Fiber bragg grating force sensor for cardiac ablation catheter

Abstract

The invention relates to the field of medical instruments, and discloses a fiber bragg grating force sensor for a cardiac ablation catheter, the fiber bragg grating force sensor comprises a sensor main body and three optical fibers engraved with fiber bragg gratings, and the optical fibers engraved with the fiber bragg gratings are installed on the inner wall of the sensor main body; the sensor body comprises an upper fixing end, an elastic body, a lower fixing end and a sensor base, the right side of the upper fixing end is located on the left side of the elastic body, the right side of the elastic body is located on the left side of the lower fixing end, and the right side of the lower fixing end is located on the left side of the sensor base; the upper fixing end and the lower fixing end are each provided with a plurality of grooves. By means of the high-precision measuring capacity of the fiber grating sensor, three-dimensional force information of the tail end of the cardiac ablation catheter can be detected in real time, force feedback when the cardiac ablation catheter makes contact with cardiac tissue is provided for a doctor, tissue damage caused by too large force is effectively reduced, the accuracy of an operation is improved, and the doctor is helped to complete ablation operation more safely and accurately.

Description

Technical Field

[0001] The present invention relates to the field of medical devices, and in particular to a fiber grating force sensor for a cardiac ablation catheter. Background Art

[0002] At present, the mortality rate of cardiovascular disease (CVD) in my country still ranks first, higher than that of tumors and other diseases, seriously affecting people's lives and health. Arrhythmia is one of the common clinical manifestations of CVD, which causes abnormal heart rate due to the origin and conduction disorders in cardiac activity. Drug treatment has limited effect, many side effects and a long treatment cycle. Radiofrequency ablation surgery via cardiac catheter is the main treatment method. The electrode catheter is delivered to the key part through the vein or artery, and the radiofrequency current is released to cause necrosis of the adjacent tissue to prevent rapid arrhythmia.

[0003] In traditional ablation surgery, the doctor needs to rely on his own experience and the two-dimensional image of the X-ray machine to send the catheter to the target point in the heart. The lack of feedback on the contact force with the tissue will reduce the doctor's flexibility during the operation and easily cause damage to the patient's tissues and organs. In severe cases, it may even threaten the patient's life. In order to enable the ablation catheter to better perform ablation treatment on the lesion area during the operation, it is necessary to sense the contact force at the end of the ablation catheter, thereby improving the efficiency and safety of the operation. Therefore, how to design a high-precision, high-sensitivity miniature force sensor for use in ablation catheters is a technical problem that technicians in this field urgently need to solve. Summary of the invention

[0004] In view of the deficiencies in the prior art, the present invention provides a fiber grating force sensor for a cardiac ablation catheter, which solves the problem that in traditional ablation surgery, the operating doctor needs to rely on his own experience and the two-dimensional image of the X-ray machine to send the catheter to the target point in the heart, and the lack of feedback on the contact force with the tissue reduces the flexibility of the doctor's operation during the operation.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A fiber grating force sensor for a cardiac ablation catheter comprises a sensor body and three optical fibers engraved with fiber gratings, wherein the optical fibers engraved with fiber gratings are installed on the inner wall of the sensor body;

[0006] The sensor body comprises an upper fixed end, an elastic body, a lower fixed end and a sensor base, wherein the right side of the upper fixed end is located on the left side of the elastic body, the right side of the elastic body is located on the left side of the lower fixed end, and the right side of the lower fixed end is located on the left side of the sensor base;

[0007] The upper fixed end and the lower fixed end are both provided with a plurality of grooves, the grooves are distributed at fixed angle intervals on the circumference of the sensor body, and the two ends of the optical fiber engraved with the fiber grating are fixed in the grooves.

[0008] Preferably, the elastic body is composed of multiple layers of parallel beam grooves for reducing the axial stiffness of the sensor, and the three optical fibers engraved with fiber gratings include optical fiber one, optical fiber two and optical fiber three.

[0009] Preferably, the three optical fibers engraved with fiber gratings are arranged around the inner wall of the sensor body at intervals of 120°, fiber 1 is engraved with fiber grating 1, fiber 2 is engraved with fiber grating 4, and fiber 3 is engraved with fiber grating 2 and fiber grating 3, for measuring lateral force and axial force.

[0010] Preferably, the fiber grating on the tail of one of the three optical fibers engraved with fiber gratings and the optical fiber engraved with dual fiber gratings is fixed at only one end and is located in the sensor base without being subjected to stress, so as to compensate for changes in ambient temperature.

[0011] Preferably, the fiber grating is fixed in the groove by a medical adhesive, and a certain pre-tension is applied.

[0012] Preferably, the material of the sensor includes resin, silica optical fiber and ethyl cyanoacrylate glue, wherein the resin is used for the sensor body, the silica optical fiber is used for the fiber grating, and the glue is used to fix the fiber grating.

[0013] Preferably, a hollow channel is provided in the middle of the sensor, and the sensor base is a hollow cylinder. The hollow channel is used for conveying contrast agent and arranging cables to control ablation electrodes.

[0014] The present invention provides a fiber grating force sensor for a cardiac ablation catheter, which has the following beneficial effects:

[0015] 1. The present invention can detect the three-dimensional force information at the end of the cardiac ablation catheter in real time through the high-precision measurement capability of the fiber grating sensor, which provides doctors with force feedback when in contact with cardiac tissue, effectively reduces tissue damage caused by excessive force, improves the accuracy of the operation, and helps doctors complete the ablation operation more safely and accurately.

[0016] 2. The present invention uses a three-dimensional force sensing function to enable doctors to clearly understand the contact force between the ablation catheter and the tissue, thereby avoiding damage caused by excessive force, reducing the risk of surgery, and reducing the probability of postoperative complications.

[0017] 3. The fiber optic sensor of the present invention has the characteristic of anti-electromagnetic interference, which can effectively avoid the interference of electromagnetic signals in complex surgical environments and improve the stability and reliability of measurements. Traditional electrical sensors are easily interfered by electromagnetic equipment (such as ablation power supply and imaging equipment) in surgical environments, while sensors based on fiber gratings can maintain accurate and stable measurements in complex surgical environments.

[0018] 4. The fiber grating sensor of the present invention is small in size, light in weight, has good biocompatibility, and is suitable for integration with cardiac ablation catheters. The non-toxicity and corrosion resistance of the fiber material ensure that it will not produce any adverse reactions to the human body during surgery, and can tolerate the internal environment, ensuring the safety and reliability of the surgery. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a schematic diagram of the sensor structure of the present invention;

[0020] Figure 2 It is a top view of the sensor of the present invention.

[0021] Among them, 1. upper fixed end; 2. elastomer; 3. lower fixed end; 4. sensor base; 5. optical fiber 1; 6. optical fiber 2; 7. optical fiber 3; 8. optical fiber grating 1; 9. optical fiber grating 2; 10. optical fiber grating 3; 11. optical fiber grating 4; 12. hollow channel; 13. glue. DETAILED DESCRIPTION

[0022] The technical solution of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention.

[0023] Please see attached Figure 1 - Attachment Figure 2 , an embodiment of the present invention provides a fiber Bragg grating force sensor for a cardiac ablation catheter, comprising a sensor body and three optical fibers engraved with fiber Bragg gratings, wherein the optical fibers engraved with fiber Bragg gratings are installed on the inner wall of the sensor body;

[0024] The sensor body includes an upper fixed end 1, an elastic body 2, a lower fixed end 3 and a sensor base 4, the right side of the upper fixed end 1 is located on the left side of the elastic body 2, the right side of the elastic body 2 is located on the left side of the lower fixed end 3, and the right side of the lower fixed end 3 is located on the left side of the sensor base 4;

[0025] The upper fixed end 1 and the lower fixed end 3 are both provided with a plurality of grooves, which are distributed around the sensor body at fixed angle intervals, and the two ends of the optical fiber engraved with the fiber grating are fixed in the grooves;

[0026] The three optical fibers engraved with fiber gratings include optical fiber 1 5 , optical fiber 2 6 , and optical fiber 3 7 .

[0027] Specifically, Figure 1 As shown. The sensor body includes an upper fixed end 1, an elastic body 2, a lower fixed end 3 and a sensor base 4. The upper fixed end 1 and the lower fixed end 3 are each provided with three grooves, and the grooves are distributed on the circumference of the sensor body at a fixed angle interval, and the two ends of the fiber grating 1 8, the fiber grating 2 9 and the fiber grating 4 11 are fixed in the grooves. The grooves at the upper and lower fixed ends can help position the optical fiber and improve the coaxiality between the fiber grating 1 8, the fiber grating 2 9 and the fiber grating 4 11 and the sensor body. In addition, the grooves can also reduce the axial stiffness of the tube, thereby improving the sensitivity of the three-degree-of-freedom force sensor to the axial force. The elastic body 2 is composed of multiple layers of parallel beam grooves, and the sensor base is a hollow cylinder. Three optical fibers are arranged around the inner wall of the sensor body at intervals of 120°, two of which are respectively engraved with a fiber grating 1 8 and a fiber grating 4 11 sensor, and the other optical fiber is engraved with a fiber grating 2 9 and a fiber grating 3 10 sensor, as shown Figure 1 As shown. FBG 1 8, FBG 2 9 and FBG 4 11 are respectively composed of FBG sensors with the same central wavelength of each optical fiber, located in the elastic body 2, and used to measure lateral force and axial force. In order to enable FBG 1 8, FBG 2 9 and FBG 4 11 to effectively capture the strain of the main body, only medical adhesive is used to fix the two ends of the sensors including FBG 1 8, FBG 2 9 and FBG 4 11 in the groove of the fixed end, and a certain pre-tension is applied to the optical fiber. FBG 3 10 is a FBG on the tail of one of the optical fibers, only one end is fixed, located in the sensor base 4, not subject to stress, used for temperature compensation, and the central wavelength is different from FBG 2 9. Due to the performance limitations of the manufacturing equipment and the requirements of the sensor components, the grating length of all FBG 1 8, FBG 2 9, FBG 3 10 and FBG 4 11 sensors is designed to be 4 mm, and the grating interval between two FBG 2 9 and FBG 3 10 sensors along the same optical fiber is 6 mm.

[0028] The elastic body 2 is composed of multiple layers of parallel beam grooves and is used to reduce the axial stiffness of the sensor.

[0029] Specifically, the role of the elastic body: The elastic body is the main part of the entire sensor system for transmitting external applied force. In order to improve the sensitivity to small forces, the elastic body is designed as a multi-layer parallel beam groove structure. Such a structure can make the elastic body produce greater deformation when the sensor is subjected to axial force or lateral force, so that the strain in the fiber Bragg grating is also more significant, which is convenient for measurement.

[0030] Advantages of multi-layer parallel beam groove: The multi-layer structure design can reduce the rigidity of the structure, thereby increasing the efficiency of force transmission and improving the sensor's response to external tiny forces. Through this design, it can be ensured that during the measurement process, the deformation of the elastic body and the optical fiber is large enough so that the change of the fiber Bragg grating reflection wavelength is more obvious, thereby improving the measurement accuracy.

[0031] Three optical fibers engraved with fiber Bragg gratings are arranged around the inner wall of the sensor body at intervals of 120°. Fiber 1 5 is engraved with fiber Bragg grating 1 8, fiber 2 6 is engraved with fiber Bragg grating 4 11, and fiber 3 7 is engraved with fiber Bragg grating 2 9 and fiber Bragg 3 10, which are used to measure lateral force and axial force.

[0032] Specifically, the three optical fibers in the sensor are arranged around the inner wall of the sensor body at intervals of 120 degrees. The reason for this design is to enable the sensor to measure three-dimensional forces, including the perception of lateral and axial forces.

[0033] Necessity of fiber arrangement: Three optical fibers are evenly distributed around the sensor body at an angle of 120°, ensuring that each fiber can measure the force applied by the outside world. The even distribution of these optical fibers makes it possible to obtain the magnitude and direction of the three-dimensional force on the end of the catheter through a demodulation algorithm based on the change in the reflected wavelength of each optical fiber.

[0034] The fiber grating on the tail of one of the three optical fibers engraved with fiber gratings is fixed at only one end and is located in the sensor base 4 without being subjected to stress, so as to compensate for the change of ambient temperature.

[0035] Specifically, the importance of temperature compensation: Fiber Bragg gratings are not only sensitive to strain, but also to temperature changes. Therefore, during the measurement process, temperature changes will affect the reflection wavelength of the fiber Bragg grating, thereby interfering with the measurement results. In order to eliminate this interference, temperature compensation must be performed.

[0036] Design of compensation grating: Fiber Bragg Grating 4 10 is set in the sensor base, which is not subject to stress and is only affected by the ambient temperature. Therefore, by monitoring the wavelength change of fiber Bragg Grating 4 10, the change of ambient temperature can be obtained and used to correct the wavelength change of other force measuring gratings. This design can effectively eliminate the influence of temperature and make the measurement results more accurate.

[0037] The fiber Bragg grating is fixed in the groove by medical adhesive and a certain pre-tension is applied.

[0038] Specifically, adhesive fixation: The fiber Bragg grating is fixed in the groove of the sensor, and it must be firmly connected to the sensor body. The reason for using medical adhesive for fixation is that this adhesive is biocompatible, non-toxic and has good adhesion, which can ensure that the optical fiber will not fall off or loosen during the operation, affecting the measurement accuracy.

[0039] The role of pre-tension: When installing the optical fiber, it is necessary to apply appropriate pre-tension to the optical fiber to improve the sensitivity of the fiber Bragg grating. When the external force acts on the optical fiber, the pre-tension can make the optical fiber produce strain faster and increase the measurement sensitivity. This is especially important for detecting small force changes, which can improve the strain response speed and measurement accuracy of the fiber Bragg grating.

[0040] The materials of the sensor include resin, silica optical fiber and ethyl cyanoacrylate glue 13, wherein the resin is used for the sensor body, the silica optical fiber is used for the fiber grating, and the glue 13 is used to fix the fiber grating.

[0041] Specifically, resin material: the sensor body and the elastomer are made of resin material. The resin has good elasticity and low rigidity, and is suitable as the material of the sensor body so that it can generate sufficient deformation when subjected to external force, thereby transmitting force to the optical fiber.

[0042] Silica optical fiber: Optical fiber is made of silica material, which has a high refractive index and good mechanical strength. It can effectively transmit optical signals and is sensitive to strain and temperature changes. It is suitable for FBG sensor applications.

[0043] Ethyl cyanoacrylate glue: The glue is used to fix the fiber grating. Its advantages are good adhesion, non-toxicity and biocompatibility in the medical field, ensuring safety in the surgical environment.

[0044] A hollow channel 12 is provided in the middle of the sensor. The sensor base 4 is a hollow cylinder. The hollow channel 12 is used for conveying contrast agents and arranging cables to control ablation electrodes.

[0045] Specifically, the hollow channel design: the sensor base adopts a hollow cylindrical design with a channel inside. This design allows the delivery pipeline of the contrast agent and the control cable of the ablation electrode to be arranged inside the catheter at the same time, making the ablation catheter multifunctional, which can not only measure force, but also perform contrast imaging and electrode control during surgery.

[0046] Advantages during surgery: In cardiac ablation surgery, contrast agent delivery at the end of the catheter is crucial for intraoperative positioning and monitoring. At the same time, the arrangement of ablation electrodes can directly affect the effect of the surgery. Therefore, through the hollow design, the sensor can be integrated with these functions, which will neither increase the size and weight of the catheter nor affect the flexibility of the ablation surgery, greatly improving the efficiency and safety of the surgery.

[0047] Finite element analysis was performed using ANSYS Workbench (ANSYS, Inc, Pennsylvania, US). The parameters of the basic structure are shown in Table 1. The tail of the sensor was fixed during the simulation. Since the simulation process of the lateral force is similar to that of the axial force, only the results of the simulated axial force are given. Considering the complex situation of the ablation catheter during the operation, the simulation was performed under a force load of 2N. The overall structure of the sensor remained stable, and the internal optical fiber produced obvious compressive strain near the elastic body, but no structural damage occurred.

[0048] Table 1 Sensor structure parameters

[0049] part Material Young's modulus(GPa) Poisson's ratio <![CDATA[Density (kg / m 3 )]]> Basic structure Resin 2.51 0.41 1160 optical fiber Silicon dioxide 72 0.17 2500 glue Ethyl cyanoacrylate 3.40 0.35 1060

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A fiber Bragg grating force sensor for a cardiac ablation catheter, comprising a sensor body and three optical fibers engraved with fiber Bragg gratings, characterized in that: The optical fiber engraved with the fiber grating is installed on the inner wall of the sensor body; The sensor body comprises an upper fixed end (1), an elastic body (2), a lower fixed end (3) and a sensor base (4), wherein the right side of the upper fixed end (1) is located on the left side of the elastic body (2), the right side of the elastic body (2) is located on the left side of the lower fixed end (3), and the right side of the lower fixed end (3) is located on the left side of the sensor base (4); The upper fixed end (1) and the lower fixed end (3) are both provided with a plurality of grooves, the grooves being distributed at fixed angle intervals on the circumference of the sensor body, and the two ends of the optical fiber engraved with the fiber grating are fixed in the grooves.

2. The fiber grating force sensor for cardiac ablation catheter according to claim 1, characterized in that: The elastic body (2) is composed of multiple layers of parallel beam grooves and is used to reduce the axial rigidity of the sensor. The three optical fibers engraved with fiber gratings include optical fiber one (5), optical fiber two (6) and optical fiber three (7).

3. The fiber grating force sensor for cardiac ablation catheter according to claim 2, characterized in that: The three optical fibers engraved with fiber gratings are arranged around the inner wall of the sensor body at intervals of 120°, the optical fiber one (5) is engraved with fiber grating one (8), the optical fiber two (6) is engraved with fiber grating four (11), and the optical fiber three (7) is engraved with fiber grating two (9) and fiber grating three (10), and are used to measure lateral force and axial force.

4. The fiber grating force sensor for cardiac ablation catheter according to claim 1, characterized in that: The fiber grating on the tail of one of the three optical fibers engraved with fiber gratings and engraved with dual fiber gratings is fixed at only one end and is located in the sensor base (4) without being subjected to stress, and is used to compensate for changes in ambient temperature.

5. The fiber grating force sensor for cardiac ablation catheter according to claim 1, characterized in that: The optical fiber grating is fixed in the groove by a medical adhesive and a certain pre-tension is applied.

6. The fiber grating force sensor for cardiac ablation catheter according to claim 1, characterized in that: The materials of the sensor include resin, silica optical fiber and ethyl cyanoacrylate glue (13), wherein the resin is used for the sensor body, the silica optical fiber is used for the optical fiber grating, and the glue (13) is used to fix the optical fiber grating.

7. The fiber grating force sensor for cardiac ablation catheter according to claim 1, characterized in that: A hollow channel (12) is provided in the middle of the sensor; the sensor base (4) is a hollow cylinder; the hollow channel (12) is used for conveying contrast agent and arranging cables to control ablation electrodes.

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