Slip ring assembly for surgical instrument

1. A surgical instrument, comprising:

(a) a body assembly;

(b) a shaft assembly extending distally from the body assembly along a shaft axis, wherein the shaft assembly includes an outer tube configured to rotate relative to the body assembly about the shaft axis;

(c) an end effector at a distal end of the shaft assembly, wherein the end effector is operable to treat tissue; and

(d) a slip ring assembly configured to enable electrical communication between the shaft assembly and the body assembly while permitting relative rotation therebetween, wherein the slip ring assembly comprises:

(i) a first electrical contact supported by the outer tube, and

(ii) a second electrical contact positioned radially outward of the outer tube, wherein the first and second electrical contacts are electrically coupled together,

wherein the first electrical contact is configured to rotate with the outer tube about the shaft axis relative to the second electrical contact while the first and second electrical contacts remain electrically coupled.

2. The surgical instrument of claim 1 , wherein the slip ring assembly is disposed at a proximal end of the shaft assembly.

3. The surgical instrument of claim 1 , wherein the shaft assembly further comprises a nozzle, wherein the slip ring assembly is housed within the nozzle.

4. The surgical instrument of claim 1 , wherein the slip ring assembly further comprises a contact support structure that supports the second electrical contact, wherein the contact support structure is rotationally fixed relative to the body assembly.

5. The surgical instrument of claim 4 , wherein the shaft assembly includes a chassis that rotatably supports the outer tube, wherein the contact support structure is coupled to the chassis.

6. The surgical instrument of claim 5 , wherein the contact support structure extends distally from the chassis.

7. The surgical instrument of claim 4 , wherein the contact support structure comprises a sleeve, wherein the sleeve encircles the outer tube and the first electrical contact.

8. The surgical instrument of claim 1 , wherein one of the first electrical contact or the second electrical contact comprises a ring contact, wherein the other of the first electrical contact or the second electrical contact comprises a brush contact.

9. The surgical instrument of claim 8 , wherein the brush contact includes an angled distal edge, wherein the angled distal edge is configured to promote sliding engagement of the first contact with the second contact in a direction parallel to the shaft axis.

10. The surgical instrument of claim 1 , wherein the slip ring assembly includes a plurality of first electrical contacts spaced axially and supported by the outer tube, and a plurality of second electrical contacts spaced axially and positioned radially outward of the first electrical contacts, wherein the first electrical contacts are configured to rotate with the outer tube relative to the second electrical contacts while remaining electrically coupled with the second electrical contacts.

11. The surgical instrument of claim 10 , wherein the first electrical contacts are spaced apart with non-uniform axial spacing, wherein the second electrical contacts are spaced apart with non-uniform axial spacing.

12. The surgical instrument of claim 10 , wherein the slip ring assembly further comprises a contact support structure that supports the second electrical contacts, wherein each adjacent pair of the second electrical contacts is separated by an electrically insulating barrier.

13. The surgical instrument of claim 12 , wherein the electrically insulating barrier is defined by the contact support structure.

14. The surgical instrument of claim 12 , wherein the electrically insulating barrier comprises an electrically insulating element coupled to the contact support structure.

15. The surgical instrument of claim 1 , wherein the shaft assembly is configured to releasably attach to the body assembly, wherein the body assembly includes a first electrical connector, wherein the shaft assembly includes a second electrical connector configured to electrically couple with the first electrical connector when the shaft assembly is attached to the body assembly.

16. A surgical instrument, comprising:

(a) a body assembly;

(b) a shaft assembly extending distally from the body assembly along a shaft axis, wherein the shaft assembly includes an outer tube configured to rotate relative to the body assembly about the shaft axis;

(c) an end effector at a distal end of the shaft assembly, wherein the end effector is operable to treat tissue; and

(d) a slip ring assembly configured to enable electrical communication between the shaft assembly and the body assembly while permitting relative rotation therebetween, wherein the slip ring assembly comprises:

(i) a plurality of brush contacts spaced axially along the shaft axis, and

(ii) a plurality of ring contacts spaced axially along the shaft axis, wherein the ring contacts encircle and electrically couple with the brush contacts,

wherein one of the brush contacts or the ring contacts are configured to rotate with the outer tube about the shaft axis relative to the other of the brush contacts or the ring contacts while the brush contacts and the ring contacts remain electrically coupled.

17. The surgical instrument of claim 16 , wherein the brush contacts and the ring contacts are configured to electrically engage at a location radially outward of the outer tube.

18. The surgical instrument of claim 16 , wherein the brush contacts are supported by the outer tube, wherein the ring contacts are supported by a sleeve that encircles the outer tube.

19. A surgical instrument, comprising:

(a) a body assembly;

(b) a shaft assembly extending distally from the body assembly along a shaft axis, wherein the shaft assembly includes an outer tube configured to rotate relative to the body assembly about the shaft axis;

(c) an end effector at a distal end of the shaft assembly, wherein the end effector is operable to treat tissue; and

(d) a slip ring assembly configured to enable electrical communication between the shaft assembly and the body assembly while permitting relative rotation therebetween, wherein the slip ring assembly comprises:

(i) a plurality of brush contacts arranged axially, wherein the brush contacts are spaced apart with non-uniform axial spacing, and

(ii) a plurality of ring contacts arranged axially and configured to electrically couple with the brush contacts, wherein the ring contacts are spaced apart with non-uniform axial spacing,

wherein the non-uniform axial spacing of the contacts is configured to establish impedances that prevent electrical shorting between non-coupled pairs of the contacts in the presence of fluid,

wherein one of the brush contacts or the ring contacts are configured to rotate with the outer tube about the shaft axis relative to the other of the brush contacts or the ring contacts while the brush contacts and the ring contacts remain electrically coupled.

20. The surgical instrument of claim 19 , wherein the ring contacts include a pair of high-power ring contacts each having a first axial width and a pair of low-power ring contacts each having a second axial width smaller than the first axial width, wherein the high-power ring contacts are spaced apart by a first axial distance and the low-power ring contacts are spaced apart by a second axial distance smaller than the first axial distance.