JPH0349743A - Shape memory actuator - Google Patents

Abstract

PURPOSE:To prevent a shape memory actuator from being easily deformed by external force by providing shape memory resin in contact with shape memory alloy and setting the temperature of the shape memory resin to recover the shape lower than the temperature of the shape memory alloy to recover the shape. CONSTITUTION:An expander 1 is composed of a coil 4, for which a wire composed of the shape memory alloy is spirally molded, and shape memory resin 5 to cover the coil 4. When the expander 1 is inserted into a narrow part 3 of a duct 2 by an endoscope and catheter or surgical treatment, next, heated sodium chloride injection is injected into the narrow part 3 of the duct 2 and the expander 1 is heated, the expander is expanded to a diameter as the initial memory shape and the narrow part 3 is spreaded from the inside. When heating is finished after the expander 1 is expanded, the temperature of the expander 1 is lowered to the body temperature and the coil 4 of the expander 1 is transformed from an austenite phase on a high temperature side to a martensite phase on a low temperature side and softened. However, since the temperature of the expander 1 is lowered less than the shape recovery temperature in the expanded state, shape memory resin 5 is turned from a rubber state on the high temperature side to a plastic state on the low temperature side and hardness is increased. Then the expanded state is maintained. Thus, the shape memory actuator is not easily deformed by the external force.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shape memory actuator used, for example, for expanding biological ducts or bending catheters.

[Prior Art] A shape memory actuator is used as an expander for expanding a constricted portion of a biological duct.

This shape memory actuator is generally made of shape memory alloy (
SMA), and for dilating a constricted part of a biological duct, for example, there has been a conventional dilator, for example,
4-46477, JP-A-64-17658, JP-A-63-264077 and JP-A-63-
No. 122450 is known.

The above-mentioned JP-A-64-46477 and JP-A-63-
No. 264077 discloses that an expander made of a shape memory alloy formed in a spiral shape is fitted into a small diameter portion at the tip of a catheter,
After inserting the catheter together with the dilator into the constricted portion of the biological duct, the dilator is expanded in the radial direction to secure the inner diameter of the duct.

Japanese Patent Application Laid-Open No. 64-17658 discloses that a shape memory alloy coil is provided in the catheter body, a sheath is fitted,
After the catheter is inserted into a constricted portion of a biological duct, the shape memory alloy coil is expanded in the radial direction to form a gap between the catheter body and the sheath through which fluid can flow.

Furthermore, JP-A-63-122450 discloses an artificial prosthesis material in which the outer periphery of a coiled core material made of a shape memory alloy is covered with a sheath layer made of a flexible material, and the material It is designed to expand to secure the inner diameter of the blood vessel.

[Problems to be Solved by the Invention] However, the shape memory actuator described above is rigid when the shape memory alloy is heated to change its shape, for example, expand in the radial direction, but at low temperatures (it becomes soft). However, there is a problem in that the expander is deformed by external force.In other words, the expander is heated to a shape recovery temperature or higher, and then cooled by body temperature to a temperature lower than the recovery temperature, causing the expander to soften. Therefore, there is a problem that the expanded dilator becomes narrowed again due to the reaction force from the narrowed portion.

This invention was made in view of the above-mentioned circumstances, and its purpose is to create a shape memory actuator that does not easily deform due to external force even if the temperature drops below the recovery temperature after changing to a memory shape on the high temperature side. It is about providing.

[Means and effects for solving the problem] In order to achieve the above object, the present invention provides a shape memory resin in contact with a shape memory alloy, and sets the shape recovery temperature of the shape memory resin to
The temperature is set to be below the shape recovery temperature of the shape memory alloy, and the shape is maintained by the shape memory resin even if the temperature becomes below the shape recovery temperature of the shape memory alloy.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIGS. 1 to 3 show a first embodiment, in which 1 is a dilator as a shape memory actuator, and 3 is a constricted part 2 of a duct 2 such as a bile duct, pancreatic duct, blood vessel or esophagus of a living body. The tube is inserted into the tube to dilate the stenosis 3. The extension device 1 is
Coil 4 formed from a wire made of shape memory alloy into a spiral shape
and a shape memory resin 5 covering the coil 4.

The memorized shape of the coil 4 of the expansion device 1 is a shape expanded in the radial direction, as shown in FIG. The shape recovery temperature is also set at 40°C, which is higher than body temperature.

The operation of the expansion device 1 configured as described above will be explained. First, outside the body, under hot water or hot air at a shape recovery temperature of 40° C. or higher for the shape memory resin 5, the dilator 1 is formed into a coil shape so as to be reduced to a diameter that can be inserted into the constricted portion 3 of the conduit 2. do. Next, as shown in FIG.
The tube is inserted into the narrowed part 3 of the tube. Next, the narrowed part 3 of the pipe line 2
Warmed saline is injected into the dilator 1 using an endoscope or catheter, and the dilator 1 is heated. When the dilator 1 is heated, it expands to a diameter that is the initial memorized shape, and expands the constricted portion 3 from the inside. After the expansion device 1 is expanded and heating is finished,
The temperature of the dilator 1 decreases to body temperature, and the coil 4 of the dilator 1 cools down to body temperature.
transforms from the austenite phase on the high temperature side to the martensite phase on the low temperature side, and the coil 4 becomes soft. In other words, extension tool 1
is deformed by the reaction force from the constriction part 3, narrows again, and collapses. However, this expansion device 1 has a shape memory alloy coil 4.
Since the temperature of the shape memory resin 5 coated on the expanded state drops below the shape recovery temperature, the shape memory resin 5 changes from a rubber state at a high temperature to a plastic state at a low temperature, increasing in hardness and maintaining the expanded state. Therefore, even if the temperature of the dilator 1 drops to body temperature, the constricted portion 3 is maintained in an expanded state as shown in FIG. 2.

Note that in order to efficiently deform the expansion device 1 outside the body, if the shape recovery temperature of the coil 4 made of a shape memory alloy is 45°C and the shape memory resin 5 is 40°C, then
It becomes easier to deform under hot water or hot air, improving workability.

FIGS. 4 and 5 show a second embodiment, in which numeral 6 denotes a dilator as a shape memory actuator, which is a constricted part 3 of a duct 2 such as a living body's bile duct, pancreatic duct, blood vessel or esophagus. The tube is inserted into the tube to dilate the stenosis 3. Expansion device 6
Embodiment 1 is a coil 7 made of a wire material made of a shape memory alloy formed into a spiral shape, and a sheet 8 made of a shape memory resin that covers the outer periphery of the coil 7.The function is the same as that of the first embodiment. Therefore, the explanation will be omitted.

6 to 8 show a third embodiment, in which 9 is a catheter serving as a shape memory actuator. This catheter 9 is made of a shape memory resin and consists of a tube 11 having a channel 10 in the center and two wires 12, 13 made of a shape memory alloy arranged symmetrically inside the tube 11. In addition, both ends of these two wires 12 and 13 are connected to a power source 15 via a lead wire 14.
and the changeover switch 16.

The memorized shape of the wires 12 and 13 is an outwardly curved bow shape, as shown in FIG. 7, and the memorized shape of the tube 11 is a straight tube shape, as shown in FIG. be. Furthermore, the shape recovery temperature of the wires 12, 13 is set to above body temperature, for example, 45°C, and the tube 11
The shape recovery temperature of is set at 40°C.

Therefore, by operating the changeover switch 16, the wire 13
When heated with electricity, this wire 1.3 tends to curve outward. As the wire 13 is energized and heated, the catheter 9 curves downward into an arched shape, as shown in FIG. The heating temperature at this time was 45° C. for the wire 13 and 40° C. for the tube 11. Next, when the changeover switch 16 is set to the neutral point and the electrical heating of the wire 13 is stopped, the wire 13 is cooled by body temperature and becomes a softened state, but the tube 11 hardens into a plastic state and becomes curved. maintain.

In addition, in order to curve the catheter 9 in the opposite direction,
When the changeover switch 16 is operated to heat the wire 12 with electricity, the wire 12 is bent inward, and the tube 11 is heated and softened. For this reason, the catheter 9
is curved in the opposite direction to that shown in FIG. 7, that is, upward, and maintains its curved state. If it is desired to return the catheter 9 to its straight tube shape, both wires 12, 13 may be heated with electricity at the same time.

9 to 11 show a fourth embodiment, in which 14 is a stylet as a shape memory actuator.

This stylet 14 is composed of a stylet body 15 made of a shape memory resin, and one wire 16 made of a shape memory alloy embedded in the stylet body 15 in the axial direction. Also, this wire 16
Both ends are connected to a variable resistor 18 and a switch 19 via a lead wire 17.

The memorized shape of the stylet main body 15 is a straight shape as a whole, as shown in FIG. 9, and the memorized shape of the wire 16 is such that the distal end is curved into a hook shape, as shown in FIG. The end side has a straight shape, and the shape recovery temperature is 45°C for the wire 16 and 40°C for the stylet body 15.
It's Toshide.

Next, the operation of the stylet 14 configured as described above will be explained. As shown in FIGS. 10 and 11, the stylet 14 is inserted into the large intestine 20, and the variable resistance 18 is first adjusted so that 45"C>T>40°C, the stylet body 15 is softened, and the large intestine 20 is This can be easily inserted by using the channel of an endoscope (not shown) as a guide.When the distal end of the stylet body 15 reaches the entrance of the transverse colon,
T>45° C., and the wire 16 is restored to its recovered shape as shown in FIG. When the wire 16 restores its memorized shape, the stylet body 15 curves into a hook shape, and when the electrical heating to the wire 16 is then stopped, the wire 16 softens, but even at low temperatures, the stylet body 15 hardens. to maintain this shape. In addition, the stylet 14 is attached to the large intestine 2.
When removing the stylet from 0°C, by adjusting the variable resistor 18 so that 45°C>T>40°C, the stylet main body 15 can be softened and removed easily.

[Effects of the Invention] As explained above, according to the present invention, a shape memory resin is provided in contact with a shape memory alloy, and the shape recovery temperature of the shape memory resin is set to be equal to or lower than the shape recovery temperature of the shape memory alloy. Since the shape-memory resin maintains its shape even when the temperature drops below the shape-memory alloy's shape-recovery temperature, it does not easily deform due to external forces, and in order to maintain its shape, it can expand the narrowed part of the biological duct. Suitable for dilators, catheters, etc.

[Brief explanation of drawings]

1 to 3 show a dilator according to a first embodiment of the present invention; FIG. 1 is a perspective view of the dilator inserted into a constricted part of a biological duct, and FIG. 2 is a dilator with the constricted part expanded. FIG. 3 is a sectional view of the coil, FIGS. 4 and 5 show a second embodiment of the present invention, and FIG. 4 is a perspective view of the coil inserted into a constricted part of a biological duct. Figure 5 is a perspective view of the stenotic region expanded, Figures 6 to 8 show a third embodiment of the present invention, and Figure 6 is a perspective view of the catheter in a straight position. , FIG. 7 is a perspective view of the catheter in a curved state, and FIG. 8 is a perspective view of the catheter in a curved state.
The figure is a longitudinal side view of the catheter, Figures 9 to 11 show a fourth embodiment of the invention, and Figures 9 to 11 show a fifth embodiment of the invention. FIG. 9 is a longitudinal cross-sectional side view of the stylet, and FIGS. 10 and 11 are explanatory diagrams of the function of the stylet. 4... Coil (shape memory alloy) 5... Shape memory resin.

Claims (1)

[Claims] In a shape memory actuator that changes by heating a first shape at a low temperature and a second shape which is a memory shape at a high temperature side, a shape memory resin is provided in contact with a shape memory alloy,
A shape memory actuator characterized in that the shape recovery temperature of the shape memory resin is lower than the shape recovery temperature of the shape memory alloy.