Integrated optical fiber pressure sensing guide wire based on Archimedes ring structure

Abstract

The invention discloses an integrated optical fiber pressure sensing guide wire based on an Archimedes ring structure, and relates to the field of medical instruments.The pressure sensing guide wire comprises a near-end pushing section, a transition section and a head-end sensing section which are sequentially arranged from the near end to the far end, a core wire is arranged in the guide wire, and the pressure sensing guide wire further comprises an Archimedes spiral framework, a pressure sensor and a pressure sensor, the sensor is arranged on the head end sensing section; the optical fiber pressure sensor is used for sensing the fluid pressure at the position where the optical fiber pressure sensor is located; the composite probe is used for sensing a three-dimensional contact force vector when the head end of the guide wire is in contact with tissue; the Archimedes spiral skeleton is arranged on the sensing section of the head end of the guide wire, and the optical fiber pressure sensor is fixed in the middle section of the skeleton, so that the generation mechanism of adherent artifacts can be effectively eliminated, the accuracy and reliability of blood flow pressure measurement are improved, the calibration frequency in an operation is reduced, and the operation time is shortened.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, and in particular to an integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure. Background Technology

[0002] In endovascular diagnostic and therapeutic procedures such as percutaneous coronary intervention, real-time and accurate acquisition of intravascular hemodynamic parameters is crucial. For example, fractional flow reserve (FFR) measurement is the gold standard for assessing the functional significance of coronary artery stenosis, which relies on accurate measurement of pressures distal to and proximal to the stenotic lesion. The intracranial vascular environment is dynamic and complex; the periodic pulsation of the heart, the tortuous anatomy of intracranial vessels, and the pulsatile characteristics of blood flow all pose significant challenges to the measuring instruments placed within it.

[0003] Currently, most pressure guidewires used clinically integrate miniature pressure sensors at their tips, such as those based on fiber optic sensing technology. These sensors are typically exposed directly on the guidewire tip surface, functioning by sensing changes in fluid pressure at their location. To obtain accurate measurements, the operator needs to repeatedly adjust the guidewire position during the procedure, attempting to center the sensor within the blood vessel lumen and away from the vessel wall, followed by a zeroing calibration. Existing technologies primarily focus on sensor miniaturization and sensitivity enhancement, or integrating a single type of fiber optic sensor onto a coaxial structure.

[0004] However, due to the small diameter of the tip of existing guidewires, the pressure sensor at its tip is prone to adhering to the vessel wall during advancement or under the impact of blood flow. When the sensor comes into contact with the vessel wall, it is subjected to mechanical compression, generating a spurious signal with a pressure much higher than the actual blood flow pressure, known as a wall artifact. This leads to severe distortion of the pressure measurement value, forcing the surgeon to interrupt the procedure, repeatedly adjust the guidewire, and frequently perform zeroing calibration. This not only prolongs the operation time and increases the complexity of the procedure but may also affect the accuracy of diagnostic and treatment decisions. Secondly, the mechanical forces within the intracranial vascular environment are multifaceted. The guidewire tip may simultaneously experience axial pressure from blood flow, radial compression from the vessel wall, and shear forces generated by motion. Traditional single-point or coaxial single-layer fiber optic grating sensors struggle to decouple these spatially coherent but directional mechanical components, resulting in ambiguous feedback signals. The surgeon cannot accurately determine whether the guidewire tip is in an ideal free-floating state, is pressing against a vessel bifurcation, or is rubbing against the vessel sidewall, lacking the vector sensing capability of the interaction force between the guidewire tip and the tissue.

[0005] Therefore, it is necessary to improve the existing guidewire technology to address the aforementioned problems. Summary of the Invention

[0006] This invention overcomes the shortcomings of the prior art and provides an integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure. The centralized spatial positioning achieved through the Archimedes spiral skeleton, combined with the multidimensional mechanical navigation information provided by the composite probe, enables the guidewire of this invention to clearly distinguish whether the sensor is in an interference-free central position, as well as the specific mechanical state when the guidewire tip contacts the tissue, thereby achieving precise positioning and sensing in both spatial and mechanical dimensions.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows: Firstly, the present invention provides an integrated optical fiber pressure sensing guidewire based on an Archimedes ring structure, comprising a proximal push section, a transition section, and a head-end sensing section arranged sequentially from the proximal end to the distal end. A core wire is disposed inside the guidewire, the core wire passing through the proximal push section and the transition section, and further comprising:

[0008] An Archimedes spiral framework, disposed on the head-end sensing segment, is deployed upon release into the blood vessel to adaptively position at least a portion of the head-end sensing segment in the central region of the blood vessel through its symmetrical radial elastic support force.

[0009] A fiber optic pressure sensor, fixed in the middle section of the Archimedes spiral skeleton, is used to sense the fluid pressure at its location.

[0010] A composite probe, located at the farthest end of the guidewire, is used to sense the three-dimensional contact force vector when the tip of the guidewire comes into contact with the tissue.

[0011] The Archimedes spiral skeleton works in conjunction with the composite probe to provide spatial position and mechanical contact information of the guidewire tip within the blood vessel.

[0012] In a preferred embodiment of the present invention, the Archimedes spiral skeleton is made of a superelastic material, and its outer diameter in the free state is slightly larger than the expected diameter of the target blood vessel.

[0013] In a preferred embodiment of the present invention, the Archimedes spiral skeleton is a two-dimensional planar spiral structure formed by heat setting of nickel-titanium alloy wire, and its spiral plane is perpendicular to the axis of the guide wire.

[0014] In a preferred embodiment of the present invention, the Archimedes spiral skeleton is fixedly connected to the core material of the transition section through its inner end, and its outer end is a free end.

[0015] In a preferred embodiment of the present invention, the fiber optic pressure sensor is a fiber optic FP interferometer sensor, which is fixedly connected to the outer side of the middle loop of the Archimedes spiral skeleton by a biocompatible adhesive, and the plane of its pressure-sensing diaphragm is parallel to the spiral plane and faces the direction of blood flow.

[0016] In a preferred embodiment of the present invention, the composite probe includes a miniature cantilever beam formed at the end of a single-mode optical fiber, and at least three fiber grating sensors disposed on the circumference of the root of the miniature cantilever beam for calculating three-dimensional force vectors.

[0017] In a preferred embodiment of the present invention, the outer surface of the proximal pushing segment is provided with a hydrophilic coating.

[0018] In a preferred embodiment of the present invention, the main body of the head-end sensing segment is made of polymer material.

[0019] In a preferred embodiment of the present invention, a streamlined leader is provided at the free end of the outermost ring of the Archimedes spiral skeleton; the streamlined leader is made of polyurethane.

[0020] In a preferred embodiment of the present invention, the sensing fiber used to connect the optical fiber pressure sensor and the composite probe passes through a channel inside the head end sensing section, the transition section and the proximal push section, and finally exits from the proximal end of the guidewire.

[0021] This invention addresses the shortcomings of the prior art and has the following beneficial effects:

[0022] (1) This invention provides an integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure. By setting an Archimedes spiral skeleton at the sensing section of the guidewire tip and fixing the fiber optic pressure sensor in the middle section of the skeleton, the sensor is physically constrained and stabilized in the central region of the blood vessel lumen by utilizing the uniform and symmetrical radial elastic support force generated between the Archimedes spiral skeleton and the blood vessel wall. This ensures that the fiber optic pressure sensor remains isolated from the blood vessel wall during the measurement process, thereby eliminating direct contact between the sensor and the blood vessel wall. Compared with traditional guidewires, which cannot distinguish between whether the guidewire is attached to the wall and the mechanical state when it is attached, easily leading to measurement distortion and forcing the surgeon to repeatedly adjust the guidewire position and frequently perform zeroing calibration, this invention can effectively eliminate the mechanism of attachment artifacts, improve the accuracy and reliability of blood flow pressure measurement, thereby reducing the number of intraoperative calibrations and shortening the operation time.

[0023] (2) This invention integrates an Archimedes spiral skeleton and a composite probe into the sensing segment at the tip, enabling the sensor to achieve stable center positioning and multidimensional mechanical sensing at the tip on a fine guidewire. This allows the guidewire to have both spatial positioning and mechanical sensing capabilities without increasing the outer diameter or sacrificing pushability and flexibility. Compared with the bias in the prior art that cannot achieve center positioning and multidimensional force sensing simultaneously through structural means while maintaining a fine outer diameter, the guidewire of this invention can achieve spatial and mechanical dual-dimensional positioning, providing precise multidimensional mechanical navigation for endovascular interventional diagnosis and treatment, thereby greatly improving the accuracy and safety of diagnosis and treatment operations.

[0024] (3) In this invention, the coordinated output of the central positioning information provided by the Archimedes spiral skeleton and the three-dimensional contact force vector information provided by the composite probe enables the operator to simultaneously obtain the spatial position of the guidewire tip in the blood vessel and the specific mechanical state when the tip contacts the tissue during the operation. The fusion of spatial and mechanical dual-dimensional information allows the operator to clearly distinguish whether the guidewire tip is in a free-floating state, pressing against the bifurcation of the blood vessel, or rubbing or sliding against the sidewall of the blood vessel. Compared with the existing technology, which can only provide single-point pressure signals and is difficult to decouple multi-component mechanical information, this invention can provide multi-dimensional mechanical navigation information, thereby improving the ability to perceive the state of the guidewire tip and the precision of control during interventional diagnosis and treatment, effectively reducing the risk of vascular injury, and thus improving the precision and safety of interventional diagnosis and treatment operations.

[0025] (4) In this invention, the symmetrical radial support force of the Archimedes spiral skeleton enhances the overall stability of the head end sensing segment. While achieving sensor center positioning, it can also reduce the small vibrations at the head end caused by blood flow impact and heart pulsation, providing a stable mechanical environment for the fiber optic pressure sensor fixed on it, thereby improving the signal-to-noise ratio and signal stability of the fiber optic pressure sensor. Compared with the prior art where the pressure sensor directly bears the interference of blood flow impact and guide wire vibration, this invention achieves the effects of center positioning and shock absorption and flow stabilization through a single structure. Attached Figure Description

[0026] 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.

[0027] Figure 1 This is a front view schematic diagram of the pressure sensing guidewire structure according to a preferred embodiment of the present invention;

[0028] Figure 2 This is a side view of the pressure sensing guidewire structure according to a preferred embodiment of the present invention;

[0029] Figure 3 This is a schematic diagram of the connection between the composite probe and the head-end sensing section in a preferred embodiment of the present invention.

[0030] In the diagram: 1. Proximal push section; 2. Transition section; 3. Head end sensing section; 4. Core wire; 5. Archimedes spiral skeleton; 51. Fiber optic pressure sensor; 52. Streamlined leader head; 6. Composite probe; 61. Miniature cantilever beam; 62. Fiber grating sensor. Detailed Implementation

[0031] 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.

[0032] 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.

[0033] 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 blood vessels inside the patient's skull. Furthermore, in the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0034] 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.

[0035] Application Overview:

[0036] After in-depth research, the applicant discovered that when the sensor comes into contact with the blood vessel wall, it not only experiences mechanical compression that produces artifacts, but more importantly, the constraint of the blood vessel wall alters the local flow field around the sensor. This results in the sensor sensing a complex coupled signal of fluid pressure and wall constraint force, rather than pure blood flow pressure. This mechanical coupling phenomenon is something that existing technologies cannot fundamentally solve.

[0037] For a long time, the industry has struggled to simultaneously achieve stable central positioning of sensors and multidimensional biomechanical sensing through structural means, while maintaining the guidewire's fine outer diameter to ensure its passability and flexibility. Therefore, existing solutions generally employ a process of repeated intraoperative adjustments and frequent zeroing calibrations, which not only prolongs surgical time and increases operational complexity but may also lead to misdiagnosis based on distorted data. Although some researchers have attempted to improve positioning by adding balloons or mesh structures, this often comes at the cost of guidewire flexibility and outer diameter, making it difficult to apply in tortuous intracranial vessels. The challenge of maintaining minimally invasive performance, achieving central positioning, and decoupling biomechanical information has remained unresolved.

[0038] like Figure 1 and Figure 2 As shown, this invention provides an integrated fiber optic pressure sensing guidewire based on an Archimedean ring structure, comprising a proximal push section 1, a transition section 2, and a tip sensing section 3 arranged sequentially from proximal to distal. A core wire 4 is disposed inside the guidewire, passing through the proximal push section 1 and the transition section 2. The invention is characterized by further comprising: an Archimedean spiral skeleton 5, disposed on the tip sensing section 3, the Archimedean spiral skeleton 5 being deployed upon release into the blood vessel to adaptively position at least a portion of the tip sensing section 3 in the central region of the blood vessel through its symmetrical radial elastic support force; a fiber optic pressure sensor 51, fixed in the middle section of the Archimedean spiral skeleton 5, for sensing the fluid pressure at its location; and a composite probe 6, disposed at the distal end of the guidewire, for sensing the three-dimensional contact force vector when the guidewire tip contacts the tissue. The Archimedean spiral skeleton 5 and the composite probe 6 work together to provide spatial position information and mechanical contact state information of the guidewire tip within the blood vessel.

[0039] The core of this invention lies in integrating an adaptive, centered Archimedean spiral framework 5 with a composite probe 6 capable of decoupling three-dimensional contact force vectors into the tip sensing segment 3 of a guidewire. The basic principle is as follows: when the guidewire enters a blood vessel, such as an intracranial vessel, the Archimedean spiral framework 5 automatically expands or contracts, using its symmetrical radial elastic force to stably support the fiber optic pressure sensor 51 fixed to it at the center of the blood vessel lumen, thereby isolating direct contact interference from the vessel wall and obtaining a pure blood flow pressure signal. Simultaneously, the composite probe 6, located at the very tip of the guidewire, senses in real time the three-dimensional forces (axial, radial, and shear forces) generated when the guidewire tip contacts the vessel wall or myocardial tissue, and converts these forces into clear vector information through calculation. The synergy of these two components allows the operator to not only obtain accurate central blood flow pressure but also clearly determine the spatial position of the guidewire tip (whether it adheres to the vessel wall) and the specific mechanical state when it adheres, achieving precise positioning and navigation in both spatial and mechanical dimensions. This effectively solves the measurement distortion and operational misjudgment problems caused by wall artifacts and blurred mechanical signals in traditional pressure guidewires, thereby significantly improving the accuracy and safety of endovascular interventional diagnosis and treatment.

[0040] 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 and their collaborative working process.

[0041] Example 1:

[0042] This embodiment provides a basic and preferred implementation. The guidewire body of this invention follows the basic structure of conventional interventional guidewires to ensure its pushability, torsion control, and biocompatibility. The total length of the guidewire can be set according to clinical needs; for example, the length for coronary intervention is approximately 190 cm. (Refer to...) Figure 1 As shown, functionally, the guidewire is divided into a proximal push section 1 with a length of about 185 cm, a transition section 2 with a length of about 3-5 cm, and a head end sensing section 3 with a length of about 10-20 mm.

[0043] In this embodiment, the proximal push section 1 constitutes the main body of the guidewire, and its core is the core wire 4. The core wire 4 is made of a metal material with good pushing strength and torsional stiffness, preferably a nickel-titanium alloy, with a diameter ranging from 0.2 to 0.5 mm. The core wire 4 starts from the proximal handle of the guidewire and extends through the entire proximal push section 1 and transition section 2. In the proximal push section 1, the core wire 4 is wrapped with a polymer sheath layer. This sheath layer is preferably made of a material with good lubricity, preferably one of polytetrafluoroethylene, high-density polyethylene, or polyimide, for low pushing resistance. The outermost layer of the polymer sheath layer is coated with a hydrophilic coating, preferably a coating of polyvinylpyrrolidone (PVP) or polyacrylic acid (PAA). This coating becomes extremely smooth after contact with water or blood, which can significantly reduce the friction of the guidewire during its movement in the catheter and blood vessel.

[0044] It should be noted that the present invention provides a pressure-sensing guidewire, which is also suitable as a guidewire for electrophysiological mapping or cardiac pacing, and belongs to the polymer-sheathed guidewire structure. In pacing guidewire application scenarios, pacing electrode leads can also be integrated within the proximal push section 1, and their routing can run parallel to the sensing optical fiber, sharing a protection channel. This is an adaptive improvement to conventional technology.

[0045] Furthermore, transition segment 2 is located between proximal push segment 1 and head-end sensing segment 3 to achieve a smooth transition in mechanical properties. In this segment, the diameter of the core wire 4 is a gradually tapering cone; exemplarily, the diameter of the core wire 4 gradually transitions from 0.356 mm at the proximal push segment 1 to 0.1 mm at the connection point of the head-end sensing segment 3. This gradient design ensures that the strong proximal push force can be effectively transmitted to the head end, while giving the head end sufficient flexibility and adaptability to the tortuous anatomy of intracranial blood vessels. The outer sheath of transition segment 2 is made of a softer polymer, preferably polyurethane or silicone rubber, to further enhance its bending performance.

[0046] Furthermore, the main body of the head-end sensing segment 3 is made of a flexible polymer material with excellent biocompatibility. The elastic modulus of the polymer sheath is significantly lower than that of metal, allowing it to better conform to the tortuous path of large blood vessels such as the aorta and reduce irritation to the vessel walls. (Refer to...) Figure 2 As shown, its tip sensing segment 3 integrates an Archimedes spiral framework 5, which is compressed during delivery and automatically unfolds after entering the target blood vessel. Through uniform and symmetrical radial elastic interaction with the blood vessel wall, it passively achieves the centering of the sensor on the cross-section of the blood vessel. At the same time, in order to decouple the complex multidimensional mechanical information when the guidewire tip contacts the tissue, this invention integrates a composite probe 6 at the far end of the guidewire.

[0047] In the workflow: the operator pushes the guidewire through the guiding catheter to the vicinity of the target blood vessel; when the sensing segment 3 at the tip of the guidewire (containing the compressed helical skeleton) is pushed out of the guiding catheter, the helical skeleton quickly recovers its preset planar helical shape due to its superelastic memory effect; the blood vessel wall applies a radial constraint force to the outer coil of the helix, forcing the helix to contract symmetrically, thereby automatically adjusting and stabilizing the fiber optic pressure sensor 51 fixed on the helical skeleton in the central region of the blood vessel lumen; at this time, the pressure signal sensed by the sensor is the pure blood flow pressure undisturbed by the vessel wall. At the same time, regardless of whether the tip of the guidewire is in contact with the blood vessel wall, the composite probe 6 at the top continuously monitors its stress state; if the tip contacts the tissue, the composite probe 6 immediately senses and calculates the three-dimensional contact force vector, and this information, along with the blood flow pressure information at the center position, is synchronously fed back to the external system, providing the operator with comprehensive navigation.

[0048] Specifically, the Archimedes spiral skeleton 5 is made of nickel-titanium alloy wire with superelasticity and shape memory effect, preferably SE508 from Memry Corporation. Its phase transformation temperature Af is designed to be below human body temperature, ensuring that it is completely in the austenitic phase in vivo, exhibiting excellent superelasticity. The diameter of the spiral wire is preferably 0.05-0.1 mm to balance support and flexibility.

[0049] In this embodiment, the spiral skeleton is made into a two-dimensional planar Archimedean spiral structure through a heat-setting process. The specific process is as follows: a straight nickel-titanium alloy wire is tightly wound on a mold mandrel with an Archimedean spiral groove to ensure that the spacing between each turn is constant; then it is placed in a heat treatment furnace and kept at a temperature of 400-500 ℃ for 5-15 min, followed by quenching or controlled cooling; after heat treatment, the nickel-titanium wire will permanently remember this spiral shape.

[0050] It should be noted that while Archimedes' helix is ​​often used in the mechanical field to generate uniform radial force or achieve precise displacement, there is an inherent contradiction between the stiffness of the helix and the adaptability of the blood vessel wall when it is applied in blood vessels: if the helix is ​​too stiff, it may damage the vascular endothelium; if the helix is ​​too flexible, it cannot effectively stabilize the sensor in the center of the blood vessel, resulting in measurement deviation.

[0051] Specifically, the polar equation of the Archimedes spiral framework 5 is expressed as r = a + bθ, where r is the polar radius, θ is the polar angle, a is the initial radius, and b is the pitch coefficient. In this embodiment, the initial radius a and the pitch coefficient b are not universal constants.

[0052] Furthermore, the initial radius parameter 'a' corresponds to the radius of the innermost circle of the spiral, and its value is related to the physical dimensions and installation position of the fiber optic pressure sensor 51. Let the outer diameter of the fiber optic pressure sensor 51 be 'd'. s To ensure the sensor is securely fixed to the middle loop of the helix and does not interfere with the inner loop structure, the initial radius 'a' must satisfy the following: δ is the safety margin, which is 0.05-0.1 mm.

[0053] More importantly, the initial radius 'a' is related to the size of the undisturbed zone in the central region of the blood vessel, and the central region of the blood vessel has a radius of R. c The core flow region is where blood flow velocity distribution is relatively uniform and the effect of vessel wall effect is minimal. c With blood vessel radius R v The relationship can be approximated as: R c ≈0.6R v (Under laminar flow conditions). Therefore, to ensure the sensor remains within the core flow region, after the helical framework positions the sensor, the distance from the sensor center to the blood vessel center should be less than R. c .

[0054] Furthermore, the pitch coefficient *b* determines the spacing between the spiral coils, affecting the radial support stiffness of the spiral skeleton and its adaptability to changes in vessel diameter; let the diameter range of the target vessel be... The corresponding radius range is The outer diameter D of the Archimedes spiral skeleton 5 in its free state. free Slightly greater than D max This is used to ensure that it remains under pressure within the blood vessel, thereby generating radial support force. The number of helical turns N is taken as 2.5-4 turns, then the pitch coefficient b and the outermost radius r in the free state... max (=D) free The following relationship exists between / 2):

[0055] ,in .

[0056] Therefore, we can conclude that: .

[0057] In this embodiment, a vascular compliance coefficient is further introduced to correct the pitch coefficient b. During the cardiac cycle, blood vessels undergo periodic expansion and contraction, and the amplitude of their diameter change is related to the vascular elastic modulus. Let the maximum instantaneous strain (diameter change rate) of the blood vessel be... (Taking 0.03-0.06, i.e., 3%-6%), the dynamic range of blood vessel diameter is:

[0058] .

[0059] To enable the helical skeleton to adapt to dynamic changes, its radial support stiffness needs to be sufficiently soft to accommodate vasoconstriction, yet sufficiently rigid to maintain central positioning during vasodilation. This balance is achieved by optimizing the pitch coefficient b.

[0060] This embodiment proposes that the pitch coefficient b should satisfy the following relationship:

[0061] .

[0062] Where k is the stiffness adjustment coefficient, ranging from 0.8 to 1.2; α is the vascular compliance compensation factor, ranging from 0.5 to 1.5, selected according to the elastic characteristics of the target vessel. For vessels with high elasticity, such as the aorta, a larger value is used to give the spiral better expansion following ability; for vessels with low elasticity, such as atherosclerotic stenosis, a smaller value is used to enhance the positioning stability of the spiral.

[0063] Understandably, by correlating the pitch coefficient *b* with the range of vessel diameter and the compliance coefficient, the helical skeleton can generate appropriate radial support force in vessels of different diameters. This is sufficient to stabilize the sensor in the central region of the vessel without causing damage to the vessel intima due to excessive stiffness. Simultaneously, a vascular compliance coefficient is introduced. The pitch coefficient b is modified so that the helical skeleton can adaptively adjust to follow the periodic expansion and contraction of blood vessels, and always maintain appropriate contact with the blood vessel wall.

[0064] In a preferred embodiment of this invention, the mounting plane of the helical skeleton is perpendicular to the longitudinal axis of the guidewire, i.e., the helical plane is parallel to the cross-section of the target blood vessel. The helical skeleton is fixedly connected to the core material exposed at the end of the transition section 2 through its inner end, i.e., the helical starting end. The connection method uses laser micro-spot welding or high-strength biocompatible adhesive. Laser micro-spot welding uses precision laser welding equipment to uniformly weld 2-4 weld points on the circumference where the ring and the core wire contact. The weld point diameter is about 0.03 mm, and the penetration depth is controlled within 30% of the core wire diameter to ensure connection strength without damaging the mechanical properties of the core wire. The biocompatible adhesive, on the basis of welding, or medical-grade epoxy resin adhesive alone, fills and cures the gap between the ring and the core wire to form a smooth transition adhesive layer, further dispersing stress and isolating blood contact.

[0065] Furthermore, the outermost end of the helical skeleton, i.e., the end of the outermost coil, is a completely free end, not connected to any structure, ensuring that the helix can freely and uniformly expand and contract. At the free end, a streamlined leader 52 is connected. The streamlined leader 52 is made of flexible polyurethane and is fixed to the end of the helix by molding or adhesive. Its shape is a smooth hemispherical or ellipsoidal shape, used to reduce resistance when inserted into the blood vessel and avoid damage to the vascular endothelium.

[0066] In this embodiment, the fiber optic pressure sensor 51 is used to accurately measure blood flow pressure. This embodiment preferably employs a miniature fiber optic FP (Fabry-Perot) interferometric pressure sensor. Preferably, it is the FOP-M series pressure sensor from FISO Technologies.

[0067] Reference Figure 2 As shown, the fiber optic pressure sensor 51 is encapsulated within a miniature cylindrical polymer protective housing, the housing material of which can be polycarbonate or polyetheretherketone. It is fixed to the outer wall of the second of three turns of the Archimedes spiral skeleton 5 using a biocompatible adhesive. Specifically, the side of the sensor housing is bonded to the side of the spiral wire, ensuring that the plane of the sensor's pressure-sensing diaphragm, typically a thin film at the sensor's front end, is parallel to the spiral plane, i.e., parallel to the cross-section of the blood vessel, and that the diaphragm surface faces the expected direction of blood flow, typically opposite to the distal end of the guidewire. This ensures that the pressure-sensing diaphragm can directly and efficiently sense blood flow pressure.

[0068] In this embodiment, refer to Figure 3 As shown, the composite probe 6 is located at the physical furthest end of the guidewire and includes a miniature cantilever beam 61 formed at the end of the single-mode fiber, and at least three fiber Bragg grating sensors 62 disposed on the circumference of the root of the miniature cantilever beam 61 for calculating the three-dimensional force vector. Its structure is based on micro / nano fiber fabrication technology, and its specific configuration is as follows:

[0069] A standard single-mode optical fiber with a cladding diameter of 125 μm and a diameter of approximately 250 μm after coating is taken. One end is processed using chemical etching or femtosecond laser micromachining techniques to form a slender micro cantilever beam 61.

[0070] An exemplary chemical etching process involves immersing the end of an optical fiber in a hydrofluoric acid buffer solution. By utilizing the different etching rates of the fiber cladding (silica) and the coating (acrylate) to hydrofluoric acid, and by controlling the etching time and solution concentration, a silica cantilever beam with a uniform diameter and a tip size between 50 and 100 μm can be manufactured.

[0071] The fiber Bragg grating (FBG) is inscribed on the root circumference of the micro cantilever beam 61. The specific process is as follows: After the micro cantilever beam 61 is formed, a phase mask method combined with ultraviolet laser inscription technology is used. The root region of the micro cantilever beam 61 is placed close to a phase mask with a specific period. The ultraviolet laser forms interference fringes in the fiber core through the mask, thereby inscribing a grating structure with periodic modulation of refractive index.

[0072] It should be noted that, in order to achieve three-dimensional force sensing, at least three FBGs need to be inscribed at specific spatial angles on the circumference of the same cross-section at the root of the micro cantilever beam 61. Preferably, the three FBGs are inscribed at equal intervals of 120°, and the grating region axis of the three FBGs is parallel to the axis of the micro cantilever beam 61, but their positions on the circumference are different. The grating region length of each FBG should be as short as possible to approximate point measurement, preferably less than 100 μm. The center wavelengths of the three FBGs should be staggered, preferably set near 1510 nm, 1550 nm and 1590 nm respectively, to facilitate wavelength division multiplexing demodulation.

[0073] The processed fiber segment with micro cantilever beam 61 and FBG is fused to the main fiber serving as the sensing channel within the guidewire body via a flexible, narrow-diameter transition fiber. The entire composite probe 6 is encapsulated within a polymer protective sleeve, with only the free end of the micro cantilever beam 61 exposed to contact the tissue. The outer diameter of the protective sleeve smoothly transitions to the polymer sheath of the sensing segment 3 at the guidewire tip.

[0074] In this embodiment, the sensing fiber connecting the fiber optic pressure sensor 51 and the composite probe 6 requires protective routing inside the guide wire. The fiber optic cable leading from the composite probe 6, i.e., the pigtail of the micro cantilever beam 61 fiber, and the pigtail leading from the fiber optic pressure sensor 51 first converge inside the polymer sheath of the sensing section 3 at the head end. The specific routing path is as follows: the pigtail of the fiber optic pressure sensor 51 first runs a short section along the spiral that fixes it, then bends 90° through a flexible polymer sheath, allowing it to emerge axially from the spiral plane and pass through the inner center region of the spiral. The pigtail of the composite probe 6 extends directly backward from its farthest end. The two fibers converge near the center of the inner spiral skeleton.

[0075] Further, the merged fiber bundle enters transition section 2. In transition section 2 and near-end push section 1, the fiber bundle is placed within one or more miniature protective tubes, or routed along pre-machined miniature grooves on the surface of the core wire 4, and secured with flexible adhesive. The protective tubes or grooves provide mechanical protection for the fiber and isolate it from direct interference from external stresses. The fiber bundle is finally led out from a dedicated connector near the guide wire, such as a standard fiber optic active connector FC / APC, and connected to an external optical signal demodulator.

[0076] The guidewire operation process is as follows: The operator manipulates the guidewire, and the proximal advancement segment 1, with its rigidity and hydrophilic coating, smoothly passes through the proximal opening of the pre-placed delivery catheter. Since the inner diameter of the catheter is larger than the outer diameter of the spiral skeleton in its free state, during insertion, the spiral skeleton 5 is radially constrained by the inner wall of the catheter, compressed into an axially extending, slender shape, and tightly adheres to the inner wall of the catheter. The gradual design of the transition segment 2 ensures that the thrust and torque are smoothly transmitted to the flexible tip sensing segment 3. When the distal end of the catheter reaches the predetermined position, the operator fixes the catheter and begins to slowly advance the guidewire. The tip sensing segment 3 of the guidewire first emerges from the distal end of the catheter. As the guidewire continues to advance, the Archimedes spiral skeleton 5 gradually detaches from the catheter constraint, and its outer ring first contacts the blood in the blood vessel and begins to expand. Due to the superelasticity of the nickel-titanium alloy, the spiral skeleton rapidly returns to the preset planar spiral shape within 1-2 seconds. If the blood vessel diameter is 4 mm, the vessel wall will apply uniform radial pressure to the outer coil of the spiral, forcing the spiral to contract symmetrically to approximately 4 mm. During this process, the geometric symmetry of the spiral automatically adjusts its center to the geometric center of the blood vessel lumen. The fiber optic pressure sensor 51, fixed on the second coil of the spiral, is then stably suspended in the center of the blood flow. Its pressure-sensing diaphragm directly senses the pulsating blood flow pressure and outputs a pure pressure signal, eliminating the artifacts caused by the traditional guidewire adhering to the vessel wall.

[0077] Meanwhile, regardless of the adjustment of the spiral skeleton, the composite probe 6 at the very tip of the guidewire is always exposed at the front. If the guidewire tip encounters a bifurcation point during advancement, the microcantilever beam 61 of the composite probe 6 will be subjected to a major axial force; if the tip grazes the sidewall of the vessel, the microcantilever beam 61 will be subjected to lateral forces and possible shear moments. Any strain at the root of the microcantilever beam 61 will simultaneously affect the three spatially distributed FBGs inscribed thereon. Due to the different angular relationships between the three FBGs and the neutral axis of the microcantilever beam 61, they will experience different strain combinations, including axial strain and bending strain.

[0078] In some specific implementations, in order to achieve the conversion from FBG wavelength variation to three-dimensional force vector, the composite probe 6 needs to be calibrated beforehand to establish a conversion matrix. The specific calibration method is as follows:

[0079] a. Calibration system setup: Fix the composite probe 6 onto the worktable of a high-precision six-axis force / torque sensor. Connect an external demodulator to the probe's optical fiber to monitor the center wavelengths λ1, λ2, and λ3 of the three FBGs in real time.

[0080] b. Apply and record known forces: Using a micro-motion platform, apply a series of pure axial forces F of known magnitude to the tip of the micro cantilever beam 61 of the composite probe 6 along the pre-set X, Y, and Z axes of a rectangular coordinate system. z And pure lateral force F x ,F y Simultaneously, a torque can be applied around the axis for more complete calibration. Record the wavelength changes Δλ1, Δλ2, and Δλ3 of the three FBGs each time a force is applied.

[0081] c. Establishing the mathematical model and calculating the transformation matrix: Assuming the system is linear under small strain, the wavelength changes of the three FBGs and the three-dimensional force components have the following relationship:

[0082] ;in, It is a 3×3 calibration matrix, i.e., a sensitivity matrix; the specific element values ​​of the matrix can be solved by fitting the calibration experimental data using the least squares method.

[0083] d. Temperature Compensation: Since FBGs are also sensitive to temperature, calibration must be performed in a constant temperature environment, or the wavelength drift caused by temperature must be recorded simultaneously. In practical applications, a fourth reference FBG (inscribed on a stress-free part, such as the transition fiber near the fusion splice) can be used to monitor pure temperature changes and compensate for them during the calculation.

[0084] In actual surgery, the external demodulator acquires the wavelengths of the three working FBGs in real time. After subtracting the temperature compensation, the wavelength change vector caused by force is obtained. Using a pre-stored calibration inverse matrix This allows for the real-time calculation of the three-dimensional contact force vector acting on the probe tip. This vector information can be displayed in real time on the surgical navigation interface, providing force feedback to the surgeon.

[0085] Example 2:

[0086] The platform basis of this embodiment is the same as that of Embodiment 1, including a guidewire body with a proximal pushing section 1, a transition section 2, and a polymer tip sensing section 3, as well as an Archimedes spiral skeleton 5 and an optical fiber pressure sensor 51. However, in order to obtain richer and more accurate contact mechanics information, especially including torque information, this embodiment optimizes the composite probe 6. The traditional three-FBG micro cantilever beam 61 structure mainly solves the concentrated forces in three directions, but when the contact point is not exactly located on the tip axis of the micro cantilever beam 61, or when the tissue surface is irregular, a torque load will be generated, and a simple force vector is insufficient to fully describe the contact state. Therefore, the core of this embodiment is: to design the composite probe 6 to be able to simultaneously solve three-dimensional forces (F... x ,F y ,F z ) and three-dimensional torque (M x M y M z The six-dimensional force sensor is based on the principle of arranging more FBG sensing units on the micro cantilever beam 61. By measuring the strain distribution at different positions on the micro cantilever beam 61, the complete force and moment load acting on the tip can be inferred.

[0087] Specifically, the composite probe 6 in this embodiment adopts the following structure: The composite probe 6 is still based on a micro cantilever beam 61 fabricated from the end of a single-mode fiber. The length of the micro cantilever beam 61 is slightly longer than that in Embodiment 1 to provide a more pronounced strain gradient. Instead of inscribing an FBG on only one cross-section at the root, a set of FBGs is inscribed on two different cross-sections along the axial direction of the micro cantilever beam 61. For example, the first cross-section is located 100 μm from the fixed end (root), and the second cross-section is located 400 μm from the fixed end. On each cross-section, three FBGs are inscribed at 120° intervals, for a total of six FBGs.

[0088] Furthermore, the center wavelengths of the six FBGs need to be sufficiently separated for wavelength division multiplexing demodulation, set around 1510, 1525, 1540, 1555, 1570, and 1585 nm respectively. When the tip of the micro cantilever beam 61 is subjected to a combined force and moment, a complex distribution of linear strain (caused by force) and bending strain (caused by both force and moment) is generated inside the beam. The strain state of the cross-section differs at different axial positions. By measuring the wavelength changes of the six FBGs across two cross-sections, richer strain information can be obtained.

[0089] Furthermore, the calibration process is more complex than in Example 1, requiring the establishment of a 6×6 calibration matrix. The wavelength variation of the six FBGs With six-dimensional load Connecting them: .

[0090] During calibration, a six-axis force sensor is required to systematically apply known pure force and pure torque components to the probe tip, and record the responses of six FBGs under each load. Through extensive calibration experiments and data fitting (such as multiple linear regression), the complete sensitivity matrix is ​​solved. and its inverse matrix .

[0091] In practice, the demodulator acquires six wavelengths in real time and calculates the six-dimensional load using the following formula:

[0092] .

[0093] Furthermore, the operator can not only know how much force is applied to the tip, but also whether there is a torque that causes the tip of the guidewire to twist or bend, thus making a more precise judgment on the contact posture between the tip and the tissue, such as whether it is parallel and close, or whether there is a tendency to slide laterally.

[0094] 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.

[0095] 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. An integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure, comprising a proximal push section, a transition section, and a head-end sensing section arranged sequentially from proximal to distal end, wherein a core wire is disposed inside the guidewire, the core wire passing through the proximal push section and the transition section, characterized in that, Also includes: An Archimedes spiral framework, disposed on the head-end sensing segment, is deployed upon release into the blood vessel to adaptively position at least a portion of the head-end sensing segment in the central region of the blood vessel through its symmetrical radial elastic support force. A fiber optic pressure sensor, fixed in the middle section of the Archimedes spiral skeleton, is used to sense the fluid pressure at its location. A composite probe, located at the farthest end of the guidewire, is used to sense the three-dimensional contact force vector when the tip of the guidewire comes into contact with the tissue. The Archimedes spiral skeleton works in conjunction with the composite probe to provide spatial position and mechanical contact information of the guidewire tip within the blood vessel.

2. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 1, characterized in that: The Archimedes spiral skeleton is made of a superelastic material, and its outer diameter in the free state is slightly larger than the expected diameter of the target blood vessel.

3. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 2, characterized in that: The Archimedes spiral skeleton is a two-dimensional planar spiral structure formed by heat setting of nickel-titanium alloy wire, and its spiral plane is perpendicular to the axis of the guide wire.

4. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 3, characterized in that: The Archimedes spiral skeleton is fixedly connected to the core material of the transition section through its inner end, and its outer end is a free end.

5. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 1, characterized in that: The fiber optic pressure sensor is a fiber optic FP interferometer sensor, which is fixedly connected to the outer side of the middle loop of the Archimedes spiral skeleton by a biocompatible adhesive, and the plane of its pressure-sensing diaphragm is parallel to the spiral plane and faces the direction of blood flow.

6. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 1, characterized in that: The composite probe includes a miniature cantilever beam formed at the end of a single-mode optical fiber, and at least three fiber grating sensors disposed on the circumference of the root of the miniature cantilever beam for calculating three-dimensional force vectors.

7. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 1, characterized in that: The outer surface of the proximal push section is provided with a hydrophilic coating.

8. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 1, characterized in that: The main body of the head-end sensing segment is made of polymer material.

9. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 1, characterized in that: The outermost free end of the Archimedes spiral skeleton is provided with a streamlined leading head; the streamlined leading head is made of polyurethane.

10. The integrated fiber optic pressure sensing guidewire based on an Archimedes ring structure according to claim 1, characterized in that: The sensing fiber used to connect the fiber pressure sensor and the composite probe passes through a channel inside the head end sensing section, the transition section, and the proximal push section, and finally exits from the proximal end of the guidewire.

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