Optical fiber force sensor integrated with a spinal cord electrical stimulation electrode and safe delivery method

Abstract

This application provides a fiber optic force sensor integrated into a spinal cord electrical stimulation electrode and a safe delivery method. The sensor utilizes an elastic sleeve at the electrode tip, with multiple circumferentially spaced elastic deformation units forming an elastic deformation zone. The outer wall of the electrode has multiple axially extending receiving grooves into the elastic sleeve. Placing the FBG sensing fiber within these grooves positions the grating region within the elastic deformation zone, thus converting axial force into local strain. Based on this structure, this application achieves real-time three-dimensional force sensing at the electrode tip, compensating for the inadequacy of the surgeon's tactile signal and reducing the risk of iatrogenic injury. Simultaneously, the electromagnetic interference resistance of FBG solves the problem of co-integration with active stimulation electrodes. Furthermore, using the elastic sleeve as the mounting substrate avoids viscoelastic hysteresis and creep, improving measurement repeatability. The elastic deformation units overcome the problem of low axial force resolution due to high axial stiffness, improving the accuracy of three-dimensional force decoupling.

Description

Technical Field

[0001] This application generally relates to the field of spinal cord electrode technology, and specifically to an optical fiber force sensor integrated into a spinal cord electrical stimulation electrode and a safe delivery method thereon. Background Technology

[0002] Spinal cord stimulation (SCS) therapy, which modulates neural activity by implanting electrodes into the epidural space and applying electrical pulses, is an important method for treating chronic pain and promoting functional reconstruction after spinal cord injury. SCS electrodes are typically delivered percutaneously, with the operator guiding the flexible electrode through a puncture needle to the target segment of the epidural space under X-ray guidance. The epidural space, with an anteroposterior diameter of only 3-5 mm, contains various structures such as adipose tissue, venous plexuses, and spinal nerve roots, exhibiting complex anatomical layers and significant individual variations. During electrode delivery, contact and collision with the space wall tissue are inevitable. Therefore, integrating force sensing functionality at the electrode tip to achieve real-time monitoring of contact force is crucial for assisting the operator in assessing the tip's condition and preventing iatrogenic injury.

[0003] However, existing SCS electrodes do not integrate tip force sensing functionality. Operators rely solely on indirect tactile sensation at the operating end to judge the tip's state. The signal is severely distorted after long-distance transmission through the flexible electrode, making it difficult to identify abnormal resistance in a timely manner. Postoperative complication rates are as high as 30%-40%. The main reasons are: SCS electrodes need to be delivered through a 14G puncture needle (with an inner diameter of approximately 1.7 mm). Traditional resistance strain gauge, piezoelectric, and MEMS sensors are difficult to miniaturize due to their complex wiring and large packaging size. At the same time, the electrodes need to transmit high-frequency, high-voltage stimulation pulses, and traditional electrical sensors are highly susceptible to electromagnetic interference and may fail. While fiber Bragg grating (FBG) sensors offer advantages such as small diameter and resistance to electromagnetic interference, directly attaching an FBG sensor to the surface of a flexible electrode can lead to hysteresis and creep due to the viscoelasticity of the substrate. The axial stiffness of the thin-walled tubular electrode is much greater than its radial bending stiffness, resulting in minimal deformation under axial force and extremely low resolution of the FBG sensor for axial forces. Furthermore, the flexible electrode is prone to radial buckling under axial compression, causing uneven strain distribution in the grating region of the FBG sensor, introducing nonlinear errors, and severely affecting the accuracy of three-dimensional force decoupling. Summary of the Invention

[0004] In view of the above-mentioned defects or deficiencies in the prior art, it is desirable to provide an optical fiber force sensor integrated into a spinal cord electrical stimulation electrode and a safe delivery method that can solve the above-mentioned technical problems.

[0005] In a first aspect, this application provides a fiber optic force sensor integrated into a spinal cord electrical stimulation electrode, comprising: An elastic sleeve is disposed on one side of the electrode tip, and the elastic sleeve is connected to the electrode tip; An elastic deformation zone is provided on the elastic sleeve. The elastic deformation zone has multiple elastic deformation units, which are provided on the elastic sleeve and spaced apart circumferentially along the outer wall of the elastic sleeve. The elastic deformation units are used to reduce the axial stiffness of the elastic sleeve. The receiving groove is provided in multiple ways, each receiving groove is provided on the outer wall of the electrode and extends along its axial direction to the elastic sleeve; The FBG sensing fiber is provided in multiple ways, and each FBG sensing fiber has an FBG grating region. The FBG sensing fibers are respectively disposed in the corresponding receiving grooves, and the FBG grating regions are located in the elastic deformation region for sensing the deformation of the elastic deformation region.

[0006] According to the technical solution provided in this application, each elastic deformation unit includes a plurality of deformation holes, and the plurality of deformation holes are arranged at intervals along the axial direction of the elastic sleeve; The deformable hole has two end circular hole sections located at its two ends, and an intermediate gradient section located between the two end circular hole sections; both end circular hole sections are circular holes of equal diameter; the axial height of the intermediate gradient section along the elastic sleeve gradually decreases from its middle part to both sides, and the two ends of the intermediate gradient section are smoothly connected to the end circular hole sections on the corresponding sides.

[0007] According to the technical solution provided in this application, the elastic deformation units are arranged symmetrically in pairs, and the deformation holes of two adjacent elastic deformation units are staggered. The deformation holes of the two symmetrically arranged elastic deformation units are arranged one-to-one to prevent the elastic sleeve from buckling radially when it is compressed.

[0008] According to the technical solution provided in this application, each of the FBG sensing optical fibers is fixedly connected to the receiving groove, and the FBG grating region of each of the FBG sensing optical fibers is movably disposed within the corresponding elastic deformation region.

[0009] According to the technical solution provided in this application, the elastic sleeve and the electrode tip are connected by an insulating component, which is used to isolate the elastic sleeve from the active stimulation wire inside the electrode.

[0010] According to the technical solution provided in this application, four FBG sensing optical fibers are provided, and the four FBG sensing optical fibers are equally spaced along the outer wall of the elastic sleeve.

[0011] Secondly, this application provides a secure delivery method based on a fiber optic force sensor, which is implemented using the fiber optic force sensor integrated into the spinal cord electrical stimulation electrode as described in the first aspect. The fiber optic force sensor is connected to a fiber optic demodulator, and the fiber optic demodulator is connected to the control device. The method includes the following steps: During the delivery of spinal cord electrical stimulation electrodes, the real-time wavelength drift of each FBG sensing fiber is acquired in real time using an optical fiber demodulator. The real-time wavelength drift is then used to construct a column vector, and the column vector is multiplied by a decoupling matrix to obtain the three-dimensional contact force and ambient temperature change values. The three-dimensional contact force includes at least axial force. The decoupling matrix is ​​obtained by inverting a calibration sensitivity matrix, which is established based on the linear combination relationship between the wavelength drift of each FBG sensing fiber and the three-dimensional contact force and ambient temperature change values. If the axial force is determined to be greater than or equal to the overload warning threshold, an overload warning signal is issued and the recursion speed is adjusted.

[0012] According to the technical solution provided in this application, the method further includes: Known static loads in a first direction, a second direction, and a third direction are applied to the fiber optic force sensor, respectively, and the wavelength shift of the reflection center of the four FBG sensing fibers is collected at different ambient temperatures; the first direction, the second direction, and the third direction are perpendicular to each other; Using the known static load force value and ambient temperature change value as independent variables, and the four wavelength drift values ​​as dependent variables, the sensitivity coefficients of the first direction, the second direction, and the third direction, as well as the temperature sensitivity coefficient, are obtained by least squares fitting, and a calibration sensitivity matrix is ​​established. The decoupling matrix is ​​obtained by inverting the calibration sensitivity matrix.

[0013] According to the technical solution provided in this application, the following steps are also included: If it is determined that the axial force is less than the overload warning threshold, then it is determined whether the axial force is greater than or equal to the contact threshold; wherein the contact threshold is less than the overload warning threshold. If so, calculate the load change rate based on the axial force and determine whether the load change rate is greater than the impact threshold. If the load change rate is greater than the impact threshold, it is determined to be a tip obstruction event, and an obstruction warning signal is issued. If the load change rate is less than or equal to the impact threshold, it is determined to be a tip contact state, and a contact state warning signal is issued.

[0014] According to the technical solution provided in this application, the following steps are also included: The deflection angle and azimuth angle of the electrode tip are calculated based on the three-dimensional contact force, so that the operator can adjust the pushing direction.

[0015] The beneficial effects of this application are as follows: This application provides a fiber optic force sensor integrated into a spinal cord electrical stimulation electrode and a safe delivery method. The fiber optic force sensor has an elastic sleeve at the electrode tip, and multiple circumferentially spaced elastic deformation units on the elastic sleeve, which together form an elastic deformation zone. Simultaneously, multiple axially extending receiving grooves are provided on the outer wall of the electrode to the elastic sleeve, and multiple FBG sensing fibers are respectively placed in the corresponding receiving grooves, with the FBG grid area located within the elastic deformation zone. The multiple elastic deformation units collectively reduce the axial stiffness of the elastic sleeve, converting small axial displacements into local strain at the elastic deformation zone. Since the FBG grid area is located within the elastic deformation zone, it can effectively sense this local strain.

[0016] Based on the above structure, this application achieves real-time three-dimensional force sensing at the tip of the SCS electrode by integrating FBG sensing fiber at the electrode tip. This effectively compensates for the severe signal distortion when the surgeon relies on tactile sensation between the operating ends to judge the tip status, fundamentally reducing the risk of iatrogenic injuries such as dural puncture and nerve root damage. At the same time, the FBG sensing fiber itself is thin and inherently resistant to electromagnetic interference, fundamentally solving the problem that traditional electrical sensors cannot be co-integrated with active stimulation electrodes and are susceptible to interference from electrical stimulation pulses. In addition, using an elastic sleeve as the mounting base for the FBG sensing fiber avoids the viscoelastic hysteresis and creep problems caused by directly pasting the FBG sensing fiber to the surface of the flexible electrode, ensuring the repeatability and response speed of force measurement. Furthermore, the elastic deformation unit overcomes the technical obstacle of extremely low axial force resolution caused by the large axial stiffness of thin-walled tubular electrodes by reducing the local axial stiffness of the elastic sleeve. The elastic sleeve maintains the structural stability of the sensing section, avoiding radial buckling deformation when the flexible electrode is subjected to axial force, further improving the accuracy of three-dimensional force decoupling. Attached Figure Description

[0017] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of an optical fiber force sensor integrated into a spinal cord electrical stimulation electrode, provided in Embodiment 1 of this application; Figure 2 yes Figure 1 A schematic diagram of part A in the middle; Figure 3 This is a schematic diagram of the fiber optic force sensor provided in Embodiment 1 of this application without the FBG sensing fiber installed; Figure 4 yes Figure 3A schematic diagram of Part B; Figure 5 This is a schematic diagram of the FBG sensing optical fiber provided in Embodiment 1 of this application; Figure 6 This is a schematic diagram showing the connection between the elastic sleeve and the electrode provided in Embodiment 1 of this application via an insulating component; Figure 7 yes Figure 1 Top view; Figure 8 This is a flowchart of a secure delivery method based on an optical fiber force sensor provided in Embodiment 2 of this application.

[0018] In the figure: 1. Elastic sleeve; 2. Insulating component; 3. Electrode tip; 4. Elastic deformation unit; 41. Deformation hole; 411. End circular hole section; 412. Middle gradient section; 5. Receiving groove; 6. FBG sensing fiber; 61. FBG grid area; 7. UV adhesive. Detailed Implementation

[0019] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and not intended to limit it. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0020] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0021] Example 1 Please refer to Figures 1-7 This application provides a fiber optic force sensor integrated into a spinal cord electrical stimulation electrode, comprising: Elastic sleeve 1 is disposed on one side of electrode tip 3 and is connected to electrode tip 3. An elastic deformation zone is provided on the elastic sleeve 1. The elastic deformation zone has multiple elastic deformation units 4. The multiple elastic deformation units 4 are provided on the elastic sleeve 1 and are spaced apart along the outer wall of the elastic sleeve 1. The elastic deformation units 4 are used to reduce the axial stiffness of the elastic sleeve 1. The receiving groove 5 is provided in multiple ways. Each receiving groove 5 is provided on the outer wall of the electrode and extends along its axial direction to the elastic sleeve 1. Multiple FBG sensing optical fibers 6 are provided, and each FBG sensing optical fiber 6 has an FBG grid area 61. The FBG sensing optical fibers 6 are respectively disposed in the corresponding receiving groove 5, and the FBG grid area 61 is located in the elastic deformation area to sense the deformation of the elastic deformation area.

[0022] Specifically, such as Figure 1 As shown, the fiber optic three-dimensional force sensor is integrated into the electrode tip 3, without occupying the central wire channel inside the electrode, thus ensuring the integrity of the electrical stimulation function.

[0023] In this embodiment, the elastic sleeve 1 is a nickel-titanium sensitizing sleeve, manufactured from a thin-walled tube of ultra-elastic nickel-titanium alloy. In this embodiment, its outer diameter is 1.3 mm, inner diameter is 0.8 mm, wall thickness is 0.25 mm, and total length is 10 mm. The elastic sleeve 1 serves as the mounting base for the FBG sensing fiber 6. Because it uses a metallic elastomer material, it fundamentally avoids the viscoelastic hysteresis and creep problems caused by directly bonding the FBG sensing fiber 6 to the surface of a flexible polymer material, thus ensuring the repeatability and response speed of force measurement.

[0024] Specifically, the receiving groove 5 is disposed on the outer wall of the electrode and extends axially to the outer wall of the elastic sleeve 1 to accommodate the FBG sensing fiber 6. Multiple receiving grooves 5 are arranged circumferentially along the outer wall of the electrode, and each FBG sensing fiber 6 passes through the corresponding receiving groove 5, with its FBG grid region 61 located within the elastic deformation region.

[0025] In this embodiment, as Figure 3 , Figure 4 and Figure 5 As shown, the receiving groove 5 is arranged in a one-to-one correspondence with the elastic deformation unit 4, and the receiving groove 5 is connected to the elastic deformation unit 4. Since the elastic deformation unit 4 usually has the greatest stress concentration in its middle part (i.e., the center position of the deformation hole 41) when it deforms, the FBG grid region 61 of the FBG sensing fiber 6 is set in the middle position of the corresponding elastic deformation unit 4, and the FBG grid region 61 is movable in the elastic deformation unit 4 (i.e., it is not glued), so as to avoid local stress concentration and ensure the purity of strain transmission. At this position, the FBG grid region 61 can sense the maximum local strain, thereby enabling the sensor to obtain the highest strain response sensitivity.

[0026] This preferred embodiment is particularly suitable for scenarios where there are a large number of FBG sensing fibers 6 (e.g., four) and the sensitivity limit needs to be maximized. Of course, in other embodiments, the FBG gate region 61 can also be set at other locations within the elastic deformation region, as long as it can sense the strain generated in the elastic deformation region.

[0027] Specifically, the working principle of the fiber optic three-dimensional force sensor is as follows: When the electrode tip 3 is subjected to a three-dimensional contact force during delivery, the elastic sleeve 1 deforms under the force. When axial force acts on the elastic sleeve 1, the elastic deformation zone formed by multiple elastic deformation units 4 reduces the local axial stiffness of the sleeve, and the axial force is converted into local strain within the elastic deformation zone. When radial force acts on the elastic sleeve 1, the sleeve undergoes bending deformation, causing different strains in the FBG sensing fiber 6 at different circumferential positions. The FBG grid region 61 of each FBG sensing fiber 6 is located within the corresponding elastic deformation zone, enabling it to sense the local strain at that location and output a sensing signal in the form of reflected center wavelength drift. Thus, this application simultaneously achieves three major functions—three-dimensional force measurement, internal wire channel retention, and active-passive physical isolation—within a limiting outer diameter of 1.5 mm.

[0028] Workflow: This application achieves real-time three-dimensional force sensing of the SCS electrode tip 3 by integrating FBG sensing fiber 6 into the electrode tip 3. This effectively compensates for the severe signal distortion when the operator relies on tactile sensation between the operating ends to judge the tip status, fundamentally reducing the risk of iatrogenic injuries such as dural puncture and nerve root damage. At the same time, the FBG sensing fiber 6 itself is thin and inherently resistant to electromagnetic interference, fundamentally solving the problem that traditional electrical sensors cannot be co-integrated with active stimulation electrodes and are susceptible to interference from electrical stimulation pulses. In addition, using an elastic sleeve 1 as the mounting base for the FBG sensing fiber 6 avoids the viscoelastic hysteresis and creep problems caused by directly pasting the FBG sensing fiber 6 onto the surface of the flexible electrode, ensuring the repeatability and response speed of force measurement. Furthermore, the elastic deformation unit overcomes the technical obstacle of extremely low axial force resolution caused by the large axial stiffness of thin-walled tubular electrodes by reducing the local axial stiffness of the elastic sleeve. The elastic sleeve 1 maintains the structural stability of the sensing segment, avoiding radial buckling deformation when the flexible electrode is subjected to axial force, further improving the accuracy of three-dimensional force decoupling.

[0029] In some embodiments, each elastic deformation unit 4 includes a plurality of deformation holes 41, which are arranged at intervals along the axial direction of the elastic sleeve 1. The deformable hole 41 has two end circular hole sections 411 respectively located at its two ends, and an intermediate transition section 412 located between the two end circular hole sections 411; both end circular hole sections 411 are circular holes of equal diameter; the axial height of the intermediate transition section 412 along the elastic sleeve 1 gradually decreases from its middle part to both sides, and the two ends of the intermediate transition section 412 are smoothly connected to the end circular hole sections 411 on the corresponding sides.

[0030] Specifically, such as Figure 4As shown, the end circular hole section 411 has a fixed diameter, ensuring that the deformable hole 41 maintains a constant cross-sectional size at both ends, guaranteeing stable mechanical properties in this region and avoiding stress concentration. The intermediate transition section 412 is located between the two end circular hole sections 411. Its axial height along the elastic sleeve 1 gradually decreases from the middle to both sides, with the axial height being the largest in the middle region and gradually narrowing towards both ends, eventually smoothly connecting with the diameter of the end circular hole section 411. The two ends of the intermediate transition section 412 are connected to the end circular hole section 411 by a smooth curve transition, avoiding the stress concentration problem caused by right angle or sharp corner connections, which is beneficial to improving the fatigue life and mechanical response linearity of the elastic deformation unit 4.

[0031] When the elastic sleeve 1 is subjected to axial force, the axial stiffness of the thin-walled region between adjacent deformation holes 41 within the same elastic deformation unit 4 is lower than that of other parts of the sleeve. Therefore, the axial force preferentially induces elastic deformation in this thin-walled region, resulting in localized strain concentration. The deformation holes 41 within each elastic deformation unit 4 are arranged at axial intervals, causing the elastic sleeve 1 to form multiple axially distributed thin-walled deformation regions within the elastic deformation unit 4 region. These multiple thin-walled deformation regions together constitute an axially concentrated strain region. The FBG grid region 61 is located within the elastic deformation region and can sense its overall axial strain, thereby converting minute axial displacements into axial strain that can be effectively detected by the FBG, achieving passive physical enhancement of axial force measurement. Simultaneously, the end circular hole section 411 maintains the structural strength at both ends of the deformation hole 41, ensuring that the deformation hole 41 can recover its original shape after repeated stress, guaranteeing the repeatability and long-term stability of the sensor.

[0032] In some embodiments, the elastic deformation units 4 are arranged symmetrically in pairs, and the deformation holes 41 of two adjacent elastic deformation units 4 are staggered. The deformation holes 41 of the two symmetrically arranged elastic deformation units 4 are arranged in a one-to-one correspondence to prevent radial buckling of the elastic sleeve 1 when it is compressed.

[0033] Specifically, such as Figure 4 As shown, multiple elastic deformation units 4 are arranged circumferentially along the outer wall of the elastic sleeve 1. Adjacent elastic deformation units 4 are not aligned in the axial direction, but are staggered by a certain distance. That is, the deformation holes 41 of adjacent elastic deformation units 4 are alternately staggered in the axial direction. At the same time, the deformation holes 41 contained in two elastic deformation units 4 arranged symmetrically in the circumferential direction correspond one-to-one in the axial direction.

[0034] Through the aforementioned staggered arrangement, the deformation holes 41 of adjacent elastic deformation units 4 are staggered axially, avoiding the formation of continuous stiffness weakening bands at the same axial position of the elastic sleeve 1 by each elastic deformation unit 4. This makes the stiffness distribution of the elastic sleeve 1 more uniform in all circumferential positions, thereby preventing radial buckling of the elastic sleeve 1 under axial pressure and ensuring the structural stability of the elastic sleeve 1 and the uniformity of strain distribution of the FBG sensing fiber 6. At the same time, since the deformation holes 41 of the two symmetrically arranged elastic deformation units 4 correspond one-to-one, it ensures that the FBG sensing fiber 6 at the symmetrical position can generate a completely symmetrical strain response when subjected to radial force. This provides a structural basis for subsequently using the difference in wavelength drift of the FBG sensing fiber 6 at the symmetrical position to cancel out the temperature term and the axial force term, thereby accurately decoupling the radial force (such as the first radial force and the second radial force).

[0035] In some embodiments, each FBG sensing fiber 6 is fixedly connected to the receiving groove 5, and the FBG grid region 61 of each FBG sensing fiber 6 is movably disposed within the corresponding elastic deformation region.

[0036] Specifically, such as Figure 1 and Figure 2 As shown, the FBG sensing fiber 6 is disposed within the receiving groove 5, and its FBG grating region 61 is located within the elastic deformation unit 4. The non-grating region of the FBG sensing fiber 6 is fixedly connected to the inner wall of the receiving groove 5 by multiple UV adhesives 7, so that the FBG sensing fiber 6 is reliably fixed within the receiving groove 5. At the same time, the FBG grating region 61 is in a non-fixed state within the elastic deformation region, that is, the FBG grating region 61 is not glued to the elastic deformation region, allowing for relative sliding or micro-gap fit. During the assembly process, an equal initial tensile preload is applied to each FBG sensing fiber 6, with a preload strain of approximately several hundred micro-strains.

[0037] Through the above encapsulation method, the FBG gate region 61 experiences pure and uniform axial linear tensile and compressive strain when subjected to force, effectively avoiding local stress concentration and spectral chirp problems caused by the fiber being bonded to the trench wall. At the same time, the deformation recovery of the pure metallic elastomer is rapid, and combined with the initial tensile preload, it can overcome the stress relaxation of the adhesive layer under long-term use, greatly reducing the hysteresis and time delay of the sensor. In addition, the initial tensile preload allows the fiber to safely and accurately measure the axial compressive force by reducing the tension, avoiding the fiber from buckling and breaking due to axial micro-bending, thus improving the reliability and fatigue life of the sensing unit.

[0038] In some embodiments, the elastic sleeve 1 is connected to the electrode tip 3 by an insulating member 2, which is used to isolate the elastic sleeve 1 from the active stimulation wire inside the electrode.

[0039] Specifically, the spinal cord stimulation electrode body is a flexible tubular electrode made of medical polyurethane material, which contains multiple active stimulation leads.

[0040] Specifically, the insulating component 2 is a ZrO2 insulating pin made of zirconium dioxide ceramic material, which combines high insulation and high mechanical strength. This insulating component 2 passes through both the elastic sleeve 1 and the electrode, and is fixedly connected to both the elastic sleeve 1 and the electrode using medical adhesive. This connection method electrically isolates the metal sleeve from the active stimulation wire inside the electrode, preventing the metal sleeve from becoming energized and causing leakage when electrical stimulation pulses are applied, thus ensuring electrical safety in clinical use.

[0041] In some embodiments, four FBG sensing fibers 6 are provided, and the four FBG sensing fibers 6 are equally spaced along the outer wall of the elastic sleeve 1.

[0042] Specifically, such as Figure 7 As shown, four FBG sensing fibers 6 are evenly arranged at 90-degree intervals along the outer circumference of the elastic sleeve 1, meaning the four FBG sensing fibers 6 are orthogonally symmetrically arranged around the sleeve. This arrangement ensures that when the elastic sleeve 1 is subjected to radial force, the two FBG sensing fibers 6 positioned opposite each other produce strain responses of equal magnitude but opposite signs, thus facilitating accurate decoupling of the radial force through differential signal processing. Simultaneously, the orthogonal symmetrical arrangement of the four FBG sensing fibers 6 also provides a structural basis for temperature compensation in subsequent signal processing.

[0043] Example 2 Please refer to Figure 8 This application provides a safe delivery method based on a fiber optic force sensor, which is implemented using the fiber optic force sensor integrated into the spinal cord electrical stimulation electrode provided in Example 1. The fiber optic force sensor is connected to a fiber optic demodulator, which is connected to a control device. The fiber optic demodulator collects the wavelength drift signal of each FBG sensing fiber 6 in real time and converts the wavelength drift signal into a wavelength drift amount and outputs it to the control device.

[0044] The method includes the following steps: S100: During the delivery of spinal cord electrical stimulation electrodes, the real-time wavelength drift of each FBG sensing fiber is acquired in real time using an optical fiber demodulator. The real-time wavelength drift is then used to form a column vector, and the column vector is multiplied by the decoupling matrix to obtain the three-dimensional contact force and ambient temperature change values. The three-dimensional contact force includes at least the axial force. The decoupling matrix is ​​obtained by inverting the calibration sensitivity matrix, which is established based on the linear combination relationship between the wavelength drift of each FBG sensing fiber and the three-dimensional contact force and ambient temperature change values. Specifically, during delivery, the fiber optic demodulator continuously emits probe light into the FBG sensing fiber 6 and receives the reflected light signal. When the electrode tip 3 is subjected to a three-dimensional contact force, the elastic sleeve 1 deforms, and the FBG grating region 61 senses this deformation and outputs a sensing signal in the form of the reflected center wavelength drift. The fiber optic demodulator converts the optical signal into a digital signal and collects the reflected center wavelength drift of each FBG sensing fiber 6 in real time, recording it as the real-time wavelength drift. , , , .

[0045] In this embodiment, four real-time wavelength drift values ​​are used. ~ Construct column vectors Then, perform matrix multiplication between the column vectors and the decoupling matrix C, that is:

[0046] The first radial force at the current moment can be calculated simultaneously. Second radial force Axial force and ambient temperature change value .

[0047] The decoupling matrix C is obtained by inverting the calibration sensitivity matrix; the specific calibration method is described in subsequent steps. During real-time measurement, simply substitute the four real-time wavelength drift values ​​acquired into the matrix multiplication formula above; no repeated calibration or complex strain decomposition calculations are required. In this embodiment, the sampling frequency of the fiber optic demodulator is no less than 100Hz, meaning it outputs a set of wavelength drift data every 10ms. Correspondingly, the control device calculates and outputs the three-dimensional contact force and temperature change values ​​in real time at the same frequency to meet the real-time requirements of dynamic response to force signals during electrode delivery.

[0048] Furthermore, methods for obtaining the decoupling matrix include: S1: Apply known static loads in the first, second, and third directions to the fiber optic force sensor respectively, and collect the reflection center wavelength drift of the four FBG sensing fibers 6 at different ambient temperatures; the first, second, and third directions are perpendicular to each other; Specifically, known static loads are applied to the sensor along a first direction (X direction), a second direction (Y direction), and a third direction (Z direction), respectively. The first direction, the second direction, and the third direction are perpendicular to each other and correspond to the first radial force in three-dimensional space. Second radial force and axial force .

[0049] The wavelength shift of the reflection center of the four FBG sensing fibers 6 under known loads in each direction was collected using an optical fiber demodulator and recorded as the calibration wavelength shift. , , , Six sets of load-unload cycle experiments were conducted in each direction. Twenty data points were collected from each set, and the average value was taken to improve the reliability of the calibration data. During the calibration process, data could also be collected at different ambient temperatures to incorporate ambient temperature variation values. As the fourth dimension.

[0050] S2: Using the known static load force value and ambient temperature change value as independent variables, and the four wavelength drift values ​​as dependent variables, the sensitivity coefficients of the first direction, the second direction, the third direction, and the temperature sensitivity coefficient are obtained by least squares fitting, and a calibration sensitivity matrix is ​​established. Specifically, the amount of calibration wavelength shift collected will be... , , , As the dependent variable, the known applied static load force value ( , , ) and ambient temperature change value Using as the independent variable, establish a linear fitting model.

[0051] Before establishing the fitting model, the wavelength drift principle of FBG sensing fiber 6 will be explained first. The reflection center wavelength of FBG sensing fiber 6... The effective refractive index of the grating and modulation period Decide:

[0052] When the FBG sensing fiber 6 is subjected to total strain Or changes in ambient temperature At that time, the wavelength of its reflection center shifts, and the amount of wavelength shift is... satisfy: ;in: The optical strain coefficient of the optical fiber. This represents the grating temperature sensitivity coefficient. The formula indicates that the wavelength shift incorporates both strain and temperature information.

[0053] Under three-dimensional force, the total strain of a single FBG is the superposition of axial strain and bending strain: ;in, For the first radial bending strain, For the second radial bending strain, For axial strain.

[0054] Under axial force, the equivalent axial stiffness of the elastic deformation zone is: ;in: The axial stiffness of a single FBG; The equivalent axial stiffness of the elastic deformation zone in the elastic sleeve 1, excluding the optical fiber; the four FBG sensing optical fibers 6 generate axial strains of the same magnitude, and the axial strain of a single FBG is:

[0055] in:; is the axial length of the elastic deformation zone. This represents the overall deformation of the elastic deformation zone; Under the action of the first radial force, the entire fiber optic force sensor is equivalent to a cantilever beam. FBG1 and FBG3 are located in the plane of the X direction (first direction) and are a distance r from the neutral axis, generating first radial bending strains of equal magnitude but opposite sign: ;in, The first radial bending strain of FBG1, The first radial bending strain of FBG3. R is the distance from the application point to the FBG grid region 61; r is the distance from the FBG to the neutral axis; E is the elastic modulus of the elastic sleeve 1; I is the moment of inertia of the section; L1 is the axial length of the elastic deformation zone.

[0056] FBG2 and FBG4 are located on the neutral axis, and their bending strain is zero, i.e.: Among them, among them, The first radial bending strain of FBG2, The first radial bending strain of FBG4 is given.

[0057] Similarly, under the action of the second radial force, FBG2 and FBG4 generate second radial bending strains of equal magnitude but opposite sign, while FBG1 and FBG3 have zero bending strains at the neutral axis position.

[0058] Based on the strain superposition principle described above, combining the basic FBG principle formula with the strain decomposition formula, we can obtain the wavelength shifts of the four FBG sensing fibers 6 respectively with... , , and A system of linear equations with four unknowns.

[0059] Because the four FBGs are orthogonally and symmetrically arranged at 90° intervals along the circumference of the outer wall of the sleeve, the sensitivity coefficients of two FBGs (FBG1 and FBG3, FBG2 and FBG4) located in opposite positions to the same radial force are equal in magnitude but opposite in sign. This utilizes the conjugate characteristic of the symmetrical arrangement ( , , , By subtracting the wavelength shifts of the two pairs of symmetrically arranged FBG sensing fibers 6, the temperature and axial force terms can be canceled out, thereby decoupling the first and second radial forces.

[0060]

[0061] in, This represents the wavelength shift of FBG1. This represents the wavelength shift of FBG2. This represents the wavelength shift of FBG3. This represents the wavelength shift of FBG4.

[0062] By summing and averaging the wavelength shifts of the two pairs of symmetrically arranged FBG sensing fibers 6, the bending strain term can be canceled out, resulting in two equations containing two unknowns: axial force and temperature change.

[0063]

[0064] The aforementioned symmetrical cancellation relationship of subtraction / summation and averaging constitutes the wavelength shift of the four FBG sensing fibers 6. ~ and , , and The system of linear equations between the four equations ensures that the four equations are linearly independent and that the system of equations has a unique solution.

[0065] Based on the above physical principles and mathematical relationships, a linear fitting model is established: ; in, i =1,2,3,4 represent four FBG sensing optical fibers 6 respectively; The wavelength shift measured by the i-th FBG sensing fiber 6 during the calibration phase (corresponding to when i=1) (and so on). , , , These are 6 pairs of sensing fibers for the i-th FBG. , , and The sensitivity coefficient.

[0066] Substituting the calibration data collected in step S101 into the above fitting model and fitting it using the least squares method, the sensitivity coefficients of each physical quantity for each FBG sensing fiber 6 can be determined. ~ Taking the first FBG sensing fiber 6 as an example, when different known force values ​​are applied in the X direction, a set of ( , The sensitivity coefficient for that direction can be obtained by linear fitting of the data points using the least squares method. Similarly, by applying a known force value in the Y direction, we can obtain the result. And so on. Ultimately, a total of 16 sensitivity coefficients can be determined from the four FBG sensing fibers.

[0067] Arranging the above 16 sensitivity coefficients into a 4×4 matrix yields the calibration sensitivity matrix K:

[0068] in, and These are the initial reflection center wavelengths of two pairs of FBGs (FBG1 / FBG3 and FBG2 / FBG4) arranged symmetrically. The optical strain coefficient of the optical fiber; R is the distance from the application point to the FBG grid region 61; r is the distance from the FBG to the neutral axis; E is the elastic modulus of the elastic sleeve 1; I is the moment of inertia of the section; L1 is the axial length of the elastic deformation zone. The axial stiffness of a single FBG; This is the equivalent axial stiffness of the elastic deformation zone in the elastic sleeve 1, excluding the optical fiber. and These are the temperature sensitivity coefficients for two symmetrically arranged pairs of FBGs (FBG1 / FBG3 and FBG2 / FBG4). Each row in the matrix corresponds to the wavelength shift equation of one FBG sensing fiber 6, and each column corresponds to... , , and Sensitivity coefficients for four unknowns.

[0069] The symmetric cancellation relationship between the rows of the above matrix (e.g.) , ; , ; This ensures that the K matrix is ​​a non-singular matrix and has invertibility.

[0070] S3: Invert the calibration sensitivity matrix to obtain the decoupling matrix.

[0071] Specifically, the Moore-Penrose generalized inverse matrix is ​​obtained by calculating the established calibration sensitivity matrix K, thus yielding the decoupling matrix C: .

[0072] S200: If the axial force is determined to be greater than or equal to the overload warning threshold, an overload warning signal is issued and the recursion speed is adjusted.

[0073] Specifically, the calculated axial force is compared with a preset overload warning threshold. Compare the overload warning thresholds. It is predetermined through simulated tissue contact experiments and is used to distinguish between normal tissue contact and abnormal collision overload. In this embodiment, the overload warning threshold is 5N.

[0074] The control device determines whether the axial force is greater than or equal to the overload warning threshold: if If it is, it is determined to be an abnormal collision overload event, and an overload warning is issued; if If the condition is not met, monitoring will continue without triggering an alert.

[0075] Specifically, when the axial force is determined to be greater than or equal to the overload warning threshold, the control device immediately triggers an overload warning. The overload warning signal is output in parallel through the following two methods: First, the device provides warning information to the operator through sound and light. The control device drives the buzzer to sound an alarm, and at the same time displays an "overload warning" message and the current axial force value on the display, reminding the operator that an abnormal collision has occurred at electrode tip 3 and that the push should be stopped immediately.

[0076] Second, for automated delivery systems, the control device directly transmits an overload warning signal to the system's control unit, triggering an emergency stop command or a push speed adjustment command. Upon receiving this signal, the automated delivery system immediately performs a deceleration or stops the push operation, thus achieving physical safety protection and preventing tissue damage caused by operator delays or misjudgments.

[0077] After the overload warning signal is triggered, the control device continues to monitor the axial force in real time. When the axial force falls below the overload warning threshold, the warning signal is automatically deactivated, and the automated delivery system can resume normal delivery or be manually resumed by the surgeon upon confirmation.

[0078] Furthermore, it also includes the following steps: S300: If the axial force is determined to be less than the overload warning threshold, then determine whether the axial force is greater than or equal to the contact threshold; wherein the contact threshold is less than the overload warning threshold. Specifically, the control device compares the axial force calculated in step S100 with a preset overload warning threshold. If the axial force is determined to be less than the overload warning threshold (indicating that it is within the safe operating range), it further determines whether the axial force is greater than or equal to the contact threshold; wherein, the contact threshold is less than the overload warning threshold. In this embodiment, the contact threshold is predetermined through a simulated tissue contact experiment and is used to determine whether the axial force has reached the force level required for tissue contact. In this embodiment, the contact threshold is 1N; if the axial force is less than the contact threshold (less than 1N), it indicates that the electrode tip has not contacted the tissue, and the system maintains the monitoring state without issuing any prompts.

[0079] S400: If so, calculate the load change rate based on the axial force and determine whether the load change rate is greater than the impact threshold. Specifically, if the axial force is greater than or equal to the contact threshold, it indicates that the electrode tip has physically adhered to the tissue. At this point, the load change rate is calculated based on the time-series axial force data, and it is determined whether the load change rate is greater than the impact threshold. In this embodiment, the impact threshold is predetermined through simulated tissue contact experiments to determine whether the force change is sufficiently drastic to eliminate interference from slow friction. In this embodiment, the impact threshold is 15 N / s.

[0080] In this embodiment, the load change rate is calculated using the sliding window numerical differentiation method. Let the current sampling time be... ,forward Each sampling point time is ,in Width of the sliding window (in the number of sampling points). Given the sampling period, the formula for calculating the load change rate is:

[0081] in, The axial force at the current moment, For the front Axial force at each sampling point. Sliding window width. Five sampling points are taken, corresponding to a 50ms time window; sampling period The sampling time is 10ms (i.e., the sampling frequency is 100Hz). By using a sliding window for numerical differentiation, the interference of high-frequency noise on the calculation of the load change rate can be effectively filtered out, while ensuring a fast response to force changes.

[0082] The control device continuously calculates the load change rate at the same sampling frequency (not less than 100Hz) as the fiber optic demodulator, thereby enabling real-time monitoring of the 3-axis force state at the electrode tip.

[0083] S500: If the load change rate is greater than the impact threshold, it is determined to be a tip obstruction event and an obstruction warning signal is issued. Specifically, if the load change rate exceeds the impact threshold (greater than 15 N / s), it indicates a dramatic increase in axial force within a very short time (tens of milliseconds). This physical phenomenon corresponds to the electrode tip suddenly encountering tissue during rapid advancement, i.e., a "tip obstruction event." At this point, the control device identifies it as a tip obstruction event and issues an obstruction warning signal. This signal is relayed to the operator via audio-visual means, driving a flashing indicator light (such as a yellow indicator light) or displaying the message "Tip obstructed" on the monitor. This is a high-intensity warning, prompting the operator to transition from the rapid advancement phase to the delicate operation phase.

[0084] S600: If the load change rate is less than or equal to the impact threshold, it is determined to be a tip contact state and a contact state warning signal is issued.

[0085] Specifically, if the load change rate is less than or equal to the impact threshold (less than or equal to 15 N / s), it indicates that although the force has reached the contact level (e.g., in the 1N~5N range), the force increase is smooth and slow. This physical phenomenon corresponds to the electrode tip being in contact with the tissue, in a state of slow pushing or friction, without instantaneous impact. At this time, the control device determines that the tip is in contact and issues a contact status indication signal. This status indication signal is a low-intensity indication (e.g., only driving the yellow indicator light to remain constantly lit, without emitting a sound), only providing the operator with the status of "currently in contact with tissue," and does not trigger automatic deceleration or stopping. The specific operation is determined by the operator based on clinical experience.

[0086] It should be noted that the contact identification steps S300 to S600 and the overload warning step S200 together constitute a graded safety system. The difference between contact identification and overload warning is as follows: Contact identification focuses on the difference between "the instant of collision" and "gradual contact" (distinguished by impact threshold). It is triggered when the axial force reaches the contact threshold and the load change rate is too large, providing the operator with an emergency notification of momentary obstruction. This is an informative prompt and does not interfere with the delivery operation. On the other hand, the overload warning is triggered when the axial force reaches the overload warning threshold (a higher threshold). The system automatically decelerates or stops pushing, which is a mandatory safety protection.

[0087] The interval (1N-5N) between the contact threshold and the overload warning threshold provides the operator with a safe operating window. If the operator's reaction is delayed and the axial force continues to rise to the overload warning threshold, the system automatically intervenes to decelerate or stop. This design not only perfectly avoids misjudgment of slow friction caused by only looking at the force value, but also avoids misjudgment of slight disturbances caused by only looking at the rate of change. By first checking whether the force value has been reached (whether there is contact), and then checking whether the rate of change is large (whether there is a collision), it achieves the goal of accurately distinguishing between transient actions and steady-state states, thereby forming an effective balance between operator decision-making and system protection.

[0088] Furthermore, it also includes the following steps: The deflection angle and azimuth angle of the electrode tip are calculated based on the three-dimensional contact force, so that the operator can adjust the pushing direction; Based on the three-dimensional contact force output in real time in step S200 (the three-dimensional contact force specifically includes the first radial force, the second radial force, and the axial force), calculate the deflection angle of the electrode tip 3. and azimuth .

[0089] skew angle Used to characterize the degree of tilt of the electrode as a whole away from the axial direction. When the electrode is pushed straight along the axial direction, the radial net force is zero, and the tilt angle is... When the electrode is laterally deflected, the radial resultant force increases, and the deflection angle increases. Increase accordingly. Deflection angle The calculation formula is:

[0090] Azimuth Azimuth angle is used to characterize the orientation of an electrode within a cross-section perpendicular to the axial direction (XY plane), and to determine the specific direction in which the electrode deflects. The calculation formula is:

[0091] in, This is the arctangent function for the four quadrants, returning a value in radians, with a range of values ​​of 1000. Azimuth The specific meaning is: This indicates that the electrode is biased towards the positive X direction (e.g., on the right side). This indicates a bias towards the positive Y direction (such as the front side). This indicates a bias towards the negative Y direction (such as the rear side). or This indicates a bias towards the negative X direction (e.g., left side). The surgeon determines this based on the azimuth angle. This allows us to determine the specific direction of the electrode's deflection within the cross-section.

[0092] Specifically, the control device will calculate the deflection angle. and azimuth The information is displayed to the surgeon in a visual manner. In this embodiment, the deflection angle and azimuth angle are displayed numerically on the monitor. Simultaneously, the direction and degree of electrode deflection within the cross-section are visually shown on the monitor as two-dimensional arrows or vector graphics. The direction of the arrow corresponds to the azimuth angle, and the length of the arrow corresponds to the magnitude of the deflection angle. By observing the display interface, the surgeon can obtain real-time attitude information of the electrode tip 3: the deflection angle tells the surgeon "how much the electrode has deflected," and the azimuth angle tells the surgeon "in which direction the electrode has deflected."

[0093] Based on the output skew angle and azimuth angle, the surgeon can determine the current skew state of the electrode and adjust the pushing direction accordingly. For example, when the azimuth angle shows that the electrode tip is skewed to the right, the surgeon should adjust the pushing direction to the left to bring the electrode back to the center position; when the skew angle is large, the surgeon should reduce the pushing force and adjust the direction slowly to avoid the electrode colliding violently with the cavity wall tissue due to excessive skew.

[0094] It should be noted that the three-dimensional contact force data output in step S100 is the common data basis for all functional modules of this application. Among them, the overload warning is based on a comparison between the magnitude of the axial force and a preset overload warning threshold, and is an event-triggered mandatory protection function; contact identification (including tip obstruction events and tip contact states) is based on a comprehensive judgment of the magnitude of the axial force and the load change rate of the axial force, and is an event-triggered feedback prompt function. The pose prompt continuously calculates and outputs the deflection angle and azimuth angle of the electrode tip based on the three-dimensional contact force (including axial force, first radial force, and second radial force), and is a navigation function that operates throughout the entire process. The pose prompt is continuously output throughout the delivery process, and its output result is not affected by whether contact identification or overload warning is triggered.

[0095] The above description is merely a preferred embodiment of this application and an explanation of the technical principles employed. Those skilled in the art should understand that the scope of the invention involved in this application is not limited to technical solutions formed by specific combinations of the above-described technical features, but should also cover other technical solutions formed by arbitrary combinations of the above-described technical features or their equivalents without departing from the inventive concept. For example, technical solutions formed by substituting the above features with (but not limited to) technical features with similar functions disclosed in this application.

Claims

1. An optical fiber force sensor integrated with a spinal cord electrical stimulation electrode, characterized by, include: An elastic sleeve (1) is disposed on one side of the electrode tip (3), and the elastic sleeve (1) is connected to the electrode tip (3). An elastic deformation zone is provided on the elastic sleeve (1). The elastic deformation zone has multiple elastic deformation units (4). The multiple elastic deformation units (4) are provided on the elastic sleeve (1) and are spaced apart along the outer wall of the elastic sleeve (1). The elastic deformation units (4) are used to reduce the axial stiffness of the elastic sleeve (1). The receiving groove (5) is provided in multiple ways, and each receiving groove (5) is provided on the outer wall of the electrode and extends along its axial direction to the elastic sleeve (1). FBG sensing fiber (6), multiple FBG sensing fibers (6) are provided, and each FBG sensing fiber (6) has an FBG grid area (61); the FBG sensing fibers (6) are respectively disposed in the corresponding receiving groove (5), and the FBG grid area (61) is located in the elastic deformation zone, for sensing the deformation of the elastic deformation zone.

2. The fiber optic force sensor integrated into a spinal cord electrical stimulation electrode according to claim 1, characterized in that, Each of the elastic deformation units (4) includes a plurality of deformation holes (41), which are arranged at intervals along the axial direction of the elastic sleeve (1); The deformable hole (41) has two end circular hole sections (411) respectively located at its two ends, and an intermediate gradient section (412) located between the two end circular hole sections (411); the two end circular hole sections (411) are circular holes of equal diameter; the axial height of the intermediate gradient section (412) along the elastic sleeve (1) gradually decreases from its middle part to both sides, and the two ends of the intermediate gradient section (412) are smoothly connected to the end circular hole sections (411) on the corresponding sides.

3. The fiber optic force sensor integrated into a spinal cord electrical stimulation electrode according to claim 2, characterized in that, The elastic deformation units (4) are arranged symmetrically in pairs. The deformation holes (41) of two adjacent elastic deformation units (4) are staggered, and the deformation holes (41) of the two symmetrically arranged elastic deformation units (4) are arranged one-to-one to prevent the elastic sleeve (1) from buckling radially when it is compressed.

4. The fiber optic force sensor integrated into a spinal cord electrical stimulation electrode according to claim 1, characterized in that, Each of the FBG sensing optical fibers (6) is fixedly connected to the receiving groove (5), and the FBG grid region (61) of each of the FBG sensing optical fibers (6) is movably disposed within the corresponding elastic deformation region.

5. The fiber optic force sensor integrated into a spinal cord electrical stimulation electrode according to claim 1, characterized in that, The elastic sleeve (1) is connected to the electrode tip (3) by an insulating member (2), which is used to isolate the elastic sleeve (1) from the active stimulation wire inside the electrode.

6. The fiber optic force sensor integrated into a spinal cord electrical stimulation electrode according to claim 1, characterized in that, Four FBG sensing optical fibers (6) are provided, and the four FBG sensing optical fibers (6) are equally spaced along the outer wall of the elastic sleeve (1).

7. A secure delivery method based on a fiber optic force sensor, implemented using the fiber optic force sensor integrated into the spinal cord electrical stimulation electrode as described in any one of claims 1-6, wherein the fiber optic force sensor is connected to a fiber optic demodulator, and the fiber optic demodulator is connected to a control device, characterized in that... Includes the following steps: During the delivery of spinal cord electrical stimulation electrodes, the real-time wavelength drift of each FBG sensing fiber is acquired in real time using an optical fiber demodulator. The real-time wavelength drift is then used to construct a column vector, and the column vector is multiplied by a decoupling matrix to obtain the three-dimensional contact force and ambient temperature change values. The three-dimensional contact force includes at least axial force. The decoupling matrix is ​​obtained by inverting a calibration sensitivity matrix, which is established based on the linear combination relationship between the wavelength drift of each FBG sensing fiber and the three-dimensional contact force and ambient temperature change values. If the axial force is determined to be greater than or equal to the overload warning threshold, an overload warning signal is issued and the recursion speed is adjusted.

8. A secure delivery method based on an optical fiber force sensor according to claim 7, characterized in that, The method further includes: Known static loads in a first direction, a second direction, and a third direction are applied to the fiber optic force sensor, respectively, and the wavelength shift of the reflection center of the four FBG sensing fibers is collected at different ambient temperatures; the first direction, the second direction, and the third direction are perpendicular to each other; Using the known static load force value and ambient temperature change value as independent variables, and the four wavelength drift values ​​as dependent variables, the sensitivity coefficients of the first direction, the second direction, and the third direction, as well as the temperature sensitivity coefficient, are obtained by least squares fitting, and a calibration sensitivity matrix is ​​established. The decoupling matrix is ​​obtained by inverting the calibration sensitivity matrix.

9. A secure delivery method based on an optical fiber force sensor according to claim 7, characterized in that, It also includes the following steps: If it is determined that the axial force is less than the overload warning threshold, then it is determined whether the axial force is greater than or equal to the contact threshold; wherein the contact threshold is less than the overload warning threshold. If so, calculate the load change rate based on the axial force and determine whether the load change rate is greater than the impact threshold. If the load change rate is greater than the impact threshold, it is determined to be a tip obstruction event, and an obstruction warning signal is issued. If the load change rate is less than or equal to the impact threshold, it is determined to be a tip contact state, and a contact state warning signal is issued.

10. A secure delivery method based on an optical fiber force sensor according to claim 7, characterized in that, It also includes the following steps: The deflection angle and azimuth angle of the electrode tip are calculated based on the three-dimensional contact force, so that the operator can adjust the pushing direction.

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