Electrosurgical system with uniformly enhanced electric field and minimal collateral damage

• US 20080027428A1
• Filed: 04/16/2007
• Published: 01/31/2008
• Est. Priority Date: 02/14/2003
• Status: Active Grant

• Current Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Original Assignee: Board of Trustees of the Leland Stanford Junior University (Stanford Management Co.)
• Inventors: Palanker, Daniel, Vankov, Alexander
• Granted Patent: US 7,736,361 B2
• Time in Patent Office: Days
• US Class Current: 606/45
• CPC Class Codes: A61B 18/1402 Probes for open surgery
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/1407 Loop

Abstract

The present invention is directed towards an electrosurgical cutting system. The system comprises an electrically conductive blade, having an uninsulated cutting edge that is surrounded by an insulator. A source of pulsed electrical energy may be coupled to the electrically conductive blade to provide a substantially uniform and highly enhanced electric field along a cutting portion of the blade edge. The blade may have a uniform rate of erosion during use, so that both the conductive metal edge and the surrounding insulation layer erode at approximately the same rate. Also described are methods of fabricating insulated cutting electrodes, particularly blade electrodes.

Claims

1. An electrosurgical blade for use with an electrosurgical power supply, the blade comprising:

an electrode having an insulated area and an exposed edge region, the exposed edge region having an exposed edge thickness of between about 1 μ

m and about 100 μ

m; and

a glass enamel or ceramic insulator layer extending at least partially along the length of the electrode, wherein the insulator layer abuts the exposed electrode edge region and surrounds the exposed electrode edge region, and wherein the insulator layer has a thickness between about half to about three times the thickness of the exposed electrode edge region.

2. The electrosurgical blade of claim 1, wherein the electrode comprises a metal selected from the group consisting of titanium, tantalum, molybdenum, tungsten and stainless steel.

3. The electrosurgical blade of claim 1, wherein the electrode is formed from a metal foil having a thickness of between about 10 μ

m to about 50 μ

m.

4. The electrosurgical blade of claim 1, wherein the glass enamel insulator comprises high temperature grade, lead-free enamel.

5. The electrosurgical blade of claim 1, wherein the insulated length is greater than about 0.1 mm.

6. The electrosurgical blade of claim 1, wherein the length of the exposed active electrode edge region is substantially straight.

7. The electrosurgical blade of claim 1, wherein the length of the exposed active electrode edge region is curved.

8. The electrosurgical blade of claim 1, wherein the electrosurgical blade forms a scoop having the exposed edge region disposed at the perimeter of the scoop.

9. The electrosurgical blade of claim 1, further comprising a handle interface configured to secure the electrosurgical blade to a handle so that the electrode may make electrical contact with the electrosurgical power supply.

10. The electrosurgical blade of claim 1, wherein the exposed edge region forms a shape selected from the group consisting of an L-shape, U-Shape, V-shape, O-shape, or a combination of these shapes.

11. The electrosurgical blade of claim 1, wherein the exposed edge region is configured to form a substantially uniform electrical field when power is supplied by the electrosurgical power supply.

12. An electrosurgical blade for use with an electrosurgical power supply, the blade comprising:

a planar electrode having an upper insulated surface and a lower insulated surface, and an exposed edge region, wherein the upper and lower surfaces extend from the exposed edge region by a length that is greater than about 100 μ

m, and wherein the upper and lower surfaces are separated from each other by an electrode thickness between about 10 μ

m and 100 μ

m over this length; and

a first insulation layer covering the upper surface, and a second insulation layer covering the lower surface, wherein the thickness of the first and second insulation layers are between about 0.5 and 3 times the electrode thickness therebetween.

13. The electrosurgical blade of claim 12, wherein the planar electrode is formed from a conductive metal foil selected from the group consisting of titanium, tantalum, molybdenum, tungsten and stainless steel foils.

14. The electrosurgical blade of claim 12, wherein the first and second insulation layers comprise a material having a softening point or melting point between about 400°

C. and 900°

C.

15. The electrosurgical blade of claim 12, wherein the first and second insulation layers comprise glass enamel.

16. The electrosurgical blade of claim 12, wherein the first and second insulation layers comprise a material selected from the group consisting of glass, ceramics, and plastics.

17. An electrosurgical blade for use with an electrosurgical power supply, the blade comprising:

an active electrode having an insulated length and an exposed edge region, the exposed edge region having an exposed edge thickness of between about 1 μ

m and about 100 μ

m; and

an insulator layer extending at least partially along the length of the active electrode, wherein the insulator layer abuts the exposed electrode edge region and surrounds the exposed electrode edge region, and wherein the insulator layer has a thickness between about half to about three times the thickness of the exposed electrode edge region;

wherein the at least a portion of the exposed edge and the surrounding insulator layer form an edge profile,

wherein the insulator layer and the active electrode edge region erode at approximately the same rate when the electrosurgical blade is activated by the electrosurgical power supply, substantially preserving the edge profile as the active electrode edge region and insulator layer are eroded.

18. The electrosurgical blade of claim 17, wherein the insulator layer comprises glass.

19. The electrosurgical blade of claim 17, wherein the insulator layer comprises lead-free enamel.

20. The electrosurgical blade of claim 17, wherein the active electrode is formed of a metal foil, wherein the metal is selected from the group consisting of titanium, tantalum, molybdenum, tungsten and stainless steel.

21. The electrosurgical blade of claim 17, wherein the electrode is formed from titanium foil that is approximately 15 μ

m thick.

22. The electrosurgical blade of claim 17 wherein the length is greater than about 0.1 mm.

23. The electrosurgical blade of claim 17, wherein the length of the exposed edge region is substantially straight.

24. The electrosurgical blade of claim 17, wherein the length of the exposed edge region is curved to form a shape selected from the group consisting of an L-shape, U-Shape, V-shape, O-shape, or a combination of these shapes.

25. The electrosurgical blade of claim 17, further comprising a handle interface configured to secure the electrosurgical blade to a handle so that the electrode may make electrical contact with the electrosurgical power supply.

26. A method of fabricating an electrosurgical blade comprising:

applying a thin coating of insulator to an electrode having an elongated edge region so that the edge region is covered by the insulator; and

removing the insulator from the edge region by applying electrical energy to the electrode to expose the elongated edge of the electrode.

27. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises applying a thin coating of insulator to a metal foil.

28. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises applying a thin coating of insulator to an electrode having an elongated edge with a thickness between about 1 μ

m and about 100 μ

m.

29. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises applying a thin coating of insulator to an electrode made of a metal selected from the group consisting of titanium, tantalum, molybdenum, tungsten and stainless steel.

30. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises applying a coating of insulator to the electrode at a thickness of between about half to about three times the thickness of the edge region of the electrode.

31. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises spraying the electrode with an insulating material.

32. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises dipping the edge region of the electrode into an insulating material.

33. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises heat-curing the insulator onto the electrode.

34. The method of claim 26, wherein the step of applying a thin coating of insulator to an electrode comprises applying a glass enamel to the electrode.

35. The method of claim 26, further comprises electrically connecting the electrode to a source of electrical energy.

36. The method of claim 26, wherein the step of removing the insulator from the edge region by applying electrical energy to the electrode comprises applying pulsed RF energy to the electrode.

37. The method of claim 26, wherein the step of removing the insulator from the edge region by applying electrical energy to the electrode comprises forming a plasma discharge at the elongated edge region of the electrode.

38. The method of claim 26, wherein the step of removing the insulator from the edge region by applying electrical energy to the electrode comprises forming a plasma discharge at the elongated edge region of the electrode immersed in conductive liquid medium.

39. A method of fabricating an electrosurgical blade comprising:

providing an electrode having an edge region sufficient to focus an applied electrical field, wherein the edge region has a thickness of less than about 200 μ

m;

applying a thin coating of insulator to electrode including the edge region; and

removing insulator from the edge region by applying pulsed electrical energy to the electrode to form an electrical discharge at the edge region of the electrode.

40. The method of claim 39, further comprising connecting the electrode to a source of electrical power.

41. The method of claim 39, wherein the step of providing an electrode comprises providing an electrode having an edge region with a thickness of less than 100 μ

m.

42. The method of claim 39, wherein the step of providing an electrode comprises providing an electrode formed of metal foil.

43. The method of claim 39, wherein the step of applying a thin coating of insulator comprises applying a thin coating of an insulator having a softening point or melting point below 800°

C.

44. The method of claim 39, wherein the step of applying a thin coating of insulator comprises applying a thin coating of a glass epoxy insulator.

45. The method of claim 39, wherein the step of removing insulator from the edge region comprises applying pulsed electrical energy to form a plasma discharge.

46. A method of fabricating an electrosurgical blade comprising:

providing an electrode having edge region that is less than about 200 μ

m thick;

applying a thin coating of glass to the edge region; and

removing the glass insulation from the edge region of the electrode by applying electrical energy to the electrode.