Electrosurgical instruments and systems including thermal cutting elements
An electrosurgical instrument includes an end effector assembly including first and second jaw members. At least one of the first or second jaw members is movable relative to the other from a spaced-apart position to an approximated position to grasp tissue therebetween. A thermal cutting wire is disposed on at least a portion of at least one of the first or second jaw members. The thermal cutting wire is configured for ferromagnetic heating to provide automatic Curie temperature control upon supply of an AC signal thereto. The thermal cutting wire may include a conductive core, an inner ferromagnetic coating disposed about the conductive core, and an outer ferromagnetic coating disposed about the inner ferromagnetic coating. The thermal cutting wire may alternatively or additionally include an exposed outer surface defining a roughness configured to facilitate attenuation during ferromagnetic heating.
1 . An electrosurgical instrument, comprising:
an end effector assembly, including:
a first jaw member and a second jaw member, at least one of the first jaw member or the second jaw member movable relative to the other from a spaced-apart position to an approximated position to grasp tissue between a first opposed tissue-treating surface and a second opposed tissue-treating surface of the first jaw member and the second jaw member, the first jaw member including:
a first thermal cutting wire portion defining a first end and extending distally along at least a portion of a length of the first opposed tissue-treating surface;
a second thermal cutting wire portion extending about a distal tip of the first jaw member and defining a second end, the first thermal cutting wire portion and the second thermal cutting wire portion each including a ferromagnetic coating, wherein an exposed outer surface of the ferromagnetic coating has a roughness configured to facilitate attenuation during ferromagnetic heating, the roughness measured as an average peak-to-trough distance, wherein a ratio of the roughness to a skin depth of at least one of the first thermal cutting wire portion or the second thermal cutting wire portion is at least 1:3; and
a third thermal cutting wire portion defining a third end, being electrically connected to the first thermal cutting wire portion and the second thermal cutting wire portion, and branching off from the first thermal cutting wire portion and the second thermal cutting wire portion, the third thermal cutting wire portion extending through an interior of the first jaw member;
wherein each of the first end, the second end, and the third end is adapted to connect to an energy source, enabling the first and second thermal cutting wire portions to be independently activatable allowing automatic Curie temperature control to each respective portion upon supply of an AC signal thereto.
2 . The electrosurgical instrument according to claim 1 , wherein the roughness is patterned.
3 . The electrosurgical instrument according to claim 1 , wherein the roughness is random.
4 . The electrosurgical instrument according to claim 1 , wherein the ratio of the roughness to the skin depth is between 2:1 and 3:1.
5 . The electrosurgical instrument according to claim 1 , wherein the ratio of the roughness to the skin depth is at least 2:1.
6 . The electrosurgical instrument according to claim 1 , wherein the ratio of the roughness to the skin depth is at least 1:1.
7 . The electrosurgical instrument according to claim 1 , wherein each of the first thermal cutting wire portion and the second thermal cutting wire portion includes a conductive core, an inner ferromagnetic coating disposed about the conductive core, and an outer ferromagnetic coating disposed about the inner ferromagnetic coating, and wherein the inner ferromagnetic coating defines a first thickness and the outer ferromagnetic coating defines a second, different thickness.
8 . The electrosurgical instrument according to claim 7 , wherein the first thickness is greater than the second thickness.
9 . The electrosurgical instrument according to claim 7 , wherein the inner ferromagnetic coating is formed from a first material and the outer ferromagnetic coating is formed from a second, different material.
10 . The electrosurgical instrument according to claim 9 , wherein the second material defines a relatively greater permeability compared to the first material.
11 . The electrosurgical instrument according to claim 9 , wherein the first material defines a relatively greater magnetic loss compared to the second material.
12 . The electrosurgical instrument according to claim 7 , wherein the inner ferromagnetic coating defines a first Curie temperature and the outer ferromagnetic coating defines a second Curie temperature different from the first Curie temperature.
13 . The electrosurgical instrument according to claim 12 , wherein the second Curie temperature is greater than the first Curie temperature.