TISSUE ABLATION SYSTEMS AND METHOD
Tissue is treated using a radiofrequency power supply connected to an applicator having a chamber filled with an electrically non-conductive gas surrounded by a thin dielectric wall. A radiofrequency voltage is applied at a level sufficient to ionize the gas into a plasma and to capacitively couple the ionized plasma with the tissue to deliver radiofrequency current to ablate or otherwise treat the tissue.
1 . A device for applying energy to tissue, said device comprising:
a dielectric wall configured to engage against tissue, the dielectric wall defining a chamber therein;
a gas delivery system configured to deliver an electrically non-conductive gas into the chamber;
a first electrode positioned to within the chamber and configured to contact the electrically non-conductive gas within the chamber;
a second electrode positioned exterior of the chamber; and
a power supply connected to apply a voltage between the first electrode and the second electrode sufficient to initiate ionization of the gas into a plasma completely contained within the chamber and separated from the tissue by the dielectric wall.
2 . The device of claim 1 , wherein the plasma is configured to be capacitively coupled across the dielectric wall and into the tissue.
3 . The device of claim 1 , wherein the gas delivery system is configured to provide a continuous flow of the electrically non-conductive gas into the chamber.
4 . The device of claim 3 , wherein the gas delivery system is configured to provide the gas at a flow rate of 5 ml/sec. to 30 ml/sec.
5 . The device of claim 1 , wherein the power supply is configured to apply a voltage of at least 100 volts.
6 . The device of claim 1 , wherein the dielectric wall is formed of a conformable silicone.
7 . The device of claim 1 , wherein the dielectric wall has a thickness in a range of 0.004 inches to 0.03 inches.
8 . The device of claim 1 , further comprising a frame within the chamber.
9 . The device of claim 8 , wherein the frame is expandable to open the dielectric wall.
10 . The device of claim 1 , further comprising an elongate shaft coupled to the dielectric wall.
11 . The device of claim 10 , wherein the gas delivery system includes a gas flow path through the elongate shaft to deliver gas into the chamber.
12 . The device of claim 1 , wherein the electrically non-conductive gas is argon.
13 . A device for applying energy to tissue, said device comprising:
a dielectric wall configured to engage against tissue, the dielectric wall defining a chamber therein;
a gas delivery system configured to deliver an electrically non-conductive gas into the chamber;
a first electrode positioned within the chamber;
a second electrode positioned exterior of the chamber;
a radiofrequency power supply connected to pass radiofrequency energy between the first electrode and the second electrode to initiate ionization of the gas into a plasma completely contained within the chamber and separated from the tissue by the dielectric wall; and
wherein the device is configured to ablate the tissue with the radiofrequency energy.
14 . The device of claim 13 , wherein the device is configured to ablate the tissue to a depth of 1 mm to 5 mm.
15 . The device of claim 13 , wherein the gas delivery system is configured to provide a continuous flow of the electrically non-conductive gas into the chamber.
16 . The device of claim 13 , further comprising a frame within the chamber.
17 . The device of claim 16 , wherein the frame is expandable to open the dielectric wall.
18 . The device of claim 13 , further comprising an elongate shaft coupled to the dielectric wall.
19 . The device of claim 18 , wherein the gas delivery system includes a gas flow path through the elongate shaft to deliver gas into the chamber.
20 . The device of claim 19 , wherein the electrically non-conductive gas is argon.