GB2549966A

GB2549966A - Electrode assembly

Info

Publication number: GB2549966A
Application number: GB1607806.5A
Authority: GB
Inventors: Wyn Morris David
Original assignee: Gyrus Medical Ltd
Current assignee: Gyrus Medical Ltd
Priority date: 2016-05-04
Filing date: 2016-05-04
Publication date: 2017-11-08
Anticipated expiration: 2036-05-04
Also published as: GB2549966B; GB201607806D0

Abstract

An electrode assembly for an electrosurgical instrument comprises an electrode body 5 having an electrode tip 4 and an elongate electrode stem 7. An insulating housing 3 has an elongate bore 13 formed therein, such that the electrode stem can be received within the bore with the electrode tip 4 extending from the distal end of the housing and a proximal portion 8 of the stem extending from the proximal end of the bore 13. During assembly, heat e.g. welding, is applied to the proximal portion of the stem to form it into a ball 15, the diameter of the ball being greater than that of the bore 13 such that it forms a mechanical stop preventing the electrode stem 7 from being moved distally with respect to the insulating housing.

Description

ELECTRODE ASSEMBLY

This invention relates to an electrode assembly for an electrosurgical instrument suitable for the treatment of tissue. Such instruments are commonly used for the vaporisation and/or coagulation of tissue in surgical intervention, most commonly in “keyhole” or minimally invasive surgery, but also in “open” surgery.

Electrosurgical instruments are growing in sophistication and complexity, with the number of electrodes increasing and the size of electrodes decreasing. One of the major factors in electrosurgical instrument design is the difficulty and complexity of instrument assembly, as well as the increased risk of components breaking or becoming detached during use. However, there is still a need for simple and efficient electrosurgical instruments provided that all safety and instrument reliability requirements are met. The present invention attempts to address this problem by providing a simple and efficient electrosurgical instrument, while still providing acceptable safety and reliability standards.

Accordingly, an electrode assembly for an electrosurgical instrument is provided, the electrode assembly comprising an electrode body having an electrode tip and an elongate electrode stem, an insulating housing having a proximal end and a distal end, the housing also having an elongate bore formed therein, such that the electrode stem can be received within the bore with the electrode tip extending from the distal end of the housing and a proximal portion of the stem extending from the proximal end of the bore, the proximal portion of the stem having been formed into a ball by heat applied to the proximal portion after it has been located within the bore, the diameter of the ball being greater than that of the bore such that it forms a mechanical stop preventing the electrode stem from being moved distally with respect to the insulating housing.

The formed ball prevents the electrode stem from moving distally within the bore, and hence secures the electrode in the insulating housing. Optionally, an adhesive can also be applied in order to further anchor the electrode stem within the housing. According to a preferred arrangement, the proximal portion of the stem is distal of the proximal end of the insulating housing. This means that the proximal portion of the stem terminates within the insulating housing, preventing the possibility of arcing between the stem and other electrically-conductive components within the instrument. In some instruments, the proximal area of the electrode assembly needs to be covered with an insulating sleeve or other insulating component in order to prevent such arcing, but with the present invention such a sleeve is merely optional.

Preferably, the insulating housing includes an outlet cavity into which the proximal end of the bore feeds. Typically, the outlet cavity extends to the proximal end of the insulating housing to allow access to the proximal end of the stem for the application of heat. In this way, access to the proximal end of the stem is achieved during assembly, yet the stem is contained within the insulating housing after assembly so as to avoid stray arcing.

The electrode assembly preferably includes an electrical lead attached to the electrode body at a location other than the proximal portion of the stem. The lead may be attached to the body of the electrode by various means, including soldering, welding or with the use of an electrically conductive adhesive. By separating the location of the lead from that of the stem used to retain the electrode within the housing, the electrode can be designed such that arcing from either the stem or the lead to other conductive components can be avoided. Preferably, the distal end of the lead is distal of the proximal end of the insulating housing. By locating both the stem and the area where the lead is attached well within the insulating housing, arcing is avoided and the requirement for additional insulting measures is reduced or avoided.

The invention further resides in a method of assembling an electrode assembly for an electrosurgical instrument including the steps of a) forming an electrode with an electrode tip and an elongate electrode stem, b) forming an insulating housing with a proximal end and a distal end, and having an elongate bore formed therethrough, c) presenting the electrode to the housing such that the electrode is temporarily located in the housing, with the electrode stem received within the bore and with the electrode tip extending from the distal end of the housing and a proximal portion of the stem extending from the bore, d) heating the proximal portion of the stem so as to cause it to melt and change its shape, thereby acting as a mechanical stop preventing the electrode stem from being moved distally with respect to the insulating housing.

As before, the heating step preferably causes the proximal portion of the stem to form into a ball. Typically, the heating step comprises electric arc welding, or laser welding. Once again, an adhesive is optionally added to further retain the stem within the housing. Again, the method preferably includes the further step of connecting an electrical lead to a portion of the electrode other than the proximal portion of the stem.

The invention will now be further described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a sectional view, generally from one side, of an electrode assembly in accordance with the present invention, in an initial stage of assembly

Figure 2 is a sectional view of the electrode assembly of Figure 1, in a subsequent stage of assembly,

Figure 3 is a plan view of the electrode of Figure 1, with an electric lead attached thereto, and

Figure 4 is a perspective view of the electrode of Figure 3, with internal features visible.

Referring to Figure 1, an electrode assembly for an electrosurgical instrument is shown generally at 1, and comprises a suction electrode 2 and an insulating housing 3. The electrode 2 comprises a planar tissue treatment tip 4 and an electrode body 5, the electrode having a suction lumen 6 therein leading to a plurality of suction apertures (not shown) in the tip 4. An elongate stem 7 extends rearwardly from the electrode body 5, the proximal end of the stem being designated at 8.

The insulating housing 3 has a proximal end 9 and a distal end 10, the tissue treatment tip 4 abutting the distal end 10 of the housing. The housing contains a chamber 11 into which the electrode body 5 can be received. The housing also includes a suction lumen 12 in communication with the lumen 6 within the electrode. The housing further includes a bore 13 within which the stem 7 can be received. The bore opens up into a cavity 14 which runs to the proximal end 9 of the housing. The stem 7 is of a length such that its proximal end 8 extends into the cavity 14.

Figure 1 shows an initial stage of assembly with the electrode 2 located within the housing 3 but as yet unsecured. To secure the electrode within the housing a heat delivering instrument such as an arc or laser welding tip (not shown) is inserted within the cavity 14 so as to apply intense heat to the proximal end 8 of the stem. The heat causes the end of the stem to melt, and form into a ball 15 as shown in Figure 2. The ball 15 formed by the heat source has a diameter larger than that of the bore 13, such that the stem 7 can no longer travel distally within the bore, thereby securing the electrode 2 within the insulating housing 3. The proximal features of the electrode 2, including the ball 15, are all contained within the interior of the insulating housing 3, such that there are no exposed parts which could lead to unwanted arcing. An adhesive (not shown) could be introduced into the proximal end of the bore to further insulate the stem from other conductive components within the instrument.

Figures 3 & 4 show the electrode 2 with an electric lead 16 attached thereto, the lead generally being connected before the electrode is introduced in to the housing 3. The lead 16 is introduced into a lumen 17 and secured, for example by laser welding, the welding being carried out through a side aperture 18. Once the electrode 2 is secured within the insulating housing 3, the area where the lead is attached is contained well within the housing, such that arcing from the exposed part of the lead is prevented. The part of the lead not contained within the housing 3 is covered with an insulating sleeve 19, and hence arcing is prevented from this area also.

Other embodiments will be apparent to those skilled in the art without departing from the scope of the present invention. The melting of the proximal end of the stem forms a mechanical stop to prevent the electrode being removed from the insulating housing in which it is housed.

Claims

1. An electrode assembly for an electrosurgical instrument, the electrode assembly comprising an electrode body having an electrode tip and an elongate electrode stem, an insulating housing having a proximal end and a distal end, the housing also having an elongate bore formed therein, such that the electrode stem can be received within the bore with the electrode tip extending from the distal end of the housing and a proximal portion of the stem extending from the proximal end of the bore, the proximal portion of the stem having been formed into a ball by heat applied to the proximal portion after it has been located within the bore, the diameter of the ball being greater than that of the bore such that it forms a mechanical stop preventing the electrode stem from being moved distally with respect to the insulating housing.

2. An electrode assembly according to claim 1, wherein the proximal portion of the stem is distal of the proximal end of the insulating housing.

3. An electrode assembly according to claim 2, wherein the insulating housing includes an outlet cavity into which the proximal end of the bore feeds.

4. An electrode assembly according to claim 3, wherein the outlet cavity extends to the proximal end of the insulating housing to allow access to the proximal end of the stem for the application of heat

5. An electrode assembly according to any preceding claim, including an electrical lead attached to the electrode body at a location other than the proximal portion of the stem.

6. An electrode assembly according to claim 5, wherein the distal end of the lead is distal of the proximal end of the insulating housing.

7. A method of assembling an electrode assembly for an electrosurgical instrument including the steps of a) forming an electrode with an electrode tip and an elongate electrode stem, b) forming an insulating housing with a proximal end and a distal end, and having an elongate bore formed therethrough, c) presenting the electrode to the housing such that the electrode is temporarily located in the housing, with the electrode stem received within the bore and with the electrode tip extending from the distal end of the housing and a proximal portion of the stem extending from the bore, d) heating the proximal portion of the stem so as to cause it to melt and change its shape, thereby acting as a mechanical stop preventing the electrode stem from being moved distally with respect to the insulating housing.

8. A method according to claim 7, wherein the heating step causes the proximal portion of the stem to form into a ball.

9. A method according to claim 7 or claim 8, wherein the heating step comprises electric arc welding.

10. A method according to claim 7 or claim 8, wherein the heating step comprises laser welding.

11. A method according to any of claims 7 to 10, including the further step of connecting an electrical lead to a portion of the electrode other than the proximal portion of the stem.