Molded electrode

A conductive medical electrode formed from a moldable, conductive material such as carbon-filled plastic. In one embodiment, the electrode is an integral, conductive electrode including a stud adapted to detachably couple the electrode to a lead wire and a body integral with the stud. The body has a face disposed opposite the stud, for contacting a patient, which has a grooved pattern formed therein. The grooved pattern increases the surface area of the electrode in contact with a conductive adhesive and increases the conductivity between the patient and the electrode. A second embodiment features a two-piece, conductive electrode including an electrically conductive stud and an electrically conductive substrate having an opening formed therein and attached to the stud. The opening formed in the body creates a cavity which aids in retaining the conductive adhesive. The substrate has a face disposed opposite the stud, adapted to contact a patient, which has a grooved pattern formed therein. In a third embodiment, the conductive electrode includes a lead wire which is ultrasonically welded to the electrode body. Also provided is a method of manufacturing the integral, conductive electrode.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to medical electrodes that are used with a 
conductive adhesive and, in particular, to medical electrodes having a 
grooved pattern on a patient-contacting face that increases the surface 
area of the electrode in contact with the conductive adhesive. 
2. Description of the Related Art 
Medical electrodes are often used to monitor heart activity of a patient 
such as in electrocardiograph (ECG) applications. ECG electrode 
applications often require use of electrodes that are radiolucent to allow 
for continuous monitoring of the patient while x-ray or nuclear magnetic 
resonance (NMR) imaging is performed. Current radiolucent electrodes, like 
the Graphic Controls 2525 electrode and the ConMed ClearTrace electrode, 
have components that are made from carbonfilled plastics such as 
polyurethane, polyethylene, or acrylonitrile-butadiene-styrene (ABS) 
copolymer. Metals are eliminated because they will show-up on x-rays, 
whereas carbon does not show up at normal x-ray dose levels. 
Generally, an ECG electrode is made with a substrate material upon which 
other components are mounted. These other components include a stud and an 
eyelet that attaches the electrode to a wire coupled to an external 
monitor. Carbon-filled studs and eyelets cost more than the 
non-radiolucent metal varieties, are more difficult to assemble, often 
crack after joining by compression, experience a higher scrap rate due to 
production rejects, and are not as conductive as metal versions. To 
enhance conductivity, a silver/silver chloride coating is applied to the 
eyelet that is in contact with a conductive, adhesive gel that attaches 
the electrode to the patient. The silver/silver chloride coating enhances 
conductivity as well as other properties such as defibrillation recovery 
and DC offset, but increases costs due to the cost of the raw material and 
the cost of applying the silver/silver chloride coating to the electrode. 
SUMMARY OF THE INVENTION 
The present invention is a conductive medical electrode that can replace 
both conventional radiolucent electrodes and non-radiolucent electrodes. 
Unlike conventional electrodes that are assembled with various parts using 
automated machinery extensively, assembly of the electrode involves a 
small number of steps. The major part of the electrode that replaces the 
substrate, stud, and eyelet in conventional electrodes is made in one 
piece by a molding process. The electrode may be formed from a moldable, 
conductive material such as carbon-filled plastic. 
A first embodiment of the invention is an integral, conductive electrode 
including a stud adapted to detachably couple the electrode to a lead wire 
and a body integral with the stud. The body has a face disposed opposite 
the stud, for contacting a patient, which has a grooved pattern formed 
therein. The grooved pattern increases the surface area of the electrode 
in contact with the conductive adhesive and increases the conductivity 
between the patient and the electrode. 
A second embodiment of the invention is a two-piece, conductive electrode 
including an electrically conductive stud adapted to detachably couple the 
electrode to a lead wire and an electrically conductive substrate having 
an opening formed therein and attached to the stud. The opening formed in 
the substrate creates a cavity which aids in retaining a conductive 
adhesive. The substrate has a face disposed opposite the stud, for 
contacting a patient, which has a grooved pattern formed therein. 
In a third embodiment of the invention, the conductive electrode comprises 
an electrically conductive body having a face, for contacting a patient, 
which has a grooved pattern formed therein. A lead wire is ultrasonically 
welded to the electrode body.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 shows the conductive electrode 10 according to a first embodiment of 
the invention. The electrode 10 includes a stud 12 integral with a body 
14. The stud 12 and the body 14 are integrally formed in a molding process 
using conductive plastic. A lead wire with a conventional snap attachment 
(not shown) may be connected to the stud 12. The portion of the body 14 
away from the stud 12 is thin and pliable, allowing the electrode 10 to 
conform to the contours of a patient. The flat face 18 of the electrode 10 
is coated with a conductive adhesive 16. The conductive adhesive 16 may be 
a pressure-sensitive adhesive or a conductive, adhesive gel. The 
conductive adhesive 16 attaches the electrode 10 to the patient and 
conducts electrical signals to and from the patient. 
FIG. 2 is a top view of the electrode shown in FIG. 1. The electrode body 
14 has a large area so that the conductivity of the electrode 10 is 
significantly greater than that available with eyelets alone. The 
dimension of the electrode body 14 is significantly greater than the 
dimension of stud 12. In an exemplary embodiment, stud 12 has a diameter 
of 3.92 millimeters and body 14 has a diameter of 36.5 millimeters. This 
feature eliminates, in part, the need for a silver/silver chloride coating 
on the electrode 10. The electrode body 14 may be a variety of shapes such 
as oval, rectangular, square, or triangular as well as circular. 
As shown in FIGS. 3A and 3B, to further enhance conductivity, the flat face 
18 of the body 14 contains a grooved pattern 30 to increase the surface 
area of the flat face 18 in contact with the conductive adhesive 16 (shown 
in FIG. 1). FIG. 3 A illustrates a concentric pattern of grooves 30 which 
may be V-shaped as shown in FIG. 3B or curved as shown in FIG. 3C. FIG. 3D 
illustrates a checkerboard pattern of grooves 30 which also may be 
V-shaped or curved as shown in FIGS. 3E and 3F, respectively. For ease of 
illustration, FIGS. 3A-3F show a limited number of spaced grooves 30 
formed on the flat face 18. It is understood that a large number of 
grooves 30 may be formed in the flat face 18 and that adjacent grooves 30 
may be in close proximity to each other. It is also understood that a 
variety of groove patterns and groove profiles may be used to increase the 
surface area of the flat face 18 in contact with the conductive adhesive 
16. 
The electrode 10 shown in FIG. 1 may be made from carbon-filled plastics 
such as polyurethane, polyethylene, or acrylonitrile-butadiene-styrene 
(ABS) copolymer. The carbon-filled plastic may be radiolucent or 
non-radiolucent. A variety of molding processes may be used to manufacture 
the electrode 10, including injection molding, casting-type molding, 
thermal forming, and compression molding. For example, in injection 
molding the carbon-filled plastic is heated to a fluid state and forced 
under pressure through a runner system into a closed mold. The electrode 
10 is removed once the carbon-filled plastic has cooled and solidified. 
The mold includes ridges that form a grooved pattern, such as those shown 
in FIGS. 3A through 3F. In this way, the entire electrode 10 is formed in 
a single molding step which reduces costs. In addition, the reduction in 
the number of parts forming the electrode 10 reduces the scrap rate during 
manufacture. 
FIG. 4 illustrates a second embodiment of the present invention. Electrode 
20 includes a stud 22 integral with a base 26. The stud 22 and the base 26 
are made from a conductive plastic and formed through a molding process 
such as injection molding. Of course, other molding techniques may be used 
as discussed above. The base 26 is heat sealed to a substrate 24 which is 
also made from a conductive plastic. Substrate 24 is similar to the body 
14 (shown in FIG. 1) and includes a thin, pliable region away from the 
base 26 which allows the electrode 20 to conform to the contours of a 
patient. The outer dimension of the substrate 24 is larger than the outer 
dimension of the stud 22 to provide a large surface area in contact with 
the patient. Substrate 24 has a hole 25 formed therein. The base 26 
completely overlaps the hole 25 and forms a cavity which assists in 
retaining the conductive adhesive 16. The face 28 of the substrate 24 
includes a grooved pattern, such as those shown in FIGS. 3A through 3F. 
FIG. 5 illustrates a top view of the electrode 20 shown in FIG. 4. The 
substrate 24 may be any shape and is shown in FIG. 5 as rectangular. This 
allows the shape of the substrate 24 to be altered without changing the 
mold for the stud 22 and the base 26. To customize the electrode 20, only 
a new substrate 24 needs to be formed and heat sealed to base 26. Thus, 
the manufacturer can customize the electrode 20 to a user's needs without 
incurring large costs. 
FIG. 6 illustrates a variation of the stud 12 shown in FIG. 1 or the stud 
22 shown in FIG. 4. The stud 12 or the stud 22 includes a hollow region 62 
that provides for material relief Of course, this variation requires a 
more complex mold to manufacture. 
FIG. 7 illustrates a third embodiment of the present invention. The 
electrode 70 includes a weld area 72 integral with a body 74. The weld 
area 72 and body 74 are made from conductive plastic and are formed 
through a molding process such as injection molding. Of course, other 
molding techniques may be used as discussed above. Body 74 is similar to 
body 14 (shown in FIG. 1) and includes a thin, pliable region away from 
weld area 72 which allows the electrode 70 to conform to the contours of a 
patient. The face 78 of the body 74 includes a grooved pattern, such as 
those shown in FIGS. 3A through 3F. The weld area 72 receives a lead wire 
76 which is made of copper or carbon strands. The lead wire 76 is 
ultrasonically welded to weld area 72. A conductive adhesive 16 is applied 
to the bottom of the face 78 to attach the electrode 70 to the patient's 
skin and conduct electrical signals to and from the patient. 
It will be understood by one skilled in the art that many variations of the 
embodiments described herein are contemplated. Although the invention has 
been described in terms of exemplary embodiments, it is contemplated that 
it may be practiced as outlined above with modifications within the spirit 
and scope of the appended claims.