Electrically-powered surgical systems for cutting and welding solid organs

1. A surgical system, comprising:

a surgical tool including a shaft and an end effector formed at a distal end thereof, the end effector having a clamping element and an ultrasonic blade, the clamping element being movable relative to the ultrasonic blade to clamp and treat tissue disposed between the clamping element and the ultrasonic blade;

a closure mechanism configured to selectively move the clamping element towards the ultrasonic blade from an open configuration to a closed configuration at a predetermined clamping velocity (v c ); and

a control system configured to:

maintain v c at a first clamping velocity (v c1 ) greater than a minimum clamping velocity (v min ) until a predetermined clamping force threshold (F o ) is achieved;

determine a closure parameter including at least one of an amount of time required to reach F o and an amount of displacement of the clamping element required to achieve F o ;

determine a tissue characteristic based upon the closure parameter; and

deliver energy to the ultrasonic blade to treat tissue in a feathering treatment according to a feathering treatment protocol based upon the determined tissue characteristic.

2. The system of claim 1 , wherein F o is a force resulting from contact of the clamping element with a tissue disposed between the clamping element and the ultrasonic blade.

3. The system of claim 1 , wherein the feathering treatment is effective to coagulate a tissue disposed between the clamp arm and the ultrasonic blade.

4. The system of claim 1 , wherein the tissue characteristic is a thickness of a tissue disposed between the clamping element and the ultrasonic blade.

5. The system of claim 4 , wherein the tissue thickness is less than a predetermined thickness and the control system is configured to operate in the feathering treatment protocol by:

maintaining v c at a third clamping velocity (v c3 ) while a clamping force applied to tissue disposed between the clamp arm and the ultrasonic blade is less than a predetermined second treatment force (F 2 ); and

decreasing v c from v c3 to a fourth clamping velocity (v c4 ) for the remainder of the feathering treatment in response to the clamping force rising to F 2 , wherein v c4 is configured to maintain the clamping force below F 2 .

6. The system of claim 5 , wherein v c3 and v c4 are each approximately constant.

7. The system of claim 4 , wherein the tissue thickness is greater than a predetermined thickness and the control system is configured to operate in the feathering treatment protocol by applying a clamping force to tissue disposed between the clamp arm and the ultrasonic blade at an approximately constant first treatment force (F 1 ).

8. The system of claim 7 , wherein the control system is configured to:

allow v c to decrease to a level approximately equal to v min ; and

increase the clamping force to a level between F 1 and a less than a second treatment force (F 2 ) for the remainder of the feathering treatment.

9. The system of claim 7 , wherein F 1 is based upon the determined tissue characteristic.

10. The system of claim 1 , further comprising an electrode configured to deliver radiofrequency energy to a tissue disposed between the clamping element and the ultrasonic blade.

11. The system of claim 10 , wherein the control system is configured to deliver at least one of ultrasonic energy to the ultrasonic blade and radiofrequency energy to the electrode according to a sealing treatment protocol occurring after the feathering treatment for coagulating and cutting a tissue disposed a tissue disposed between the clamping element and the ultrasonic blade.

12. The system of claim 11 , wherein the control system is further configured to perform the sealing treatment in response to detection that a preselected trigger condition is satisfied.

13. The system of claim 12 , wherein trigger condition is movement of the clamping element to a predetermined distance from the ultrasonic blade.

14. The system of claim 12 , wherein the trigger condition is deviation of v c from a velocity set point by a predetermined velocity threshold.

15. The system of claim 12 , wherein the trigger condition is application of a clamping force at a predefined amount of a maximum clamping force F max .

16. A method for treating tissue, comprising:

actuating a motor of a surgical tool including a shaft and an end effector, the end effector formed at a distal end of the shaft and having a clamping element and an ultrasonic blade coupled to an ultrasonic transducer, the clamping element being moveable relative to the ultrasonic blade to a tissue clamping position between an open position and a closed position of the clamping element at a predetermined clamping velocity (v c );

maintaining v c at a first clamping velocity (v c1 ) greater than a minimum clamping velocity (v min ) until a predetermined clamping force threshold (F o ) is achieved;

determining a closure parameter including at least one of an amount of time (t c ) required to reach F o and an amount of displacement of the clamping element δ c required to achieve F 0 ;

determining a tissue characteristic based upon the closure parameter; and

delivering energy to the ultrasonic blade to treat tissue in a feathering treatment according to a feathering treatment protocol based upon the determined tissue characteristic.

17. The method of claim 16 , wherein F o is a force resulting from contact of the clamping element with a tissue disposed between the clamping element and the ultrasonic blade.

18. The method of claim 16 , wherein the feathering treatment is effective to cauterize a tissue disposed between the clamp arm and the ultrasonic blade.

19. The method of claim 16 , wherein the tissue characteristic is a thickness of a tissue disposed between the clamping element and the ultrasonic blade.

20. The method of claim 19 , further comprising:

determining the tissue thickness to be less than a predetermined thickness;

maintaining v c at a third clamping velocity (v c3 ) while a clamping force applied to tissue disposed between the clamp arm and the ultrasonic blade is less than a predetermined second treatment force (F 2 ); and

decreasing v c from v c3 to a fourth clamping velocity (v c4 ) for the remainder of the feathering treatment in response to the clamping force rising to F 2 , wherein v c4 is configured to maintain the clamping force below F 2 .