Electrode with pre-wired leads

An electrode assembly for use in medical applications including an electrode having a conductor, a lead wire, and a connector. The wire is attached to the conductor with the connector. The connector includes two portions which snap together, and one or both portions have a corrugated wire contacting surface. The wire is held in electrical contact with the conductor between the first and second portions of the connector.

TECHNICAL FIELD 
The present invention relates to electrical connections. More particularly, 
the present invention relates to the connection of medical dispersive 
electrodes to electronic devices, such as permanent lead wires. 
BACKGROUND OF THE INVENTION 
In many medical diagnostic and therapeutic procedures electrical signals 
are received by or delivered to a patient's body. The interface between 
medical equipment used in these procedures and the skin of the patient is 
usually an electrode. The electrode typically includes a conductor which 
is connected electrically to the medical equipment by one or more wires. 
Dispersive electrodes used to return the current used in electrosurgery 
from the body are typically made with two wires attached to respective 
tabs projecting from the conductor. With some of these electrodes, two 
conductors, each having a tab and being attached to a separate wire are 
adhered to a single backing. 
A known method of assembling this class of electrodes involves removing the 
insulation from the end of the wires, and stapling or riveting the wires 
to the conductor. The connections are then insulated such as by wrapping 
foam tape around them. Both of these operations are time consuming and 
labor intensive, increasing the cost of health care. Additionally, if 
attachment is not done properly, the assembly must be scrapped. 
U.S. Pat. No. 4,738,263 to Seebach et al. discloses a two part connector 
for providing an electrical connection between an electrode and lead 
wires. However, these wires are connected to the electrode and the 
connector with ring terminals which fit over posts on the connector. This 
increases the cost of parts and labor. 
SUMMARY OF THE INVENTION 
The present invention overcomes these problems with known systems for 
connecting electrodes to medical devices. The connector of the present 
invention connects an electrode having a conductor to one or more wires. 
The conductor is generally flat. The electrode also has a layer of 
conductive gel or adhesive contacting one side of the conductor, and has 
insulation contacting the other side of the conductor. The wires are 
insulated except at their ends. 
The connector has first and second portions, and at least the first portion 
has a corrugated wire contacting surface. The first and second portions 
may be two distinct parts, or may be physically joined by a hinge along 
one edge of each of the portions of the connector. A snap fitting secures 
the first portion to the second portion. The snap fitting can include a 
tab attached to one of the first and second portions and a slot attached 
to the other of the first and second portions wherein the tab and slot 
complementarily snap together. The wire is held in electrical contact with 
the conductor between the first and second portions of the connector. 
Where the second portion of the connector also has a corrugated wire 
contacting surface, this surface is preferably complementary to the 
corrugated wire contacting surface on the first portion. Additionally, a 
raised ridge may be fabricated on one portion of the connector to prevent 
the uninsulated portion of the wires in a two wire assembly from 
contacting each other.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
The electrode assembly of the present invention connects an electrode and a 
conductor such as wire using a connector. The electrode assembly is a 
medical dispersive electrode assembly which serves as the interface 
between medical equipment and the skin of a patient. In FIG. 1, the 
electrode assembly 10 is shown assembled. FIGS. 2, 3, and 4 illustrate the 
details of the electrode assembly 10 prior to assembly. The electrode 
assembly 10 includes an electrode 12 having a conductor 14 and connected 
to one or more wires 16, 18 by a connector 20. The conductor 14 is 
generally flat, and may be made of metal (e.g. aluminum or tin), or may be 
made of a polymeric sheet having a conductive coating. The making of an 
exemplary coating is discussed in coassigned U.S. Pat. No. 4,848,348 to 
Craighead, which is incorporated herein by reference. 
As shown, there are two wires, 16, 18, both of which terminate in two 
uninsulated ends 22. The conductor 14 of the electrode 12 is exposed along 
two tabs 24. Except for the tabs 24, one side of the conductor 14 is 
covered by an insulative backing 26 and the other side of the conductor 14 
is covered by a layer of conductive adhesive 28 or conductive gel for 
contact with the patient's skin. In preferred embodiments of the electrode 
assembly 10 the backing 26 extends laterally beyond the conductor 14 to 
protect the outside edge of the conductive adhesive 28. A skin adhesive 
may be used on the underside of the backing 26 generally surrounding the 
conductive adhesive 28 to improve the adhesion of the electrode assembly 
10 to the surface of the skin. A discussion of conductive adhesives and 
their use in medical electrodes can be found in coassigned U.S. Pat. No. 
4,848,353 to Engel, which is incorporated herein by reference. The 
connector 20 preferably is fabricated from a polymeric material, such as 
polycarbonate or polypropylene. Preferred methods of fabrication include 
machining and preferably injection molding. 
The connector 20 includes a first portion 30 and a second portion 32. The 
first and second portions 30, 32 may be fabricated in two distinct parts, 
or may be physically connected along one edge by a hinge 34. The first 
portion 30 has a first wire contacting surface 36 and the second portion 
32 has a second wire contacing surface 38. Both the first and second wire 
contacting surfaces 36, 38 are textured although in alternative 
embodiments only one surface could be textured. Preferably the texture 
includes corrugations 40 and the corrugated surfaces 36, 38 are 
complementary. The corrugated surfaces 36, 38 are adapted to grip the 
uninsulated ends 22 of the wires 16, 18 against the tabs 24 when the 
electrode assembly 10 is assembled. The corrugated surfaces 36, 38 provide 
sufficient gripping force to create good conductivity between the wires 
16, 18 and the conductor 14 and enable the connector 20 to withstand the 
required 89 N (20 lb) of pullout force. 
A raised ridge 42 may be fabricated on or attached to the first portion 30 
of the connector 20 to prevent the uninsulated ends 22 of the wires 16, 18 
in a two wire assembly from contacting each other. 
The connector 20 is secured around the wires 16, 18 and the conductor 14 by 
placing the uninsulated ends 22 of the wires 16, 18 against the tabs 24 of 
the conductor 14. The connector 20 is closed by pivoting the two portions 
30, 32 of the connector 20 relative to each other by bending the hinge 34 
so that the wire contacting surfaces 36 and 38 face each other and hold 
the wires 16, 18 in between. Several snap fittings secure the two portions 
30, 32 together. The snap fittings include female slots 44 formed on the 
first portion 30 and male tabs 46 formed on the second portion 32. The 
tabs 46 may include lips which hook through the slots 44. The snap 
fittings may be openable or permanently closed. Alternatively, various 
other latching arrangements can be used to connect the first and second 
portions 30, 32 of the connector 20. 
In FIG. 3, the complementary pattern of the corrugations are shown. 
Additionally, a projection 48 on the first portion 30 is adapted to engage 
an opening 50 on the second portion 32 when the portions are opposed to 
facilitate proper alignment during assembly and to assist the raised ridge 
42 in separating the wires 16, 18. Optionally, the connector 20 may have 
first and second necks 52, 54 on the first and second portions 30, 32, 
respectively, for supporting and gripping the insulated part of the wires 
16, 18. The necks 52, 54 may have corrugations 40 of their own to 
facilitate this function, and snap fittings may be used on the necks 52, 
54. 
In an alternative embodiment shown in FIG. 5, the first portion 30' of the 
connector 20' is shown. The straight raised ridge 42 is replaced with a 
V-shaped raised ridge 56 which directs the wires 16, 18 to their 
respective sides of the connector 20'. Additionally, test probe openings 
58 are formed in the first portion 30' to receive test probes which 
measure conductivity to determine whether the wires 16, 18 are properly 
located. 
The connector holds an otherwise unprepared lead wire against the conductor 
of the electrode. There is no need to secure a ring or other specialty 
terminals to the wires by crimping or otherwise and the wires need not be 
specially prepared. Also, as the connector can be snapped over the 
electrode tabs and the wires by hand or with a press, assembly is simpler 
and cheaper than using staples or rivets. Nor is any additional insulation 
required as the connector serves as an insulator. Additionally, unlike 
stapled or riveted assemblies, if mistakes or errors occur during 
fabrication or assembly, the connector can be disassembled and the damaged 
component is replaced or the fault is corrected, thereby reducing waste. 
Numerous characteristics, advantages, and embodiments of the invention have 
been described in detail in the foregoing description with reference to 
the accompanying drawings. However, the disclosure is illustrative only 
and the invention is not intended to be limited to the precise embodiments 
illustrated. Various changes and modifications may be effected therein by 
one skilled in the art without departing from the scope or spirit of the 
invention.