Folded ultrasonic end effectors with increased active length

1. An end effector for use with an ultrasonic surgical instrument, comprising:

a body extending along a longitudinal axis comprising a proximal end and a distal end, the body comprising an outer surface that defines an inner portion, the proximal end of the body is configured to couple to an ultrasonic transducer configured to produce vibrations at a predetermined frequency and a predetermined amplitude; and

an extendable folded element having a predetermined length, the extendable folded element comprising a first end coupled to the distal end of the body and extending proximally along the longitudinal axis from the distal end of the body toward the proximal end of the body into the inner portion, the extendable folded element comprising a second free acoustic end;

wherein the extendable folded element and the outer surface of the body define a single substantially parallel acoustic path spanning the length of the extendable folded element.

2. The end effector of claim 1 , wherein the extendable folded element is extendable along the longitudinal axis.

3. The end effector of claim 1 , wherein the extendable folded element is slidably moveable along the longitudinal axis.

4. The end effector of claim 1 , wherein the extendable folded element is rotatably moveable about an axis that is perpendicular to the longitudinal axis.

5. The end effector of claim 1 , wherein the distal end of the body substantially coincides with a node, wherein the node is a location of minimum amplitude displacement, wherein the second free acoustic end of the folded element substantially coincides with an antinode, wherein the antinode is a location of maximum amplitude displacement, and wherein when the end effector is energized by the ultrasonic transducer, the distal end of the body substantially coinciding with the node remains stable and the second free acoustic end vibrates at the predetermined frequency and amplitude.

6. The end effector of claim 1 , wherein the distal end of the body is located in proximity to a node; and

wherein the second free acoustic end of the folded element is located in proximity to an antinode.

7. The end effector of claim 1 , wherein the distal end of the body substantially coincides with a first displacement region located between a node and an antinode; and

wherein the second free acoustic end of the folded element substantially coincides with a second displacement region located between a node and an antinode.

8. The end effector of claim 1 , wherein the body is configured as a tubular member and the extendable folded element is configured as a solid member.

9. The end effector of claim 1 , wherein the body comprises a solid portion at the proximal end and a hollow portion at the distal end, wherein the hollow portion defines a slot to receive the extendable folded element therein.

10. The end effector of claim 1 , wherein the outer surface of the body defines an active length that is greater than one quarter wavelength, wherein the active length is defined as a region that begins at the distal end of the body where amplitude displacement is at a minimum and extend proximally to a location where the amplitude displacement is one-half of a maximum amplitude displacement that occurs along the active length.

11. The end effector of claim 1 , wherein the longitudinal cross-sectional area of the body is substantially equal to the longitudinal cross-sectional area of the extendable folded element.

12. A surgical instrument, comprising:

a transducer configured to produce vibrations along a longitudinal axis at a predetermined frequency and a predetermined amplitude;

an end effector for use with an ultrasonic surgical instrument, comprising:

a body extending along a longitudinal axis comprising a proximal end and a distal end, the body comprising an outer surface that defines an inner portion, the proximal end of the body is configured to couple to an ultrasonic transducer configured to produce vibrations at a predetermined frequency and a predetermined amplitude; and

an extendable folded element having a predetermined length, the extendable folded element comprising a first end coupled to the distal end of the body and extending proximally along the longitudinal axis from the distal end of the body toward the proximal end of the body into the inner portion, the extendable folded element comprising a second free acoustic end;

wherein the extendable folded element and the outer surface of the body define a single substantially parallel acoustic path spanning the length of the folded element.

13. The surgical instrument of claim 12 , wherein the extendable folded element is extendable along the longitudinal axis.

14. The surgical instrument of claim 12 , wherein the extendable folded element is slidably moveable along the longitudinal axis.

15. The surgical instrument of claim 12 , wherein the extendable folded element is rotatably moveable about an axis that is perpendicular to the longitudinal axis.

16. The surgical instrument of claim 12 , wherein the body is configured as a tubular member and the extendable folded element is configured as a solid member.

17. The surgical instrument of claim 12 , wherein the body comprises a solid portion at the proximal end and a hollow portion at the distal end, wherein the hollow portion defines a slot to receive the extendable folded element therein.

18. The surgical instrument of claim 12 , wherein when the end effector is energized by the ultrasonic transducer, the outer surface of the body defines an active length that is greater than one quarter wavelength, wherein the active length is defined as a region that begins at the distal end of the body where amplitude displacement is at a minimum and extend proximally to a location where the amplitude displacement is one-half of a maximum amplitude displacement that occurs along the active length.

19. The surgical instrument of claim 12 , wherein the longitudinal cross-sectional area of the body is substantially equal to the longitudinal cross-sectional area of the folded element.