Abstract
An apparatus for gas-assisted electrosurgery having a gas-assisted electrosurgical probe comprising a tube and an electrode within said tube, wherein a distal end portion of said electrode extends from an opening at a distal end of said tube and an electrically insulating tip connected to a distal end of said electrode. The electrically insulating tip has a substantially hemispherical distal end portion having a radius r.sub.1 and a proximal portion having a circular cross-section and a central axis of a length l.sub.1, wherein l.sub.1>r.sub.1.
Claims
1. A probe for gas-assisted electrosurgery comprising: a gas-assisted electrosurgical probe comprising a tube and an electrode within said tube, wherein a distal end portion of said electrode extends from an opening at a distal end of said tube; an electrically insulating tip connected to the distal end of said electrode, said electrically insulating tip comprising: a substantially hemispherical ceramic distal end portion having a radius r.sub.c; and a proximal ceramic portion having a circular cross-section, a concave outer surface and a central axis of a length L.sub.1; wherein L.sub.1>r.sub.c.
2. The probe for gas-assisted electrosurgery according to claim 1, further comprising a fillet between said substantially distal end portion and said proximal portion.
3. The probe for gas-assisted electrosurgery according to claim 1, wherein said proximal portion has an outer surface having a plurality of portions with at least two of said plurality of portions having different outer radii of curvature.
4. The probe for gas-assisted electrosurgery according to claim 3, wherein said at least two radii of curvature decrease from a proximal end of said electrically insulating tip to said fillet.
5. The probe for gas-assisted electrosurgery according to claim 1, wherein said proximal portion has an outer surface having a varying radius of curvature.
6. The probe for gas-assisted electrosurgery according to claim 1, wherein said proximal portion has a proximal end having a circular cross-section with a radius r.sub.p and 1.2r.sub.p<L.sub.1.
7. The probe for gas-assisted electrosurgery according to claim 1, wherein said proximal portion has a proximal end having a circular cross-section with a radius r.sub.p and a distal end with a radius r.sub.d, wherein r.sub.d>2r.sub.p.
8. The probe for gas-assisted electrosurgery according to claim 1, wherein said proximal portion has a proximal end having a circular cross-section with a radius r.sub.p and a distal end with a radius r.sub.d, wherein
9. The probe for gas-assisted electrosurgery according to claim 1, wherein said proximal portion has a proximal end having a circular cross-section with a radius r.sub.p and a distal end with a radius r.sub.d, wherein
Description
BRIEF DESCRIPTION OF THE DRAWINGS
(1) For a more complete understanding of the present invention and the advantages thereof, reference is now made to the following description and the accompanying drawings, in which:
(2) FIG. 1A is a perspective view of an endoscopic probe for a gas-assisted electrosurgical device in accordance with a preferred embodiment of the present invention.
(3) FIG. 1B is a perspective view of a distal end of an endoscopic probe for a gas-assisted electrosurgical device in accordance with a preferred embodiment of the present invention.
(4) FIG. 1C is a side view of a distal end of an endoscopic probe for a gas-assisted electrosurgical device in accordance with a preferred embodiment of the present invention.
(5) FIG. 2A is a top perspective view of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(6) FIG. 2B is a bottom perspective view of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(7) FIG. 2C is a top view of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(8) FIG. 2D is a bottom view of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(9) FIG. 2E is a side view of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(10) FIG. 2F is a side cross-sectional view of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(11) FIG. 3 is a first side dimension view of a ceramic tip for a gas-assisted electrosurgical probe with dimensional references in accordance with a preferred embodiment of the present invention.
(12) FIG. 4 is a second side view of a ceramic tip for a gas-assisted electrosurgical probe with dimensional references in accordance with a preferred embodiment of the present invention.
(13) FIG. 5A is a top perspective view of an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(14) FIG. 5B is a bottom perspective view of an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(15) FIG. 5C is a top view of an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(16) FIG. 5D is a bottom view of an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(17) FIG. 5E is a side view of an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(18) FIG. 5F is a side cross-sectional view of an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe in accordance with a preferred embodiment of the present invention.
(19) FIG. 6 is a side dimension view of an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe with dimensional references in accordance with a preferred embodiment of the present invention.
(20) FIG. 7 is a bottom view of a ceramic tip an alternative embodiment of a ceramic tip for a gas-assisted electrosurgical probe with dimensional references in accordance with a preferred embodiment of the present invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
(21) As shown in FIGS. 1A-1C, the present invention relates to a probe for gas-assisted electrosurgery. The probe shown in FIG. 1 is for endoscopic use, but the present invention works equally well for other types of minimally invasive surgery, including but not limited to, laparoscopy and colonoscopy. An exemplary probe 100 has a plug 110, an elongated flexible tube 120 having a plurality of spaced markings 122 near its distal end, and electrode 130 and an electrically insulating tip 200, for example, a ceramic tip, on the end of the electrode. While a flexible tube 120 is shown in FIGS. 1A-1C, the present invention is by not limited to probes with flexible tubes as it works equally well with probes having rigid tubes.
(22) A first embodiment of a ceramic tip 200 in accordance with a preferred embodiment of the present invention is described with reference to FIGS. 2A-2F. The ceramic tip 200 has a distal portion 210, a proximal portion 220 and a fillet or rounded portion 230 in between the distal and proximal portions. The distal portion preferably is hemispherical in shape. The proximal end of the ceramic tip 200 has a flat circular portion 240, a fillet or rounded portion 242 and an opening 250 for receiving a distal end of an electrode. The opening 250 is a cylindrical channel 252 having a rounded end 254.
(23) As shown in FIG. 3, the hemispherical portion 210 above the plane identified by the line A-A has a surface 212 having a constant radius of curvature r.sub.c. The proximal portion 220 is conical in shape with its surface 222 having a plurality of different radiuses of curvature r.sub.1, r.sub.2, . . . r.sub.n. Preferably the radii of curvature comply with the relationship r.sub.1<r.sub.2<r.sub.n to provide improved flow of plasma from the opening at the distal end of the tube 120 and around the ceramic tip 200.
(24) As shown in FIG. 4, the length L.sub.1 of the central axis of the proximal portion 220 of the ceramic tip 200 (from the proximal end to the beginning of the fillet) is greater than the radius r.sub.c of the hemispherical distal end 220 of the ceramic tip 200. Preferably the length L.sub.1 is at least 20% larger than r.sub.c. In other words 1.2r.sub.c<L.sub.1.
(25) A second preferred embodiment of a ceramic tip in accordance with a preferred embodiment of the present invention is shown in FIGS. 5A-5F. The ceramic tip 500 has a distal portion 510, a proximal portion 520 and a fillet or rounded portion 530 in between the distal and proximal portions. The distal portion preferably is hemispherical in shape. The proximal end of the ceramic tip 500 has a flat circular portion 540 and an opening 550 for receiving a distal end of an electrode. Similar to opening 250 in the first embodiment, the opening 550 may be a cylindrical channel 552 having a rounded end 554. Note that in FIGS. 5A-5F the second embodiment is shown as not having a fillet or rounded edge similar to the fillet 242 in the first embodiment. Such a fillet or rounded edge certainly may be used in the second embodiment or may be excluded in the first embodiment.
(26) As shown in FIGS. 5E and 5F, the sides of the proximal portion 520 in the second embodiment are straight rather than curved and thus are not concave or convex. Such straight sides may be said to have an infinite radius of curvature. As shown in FIG. 6, the length L.sub.1 of the central axis of the proximal portion 520 of the ceramic tip 500 (from the point at which the hemispherical distal portion 510 would meet the straight proximal portion 520 absent the fillet 530) is greater than the radius r.sub.c of the hemispherical distal end portion 520 of the ceramic tip 500. Preferably the length L.sub.1 is at least 20% larger than r.sub.c. In other words 1.2r.sub.c<L.sub.1.
(27) As shown in FIG. 7, the radius r.sub.d of the distal portion 510 and the radius r.sub.p of the proximal portion along with the length L.sub.1 define the slope of the surface of the distal portion 520 as
(28)
Preferably, r.sub.d>2r.sub.p and
(29)
(30) While the present invention has been described as a ceramic tip, other electrically insulating materials may be used instead of a ceramic material. Thus, the tip of the present invention may be described as an electrically insulating tip for a gas-assisted electrosurgical probe.
(31) The foregoing description of the preferred embodiment of the invention has been presented for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise form disclosed, and modifications and variations are possible in light of the above teachings or may be acquired from practice of the invention. The embodiment was chosen and described in order to explain the principles of the invention and its practical application to enable one skilled in the art to utilize the invention in various embodiments as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the claims appended hereto, and their equivalents. The entirety of each of the aforementioned documents is incorporated by reference herein.
