Surgical instruments with curved section
Various embodiments described herein are directed to ultrasonic blades. For example, an ultrasonic blade may comprise a proximally positioned straight section extending along a longitudinal axis and a distally positioned curved section coupled to the straight section and curved away from the longitudinal axis. The curved section may define a radius of curvature and subtend a first angle. A point of tangency between the curved section and the straight section may be positioned at either a node of the ultrasonic blade or an anti-node of the ultrasonic blade.
1. A surgical instrument comprising:
an ultrasonic blade, the ultrasonic blade comprising:
a proximally positioned straight section extending along a longitudinal axis; and
a distally positioned curved section coupled to the straight section and curved away from the longitudinal axis, wherein the curved section defines a radius of curvature, wherein the curved section subtends a first angle, and wherein a point of tangency between the curved section and the straight section is located at a predetermined position; and
wherein the radius of curvature of the curved section is described by:
radius
of
curvature
=
nc
π
4
θ
f
0
(
π
-
θ
2
)
0.5
;
wherein:
f 0 is a resonant frequency of the ultrasonic blade according to a first mode;
θ is the first angle;
n is a number of quarter wavelengths in the curved section at the first mode; and
c is a phase velocity of ultrasonic vibrations in the ultrasonic blade at the resonant frequency.
2. The surgical instrument of claim 1 , wherein the predetermined position is selected from the group consisting of a node of the ultrasonic blade and an anti-node of the ultrasonic blade and in between the node and the anti-node of the ultrasonic blade, and any combinations thereof.
3. The surgical instrument of claim 1 , wherein the curved section of the ultrasonic blade comprises two quarter wavelengths at a resonant frequency of the ultrasonic blade.
4. The surgical instrument of claim 3 , wherein a length of the curved section of the ultrasonic blade is greater than a distance between adjacent nodes on the straight section of the ultrasonic blade.
5. The surgical instrument of claim 1 , wherein the curved section of the ultrasonic blade comprises one quarter wavelength at a resonant frequency of the ultrasonic blade.
6. The surgical instrument of claim 1 , further comprising a shaft enclosing at least a portion of an end effector.
7. The surgical instrument of claim 1 , further comprising:
a shaft extending along the longitudinal axis, wherein:
the ultrasonic blade is positioned within the shaft,
the ultrasonic blade is translatable along the longitudinal axis relative to the shaft from a first position in which the distally positioned curved section extends from a distal end of the shaft to a second position in which the distally positioned curved section is at least partially contained within the shaft.
8. The surgical instrument of claim 7 , wherein the distally positioned curved section of the ultrasonic blade contacts an inner wall of the shaft when the distally positioned curved section is at least partially contained within the shaft.
9. The surgical instrument of claim 7 , wherein the shaft is fixed and the ultrasonic blade is translatable along the longitudinal axis relative to the shaft.
10. The surgical instrument of claim 7 , wherein the ultrasonic blade is fixed and the shaft is translatable along the longitudinal axis relative to the ultrasonic blade.
11. The surgical instrument of claim 7 , wherein the distally positioned curved section comprises a first curved section and a second curved section, and wherein the first curved section defines a first radius of curvature described by the radius of curvature and the second curved section defines a second radius of curvature described by the radius of curvature.
12. The surgical instrument of claim 11 , wherein the ultrasonic blade is resilient such that the second radius of curvature of the second curved section increases upon distal translation of the ultrasonic blade to the first position.
13. The surgical instrument of claim 11 , wherein a first direction of the first curved section opposes a second direction of the second curved section.
14. An ultrasonic blade comprising:
a proximally positioned straight section extending along a longitudinal axis; and
a distally positioned curved section coupled to the straight section and curved away from the longitudinal axis, wherein the curved section defines a radius of curvature, wherein the curved section subtends a first angle, and wherein a point of tangency between the curved section and the straight section is located at a predetermined position; and
wherein the radius of curvature of the curved section is described by:
radius
of
curvature
=
nc
π
4
θ
f
0
(
π
-
θ
2
)
0.5
;
wherein:
f 0 is a resonant frequency of the ultrasonic blade according to a first mode;
θ is the first angle;
n is a number of quarter wavelengths in the curved section at the first mode; and
c is a phase velocity of ultrasonic vibrations in the ultrasonic blade at the resonant frequency.
15. The ultrasonic blade of claim 14 , wherein the predetermined position is selected from the group consisting of a node of the ultrasonic blade and an anti-node of the ultrasonic blade and in between the node and the anti-node of the ultrasonic blade, and any combinations thereof.
16. The ultrasonic blade of claim 14 , wherein the curved section of the ultrasonic blade comprises two quarter wavelengths at a resonant frequency of the ultrasonic blade.
17. The ultrasonic blade of claim 16 , wherein a length of the curved section of the ultrasonic blade is greater than a distance between adjacent nodes on the straight section of the ultrasonic blade.
18. The ultrasonic blade of claim 14 , wherein the curved section of the ultrasonic blade comprises one quarter wavelength at a resonant frequency of the ultrasonic blade.
19. An asymmetric ultrasonic blade comprising:
a proximally positioned straight section extending along a longitudinal axis;
a distally positioned curved section coupled to the straight section and curved away from the longitudinal axis; and
a radius of curvature defined by the curved section, wherein the curved section subtends an angle and wherein the radius of curvature of the curved section is described by:
radius
of
curvature
=
nc
π
4
θ
f
0
(
π
-
θ
2
)
0.5
;
wherein:
f 0 is a resonant frequency of the asymmetric ultrasonic blade according to a first mode;
θ is the angle;
n is a number of quarter wavelengths in the curved section at the first mode; and
c is a phase velocity of ultrasonic vibrations in the asymmetric ultrasonic blade at the resonant frequency; and
wherein an intersection of the curved section and the straight section defines a point of tangency at a predefined location corresponding to a node or an anti-node of the asymmetric ultrasonic blade, wherein the node or anti-node is positioned at the point of tangency to guide vibration modes of the asymmetric ultrasonic blade substantially along the longitudinal axis.
20. The asymmetric ultrasonic blade of claim 19 , wherein the node and anti-node are positioned from each other at a distance, and wherein the distance is equivalent to a one quarter wavelength.
21. The asymmetric ultrasonic blade of claim 19 , wherein the position of the node and anti-node is determined by the radius of curvature of the curved section.
22. The asymmetric ultrasonic blade of claim 21 , wherein a distance between the node and anti-node is defined by the radius of curvature of the curved section and wherein an increase in the radius of curvature defines an increase in an active area of the asymmetric ultrasonic blade.
23. The asymmetric ultrasonic blade of claim 19 , wherein the radius of curvature and the subtended angle define a ratio of transverse displacement to longitudinal displacement at a proximal end of the straight section to define a balance of the asymmetric ultrasonic blade.
24. A curved ultrasonic blade comprising:
a curved section comprising a proximal first curved section and a distal second curved section;
wherein:
the proximal first curved section is positionable within a shaft extending along a longitudinal axis;
the curved ultrasonic blade is translatable along the longitudinal axis from a first position in which the distal second curved section is contained within the shaft to a second position in which at least a portion of the distal second curved section extends from a distal end of the shaft;
the proximal first curved section defines a first radius of curvature;
the distal second curved section defines a second radius of curvature;
the first and second radius of curvature of the curved ultrasonic blade are described by:
radius
of
curvature
=
nc
π
4
θ
f
0
(
π
-
θ
2
)
0.5
;
wherein:
f 0 is a resonant frequency of the curved ultrasonic blade;
θ is a subtended angle that is subtended by the curved section;
n is a number of quarter wavelengths in the curved section; and
c is a phase velocity of ultrasonic vibrations in the curved ultrasonic blade at the resonant frequency.
25. The curved ultrasonic blade of claim 24 , wherein the curved section is balanced to guide a vibration mode of the curved ultrasonic blade substantially along the longitudinal axis.
26. An ultrasonic blade comprising:
a proximally positioned straight section;
a distally positioned curved section; and
wherein:
the ultrasonic blade is translatable along a longitudinal axis relative to a shaft from a first position in which the curved section extends from a distal end of the shaft to a second position in which the curved section is at least partially contained within the shaft;
the shaft extends along the longitudinal axis;
the curved section defines a radius of curvature; and
the radius of curvature of the ultrasonic blade is described by:
radius
of
curvature
=
nc
π
4
θ
f
0
(
π
-
θ
2
)
0.5
;
wherein:
f 0 is a resonant frequency of the ultrasonic blade;
θ is a subtended angle that is subtended by the curved section;
n is a number of quarter wavelengths in the curved section; and
c is a phase velocity of ultrasonic vibrations in the ultrasonic blade at the resonant frequency.