Multi-segment variable stiffness magnetically driven catheter and surgical robot

Abstract

The application discloses a multi-tube segment variable rigidity magnetic drive catheter and surgical robot. The magnetic drive catheter comprises a distal small catheter (1) and a main catheter (2), the distal small catheter is connected at the distal end of the main catheter; the distal small catheter can be controlled to change rigidity, the distal small catheter comprises a certain number of sub-tube segments (11), the sub-tube segments are sequentially connected together in a head-to-tail mode; the sub-tube segment is composed of an inner tube body and an outer tube body, the material of the outer tube body is a shape memory polymer, a heating coil (4) is arranged in the outer tube body, and annular magnets (12) are uniformly and discretely distributed on the distal small catheter. The distal small catheter in the magnetic drive catheter can control the rigidity of each part through the mode of controlling temperature, then the attitude of the distal small catheter is controlled by using the magnet at the end of the mechanical arm of the surgical robot, the catheter based on the mode has a small outer diameter and can be stretched into a small human body cavity for treatment under the premise that the inner diameter of the working channel is not reduced.

Description

Technical Field

[0001] This invention relates to a medical catheter, and more particularly to a multi-segment variable stiffness magnetically driven catheter and a surgical robot. Background Technology

[0002] A bronchoscopic robot is a transluminal surgical robotic system used for the diagnosis and treatment of lung diseases. It assists doctors in performing bronchoscopic examinations, biopsies, and treatments using robotic technology, and is particularly adept at reaching distal lung lesions that are difficult to access with traditional bronchoscopy. The bronchoscopic robot uses a flexible robotic arm to manipulate extremely thin, flexible catheters, allowing it to penetrate deep into the delicate bronchial branches of the lungs for manipulation. Currently, bronchoscopic robots are widely used, and they have demonstrated effectiveness in clinical practice, with significantly higher diagnostic rates and better complication control than traditional techniques.

[0003] The main problem at present is:

[0004] 1) Existing bronchoscopic robots use tethered catheters for attitude control. The core mechanism involves pulling on an internal guidewire (pull wire) to control the bending and turning of the distal end of the catheter. Due to the complexity of the tethered mechanical structure, the outer diameter of the catheter is relatively large, and the catheter cannot be made very thin, usually greater than 3.5 mm. This limits its ability to enter the distal airway of the bronchus (such as the subsegmental bronchus, which usually has an inner diameter of about 3.25 mm).

[0005] In addition, there are other issues, as follows:

[0006] 2) Existing catheters have fixed stiffness, either purely rigid or purely flexible, thus failing to balance flexible navigation and rigid positioning.

[0007] Specifically

[0008] To date, three bronchoscopic robotic platforms have been approved by the U.S. Food and Drug Administration (FDA) (Monarch, Ion, and Galaxy)[3]. These bronchoscopic robots have demonstrated effectiveness in clinical practice. Their diagnostic rates and complication control are significantly better than traditional techniques. However, the average outer diameter of these three bronchoscopic robots is typically greater than 3.5 mm, which limits their ability to access distal airways (such as subsegmental bronchi) with a diameter of approximately 3.25 mm. In addition, the relatively high rigidity of these tubes reduces their flexibility and increases the risk of collision with the tracheal wall. To address these limitations, researchers have developed a variety of flexible robotic bronchoscopic systems as alternatives to commercial bronchoscopic platforms[4]-[8]. Flexible tubes offer greater flexibility and safety compared to rigid tubes. These designs enable multiple degrees of freedom at the end of the robot. While the flexibility of the robot is beneficial for safety, it lacks the ability to withstand loads and transmit forces. The lung environment is dynamic due to the effects of breathing and cardiac movement. If the tube remains flexible at all times, it is impossible to ensure the stability and precise positioning of the distal end.

[0009] Variable stiffness catheters, capable of switching between rigidity and flexibility, represent a significant research direction in the field of medical robotics. Through innovative mechanical structure design or the application of variable stiffness functional materials, variable stiffness catheters can achieve dynamically controllable switching between rigidity and flexibility. Duan Xingguang et al. from Beijing Institute of Technology and Wang Jie et al. from Tsinghua University have proposed spring-embedded mechanical structure schemes, achieving controllable switching between catheter rigidity and flexibility by extending or compressing spring segments. [A Novel Robotic Bronchoscope System for Navigation and Biopsy of Pulmonary Lesions]; [A Novel Robotic Bronchoscope with a Spring-Based Extensible Segment for Improving Steering Ability]. While spring-based structures can significantly alter catheter stiffness, they suffer from increased structural design complexity and challenges in miniaturization. Variable stiffness materials refer to functional materials whose modulus and stiffness can be dynamically adjusted under external stimuli such as temperature. Researchers from Nanyang Technological University (NTU) and ETH Zurich (ETH Zurich) have respectively designed variable-stiffness catheters based on low-melting-point alloy materials: "Robotic Bronchoscopy System With Variable-Stiffness Catheter for Pulmonary Lesion Biopsy" and "Magnetic Continuum Device with Variable Stiffness for Minimally Invasive Surgery." Low-melting-point alloy materials are solid below their phase transition temperature, exhibiting high stiffness; above their phase transition temperature, they are liquid, exhibiting lower stiffness. The stiffness of the catheter can be controlled in real time by changing the temperature of the low-melting-point alloy material. Variable-stiffness materials are beneficial for the miniaturization of catheters, but low-melting-point alloys are highly toxic, and leakage could cause serious harm to the human body. Therefore, finding novel variable-stiffness materials with excellent biocompatibility and stable stiffness control performance is a key issue in overcoming the "rigidity-flexibility contradiction" in surgical instruments. Summary of the Invention

[0010] The purpose of this invention is to provide a multi-segment variable stiffness magnetically driven catheter and a surgical robot. Under the control of the surgical robot, the magnetically driven catheter can be inserted into small human cavities for treatment.

[0011] To achieve the above-mentioned technical objectives, the present invention adopts the following technical solution:

[0012] A multi-segment variable stiffness magnetically driven conduit includes a distal small conduit and a main conduit, wherein the distal small conduit is connected to the distal end of the main conduit; the stiffness of the distal small conduit can be controlled to change, and a certain number of annular magnets are provided on the distal small conduit, wherein the annular magnets are uniformly and discretely distributed on the distal small conduit.

[0013] A multi-segment variable stiffness magnetically driven conduit includes a distal small conduit and a main conduit, the distal small conduit being connected to the distal end of the main conduit; the distal small conduit includes a certain number of sub-segments, the sub-segments being connected end to end in sequence; each sub-segment is composed of an inner tube body and an outer tube body, the outer tube body being made of shape memory polymer, a heating coil being disposed in the outer tube body, annular magnets being disposed between adjacent sub-segments, and annular magnets being disposed at the farthest end of the distal small conduit.

[0014] Furthermore, annular magnets are provided between adjacent sub-tube segments, and annular magnets are provided at the farthest end of the distal conduit. The specific structural form is as follows: annular magnets are provided for each sub-tube segment, and the annular magnets are located at the end of the sub-tube segment. When all sub-tube segments are connected together to form a complete distal conduit, there are annular magnets between adjacent sub-tube segments, and there is also annular magnet at the farthest end of the distal conduit.

[0015] Furthermore, a temperature sensor is installed in the outer tube of the sub-tube segment.

[0016] Furthermore, the temperature sensor is linear and is arranged in a spiral shape within the outer tube of the sub-tube section.

[0017] Furthermore, the magnetically driven conduit is also equipped with a microcontroller, which is used to control the heating of the sub-tube segments based on the temperature signals of the temperature sensors in each sub-tube segment of the distal conduit, so as to control the stiffness of the sub-tube segments within the required range.

[0018] Furthermore, the outer peripheral surface of the distal small catheter is coated with hydrogel.

[0019] Furthermore, the inner tube of the sub-tube segment is made of polytetrafluoroethylene.

[0020] A surgical robot employing a magnetically driven catheter as described above.

[0021] Furthermore, the surgical robot has a robotic arm with a magnet installed at the end of the robotic arm. By controlling the movement of the robotic arm, the magnet guides the movement of the annular magnet, thereby controlling the magnetically driven conduit to change its posture.

[0022] The main advantages of the multi-segment variable stiffness magnetically driven catheter and surgical robot of the present invention compared with the prior art are as follows:

[0023] The distal small catheter in the magnetically driven catheter has its stiffness controlled by temperature control at various parts, and the posture of the distal small catheter is controlled by the magnet at the end of the surgical robot's robotic arm. Based on this mode of catheter, the outer diameter of the catheter is smaller without reducing the inner diameter of the working channel, so that it can be inserted into small human cavities, thereby creating favorable conditions for disease treatment. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the structure of a multi-segment variable stiffness magnetically driven conduit based on Embodiment 1 of the present invention;

[0025] Figure 2 This is a schematic cross-sectional view of a sub-tube segment in the magnetically driven conduit of Embodiment 1.

[0026] Figure 3 This is a schematic diagram of the structure of the variable stiffness unit in the multi-segment variable stiffness magnetically driven conduit based on Embodiment 2 of the present invention.

[0027] Figure 4 This is a schematic diagram of the magnetically driven conduit in Embodiment 2;

[0028] Figure 5 This is a diagram illustrating the catheter stiffness control technology scheme for the magnetically driven catheter in Implementation Method 2.

[0029] Figure 6 This is a schematic diagram illustrating the specific fabrication process of the magnetically driven conduit in Embodiment 2.

[0030] Figure 7 This is a detailed implementation diagram of the guide tube stiffness control of the magnetically driven guide tube in Embodiment 2;

[0031] Figure 8 This is a flowchart of the guide tube stiffness adjustment process for the magnetically driven guide tube in Implementation Method 2. Detailed Implementation

[0032] The following provides further details on specific embodiments of the present invention:

[0033] Implementation method 1:

[0034] This embodiment 1 provides a multi-segment variable stiffness magnetically driven conduit. The implementation of the magnetically driven conduit in this embodiment 1 differs from that of existing rope-driven conduits.

[0035] Specifically

[0036] See Figure 1 and Figure 2In this embodiment 1, the magnetically driven conduit is mainly composed of a distal small conduit 1 and a main conduit 2 joined together, with the joining position as shown in the figure. Figure 1 As indicated by the middle arrow A, the distal small catheter 1 is located at the distal end of the main catheter 2, and the two are connected together by hydrogel.

[0037] The distal conduit 1 is composed of a certain number of sub-tube segments 11 connected end to end in sequence. The sub-tube segments 11 have variable stiffness characteristics, thereby giving the entire distal conduit 1 variable stiffness characteristics.

[0038] See Figure 2 In this embodiment 1, the tube body of the sub-tube segment 11 is composed of two tube bodies: an inner tube body 111 and an outer tube body 112. The inner tube body 111 is made of polytetrafluoroethylene, and the outer tube body 112 is made of shape memory polymer.

[0039] The shape memory polymer exhibits the characteristic that its stiffness decreases with increasing temperature and increases with decreasing temperature. Therefore, by controlling the temperature change of the outer tube 112 of the sub-tube segment 11, the stiffness change of the sub-tube segment 11 and even the entire distal small conduit 1 can be controlled. Furthermore, it should be noted that the shape memory polymer, compared to existing low-melting-point alloy materials, has better biocompatibility, higher safety, and remains solid throughout the entire stiffness-changing process.

[0040] A conductive wire (copper wire) is installed in the outer tube body 112 of the sub-tube segment 11. The conductive wire is spirally wound around the outer circumference of the inner tube body 111, forming an electrical circuit in the outer tube body 112 of the sub-tube segment 11. The conductive wire constituting the electrical circuit essentially forms a heating coil 4, used to heat the outer tube body 112 of the sub-tube segment 11 to change its stiffness. When the electrical circuit is energized, the conductive wire (i.e., the heating coil 4) generates heat to heat the outer tube body 112. By controlling the temperature, the stiffness of the outer tube body 112 is controlled, ultimately achieving segmented control of the stiffness of the entire distal small conduit 1.

[0041] With regard to a single sub-tube segment 11, one end of the sub-tube segment 11 is the end (the end closer to the distal end of the magnetically driven conduit), and the other end of the sub-tube segment 11 is the beginning (the end closer to the proximal end of the magnetically driven conduit).

[0042] Both ends of the conductive wire of sub-segment 11 are located at the beginning of sub-segment 11, and the ends of the conductive wires of all sub-segments 11 extend to the proximal end of the magnetically driven conduit to facilitate connection to an external power source. Heating can be controlled individually for each sub-segment 11, thereby achieving the effect of "individually controlling the stiffness change of each sub-segment 11".

[0043] Each sub-tube segment 11 is provided with an annular magnet 12, which is located at the end of the sub-tube segment 11. When all sub-tube segments 11 are connected together to form a complete distal conduit 1, there are annular magnets 12 between adjacent sub-tube segments 11, and there is also an annular magnet 12 at the farthest end of the distal conduit 1, which facilitates magnetic drive control of various parts of the distal conduit 1.

[0044] A linear temperature sensor 3 is also provided in the outer tube body 112 of the sub-tube section 11. The temperature sensor 3 is spirally wound around the entire outer circumference of the inner tube body 111. The temperature sensor 3 is connected to the proximal end of the magnetically driven conduit through a signal line so as to transmit temperature signals to the outside.

[0045] The temperature sensor 3 is used to detect the temperature of the outer tube body 112 of the sub-tube segment 11. In this way, the heating temperature of the outer tube body 112 of the sub-tube segment 11 can be accurately controlled based on the temperature signal of the temperature sensor 3, thereby controlling the overall rigidity of the sub-tube segment 11 and even the distal small conduit 1.

[0046] Hydrogel is coated on the outer circumferential surface of the distal catheter 1, including the area where the distal catheter 1 connects with the main catheter 2. The function of the hydrogel is:

[0047] The hydrogel can stably connect the various sub-segments 11 of the distal catheter 1 together.

[0048] Hydrogel can improve the surface lubricity of distal catheter 1 and reduce the friction between distal catheter 1 and the body cavity.

[0049] Hydrogel can isolate the heat generated by heating the distal small catheter 1 from the transmission of heat to the human body cavity, thus avoiding harm to the human body.

[0050] The magnetically driven conduit of Embodiment 1 is used and operates as follows:

[0051] A surgical robot is configured, which has a robotic arm with a permanent magnet installed at the end of the robotic arm. During the establishment of a channel in the patient's body using the magnetically driven catheter of Embodiment 1, when it is necessary to control the attitude of the distal small catheter 1 at the distal end of the magnetically driven catheter (e.g., turning), the stiffness of the distal small catheter 1 is reduced by electric heating. Then, the robotic arm is controlled to move towards the distal end of the magnetically driven catheter. The permanent magnet at the end of the robotic arm guides the annular magnet 12 on the distal small catheter 1 to move. The annular magnet 12 begins to displace under the attraction of the permanent magnet, thereby causing the distal small catheter 1 to change its attitude (i.e., achieve turning). After heating is stopped, the stiffness of the distal small catheter 1 increases, thus forming support.

[0052] It should be noted that in magnetically driven conduits,

[0053] The main guide tube 2 has high rigidity, which ensures the support stability of the entire magnetic drive guide tube.

[0054] The stiffness of the distal small catheter 1 is controllable, thus allowing for adjustments as needed.

[0055] "Reduce stiffness to improve the mobility of the distal end of the magnetically driven conduit."

[0056] or

[0057] "Strengthen stiffness to improve the support stability of the distal end of the magnetically driven conduit."

[0058] In addition, a microcontroller is also provided for the magnetically driven conduit in this embodiment 1. The function of the microcontroller is to control the heating of the sub-tube segments 11 based on the temperature signals of the temperature sensors 3 in each sub-tube segment 11 in the distal small conduit 1, thereby controlling the temperature of the sub-tube segments 11 within a set range, and thus controlling the stiffness of the sub-tube segments 11 within the required range.

[0059] Specifically

[0060] Temperature sensors 3 in each sub-segment 11 transmit temperature values ​​to the microcontroller. The microcontroller uses a PID algorithm to adjust the heating power based on the target temperature. Heating stops once the surface temperature of the sub-segment 11 reaches the target temperature, and resumes heating when the surface temperature drops below the target temperature. The multi-segment design allows each segment to be heated or cooled independently, resulting in differentiated stiffness configurations. In clinical operations, flexible or rigid states can be flexibly switched according to the bending and support requirements of the access pathway, enabling diverse operational strategies.

[0061] The surgical robot's robotic arm is a 6-DOF (DoF) robotic arm with a permanent magnet mounted at its end. The robotic arm can be remotely controlled using a handle. By adjusting the position of the permanent magnet and its distance from the catheter, the flexible catheter segment can bend and adjust to conform to the magnetic field, while the high-stiffness segment remains stable. This achieves precise control with multi-segment coordination and independent segmental response. Compared to traditional single-segment magnetic drive methods, this method can achieve higher precision in attitude maintenance and path following in complex bifurcated and high-curvature paths, significantly improving the flexibility and safety of deep lung access navigation.

[0062] It should be noted that, as Figure 1 As shown, in this embodiment 1, the distal small catheter 1 is composed of two sub-tube segments 11 connected together. In other embodiments, the specific number of sub-tube segments 11 in the distal small catheter 1 can be set according to actual needs, and the present invention does not limit this.

[0063] The main advantage of the magnetically driven conduit in Embodiment 1 is that:

[0064] 1) The magnetically driven catheter of this embodiment 1 does not use the traditional "rope-driven" method for attitude control, but rather a "magnetic-driven" method. Specifically, annular magnets 12 are evenly and discretely arranged on the distal small catheter 1. The stiffness of various parts of the distal small catheter 1 can be changed through temperature control. For example, heating reduces the stiffness of the distal small catheter 1, and then the magnet at the end of the surgical robot's robotic arm controls the bending and turning of the distal small catheter 1. Then, heating is stopped, and the stiffness of the distal small catheter 1 increases, providing stronger support. Compared to existing rope-driven catheters, this is a completely new catheter structure and attitude control mode. Based on this mode, the catheter has a smaller outer diameter without reducing the inner diameter of the working channel, allowing it to extend into smaller human cavities, thus creating favorable conditions for disease treatment.

[0065] Furthermore, the magnetically driven conduit of Embodiment 1 has other advantages, as follows:

[0066] 2) Compared with existing purely rigid or purely flexible catheters, the magnetically driven catheter of this embodiment 1 can adjust its stiffness according to the doctor's operational needs, which can better meet clinical needs. This is something that existing catheters cannot achieve.

[0067] Implementation Method 2:

[0068] Embodiment 2 provides a magnetically driven conduit that embodies the original concept of the present invention, as detailed below:

[0069] Currently, lung cancer is a malignant tumor originating from the bronchial mucosa or lung glands, posing a serious threat to human health and survival. According to the latest statistics from the World Health Organization, lung cancer ranks second in incidence and first in mortality among all cancers worldwide [1]. In the early stages, lung cancer usually presents as small lung nodules. Therefore, accurate detection of these nodules is crucial for improving patient survival. Traditional diagnostic methods, including chest X-ray, computed tomography (CT) scan, and percutaneous biopsy, have limitations such as insufficient accuracy, high radiation exposure, and potential complication risks [2]. Bronchial biopsy provides a promising minimally invasive method for the early diagnosis of lung cancer. In clinical practice, bronchial biopsy is usually performed manually, which places high demands on the operator's experience and physical strength. These requirements hinder its widespread application. In recent years, robotic bronchoscopy systems have attracted great attention from the clinical and research communities. Compared with manual operation, which may lead to muscle fatigue and decreased attention, robotic platforms have higher motion accuracy and stability.

[0070] To date, three bronchoscopic robotic platforms have been approved by the U.S. Food and Drug Administration (FDA) (Monarch, Ion, and Galaxy)[3]. These bronchoscopic robots have demonstrated effectiveness in clinical practice. Their diagnostic rates and complication control are significantly better than traditional techniques. However, the average outer diameter of these three bronchoscopic robots is typically greater than 3.5 mm, which limits their ability to access distal airways (such as subsegmental bronchi) with a diameter of approximately 3.25 mm. In addition, the relatively high rigidity of these tubes reduces their flexibility and increases the risk of collision with the tracheal wall. To address these limitations, researchers have developed a variety of flexible robotic bronchoscopic systems as alternatives to commercial bronchoscopic platforms[4]-[8]. Flexible tubes offer greater flexibility and safety compared to rigid tubes. These designs enable multiple degrees of freedom at the end of the robot. While the flexibility of the robot is beneficial for safety, it lacks the ability to withstand loads and transmit forces. The lung environment is dynamic due to the effects of breathing and cardiac movement. If the tube remains flexible at all times, it is impossible to ensure the stability and precise positioning of the distal end.

[0071] See Figures 3 to 8 This embodiment 2 provides a multi-segment variable stiffness magnetically driven catheter, aiming to solve the problems of existing bronchoscopic catheters having large diameters, fixed stiffness, and the inability to simultaneously achieve flexible navigation and rigid positioning. This catheter, by employing a multi-segment variable stiffness design based on shape memory polymers (SMP) and combined with a precise temperature control system, achieves flexible adjustment and stable support of the distal catheter, meeting the clinical needs for navigation and precise positioning in complex pulmonary pathways.

[0072] The catheter has an outer diameter of approximately 2 mm and an inner diameter of approximately 1 mm. The outer diameter is small enough to meet the passage requirements of terminal branches of multiple bronchi, while the inner diameter is large enough to accommodate various examination tools such as cameras and biopsy forceps. It consists of multiple variable stiffness units connected sequentially to form a multi-segment structure. The length of a single variable stiffness unit is 35 mm, and the length of the high stiffness unit is 800 mm. The overall length is sufficient to meet the needs of lung examination.

[0073] The catheter material: The body of the variable stiffness unit can be made from various types of shape memory polymers, including but not limited to photocurable and thermocurable polymers. Shape memory polymers have good biocompatibility and a significant range of stiffness control. Shape memory polymers exhibit temperature-dependent phase transition characteristics: when the temperature is below the glass transition temperature, the material is in a high-stiffness glassy state, suitable for stable positioning and support; when the temperature is above the glass transition temperature, the material transforms into a low-stiffness rubbery state, making the catheter flexible and capable of navigating to complex branches of the lungs. From the glassy state to the rubbery state, the stiffness of the catheter undergoes a significant temperature-related change. A 1mm inner diameter, 0.025mm thick polytetrafluoroethylene (PTFE) inner tube is embedded inside the catheter to ensure the stability and low friction of the working channel and to provide thermal insulation.

[0074] Catheter stiffness control: A double-helix copper wire is evenly embedded along the axial direction of the PTFE tube of the catheter body. Joule heating is generated by an electric current to heat the NOA86 catheter body. Before coating the catheter surface with fluorinated hydrogel, a temperature sensor (accuracy ±0.5°C) is wound along the axial direction to monitor the catheter surface temperature in real time. The temperature sensor of each variable stiffness unit transmits the temperature value to a microcontroller. The microcontroller uses a PID algorithm to adjust the heating power according to the target temperature. Heating stops when the catheter surface temperature reaches the target temperature and resumes when the surface temperature drops below the target temperature. The multi-segment catheter design allows each segment to be heated or cooled independently, creating differentiated stiffness configurations. In clinical operation, flexible switching between flexible and rigid states can be achieved according to the bending and support requirements of the access pathway, enabling diverse operational strategies.

[0075] Multi-segment conduit design: Variable stiffness conduits can be combined with any number of variable stiffness units and high stiffness units. During assembly, a stainless steel rod is placed in the central working channel to ensure coaxiality. A hydrogel coating is then applied to the outermost layer of the conduit. The hydrogel not only stably connects the segments but also improves surface lubrication, reduces friction, and isolates temperature conduction during heating.

[0076] Magnetic control of the catheter: To simultaneously ensure the miniaturization and flexibility of the catheter, each variable stiffness unit is equipped with a ring-shaped N52 magnet with the same inner and outer diameters as the catheter. Under the influence of an external magnetic field, contactless navigation is achieved. The external magnetic field can be a single robotic arm with a permanent magnet, or multiple electromagnetic coils. In its flexible state, the catheter can bend arbitrarily in the external magnetic field, while in its rigid state, it maintains a relatively unchanged posture. Compared to a single-segment catheter, multiple-segment catheters allow for control of the stiffness of different segments under the same magnetic field, achieving different shapes. When multiple segments are in a rubbery state, each segment can respond independently to the external magnetic field, enabling precise navigation along complex paths. When multiple segments are in a glassy state, stable posture maintenance is achieved. The configuration of multiple-segment catheters is beneficial for movement and posture maintenance in complex pulmonary bronchial environments.

[0077] The advantages of the magnetically driven conduit in this embodiment 2 are:

[0078] (1) The existing catheters have a large outer diameter and a small inner diameter, making it difficult to penetrate into the subsegment and more distal bronchus, and also difficult to accommodate tools such as cameras and biopsy forceps at the same time.

[0079] Improvements to the magnetically driven catheter in Embodiment 2: The catheter has an outer diameter of 2mm and an inner diameter of 1mm; it features a built-in PTFE working channel and a multi-segment structure with multiple variable stiffness sections plus one high-stiffness section. The smaller outer diameter results in higher throughput and reduced risk of compression and collision within the endotracheal cavity; the 1mm inner diameter enhances tool compatibility, supporting various applications such as biopsy and imaging; the multi-segment structure ensures stability at the proximal end and flexibility at the distal end, maintaining axial support even when entering deep bronchi.

[0080] (2) The existing catheters have fixed rigidity, making it difficult to balance "flexible navigation" and "rigid positioning".

[0081] The improvements of the magnetically driven conduit in Embodiment 2 are as follows: The variable stiffness unit uses a shape memory polymer, which can achieve stiffness changes on the order of approximately 10³ according to temperature variations. The conduit's rubber state conforms to complex curvatures, while its glassy state provides high load-bearing / buckling resistance. Multiple variable stiffness units are independently temperature-controlled and work in conjunction with high-stiffness sections. Differentiated stiffness configurations at different sections achieve "local flexibility and overall stability." At bifurcation / sharp bends, only the target section can be softened, reducing tip rebound and tailing, and improving path-following accuracy. "Intra-segment compliance + inter-segment support" reduces cumulative deformation errors and improves repeatability.

[0082] (3) The existing catheters have a large friction between the exposed polymer surface and the tissue, which is easy to irritate.

[0083] The improvements of the magnetically driven catheter in this embodiment 2 are as follows: the catheter is coated with a hydrogel coating and insulated with a PTFE inner tube for heat insulation and friction reduction. The hydrogel provides a hydrophilic lubricating interface, significantly reducing friction and tensile forces, which is beneficial for turning in narrow tubes; the coating and PTFE work together to form a temperature buffer, reducing thermal stimulation to surrounding tissues; it also has better tissue compatibility, reducing the probability of potential mucosal irritation and micro-damage.

[0084] The following describes the manufacturing process of variable stiffness elements:

[0085] The manufacturing process of the variable stiffness unit utilizes the UV-curing properties of shape memory polymers and requires a transparent mold to achieve a complete photopolymerization reaction. Polydimethylsiloxane (PDMS) was chosen as the mold material because of its optical transparency in the UV band and its mechanical flexibility for easy demolding. First, a PDMS mold with a central negative cavity is prepared by placing a steel rod and a PTFE tube. Then, PDMS is poured into the mold, degassed, and thermocured. One side of the cured PDMS mold is cut to remove the steel rod, thus forming the negative cavity. A PTFE tube wound with copper wire is fitted onto the steel rod and placed inside the mold. Shape memory polymer is injected into the cavity until it is completely filled using a syringe, followed by 30 minutes of UV curing (395 nm). After the shape memory polymer has cured, the tube is removed from the PDMS mold, and then the steel rod is pulled out to expose the central cavity. Each variable stiffness unit is equipped with a ring magnet at its distal end for magnetic actuation and a surface temperature sensor for temperature monitoring.

[0086] The entire conduit consists of multiple variable stiffness units and a high-stiffness PEBAX unit. The variable stiffness units provide flexibility and distal support, while the PEBAX unit ensures overall structural stability. During assembly, the multiple variable stiffness units are first plasma-treated. They are then connected to the PEBAX tube for hydrogel coating. The hydrogel layer is encapsulated using an impregnation method. The thickness of the hydrogel can be controlled by the number of impregnation operations.

[0087] The stiffness of the magnetically driven conduit is affected by temperature. Therefore, precise stiffness control can be achieved by adjusting its temperature. Each variable stiffness unit is equipped with a dedicated surface temperature sensor, which provides direct feedback with an accuracy of ±0.5°C, enabling accurate and real-time monitoring. Figure 5This illustrates a closed-loop heating and temperature control scheme. In this design, copper wires embedded in the conduit are connected to the power supply via a MOSFET switch, while a temperature sensor continuously feeds back measured values ​​to the microcontroller via a temperature transmitter. Once the target temperature is reached, the MOSFET switch is disabled to stop heating, and the conduit cools naturally. To avoid frequent switching around the target value, heating is reactivated when the temperature drops to 4°C below the target temperature. During heating, a PID controller embedded within the microcontroller adjusts the heating power applied to the conduit to ensure stable and accurate temperature control.

[0088] The magnetic drive of the duct is achieved by a permanent magnet mounted at the end of a 6-DOF robotic arm, which can be remotely controlled using a handle. By adjusting the position of the permanent magnet and its distance from the duct, the flexible duct segment can bend and adjust in accordance with the magnetic field, while the high-stiffness segment remains stably supported. This enables precise control with multi-segment coordination and independent segmental response. Compared with the traditional single-segment magnetic drive method, it can achieve higher precision in attitude maintenance and path following in complex bifurcations and high curvature paths, significantly improving the flexibility and safety of deep lung access navigation.

[0089] It should be noted that in this embodiment 2, the variable stiffness unit is equivalent to the sub-pipe segment in embodiment 1, and the high stiffness unit is equivalent to the main pipe in embodiment 1.

[0090] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Therefore, any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A multi-segment variable stiffness magnetically driven conduit, characterized in that: The magnetically driven conduit includes a distal small conduit (1) and a main conduit (2), wherein the distal small conduit (1) is connected to the distal end of the main conduit (2); The distal conduit (1) can controllably change its stiffness. A certain number of annular magnets (12) are provided on the distal conduit (1), and the annular magnets (12) are evenly and discretely distributed on the distal conduit (1).

2. A multi-segment variable stiffness magnetically driven conduit, characterized in that: The magnetically driven conduit includes a distal small conduit (1) and a main conduit (2), wherein the distal small conduit (1) is connected to the distal end of the main conduit (2); The distal catheter (1) includes a certain number of sub-tube segments (11), which are connected end to end in sequence; The sub-tube segment (11) is composed of an inner tube body (111) and an outer tube body (112). The outer tube body (112) is made of shape memory polymer. A heating coil (4) is provided in the outer tube body (112). A ring magnet (12) is provided between adjacent sub-tube segments (11). A ring magnet (12) is provided at the farthest end of the distal small conduit (1).

3. The multi-segment variable stiffness magnetically driven conduit according to claim 2, characterized in that: A ring magnet (12) is provided between adjacent sub-tube segments (11), and a ring magnet (12) is provided at the farthest end of the distal small conduit (1). The specific implementation structure is as follows: a ring magnet (12) is provided for each sub-tube segment (11), and the ring magnet (12) is located at the end of the sub-tube segment (11). When all sub-tube segments (11) are connected together to form a complete distal small conduit (1), there is a ring magnet (12) between adjacent sub-tube segments (11), and there is also a ring magnet (12) at the farthest end of the distal small conduit (1).

4. The multi-segment variable stiffness magnetically driven conduit according to claim 2, characterized in that: A temperature sensor (3) is installed in the outer tube body (112) of the sub-tube section (11).

5. The multi-segment variable stiffness magnetically driven conduit according to claim 4, characterized in that: The temperature sensor (3) is linear and is arranged in a spiral shape in the outer tube body (112) of the sub-tube section (11).

6. The multi-segment variable stiffness magnetically driven conduit according to claim 4, characterized in that: The magnetically driven conduit is also equipped with a microcontroller, which is used to control the heating of the sub-tube segments (11) based on the temperature signals of the temperature sensors (3) in each sub-tube segment (11) in the distal small conduit (1), so as to control the stiffness of the sub-tube segments (11) within the required range.

7. The multi-segment variable stiffness magnetically driven conduit according to claim 2, characterized in that: The outer peripheral surface of the distal small catheter (1) is coated with hydrogel.

8. The multi-segment variable stiffness magnetically driven conduit according to claim 2, characterized in that: The inner tube (111) of the sub-tube section (11) is made of polytetrafluoroethylene.

9. A surgical robot, characterized in that: The surgical robot employs the magnetically driven catheter as described in claim 1 or 2.

10. The surgical robot according to claim 9, characterized in that: The surgical robot has a robotic arm with a magnet installed at the end of the robotic arm. By controlling the movement of the robotic arm, the magnet guides the movement of the annular magnet (12) to control the magnetically driven conduit to change its posture.

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