CN104783865B - A Laparoscopic 3D Force Sensing Grasper Based on Fiber Bragg Grating - Google Patents

Abstract

The present invention relates to a kind of laparoscope three-dimensional force based on Fiber Bragg Grating FBG senses nipper.Including nipper head：Fiber Bragg Grating FBG optical signal is converted to for clamping tissue and by clamping force signal；Driving handle：Apply for extraneous load, curable grip is converted to closing force needed for nipper；Connection sleeve pipe：For connecting nipper head and driving handle, and optical signal is reached signal processing unit.Described laparoscope three-dimensional force sensing nipper just apparatus is converted to optical signal with function of organization power, by fiber Bragg grating (FBG) demodulator collection and the computerized algorithm decoupling of design, recovers perception of the surgeon for apparatus function of organization power.The present invention, have the advantages that sensor bulk compact, possess biocompatibility, sterilizability, electromagnetism interference, can be provided in laparoscopic surgery in real time power feel feedback with assist surgeon realize accurately power control, lifted operation safety.

Description

A Laparoscopic 3D Force Sensing Grasper Based on Fiber Bragg Grating

technical field

The invention relates to a medical device, in particular to a three-dimensional force sensing grasper for laparoscopic surgery.

Background technique

At present, surgeons can only estimate the force exerted by the instrument on the tissue through visual information feedback, that is, the deformation of the tissue, because they cannot directly contact the tissue in the patient's body when performing laparoscopic surgery. Due to the friction of the trocar, the resistance of the abdominal wall, the influence of the proportional coefficient, and the structure of the instrument, the force information has been distorted when it is transmitted to the surgeon through the instrument, which will lead to slipping of the instrument or excessive clamping force. Clamping different types of tissue can lead to adverse surgical outcomes such as damaged tissue, formation of pathological scar tissue, bleeding, adhesion to surgical instruments, and loss of gastric motility. Therefore, the restoration of force sense information during surgery is particularly important to avoid slippage of tissues and instruments and the application of excessive force.

In order to restore the physician's perception of instrument-tissue forces, force sensors need to be integrated into surgical instruments. However, in addition to the basic requirements of high sensitivity, high robustness, minimum zero point and sensitivity drift, the requirements for the sensor itself in laparoscopic surgery also have its special application requirements, such as biocompatibility, sterilizable, compact Size, anti-electromagnetic interference, disposable, etc. Traditional force sensors, such as capacitive, piezoresistive, piezoelectric, and strain gauge sensors, are difficult to meet the special requirements of surgical situations. Therefore, in order to meet the requirements of the surgical field, it is necessary to find a new type of sensing technology for force feedback in laparoscopic surgery.

In recent years, fiber Bragg grating sensing technology based on wavelength decoding has gradually appeared in biomedical applications due to its advantages of electromagnetic immunity, high sensitivity and high repeatability. When broadband light propagates in the optical fiber, the light satisfying the Bragg condition (that is, the wavelength is the Bragg wavelength) will be reflected back, and the light of the remaining wavelengths can continue to be transmitted. When the fiber strain changes, the effective refractive index and grating period of the fiber Bragg grating will change, so that the Bragg wavelength will change. Therefore, the change of the substrate strain can be detected by detecting the shift of the reflection spectrum.

For fiber Bragg grating technology, Johns Hopkins University has used it in retinal surgery hooks to obtain the force between instruments and membranes; Dublin University of Technology has used this technology in medical scissors to obtain tissue shear force and analyze tissue fracture toughness. Evaluation; the University of Bern used it in ENT surgery to obtain the force of the instrument to crimp the stapes. However, there is no report on the results of its use in minimally invasive surgery in China.

Therefore, if the sensing technology can be combined with structural design in laparoscopic surgery, a laparoscopic grasper with integrated three-dimensional force sensing can be designed. The sensor is compact, biocompatible and sterilizable, and resistant to Electromagnetic interference, high precision, good repeatability and dynamic performance. It can be used for real-time force feedback when grasping tissue during surgery, which can assist surgeons to achieve precise force control and improve the safety of laparoscopic surgery.

Contents of the invention

Aiming at the problem that surgeons cannot obtain the interaction force between instruments and tissues in current laparoscopic surgery, the present invention proposes a three-dimensional force-sensing laparoscopic surgical grasper integrated with fiber Bragg gratings, which can acquire force sense in real time during surgery Feedback. The designed laparoscopic grasper is not only compact in structure, high in sensitivity and good in decoupling, but also can be used in the MRI operating environment, enabling the surgeon to implement precise force control on the tissue, reducing the trauma of the instrument to the tissue, and improving the operation efficiency. safety.

In order to solve the problems of the technologies described above, the present invention adopts the following technical solutions:

A laparoscopic three-dimensional force sensing grasper based on fiber Bragg grating, characterized in that it includes:

Force-sensing grasper head, used to clamp tissue and convert clamping force signal into fiber Bragg grating optical signal;

The drive handle is used for external load application and converts the holding force into the closing force required by the force sensing gripper head;

The connecting sleeve is used to connect the force sensing gripper head and the driving handle, and transmit the optical signal to the signal processing unit;

The signal processing unit is used to convert the optical signal into a digital signal and display it.

Further, the driving handle includes a rotating handle, a gripping handle and a driving slider arranged in the gripping handle;

The connecting sleeve includes an inner conduit with two rows of parallel optical fiber channels, an outer sleeve sleeved outside the inner conduit, an upper steel wire rope and a lower steel wire rope fixed in the outer sleeve, and an optical fiber connector;

The force sensing gripper head includes a gripper head body and four fiber Bragg gratings;

The signal processing unit includes a fiber grating demodulator and a computer;

The gripper head body is composed of an upper gripper head and a lower gripper head, the upper gripper head and the lower gripper head are hinged by pins, and are connected to the upper wire rope and the lower wire rope respectively. One end of the outer sleeve is connected, the other end of the outer sleeve is connected with the rotary handle, and the inner conduit extends from the outer sleeve to connect with the drive slider;

One end of the first fiber Bragg grating and the second fiber Bragg grating are embedded in the upper gripper head, one end of the third fiber Bragg grating and the fourth fiber Bragg grating is embedded in the lower gripper head, the first fiber Bragg grating The other ends of the grating and the second fiber Bragg grating are connected with the other ends of the third fiber Bragg grating and the fourth fiber Bragg grating respectively through two rows of parallel fiber channels to one end of the fiber connector, and the other end of the fiber connector The input end of the fiber grating demodulator is externally connected, and the output end of the fiber grating demodulator is connected with a computer.

Further, the material of the gripper body is a low elastic modulus biopolymer material.

Further, the first fiber Bragg grating, the second fiber Bragg grating and the third fiber Bragg grating are used for strain sensing, and the fourth fiber Bragg grating is used for temperature compensation.

Further, the inner conduit is provided with two rows of through holes, one end is hinged with the gripper head body, and the other end is threadedly connected with the driving handle; the two rows of through holes guide the four optical fibers to the optical fiber connector, and the optical fiber connection The device is placed in the rotating handle; the rotating handle adopts a symmetrical split structure, and the center and the upper part are provided with through holes to lead the optical fiber to the fiber grating demodulator; the fiber grating demodulator converts the collected optical signal into a force Signal, through the designed algorithm to achieve three-dimensional force decoupling.

Compared with prior art, the beneficial effect of the present invention is:

1) When laparoscopic grasping forceps are used to perform surgery, information on the force of instruments and tissues can be obtained, and the load applied to the handle can be controlled during the operation, so as to avoid slippage caused by too small clamping force and damage caused by excessive clamping force in existing operations Organization, improve the safety of laparoscopic surgery;

2) It adopts optical signal transmission, has high sensitivity and anti-electromagnetic interference, and can be used in MRI operation occasions where traditional electrical signal sensors cannot be applied.

Description of drawings

Fig. 1 is a schematic diagram of a laparoscopic three-dimensional force sensing grasper measurement system based on fiber Bragg gratings according to the present invention.

Fig. 2 is a schematic diagram of the body structure of the laparoscopic three-dimensional force sensing grasper based on fiber Bragg gratings according to the present invention.

Fig. 3 is a schematic diagram of the structure of the force sensing gripper head of the present invention.

Fig. 4 is a schematic diagram of the arrangement scheme of the fiber Bragg grating of the present invention.

Fig. 5 is an enlarged view of the tail structure of the three-dimensional force sensing grasper.

Fig. 6 is an enlarged view of the power drive structure of the three-dimensional force sensing grasper.

1—three-dimensional force sensing gripper body; 2—fiber grating demodulator; 3—computer; 4—grasper head body; 4a—upper gripper head; 4b—lower gripper head; 5—inner catheter; 6— Outer casing; 7—rotating handle; 8—optical fiber connector; 9—holding handle; 10—pin connection; 11—wire rope; 11a—upper wire rope; 11b—lower wire rope; 12a—first fiber Bragg grating ; 12b - the second fiber Bragg grating; 13a - the third fiber Bragg grating; 13b - the fourth fiber Bragg grating; 14 - the driving slider in the grip handle; 15 - the fiber channel in the inner catheter.

detailed description

The present invention will be further described below in conjunction with drawings and embodiments.

Referring to Figure 1, it is a schematic diagram of a laparoscopic three-dimensional force sensing grasper measurement system, which includes: a three-dimensional force sensing grasper body 1, which interacts with human tissue to convert force signals into optical signal output; fiber grating demodulation The instrument 2 converts the above optical signal into a digital signal; the computer 3 converts the digital signal into the three-dimensional force of the interaction between the instrument and the tissue by using a pre-written program, and outputs it on the display.

2 is a schematic diagram of the body structure of the three-dimensional force sensing gripper in the present invention, including gripper head bodies 4a and 4b, inner conduit 5, outer sleeve 6, rotary handle 7, optical fiber connector 8, and grip handle 9. The grasper head body 4 is connected to the inner catheter 5 through a hinge, and can perform a closed movement to clamp tissue. The material used for the grasper head body 4 is a biopolymer material with a low elastic modulus. Fig. 3 and Fig. 4 are schematic diagrams of fiber grating embedded in the gripper head body 4, in which fiber gratings 12a, 12b, 13a and 13b are embedded. Among them, 12a, 12b, and 13a are used for strain sensing, and 13b is used for temperature compensation.

Referring to Figures 3 and 4, they are schematic diagrams of the fiber Bragg grating arrangement scheme of the present invention. The left and right sides of Fig. 4 are the XY cross-sectional views of the two gripper head bodies 4 respectively (rectangular dotted line in Fig. 3), and the length direction of the gripper head body is the Z axis. The fiber Bragg grating 12a is located in the neutral layer of the XZ and YZ sections of the instrument, and the fiber Bragg grating 12b is located in the neutral layer of the XZ section of the instrument, with a distance of 1.5mm from the fiber Bragg grating 12a. The fiber Bragg grating 13a is located in the neutral layer of the YZ section of the instrument, and the fiber Bragg grating 13b is an additional temperature compensation sensor, and the vertical distance from the fiber Bragg grating 13b is 1.5mm.

Referring to Fig. 4, according to the layout scheme of the fiber grating in the present invention, the relationship between the force applied by the tissue on the grasper and the optical signal output by the grasper can be deduced, and the specific derivation process of the algorithm expression is as follows:

When the gripper head body is subjected to three-dimensional force loads F _x , F _y , F _z , it will be deformed, resulting in strain at the FBG sensor. Let K _ij be the load wavelength coefficient of each fiber, and K _Ti be the temperature wavelength coefficient of each fiber. According to the arrangement scheme of the sensor, the relationship between the variation of the reflected wavelength of each FBG and the external load is:

Δλ ₄ =K _T4 ΔT

Δλ ₁ =K _1z F _z +K _T1 ΔT

Δλ ₂ =K _2z F _z +K _2x F _x +K _T2 ΔT

Δλ ₃ =K _3z F _z +K _3y F _y +K _T3 ΔT

Suppose K _T1 /K _T4 =α ₁ , K _T2 /K _T4 =α ₂ , and K _T3 /K _T4 =α ₃ , the above formulas can be transformed into:

Δλ ₁ -α ₁ Δλ ₄ =K _1z F _z

Δλ ₂ -α ₂ Δλ ₄ =K _2z F _z +K _2x F _x

Δλ ₃ -α ₃ Δλ ₄ =K _3z F _z +K _3y F _y

Written in matrix form: Δλ=KF

in:

Δλ＝[Δλ ₁ -α ₁ Δλ ₄ Δλ ₂ -α ₂ Δλ ₄ Δλ ₃ -α ₃ Δλ ₄ ] ^T

F＝[F _x F _y F _z ] ^T

Measure the sensor reflection wavelength offset through the demodulator, and the computer obtains the three-dimensional force through the following decoupling algorithm:

F＝K ^-1 Δλ

Figure 5 is an enlarged view of the structure of the tail of the three-dimensional force sensing grasper. The outer sleeve 6 is connected to the rotary handle 7 through threads, and the inner conduit 5 extends from the through hole of the outer sleeve 6, and is fixed to the driving slider 14 in the handle 9. even. The optical fiber is led out from the gripper head body 4, extends through the optical fiber channels 15a, 15b in the inner catheter 5, and is connected to the fiber grating demodulator 2 through the optical fiber connector 8 fixed on the rotary handle 7 to realize the collection of optical signals.

Referring to accompanying drawing 6, it is the enlarged view of the power drive structure of the three-dimensional force sensing gripper of the present invention, the tail of the gripper head body 4 is fixedly connected with the outer casing by steel wire ropes 11a, 11b, and the two ropes are crossed X-shaped. When the grip handle 9 is closed, the inner conduit 5 is driven forward by the drive slider 14 in the grip handle to generate a small displacement, and at this moment, the grasper head body 4a, 4b is dragged and closed by the wire rope 11; Holding the handle 9, the inner conduit 5 is driven backward by the driving slider 14, and at this moment, the gripper head body 4a, 4b is resisted by the wire rope 11 and opened.

Through the above-mentioned embodiments, the present invention has the following beneficial effects: the laparoscopic three-dimensional force sensing grasper based on fiber Bragg gratings provided by the present invention converts the force of instruments and tissues into optical signals, which are collected and designed by the fiber Bragg grating demodulator The computer algorithm is decoupled to obtain the three-dimensional force that the instrument acts on the tissue, which effectively reduces the risk of slipping when the clamping force is too small and damage to the tissue when the clamping force is too large in traditional laparoscopic surgery. The designed three-dimensional force sensing grasper can also be used in nuclear magnetic resonance surgery where traditional sensors cannot work due to the use of optical signal transmission.

The detailed descriptions listed above are only specific illustrations for possible implementations of the present invention. Therefore, if those skilled in the art are inspired by it, and without departing from the spirit and scope of the present invention, the laparoscopic grasper that uses fiber Bragg grating embedded to realize three-dimensional force sensing and decoupling shall belong to this invention. protection scope of the invention.

Claims (3)

1. A laparoscopic three-dimensional force sensing grasper based on fiber Bragg gratings, comprising: Force-sensing grasper head, used to clamp tissue and convert clamping force signal into fiber Bragg grating optical signal; The drive handle is used for external load application and converts the holding force into the closing force required by the force sensing gripper head; The connecting sleeve is used to connect the force sensing gripper head and the driving handle, and transmit the optical signal to the signal processing unit; The signal processing unit is used to convert the optical signal into a digital signal and display it; it is characterized in that: The driving handle includes a rotating handle (7), a grip handle (9) and a driving slider (14) arranged in the grip handle (9); The connecting sleeve includes an inner conduit (5) with two rows of parallel optical fiber channels, an outer casing (6) sheathed outside the inner conduit (5), an upper steel wire rope fixed in the outer casing (6) (11a) and lower wire rope (11b) and optical fiber connector (8); The force sensing gripper head includes a gripper head body (4) and four fiber Bragg gratings; The signal processing unit includes a fiber grating demodulator (2) and a computer (3); The pliers head body (4) is composed of an upper pliers head (4a) and a lower pliers head (4b). ) are hinged, and are respectively connected to one end of the outer sleeve (6) through the upper steel wire rope (11a) and the lower steel wire rope (11a), and the other end of the outer sleeve (6) is connected to the rotary handle (7) are connected, and the described inner conduit (5) extends from the outer casing (6) and is connected with the described drive slider (14); One end of the first fiber Bragg grating (12a) and the second fiber Bragg grating (12b) is embedded in the upper gripper head (4a), the third fiber Bragg grating (13a) and the fourth fiber Bragg grating (13b) ) is embedded in the lower gripper head (4b), the other end of the first fiber Bragg grating (12a) and the second fiber Bragg grating (12b) are connected with the third fiber Bragg grating (13a) and the fourth fiber The other end of the Bragg grating (13b) is respectively connected to one end of the optical fiber connector (8) through two rows of parallel optical fiber channels, and the other end of the optical fiber connector (8) is externally connected to the input end of the fiber grating demodulator (2). The output end of the fiber grating demodulator (2) is connected with the computer (3). 2. The laparoscopic three-dimensional force sensing grasper based on fiber Bragg gratings according to claim 1, characterized in that: the material of the grasper head body is a low elastic modulus biopolymer material. 3. The laparoscopic three-dimensional force sensing grasper based on Fiber Bragg Gratings according to claim 1, characterized in that: the first Fiber Bragg Grating (12a), the second Fiber Bragg Grating (12b) and The third fiber Bragg grating (13a) is used for strain sensing, and the fourth fiber Bragg grating (13b) is used for temperature compensation.