Laser ablation needle and method of manufacturing a laser ablation needle
Patent Information
- Application Number
- CN202611376304.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-09-07
- Publication Date
- 2026-10-09
Smart Images
Figure CN122874129A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of medical device technology, and in particular to a laser ablation needle and a method for manufacturing the laser ablation needle. Background Technology
[0002] In the field of minimally invasive interventional therapy for tumors and soft tissues, thermal ablation technology is widely used, with radiofrequency ablation (RFA) and microwave ablation (MWA) being the mainstream techniques. To avoid burns to normal tissue through the puncture tract caused by overheating of the needle shaft, these devices often require an external water-cooling circulation system to remove heat from the needle body. This not only increases the outer diameter of the puncture needle but also complicates preoperative preparation. Furthermore, radiofrequency ablation relies on high-frequency current to cause tissue molecules to vibrate and generate heat. During the procedure, a negative electrode plate needs to be attached to the patient's skin to form an electrical circuit, which poses certain safety risks.
[0003] Compared to radiofrequency and microwave ablation, laser ablation (LA) technology uses optical fibers to deliver high-energy laser light to the target tissue, rapidly heating the local area and inducing coagulative necrosis of tumor cells. It possesses inherent advantages such as high energy focusing, good directionality, no current flowing through the body, and excellent compatibility with magnetic resonance imaging, making it a promising candidate for minimally invasive treatment in delicate anatomical areas such as the brain, thyroid, and liver. However, existing laser ablation needles still have many inherent defects in structural design and clinical performance, limiting their treatment precision, safety, and reusability.
[0004] Firstly, most existing laser ablation needles employ a direct laser irradiation of the target tissue, using human tissue as the photothermal conversion carrier. Due to significant differences in density, water content, and optical absorption characteristics among different tissues, it is difficult to precisely control the heating rate and temperature range in clinical practice. This can easily lead to localized overheating and carbonization of the target area, resulting in obstructed heat conduction, uneven ablation range, and affecting the accuracy and thoroughness of treatment. Some solutions add a laser-mediated cap to improve photothermal conversion efficiency, but the reliable connection of the mediator and the axial insulation of the needle body remain unresolved, still failing to prevent thermal damage to non-target tissues caused by heat conduction along the needle body.
[0005] Secondly, existing laser ablation needles lack sufficient mechanical strength, requiring the establishment of a working channel through a puncture cannula (guide needle). In clinical practice, a rigid metal cannula is first inserted to the target, the inner core is removed, and a working sheath is established before the laser fiber is inserted through the sheath. This process is complex, and heat from the target area is easily conducted along the metal needle body to the handle side, potentially causing non-specific thermal damage to normal tissues, blood vessels, and nerves along the puncture path. This risk is particularly pronounced in high-risk anatomical areas with dense nerve and blood vessel networks. A few approaches introduce ceramic materials solely for insulation or positioning, failing to utilize their low thermal conductivity to construct an integrated structure that combines load-bearing and thermal insulation functions, thus failing to effectively block axial heat diffusion.
[0006] Furthermore, existing ablation needles generally use adhesive or threaded connections for assembly. Under repeated thermal cycling conditions, the adhesive materials are prone to thermal aging and failure, and the threaded connections are prone to loosening or even component detachment. This poses both clinical safety risks and makes it difficult to meet the reliability requirements for long-term, high-frequency reuse of the device. At the same time, most existing structures do not integrate puncture and ablation functions. During the procedure, the fiber optic cable must be inserted under the guidance of a puncture needle, which is cumbersome and not conducive to precise intraoperative control. Summary of the Invention
[0007] This invention provides a laser ablation needle and a method for manufacturing the laser ablation needle, which to a certain extent solves the defects of unsatisfactory ablation control effect and structural reliability of laser ablation needles in the prior art, and achieves safe and precise ablation treatment and stable and durable device performance.
[0008] This invention provides a laser ablation needle, comprising a front end assembly and a rear end assembly. The front end assembly has an internal fiber optic channel for inserting an optical fiber. The front end assembly includes a needle tip and a rod connected to the rear end of the needle tip, with a connecting head at the tail end of the rod. The main body of the rear end assembly is a tubular structure, and the front end of the rear end assembly has a precision inner hole. The diameter of the precision inner hole at room temperature is smaller than the outer diameter of the connecting head. The tail end inner hole of the rear end assembly is used to insert and protect the internal optical fiber. The rear end assembly is fitted onto the outer periphery of the connecting head through the precision inner hole to form a tight fit, and the coefficient of thermal expansion of the front end assembly is greater than that of the rear end assembly.
[0009] According to one embodiment of the present invention, the connecting head is a cylindrical structure with a uniform outer diameter along the axial direction or with a gradually increasing outer diameter; and / or, the outer surface of the connecting head is provided with a groove or texture structure.
[0010] According to one embodiment of the present invention, the end of the optical fiber is in close contact with the light-absorbing structure at the inner end of the optical fiber channel, or maintains a distance L from the light-absorbing structure.
[0011] According to one embodiment of the invention, the front-end component is made of a metallic material; and / or, the back-end component is made of bio-inert ceramic.
[0012] According to one embodiment of the present invention, the bio-inert ceramic is selected from any of the following, and the present invention also provides one or a combination of two: zirconia-based ceramics and alumina-based ceramics.
[0013] According to one embodiment of the present invention, the outer periphery of the connecting head is provided with at least one radially outwardly protruding snap-fit protrusion; the rear end assembly is provided with a snap-fit structure that cooperates with the snap-fit protrusion.
[0014] According to one embodiment of the present invention, the connecting head is provided with an outwardly protruding positioning protrusion; the front end of the rear end component is provided with a positioning groove that cooperates with the positioning protrusion; the positioning groove extends along the axial direction of the rear end component and has a groove width and groove depth that match the positioning protrusion.
[0015] The present invention also provides a method for manufacturing a laser ablation needle, wherein the laser ablation needle is the laser ablation needle of the above embodiment, and the method includes: heating the rear end component to cause the rear end component to expand due to heat; axially sleeve the heated rear end component onto the tail end of the front end component; cooling the rear end component to form an interference fit connection between the cooled and shrunken rear end component and the front end component.
[0016] According to one embodiment of the present invention, in the step of heating the rear-end component, only the rear-end component is heated, while the front-end component is at room temperature or cooled to below room temperature; after the precision inner hole of the rear-end component expands to an inner diameter larger than the outer diameter of the connecting head of the front-end component, an axial sleeve operation is performed.
[0017] According to one embodiment of the present invention, in the step of heating the rear end assembly, the front end assembly and the rear end assembly are heated simultaneously; wherein, the heating temperature of the rear end assembly is higher than the heating temperature of the front end assembly, so that after heating, the inner diameter of the precision inner hole of the rear end assembly is larger than the outer diameter of the connecting head of the front end assembly, thereby forming an assembly gap that can be axially fitted.
[0018] The laser ablation needle and its manufacturing method provided by this invention employ a material design with differentiated coefficients of thermal expansion for the front-end and rear-end components. The front-end component has a higher coefficient of thermal expansion than the rear-end component, coupled with a corresponding thermal assembly process. During manufacturing, the rear-end component is first heated to expand its precision inner hole, then axially fitted onto the connecting head of the front-end component. After cooling and contraction, a strong initial interference fit is formed. In clinical operation, when the laser energy raises the temperature of the front-end component, due to its higher coefficient of thermal expansion, the radial expansion of the connecting head is greater than that of the inner hole of the rear-end component. This causes the interference fit at the interface to increase further with rising operating temperature, resulting in a self-reinforcing, tighter hold that increases with increasing heat load. This solution provides a connection method between the front-end and rear-end components, avoiding the defects of traditional adhesive and threaded connections that are prone to aging, loosening, or even detachment under repeated thermal cycling conditions. This effectively improves the structural reliability, clinical safety, and long-term reusability of the laser ablation needle. Furthermore, the rear-end component provides sufficient mechanical rigidity and stress support, eliminating the need for an additional puncture needle and achieving integrated puncture and ablation. Finally, by making full use of the low thermal conductivity of the back-end components, a thermal barrier is constructed between the front-end metal ablation zone and the back-end puncture path, which to a certain extent blocks the axial thermal diffusion of the needle body, reduces the problem of thermal damage to normal tissues during the operation, and improves the safety and accuracy of the operation. Attached Figure Description
[0019] To more clearly illustrate the technical solutions in this 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 some embodiments of this invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0020] Figure 1 This is one of the structural schematic diagrams of the laser ablation needle provided by the present invention.
[0021] Figure 2 This is a partial structural schematic diagram of the laser ablation needle provided by the present invention.
[0022] Figure 3 This is a partial exploded view of the laser ablation needle provided by the present invention.
[0023] Figure 4 This is a schematic diagram of the front end component of the laser ablation needle provided by the present invention.
[0024] Figure 5 This is a schematic diagram of the rear-end component of the laser ablation needle provided by the present invention.
[0025] Figure 6This is the second schematic diagram of the structure of the laser ablation needle provided by the present invention.
[0026] Figure 7 yes Figure 6 The diagram shows a cross-sectional view of the laser ablation needle.
[0027] Figure 8 yes Figure 6 The diagram shows the exploded structure of the laser ablation needle.
[0028] Figure label: 10. Front-end component; 11. Needle tip; 12. Rod; 13. Connecting head; 14. Fiber optic channel; 15. Light-absorbing structure; 20. Rear-end component; 21. Precision inner hole; 22. Tail inner hole; 31. Snap-fit protrusion; 32. Snap-fit structure; 33. Positioning protrusion; 34. Positioning groove. Detailed Implementation
[0029] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.
[0030] The specific terms used in this specification are for illustrative purposes only and are not intended to limit the illustrated embodiments. For example, expressions such as "same" and "identical" not only indicate a strictly identical state, but also indicate a state with tolerances or differences in the degree of functionality. For example, expressions indicating relative or absolute arrangement such as "in a certain direction," "along a certain direction," "side by side," "perpendicular," "centered on," "concentric," or "coaxial" not only strictly indicate such an arrangement, but also indicate a state of relative displacement by tolerances or angles or distances with the same degree of functionality.
[0031] The terms “center,” “longitudinal,” “lateral,” “length,” “width,” “thickness,” “upper,” “lower,” “front,” “rear,” “left,” “right,” “vertical,” “horizontal,” “top,” “bottom,” “inner,” “outer,” “clockwise,” “counterclockwise,” “axial,” “radial,” and “circumferential” indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the present invention and simplifying the description, and are not intended to indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting the present invention.
[0032] Furthermore, features specified as "first" or "second" may explicitly or implicitly include one or more of those features. In the description of this invention, unless otherwise stated, "multiple" means two or more. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly specified. In the description of the embodiments of this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, B1 and / or B2 can represent: B1 existing alone, B1 and B2 existing simultaneously, and B2 existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.
[0033] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.
[0034] While existing laser ablation needles have made some progress in optical transmission efficiency and ease of clinical operation, their structural design still has several key limitations. Traditional designs often employ all-metal or metal-dominated continuous heat conduction paths. During laser operation, heat generated can easily be conducted along the needle body to the distal end, causing thermal damage to normal tissues outside the target area along the puncture path, especially in areas with dense nerves and blood vessels. Furthermore, components generally rely on adhesive or threaded connections, which are prone to aging, loosening, or even detachment under repeated heating and cooling cycles, making it difficult to guarantee structural integrity and safety under high-frequency use.
[0035] To address the aforementioned issues, this invention proposes a laser ablation needle and its manufacturing method, aiming to improve aspects such as material matching, thermal management, and connection mechanisms. By rationally configuring materials with high and low coefficients of thermal expansion and combining them with an interference fit process, a reliable mechanical connection is formed not only at room temperature but also, under high-temperature operating conditions, the greater thermal expansion of the front-end components achieves a self-reinforcing clamping effect, significantly improving thermal cycling durability. Simultaneously, by utilizing non-metallic materials with low thermal conductivity, the heat conduction path to non-target areas is effectively blocked, balancing thermal insulation and structural load-bearing functions. This ensures treatment precision while improving the overall safety and clinical applicability of the device.
[0036] The following is combined Figures 1 to 5 This invention describes specific embodiments of the laser ablation needle.
[0037] like Figure 1 , Figure 2 , Figure 3 , Figure 4 and Figure 5 As shown, this invention provides a laser ablation needle, including a front-end component 10 and a rear-end component 20. The front-end component 10 has an internal fiber optic channel 14 for inserting optical fibers. The front-end component 10 includes a needle tip 11 and a rod 12 connected to the rear end of the needle tip 11, with a connecting head 13 at the tail end of the rod 12. The main body of the rear-end component 20 is a tubular structure. A precision inner hole 21 is machined inside the front end of the rear-end component 20. The diameter of the precision inner hole 21 at room temperature is smaller than the outer diameter of the connecting head 13. The tail inner hole 22 of the rear-end component 20 is used to insert and protect the internal optical fiber. The rear-end component 20 is fitted onto the outer periphery of the connecting head 13 through the precision inner hole 21 to form a tight fit. The thermal expansion coefficient of the front-end component 10 is greater than that of the rear-end component 20. Specifically, this structure adopts the principle of thermal interference fit, pre-setting the front-end component 10 and the rear-end component 20 to a dimensional interference state at room temperature. Through the difference in the thermal expansion coefficients of the materials, a double-strengthened mechanical connection is achieved during assembly and use. High bonding strength is formed by cooling and shrinkage during initial assembly. In operation, the increased thermal expansion at the front end dynamically enhances the interfacial compressive stress, achieving a self-locking effect that tightens as it heats up. Preferably, the inner diameter of the fiber optic channel 14 matches the inner diameter of the tail bore 22, thus forming a complete channel structure for accommodating the optical fiber in the installed state. Furthermore, the shape of the tip 11 can be customized according to application requirements; for example, it can be designed as follows: Figure 4 The cone shape shown can also be designed as follows: Figure 6 , 7 The multifaceted cone shown in Figure 8.
[0038] In practical applications, the aforementioned laser ablation needle uses the front component 10 as the ablation part that directly acts on the lesion, and the rear component 20 as the handle connecting section for the operator to hold. The two are firmly connected as one unit through a heat-fitting interference fit. Under normal conditions, the interference fit at room temperature can provide sufficient static friction and bonding strength. However, during laser ablation, the front end heats up due to the absorption of high-energy laser light (typically reaching over 60°C). Its large coefficient of thermal expansion causes the radial expansion of the connecting head 13 to exceed the expansion of the precision inner hole 21 of the rear component 20, thereby further increasing the compressive stress between the contact surfaces and significantly improving the connection reliability under high-temperature conditions. Simulated thermal cycling tests (20–300°C, 1000 cycles) have verified that the connection parts of this structure show no signs of loosening or performance degradation, which helps overcome the defects of traditional adhesive or threaded connections that are prone to aging and loosening under repeated thermal shock.
[0039] In one embodiment, this thermally fitted interference fit technique is applied to the connection of dissimilar materials between the metal front-end component 10 and the ceramic rear-end component 20. By actively utilizing the significant difference in the coefficients of thermal expansion between the metal and ceramic, the metal component expands more when heated, thereby further pressing the ceramic inner hole at the operating temperature and achieving a dynamically enhanced fastening effect. This connection method eliminates the need for adhesives, complex threads, or additional locking structures, relying solely on a pure mechanical interference fit. This not only simplifies the overall structure but also avoids the aging problems of organic adhesive layers during high-temperature sterilization or long-term use, exhibiting excellent chemical stability and the ability to withstand high-temperature and high-pressure sterilization at 135°C. Simultaneously, the ceramic rear-end component 20, due to its low thermal conductivity (e.g., approximately 2–3 W / m·K), forms an efficient thermal barrier at the tail end of the metal rod 12, significantly inhibiting heat conduction towards the handle and reducing the risk of thermal damage to non-target tissues.
[0040] Furthermore, according to a laser ablation needle of the present invention, the precision inner hole 21 and the connecting head 13 preferably form an interference fit structure. In one embodiment, the radial interference of the above-mentioned interference fit structure is preferably in the range of 0.01 mm to 0.09 mm. This radial interference ensures assembly feasibility while taking into account the initial bonding strength at room temperature and the dynamic enhancement effect under high temperature working conditions. Too small an interference may lead to insufficient initial clamping force, affecting structural stability; while too large an interference will increase assembly difficulty and even cause local plastic deformation or microcracks in the material. Therefore, controlling the interference within a reasonable range (which can be determined according to material characteristics or actual measurement) can achieve good process feasibility and long-term service durability while ensuring reliable mechanical connection. Preferably, the length of the rear end component 20 covering the tail end of the front end component 10 along the axial direction can be 5–20 mm to provide sufficient contact area to transfer load and maintain structural integrity under thermal cycling. Meanwhile, the radial interference is preferably controlled within the range of 0.01–0.09 mm, and precision machining is performed according to the GB / T1804-m grade tolerance standard to ensure dimensional consistency and assembly reliability in mass production. It is understood that the parameter ranges shown in the various embodiments of the present invention are example parameter ranges of preferred embodiments of the present invention, and the present invention is not limited thereto. Any equivalent changes to the parameters based on the technical solution of the present invention are within the protection scope of the present invention.
[0041] like Figure 3 and Figure 4As shown, according to a laser ablation needle of the present invention, the connecting head 13 is a cylindrical structure with a uniform outer diameter along the axial direction or a gradually increasing outer diameter; and / or, the outer surface of the connecting head 13 is provided with grooves or textured structures. Specifically, using a cylindrical connecting head 13 with a uniform outer diameter is beneficial for achieving a uniform interference contact pressure distribution and simplifying processing and assembly control; while using a tapered or stepped structure with a gradually increasing outer diameter along the axial direction can further enhance the axial locking force during thermal expansion. In addition, adding grooves, knurling, mesh patterns or other micro-textured structures to the outer surface of the connecting head 13 can not only increase the mechanical interlocking force of the mating interface and suppress relative slippage, but also improve stress release during thermal cycling without significantly weakening the structural strength. The above structures, together with the thermal interference fit, work synergistically to improve the connection reliability and long-term stability of the laser ablation needle in harsh clinical environments such as high temperature, high humidity and repeated sterilization.
[0042] According to a laser ablation needle of the present invention, the end of the optical fiber is closely attached to the light-absorbing structure 15 at the inner end of the optical fiber channel 14, or maintains a distance L from the light-absorbing structure 15. By adjusting the relative position between the output end of the optical fiber and the light-absorbing structure 15, the laser energy conversion efficiency and thermal distribution characteristics can be optimized. When the end of the optical fiber is closely attached to the light-absorbing structure 15, the laser energy can be efficiently absorbed and concentrated into heat energy, which is suitable for local ablation scenarios requiring high power density; while when a certain distance L is maintained between the two, some laser light can be scattered or form a light spot expansion in the gap, which helps to expand the thermal action area, reduce the local peak temperature, and thus reduce the risk of carbonization or tissue rupture. The distance L can be adjusted in the range of 0.1 mm to 10.0 mm according to clinical needs. For example, in delicate nerve ablation, L=0.8 mm can be selected to achieve gentle heating.
[0043] According to a laser ablation needle of the present invention, the optical fiber is fixed within the optical fiber channel 14 by potting adhesive or increasing friction. The potting process not only firmly anchors the optical fiber to the center of the channel, preventing axial displacement or radial wobble during operation or thermal cycling, but also, by selecting encapsulating adhesives with matching refractive indices, high thermal stability, and biocompatibility (such as medical-grade epoxy resin or silicone), further improves light transmission efficiency and prevents external liquid intrusion. Furthermore, the adhesive layer also buffers thermal stress, alleviating the mechanical load on the brittle optical fiber caused by the thermal expansion of the front-end component 10, thereby ensuring the structural integrity and optical performance stability of the optical fiber during repeated high-temperature sterilization and long-term use. Fixing the fiber by increasing friction at the rear end reduces the processing difficulty and production cost of the ablation needle, facilitates the compression of the ablation needle size, and reduces tissue damage caused by puncture. Specifically, increasing the friction at the rear end of the optical fiber can include increasing the radial dimension of the rear end and processing friction structures, such as rough particle structures or friction texture structures, on the outer surface of the rear end.
[0044] According to a laser ablation needle of the present invention, the front end component 10 is made of a metallic material, which may be austenitic stainless steel, titanium and titanium alloys, or nickel-titanium alloys. Preferably, stainless steel (such as 304 or 316L medical grade) is used, which is beneficial for the front end component 10 to possess excellent biocompatibility, corrosion resistance, and sufficient rigidity and strength, making it suitable for minimally invasive interventional procedures where high structural stability is required. Using titanium and titanium alloys allows the coefficient of thermal expansion of the front end component to be closer to that of the rear end component (zirconia ceramic), resulting in better thermal cycling fatigue life and superior biocompatibility. Nickel-titanium alloys, on the other hand, can provide superelasticity and shape memory properties in specific applications, facilitating precise access to the lesion site via a bending path. Furthermore, the aforementioned metallic materials have high thermal conductivity and a controllable coefficient of thermal expansion, which can effectively conduct and locally concentrate the heat generated by the laser, achieving efficient and controllable tissue ablation.
[0045] In a preferred embodiment, the ablation zone is made of medical-grade 304 stainless steel, with an average coefficient of linear expansion of approximately 17 × 10⁻⁶. -6 / ℃, which not only meets the requirement of differentiated thermal expansion matching with low expansion coefficient back-end components 20 (such as ceramics), but also has good biocompatibility, mechanical strength and stable absorption and conduction of laser energy, thereby improving ablation efficiency and instrument reliability while ensuring surgical safety.
[0046] According to a laser ablation needle of the present invention, the rear component 20 is made of bio-inert ceramic, which may be selected from: zirconia-based ceramic, alumina-based ceramic, or a combination thereof. The zirconia-based ceramic may be one of Y₂O₃ partially stabilized zirconia, CeO₂ partially stabilized zirconia, or alumina-toughened zirconia (ATZ), preferably with a zirconia phase content ≥80wt%. The alumina-based ceramic is preferably 95% or higher high-purity alumina, or zirconia-toughened alumina (ZTA), wherein the ZrO₂ toughening phase content is 5-30wt%. Ceramic materials not only possess excellent electrical insulation and biocompatibility, meeting the stringent standards for medical devices, but also, due to their high hardness and wear resistance, can maintain precise dimensional fit over a long period, ensuring structural stability after repeated assembly and sterilization. Furthermore, ceramics have significantly lower thermal conductivity than metals and controllable thermal expansion characteristics, enabling them to effectively block heat transfer when combined with the metal front component 10, and to achieve a dynamic self-tightening connection mechanism through the difference in thermal expansion coefficients.
[0047] The rear-end component 20, serving as the grip, is preferably made of 3Y-ZrO2 material, which has a thermal conductivity of approximately 2.5 W / (m·K), lower than that of stainless steel and other metal materials, thus forming a highly efficient thermal barrier layer. In a preferred embodiment of this invention, tests showed that when the stainless steel needle tip 11 reaches a working temperature of 100°C, the outer surface temperature of the end of the ceramic rear-end component 20 (near the handle) can be controlled below 40°C. This is superior to traditional solutions such as heat-insulating coatings or air gaps, preventing burns to the operator and improving surgical safety.
[0048] Furthermore, the aforementioned preferred 3Y-ZrO2 material has an average coefficient of linear expansion of approximately 10 × 10⁻⁶. -6 / ℃, while the average linear expansion coefficient of the 304 stainless steel used in the front-end ablation section is approximately 17×10. -6 The temperature difference between the two is significant. During room temperature assembly, an initial clamping force is formed between the metal and ceramic through a precisely controlled radial interference fit (e.g., 0.01–0.09 mm). When the device generates heat during operation, the front-end metal tends to expand to a greater extent due to its higher coefficient of thermal expansion. However, constrained by the rigid ceramic ring, the interfacial normal pressure further increases, leading to enhanced friction. This mechanism improves the shear resistance and anti-loosening performance of the connection interface under high-temperature conditions.
[0049] In addition to the preferred option of using 304 stainless steel for the front-end components and 3Y-ZrO2 material for the back-end structure, the ablation needle can also be selected from different combinations such as 316L stainless steel with Y-PSZ (3Y-ZrO2), Ti-6Al-4V with Ce-TZP, and 316L stainless steel with ZTA (Al2O2+15%ZrO2) to achieve different levels of cost control and meet the toughness requirements of different materials.
[0050] On the other hand, the present invention also provides an embodiment in which the front-end component 10 and the rear-end component 20 are mechanically connected by a snap-fit structure 32. In this embodiment, the laser ablation needle also includes a front-end component 10 and a rear-end component 20; the front-end component 10 has an internal fiber optic channel 14 for inserting optical fibers; the front-end component 10 includes a needle tip 11 and a rod 12 connected to the rear end of the needle tip 11, and a connecting head 13 is provided at the tail end of the rod 12; the main body of the rear-end component 20 is a tubular structure, and a precision inner hole 21 is machined inside the front end of the rear-end component 20. The diameter of the precision inner hole 21 at room temperature is smaller than the outer diameter of the connecting head 13, and the tail inner hole 22 of the rear-end component 20 is used to insert and protect the internal optical fiber; the rear-end component 20 is fitted onto the outer periphery of the connecting head 13 through the precision inner hole 21 to form a tight fit, and the coefficient of thermal expansion of the front-end component 10 is greater than that of the rear-end component 20. Based on this, as Figure 6 Figure 7 and Figure 8As shown, the front-end assembly 10 has a connecting head 13 at its tail end of the rod portion 12, and at least one radially outwardly protruding snap-fit protrusion 31 on its outer periphery. The rear-end assembly 20 has a snap-fit structure 32 at its front end that mates with the snap-fit protrusion 31. The snap-fit structure 32 includes at least one of a slot, a hole, a limiting recess, or an elastic snap-fit portion disposed at the end of the rear-end assembly 20. After the rear-end assembly 20 is fitted onto the outer periphery of the connecting head 13, the snap-fit protrusion 31 and the snap-fit structure 32 cooperate with each other to limit the axial relative displacement between the front-end assembly 10 and the rear-end assembly 20, thereby achieving a mechanical connection between the front-end assembly 10 and the rear-end assembly 20.
[0051] Specifically, during the assembly process, the connecting head 13 is inserted axially into the front end of the rear end component 20, and the snap-fit protrusion 31 on the connecting head 13 undergoes radial elastic deformation; when the connecting head 13 is inserted to the predetermined position, the snap-fit protrusion 31 enters the corresponding snap-fit recess of the rear end component 20, and the snap-fit protrusion 31 and the snap-fit recess engage with each other to achieve axial positioning of the front end component 10 and the rear end component 20.
[0052] Furthermore, the connecting head 13 may be provided with an annular flange extending in the circumferential direction, a partial arc-shaped protrusion, a plurality of snap-fit protrusions spaced apart in the circumferential direction, or a plurality of snap-fit protrusions spaced apart in the axial direction; correspondingly, the rear end component 20 may be provided with an annular groove, a partial groove, a plurality of snap-fit holes, or a plurality of limiting recesses that match the above structure, so as to form different forms of snap-fit mating structures.
[0053] The aforementioned snap-fit mechanical connection structure enables a reliable connection between the front-end component 10 and the rear-end component 20 without the need for adhesives. Furthermore, the mechanical restraint between the snap-fit protrusion 31 and the snap-fit structure 32 reduces the risk of axial disengagement at the connection point. This connection method can also be used alone or in combination with the aforementioned heat-fit interference fit method to meet different assembly processes and structural reliability requirements.
[0054] Furthermore, to limit the relative circumferential rotation of the front-end component 10 and the back-end component 20 after assembly, a circumferential positioning structure may also be provided between the front-end component 10 and the back-end component 20. For example... Figure 8 As shown, the connecting head 13 of the front-end component 10 is provided with an outwardly protruding positioning protrusion 33, and the front end of the rear-end component 20 is provided with a corresponding positioning groove 34 that mates with the positioning protrusion 33. The positioning groove 34 extends along the axial direction of the rear-end component 20 and has a groove width and groove depth that match the positioning protrusion 33.
[0055] During assembly, the connecting head 13 of the front end component 10 is inserted axially into the front end of the rear end component 20, and the positioning protrusion 33 slides along the positioning groove 34 and enters the interior of the positioning groove 34. When the rear end component 20 moves to the predetermined assembly position, the positioning protrusion 33 and the positioning groove 34 form a fitting engagement, thereby limiting the circumferential relative displacement between the front end component 10 and the rear end component 20, so that the front end component 10 and the rear end component 20 maintain the predetermined circumferential relative position after assembly, and prevent the two from rotating relative to each other.
[0056] The manufacturing method of the laser ablation needle provided by the present invention will be described below. The manufacturing method of the laser ablation needle described below can be referred to in correspondence with the laser ablation needle described above.
[0057] This invention also provides a method for manufacturing a laser ablation needle, wherein the laser ablation needle is the laser ablation needle described in the above embodiment. The method includes: heating the rear end component 20 to cause it to expand due to heat; axially fitting the heated rear end component 20 onto the tail end of the front end component 10; and cooling the rear end component 20 to form an interference fit connection between the cooled and contracted rear end component 20 and the front end component 10. Specifically, this thermal fitting process fully utilizes the difference in thermal expansion coefficients between the front metal component (such as 304 stainless steel) and the rear ceramic component (such as 3Y-ZrO2). At room temperature, the inner hole of the rear ceramic component is slightly smaller than the outer diameter of the front metal connecting head 13, making direct assembly impossible. By moderately heating the ceramic rear end component 20, its inner hole temporarily expands due to thermal expansion, allowing it to be smoothly slid onto the front end component 10. After cooling, the ceramic shrinks and forms a radial clamping force on the metal, achieving a highly reliable mechanical connection without the need for additional adhesives or fasteners. This simplifies the structure and avoids the risk of adhesive aging or interface debonding.
[0058] The cooling process preferably employs controlled-rate natural cooling (such as slow cooling in a static environment at room temperature) to avoid thermal shock caused by rapid cooling. Preferably, after assembly, a strength test can be performed on the laser ablation needle. For example, under standard tensile testing conditions, the axial destructive force of the connection area should not be less than 50N. An axial load is applied on a tensile testing machine until relative displacement or structural damage occurs. The recorded critical failure value must reach or exceed this threshold to ensure that the connection remains structurally intact even if accidentally stretched during clinical operations.
[0059] In the practical application of the above-mentioned heat fitting process, different heating implementation methods can be adopted according to the assembly interference, production conditions, and material temperature control requirements. According to one embodiment of the present invention, in the step of heating the rear-end component 20, only the rear-end component 20 is heated, while the front-end component 10 is at room temperature or cooled to below room temperature. After the precision inner hole 21 of the rear-end component 20 expands due to heat to an inner diameter larger than the outer diameter of the connecting head 13 of the front-end component 10, an axial fitting operation is performed. The front-end component 10 is dimensionally stable at room temperature or lower temperatures, which facilitates the formation of a repeatable and high-precision interference fit with the controlled-expansion rear-end component 20.
[0060] Furthermore, according to a method for manufacturing a laser ablation needle according to the present invention, the step of heating the rear end assembly 20 to cause it to expand thermally may include: heating the rear end assembly 20 to a specific temperature, preferably within the range of 80°C to 400°C. Within this temperature range, the linear expansion of the 3Y-ZrO2 ceramic is sufficient to increase the diameter of its precision inner hole 21 to slightly larger than the outer diameter of the connecting head 13 of the front end assembly 10, thereby achieving resistance-free assembly.
[0061] During heating, excessively high temperatures may cause a decrease in the local strength of the ceramic or create a superimposed thermal effect with the subsequent sterilization process, while excessively long holding times may lead to energy waste or heat damage to components near the front end (such as pre-installed optical fibers). Preferably, the heating temperature does not exceed 300°C and the holding time does not exceed 2 minutes, thus balancing assembly efficiency and material safety.
[0062] In addition to the above-mentioned assembly method with independent heating at one end, considering that in the actual assembly process, if the front-end component 10 and the rear-end component 20 are not precisely insulated, the front-end component 10 is easily affected by the heating process of the rear-end component 20 and passively heats up. To address this situation, according to another embodiment of the present invention, in the step of heating the rear-end component 20, the front-end component 10 can be allowed to passively heat up due to heat conduction, or it can be lightly heated; wherein it is necessary to ensure that the temperature of the rear-end component 20 is always higher than the temperature of the front-end component 10, and that the inner diameter of the precision inner hole 21 of the heated rear-end component 20 is larger than the outer diameter of the connecting head 13 of the front-end component 10, so as to form an assembly gap that allows for axial fitting. This embodiment does not require dedicated precision insulation fixtures for the two components, which can lower the threshold for assembly process implementation and adapt to different mass production processing conditions.
[0063] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
Claims
1. A laser ablation needle, characterized in that, Includes front-end components (10) and back-end components (20); The front-end component (10) has an internal optical fiber channel (14) for passing optical fibers. The front end assembly (10) includes a needle tip (11) and a rod (12) connected to the rear end of the needle tip (11), and the tail end of the rod (12) is provided with a connecting head (13). The main body of the back-end component (20) is a tubular structure. The front end of the back-end component (20) has a precision inner hole (21). The diameter of the precision inner hole (21) at room temperature is smaller than the outer diameter of the connecting head (13). The tail inner hole (22) of the back-end component (20) is used to insert and protect the internal optical fiber. The rear component (20) is fitted onto the outer periphery of the connecting head (13) through the precision inner hole (21) and forms a tight fit, and the thermal expansion coefficient of the front component (10) is greater than that of the rear component (20).
2. The laser ablation needle according to claim 1, characterized in that, The connecting head (13) is a cylindrical structure with a uniform outer diameter along the axial direction or with a gradually increasing outer diameter; and / or, The outer surface of the connecting head (13) is provided with a groove or texture structure.
3. The laser ablation needle according to claim 1, characterized in that, The end of the optical fiber is close to the light-absorbing structure (15) at the inner end of the optical fiber channel (14), or maintains a distance L from the light-absorbing structure (15).
4. The laser ablation needle according to any one of claims 1 to 3, characterized in that, The front-end component (10) is made of metal. And / or, the back-end component (20) is made of bio-inert ceramic.
5. The bio-inert ceramic material according to claim 4, characterized in that, The bio-inert ceramic is selected from any one or a combination of two of the following: zirconia-based ceramics and alumina-based ceramics.
6. The laser ablation needle according to claim 1, characterized in that, The outer periphery of the connecting head (13) is provided with at least one radially outward protruding snap-fit protrusion (31). The rear component (20) is provided with a snap-fit structure (32) that cooperates with the snap-fit protrusion (31).
7. The laser ablation needle according to claim 6, characterized in that, The connecting head (13) is provided with an outwardly protruding positioning protrusion (33). The front end of the rear component (20) is provided with a positioning groove (34) that cooperates with the positioning protrusion (33). The positioning groove (34) extends along the axial direction of the rear end assembly (20) and has a groove width and groove depth that match the positioning protrusion (33).
8. A method for manufacturing a laser ablation needle, characterized in that, The laser ablation needle is the laser ablation needle according to any one of claims 1 to 7, and the method includes: Heating the rear-end component (20) causes the rear-end component (20) to expand due to heat; The heated rear end component (20) is axially sleeved onto the tail end of the front end component (10); The rear-end component (20) is cooled so that the cooled and shrunken rear-end component (20) forms an interference fit connection with the front-end component (10).
9. The method for manufacturing a laser ablation needle according to claim 8, characterized in that, In the step of heating the rear-end component (20), only the rear-end component (20) is heated, while the front-end component (10) is at room temperature or cooled to below room temperature. After the precision inner hole (21) of the rear component (20) is heated and expanded to an inner diameter greater than the outer diameter of the connecting head (13) of the front component (10), the axial sleeve operation is performed.
10. The method for manufacturing a laser ablation needle according to claim 8, characterized in that, In the step of heating the rear-end component (20), the front-end component (10) and the rear-end component (20) are heated simultaneously. The heating temperature of the rear component (20) is higher than that of the front component (10), so that the inner diameter of the precision inner hole (21) of the rear component (20) is larger than the outer diameter of the connecting head (13) of the front component (10) after heating, so as to form an assembly gap that can be axially sleeved.