In-vivo muscle force testing system and method based on FBG sensor

Abstract

The invention discloses an in-vivo muscle force testing system and method based on an FBG sensor, and relates to the technical field of testing. Comprising an FBG sensor, an E-shaped piece, a wavelength demodulator and a display, wherein the FBG sensor is arranged on the upper surface along the axis direction of the middle arm of the E-shaped piece; the grating of the FBG sensor tests the acting force perpendicular to the axis direction of the middle arm of the E-shaped piece, the other end of the FBG sensor is connected to the wavelength demodulator to receive the wavelength of the optical fiber reflected light, and the wavelength demodulator transmits the wavelength of the optical fiber reflected light to the displayer to be displayed. According to the invention, the optical fiber is arranged on the upper surface of the middle arm of the E-shaped piece, and through the analysis of a combined stress model of the E-shaped piece and the tendon, an accurate mapping relation from the wavelength of reflected light of the FBG sensor to the axial force of the muscle is established. The muscle strength in-vivo test can be carried out, and the test method has the remarkable advantages of being simple, high in test precision and the like.

Description

Technical Field

[0001] This invention relates to the field of testing technology, and specifically to an in vivo muscle strength testing system and method based on an FBG sensor. Background Technology

[0002] Skeletal muscles are the primary power source of the human musculoskeletal system, enabling movement by forcefully contracting and pulling on the bones. The strength of skeletal muscles is crucial for surgical precision. Understanding muscle strength helps surgeons perceive muscle status during surgery, allowing for operative force feedback and control based on muscle strength levels, thus laying the foundation for improved surgical accuracy and safety.

[0003] Currently, the main methods for measuring muscle force include resistance strain gauges, pressure sensors, and electromyography (EMG). While these methods can reflect changes in muscle force to some extent, they also have limitations. For example, the signals measured by resistance strain gauges are usually very weak, requiring high-precision amplification and signal processing systems. Furthermore, contact between the strain gauge and muscle may cause allergies or other biocompatibility issues. Pressure sensor methods require calibration procedures such as zero-point checks, data recording, consistency, and hysteresis analysis for high-precision measurements, increasing complexity and inconvenience. EMG infers the active contractile force of muscles by recording electrical signals of muscle activity, while passive muscle force is not accompanied by significant electrical activity. The above testing methods primarily target surface forces of muscles. Testing axial forces that vary with muscle length typically involves dissecting the muscle and performing in vitro testing using a stretching machine. Therefore, in vivo methods for testing muscle forces generated by axial stretching or compression have limitations.

[0004] Therefore, proposing an in vivo muscle strength testing system and method based on FBG sensors to overcome the difficulties of existing technologies is a problem that urgently needs to be solved by those skilled in the art. Summary of the Invention

[0005] In view of this, the present invention provides an in vivo muscle strength testing system and method based on an FBG sensor. The use of an FBG sensor avoids weak signal and biocompatibility issues, simplifies the muscle strength testing system and its calibration process, improves the sensitivity of muscle strength detection and the accuracy of test results, and achieves accurate measurement of muscle strength.

[0006] To achieve the above objectives, the present invention adopts the following technical solution:

[0007] An in vivo muscle strength testing system based on an FBG sensor includes: an FBG sensor, an E-shaped component, a wavelength demodulator, and a display; wherein,

[0008] The FBG sensor is arranged on the surface of the E-shaped part along the axis of the middle arm of the E-shaped part; the grating of the FBG sensor measures the force perpendicular to the axis of the middle arm of the E-shaped part; the other end of the FBG sensor is connected to a wavelength demodulator to receive the wavelength of the light reflected from the optical fiber, and the wavelength demodulator transmits the wavelength of the light reflected from the optical fiber to the display for display.

[0009] In the above system, optionally, the FBG sensor is a single optical fiber with a single segment of Bragg grating inscribed on it, and the fiber grating area is arranged on the intermediate arm of the E-shaped component.

[0010] Optionally, the E-shaped component in the above system is an integral structure, consisting of a side arm, a middle arm, a right arm, and a left arm. The middle arm, right arm, and left arm are evenly spaced, forming a groove between adjacent arms, and the end of the arm has a round hole.

[0011] An in vivo muscle strength testing method based on an FBG sensor, comprising the following steps, executing any of the above-described in vivo muscle strength testing systems based on an FBG sensor:

[0012] S1. E-shaped component fabrication: Prepare an integral E-shaped component with overall dimensions matching the tendon of the muscle being tested;

[0013] S2. FBG sensor fabrication: Select a single-segment Bragg grating fiber, with the grating length matched to the size of the middle arm of the E-shaped component, and place the FBG sensor on the surface of the middle arm of the E-shaped component.

[0014] S3. Test equipment connection: Connect the fiber optic connector of the FBG sensor to the wavelength demodulator to ensure accurate data transmission and recording;

[0015] S4. Fixation of the tested tendon: Fix the obtained tested tendon onto the E-shaped piece;

[0016] S5. Muscle strength test: Record the wavelength information of the light reflected by the optical fiber during the movement of the tested muscle.

[0017] S6. Data Processing: Based on the changes in wavelength information of the reflected light from the optical fiber, analyze the corresponding changes in tendon axial force to obtain the final muscle force data.

[0018] Optionally, in the above method, the specific way to fix the obtained tendon to be tested onto the E-shaped component in S4 is as follows:

[0019] The tendon of the muscle being tested enters from one side of the E-shaped piece, passes through the first groove, and then exits from the second groove. The tendon forms a curved path below the middle arm of the E-shaped piece. Through the structural support and fixation of the E-shaped piece, it ensures that the axial force of the tendon is perpendicular to the arm length direction of the E-shaped piece.

[0020] The above method, optionally, uses the following mechanical model for fixing the tested tendon to the E-shaped component:

[0021]

[0022] In the formula, F is the axial force transmitted by the tendon, θ is the angle formed by the tendon bending, F2 is the force exerted by the tendon on the right arm of the E-shaped part, F1 is the force exerted by the tendon on the middle arm of the E-shaped part, d is the diameter of the tendon, and l is the width of the groove of the E-shaped part.

[0023] In the above method, optionally, the intermediate arm of the E-shaped component is equivalent to a cantilever beam. According to the deformation theory of beams, after being subjected to a tendon force F1, the deflection curve equation of the intermediate arm is:

[0024]

[0025] In the formula, y is the deflection, which represents the deformation of the intermediate arm of the E-shaped part along the direction perpendicular to its length; x is the distance from the fixed end of the intermediate arm to any point on it; c is the distance between the fixed end and the point of action of F1; L is the length of the intermediate arm; E is its elastic modulus; and I is the moment of inertia of the section of the intermediate arm.

[0026] Optionally, in the above method, the E-shaped component is adhered to the grid region of the FBG sensor. After the E-shaped component is stretched by the axial force of the tendon, the grid region length is:

[0027]

[0028] In the formula, a is the distance from the fixed end of the intermediate arm to the starting point of the grid area, b is the distance from the fixed end of the intermediate arm to the ending point of the grid area, and y' is the derivative of the deformation perpendicular to the axis of the intermediate arm with respect to x.

[0029] Optionally, the strain generated by the FBG sensor in the above method is:

[0030]

[0031] In the formula, λ B Δλ is the center wavelength of the FBG sensor. B p is the offset of the wavelength of the reflected light from the FBG sensor. e s0 is the effective strain optical coefficient of the optical fiber, s0 is the original length of the grating region, Δs is the elongation of the grating region, and s1 is the length of the grating region after elongation.

[0032] As can be seen from the above technical solution, compared with the prior art, the present invention provides an in vivo muscle strength testing system and method based on an FBG sensor, which has the following beneficial effects:

[0033] (1) In this invention, the optical fiber is arranged on the upper surface of the middle arm of the E-shaped component. Through the analysis of the combined force model of the E-shaped component and the tendon, a precise mapping relationship between the axial force of the muscle and the wavelength of the reflected light from the FBG sensor can be established.

[0034] (2) The present invention uses FBG sensor as strain gauge instead of traditional resistive strain gauge, which can solve the problem of electromagnetic interference to output signal and simplify muscle strength testing system and calibration process.

[0035] (3) The minimum strain accuracy that this invention can test is 10. -6 It has high accuracy and resolution, and the FBG sensor has the advantages of small size and light weight;

[0036] (4) The present invention uses an FBG sensor, whose substrate material is made of biocompatible material, which has little impact on biological tissues;

[0037] (5) This invention can perform both isolated muscle strength testing and in vivo robot testing. Attached Figure Description

[0038] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the provided drawings without creative effort.

[0039] Figure 1 A structural block diagram of an in vivo muscle strength testing system based on an FBG sensor provided by the present invention;

[0040] Figure 2 A flowchart of an in vivo muscle strength testing method based on an FBG sensor provided by the present invention;

[0041] Figure 3 This invention provides a schematic diagram illustrating the force exerted by the tendon on the E-shaped component.

[0042] Figure 4 The stress deformation diagram of the intermediate arm of the E-shaped component provided by the present invention;

[0043] Figure 5 The deformation principle diagram of the cantilever beam under intermediate stress provided by the present invention;

[0044] Among them, 1-FBG sensor, 2-E-shaped component, 3-tendon, 4-muscle, 5-E-shaped component middle arm, 6-E-shaped component right arm, 7-E-shaped component left arm, 8-side arm, 9-wavelength demodulator, 10-display. Detailed Implementation

[0045] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, 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.

[0046] Reference Figure 1 As shown, this invention discloses an in vivo muscle strength testing system based on an FBG sensor, comprising: an FBG sensor 1, an E-shaped component 2, a wavelength demodulator 9, and a display 10; wherein,

[0047] FBG sensor 1 is arranged on the surface of E-shaped part 2 along the axis of the intermediate arm 5 of E-shaped part; the grating of FBG sensor 1 measures the force perpendicular to the axis of the intermediate arm 5 of E-shaped part; the other end of FBG sensor 1 is connected to wavelength demodulator 9 to receive the wavelength of the reflected light from the optical fiber; wavelength demodulator 9 transmits the wavelength of the reflected light from the optical fiber to display 10 for display.

[0048] Furthermore, the FBG sensor 1 is a single optical fiber with a single-segment Bragg grating inscribed on it, and the fiber grating area is arranged on the intermediate arm 5 of the E-shaped component.

[0049] Furthermore, the E-shaped component 2 is an integral structure, consisting of a side arm 8, an E-shaped middle arm 5, an E-shaped right arm 6, and an E-shaped left arm 7. The E-shaped middle arm 5, E-shaped right arm 6, and E-shaped left arm 7 are evenly spaced, and a groove is formed between adjacent arms. The ends of the left and right arms have round holes.

[0050] Specifically, the positional relationship between the FBG sensor 1, tendon 3 and E-shaped component 2 is as follows: E-shaped component 2 is an integral structure, shaped like the English letter "E". It is mainly composed of a side arm 8 and three protruding arms. The three arms are evenly spaced and a groove is formed between adjacent arms.

[0051] The tendon 3 enters from one side of the E-shaped member 2, passes through the first slot, and then exits from the second slot. The tendon 3 forms a natural curved path below the middle arm 5 of the E-shaped member, and the axial force of the tendon is perpendicular to the arm length direction of the E-shaped member 2.

[0052] The FBG sensor 1 is arranged on the surface of the E-shaped part 2 along the axial direction of the intermediate arm 5 of the E-shaped part, and the fiber optic grid area is arranged on the intermediate arm 5 of the E-shaped part, which can detect the force exerted by the tendon 3 on the intermediate arm 5 of the E-shaped part.

[0053] and Figure 1 Corresponding to the aforementioned system, this embodiment of the invention also provides an in vivo muscle strength testing method based on an FBG sensor, the flowchart of which is shown below. Figure 2As shown, the specific steps include:

[0054] S1, Fabrication of E-shaped component 2: Prepare an integral E-shaped component 2 with overall dimensions matching the tendon 3 of the muscle 4 being tested;

[0055] S2, Fabrication of FBG sensor 1: Select a single-segment Bragg grating fiber, and match the length of the grating area with the size of the intermediate arm 5 of the E-shaped part. Arrange the FBG sensor 1 on the surface of the intermediate arm 5 of the E-shaped part.

[0056] S3. Test equipment connection: Connect the fiber optic connector of FBG sensor 1 to wavelength demodulator 9 to ensure accurate data transmission and recording;

[0057] S4. Fixation of the tested tendon: Fix the obtained tested tendon 3 onto the E-shaped piece 2;

[0058] S5. Muscle strength test: Record the wavelength information of the light reflected by the optical fiber during the movement of the tested muscle 4.

[0059] S6. Data Processing: Based on the changes in wavelength information of the reflected light from the optical fiber, analyze the corresponding changes in tendon axial force to obtain the final muscle force data.

[0060] Furthermore, the specific method for fixing the acquired tendon 3 to the E-shaped component 2 in S4 is as follows:

[0061] The tendon 3 of the muscle 4 being tested enters from one side of the E-shaped piece 2, passes through the first groove, and then exits from the second groove. The tendon 3 forms a curved path under the middle arm 5 of the E-shaped piece. Through the structural support and fixation of the E-shaped piece 2, it ensures that the axial force direction of the tendon is perpendicular to the arm length direction of the E-shaped piece 2.

[0062] Furthermore, such as Figure 3 As shown, the mechanical model of the tendon 3 being tested fixed on the E-shaped component 2 is as follows:

[0063]

[0064] In the formula, F is the axial force transmitted by the tendon, θ is the angle formed by the tendon bending, F2 is the force exerted by the tendon on the right arm of the E-shaped part, F1 is the force exerted by the tendon on the middle arm of the E-shaped part, d is the diameter of the tendon, and l is the width of the groove of the E-shaped part.

[0065] Furthermore, Figure 4 This is a force-deformation diagram of the intermediate arm. The intermediate arm of the E-shaped component is equivalent to a cantilever beam. Based on the deformation principle of curved beams, the deformation principle diagram of a cantilever beam under stress in the middle is shown below. Figure 5 As shown, according to the beam deformation theory, after being subjected to a force F1 from the tendon, the equation of the deflection curve of the intermediate arm is:

[0066]

[0067] In the formula, y is the deflection, which represents the deformation of the intermediate arm of the E-shaped part along the direction perpendicular to its length; x is the distance from the fixed end of the intermediate arm to any point on it; c is the distance between the fixed end and the point of action of F1; L is the length of the intermediate arm; E is its elastic modulus; and I is the moment of inertia of the section of the intermediate arm.

[0068] Furthermore, the E-shaped component 2 adheres to the grid region of the FBG sensor 1. After the E-shaped component 2 is stretched by the axial force of the tendon 3, the grid region length is:

[0069]

[0070] In the formula, a is the distance from the fixed end of the intermediate arm to the starting point of the grid area, b is the distance from the fixed end of the intermediate arm to the ending point of the grid area, and y' is the derivative of the deformation perpendicular to the axis of the intermediate arm with respect to x.

[0071] Furthermore, the strain generated by FBG sensor 1 is:

[0072]

[0073] In the formula, λ B Δλ is the center wavelength of the FBG sensor. B p is the offset of the wavelength of the reflected light from the FBG sensor. e s0 is the effective strain optical coefficient of the optical fiber, s0 is the original length of the grating region, Δs is the elongation of the grating region, and s1 is the length of the grating region after elongation.

[0074] In one specific embodiment, the following is included:

[0075] S1, Fabrication of E-shaped component 2: Prepare an integral E-shaped component 2 with overall dimensions matching the tendon 3 of the muscle 4 being tested;

[0076] S2, FBG sensor 1 fabrication: Select a single-segment Bragg grating fiber. The length of the grating area is determined by the size of the intermediate arm 5 of the E-shaped part, and shall not exceed half the length of the intermediate arm 5 of the E-shaped part. Arrange it on the surface of the intermediate arm 5 of the E-shaped part.

[0077] S3. Test equipment connection: Connect the fiber optic connector to the wavelength demodulator 9 to ensure accurate data transmission and recording;

[0078] S4. Fixing the muscle being tested: Fix the tendon 3 to the E-shaped piece 2, and use medical sutures to pass through the round holes on the arm of the E-shaped piece 2 in sequence to prevent the tendon 3 from slipping off.

[0079] S5. Muscle movement: When testing muscle strength in vivo, muscles can be moved in various ways, such as: voluntary movement of the organism being tested, applying appropriate electrical stimulation to the target muscle, stretching or squeezing the muscle by external force, etc.

[0080] S6. Muscle strength test: Record the wavelength information of the light reflected by the optical fiber during muscle movement.

[0081] S7. Data Processing: Based on the changes in the wavelength of the reflected light from the optical fiber, analyze the corresponding changes in the axial force of the tendon to obtain the final muscle force data.

[0082] Specifically, by preparing an E-shaped component 2 that matches the tendon 3 to be tested and an FBG sensor 1, the tendon 3 is fixed on the E-shaped component 2, and the optical fiber is connected to the wavelength demodulator 9 to transmit test data. The wavelength demodulator 9 transmits the wavelength of the light reflected from the optical fiber to the display 10 for display.

[0083] Specifically, firstly, before starting the test, a dynamometer is used to calibrate the axial force of the tendon. A high-strength thin wire with similar size and tensile properties to the tendon 3 is fixed to the E-shaped component 2. Different tensile forces are applied to both ends of the thin wire, and the changes in the wavelength of the reflected light from the optical fiber are recorded to obtain the mapping relationship between the axial force and the wavelength of the reflected light. Secondly, the tendon 3 is fixed to the E-shaped component 2, and a medical thin wire is used to prevent it from slipping. The wavelength changes during the activity of the muscle 4 are recorded in real time, and the muscle force data is analyzed to ensure the real-time nature and accuracy of the test results.

[0084] Specifically, when fixing the optical fiber in S2, in order to make the optical fiber's response to strain more obvious, the fiber grating area should be arranged on the middle arm 5 of the E-shaped member near the side arm 8.

[0085] Specifically, when fixing the tendon 3 of the muscle 4 being tested in S4, it should be ensured that the axial force of the muscle is perpendicular to the arm length direction of the E-shaped piece 2.

[0086] The various embodiments in this specification are described in a progressive manner, with each embodiment focusing on its differences from other embodiments. Similar or identical parts between embodiments can be referred to interchangeably. For the apparatus disclosed in the embodiments, since they correspond to the methods disclosed in the embodiments, the description is relatively simple; relevant parts can be referred to the method section.

[0087] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An in vivo muscle strength testing system based on an FBG sensor, characterized in that, include: FBG sensor (1), E-shaped component (2), wavelength demodulator (9), display (10); among which, The FBG sensor (1) is arranged on the surface of the E-shaped part (2) along the axis of the intermediate arm (5) of the E-shaped part; the grating of the FBG sensor (1) measures the force perpendicular to the axis of the intermediate arm (5) of the E-shaped part; the other end of the FBG sensor (1) is connected to the wavelength demodulator (9) to receive the wavelength of the optical fiber reflected light; the wavelength demodulator (9) transmits the wavelength of the optical fiber reflected light to the display (10) for display.

2. The in vivo muscle strength testing system based on an FBG sensor according to claim 1, characterized in that, The FBG sensor (1) is a single optical fiber with a single segment of Bragg grating written on it. The fiber grating area is arranged on the intermediate arm (5) of the E-shaped component.

3. The in vivo muscle strength testing system based on an FBG sensor according to claim 1, characterized in that, The E-shaped part (2) is an integral structure, consisting of a side arm (8), an E-shaped middle arm (5), an E-shaped right arm (6), and an E-shaped left arm (7). The E-shaped middle arm (5), E-shaped right arm (6), and E-shaped left arm (7) are evenly spaced, and a groove is formed between adjacent arms. There is a round hole at the end of the arm.

4. A method for in vivo muscle strength testing based on an FBG sensor, characterized in that, The in vivo muscle strength testing system based on an FBG sensor, as described in any one of claims 1-3, comprises the following steps: S1, E-shaped component (2) fabrication: Prepare an integral E-shaped component (2) with an overall size that matches the tendon (3) of the muscle (4) being tested; S2, FBG sensor (1) fabrication: Select a single-segment Bragg grating fiber, and match the grating length with the size of the E-shaped intermediate arm (5). Arrange the FBG sensor (1) on the surface of the E-shaped intermediate arm (5). S3. Test equipment connection: Connect the fiber optic connector of the FBG sensor (1) to the wavelength demodulator (9) to ensure accurate data transmission and recording; S4. Fixation of the tested tendon: Fix the obtained tested tendon (3) onto the E-shaped piece (2); S5, Muscle strength test: Record the wavelength information of the light reflected by the optical fiber during the movement of the tested muscle (4); S6. Data Processing: Based on the changes in wavelength information of the reflected light from the optical fiber, analyze the corresponding changes in tendon axial force to obtain the final muscle force data.

5. The in vivo muscle strength testing method based on an FBG sensor according to claim 4, characterized in that, The specific method for fixing the obtained test tendon (3) onto the E-shaped piece (2) in S4 is as follows: The tendon (3) of the muscle (4) being tested enters from one side of the E-shaped piece (2), passes through the first groove, and then exits from the second groove. The tendon (3) forms a curved path under the middle arm (5) of the E-shaped piece. Through the structural support and fixation of the E-shaped piece (2), it ensures that the axial force direction of the tendon is perpendicular to the arm length direction of the E-shaped piece (2).

6. The in vivo muscle strength testing method based on an FBG sensor according to claim 5, characterized in that, The mechanical model of the tested tendon (3) fixed on the E-shaped member (2) is as follows: In the formula, F is the axial force transmitted by the tendon, θ is the angle formed by the tendon bending, F2 is the force exerted by the tendon on the right arm of the E-shaped part, F1 is the force exerted by the tendon on the middle arm of the E-shaped part, d is the diameter of the tendon, and l is the width of the groove of the E-shaped part.

7. The in vivo muscle strength testing method based on an FBG sensor according to claim 6, characterized in that, The intermediate arm (5) of the E-shaped component is equivalent to a cantilever beam. According to the deformation theory of beams, after being subjected to the force F1 of the tendon, the deflection curve equation of the intermediate arm is: In the formula, y is the deflection, which represents the deformation of the intermediate arm of the E-shaped part along the direction perpendicular to its length; x is the distance from the fixed end of the intermediate arm to any point on it; c is the distance between the fixed end and the point of action of F1; L is the length of the intermediate arm; E is its elastic modulus; and I is the moment of inertia of the section of the intermediate arm.

8. The in vivo muscle strength testing method based on an FBG sensor according to claim 4, characterized in that, The E-shaped component (2) is adhered to the grid area of ​​the FBG sensor (1). After the E-shaped component (2) is stretched by the axial force of the tendon (3), the grid area length is: In the formula, a is the distance from the fixed end of the intermediate arm to the starting point of the grid area, b is the distance from the fixed end of the intermediate arm to the ending point of the grid area, and y' is the derivative of the deformation perpendicular to the axis of the intermediate arm with respect to x.

9. The in vivo muscle strength testing method based on an FBG sensor according to claim 4, characterized in that, The strain generated by the FBG sensor (1) is: In the formula, λ B Δλ is the center wavelength of the FBG sensor. B p is the offset of the wavelength of the reflected light from the FBG sensor. e s0 is the effective strain optical coefficient of the optical fiber, s0 is the original length of the grating region, Δs is the elongation of the grating region, and s1 is the length of the grating region after elongation.

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