Electrosurgical device and methods

1. A tissue segmentation device, comprising:

at least one active electrode;

a return electrode;

a mechanical force application mechanism;

a voltage sensor;

a current sensor; and

a controller configured to control a power output of the segmentation device, the controller comprising a processing component, responsive to the voltage sensor and the current sensor, configured to execute the following:

(a) derive a power factor of power applied to the at least one electrode; and

(b) responsive to the deriving a power factor, assign a circuit status to a circuit comprising the at least one electrode; wherein

IF (PF≈0) and ((Vrms/Irms)≧T), THEN the circuit status is “open”; and

IF (PF≈0) and ((Vrms/Irms)<T), THEN the circuit status is “short”; where

PF is the power factor;

Vrms is the root mean square of a voltage associated with the power applied to the at least one electrode;

Irms is the root mean square of a current associated with the power applied to the at least one electrode; and

T is a threshold value.

2. The device of claim 1 , wherein:

the mechanical force application mechanism is a constant force spring configured to cause the at least one electrode to apply a constant force to tissue; and

the device is configured to apply the power to the at least one electrode while applying the constant force.

3. The device of claim 1 , wherein the threshold value is dependent on a tissue type.

4. The device of claim 1 , wherein the threshold value is dependent on a cutting surface area of the at least one active electrode.

5. The device of claim 1 , wherein the processing device is further configured to execute the following:

compare a first rate of travel of the at least one active electrode to at least one of a rate of travel parameter, a second rate of travel of the at least one active electrode, or a first rate of travel of a second active electrode;

responsive to the comparing a first rate of travel, adjust a tissue segmentation control signal to effectuate a change in at least one of a voltage applied to the at least one active electrode, a current applied to the at least one active electrode, or a power applied to the at least one active electrode.

6. The device of claim 1 , wherein the processing device is further configured to execute the following:

compare a distance of travel of the at least one active electrode to an expected distance of travel parameter of the at least one active electrode; and

assign a segmentation status to the circuit comprising the at least one active electrode; wherein

if the circuit status is “open” and the distance of travel is equal to or greater than the expected distance of travel, then the segmentation status is “complete”.

7. The device of claim 1 , wherein the processing device is further configured to execute the following:

compare a distance of travel of the at least one active electrode to an expected distance of travel parameter of the at least one active electrode; and

assign a segmentation status to the circuit comprising the at least one active electrode; wherein

if the circuit status is “open” and the distance of travel is less than the expected distance of travel, then the segmentation status is “incomplete”.

8. The device of claim 1 , wherein the processing device is further configured to execute the following:

responsive to assigning a circuit status of “short”, adjust a tissue segmentation control signal to effectuate a change in power applied to the at least one active electrode.

9. The device of claim 1 , wherein:

the mechanical force application mechanism is configured to apply a cutting force to tissue abutting the at least one active electrode, the mechanical force application mechanism responsive to a tissue segmentation control signal from the controller; and

the processing device is further configured to execute the following:

(a) compare a first rate of travel of the at least one active electrode to at least one of a rate of travel parameter, a second rate of travel of the at least one active electrode, or a first rate of travel of a second active electrode; and

(b) responsive to the comparing a first rate of travel, adjust the tissue segmentation control signal to effectuate a change in the cutting force applied to the at least one active electrode by the mechanical force application mechanism.

10. The device of claim 1 , further comprising:

a temperature sensor for detecting a temperature of tissue being segmented; and wherein the controller is configured to execute the following:

responsive to an input from the temperature sensor, adjust a tissue segmentation control signal to effectuate a change in at least one of a voltage applied to the at least one active electrode, a current applied to the at least one active electrode, or a power applied to the at least one active electrode.

11. The device of claim 1 , further comprising:

a force sensor for detecting a force being applied to tissue being segmented by the mechanical force application mechanism; and wherein

the controller is configured to execute the following:

responsive to an input from the force sensor, adjust a tissue segmentation control signal to effectuate a change in at least one of a voltage applied to the at least one active electrode, a current applied to the at least one active electrode, or a power applied to the at least one active electrode.

12. The device of claim 1 , wherein:

the at least one active electrode is a flexible wire configured to form a loop at a distal end of the segmentation device; and

the mechanical force application mechanism is a spring configured to bias the at least one active electrode towards a proximal end of the segmentation device.

13. A controller for a tissue segmentation device having at least one active electrode, a return electrode, a voltage sensor, a current sensor, and a mechanical force application mechanism, the controller comprising:

a processing component, responsive to the voltage sensor and a current sensor, configured to execute the following:

derive a power factor of power applied to the at least one electrode; and

responsive to the deriving a power factor, assign a circuit status to a circuit comprising the at least one electrode; wherein

IF (PF≈0) and ((Vrms/Irms)≧T), THEN the circuit status is “open”; and

IF (PF≈0) and ((Vrms/Irms)<T), THEN the circuit status is “short”; where

PF is the power factor;

Vrms is the root mean square of a voltage associated with the power applied to the at least one electrode;

Irms is the root mean square of a current associated with the power applied to the at least one electrode; and

T is a threshold value.

14. The controller of claim 13 , wherein the mechanical force application mechanism comprises a constant force spring.

15. The controller of claim 14 , wherein the threshold value is dependent on a tissue type.

16. The controller of claim 13 , wherein the threshold value is dependent on a cutting surface area of the at least one active electrode.

17. The controller of claim 13 , wherein the processing device is further configured to execute the following:

compare a first rate of travel of the at least one active electrode to at least one of a rate of travel parameter, a second rate of travel of the at least one active electrode, or a first rate of travel of a second active electrode;

responsive to the comparing a first rate of travel, adjust a tissue segmentation control signal to effectuate a change in at least one of a voltage applied to the at least one active electrode, a current applied to the at least one active electrode, or a power applied to the at least one active electrode.

18. The controller of claim 13 , wherein the processing device is further configured to execute the following:

compare a distance of travel of the at least one active electrode to an expected distance of travel parameter of the at least one active electrode; and

assign a segmentation status to the circuit comprising the at least one active electrode; wherein

if the circuit status is “open” and the distance of travel equals the expected distance of travel, then the segmentation status is “complete”.

19. The controller of claim 13 , wherein the processing device is further configured to execute the following:

compare a distance of travel of the at least one active electrode to an expected distance of travel parameter of the at least one active electrode; and

assign a segmentation status to the circuit comprising the at least one active electrode; wherein

if the circuit status is “open” and the distance of travel is less than the expected distance of travel, then the segmentation status is “incomplete”.

20. The controller of claim 13 , wherein the processing device is further configured to execute the following:

responsive to assigning a circuit status of “short”, adjust a tissue segmentation control signal to effectuate a change in power applied to the at least one active electrode.

21. The controller of claim 13 , wherein:

the mechanical force application mechanism is configured to apply a cutting force to tissue abutting the at least one active electrode, the mechanical force application mechanism responsive to a tissue segmentation control signal from the controller; and

the processing device is further configured to execute the following:

(c) compare a first rate of travel of the at least one active electrode to at least one of a rate of travel parameter, a second rate of travel of the at least one active electrode, or a first rate of travel of a second active electrode; and

(d) responsive to the comparing a first rate of travel, adjust the tissue segmentation control signal to effectuate a change in the cutting force applied to the at least one active electrode by the mechanical force application mechanism.

22. The controller of claim 13 , wherein the processing device is further configured to execute the following:

responsive to an input from a temperature sensor, adjust a tissue segmentation control signal to effectuate a change in at least one of a voltage applied to the at least one active electrode, a current applied to the at least one active electrode, or a power applied to the at least one active electrode.

23. The controller of claim 13 , further comprising:

a force sensor for detecting a force being applied to tissue being segmented by the mechanical force application mechanism; and wherein

the controller is configured to execute the following:

responsive to an input from the force sensor, adjust a tissue segmentation control signal to effectuate a change in at least one of a voltage applied to the at least one active electrode, a current applied to the at least one active electrode, or a power applied to the at least one active electrode.

24. A method of tissue segmentation, comprising:

providing a tissue segmentation device having at least one active electrode, a return electrode, a mechanical force application mechanism, a voltage sensor, and a current sensor,

deriving a power factor of power applied to the at least one electrode; and

responsive to the deriving a power factor, assigning a circuit status to a circuit comprising the at least one electrode; wherein

IF (PF≈0) and ((Vrms/Irms)≧T), THEN the circuit status is “open”; and

IF (PF≈0) and ((Vrms/Irms)<T), THEN the circuit status is “short”; where

PF is the power factor;

Vrms is the root mean square of a voltage associated with the power applied to the at least one electrode;

Irms is the root mean square of a current associated with the power applied to the at least one electrode; and

T is a threshold value.

25. The method of claim 24 , wherein, the method comprises:

applying a mechanical cutting force to the at least one electrode while applying the power to the at least one electrode.

26. The method of claim 24 , wherein the threshold value is dependent on at least one of a tissue type or a cutting surface area of the at least one active electrode.

27. The method of claim 24 , further comprising:

comparing a first rate of travel of the at least one active electrode to at least one of a rate of travel parameter, a second rate of travel of the at least one active electrode, or a first rate of travel of a second active electrode;

responsive to the comparing a first rate of travel, adjusting a tissue segmentation control signal to effectuate a change in at least one of a voltage applied to the at least one active electrode, a current applied to the at least one active electrode, or a power applied to the at least one active electrode.

28. The method of claim 24 , further comprising:

comparing a distance of travel of the at least one active electrode to an expected distance of travel parameter of the at least one active electrode; and

assigning a segmentation status to the circuit comprising the at least one active electrode; wherein

if the circuit status is “open” and the distance of travel equals the expected distance of travel, then the segmentation status is “complete”.

29. The method of claim 24 , further comprising:

responsive to assigning a circuit status of “short”, adjusting a tissue segmentation control signal to effectuate a change in power applied to the at least one active electrode.

30. A tissue segmentation device, comprising:

at least one active electrode;

a return electrode;

a mechanical force application mechanism;

a voltage sensor;

a current sensor; and

a controller configured to control a power output of the segmentation device, the controller comprising a processing component, responsive to the voltage sensor and the current sensor, configured to execute the following:

(c) derive an impedance to power applied to the at least one electrode; and

(d) responsive to the deriving the impedance, assign a circuit status to a circuit comprising the at least one electrode; wherein

IF (Z>T 1 ), THEN the circuit status is “open”; and

IF (Z<T 2 ), THEN the circuit status is “short”; where

Z is the impedance;

T 1 is a first threshold value; and

T 2 is a second threshold different from the first threshold value.