.

[0037] In this embodiment, a photodetector acquires optical and charge signals generated by a tactile fiber optic sensor based on electro-optic fusion when mechanical deformation occurs. These two signals include the fiber strain signal of the core and the bending strain signal of the cladding. The fiber strain signal of the core is obtained by detecting the difference in light intensity change of the reflected beam within the core when mechanical deformation occurs, thus obtaining the deviation value of the core's light intensity. The bending strain signal of the cladding is obtained by detecting the voltage deviation of the cladding when the fiber is subjected to external pressure or tension during mechanical deformation, causing deformation of its internal crystal structure, resulting in charge redistribution and voltage generation across the material.

[0038] In practical applications, such as installing this sensor on the fingertip of a robot, when the finger bends to grasp an object, the data acquisition card needs to simultaneously acquire the voltage signal converted from the light intensity change of the optical channel by a photodiode and the voltage signal converted from the piezoelectric charge of the electrical channel by a charge amplifier, with extremely high time synchronization accuracy (e.g., microsecond level). Synchronous acquisition ensures that the optical and electrical signals correspond to the mechanical deformation state at the same moment in subsequent steps, avoiding calculation errors caused by time misalignment.

[0039] Step 2: Calculate the light intensity deviation value based on the light intensity change signal, and calculate the voltage deviation value based on the voltage change signal.

[0040] In this example, the aim is to remove the DC component and extract the variation in preparation for subsequent normalization processing.

[0041] When the sensor is not under force or is in a reference state (such as a flat state), the system first records the reference light intensity. and reference voltage .

[0042] When the sensor is working, the system collects the current light intensity in real time. and current voltage .

[0043] Light intensity deviation value The calculation formula is: Alternatively, to eliminate the influence of light source fluctuations, normalized bias can be used. .

[0044] voltage deviation The calculation formula is: .

[0045] By calculating the deviation value, the system focuses on signal changes caused by mechanical deformation, filtering out static errors caused by non-deformation factors such as slow changes in ambient light or circuit zero-point drift.

[0046] Step 3: Based on the preset quantitative mapping relationship and the deviation value of the light intensity, obtain the preliminary curvature of the optical channel.

[0047] In this example, the high sensitivity of optical signals is used to quickly obtain a preliminary estimate of curvature and establish a physical relationship between optical loss and curvature.

[0048] First, using the light intensity loss formula Calculate the loss value corresponding to the deviation in light intensity. ,in, As the reference light intensity, This represents the current light intensity.

[0049] Secondly, the loss value is determined using a pre-defined quantitative mapping relationship. It is converted into a preliminary curvature.

[0050] The process of establishing the quantitative mapping relationship (calibration process) is as follows: using known curvature A series of standard bending molds, such as semi-cylinders with radii of 10mm, 20mm, and 50mm, are used to fix fiber optic sensors onto the molds and measure the output light intensity under different curvatures. The light intensity set is obtained. The corresponding light intensity loss value set is calculated using the light intensity loss formula. Subsequently, a curve fitting model (such as least squares fitting) is established to fit the loss value set to obtain a quantitative mapping relationship between the loss value and the curvature. For example, the calibration curve equation can be obtained through fitting, such as the linear approximation formula. Or more complex nonlinear relationship formulas ,in Here are the inherent parameters of the optical fiber: a is the linear sensitivity coefficient, b is the inherent loss coefficient (intercept), C is the saturation loss amplitude coefficient, and D is the critical curvature characteristic coefficient.

[0051] In real-time monitoring, the calculated loss value is substituted into the calibration curve equation to obtain the preliminary curvature. Although this preliminary curvature is greatly affected by temperature, it provides a key reference for the magnitude of curvature.

[0052] Step 4: Construct a photoelectric joint model using the initial curvature, light intensity deviation, voltage deviation, and temperature, and then express the photoelectric joint model by matrix inversion.

[0053] In this embodiment, a photoelectric joint model is established by using the initial curvature, the deviation value of light intensity, the deviation value of voltage, and temperature to establish a linearized joint model. The photoelectric joint model is then expanded and expressed in reverse. The curvature is calculated using a calibration matrix, and the influence of temperature on the measurement results is suppressed. This is used to suppress temperature interference and achieve temperature-robust curvature / tension measurement.

[0054] First, a preliminary system is established using deviations in curvature, light intensity, voltage, and temperature. Linearized joint model; where, The deviation value of the normalized light intensity of the optical channel of the core is the deviation measured by a photodetector; The deviation of the voltage of the electrical channel of the cladding is measured by a photodetector. The curvature to be estimated, or the equivalent bending angle; For temperature deviation; A is the sensitivity calibration matrix, i.e. ,in For calibration coefficients, and These are the pressure sensitivity coefficients of the core and cladding, respectively. and These are the temperature sensitivity coefficients of the core and cladding, respectively.

[0055] Matrix temperature compensation is achieved by using a linearized joint model of curvature κ and temperature ΔT with ΔI and ΔV.

[0056] Next, the linearized joint model is expanded to obtain the expanded formula, as follows:

[0057] Finally, the expanded formula is expressed in reverse.

[0058]

[0059]

[0060] in, .

[0061] Step 5: Solve the real-time light intensity deviation and the real-time voltage deviation using a photoelectric joint model to obtain the output curvature or stretching data.

[0062] In this example, the constructed inverse model is used for real-time calculation, and the final high-precision measurement result is output.

[0063] The embodiment uses the real-time detected bending strain, i.e., the real-time deviation value calculated in step S2. and Substitute this into the formula for the inverse expression of the photoelectric joint model.

[0064] In this embodiment, the deviation values ​​of light intensity and voltage obtained by using a photodetector, along with A as the sensitivity calibration matrix, are substituted into the joint model expressed in reverse. Here, A, the sensitivity calibration matrix, includes the pressure sensitivity coefficient and temperature sensitivity coefficient of the core and cladding.

[0065] The specific calculation process involves matrix multiplication:

[0066]

[0067] Using the above formula, the system can directly calculate the true curvature after eliminating temperature interference. If the sensor is configured for tensile measurement, such as when an optical fiber is attached to the surface of an elastomer, the curvature can be further converted into tensile strength.

[0068] For example, in high temperature environments ( ), optical signal The increased light intensity due to thermal expansion may create a false "negative bending" trend. However, the piezoelectric signal at this time... If not stretched, it remains unchanged. In the model... Project will utilize The invariance of the property to offset Zhongyou The resulting changes will ultimately output the correct value. value.

[0069] Finally, the calculated curvature or stretching data is output to the display terminal or control unit to complete the detection process.

[0070] Step 6: Obtain the corresponding mechanical deformation based on the curvature.

[0071] Understandably, the embodiment accurately decouples mechanical deformation (curvature) and thermal effects from simple electrical measurements, which is a common and effective signal processing method in flexible sensor systems.

[0072] Figure 2 shows the voltage signal curves of the piezoelectric fiber in the cladding and the voltage signal curves of the core detected by photoelectric detection. As can be seen from the figure, the two piezoelectric signal curves change with the bending angle.

[0073] The electro-optic fusion-based tactile fiber optic sensor detection method described in this embodiment constructs a joint sensor containing both optical and electrical channels, establishes a photoelectric joint model, and utilizes matrix inversion techniques to decouple mechanical deformation and temperature interference. This method not only leverages the stable transmission of fiber optic signals but also incorporates the strain-sensitive characteristics of piezoelectric materials, effectively overcoming the severe temperature cross-sensitivity inherent in traditional fiber optic sensors. Through preliminary calibration and joint modeling, high-precision and robust detection of weak bending and stretching signals is achieved under complex temperature environments, significantly improving the reliability of tactile sensing and structural health monitoring.

[0074] Based on the same inventive concept, a third aspect also discloses a preparation method for fabricating the electro-optic fusion-based tactile fiber optic sensor, the steps of which include: Step 001: Prefabricating a pre-fiber by drying the fiber core and processing it into a circular core, heating and melting the cladding material and extruding it to obtain a cladding with a sleeve structure, and then inserting the core into the cladding to obtain the pre-fiber.

[0075] In a further embodiment, the optical fiber core material is dried and processed into a circular core by placing the optical fiber core material in a drying device at 80°C for 12 hours to dehumidify; the cladding material is heated, melted, and then extruded to obtain a cladding structure by placing the cladding material at 160–180°C for melting, and then using an extrusion process to form a cladding structure with an inner diameter 0.05–0.2 mm larger than the core rod.

[0076] Then, a cylindrical core is inserted into the PVDF cladding, followed by degassing in a vacuum environment (–0.09 MPa) for 30 min to remove interfacial bubbles. The PVDF cladding is then pre-polarized for 10–30 min under an electric field of 40–60 MV / m and a temperature of 90–100°C to form a β-phase crystalline region, thereby improving the subsequent piezoelectric coefficient. Pre-fabricated optical fibers are obtained.

[0077] Step 002: The core and cladding of the prefabricated optical fiber are drawn in two zones using a drawing process.

[0078] Furthermore, the dual-zone drawing process for the core and cladding of the prefabricated optical fiber involves setting the upper zone temperature using a drawing tower. The temperature is controlled at 100-160°C for drawing the corresponding core, and the lower zone temperature is... The temperature is controlled at 170-220°C for drawing the corresponding cladding layers; and and The temperature difference ΔT is controlled between 40-70°C.

[0079] For example: A drawing tower is used to draw pre-fabricated optical fibers, and the upper zone temperature of the drawing tower is set. The temperature range is 100–160°C, corresponding to the COP softening point, and the lower zone temperature. The operating temperature is 170-220°C, suitable for stretchable PVDF windows. And... and The temperature difference ΔT is controlled at 40-70°C to avoid interfacial stress delamination. During fiber drawing, the traction rate is set to 5-20 m / min, the tension to 20-80 g, and the stretching speed ratio to 1.2-1.8. During fiber drawing, the core diameter is controlled at 6–20 μm and the cladding thickness at 10–40 μm using real-time online outer diameter monitoring (laser diameter gauge). The distance from the fiber exit to the cooling zone is 30-50 cm, and sizing cooling is performed using nitrogen or clean air at a flow rate of 0.3-0.8 m / s to prevent optical interface scattering. The fiber is wound onto a polyimide reel with uniform tension to avoid helical twisting.

[0080] Step 003: After the pre-fabricated optical fiber undergoes the drawing process, an electrode layer is fabricated using a deposition process. The electrode layer is symmetrically arranged at the center of the outer periphery of the cladding along the axial direction of the core.

[0081] In a further embodiment, when fabricating the electrode layer using a deposition process, firstly, the pre-fabricated optical fiber is used... The process involves cleaning with plasma; then, electrodes are deposited on only the symmetrical sides of the pre-fabricated optical fiber using a mechanical shielding or photolithography method, with the electrode width occupying approximately 30°-60° of the circumference; finally, an insulating layer is formed around the metal electrodes.

[0082] For example: using fiber optic cables after drawing Plasma cleaning at 100 W power for 30 seconds enhances electrode metal adhesion. A bilayer structure of Ti / Au (10 nm / 200 nm) or Cr / Al (20 nm / 300 nm) is deposited to ensure a balance between conductivity and flexibility. Electrodes are deposited only on symmetrical sides of the fiber using a rotating optical fiber and a mechanical shielding method (or photolithography), with the electrode width occupying approximately 30°-60° of the circumference. Finally, a transparent insulating layer of fluorinated polymer or Parylene film is coated onto the metal electrodes, with the insulating layer thickness controlled to <2 μm for insulation and corrosion protection.

[0083] Step 004: The electrode layer is polarized using a high-voltage polarization process to obtain a tactile fiber optic sensor based on electro-optic fusion.

[0084] Furthermore, the polarization treatment of the electrode layer using a high-voltage polarization process involves subjecting the prefabricated optical fiber after electrode deposition to high-voltage polarization, with the polarization temperature controlled at 80–120°C, the electric field strength controlled at 80–120 MV / m, and the polarization time lasting 1–20 min.

[0085] For example, after the electrodes are deposited, the optical fiber is subjected to high-voltage polarization. The polarization temperature is controlled at 80-120°C, the polarization electric field strength is controlled at 80-120 MV / m, and the polarization time lasts for 10-20 min.

[0086] After high-pressure polarization, the temperature will be slowly reduced to room temperature, with the rate of temperature decrease controlled at <3°C / min during cooling to stabilize molecular orientation and internal stress, and prevent [further damage]. Attenuation is achieved to obtain a tactile fiber optic sensor based on electro-optic fusion.

[0087] Based on the same inventive concept, the fourth aspect also discloses an application method of a tactile fiber optic sensor based on electro-optic fusion, which is applied in wearable health monitoring, robot tactile sensing and human-computer interaction and other application scenarios.

[0088] Obviously, those skilled in the art can make various modifications and variations to this invention without departing from its spirit and scope. This disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims. Thus, if these modifications and variations of the invention fall within the scope of the claims of the invention and their equivalents, the invention is also intended to include these modifications and variations.

Claims

1. A detection method for a tactile fiber optic sensor based on electro-optic fusion, wherein the fiber optic sensor comprises a fiber core for an optical channel and a cladding for an electrical channel, characterized in that, The steps include: Step S1: Synchronously acquiring optical and electrical signals generated during mechanical bending, wherein the electrical signal is the piezoelectric charge signal generated by the strain of the electrical channel, and the optical signal is the light intensity signal transmitted by the light beam in the optical channel; Step S2: Calculating the light intensity deviation value based on the light intensity change signal, and calculating the voltage deviation value based on the voltage change signal; Step S3: Obtaining the preliminary curvature of the optical channel based on the preset quantitative mapping relationship and the light intensity deviation value; Step S4: Constructing a photoelectric joint model using the preliminary curvature, light intensity deviation value, voltage deviation value, and temperature, and expressing the photoelectric joint model by matrix inversion; Step S5: Solving the real-time light intensity deviation value and the real-time voltage deviation value through the photoelectric joint model to obtain the output curvature or stretching data.

2. The detection method according to claim 1, characterized in that, Step S3 includes: calculating the loss value corresponding to the deviation value of the light intensity using the light intensity loss formula; substituting the loss value into the quantitative mapping relationship, and solving the preliminary curvature through the quantitative mapping relationship.

3. The detection method according to claim 1 or 2, characterized in that, The quantitative mapping relationship is established based on the relationship between light intensity loss and bending degree. The steps include: using an optical fiber bending device with known curvature, fixing the optical fiber sensor on the mold, measuring the output light intensity under different curvatures to obtain a light intensity set; calculating the loss value set corresponding to the light intensity set using the light intensity loss formula; establishing a curve fitting model, and fitting the loss value set using the curve fitting model to obtain the quantitative mapping relationship between the loss value and the bending curvature.

4. The detection method according to claim 1, characterized in that, In step S4, the construction of the photoelectric joint model and the matrix inversion expression of the photoelectric joint model are as follows: a linearized photoelectric joint model is established based on the initial curvature, the deviation value of light intensity, the deviation value of voltage and temperature, and the photoelectric joint model is expanded and expressed inversely. The curvature is calculated using the calibration matrix and the influence of temperature on the measurement results is suppressed. This is used to suppress temperature interference and realize temperature-robust curvature / tension measurement.

5. The detection method according to claim 4, characterized in that, The photoelectric joint model is as follows: Linearized joint model; where, This represents the deviation value of the normalized light intensity of the optical channel in the core. This represents the voltage deviation of the electrical path in the cladding. The curvature to be estimated; denoted as temperature deviation; A is the sensitivity calibration matrix.

6. A method for fabricating a tactile sensor, characterized in that, The steps for fabricating a tactile sensor based on electro-optic fusion include: preparing a pre-fabricated optical fiber; drying the fiber core and processing it into a circular core; heating and melting the cladding material and extruding it to obtain a cladding with a sheath structure; then inserting the core into the cladding to obtain the pre-fabricated optical fiber; performing a dual-zone drawing process on the core and cladding of the pre-fabricated optical fiber; after the pre-fabricated optical fiber has undergone the drawing process, using a deposition process to fabricate an electrode layer, which is symmetrically arranged along the axial direction of the core at the center of the outer periphery of the cladding; and polarizing the electrode layer using a high-voltage polarization process to obtain the tactile fiber sensor based on electro-optic fusion.

7. The preparation method according to claim 6, characterized in that, The process of drying the optical fiber core material to form a circular core involves placing the optical fiber core material in a drying device at 80°C for 12 hours to dehumidify it. The process of heating and melting the cladding material and then extruding it to obtain a cladding structure involves placing the cladding material at 160–180°C for melting and then using an extrusion process to form a cladding structure with an inner diameter 0.05–0.2 mm larger than the core rod.

8. The preparation method according to claim 6, characterized in that, The process of using a drawing process to draw the core and cladding of the prefabricated optical fiber in two zones involves: using a drawing tower to set the upper zone temperature T1 to 100-160°C for drawing the core, and the lower zone temperature T2 to 170-220°C for drawing the cladding; and controlling the temperature difference ΔT between T1 and T2 to 40-70°C.

9. The preparation method according to claim 6, characterized in that, When fabricating the electrode layer using the deposition process, firstly, the prefabricated optical fiber is cleaned using O2 plasma; then, electrodes are deposited only on both symmetrical sides of the prefabricated optical fiber using a mechanical shielding or photolithography method, with the electrode width occupying approximately 30°-60° of the circumference; finally, an insulating layer is fabricated outside the metal electrodes.

10. The preparation method according to claim 6, characterized in that, The process of polarizing the electrode layer using a high-voltage polarization process involves subjecting the prefabricated optical fiber after electrode deposition to high-voltage polarization. The polarization temperature is controlled at 80–120°C, the electric field strength is controlled at 80–120 MV / m, and the polarization time lasts for 10–20 min.

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