A drug delivery mechanism based on infrared light control for surgical robots

Abstract

The present invention relates to the field of minimally invasive surgical robot assistance, and specifically is an infrared light-controlled drug delivery mechanism for a surgical robot, comprising a linear motor capable of controlling the robot to enter a body through a natural cavity by linear motion, a rotating motor provided on the linear motor and having the functions of a clamping and rotating mechanism and an adjustable clamping position, a drug delivery mechanism provided on the rotating motor and having variable stiffness controlled by infrared light, and a clamping switch fixed on the hollow shaft of the rotating motor by a 3D-printed bracket for changing the position of the clamping drug delivery mechanism. The present invention adopts an infrared light control mechanism, which is a safe and wireless control method. Infrared control firstly provides the mechanism with heating conditions, and when necessary, uses the high energy of infrared to increase the working temperature of the mechanism, controls the mechanism stiffness to switch the working mode, and realizes different functions.

Description

Technical Field

[0001] The invention relates to the field of minimally invasive surgical robot assistance, and in particular to a drug delivery mechanism based on infrared light control and oriented to a surgical robot. Background Art

[0002] Minimally invasive surgery is a major innovation in general surgery. It refers to surgery performed inside the body cavity using laparoscopes, thoracoscopes, and other medical devices and related equipment. Compared with traditional surgery, the most obvious advantages of minimally invasive surgery are small incisions, less pain, and faster recovery.

[0003] With the development of minimally invasive surgery, minimally invasive surgical robots have also received widespread attention. Minimally invasive surgical robots include surgical consoles, robotic arm systems, and imaging systems. The surgical console receives the surgeon's orders and transmits the operations to be performed to the robotic arm system and imaging system through computer programs. The robotic arm system includes a robotic arm, a power mechanism, and surgical instruments. The robotic arm controls the movement of surgical instruments and adjusts the position of the instruments; surgical instruments are inserted into the body for surgical operations; and the power mechanism drives the end effector of the surgical instruments to perform corresponding operations.

[0004] Traditional surgical instruments are large in size, high in rigidity, and complex in structure, which is not conducive to the smooth conduct of surgery and places high demands on doctors who perform surgical operations. Therefore, it is necessary to further simplify the structure of surgical instruments, reduce their size, and solve the problem of high rigidity. Summary of the invention

[0005] In order to solve the above problems, the present invention proposes a drug delivery mechanism based on infrared light control for a surgical robot.

[0006] A drug delivery mechanism based on infrared light control for a surgical robot, comprising a linear motor capable of controlling the robot to enter the body through a natural cavity by linear motion, a rotary motor with clamping and rotation functions and adjustable clamping position arranged on the linear motor, a drug delivery mechanism with variable stiffness controlled by infrared light arranged on the rotary motor, and a clamping switch fixed on the hollow shaft of the rotary motor by a 3D-printed bracket for changing the position of the clamping drug delivery mechanism.

[0007] The hollow shaft of the rotating motor and the clamping switch are in a straight line.

[0008] The drug delivery mechanism comprises a molten phase-change tip for carrying the drug to be delivered and an infrared controlled phase-change section which cooperates with the molten phase-change tip for controlling the change of the overall rigidity of the mechanism.

[0009] The molten phase change tip is composed of SMA and a multifunctional protective layer wrapped on its surface. The multifunctional protective layer adopts an electrostatic spinning structure which is convenient for protecting human tissue from damage by the tip of the mechanism, loading drugs and releasing drugs in a molten state.

[0010] The electrostatic spinning structure can be doped with magnetic particles for expanding the working space of the melting phase change tip and achieving fine-tuning of the position of the melting phase change tip.

[0011] The main material of the multifunctional protective layer is polycaprolactone with low melting point characteristics.

[0012] The SMA is made of nickel-titanium alloy wire with shape memory function.

[0013] The infrared controlled module segment is composed of SMA and the PDA coating on its surface. Under the control of infrared light, SMA, with the assistance of the PDA coating on its surface, converts the light energy of infrared light into heat energy, so that the temperature of SMA rises. When the temperature reaches A f When the temperature is above 0.1°, SMA will complete the austenite phase transformation. At this time, the elastic modulus of SMA increases and the stiffness of other parts increases.

[0014] The clamping function of the clamping switch is mainly realized by combining a hollow shaft stepping motor with a single output shaft with a relay. The plastic shell of the relay is removed to expose the internal electromagnetic system, which mainly includes an iron core, a coil, an armature, and a contact spring.

[0015] The beneficial effects of the present invention are as follows: the present invention adopts an infrared light control mechanism, which is a safe and wireless control method. Infrared control first provides the mechanism with heating conditions. When necessary, the high energy of infrared is used to increase the working temperature of the mechanism, switch the working mode, and realize different functions. The low melting point polymer material wrapped at the tip of the drug delivery mechanism, namely LMPM, is combined with SMA by electrostatic spinning. The loose and porous characteristics of the spinning structure are convenient for the storage and transportation of drugs. Another function of infrared control is to melt the LMPM at the tip. The melted LMPM is easy to be peeled off from the mechanism, so that the drug can be released at a fixed point. Furthermore, the LMPM at the tip plays a buffering role between the mechanism and the living tissue, further improving the safety of the mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] The present invention is further described below in conjunction with the accompanying drawings and embodiments.

[0017] Figure 1 It is a schematic diagram of the three-dimensional structure of the present invention;

[0018] Figure 2 It is a schematic diagram of the structure of the drug delivery mechanism of the present invention;

[0019] Figure 3 It is a schematic diagram of a partial cross-sectional structure of the drug delivery mechanism of the present invention. DETAILED DESCRIPTION

[0020] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further described below.

[0021] like Figures 1 to 3 As shown, a drug delivery mechanism based on infrared light control for a surgical robot includes a linear motor A capable of controlling the robot to enter the body through a natural cavity by linear motion, a rotary motor B with clamping and rotation functions and adjustable clamping position arranged on the linear motor A, a drug delivery mechanism D with variable stiffness controlled by infrared light arranged on the rotary motor B, and a clamping switch C fixed on the hollow shaft of the rotary motor B by a 3D printed bracket for changing the position of the clamping drug delivery mechanism D.

[0022] The present invention adopts an infrared light control mechanism, which is a safe and wireless control method. Infrared control first provides the mechanism with heating conditions. When necessary, the high energy of infrared is used to increase the working temperature of the mechanism, switch the working mode, and realize different functions: 1. Low stiffness, compliance, and non-invasive passive compliance movement mode in natural cavities. For example, compliance can be used to predefine the curvature of the robot to realize movement in complex curved pipes; 2. High stiffness, injectable, and drug-able precision operation surgical mode.

[0023] The present invention uses infrared light control to achieve variable stiffness of surgical instruments. The mechanism has two working modes.

[0024] 1. In the absence of infrared light control, the mechanism is in a low-stiffness, compliant, non-invasive passive compliant motion mode in a natural cavity. For example, compliance can be used to predefine the curvature of the end effector to achieve motion in a complex curved pipe.

[0025] 2. With infrared light control, the device is in a precise operation mode with high rigidity, injectability and drug delivery. The size of the device can reach sub-millimeter level and the structure is simple. Infrared light control can adjust the working mode of the device. On the other hand, infrared light can control the melting and falling of the drug-carrying structure at the tip of the device to achieve targeted drug delivery.

[0026] In terms of size, the diameter of the drug delivery mechanism can be controlled at the sub-millimeter level. The SMA wire used in the present invention has a diameter of 0.3 mm for a single wire, which is a size that is difficult to achieve for the end effector of the currently more advanced endoscopic surgical robot. It is suitable for cavities with complex structures and narrow spaces such as blood vessels, digestive tracts, and trachea.

[0027] The materials used in the present invention are all biocompatible materials with high safety. The structure of the mechanism is simple and the cost is low.

[0028] The hollow shaft of the rotating motor B and the clamping switch C are in a straight line.

[0029] The drug delivery mechanism D comprises a molten phase change tip 1 for carrying the drug to be delivered, and an infrared controlled phase change section 2 which cooperates with the molten phase change tip 1 to control the change of the overall stiffness of the mechanism.

[0030] The molten phase change tip 1 is composed of SMA 22 and a multifunctional protective layer 11 wrapped on its surface. The multifunctional protective layer 11 adopts an electrostatic spinning structure that is convenient for protecting human tissue from damage by the tip of the mechanism, loading drugs and releasing drugs in a molten state.

[0031] The multifunctional protective layer 11 is to give full play to the drug loading and releasing ability of the mechanism, and on the other hand, it plays a buffering and protective role. It can be understood that when the material and length are the same, the stiffness k of the rod is positively correlated with the cross-sectional area. The smaller the cross-sectional area, the smaller k and the greater the flexibility. However, on the other hand, the smaller the cross-sectional area, the greater the pressure at the tip of the SMA, which is easy to cause damage to the surrounding soft tissue when the mechanism moves in the body.

[0032] The main material of the multifunctional protective layer 11 is polycaprolactone with a low melting point, namely PCL. PCL is an organic high molecular polymer with good biocompatibility and has important applications in controlled-release drug carriers, cell and tissue culture medium frames. PCL is completely degradable in the body and has good biodegradability. The degradation products are CO2 and H2O. On the other hand, PCL is also very soft and easily soluble in a variety of polar organic solvents.

[0033] The structure of the multifunctional protective layer 11 is an electrospinning structure. PCL electrospinning is a loose and porous structure. The loose and porous structure has a large specific surface area, which can increase the adhesion between PCL and the SMA22 surface, so that PCL spinning can be wrapped and adsorbed on the SMA22 surface; on the other hand, the porous structure is convenient for loading and transporting drugs; the specific operation of the PCL electrospinning structure wrapping SMA22 is: during the electrospinning process, a uniformly rotating SMA22 wire is added to the electrostatic field. Due to the effect of the high-voltage electrostatic field, the SMA22 exposed to the electrostatic field will be wrapped with a layer of spinning structure. The spinning solution used is a PCL solution dissolved in acetone. During the spinning process, acetone flows out of the needle tube along with the spinning solution, and is volatilized due to a large area of ​​exposure to the air. Finally, the only substance wrapped on the SMA surface is PCL.

[0034] The SMA22 is made of nickel-titanium alloy wire with shape memory function.

[0035] Infrared light can control the change of the elastic modulus of the infrared controlled phase change section 2, which is also the main reason for the variable stiffness in the present invention. The molten phase change tip 1 is also controlled by infrared light. Infrared light has two effects on the tip: 1. Control the phase change of SMA22 under the multifunctional protective layer to enter the surgical mode; 2. Control the melting of the multifunctional protective layer 11 to facilitate the shedding of the protective layer and release the drug at a fixed point.

[0036] The electrospinning structure can be doped with magnetic particles for expanding the working space of the melting phase change tip 1 and achieving fine adjustment of the position of the melting phase change tip 1 .

[0037] The infrared controlled module segment 2 is composed of SMA 22 and a PDA coating 21 on its surface. Under the control of infrared light, SMA 22, with the assistance of the PDA coating 21 on the surface, converts the light energy of the infrared light into heat energy, so that the temperature of SMA 22 rises. When the temperature reaches A f When the temperature is above 5000 °C, SMA22 will complete the austenite phase transformation. At this time, the elastic modulus of SMA22 increases and the stiffness of other components increases.

[0038] The SMA22 wire diameter is 0.3mm, which belongs to the temperature-controlled SMA. It can be understood that the stiffness of the SMA22 wire is proportional to its cross-sectional area. The larger the cross-sectional area, the higher the stiffness of the SMA22 of the same length. Therefore, the SMA22 diameter is an important parameter for the present invention, and the diameter of the SMA22 directly determines the size range of the mechanism; the overall size of the mechanism is controlled at the submillimeter level. On the other hand, the stiffness range of the mechanism is determined, and SMA22 wires of various diameters on the market are purchased for stiffness testing. The hydrogel has a stiffness similar to that of human tissue. The hydrogel is used to simulate human tissue, and the SMA is used to perform puncture experiments on artificial tissues. Finally, the SMA22 wire with a diameter of 0.3mm is preferably selected, because the 0.3mm SMA22 wire is selected as the main body of the present invention. When the infrared lamp is turned off, the mechanism cannot pierce the artificial tissue, indicating that the mechanism will not pose a threat to human tissue when it moves, and has good passive compliance. After turning on the infrared lamp, the mechanism completes the switching of the working mode within tens of seconds, and accurately punctures the artificial tissue.

[0039] The martensite finish temperature of SMA22 is f About 30℃, austenite end temperature A f The PCL used in the multifunctional protective layer 11 is a low melting point polymer material LMPM, which has a melting point of 60°C. It is known that the normal body temperature of the human body is 37.5°C, between M f With A fThis indicates that the drug delivery mechanism can maintain low stiffness and passive compliance in the normal human body. Only when the external conditions change, the drug delivery mechanism rises to A f The above will change the working mode. The switching of the working mode of the drug delivery mechanism mainly relies on infrared light control, and the influence of the internal environment is small. On the other hand, the melting point of LMPM is higher than that of A f , but with A f This indicates that the drug delivery mechanism can melt the multifunctional protective layer in the surgical mode, thereby achieving drug delivery in the surgical mode. After the multifunctional protective layer is melted, a large number of pores in the spinning structure will disappear, promoting the release of the drug loaded in the pores.

[0040] The infrared light control mechanism is used to switch the working mode. Compared with other control methods, light control is an unconstrained control method. The infrared light source has high energy and is also a relatively safe light source for the human body. The drug delivery mechanism converts the energy of infrared light into heat energy to heat up the mechanism, which greatly improves the rigidity of the mechanism and realizes the switching of working modes. On the other hand, it helps to peel off the multifunctional protective layer from SMA22 to achieve targeted drug delivery.

[0041] In order to improve the photothermal response of SMA22, the surface of SMA is coated with polydopamine PDA nanoparticles. PDA is a commonly used photothermal filler that can convert light energy into heat energy and has a good photothermal effect. The advantages of PDA are that its synthetic raw materials are natural, low cost, simple preparation method, and PDA coating 21 can be applied to almost any material surface, not affected by the chemical properties of the material, so PDA coating 21 is widely used in various fields. The specific operation steps are: treat the surface of the purchased SMA material, polish SMA22 with 1000 mesh sandpaper and wipe with alcohol. Add 90mL of deionized water and 20mL of ethanol to a 250mL round-bottom beaker and mix the two. Continue to add 5mL of 28%-30% ammonia water and stir evenly at room temperature; then prepare 10mL of dopamine hydrochloride aqueous solution with a mass concentration of 50mg / mL, quickly add the dopamine hydrochloride aqueous solution to the above solution, and continue stirring. Finally, add the polished and wiped SMA to make it completely immersed in the solution, let the solution in the beaker fully contact with air for oxidation, and continue stirring for 24 hours.

[0042] When the molten phase change tip 1 of the drug delivery mechanism D reaches the designated point or near the designated point and needs to operate in this area, in this case, it is cumbersome to continuously adjust the position of the molten phase change tip 1 from the end of the mechanism. Each time the target point changes, it is necessary to start adjusting from the end position. The time required for the movement to be transmitted from the end to the tip is also long, and this method is not conducive to the fine adjustment of the end effector position. In addition, the overall movement of the mechanism will bring unnecessary and excessive burdens to the patient, causing the patient's discomfort to increase, so the molten phase change tip 1 is further adjusted to allow the tip to have flexible movement ability, and Fe3O4 magnetic particles are added to the PCL multifunctional protective layer 11 wrapped by the end effector. The specific steps are similar to the above-mentioned electrospinning process: 10% of the PCL spinning solution is replaced with an equal amount of PCL and Fe3O4 1:1 mixed spinning solution; then the SMA tip is wrapped with a PCL / Fe3O4 spinning film in the same way as PCL electrospinning; after the Fe3O4 particles are added, the multifunctional protective layer of the tip is magnetic. The magnetic field can be used to control the small swing of the tip.

[0043] Fe3O4 is commonly used in photothermal therapy as a photothermal agent. Ferroferric oxide particles have a certain photothermal effect. The multifunctional protective layer doped with Fe3O4 particles is easier to reach melting conditions, which reduces the difficulty of melting the protective layer and facilitates drug release.

[0044] The drug delivery mechanism D is deformed by infrared light, but cannot move by itself and needs to rely on external drive to control the overall movement of the drug delivery mechanism D. Motor A can control the robot to enter the body through the natural cavity. The motor A that controls the linear motion drives the rotating motor B above to move, so that the drug delivery mechanism D has freedom in linear and rotational directions.

[0045] The clamping function of the clamping switch C is mainly achieved by combining a hollow shaft stepper motor B with a single output shaft with a relay. The plastic shell of the relay is removed to expose the internal electromagnetic system. The electromagnetic system mainly includes an iron core, a coil, an armature, and a contact spring. When a certain voltage is applied to both ends of the coil, a certain current will flow through the coil, and an electromagnetic effect will be generated near the coil. The armature will be attracted by the electromagnetic force to overcome the tension of the spring and be sucked toward the iron core. The adsorption force of the armature and the iron core is sufficient to fix the drug delivery mechanism D so that the relative position does not shift.

[0046] The clamp switch C is fixed to the hollow shaft of the motor B through a 3D printed bracket, so that the clamp switch C and the hollow shaft are in a straight line. The drug delivery mechanism D passes through the hollow shaft between the armature and the iron core. The clamping function is to allow the drug delivery mechanism D to have rotational freedom. The rotating shaft of the motor B is hollow, and the hollow part can be used to place the drug delivery mechanism D, so that the motor B and the drug delivery mechanism D are in a nearly coaxial state, but at the same time their relative positions on the straight line can be moved, realizing the function of adjustable clamping position.

[0047] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions only describe the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A drug delivery mechanism based on infrared light control for a surgical robot, characterized in that: It includes a linear motor capable of controlling the robot to enter the body through a natural cavity by linear motion, a rotary motor with clamping and rotating functions and adjustable clamping position arranged on the linear motor, a drug delivery mechanism with variable stiffness controlled by infrared light arranged on the rotary motor, and a clamping switch fixed on the hollow shaft of the rotary motor by a 3D-printed bracket for changing the position of the clamping drug delivery mechanism; The drug delivery mechanism has two working modes: First, in the absence of infrared light control, the mechanism is in a low-stiffness, compliant, non-invasive passive compliant motion mode in the natural cavity; Second, under the control of infrared light, the surgical mode is in high-rigidity, injectable, and drug-delivery precise operation mode, and the infrared light can control the melting and shedding of the drug-carrying structure at the tip of the mechanism to achieve targeted drug delivery; The drug delivery mechanism comprises a molten phase change tip for carrying the drug to be administered, and an infrared controlled phase change segment for controlling the change of the overall stiffness of the mechanism in cooperation with the molten phase change tip; the molten phase change tip is composed of an SMA and a multifunctional protective layer wrapped on its surface, and the multifunctional protective layer adopts an electrostatic spinning structure that is convenient for protecting human tissue from damage by the tip of the mechanism, loading drugs and releasing drugs in a molten state; the SMA is composed of a nickel-titanium alloy wire with shape memory function; the material of the multifunctional protective layer includes polycaprolactone with a low melting point characteristic; the infrared controlled phase change segment is composed of an SMA and a PDA coating on its surface, and under the control of infrared light, the SMA, with the assistance of the surface PDA coating, converts the light energy of the infrared light into heat energy, so that the temperature of the SMA rises, and when the temperature reaches the austenite end temperature A f When the temperature is above 0.1°, SMA will complete the austenite phase transformation. At this time, the elastic modulus of SMA increases and the stiffness of other components increases.

2. The drug delivery mechanism based on infrared light control for a surgical robot according to claim 1, characterized in that: The hollow shaft of the rotating motor and the clamping switch are in a straight line.

3. The drug delivery mechanism based on infrared light control for a surgical robot according to claim 1, characterized in that: The electrostatic spinning structure can be doped with magnetic particles for expanding the working space of the melting phase change tip and achieving fine-tuning of the position of the melting phase change tip.

4. The drug delivery mechanism based on infrared light control for a surgical robot according to claim 1, characterized in that: The clamping function of the clamping switch is realized by combining a hollow shaft stepping motor with a single output shaft with a relay. The plastic shell of the relay is removed to expose the internal electromagnetic system, which includes an iron core, a coil, an armature, and a contact spring.

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