Intracranial peripheral heart multifunctional pacing guide wire based on optical fiber sensing

Abstract

The invention discloses an intracranial peripheral heart multifunctional pacing guide wire based on optical fiber sensing, and relates to the field of medical instruments, and the pacing guide wire comprises a near-end interface section, a middle sensing section and a far-end sensing section which are sequentially connected from the near end to the far end; the middle sensing section comprises a layered coaxial structure, and the layered coaxial structure comprises a core layer, a sensing waveguide layer wrapping the core layer, a conductive layer wrapping the sensing waveguide layer and a lubricating layer wrapping the conductive layer from inside to outside; a polymer waveguide extending in the axial direction of the guide wire is arranged in the sensing waveguide layer, and the track of the polymer waveguide is a three-dimensional spiral line. The three-dimensional spiral polymer waveguide is integrated in the sensing waveguide layer, the intuition and reliability of navigation can be remarkably improved, information guarantee is provided for the pacing electrode to accurately reach and stably abut against the heart target spot, and therefore the success rate and safety of an operation are improved.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to a guidewire for transvascular interventional surgery, specifically a multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing. Background Technology

[0002] Interventional vascular surgery is an important direction in modern medicine. Procedures such as pacemaker implantation require the precise delivery of electrode leads to specific locations on the heart via the venous system. During the procedure, surgeons rely on imaging techniques such as X-ray fluoroscopy for navigation. However, two-dimensional images cannot provide crucial mechanical information such as the interaction forces between the guidewire and the vessel wall, or the three-dimensional shape of the guidewire. This leads to difficulties in guidewire advancement in complex anatomical structures, such as intracranial vessels or peripheral coronary arteries, posing risks of perforation and spasm. Furthermore, the final electrode placement and stability are difficult to assess in real time. Therefore, developing intelligent guidewires that can provide real-time mechanical and shape feedback is of great significance for improving surgical safety, precision, and success rates.

[0003] To endow guidewires with sensing capabilities, existing technologies attempt to integrate fiber optic sensors within the guidewire. A common approach is to embed ordinary quartz fiber gratings within the guidewire sheath. Fiber gratings can convert physical quantities such as strain and temperature into changes in light wavelength; by demodulating these changes, the bending shape and contact force of the guidewire can be sensed. This technological approach aims to address the blind spots in traditional surgery where surgeons rely solely on touch and imaging.

[0004] However, existing sensing guidewires based on embedded fiber Bragg gratings exhibit several inherent defects when dealing with real-world clinical environments, especially in tortuous blood vessels that require repeated and rapid bending. First, when the guidewire body undergoes a small-radius bend, the internal fiber is subjected to tension on the outer side and compression on the inner side, easily leading to macro-bending loss, causing optical signal attenuation or even interruption, resulting in insufficient reliability. Second, non-uniform bending or compression can cause chirping distortion in the reflection spectrum of the fiber Bragg grating, broadening or splitting the reflection peak, rendering conventional demodulation algorithms ineffective and severely reducing measurement accuracy. Furthermore, the physical interface between the fiber and the encapsulation sheath material generates micro-friction during dynamic bending, leading to hysteresis and nonlinearity in strain transmission. This means the sensing signal lags behind the actual deformation of the guidewire, and the relationship is not constant, failing to achieve true real-time mechanical feedback. This affects the precise arrival of the electrode at the pacing target, delaying treatment effectiveness.

[0005] Therefore, it is necessary to improve the existing pacing guidewires to solve the above problems. Summary of the Invention

[0006] This invention overcomes the shortcomings of existing technologies and provides a multifunctional intracranial and peripheral cardiac pacing guidewire based on fiber optic sensing. It abandons the traditional approach of embedding pre-fabricated optical fibers within the sheath and instead uses femtosecond laser direct writing technology to fabricate a polymer waveguide with a specific three-dimensional helical trajectory inside the functional layer material of the guidewire. The polymer fiber grating is then directly inscribed onto this waveguide, avoiding sharp bends in the sensing optical path and ensuring the stability and spectral quality of the optical signal transmission. By optimizing the helical parameters, the influence of the sensing structure on the overall stiffness of the guidewire is reduced to an extremely low level, thereby retaining the excellent handling feel of traditional guidewires.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention provides a multifunctional intracranial and peripheral cardiac pacing guidewire based on fiber optic sensing, comprising a proximal interface segment, an intermediate sensing segment, and a distal sensing segment connected sequentially from the proximal end to the distal end.

[0008] The intermediate sensing segment includes a layered coaxial structure, which, from the inside out, includes a core layer, a sensing waveguide layer covering the core layer, a conductive layer covering the sensing waveguide layer, and a lubricating layer covering the conductive layer.

[0009] The sensing waveguide layer contains a polymer waveguide extending along the axial direction of the guide wire. The polymer waveguide is a refractive index modulation channel formed by direct writing within the sensing waveguide layer material using a femtosecond laser. The trajectory of the polymer waveguide is a three-dimensional helix.

[0010] At least one polymer fiber Bragg grating is etched on the polymer waveguide; a pacing electrode is integrated at the distal end of the distal sensing segment, and the pacing electrode is electrically connected to the conductive layer.

[0011] In a preferred embodiment of the present invention, the three-dimensional helical trajectory of the polymer waveguide is such that the local radius of curvature at any point on the trajectory is greater than or equal to a preset curvature safety threshold.

[0012] In a preferred embodiment of the present invention, the preset curvature safety threshold is ≤2 mm.

[0013] In a preferred embodiment of the present invention, the helical diameter of the three-dimensional helical trajectory of the polymer waveguide is smaller than the thickness of the sensing waveguide layer.

[0014] In a preferred embodiment of the present invention, the three-dimensional helical trajectory of the polymer waveguide is located in the mechanically neutral layer region of the intermediate sensing segment when it is bent.

[0015] In a preferred embodiment of the present invention, a plurality of polymer fiber Bragg gratings with different center wavelengths are etched at intervals along the axial direction of the polymer waveguide.

[0016] In a preferred embodiment of the present invention, the proximal interface segment is provided with an optical interface for connecting to an external demodulator and an electrical interface for connecting to an external pacemaker. The optical interface is optically connected to the polymer waveguide, and the electrical interface is electrically connected to the conductive layer.

[0017] In a preferred embodiment of the present invention, the pacing electrode is a ring-shaped or hemispherical electrode.

[0018] In a preferred embodiment of the present invention, the material of the sensing waveguide layer is polyimide or cyclic olefin copolymer.

[0019] In a preferred embodiment of the present invention, the core layer is a nickel-titanium alloy superelastic wire, and the conductive layer is a metal braided mesh or a spiral wound wire.

[0020] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0021] (1) This invention provides a multifunctional intracranial and peripheral cardiac pacing guidewire based on fiber optic sensing. It integrates a three-dimensional helical polymer waveguide into the sensing waveguide layer and extends it along the guidewire axis. The polymer fiber Bragg gratings inscribed therein can sense the strain experienced by the guidewire when it is pushed in the blood vessel. By demodulating and analyzing multiple grating signals, the three-dimensional bending shape and spatial position of the guidewire in the tortuous blood vessel can be reconstructed in real time, thereby realizing the accurate prediction and guidance of the movement trajectory of the guidewire tip. This can significantly improve the intuitiveness and reliability of navigation, and provide information guarantee for the pacing electrode to accurately reach and stably attach to the cardiac target point, thereby improving the success rate and safety of the operation.

[0022] (2) In this invention, the polymer waveguide is not an external or embedded independent optical fiber. It is a refractive index modulation channel directly written into the polymer matrix material such as polyimide by femtosecond laser. There is no separation interface. When the guide wire body undergoes bending deformation, the strain can be continuously and directly transmitted from the matrix material to the waveguide structure, thereby avoiding signal transmission loss caused by relative slippage and friction between different materials. Compared with the traditional method of embedding or encapsulating quartz optical fiber in a sheath, the structure of this invention can eliminate the hysteresis phenomenon and nonlinearity of strain transmission, thereby ensuring the authenticity and accuracy of mechanical feedback and providing reliable sensing support for surgical operations.

[0023] (3) The polymer waveguide in this invention has a three-dimensional helical trajectory with constant curvature, which can ensure that when the optical signal is transmitted in the waveguide, even if the guide wire is bent sharply, the actual bending path experienced by the light wave is always gentle, which can effectively suppress the macro-bending loss of light. At the same time, the waveguide structure can be located at or near its mechanical neutral layer when the guide wire is bent, and its contribution to the overall bending stiffness of the guide wire tends to be minimal. Compared with the addition of conventional optical fiber in the guide wire, which leads to a stiffer feel and a decrease in torsional transmission performance, this invention can effectively retain the original flexibility and excellent pushing and torsional feel of the guide wire, so as to maintain signal stability in tortuous blood vessels. The doctor's feel is not affected by the sensor during operation, which improves the surgical controllability.

[0024] (4) In this invention, multiple polymer fiber Bragg gratings with different center wavelengths are inscribed to form a quasi-distributed sensing network in series. This network can not only measure bending morphology, but also simultaneously sense multiple physical parameters such as axial stress and temperature through specific design. This enables multi-functional integration within a single process platform and material system. Furthermore, it provides measurement accuracy and reliability for simultaneously monitoring key physiological and mechanical parameters such as the contact force between the electrode and myocardial tissue and the local temperature at the pacing guidewire tip, providing more dimensions of monitoring data for surgery and supporting the needs of complex surgical scenarios. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic cross-sectional view of the pacing guidewire according to a preferred embodiment of the present invention;

[0027] Figure 2 This is a schematic cross-sectional view of the intermediate sensing segment of a preferred embodiment of the present invention;

[0028] Figure 3 This is a schematic diagram of the perspective structure of the sensing waveguide layer according to a preferred embodiment of the present invention;

[0029] In the figure: 1. Proximal interface segment; 2. Intermediate sensing segment; 3. Distal sensing segment; 31. Pacing electrode; 4. Core layer; 5. Sensing waveguide layer; 51. Polymer waveguide; 511. Polymer fiber Bragg grating; 6. Conductive layer; 7. Lubricating layer. Detailed Implementation

[0030] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0031] Many specific details are set forth in the following description in order to provide a full understanding of the invention. However, the invention may also be practiced in other ways different from those described herein. Therefore, the scope of protection of the invention is not limited to the specific embodiments disclosed below.

[0032] In the description of this application, it should be understood that "proximal" refers to the end closer to the doctor's operating handle, and "distal" refers to the end that extends into the patient's blood vessel and ultimately reaches the cardiac target. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0033] In the description of this application, it should be noted that, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections through an intermediate medium; and they can refer to the internal communication between two components. Those skilled in the art will understand the specific meaning of the above terms in this application based on the specific circumstances.

[0034] like Figure 1-3 As shown, a multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing includes a proximal interface segment 1, an intermediate sensing segment 2, and a distal sensing segment 3 connected sequentially from proximal to distal. The intermediate sensing segment 2 includes a layered coaxial structure, which, from the inside out, includes a core layer 4, a sensing waveguide layer 5 covering the core layer 4, a conductive layer 6 covering the sensing waveguide layer 5, and a lubricating layer 7 covering the conductive layer 6. A polymer waveguide 51 extending along the guidewire axis is disposed within the sensing waveguide layer 5. The polymer waveguide 51 is a refractive index modulation channel formed by direct writing within the material of the sensing waveguide layer 5 using a femtosecond laser, and the trajectory of the polymer waveguide 51 is a three-dimensional helix. At least one polymer fiber Bragg grating 511 is etched on the polymer waveguide 51. A pacing electrode 31 is integrated at the distal end of the distal sensing segment 3, and the pacing electrode 31 is electrically connected to the conductive layer 6.

[0035] It should be noted that this pacing guidewire is a polymer sheathed guidewire. The elastic modulus of its polymer sheath is lower than that of metal materials, which allows it to better conform to the vessel wall in tortuous blood vessels (such as the aorta, intracranial vessels, coronary arteries, etc.), improving tracking and passability.

[0036] Specifically, this invention's pacing guidewire abandons the traditional sensing method of embedding pre-fabricated silica optical fibers within the guidewire sheath. Instead, it uses femtosecond laser direct writing technology to grow an embedded optical waveguide with a specific three-dimensional helical trajectory within the guidewire's own polymer functional layer, and directly inscribes a polymer fiber Bragg grating 511 (PFBG) onto this waveguide. The basic principle is that the specific geometric parameters of the three-dimensional helix ensure that the waveguide itself never bends sharply in space, thus avoiding macro-bending loss and spectral chirping of the optical signal when the guidewire bends sharply. Simultaneously, since the waveguide and sensing waveguide layer 5 are integrally formed without a physical interface, strain transfer is continuous and slip-free, effectively eliminating the hysteresis and nonlinearity problems found in traditional encapsulated fiber solutions. Furthermore, by optimizing the helical parameters, the waveguide structure can be located at or near the mechanically neutral layer when the guidewire bends, and its contribution to the overall bending stiffness of the guidewire approaches zero. Therefore, while integrating high-precision sensing functions, it also retains the excellent pushability, torsion resistance, and smooth feel of traditional guidewires.

[0037] The following will describe in detail, with reference to the accompanying drawings and multiple embodiments, the specific implementation of the above core concept, the structure of each component, the connection relationship, the manufacturing process, and their collaborative working process.

[0038] Example 1:

[0039] This embodiment provides a multifunctional intracranial and peripheral cardiac pacing guidewire based on fiber optic sensing. The guidewire is slender and cylindrical, and its total length can be designed according to clinical needs. For example, when used for transvenous pacemaker implantation, the length is typically 145-150 cm. (Refer to...) Figure 1 As shown, the guidewire is divided into three functional segments from the proximal end where the doctor operates, i.e. the hand-held end, to the distal end that enters the blood vessel, i.e. the tip end: proximal interface segment 1, intermediate sensing segment 2, and distal sensing segment 3.

[0040] In this embodiment, the proximal interface segment 1 serves as a hub for connecting the guidewire to external devices. Its structure is relatively thick and rigid to facilitate gripping and connection by the physician. The proximal interface segment 1 is equipped with an optical interface and an electrical interface. The optical interface connects the polymer waveguide 51 inside the guidewire to the fiber optic patch cord of an external demodulator (e.g., SM125 or SI155 static fiber optic grating demodulator) via a transition fiber. The electrical interface is a standard medical electrical connector, such as IS-1 or DF-1 type, used to connect the conductive layer 6 inside the guidewire to the electrical circuit of an external pacing pulse generator.

[0041] In this embodiment, the intermediate sensing segment 2 is the main body of the guidewire, as shown in the reference. Figure 2 As shown, its structure, from the inside out, includes a core layer 4, a sensing waveguide layer 5 covering the core layer 4, a conductive layer 6 covering the sensing waveguide layer 5, and a lubricating layer 7 covering the conductive layer 6. The core layer 4 provides basic support, pushing resistance, and shape memory resilience for the guidewire. It uses a Nitinol wire with superelastic properties, preferably a NiTi alloy superelastic wire produced by Fort Wayne Metals, with a diameter range of 0.2-0.5 mm. This material can almost completely recover its original shape after undergoing large strain bending, making it very suitable for repeated deformation in tortuous blood vessels.

[0042] Furthermore, the sensing waveguide layer 5, covering the core layer 4, requires materials with excellent biocompatibility, transparency, elasticity, and good sensitivity to laser modification. In this embodiment, polyimide (PI) is preferably used, which is uniformly coated or extruded onto the core layer 4 and cured to form an insulating layer with a thickness of approximately 80-150 μm. This polyimide serves as the substrate material for the subsequent femtosecond laser direct writing to form the waveguide.

[0043] Furthermore, a conductive layer 6 covers the sensing waveguide layer 5, serving as a pathway for the pacing current and providing electromagnetic shielding for the internal sensing system to reduce external electromagnetic interference. The conductive layer 6 employs a metal braided mesh or a tightly wound helical wire structure, preferably using 16 strands of MP35N alloy wire woven into a tubular mesh at a 45° braiding angle, covering the outer surface of the sensing waveguide layer 5, with a thickness of 20-50 μm.

[0044] Furthermore, the outermost layer is a lubricating layer 7, used to reduce the coefficient of friction between the guidewire and the blood vessel wall, improving the guidewire's passage within the blood vessel. The lubricating layer 7 is a hydrophilic coating, preferably a polyvinylpyrrolidone (PVP) coating. A uniform, smooth hydrophilic film with a thickness of 5-15 μm is formed on the surface of the conductive layer 6 through dip coating or spraying processes. When the guidewire enters the blood environment, this coating rapidly hydrates, forming a surface with extremely low friction.

[0045] In this embodiment, the distal sensing segment 3 is the tip of the guidewire, used to perform pacing stimulation and provide fine local sensing. Its structure is a continuation of the intermediate sensing segment 2. The core layer 4 transitions tapered at the distal sensing segment 3, meaning the diameter of the nickel-titanium alloy wire gradually decreases to increase the flexibility of the tip and avoid puncturing myocardial tissue. At the distal end of the distal sensing segment 3, a pacing electrode 31 is integrated. The pacing electrode 31 is preferably a ring electrode or a hemispherical electrode, such as a ring electrode made of platinum-iridium alloy with a width of 0.5-2 mm, which is electrically connected to the conductive layer 6 extending thereto by laser welding or conductive adhesive bonding. The pacing electrode 31 needs to ensure sufficient contact area with myocardial tissue to reduce pacing impedance, while its edges are smooth to avoid tissue damage. Near or below the pacing electrode 31, a polymer waveguide 51 extends thereto, and PFBG is inscribed at its end for high-sensitivity monitoring of the contact force between the electrode and myocardial tissue and local temperature.

[0046] It is understood that the polymer waveguide 51 of the present invention is not a pre-fabricated independent optical fiber embedded in the sensing waveguide layer 5, but rather a refractive index modulation channel drawn in situ inside the polyimide matrix material using femtosecond laser direct writing technology. Its trajectory is a three-dimensional spatial helix embedded in the polymer layer, which extends along the axial direction of the guide wire.

[0047] Specifically, refer to Figure 3 As shown, the helix diameter of the three-dimensional helical trajectory is slightly smaller than the thickness of the sensing waveguide layer 5. This ensures that the waveguide is completely embedded within the polymer material and not exposed on the surface, thus maintaining the smoothness and integrity of the guide wire surface. For example, the sensing waveguide layer 5 has a thickness of 100 μm and a helix diameter of 60-80 μm. The helix pitch determines the spatial density of sensing points along the guide wire axis and is set according to the navigation accuracy requirements. If one sensing point (corresponding to one PFBG) is desired every 5 mm, the pitch can be set to 5 mm. A smaller pitch provides higher spatial resolution but increases the path length and complexity of laser processing and may also introduce more optical transmission loss. The direction of the helix, i.e., left-handed or right-handed, can be in the same direction or opposite to the guide wire axis. Its selection needs to be coordinated with the orientation of the grating plane subsequently inscribed by the PFBG to optimize the strain sensing direction.

[0048] The pacing guidewire of this invention features a constant or minimum curvature design for the three-dimensional helical trajectory. In three-dimensional computer modeling, algorithm optimization ensures that the local radius of curvature at any point on this helical trajectory is greater than or equal to a preset safety threshold. This safety threshold is set based on the macro-bending loss characteristics of the optical waveguide and is much larger than the critical bending radius of traditional silica optical fiber. In this embodiment, the preset curvature safety threshold is preferably ≤2 mm. Therefore, regardless of the sharp bend the guidewire body is bent in the blood vessel, since the polymer waveguide 51 itself moves in a gentle helical motion within the polymer matrix, the local bending at any point on its optical transmission path remains gentle, thus geometrically avoiding macro-bending loss caused by sharp bends.

[0049] Furthermore, the three-dimensional helical trajectory of the polymer waveguide 51 is located in the mechanically neutral layer region of the intermediate sensing segment 2 during bending. The mechanically neutral layer refers to the layer within a beam or rod that neither elongates nor shortens during pure bending deformation. For the composite layered guidewire in this invention, the position of the neutral layer depends on the elastic modulus and thickness of each layer. Through finite element analysis, the position of the neutral layer in the guidewire cross-section under typical bending loads can be determined. Then, the helical diameter of the helical waveguide and its radial position within the sensing waveguide layer 5 are adjusted to make its path coincide as closely as possible with the calculated neutral layer. When the waveguide is located at or near the neutral layer, the axial strain (tension or compression) experienced by the waveguide itself during guidewire bending will be very small, and its contribution to the overall bending stiffness of the guidewire will also be minimized, achieving stress concealment or zero stiffness contribution. This makes the guidewire with integrated sensing system exhibit almost identical pushing force, torsional transmission performance, and overall feel to traditional guidewires without sensors. Doctors cannot feel the presence of internal sensors during operation, thus preserving the crucial tactile feedback.

[0050] In this embodiment, the sensing element is a polymer fiber Bragg grating 511 (PFBG) directly inscribed onto a three-dimensional helical polymer waveguide 51. Using the same or similar femtosecond laser processing system, laser parameters are adjusted at predetermined positions on the helical waveguide, such as corresponding points for each pitch, to inscribe periodic refractive index modulation inside the waveguide, forming a PFBG. Multiple PFBGs with different center wavelengths can be inscribed at certain intervals along the waveguide axis.

[0051] For example, the center wavelength spacing of each PFBG is 2-5 nm, which together form a quasi-distributed sensing network in series. The writing direction of the PFBG, that is, the direction of the grating vector, can be consistent with the local tangent direction of the helical waveguide. Thus, when the guide wire bends, the PFBG mainly senses the strain along the waveguide axis, and the signal response is the most regular and sensitive.

[0052] The following describes in detail how the above structures work together to achieve their functions and effects:

[0053] At the start of the procedure, the surgeon holds the handle of the proximal interface segment 1 of the guidewire and percutaneously inserts the distal end of the guidewire into the blood vessel. Broadband light emitted from the external demodulator is coupled into the polymer waveguide 51 inside the guidewire through the optical interface. The light propagates in the helical waveguide, passing through each PFBG in sequence. Each PFBG reflects back a narrowband light signal with a specific center wavelength, while the remaining light continues to propagate forward.

[0054] As the guidewire is advanced and bends within the blood vessel, strain is generated in the guidewire body. Because the polymer waveguide 51 and the polyimide matrix are integrally molded at the molecular level without a physical interface, the strain is continuously and seamlessly transmitted from the guidewire body to the helical waveguide and the PFBG inscribed thereon. Upon axial strain, the reflected center wavelength of the PFBG shifts. These wavelength shifts are detected in real time by an external demodulator. Due to the hysteresis-free and linear strain transmission, the detected wavelength change corresponds highly linearly to the actual bending curvature of the guidewire at that location.

[0055] More importantly, due to the constant curvature design of the three-dimensional helical waveguide, no matter how severe the overall bending of the guide wire, the actual path curvature experienced by the optical signal during transmission within the waveguide remains gentle. Therefore, the intensity of the optical signal remains highly stable throughout the entire transmission process, with minimal fluctuations. Simultaneously, each PFBG is in a relatively uniform strain field throughout the bending process, maintaining a narrow and symmetrical reflection spectrum without chirping broadening or splitting, thus ensuring high precision and reliability of wavelength demodulation.

[0056] The demodulator transmits wavelength data from multiple PFBGs to a computer. Using pre-calibrated strain-curvature relationships and the known spatial positions of the PFBGs (determined by the geometric model of the helical trajectory), shape reconstruction algorithms, such as the Frenet-Serret framework, piecewise constant curvature method, or strain integral-based methods, can calculate the continuous bending shape of the guidewire centerline in three-dimensional space in real time. Based on the two-dimensional images from X-ray fluoroscopy, the doctor can simultaneously view a real-time three-dimensional morphological reconstruction of the guidewire on a display screen, allowing them to intuitively understand the guidewire's specific path in the tortuous blood vessel, its relative position to the vessel wall, and whether it has formed a loop, thus achieving real-time visual navigation throughout the entire process.

[0057] When the distal sensing segment 3 of the guidewire approaches or reaches the cardiac pacing target, the pacing electrode 31 integrated at the tip comes into contact with the myocardial tissue. At this time, the PFBG near the tip can sensitively detect the micro-strain caused by the contact, thereby calculating the contact force between the electrode and the tissue. Simultaneously, the PFBG is also sensitive to temperature, monitoring the local myocardial temperature. This information is fed back to the physician in real time to determine whether the electrode is stably attached and ideally positioned, assisting the physician in adjusting the guidewire to ensure that the pacing electrode 31 is released and fixed in the optimal position. During the process, due to the waveguide's neutral layer design, the guidewire maintains excellent flexibility and maneuverability, allowing the physician to perform precise pushing and rotating operations as with ordinary guidewires, unaffected by the built-in sensing system.

[0058] Example 2:

[0059] Based on Example 1, this embodiment further focuses on the detailed geometric design of the three-dimensional helical trajectory of the polymer waveguide 51, and quantitatively verifies its signal stability and the impact on feel under extremely small bending radii through design comparison experiments, so as to fully disclose and prove the advantages of the present invention.

[0060] Sample A is a traditional embedded quartz fiber guidewire; Sample B is the pacing guidewire of this invention.

[0061] Preparation of Sample A: The same layered coaxial structure as in Example 1 was used as the base, namely a nickel-titanium alloy core wire with a diameter of 0.36 mm, a polyimide insulating layer with a thickness of 100 μm, a metal braided conductive layer 6, and a PVP lubricating layer 7. The difference was that, after coating the polyimide layer but before curing, a single-mode silica fiber with a core diameter of 9 μm, a cladding diameter of 125 μm, and a coating diameter of 250 μm (Corning fiber SMF-28e+) was embedded and fixed in a straight line onto the surface of the uncured polyimide layer, and then cured as a whole. Four FBGs with a center wavelength spacing of 3 nm were pre-written on the fiber, with a grating spacing of 5 cm. After curing, the fiber was encapsulated within the polyimide layer.

[0062] Preparation of Sample B: The structure is the pacing wire from Example 1, with a 100 μm thick polyimide layer coated on the same nickel-titanium core wire. A three-dimensional helical waveguide was fabricated inside the wire using a femtosecond laser direct writing system, specifically a FemtoFiber pro series femtosecond laser from LightFab, with a center wavelength of 515 nm, a pulse width <300 fs, and a repetition frequency of 1 MHz. The specific helical parameters are designed as follows: helical diameter of 70 μm and pitch of 5 mm. A trajectory optimization algorithm was used to ensure that the local radius of curvature at any point on the helical line was ≥ 2 mm. Four PFBGs were inscribed at 5 mm intervals (one at each pitch point), with a center wavelength interval of 3 nm. The radial position of the waveguide trajectory on the cross-section was optimized using finite element simulation, placing it near the neutral layer calculated when the wire was bent (radius 5 mm) (approximately 0.12 mm from the central axis). Subsequently, a metal braided mesh and PVP coating were applied to complete the fabrication of Sample B.

[0063] Furthermore, the stability and spectral quality of the optical signal under dynamic bending, as well as the feel of the guide wire, were tested, mainly focusing on the performance of bending stiffness.

[0064] Experiment 1: Test of optical power stability and spectral distortion under different radii of curvature.

[0065] S1. Connect the near-end optical interfaces of sample A and sample B to the broadband light source and the spectrometer, respectively.

[0066] S2. Fix the middle section of the guidewire sample (approximately 10 cm long, including all FBG / PFBG sensor points) onto a fixture that allows precise control of the bending radius. The fixture consists of two movable clamping blocks; by adjusting the distance between the clamping blocks, the guidewire section can be bent into semicircles of different radii.

[0067] S3. Starting with a bending radius of 20 mm, gradually decrease the bending radius, setting it successively to 10 mm, 5 mm, 3 mm, 2 mm, and 1.5 mm. At each bending radius, maintain the bending state for 10 seconds.

[0068] S4. In each state, use a spectrometer to record: (a) the peak power of the signal light reflected back from the farthest FBG / PFBG to assess transmission loss; and (b) the reflection spectrum of one of the intermediate FBG / PFBGs to observe the peak shape changes.

[0069] S5. Restore the bending radius to a straight state (consider it as an infinite radius), and record the light power and spectrum in the straight state as a reference.

[0070] The test results are shown in Table 1.

[0071] Table 1:

[0072]

[0073] As shown in Table 1, experimental data indicate that under extreme conditions of sharp bending (R≤2 mm), sample A, i.e., the traditional embedded quartz fiber guidewire, suffers severe signal attenuation or even interruption due to macro-bending loss and uneven strain, resulting in severe spectral distortion and unreliable operation. In contrast, sample B, i.e., the pacing guidewire of this invention, benefits from a constant curvature trajectory design, exhibiting minimal optical power fluctuation (<0.5 dB) and stable spectral morphology. This demonstrates its superior resistance to bending interference and signal reliability, fully meeting the requirements for operation in the most tortuous blood vessels, such as intracranial and coronary arteries.

[0074] Experiment 2: Bending stiffness test.

[0075] S1. Use a universal testing machine equipped with a three-point bending fixture.

[0076] S2. Place the middle sensing section (length L=30 mm) of sample A and sample B horizontally on two support rollers with a spacing of 20 mm between the support rollers.

[0077] S3. Above the midpoint of the guidewire, apply downward pressure with a loading head at a speed of 1 mm / min until a deflection of 1 mm is produced.

[0078] S4. Record the load-displacement curve during the loading process.

[0079] S5. Calculate the equivalent bending stiffness of the guide wire sample based on the elastic beam theory.

[0080] The test results are shown in Table 2.

[0081] Table 2:

[0082]

[0083] As shown in Table 2, Sample A exhibits a significantly increased stiffness due to the embedding of a thicker quartz optical fiber. Through the comparative experiments described above, Sample B, i.e., the pacing guidewire of this invention, demonstrates a significantly reduced negative impact of the sensing system on the overall stiffness of the guidewire through its geometric layout, thereby achieving a balance between high-performance sensing and excellent handling feel.

[0084] Example 3:

[0085] Based on Examples 1-2, this embodiment further discloses the femtosecond laser direct writing manufacturing process and specific parameters of the three-dimensional helical polymer waveguide 51 and PFBG.

[0086] The manufacturing process includes the following steps:

[0087] S1. Provide a NiTi wire with a diameter of 0.36 mm. Use a dip-coating process to uniformly coat a layer of polyimide prepolymer solution on the surface of the core wire: use PI-2611 polyimide precursor solution from HD MicroSystems, and coat at a speed of 50 r / min to make the wet film dry and cured to a thickness of 100 μm. Put the coated core wire into an oven and keep it at 80 ℃ for 30 min to remove most of the solvent. Then, increase the temperature to 150 ℃ at 2 ℃ / min and keep it for 1 h. Then, increase the temperature to 250 ℃ at 1 ℃ / min and keep it for 2 h. Finally, let it cool naturally to room temperature to form a polyimide insulating layer on the surface of the core wire.

[0088] S2. Fix the guide wire substrate prepared in S1 onto a five-axis motion platform. The laser processing system uses a femtosecond laser with the following preferred parameters: center wavelength 515 nm, pulse width 250 fs, and repetition frequency adjustable from 100 to 5 MHz. The laser pulse energy is finely adjusted using a neutral density filter array. After beam expansion and collimation, the laser beam is incident on a high numerical aperture objective lens and focused at a predetermined depth within the polyimide layer.

[0089] It should be noted that the machining process is controlled by a computer numerical control system, which coordinates the switching / modulation of the five-axis platform and the laser according to a pre-programmed three-dimensional helical trajectory and the position program written by PFBG. The specific process is as follows:

[0090] a. A computer-controlled five-axis platform moves the laser focus within the polyimide layer according to a preset three-dimensional spiral equation. The laser emits light continuously at a high repetition rate and pulse energy. Nonlinear absorption occurs in the polyimide material within the tiny volume scanned by the laser focus, causing chemical bond rearrangement or density increase, resulting in a permanent, slight increase in the refractive index of that region. Numerous voxels connect to form an optical channel within the polyimide matrix with a refractive index slightly higher than the surrounding material, i.e., an embedded polymer waveguide 51. The scanning speed, i.e., the platform movement speed, is 1-10 mm / s.

[0091] b. When the platform moves to the preset PFBG marking position on the spiral trajectory, the platform pauses its axial movement. The control system lowers the laser's repetition frequency and increases the pulse energy. The laser performs a transverse line-by-line scan along a direction perpendicular to the waveguide axis, performing localized irradiation at this position. The controlled exposure generates periodic refractive index modulation in a localized region of the waveguide, forming a PFBG. The grating period Λ is determined according to the target center wavelength λ. B and the effective refractive index n of the waveguide eff From formula λ B =2n effThe Λ is determined. By controlling the exposure pattern, PFBGs with a length of approximately 1-3 mm can be written. After completing one PFBG, the platform continues to move to the next position and repeats the process to write the next PFBG with a different center wavelength.

[0092] S3. After completing the direct writing of all waveguides and PFBGs, a conductive layer 6 is formed on the outer surface of the sensing waveguide layer 5 by braiding 16 strands of MP35N alloy wire with a diameter of 0.025 mm into a tight tubular mesh at a 45° braiding angle. A layer of PVP hydrophilic coating solution is applied to the surface of the conductive layer 6 by dip coating and then dried and cured to form a lubricating layer 7. Finally, an optical interface connection is required at the proximal end of the guide wire. Due to the small diameter of the end face of the polymer waveguide 51, direct coupling efficiency with standard communication optical fiber is low. Therefore, tapered transition fiber or precision microlens coupling technology is required. A preferred method is to process a microlens structure at the end of the polyimide layer near the guide wire using a femtosecond laser, or to precisely align and permanently bond a section of thin-diameter optical fiber with an end face prepared as a spherical lens to the end face of the polymer waveguide 51 using a UV-curable adhesive with refractive index matching. The other end is connected to a standard optical fiber connector to form a complete optical interface.

[0093] The above description is based on the preferred embodiments of the present invention. It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of the invention is defined by the appended claims rather than the foregoing description, and all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

[0094] Furthermore, it should be understood that although this specification describes embodiments, not every embodiment contains only one independent technical solution. This narrative style is merely for clarity. Those skilled in the art should consider the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing, characterized in that, It includes a proximal interface segment, an intermediate sensing segment, and a remote sensing segment connected sequentially from the proximal end to the distal end; The intermediate sensing segment includes a layered coaxial structure, which, from the inside out, includes a core layer, a sensing waveguide layer covering the core layer, a conductive layer covering the sensing waveguide layer, and a lubricating layer covering the conductive layer. The sensing waveguide layer contains a polymer waveguide extending along the axial direction of the guide wire. The polymer waveguide is a refractive index modulation channel formed by direct writing within the sensing waveguide layer material using a femtosecond laser. The trajectory of the polymer waveguide is a three-dimensional helix. At least one polymer fiber Bragg grating is etched on the polymer waveguide; a pacing electrode is integrated at the distal end of the distal sensing segment, and the pacing electrode is electrically connected to the conductive layer.

2. The multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: The three-dimensional helical trajectory of the polymer waveguide is such that the local radius of curvature at any point on the trajectory is greater than or equal to a preset curvature safety threshold.

3. The multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 2, characterized in that: The preset curvature safety threshold is ≤2 mm.

4. The multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: The diameter of the three-dimensional helical trajectory of the polymer waveguide is smaller than the thickness of the sensing waveguide layer.

5. The multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: The three-dimensional helical trajectory of the polymer waveguide is located in the mechanically neutral layer region when the intermediate sensing segment is bent.

6. The multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: Multiple polymer fiber Bragg gratings with different center wavelengths are inscribed at intervals along the axial direction of the polymer waveguide.

7. The multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: The proximal interface segment is provided with an optical interface for connecting to an external demodulator and an electrical interface for connecting to an external pacemaker. The optical interface is optically connected to the polymer waveguide, and the electrical interface is electrically connected to the conductive layer.

8. The multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: The pacing electrode is a ring-shaped or hemispherical electrode.

9. A multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: The material of the sensing waveguide layer is polyimide or cyclic olefin copolymer.

10. A multifunctional intracranial and extracranial peripheral cardiac pacing guidewire based on fiber optic sensing according to claim 1, characterized in that: The core layer is a nickel-titanium alloy superelastic wire, and the conductive layer is a metal braided mesh or a spiral wound wire.

Images