Electrosurgical jaw structure for controlled energy delivery

• US 6,929,644 B2
• Filed: 10/22/2001
• Issued: 08/16/2005
• Est. Priority Date: 10/22/2001
• Status: Expired due to Term

• Current Assignee: Ethicon Endo-Surgery, Inc. (Johnson & Johnson)
• Original Assignee: SurgRx, Inc. (Johnson & Johnson)
• Inventors: Shadduck, John H., Truckai, Csaba, Strul, Bruno, Baker, James A.
• Primary Examiner(s): Peffley, Michael
• Assistant Examiner(s): ROANE, AARON F
• Application Number:
  US10/032,867
• Publication Number:
  US 20030078577A1
• Time in Patent Office: 1,394 Days
• Field of Search: 606 49- 52
• US Class Current: 606/51
• CPC Class Codes: A61B 18/1442 Probes having pivoting end effectors, e.g. forceps
• CPC Class Codes: A61B 2018/00077 high, i.e. electrically conducting
• CPC Class Codes: A61B 2018/00083 low, i.e. electrically insulating
• CPC Class Codes: A61B 2018/00148 with metal
• CPC Class Codes: A61B 2018/0063 Sealing
• CPC Class Codes: A61B 2018/00809 measured thermochromatically

Abstract

A working end of a surgical instrument that carries first and second jaws for delivering energy to tissue. In a preferred embodiment, at least one jaw of the working end defines a tissue-engagement plane that contacts the targeted tissue. The cross-section of the engagement plane reveals that it defines a surface conductive portion that overlies a variably resistive matrix of a temperature-sensitive resistive material or a pressure-sensitive resistive material. An interior of the jaw carries a conductive material or electrode that is coupled to an Rf source and controller. In an exemplary embodiment, the variably resistive matrix can comprise a positive temperature coefficient (PTC) material, such as a ceramic, that is engineered to exhibit a dramatically increasing resistance (i.e., several orders of magnitude) above a specific temperature of the material. In use, the engagement plane will apply active Rf energy to captured tissue until the point in time that the variably resistive matrix is heated to its selected switching range. Thereafter, current flow from the conductive electrode through the engagement surface will be terminated due to the exponential increase in the resistance of variably resistive matrix to provide instant and automatic reduction of Rf energy application. Further, the variably resistive matrix can effectively function as a resistive electrode to thereafter conduct thermal energy to the engaged tissue volume. Thus, the jaw structure can automatically modulate the application of energy to tissue between active Rf heating and passive conductive heating of captured tissue to maintain a target temperature level.

Claims

1. A working end of a surgical instrument for delivering energy to tissue, comprising:

paired first and second jaw members moveable between an open position and a closed position; and

at least one jaw including an electrode, a first body portion comprising an electrically conductive material having a temperature-sensitive variable resistance for responding to the temperature of the tissue, and a second body portion of a conductive material coupled to an Rf voltage source, wherein the first body portion is disposed between the second body portion and the electrode to control the passage of electrical current from the second body portion to the electrode and wherein said at least one jaw defines a surface engagement plane for engaging tissue, said engagement plane carrying an exposed surface of said second body portion.

2. The working end of claim 1, said engagement plane carrying an exposed surface of said first body portion.

3. The working end of claim 1 wherein said first body portion comprises a ceramic composition.

4. The working end of claim 1, wherein said first body portion has an electrical resistance that increases with an increase in temperature thereof.

5. The working end of claim 1, wherein said first body portion has an electrical resistance that decreases with an increase in temperature thereof.

6. The working end of claim 1, wherein said first body portion defines a switching range at which its electrical resistance substantially increases or decreases in a selected temperature range.

7. The working end of claim 6 wherein said switching range falls between about 40°

C. and 200°

C.