Optical fiber three-dimensional force sensing calibration platform of intrusive guide wire tip

Abstract

The invention discloses an optical fiber three-dimensional force sensing calibration platform of an intrusive guide wire tip. The device is composed of an interventional medical guide wire, a four-core optical fiber, a single-mode optical fiber, a thermal diffusion coupler, a plurality of fiber Bragg gratings (FBGs), a pull and push dynamometer, a fixed supporting rod, an electric control displacement table, a sliding table and a coordinate card. The medical guide wire is a radiography guide wire, the interior of the medical guide wire is in a semi-hollow state, the four-core optical fiber is embedded into the tip end of the radiography guide wire, the FBGs are distributed on a fiber core of the four-core optical fiber, the prepared guide wire structure is fixed to a supporting rod provided with a clamp, and the pull and push dynamometer is arranged on an electric control displacement platform. Bending generated by horizontal collision of the tip end of the guide wire under the control of the motor is calibrated. The force sensor can be widely applied to medical interventional operations, and has the characteristic that the tip contact force is measurable, so that accurate detection of the contact stress of the guide wire and the blood vessel is realized, visual force feedback is formed, and the complication probability of the interventional operations is reduced. The invention relates to the technical field of novel medical devices.

Description

(I) Technical field

[0001] The present invention relates to the technical field of novel medical devices. Specifically, the present invention discloses an optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guide wire, which can be used in the treatment process of interventional minimally invasive surgery. (II) Background technology

[0002] Over the past two centuries, with the emergence and application of technologies such as endoscopes, surgical techniques have undergone major changes. Minimally invasive and interventional surgeries with advantages such as less trauma, faster recovery, and strong targeting have been widely used in clinical practice, gradually replacing traditional open surgeries. In order to achieve accurate and efficient minimally invasive interventional diagnosis and treatment, robot-assisted surgical techniques and instruments have received extensive attention and research, and their applications have developed rapidly. The birth of robotic surgery has successfully separated doctors from patients, avoiding laser radiation and making the operating environment safer for doctors. In recent years, clinical surgery has gradually developed in the direction of minimally invasive surgery, among which puncture surgery is one of the most common surgeries in minimally invasive surgery. At present, most surgical robots can only play the role of navigation and positioning, and lack force feedback technology.

[0003] For doctors, it is very necessary to accurately judge the contact between the guidewire and the blood vessel. The magnitude and degree of bending of the force applied to the blood vessel and the surrounding area during guidewire treatment are particularly critical. If the force applied is too large, it may cause complications of interventional surgery, while if the force applied is too small, the surgical treatment effect may not be achieved, resulting in a waste of medical resources. How to accurately judge the contact force between the guidewire and the blood vessel is a problem that needs to be solved urgently.

[0004] Surgical robots can use a composite force sensor that combines a medical guidewire with an optical fiber as a surgical manipulation tool for minimally invasive vascular surgery, thereby improving the success rate and safety of the surgery. In this process, temperature and strain will interfere with the changes in the resonant wavelength and intensity of the optical fiber sensor; therefore, it is important to have an optical fiber sensor that is not affected by temperature and strain.

[0005] The invention patent with application number 202310188367.X discloses a medical guidewire with a real-time detection function of three-dimensional force at the tip. The guidewire core is designed with a variable diameter nickel-titanium alloy wire to solve the problem of force support at different parts of the guidewire body during the pushing process of the guidewire in the human body; a Bragg grating fiber sensor array arranged at the flexible tip of the guidewire is designed to provide a certain force detection basis for doctors to operate vascular interventional surgery robots. However, the sensed force is a grating measurement feedback, lacking direct force display, and cannot be compared to determine whether it is an accurate force indication.

[0006] The present invention aims to propose a three-dimensional force sensing calibration platform for the tip of an interventional guidewire, wherein the embedded optical fiber is a triangular four-core optical fiber, and the temperature and strain response in all cores are consistent, thereby eliminating the interference of temperature and strain; it constructs a real and accurate tactile feedback at the tip of the guidewire operation, and compares the force indication and bending degree of the push-pull force gauge on the electric-controlled displacement platform with the data of the tip force measurement of the fiber grating to form a data corresponding calibration, thereby preparing a sensing calibration platform. The device has the characteristics of low cost, high resolution, high sensitivity, etc., and can be widely used in interventional surgery. (III) Summary of the invention

[0007] Based on this, the purpose of the present invention is to provide a fiber optic three-dimensional force sensing calibration platform for the tip of an interventional guidewire. The platform has the characteristic of measurable tip contact force, and introduces multi-core fiber gratings to realize tip force and temperature sensing of the interventional guidewire. The force indications of the push-pull force gauges on the electrically controlled displacement platform are compared with the tip force measurement data of the fiber grating to determine the precise feedback of the force sensation. At the same time, the bending degree of the guidewire and the wavelength change are compared and calibrated one by one, thereby achieving accurate judgment of the contact force between the guidewire and the blood vessel, reducing the probability of complications in interventional surgery, and improving the success rate of the surgery.

[0008] The object of the present invention is achieved in that:

[0009] It consists of an interventional medical guide wire, a multi-core optical fiber, a single-mode optical fiber, a heat diffusion coupler, multiple optical fiber Bragg gratings, a push-pull force gauge, a fixed support rod, an electric-controlled translation stage, a slide table and a coordinate card.

[0010] The medical guide wire is an angiography guide wire with a diameter range of 0.85-0.95mm, preferably 0.9mm in diameter, and a length of 0.5m. The head end is a hemispherical end structure, and the interior is treated to be a semi-hollow state. The inner core is made of nickel-titanium alloy and has two layers of coating. The bottom coating material is tungsten-containing polyurethane, and the second coating is a semi-ester methyl Z-olefin ether maleic anhydride copolymer. An independent card slot is provided inside the tip of the angiography guide wire, and the multi-core optical fiber is placed inside the guide wire core and connected with the groove, and the groove gap is 0.3mm. The tip has good flexibility, which is convenient for better contact to obtain the force condition, thereby constructing a real and fine tactile feedback.

[0011] The four-core optical fiber is a triangular four-core optical fiber with a cladding diameter of 125 μm, a central core at the center of the cladding and three side cores distributed in a regular triangle. It is embedded at the tip of the imaging guide wire. The middle core of the four-core optical fiber is located at the geometric center of the optical fiber, and its size matches that of the single-mode optical fiber. It is used for temperature measurement, and the side core is used to detect the stress condition of the guide wire tip.

[0012] The interventional medical guide wire, multi-core optical fiber, single-mode optical fiber, heat diffusion coupler, and multiple optical fiber gratings are combined to form a force sensor structure.

[0013] The heat diffusion coupler is prepared by heating the four-core optical fiber, and its purpose is to couple the single-mode optical fiber signal with the signal of the four-core optical fiber, so that the entire sensor can be measured in a single channel, which improves the integration of the device. The middle core of the four-core optical fiber is located at the geometric center of the optical fiber, and its size matches that of the single-mode optical fiber. It is used for temperature measurement, and the side core is used to detect the bending force on the tip of the guide wire. The single-mode optical fiber is connected to the grating demodulator through an optical fiber active connector.

[0014] The grating is engraved on the four-core optical fiber placed in the tip of the guidewire. Each core at the same axial position of the four-core optical fiber is engraved with a Bragg grating of different reflection wavelengths. During the single-channel measurement stage, the wavelength signals reflected back by each core do not interfere with each other. The strain and temperature of each core can be obtained through the sensitivity matrix, thereby obtaining the force condition of the interventional guidewire tip.

[0015] When the guide wire is subjected to bending force, the tip portion embedded with the four-core optical fiber will bend and deform, causing the wavelength of the grating placed in the tip to drift. The specific principle is as follows:

[0016] Bragg grating reflection center wavelength λ B Determined by formula (1): λ B =2n eff Λ (1)

[0017] Where Λ is the grating period and neff is the effective refractive index of the grating area.

[0018] The central core and three side cores of the triangular four-core optical fiber are all engraved with continuous Bragg gratings. According to the relevant theoretical knowledge of Bragg gratings, the wavelength change caused by the axial strain and temperature of the FBG is:

[0019] Where: Δλ B is the change in the grating center wavelength, n eff is the effective refractive index of the grating area, Λ is the period of the grating, ε is the applied strain, P i,j is the Pockels piezoelectric coefficient of the photoelastic tensor, v is the Poisson's ratio, α is the thermal expansion coefficient of the optical fiber material; ΔT is the temperature change.

[0020] The center wavelength of the grating is shifted by external factors, and the wavelength changes Δλ B The value of the measured physical quantity can be solved.

[0021] From formula (2), we can get the value of each fiber core:

[0022] From formula (3), we can see that the gratings of the four cores have the same response trend to temperature and strain along the fiber axis. By using this, the interference factor caused by the ambient temperature can be eliminated by subtracting the wavelength drift of the fiber gratings corresponding to the three side cores and the center core, so that formula (3) can be simplified to formula (4):

[0023]

[0024] When the tip of the guidewire is bent and deformed by force, there is the following relationship between the axial strain and curvature of the optical fiber:

[0025] In formula (5), ε is the axial surface strain value of the sensing position of the fiber Bragg grating area, ρ is the radius of curvature of the sensor sensing position, C is its corresponding curvature, and D is the distance from the force sensor to the neutral plane. Given the curvature and distance, the strain of the fiber Bragg grating can be calculated. From formulas (2) and (3), it can be seen that the strain is offset by Δλ from the central wavelength of the fiber Bragg grating. B So the curvature C is proportional to Δλ B In this way, the central wavelength shift Δλ of the fiber Bragg grating sensor can be observed. B The size of the curvature C can be changed by measuring the change in curvature C, and the stress condition of the optical fiber can be fed back in real time.

[0026] The fixed support rod is equipped with a vertically sliding slide, on which two optical fiber clamps are installed to stably fix the prepared force sensor. The front end of the push-pull force gauge has a force contact area, which can display the force magnitude in real time when in contact with force. The push-pull force gauge is placed on an electrically controlled displacement table that can slide horizontally at a uniform speed. It moves and collides with the tip of the guide wire force sensor, and the tip of the force sensor bends and deforms due to the force.

[0027] A coordinate card with an accuracy of 1mm is placed vertically behind the part where the tip of the guidewire collides with the force contact area of ​​the push-pull force gauge. When the tip is bent under force, the coordinate card can record the bending angle and coordinate position, providing data for subsequent calibration.

[0028] The fiber stress condition obtained by fiber Bragg grating strain is compared with the real-time force indication of the push-pull force gauge to ensure the accuracy of the measured bending force. The change of grating wavelength is compared and calibrated with the angle obtained by the coordinate card to achieve visual feedback of bending.

[0029] Compared with the prior art, the present invention has the following advantages:

[0030] 1. The grating force sensor structure used in the present invention can realize the process of placing optical fiber in the core of the angiography guide wire for force sensing detection. The fiber grating sensor has extremely high sensitivity and accuracy, good flexibility, small size, and integrates sensing and transmission. It is very suitable for integration into the tip of the guide wire; at the same time, it is combined with a thermal diffusion coupler to improve the structural integration. The inherent safety and corrosion resistance of the grating force sensor composite structure enable it to be used normally in radiation environments and vascular environments, thereby improving the success rate of interventional surgery.

[0031] 2. The optical fiber three-dimensional force sensing calibration platform at the tip of the interventional guidewire described in the present invention obtains the force value of the optical fiber through the grating strain of the force sensor and compares it with the indication measured by the push-pull force gauge, so as to determine the accuracy of the measured bending force value. The grating wavelength change is compared with the degree of guidewire bending to form a calibration, so that the degree of guidewire bending during blood vessel pushing can be quickly reflected through different wavelength changes, highlighting the real-time feedback characteristics of the platform. (IV) Description of the drawings

[0032] Figure 1 This is a schematic diagram of the sensor calibration platform, where: 1-interventional medical guide wire, 2-slide table, 3-push-pull force gauge, 4-electrically controlled translation stage, 5-optical fiber clamp, 6-force contact area, 7-coordinate card.

[0033] Figure 2 It is a schematic diagram of the tip of an interventional medical guidewire, where 1-1 is a triangular four-core optical fiber, 1-2 is a single-mode optical fiber, 1-3 is a double coating, and 1-4 is a triangular four-core optical fiber cross-section.

[0034] Figure 3 It is a schematic diagram of the structure of a four-core optical fiber thermal diffusion coupler, where 1-1 is a triangular four-core optical fiber, 1-2 is a single-mode optical fiber, 1-3 is a double coating, 1-5 is a thermal diffusion coupler, and 8 is a four-core optical fiber Bragg grating.

[0035] FIG. 4 is a schematic diagram of the deformation of the force sensor before (a) and during (b) contact. (V) Specific implementation methods

[0036] The present invention is described in detail below in conjunction with the accompanying drawings and specific embodiments. This embodiment is implemented based on the technical solution of the present invention, and provides a detailed implementation method and specific operation process, but the protection scope of the present invention is not limited to the following embodiments.

[0037] This embodiment provides a fiber optic three-dimensional force sensing calibration platform for the tip of an interventional guidewire. The tip contact force of the surgical medical guidewire in the platform can be measured, thereby realizing the measurement of the force generated when the guidewire contacts the vascular tissue, thereby reducing the harm caused by excessive or insufficient force during surgery.

[0038] like Figure 2 As shown, this embodiment provides a multi-core fiber Bragg grating three-dimensional force sensor for the tip of a guidewire for vascular interventional surgery, which includes an interventional medical guidewire, a multi-core optical fiber, and a plurality of FBG sensors, wherein the medical guidewire is an angiography guidewire, the interior of which is in a semi-hollow state, the multi-core optical fiber is a triangular four-core optical fiber and is embedded and fixed to the semicircular tip of the angiography guidewire, and the plurality of FBG sensors are distributed on the central core and three side cores of the multi-core optical fiber. The medical guidewire is an angiography guidewire, and the diameter ranges from 0.85 to 0.95 mm, and preferably, the diameter is 0.9 mm. The inner core of the medical guidewire is a nickel-titanium alloy with two layers of coating, the base coating material is a tungsten-containing polyurethane, and the second coating is a semi-ester methyl Z-olefin ether maleic anhydride copolymer, the length of which is 0.5 m, the tip of the guidewire is a hemispherical structure, and the tip has good flexibility.

[0039] The sensor is placed on a slide with two optical fiber clamps, and can move vertically and smoothly with the slide on the fixed support rod to match the height of the right electric-controlled translation stage. The front end of the push-pull force gauge has a force contact area, which can display the force magnitude in real time when in contact. The push-pull force gauge is placed on an electric-controlled translation stage that can slide horizontally at a constant speed. It collides with the tip of the guide wire through constant speed movement, and the tip bends and deforms due to the force, as shown in Figure 4(b).

[0040] like Figure 3 As shown in the figure, the thermal diffusion coupler is obtained by heating the welding point between the triangular four-core fiber and the single-mode fiber. The principle is that during the heating process, the elements in the fiber core diffuse outward, so that the middle core signal of the four-core fiber is coupled with the side core. When the coupling ratio reaches a suitable state, the heating ends. At this time, the light emitted from the single-mode fiber will be coupled to the four cores of the four-core fiber along the middle core of the four-core fiber through the thermal diffusion area. The heating time is usually 90-100 minutes.

[0041] When the tip of the guide wire contacts and collides with the force-bearing area of ​​the push-pull force gauge, in order to effectively distinguish the stress changes of each core when using a single channel for triangular four-core optical fiber signal demodulation, a core-by-core writing method should be adopted when grating writing is performed on the multi-core optical fiber, so that the four cores of the four-core optical fiber have different Bragg grating reflection wavelengths.

[0042] When the guide wire tip is subjected to force contact and collision, the grating wavelength on the optical fiber will drift. The drift direction and drift amount of the three side cores on the triangular four-core optical fiber are different. By detecting the wavelength change of the grating on the three side cores, the bending of the four-core optical fiber can be deduced, and the force value of the guide wire tip can be fed back. At this time, the force value corresponding to the different wavelength changes is recorded.

[0043] The middle core in the center of the triangular four-core fiber will not be affected when the fiber is bent, and the grating written on it only responds to temperature. Therefore, by measuring the grating of the middle core, the temperature value of the tip of the guide wire can be detected.

[0044] The push-pull force gauge placed on the electric control displacement stage is not in motion as shown in Figure 4(a). When sliding horizontally at a constant speed, it gradually touches the tip of the guide wire, resulting in bending deformation, as shown in Figure 4(b). The deformation is recorded on the coordinate card at the back, and the bending angle and coordinate position of the bending part are recorded. Combined with the push-pull force gauge display, the force condition of the guide wire tip when it is bent is obtained.

[0045] The sliding process of the push-pull force gauge causes the tip of the guide wire to bend, resulting in different degrees of bending deformation and bending angles, which corresponds to the process of bending deformation of the guide wire when it is pushed into the blood vessel during interventional surgery.

[0046] The wavelength change and force value obtained by the grating change at the same time are compared with the bending angle and force real number obtained by the pushing device on the right side of Figure 4(b). The deviation of the two force values ​​is within 1%, which confirms the feasibility of the force measurement of the calibration platform and reflects its accuracy. A set of wavelength changes corresponds to a set of bending angle changes, so the bending degree and force of the interventional guidewire in the process of blood vessel pushing can be calibrated by the wavelength change.

Claims

1. An optical fiber three-dimensional force sensing calibration platform for an interventional guidewire tip, characterized in that: It consists of an interventional medical guide wire, a multi-core optical fiber, a single-mode optical fiber, a heat diffusion coupler, a plurality of FBGs (hereinafter replaced by optical fiber gratings), a push-pull force gauge, a fixed support rod, an electrically controlled displacement table, a slide table and a coordinate card. The medical guide wire is an angiographic guide wire, the interior of which is in a semi-hollow state. The optical fiber is a single-mode four-core optical fiber and is embedded and fixed to the semicircular tip of the angiographic guide wire. The plurality of FBG sensors are distributed on the central core and three side cores of the multi-core optical fiber.

2. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: The medical guide wire is an angiography guide wire, and its diameter ranges from 0.85mm to 0.95mm.

3. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: The inside of the medical guide wire is processed into a semi-hollow state, a groove is provided on the inner side of the tip of the guide wire, the multi-core optical fiber is connected to the groove in an anastomosing manner, and the groove gap is 0.3mm.

4. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: The inner side of the medical guide wire is made of nickel-titanium alloy and has two layers of coating, the base coating material is tungsten-containing polyurethane, and the second coating material is half-ester methyl Z-olefin ether maleic anhydride copolymer.

5. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: The length of the medical guide wire is 0.5 m, the tip of the guide wire is a hemispherical structure, and the contact performance of the tip is good.

6. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: The multi-core optical fiber is a triangular four-core optical fiber, and its structure includes a central core at the center of the cladding and three side cores distributed in a regular triangle.

7. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: The cladding diameter of the multi-core optical fiber is 125 μm.

8. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: A continuous Bragg grating is inscribed inside the core of the triangular four-core optical fiber.

9. The optical fiber three-dimensional force sensing calibration platform for the tip of an interventional guidewire according to claim 1, characterized in that: The force sensor structure is fixed on a fixed support rod equipped with a clamp, and the dynamometer is placed on an electrically controlled displacement platform. It is controlled by a motor to perform horizontal collision on the tip of the guide wire. The dynamometer displays the horizontal force on the tip of the guide wire in real time, and the bending angle of the guide wire tip is recorded by the coordinate card when it bends.

Images