Piercing needle with tip three-dimensional force sensor

Abstract

This invention discloses a puncture needle with a three-dimensional force sensor at the needle tip, comprising: an outer needle and an inner needle; the inner needle is axially bonded together with an inner needle body and a needle tip for encapsulating a fiber Bragg grating (FBG); the inner needle body is a hollow tube, the interior of which can be used to bundle and protect the optical fiber; the outer diameter of the inner needle body is the same as the outer diameter of the needle tip; the inner needle and outer needle are fitted together without gaps, the inner needle is slightly longer than the outer needle, and the needle tip of the inner needle protrudes from the needle tube of the outer needle; the needle tip is a cylinder with a pointed cone at one end to achieve puncture. The three-dimensional force sensor integrated into the tip of the inner needle can directly serve as the feedback basis for the puncture force. The sensor does not directly contact the tissue, reducing the risk of medical adhesives contacting the tissue; compared with creating grooves and parallel slot structures on a nickel-titanium alloy tube through laser processing, this invention greatly reduces the processing difficulty and cost; after puncture, the hollow tube can be left for surgery by withdrawing the inner needle.

Description

Technical Field

[0001] This invention relates to the field of medical device technology, specifically a puncture needle with a three-dimensional force sensor at the needle tip. Background Technology

[0002] Currently, cranial nerve puncture is one of the commonly used neurosurgical procedures for diagnosing and treating cranial nerve diseases, offering advantages such as being minimally invasive, reliable, and safe. This procedure is included in surgeries such as brain biopsy and deep brain stimulation. During the surgery, since the position of the puncture needle within the tissue cannot be visualized, registration and navigation rely on the insertion depth and preoperative MRI images. However, during the procedure, factors such as brain displacement and edema can cause errors in traditional preoperative image registration. Intraoperative MRI, using an MRI scanner in the operating room, allows surgeons to obtain MRI images during the procedure, providing "real-time" feedback. Therefore, surgical tools have increasingly incorporated the requirement of "MRI compatibility."

[0003] For puncture procedures, ruptured blood vessels and subsequent intracranial hemorrhage are critical concerns. Some studies have confirmed that force feedback can improve the operator's ability to distinguish between different tissues and reduce tissue damage and the duration of the procedure. For puncture needles, the most direct point for assessing the "needle-brain" interaction is the force applied to the needle tip.

[0004] There are two existing approaches to force feedback in puncture surgery. The first approach involves installing a force sensor at the needle base, mapping the force at the needle base to the force on the puncture needle using an Euler-Bernoulli beam model. The second approach involves directly installing a three-dimensional force sensor at the needle tip to sense the force signal received at the tip. Regarding the specific implementation of these two approaches: sensors based on strain gauge, capacitive, resistive, and piezoelectric sensing principles have drawbacks such as low biocompatibility, difficulty in integration with medical devices, and susceptibility to electromagnetic interference; while fiber optic sensors, with their small outer diameter, good biocompatibility, resistance to electromagnetic interference, and ease of sterilization, are easily integrated into medical devices.

[0005] The first approach, which integrates the fiber optic sensor into the needle base, is relatively simple, but the change in the cutting force of the needle tip can be affected by the shear friction between the needle shaft and the surrounding tissue.

[0006] The second approach, integrating a fiber optic sensor at the needle tip, directly reflects changes in the puncture force applied to the needle tip, making it the optimal force feedback solution. However, this approach is more difficult to integrate. Patent CN111803143A discloses integrating a fiber Bragg grating (FBG) sensor into the tip of a minimally invasive surgical needle. This sensor is attached to the outside of the needle tube, leaving a hollow channel for working space. However, this sensor comes into direct contact with soft tissue during puncture, increasing the risk of the adhesive used for sensor encapsulation coming into direct contact with brain tissue, which can be detrimental. Furthermore, this patent requires laser-machining three grooves on a thin-walled nickel-titanium alloy tube to attach the fiber optic cable, along with a parallel, interlaced groove structure. Currently, laser machining of such fine structures is difficult and costly.

[0007] Considering the above factors, the present invention proposes a puncture needle with a three-dimensional force sensor at the needle tip, which can better solve the problems of the two existing solutions. Summary of the Invention

[0008] To address the aforementioned problems, this invention provides a puncture needle with a three-dimensional force sensor at the needle tip.

[0009] A puncture needle with a three-dimensional force sensor at the tip includes: an outer needle 20 and an inner needle 30; the inner needle 30 is axially bonded together with an inner needle body 31 and a needle tip 32 for encapsulating a fiber Bragg grating (FBG); the inner needle body 31 is a hollow tube, the interior of which can be used to bundle and protect the optical fiber; the outer diameter of the inner needle body 31 is the same as the outer diameter of the needle tip 32; the inner needle 30 and the outer needle 20 are fitted together without gaps, and the length of the inner needle 30 is slightly longer than that of the outer needle 20; the needle tip 32 of the inner needle 30 protrudes from the needle tube of the outer needle 20; the needle tip 32 is a cylinder with a pointed tip at one end, and puncture can be achieved through the pointed tip of the needle tip 32;

[0010] The puncture needle with a three-dimensional force sensor at the tip also includes a needle seat 10 at the end opposite to the needle tip 32, which is used to lock and separate the inner needle 30 and the outer needle 20; the needle seat 10 includes an inner needle seat 11 and an outer needle seat 12, which are respectively bonded to the inner needle 30 and the outer needle 20.

[0011] The inner needle body 31 has N uniformly polished slits at one end connected to the needle tip 32 of the inner needle 30, and N grooves 36 are uniformly opened around the needle tip 32 for attaching and fixing N optical fibers respectively.

[0012] The two ends 33 and 35 of the needle tip 32 of the inner needle 30 are both made of 3D printing material, and the two ends 33 and 35 of the needle tip 32 are bonded together by alloy wire 34;

[0013] To achieve three-dimensional force sensing under temperature compensation, two fiber Bragg gratings (FBGs) with the same grating spacing are attached to each of the N optical fibers, forming two sets of fiber Bragg gratings FBG-1 and FBG-2. The N grating regions of each set of fiber Bragg gratings FBG are located in the same plane. FBG-1 is attached to the N optical fibers around the alloy wire 34 of the needle 32, and FBG-2 is attached to the N optical fibers around the two ends 33 or 35 of the needle 32.

[0014] Optionally, the outer needle holder 12 includes two right-angle slots, each of which consists of an interconnected axial slot and a circumferential slot; the inner needle holder 11 includes two locking points; by sliding the two locking points into the two axial slots of the outer needle holder 12 and then rotating the inner needle holder 11 to make the two locking points slide into the circumferential slots of the outer needle holder 12, the inner needle 30 and the outer needle 20 can be locked; by rotating the inner needle holder 11 in the opposite direction and removing the two locking points, the inner needle 30 and the outer needle 20 can be separated.

[0015] Optionally, the range and sensitivity of the three-dimensional force sensor can be changed by altering the material of the alloy wire 34.

[0016] Optionally, to achieve three-dimensional force sensing under temperature compensation, the two ends 33 and 35 of the needle 32 and the axis of the alloy wire 34 each have through holes. An optical fiber is pasted in the through holes, and a fiber Bragg grating (FBG-1) is pasted on the part of the optical fiber located inside the alloy wire 34. A fiber Bragg grating (FBG) is pasted on the part of each of the N optical fibers located at the end 33 or 35, forming a set of fiber Bragg gratings (FBG-2). The N grating regions of this set of fiber Bragg gratings (FBG-2) are located in the same plane.

[0017] Optionally, the two ends 33 and 35 of the needle tip 32 of the inner needle 30 are both made of resin material by 3D printing; the optical fiber is bonded while the optical fiber is in a pre-stretched state.

[0018] Optionally, both the outer needle 20 and the inner needle body 31 are made of nickel-titanium alloy tubing; the alloy wire 34 is a nickel-titanium alloy wire.

[0019] An analytical method for a puncture needle with a three-dimensional force sensor at the tip, based on a force-strain model of an inner and outer needle stacked structure, wherein the three-dimensional force sensor is considered as a series and parallel connection of multiple springs, when an axial force is applied... F zAt the FBG-1 section, the spring K1, which is approximately formed by the alloy wire 34, and the spring K3, which is approximately formed by the optical fiber, are connected in parallel; at the FBG-2 section, the spring K2, which is approximately formed by the puncture needle, and the spring K3, which is approximately formed by the optical fiber, are connected in parallel; finally, the two sets of parallel springs are connected in series.

[0020] Assume the grating region length of the fiber Bragg grating (FBG) is... L Therefore, the forces acting on FBG-1 and FBG-2 are equal in magnitude, both being axial forces. F z , can be represented as:

[0021] Formula (1);

[0022] In the above formula (1), k 1. k 2. k 3 represents the spring constants of springs K1, K2, and K3, respectively. ε 1. ε 2 represents the axial strain of FBG-1 and FBG-2, respectively; the axial strain and axial force F z The relationship between wavelength drift and axial strain is linear and can be expressed as follows:

[0023] Formula (2);

[0024] In the above formula (2), and Wavelength shifts for FBG-1 and FBG-2, respectively. and These represent wavelength drift, respectively. and Axial force F z The sensitivity, where ΔT is the temperature change. and These represent wavelength drift, respectively. and Sensitivity to temperature change ΔT;

[0025] When a lateral force is applied F l At this time, the outer needle (20) and inner needle (30) of the puncture needle can be regarded as two freely stacked beams. When the puncture needle is subjected to bending moment... M When bending occurs, assuming the bending moments experienced by the outer needle (20) and the inner needle (30) are respectively... M 1. M 2. From the static equilibrium condition, we can obtain:

[0026] Formula (3);

[0027] The outer needle (20) and the inner needle (30) are respectively equivalent to Euler-Bernoulli beams. Since the outer needle (20) and the inner needle (30) are closely fitted and coaxial, their radii of curvature are equal.

[0028] Formula (4);

[0029] In the above formula (4), E 1. E 2 represents the equivalent elastic modulus of the outer needle (20) and the inner needle (30), respectively. I 1. I 2 represents the moments of inertia of the outer needle (20) and the inner needle (30) about their respective neutral axes, from which the bending moment on the inner needle (30) can be obtained. M 2 is:

[0030] Formula (5);

[0031] Let the distance between FBG-2 and the needle tip be... b When the needle tip is subjected to a lateral force F l At that time, the bending moment at FBG-2 M for:

[0032] Formula (6);

[0033] The curvature k at FBG-2 is:

[0034] Formula (7);

[0035] Strain of each fiber Bragg grating FBG-2_i ε 2i for:

[0036] Formula (8);

[0037] In the above formula (8), l i The distance from the fiber to the central axis of the inner needle (30) is used to apply the lateral force. F l Decomposed into two mutually orthogonal directions, X and Y, to obtain F x , F y The strain of the fiber Bragg grating FBG-2_i is then... ε 2i for:

[0038] Formula (9);

[0039] In the above formula (9), x i and y i These represent the distances from the N optical fibers to the XZ and YZ planes, respectively; the strain and transverse force of the optical fibers. F l If they are directly proportional, then the lateral force F l Caused wavelength drift and F x 、F y The relationship can be represented as:

[0040] Formula (10);

[0041] In the above formula (10), and The wavelength drift of the N fibers of FBG-2 affects the axial force. F z The sensitivity; the factors affecting the wavelength drift of the fiber Bragg grating (FBG) are divided into three categories: transverse force. F l Axial force F z Temperature change ΔT; For N fiber Bragg gratings (FBGs) at the same cross-section, with equal center wavelengths, when temperature T and axial force... F z When the wavelength changes, N fiber Bragg gratings (FBGs) will produce the same wavelength shift, therefore the N FBGs will exert the same axial force. F z Sensitivity coefficient of temperature T C z , C t Equal for lateral force F l Sensitivity coefficient C 1 , C 2 , C 3 Unlike other wavelength shifts, wavelength shift can be expressed as:

[0042] Formula (11);

[0043] Since the N fiber Bragg gratings (FBGs) are distributed at equal angular intervals of 120° along the central axis, the lateral sensitivity coefficient satisfies:

[0044] Formula (12);

[0045] The lateral force can be obtained by taking the common mode of N fiber Bragg gratings (FBGs). F l Separately, the result is only related to the axial force. F z Since it is related to temperature T, the average wavelength drift of N fiber Bragg gratings (FBGs) with the same cross-section is defined as... This quantity affects the axial force. F z The sensitivity coefficients for the temperature change ΔT are respectively and Their relationship can be expressed as:

[0046] Formula (13);

[0047] lateral force F l Caused wavelength drift It can be represented as:

[0048] Formula (14);

[0049] In the above formula (14), and The wavelength drift of the N fibers of FBG-2 affects the axial force. F z Sensitivity; therefore, lateral force F l With axial force F z To achieve decoupling, formulas (13) and (14) are transformed into the following matrix forms:

[0050] Formula (15);

[0051] Formula (16);

[0052] Based on the above formulas (15) and (16), the wavelength drift decoupling of the fiber Bragg grating (FBG) can be obtained through calibration to obtain the three-dimensional force. F x , F y , F z .

[0053] The beneficial effects of the technical solution of this invention are as follows:

[0054] This invention provides a puncture needle with a three-dimensional force sensor integrated at the needle tip. The three-dimensional force sensor integrated at the needle tip can directly serve as the feedback basis for the puncture force, and is not affected by the interaction force between the needle axis and brain tissue. The sensor is integrated on the inner needle and does not come into direct contact with brain tissue, reducing the risk of medical adhesives coming into contact with tissue. Compared with creating grooves and parallel slot structures on a nickel-titanium alloy tube by laser processing, this design greatly reduces the processing difficulty and processing cost. After puncture, the inner needle can be withdrawn to leave a hollow channel for the surgery. Attached Figure Description

[0055] Figure 1 This is a general structural diagram of a puncture needle with a three-dimensional force sensor at the needle tip according to an embodiment of the present invention;

[0056] Figure 2 This is a diagram of the inner needle structure of a puncture needle with a three-dimensional force sensor at the tip, according to an embodiment of the present invention.

[0057] Figure 3 This is a structural diagram of a three-dimensional force sensor for a puncture needle with a three-dimensional force sensor at the tip, according to an embodiment of the present invention.

[0058] Figure 4 This is a structural diagram of a puncture needle with a three-dimensional force sensor at the needle tip, according to another embodiment of the present invention. Detailed Implementation

[0059] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. It should be understood that the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] To address the problems of existing solutions, this invention designs a puncture needle with a three-dimensional force sensor. This sensor is based on a fiber Bragg grating (FBG) and can monitor the puncture force information at the needle tip in real time while performing temperature compensation.

[0061] A fiber Bragg grating (FBG) is an optical reflection grating composed of a series of equally spaced refractive index regions. When light passes through the FBG, light of a specific wavelength is reflected back, forming a reflection peak. This specific wavelength is the center wavelength of the fiber Bragg grating.

[0062]

[0063] in, It is the reflection center wavelength of the FBG. It is the equivalent refractive index of the fiber core. This refers to the grating spacing. Changes in strain and temperature affect the equivalent refractive index and grating spacing, thus causing changes in the center wavelength.

[0064]

[0065] When FBG is used as a force sensor, temperature changes can cause interference, so temperature compensation is necessary.

[0066] This invention addresses the need for needle-brain force sensing during brain nerve puncture surgery by designing a puncture needle with a three-dimensional force sensor at the needle tip based on a fiber Bragg grating (FBG). This puncture needle can be used for puncture tasks during brain nerve puncture procedures such as stereotactic biopsy of brain tissue or DBS (deep brain stimulation) surgery, and can monitor the force between the needle tip and brain tissue in real time during the puncture. Simultaneously, this puncture needle can also be used for various puncture tasks (viscera, muscle tissue, etc.) with all ultra-fine puncture needles (outer diameter less than 2 mm).

[0067] It should be noted that the puncture needle with a three-dimensional force sensor at the needle tip, as claimed in this invention, is applicable not only to NMR environments but also to non-NMR environments. Measuring the puncture force at the needle tip with a small diameter is a common problem, with similar requirements in both NMR and non-NMR (i.e., ordinary) puncture processes. When used in a non-NMR environment, the puncture needle can be made from a wider range of materials.

[0068] Example 1:

[0069] First, in order to solve the problem of direct contact between the sensor and brain tissue, the puncture needle was designed with an inner and outer needle structure.

[0070] Figure 1 This is a general structural diagram of a puncture needle with a three-dimensional force sensor at the needle tip according to an embodiment of the present invention.

[0071] like Figure 1 As shown, a puncture needle with a three-dimensional force sensor at the tip includes: an outer needle 20 and an inner needle 30; the inner needle 30 is axially bonded together with an inner needle body 31 and a needle tip 32 for encapsulating a fiber Bragg grating (FBG); the inner needle body 31 is a hollow tube, the interior of which can be used to bundle and protect the optical fiber; the outer diameter of the inner needle body 31 is the same as the outer diameter of the needle tip 32; the inner needle 30 is fitted to the outer needle 20 without gaps, and the length of the inner needle 30 is slightly longer than that of the outer needle 20, with the needle tip 32 of the inner needle 30 protruding from the needle tube of the outer needle 20; the needle tip 32 is a cylinder with a pointed tip at one end, allowing puncture to be performed through the pointed tip of the needle tip 32.

[0072] The puncture needle with a three-dimensional force sensor at the tip also includes a needle seat 10 at the end opposite to the needle tip 32, which is used to lock and separate the inner needle 30 and the outer needle 20; the needle seat 10 includes an inner needle seat 11 and an outer needle seat 12, which are respectively bonded to the inner needle 30 and the outer needle 20.

[0073] The outer needle holder 12 includes two right-angle slots, each of which consists of an interconnected axial slot and a circumferential slot. The inner needle holder 11 includes two locking points. By sliding the two locking points into the two axial slots of the outer needle holder 12 and then rotating the inner needle holder 11 to make the two locking points slide into the circumferential slots of the outer needle holder 12, the inner needle 30 and the outer needle 20 can be locked. By rotating the inner needle holder 11 in the opposite direction and removing the two locking points, the inner needle 30 and the outer needle 20 can be separated.

[0074] Figure 2 This is a diagram of the inner needle structure of a puncture needle with a three-dimensional force sensor at the needle tip, according to an embodiment of the present invention.

[0075] like Figure 2 As shown, to achieve temperature compensation, two fiber gratings with different sensitivities are needed to eliminate the influence of temperature. Therefore, the 3D-printed needle tip 32 is cut in the middle and connected with another material. Considering NMR compatibility, a nickel-titanium alloy wire 34 is used for bonding. At the same time, the range and sensitivity of the three-dimensional force sensor can be changed by changing the material of the connecting wire (essentially Young's modulus), thereby enabling the puncture needle to be used in different puncture scenarios. A nickel-titanium alloy hollow tube with the same diameter as the needle tip 32 is taken as the main body of the inner needle 30, i.e., the inner needle body 31. To facilitate the fiber bundled into the hollow tube of the inner needle body 31 to protect the fiber, three evenly ground slits are made at the end of the inner needle body 31 that connects to the needle tip 32 of the inner needle 30; then the needle tip 32 of the inner needle 30 is bonded to the inner needle body 31.

[0076] A nickel-titanium alloy hollow tube with the same diameter as the needle tip 32 is used as the main body of the inner needle 30, namely the inner needle body 31. In order to facilitate the fiber to be bundled into the hollow tube of the inner needle body 31 and protect the fiber, three cuts are evenly ground at the end of the inner needle body 31 that is connected to the needle tip 32 of the inner needle; then the needle tip 32 of the inner needle is bonded to the inner needle body 31.

[0077] Figure 3 This is a structural diagram of a three-dimensional force sensor for a puncture needle with a three-dimensional force sensor at the tip, according to an embodiment of the present invention.

[0078] To achieve three-dimensional force sensing with temperature compensation, the three optical fibers are bonded as follows. Figure 3As shown, each optical fiber has two fiber Bragg gratings (FBGs) with equal spacing between the grating regions. The grating regions of the three optical fibers are aligned one-to-one, placing them on two planes, thus forming two groups, FBG-1 and FBG-2. During bonding, FBG-1 is placed around the nickel-titanium alloy wire, and FBG-2 is placed around the 3D-printed resin material. This ensures that the force sensitivity of the FBGs at the two locations is no longer the same after bonding, thereby achieving temperature compensation. To prevent uneven strain caused by differences in adhesive layer thickness during bonding, a suspended bonding method is used, where the two ends of the grating region are bonded to the sensitive element, rather than directly bonding the grating region to the sensitive element. To improve linearity, the optical fibers are bonded under pre-stretch conditions.

[0079] The force-strain model of the puncture needle with its internal and external needle structure is analyzed below:

[0080] When axial force is applied F z When performing a force analysis on the cross section where the fiber optic grating is located, the sensor can be considered as a series and parallel connection of multiple springs. At the FBG-1 section, the spring K1, approximately formed by the alloy wire (34), and the spring K3, approximately formed by the optical fiber, are connected in parallel; at the FBG-2 section, the spring K2, approximately formed by the puncture needle, and the spring K3, approximately formed by the optical fiber, are connected in parallel. Finally, the two sets of parallel springs are connected in series. Assume that the length of the fiber optic grating region is... L Therefore, the forces acting on FBG-1 and FBG-2 are equal in magnitude, both being axial forces. F z , can be represented as:

[0081] Formula (1)

[0082] in, k 1. k 2. k 3 represents the spring constants of springs K1, K2, and K3, respectively. ε 1. ε 2 represents the strain of FBG-1 and FBG-2, respectively. Therefore, the axial strain and axial force... F z The relationship between wavelength drift and axial strain is linear and can be expressed as follows:

[0083] Formula (2)

[0084] in, and Wavelength shifts for FBG-1 and FBG-2, respectively. and These represent the effect of wavelength drift on axial force. F z The sensitivity, where ΔT is the temperature change. and This indicates the sensitivity of wavelength drift to changes in temperature.

[0085] When a lateral force is applied F l At this time, the outer needle 20 and inner needle 30 of the puncture needle can be regarded as a freely combined composite beam (the beams can slide relative to each other without friction). When the puncture needle is subjected to a bending moment M and bends, the two layers of beams slide relative to each other, so the entire puncture needle cannot satisfy the plane assumption. Let's assume that the bending moment of the outer needle 20 is... M 1. The bending moment experienced by the inner needle 30 is M 2. From the static equilibrium condition, we can obtain:

[0086] Formula (3)

[0087] The outer needle 20 and the inner needle 30 are respectively equivalent to Euler-Bernoulli beams. The outer needle 20 and the inner needle 30 are closely fitted and coaxial, so their radii of curvature are equal.

[0088] Formula (4)

[0089] in, E 1. E 2 represents the equivalent elastic modulus of the outer needle 20 and the inner needle 30. I 1. I 2 represents their moments of inertia along their respective neutral axes, from which the bending moment experienced by the inner needle 30 can be obtained. M 2 is:

[0090] Formula (5)

[0091] Let the distance between FBG-2 and the needle tip be... b When the needle tip is subjected to a lateral force F l At that time, the bending moment at FBG-2 M for:

[0092] Formula (6)

[0093] The curvature κ at FBG-2 is:

[0094] Formula (7)

[0095] Strain of fiber Bragg grating FBG-2_i ε 2i for:

[0096] Formula (8)

[0097] In the formula,l i The distance from the fiber optic cable to the central axis of the inner needle 30 is used to apply lateral force. F l Decomposed into two mutually orthogonal directions, X and Y. F x , F y The strain of the fiber Bragg grating FBG-2_i ε 2i for:

[0098] Formula (9)

[0099] in x i and y i These represent the distances from the three optical fibers to the XZ and YZ planes, respectively. Therefore, the fiber strain is related to the transverse force. F l Proportional, lateral force F l Caused wavelength drift and F x 、F y The relationship can be represented as:

[0100] Formula (10)

[0101] in and Wavelength drift of the three fibers of FBG-2 on axial force F z The sensitivity. Factors affecting the wavelength drift of a fiber Bragg grating (FBG) are categorized into three types: transverse force... F l Axial force F z Temperature change ΔT. For three fiber Bragg gratings (FBGs) at the same cross-section, with equal center wavelengths, temperature T and axial force... F z When the temperature T changes, the three fiber Bragg gratings (FBGs) will produce the same wavelength shift, meaning the three FBGs will respond to temperature T and axial force changes. F z Sensitivity coefficient ( C t , C z Equal to the lateral force F l Sensitivity coefficient ( C 1 ,C 2 , C 3 The difference can be expressed as:

[0102] Formula (11)

[0103] Since the three fiber Bragg gratings (FBGs) are evenly distributed along the central axis at 120° angular intervals, the lateral sensitivity coefficient satisfies:

[0104] Formula (12)

[0105] The lateral force can be obtained by taking the common mode of three fiber Bragg gratings (FBGs). F l Separately, the result is only related to the axial force. F z Since it is related to temperature T, the average wavelength drift of three fiber Bragg gratings (FBGs) with the same cross-section is defined as... This quantity affects the axial force. F z The sensitivity coefficients for the temperature change ΔT are respectively and Their relationship can be expressed as:

[0106] Formula (13)

[0107] lateral force F l Caused wavelength drift It can be represented as:

[0108] Formula (14)

[0109] and Wavelength drift of the three fibers of FBG-2 on axial force F z The sensitivity of the lateral force. Therefore, the lateral force... F l With axial force F z To achieve decoupling, the above formulas (13) and (14) can be written in matrix form as follows:

[0110] Formula (15)

[0111] Formula (16)

[0112] Therefore, a three-dimensional force can be obtained by calibrating and decoupling the wavelength drift of the six fiber Bragg gratings (FBGs). F x , F y , F z .

[0113] The design, development, and three-dimensional force sensing principle of the puncture needle are as described above. Using this puncture needle, during the puncture process, the inner needle 30 and outer needle 20 are simultaneously inserted to reach the target point. After the puncture is completed, the needle seat 10 of the inner needle 30 can be rotated to separate the inner needle 30 from the outer needle 20, and the inner needle 30 can be withdrawn from the needle tube of the outer needle 20, leaving a hollow tube for subsequent implantation of brain tissue biopsy needles or DBS (deep brain stimulation) electrode wires. Furthermore, this puncture needle is not limited to brain tissue puncture; it can also be used for punctures of internal organs, muscles, etc. After the inner needle is removed, a working space is created for drug administration, biopsy, etc.

[0114] Example (II):

[0115] Figure 4 This is a structural diagram of a puncture needle with a three-dimensional force sensor at the needle tip, according to another embodiment of the present invention.

[0116] In this embodiment, the fiber optic cable arrangement of the inner needle 30 tip is not unique. In addition to the arrangement of 3 optical fibers with 2 gratings on each optical fiber mentioned in Embodiment 1 of the present invention, a 4-fiber arrangement method can also be used.

[0117] like Figure 4 As shown, the three optical fibers are still evenly attached to the outside of the needle tip, but each fiber has only one grating, and the three gratings are located in the same cross-section. Simultaneously, there is a hollow hole at the center of the needle tip to attach the optical fiber. The grating on this fiber should be located at the connecting tube of a different material, unlike the cross-sections of the other three gratings. This fiber arrangement is the same as the "force-strain" model described in this paper, and it can also perform three-dimensional force sensing and temperature compensation.

[0118] Although the invention has been specifically shown and described in conjunction with preferred embodiments, those skilled in the art should understand that various changes in form and detail may be made to the invention without departing from the spirit and scope of the invention as defined in the appended claims, all of which shall be within the scope of protection of the invention.

Claims

1. A puncture needle with a three-dimensional force sensor at the needle tip, characterized in that, include: The outer needle (20) and the inner needle (30) are provided. The inner needle (30) is formed by axially bonding an inner needle body (31) and a needle tip (32) for encapsulating a fiber Bragg grating (FBG). The inner needle body (31) is a hollow tube, which can be used to bundle and protect the optical fiber. The outer diameter of the inner needle body (31) is the same as the outer diameter of the needle tip (32). The inner needle (30) and the outer needle (20) are fitted together without gaps, and the length of the inner needle (30) is slightly longer than that of the outer needle (20). The needle tip (32) of the inner needle (30) protrudes from the needle tube of the outer needle (20). The needle tip (32) is a cylinder with a pointed cone at one end, and puncture can be achieved through the pointed cone of the needle tip (32). The puncture needle with a three-dimensional force sensor at the tip also includes a needle seat (10) at the end opposite to the needle tip (32) to lock and separate the inner needle (30) and the outer needle (20); the needle seat (10) includes an inner needle seat (11) and an outer needle seat (12), and the inner needle seat (11) and the outer needle seat (12) are respectively bonded to the inner needle (30) and the outer needle (20); The inner needle body (31) has N uniformly polished slits at one end connected to the needle tip (32) of the inner needle (30), and N grooves (36) are uniformly opened around the needle tip (32) for attaching and fixing N optical fibers respectively. The two ends (33 and 35) of the needle tip (32) of the inner needle (30) are made of 3D printing material, and the two ends (33 and 35) of the needle tip (32) are bonded together by alloy wire (34); To achieve three-dimensional force sensing under temperature compensation, two fiber Bragg gratings (FBGs) with the same grating spacing are attached to each of the N optical fibers, forming two sets of fiber Bragg gratings FBG-1 and FBG-2. The N grating regions of each set of fiber Bragg gratings FBG are located in the same plane. FBG-1 is attached to the N optical fibers around the alloy wire (34) of the needle (32), and FBG-2 is attached to the N optical fibers around the two ends (33 or 35) of the needle (32).

2. The puncture needle with a three-dimensional force sensor at the needle tip according to claim 1, characterized in that, The outer needle holder (12) includes two right-angle slots, each of which consists of an interconnected axial slot and a circumferential slot. The inner needle holder (11) includes two locking points. By sliding the two locking points into the two axial slots of the outer needle holder (12) and then rotating the inner needle holder (11) to make the two locking points slide into the circumferential slot of the outer needle holder (12), the inner needle (30) and the outer needle (20) can be locked. By rotating the inner needle holder (11) in the opposite direction and pulling out the two locking points, the inner needle (30) and the outer needle (20) can be separated.

3. The puncture needle with a three-dimensional force sensor at the needle tip according to claim 2, characterized in that, The range and sensitivity of the three-dimensional force sensor can be changed by altering the material of the alloy wire (34).

4. The puncture needle with a three-dimensional force sensor at the needle tip according to claim 3, characterized in that, To achieve three-dimensional force sensing under temperature compensation, the two ends (33 and 35) of the needle (32) and the axis of the alloy wire (34) are all provided with through holes. An optical fiber is attached to the through hole, and a fiber Bragg grating FBG-1 is attached to the part of the optical fiber located inside the alloy wire (34). A fiber Bragg grating FBG is attached to the part of each of the N optical fibers located at the end (33 or 35), forming a set of fiber Bragg gratings FBG-2. The N grating regions of the set of fiber Bragg gratings FBG-2 are located in the same plane.

5. The puncture needle with a three-dimensional force sensor at the needle tip according to claim 4, characterized in that, The two ends (33 and 35) of the needle tip (32) of the inner needle (30) are both made of resin material by 3D printing; the optical fiber is bonded while the optical fiber is in a pre-stretched state.

6. The puncture needle with a three-dimensional force sensor at the needle tip according to claim 5, characterized in that, The outer needle (20) and the inner needle body (31) are both made of nickel-titanium alloy tubes; the alloy wire (34) is a nickel-titanium alloy wire.

7. An analysis method for a "force-strain" model based on the inner and outer needle stacked structure of a puncture needle with a three-dimensional force sensor at the needle tip, applicable to any one of claims 1-6, characterized in that, The three-dimensional force sensor can be viewed as a series and parallel connection of multiple springs. When an axial force is applied... F z At the FBG-1 section, the spring K1, which is approximately formed by the alloy wire (34), and the spring K3, which is approximately formed by the optical fiber, are connected in parallel; at the FBG-2 section, the spring K2, which is approximately formed by the puncture needle, and the spring K3, which is approximately formed by the optical fiber, are connected in parallel; finally, the two sets of parallel springs are connected in series. Assume the grating region length of the fiber Bragg grating (FBG) is... L Therefore, the forces acting on FBG-1 and FBG-2 are equal in magnitude, both being axial forces. F z , can be represented as: Official (1); In the above formula (1), k 1. k 2. k 3 represents the spring constants of springs K1, K2, and K3, respectively. ε 1. ε 2 represents the axial strain of FBG-1 and FBG-2, respectively; the axial strain and axial force F z The relationship between wavelength drift and axial strain is linear and can be expressed as follows: Official (2); In the above formula (2), and Wavelength shifts for FBG-1 and FBG-2, respectively. and These represent wavelength drift, respectively. and Axial force F z The sensitivity, where ΔT is the temperature change. and These represent wavelength drift, respectively. and Sensitivity to temperature change ΔT; When a lateral force is applied F l At this time, the outer needle (20) and inner needle (30) of the puncture needle can be regarded as two freely stacked beams. When the puncture needle is subjected to bending moment... M When bending occurs, assuming the bending moments experienced by the outer needle (20) and the inner needle (30) are respectively... M 1. M 2. From the static equilibrium condition, we can obtain: Official (3); The outer needle (20) and the inner needle (30) are respectively equivalent to Euler-Bernoulli beams. Since the outer needle (20) and the inner needle (30) are closely fitted and coaxial, their radii of curvature are equal. Official (4); In the above formula (4), E 1. E 2 represents the equivalent elastic modulus of the outer needle (20) and the inner needle (30), respectively. I 1. I 2 represents the moments of inertia of the outer needle (20) and the inner needle (30) about their respective neutral axes, from which the bending moment on the inner needle (30) can be obtained. M 2 is: Official (5); Let the distance between FBG-2 and the needle tip be... b When the needle tip is subjected to a lateral force F l At that time, the bending moment at FBG-2 M for: Official (6); The curvature k at FBG-2 is: Official (7); Strain of each fiber Bragg grating FBG-2_i ε 2i for: Official (8); In the above formula (8), l i The distance from the fiber to the central axis of the inner needle (30) is used to apply the lateral force. F l Decomposed into two mutually orthogonal directions, X and Y, to obtain F x , F y The strain of the fiber Bragg grating FBG-2_i is then... ε 2i for: Official (9); In the above formula (9), x i and y i These represent the distances from the N optical fibers to the XZ and YZ planes, respectively; the strain and transverse force of the optical fibers. F l If they are directly proportional, then the lateral force F l Caused wavelength drift and F x 、F y The relationship can be represented as: Official (10); In the above formula (10), and The wavelength drift of the N fibers of FBG-2 affects the axial force. F z The sensitivity; the factors affecting the wavelength drift of the fiber Bragg grating (FBG) are divided into three categories: transverse force. F l Axial force F z Temperature change ΔT; For N fiber Bragg gratings (FBGs) at the same cross-section, with equal center wavelengths, when temperature T and axial force... F z When the wavelength changes, N fiber Bragg gratings (FBGs) will produce the same wavelength shift, therefore the N FBGs will exert the same axial force. F z Sensitivity coefficient of temperature T C z , C t Equal for lateral force F l Sensitivity coefficient C 1 , C 2 , C 3 Unlike other wavelength shifts, wavelength shift can be expressed as: Official (11); Since the N fiber Bragg gratings (FBGs) are distributed at equal angular intervals of 120° along the central axis, the lateral sensitivity coefficient satisfies: Official (12); The lateral force can be obtained by taking the common mode of N fiber Bragg gratings (FBGs). F l Separately, the result is only related to the axial force. F z Since it is related to temperature T, the average wavelength drift of N fiber Bragg gratings (FBGs) with the same cross-section is defined as... This quantity affects the axial force. F z The sensitivity coefficients for the temperature change ΔT are respectively and Their relationship can be expressed as: Official (13); lateral force F l Caused wavelength drift It can be represented as: Official (14); In the above formula (14), and The wavelength drift of the N fibers of FBG-2 affects the axial force. F z Sensitivity; therefore, lateral force F l With axial force F z To achieve decoupling, formulas (13) and (14) are transformed into the following matrix forms: Official (15); Official (16); Based on the above formulas (15) and (16), the wavelength drift decoupling of the fiber Bragg grating (FBG) can be obtained through calibration to obtain the three-dimensional force. F x , F y , F z .

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