Seal arrangements for ultrasonically powered surgical instruments

1. A method of manufacturing an ultrasonic surgical instrument, said method comprising:

providing an ultrasonic waveguide comprising a cutting member at a distal end thereof;

providing an ultrasonic transducer assembly;

providing a hollow sheath sized to receive the cutting member;

identifying a motionless node on the ultrasonic waveguide when the ultrasonic transducer assembly is driven at maximum current at a resonant frequency of the ultrasonic transducer assembly;

installing a seal on the waveguide at the motionless node, wherein the seal has an annular groove therein, wherein installing a seal comprises positioning a first annular seal portion at the motionless node on the ultrasonic waveguide such that a first axial seal portion and a second axial seal portion extend axially in opposite axial directions beyond the first annular seal portion, and wherein when the seal is compressed, contact between the seal and the waveguide is less than contact between the seal and the hollow sheath; and

forming a portion of the hollow sheath into said annular groove in the seal.

2. The method of claim 1 wherein said forming comprises crimping a portion of the hollow sheath into the annular groove in the seal.

3. The method of claim 2 wherein said crimping comprises crimping the portion of the hollow sheath in discrete annular locations into the annular groove in the seal.

4. The method of claim 1 , wherein said step of installing the seal comprises over-molding the seal onto the waveguide at the motionless node.

5. A method of manufacturing an ultrasonic surgical instrument, said method comprising:

providing an ultrasonic waveguide comprising a blade implement at a distal end thereof;

providing an ultrasonic transducer assembly;

attaching the ultrasonic waveguide to the ultrasonic transducer assembly;

providing a hollow sheath sized to at least partially extend around the blade implement;

identifying a motionless node on the ultrasonic waveguide when the ultrasonic transducer assembly is driven at maximum current at a resonant frequency of the ultrasonic transducer assembly; and

installing a seal on the waveguide at the motionless node, wherein the seal has an annular groove therein, wherein installing a seal comprises positioning a first annular seal portion at the motionless node on the waveguide such that a first axial seal portion and a second axial seal portion extend axially in opposite axial directions beyond the first annular seal portion, and wherein when compressed, the seal maintains a contact with the waveguide that is less than a contact with the hollow sheath.

6. The method of claim 5 , further comprising forming a portion of the hollow sheath into said annular groove in the seal at the motionless node.

7. The method of claim 5 , wherein step of installing the seal comprises over-molding the seal onto the waveguide at the motionless node.

8. A method of manufacturing an ultrasonic surgical instrument, said method comprising:

providing an ultrasonic waveguide comprising a blade implement at a distal end thereof;

providing an ultrasonic transducer assembly;

providing a hollow sheath sized to receive the blade implement;

identifying a motionless node on the ultrasonic waveguide when the ultrasonic transducer assembly is driven at maximum current at a resonant frequency of the ultrasonic transducer assembly; and

attaching a seal on the waveguide at the motionless node, wherein installing a seal comprises positioning a first annular seal portion at the motionless node on the waveguide such that a first axial seal portion and a second axial seal portion extend axially in opposite axial directions beyond the first annular seal portion, and wherein the seal is in greater contact with the hollow sheath than with the waveguide when the seal is compressed.

9. The method of claim 8 , wherein the seal has an annular groove, and wherein the method further comprises forming a portion of the hollow sheath into said annular groove in the seal at the motionless node.

10. The method of claim 8 , wherein said step of installing the seal comprises over-molding the seal onto the waveguide at the motionless node.