U.S. patent number 3,774,592 [Application Number 05/208,586] was granted by the patent office on 1973-11-27 for method for providing an improved body electrode electrical connection.
This patent grant is currently assigned to Xerox Corporation. Invention is credited to Roy J. Lahr.
United States Patent |
3,774,592 |
Lahr |
November 27, 1973 |
METHOD FOR PROVIDING AN IMPROVED BODY ELECTRODE ELECTRICAL
CONNECTION
Abstract
Method and apparatus for providing an improved electrical
connection between an electrode placed on the surface of the body
and the underlying tissue. The electrode, including an absorbent
pad saturated with a conductive material, is adhesively affixed to
the body surface. The elongated fibers of a brush are brought into
contact with the absorbent pad and, with an appropriate amount of
force applied to the brush, the fibers micro-puncture the body
surface, forcing the conductive material into microchannels beneath
the body surface fomed or enlarged by the fibers and into contact
with the underlying tissue.
Inventors: |
Lahr; Roy J. (Sierra Madre,
CA) |
Assignee: |
Xerox Corporation (Stamford,
CT)
|
Family
ID: |
22775140 |
Appl.
No.: |
05/208,586 |
Filed: |
December 16, 1971 |
Current U.S.
Class: |
600/392;
600/397 |
Current CPC
Class: |
A61B
5/325 (20210101); A61B 5/25 (20210101) |
Current International
Class: |
A61B
5/0408 (20060101); A61B 5/0402 (20060101); A61b
005/04 () |
Field of
Search: |
;128/2.1E,2.6E,416,417,418,404,410,411,DIG.4,405,2.1R,2.6R,416-418 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Gaudet; Richard A.
Assistant Examiner: Cohen; Lee S.
Claims
What is claimed is:
1. A method of providing an electrical connection between a body
electrode and the tissue beneath the surface of the human anatomy
comprising the steps of:
a. placing the body electrode in contact with the body surface,
said body electrode comprising a flexible tape having an adhesive
on the underside thereof, a layer of a porous, absorbant material
affixed to the flexible tape, and a conductive electrode in
overlying relationship with said layer, said layer being saturated
with an electrolytic solution, and
b. puncturing said layer and said body surface through the upper
surface of said flexible tape by a sharp object such that a portion
of said electrolytic solution is forced through the body surface
into contact with the tissue therebeneath, whereby an electrical
connection is made between the tissue and the conductive
electrode.
2. The method of claim 1 wherein said absorbant layer is saturated
with said electrolytic solution prior to said layer being placed in
contact with said body surface.
3. The method of claim 1 wherein said absorbant layer is saturated
with said electrolytic solution after said layer is placed in
contact with said body surface.
Description
BACKGROUND OF THE INVENTION
Many techniques have been developed in the prior art for
transferring electrical signals to and from a patient through the
use of body electrodes electrically connected to monitoring
apparatus by means of electrical wires or through radio telemetry.
The prior art body electrodes have been held in place on the
patient by various means, such as by hand, suction cups, straps,
adhesives, or the like.
For one reason or the other, these prior art techniques for
maintaining the electrodes in place on the patient have not been
satisfactory. For example, in those situations wherein the patient
is mobile and not confined to a limited area, a portable electrode
which is immediately active, preferably disposable, and easily
affixed to the body would be preferable to the prior art
electrodes. In addition, it is desired that the body electrode be
small, not noticeable, and cause no immediate or long term
discomfort to the patient.
In the area of electroencephalography, the prior art techniques for
detecting and recording brain waves have not been satisfactory. The
voltages found in the human scalp region are minute, typically
about 10-80 microvolts. In order to get reliable readings, a good
connection is necessary. However, a surface layer of dead cells,
dirt, etc. usually prevents a good electrical connection to the
ionic fluids of the underlying living tissue. Various methods are
presently used to establish good connection from the body electrode
to the living tissue, a good connection typically being less than
10,000 ohms resistance between points four inches or greater apart.
Typically, the surface layer is abraded off after cleansing with a
solution, such as acetone. The rubbing is vigorous, with abrasives
added to some solutions to assist the abrading. All solutions are
heavily conductive, so that when an electrode is placed over the
abraded area, the conductive gel or solution then provides the
ohmic connection between metallic electrodes and living tissue. To
keep the electrode in place, a common practice is to glue the
electrode in the desired area with, for example, water-soluble
cement. Obviously, this procedure is not particularly comfortable
for the patient. An alternately used technique is that in which a
sterilized microneedle is buried in the scalp tissue which provides
a good ohmic connection but which is obviously uncomfortable to the
patient.
It is therefore desired that a body electrode be provided which is
easily affixed to a patient, which provides a good electrical
connection to the living tissue underlying the surface layer of
skin and which is preferable disposable.
U. S. Pat. No. 3,085,577 issued to R. M. Berman et al, is an
example of a prior art body electrode which is small, inexpensive,
disposable and portable. The electrode comprises a flexible tape
having an adhesive material on its underside and an absorbant pad
and screening material affixed to the underside by a small rigid
annular member. The pad is saturated with a conductive paste and
the assembly is placed in contact with the body part. The
inflexibility of the screening, however, as pointed out in the
patent, produces a low electrical resistance contact between the
skin and the electrode, the swelling and associated redness
obviously will produce discomfort to the patient. Since the body
electrode of Berman et al measures the electrical activity on the
surface of the skin, the connection necessary to read the extremely
small voltages produced by the body is not completely satisfactory
due to the surface layer of dead cells, dirt, etc. Again, the usual
practice with the type of electrode shown in Berman et al is to
pre-abrade or utilize solvent chemicals which slowly dissolve the
dead cell layer.
SUMMARY OF THE PRESENT INVENTION
The present invention provides an improved method of employing a
body electrode for transferring electrical signals to and from the
living tissues underlying the surface of a body part. In
particular, the body electrode of the present invention comprises a
flexible tape having an adhesive material on its underside. An
absorbent pad, saturated with a conductive material, is located
substantially in the center of the tape. A conductive electrode is
affixed in contact with the absorbent pad on the upper side of the
tape. The body electrode is then positioned on the body part and a
stiff bristle brush is dabbed against the absorbent pad which is
saturated with a conductive gel. The bristles are forced through
the pad and through the non-conductive surface layer of the skin.
It is found that a good connection is made and that apparently
microchannels are established through the non-conductive skin layer
with sufficient gel penetration to get excellent conduction, i.e.
5,000 - 7,000 ohms. This dabbing action of the stiff bristles has
been found not to be painful and for practical purposes the
attendant can dab at the back of his hand to perceive what dabbing
force should be used which would not cause discomfort to the
patient. Several uses have shown that a good, reliable contact is
immediately made, viable over several hours.
It is a object of the present invention to provide a novel method
for providing a low electrical resistance contact between the
living tissue underlying the surface of a body part and an
electrode positioned on the body surface.
It is still a further object of the present invention to provide a
disposable body electrode and applicator pack for applying the body
electrode to a body part in a manner whereby excellent electrical
contact is achieved between the living tissue underlying the
surface of a body part and an electrode positioned on the body
surface.
DESCRIPTION OF THE DRAWINGS
For a better understanding of the invention as well as other
objects and features thereof, reference is made to the following
description which is to be read in conjunction with the
accompanying drawing wherein:
FIG. 1 is a perspective view of a preferred body electrode showing
a top view thereof;
FIG. 2 is a perspective view of the preferred body electrode of
FIG. 1 showing a bottom view thereof; and
FIG. 3(a) illustrates the body electrode as applied to the surface
of the body part and FIG. 3(b) is a general representation of the
microchannels formed in the body part with the conductive material
therein by the dabbing action of the brush member.
DESCRIPTION OF THE PREFERRED EMBODIMENT
Referring to FIG. 1, a perspective top view of the body electrode
10 is shown with peel off covers 12, 14 and 16 partially removed to
illustrate the components of the body electrode. A flexible tape 18
has an absorbent pad located substantially in the center of the
tape 18. The absorbent pad 20 is saturated with a conductive gel or
paste, such as sodium chloride containing mixtures known as
electrode paste or gel containing sodium chloride. A conductive
electrode 22, either the foil as shown or a wire mesh, is affixed
to the upper side of the tape 18 over the absorbent pad 20 with
adhesive, cement or other material. The electrode 22 provides an
electrode clip point whereby the body electrode is electrically
connected to electromedical apparatus (not shown).
A brush member 24, comprising a handle portion 26 and a plurality
of bristles 28, is associated with the body electrode 10 and
preferably is packaged therewith in an unitary, disposable
pack.
The bristles are preferably of a uniform length and are of a
medically-suitable stiff material such as stainless steel.
FIG. 2 is a perspective bottom view of the body electrode 10 with
peel off covers 14 and 16 partially open, the covers being affixed
to adhesive zones on the margins of the bottom of absorbent pad
20.
As shown schematically in FIG. 3(a), the present invention is
utilized in the following manner.
The attendant first places the gel saturated absorbent pad 20 in
the desired location on a body part, such as scalp 30. The
attendant then dabs the brush 24 against the gel saturated
absorbent pad 20, driving the bristles through the pad and through
the nonconductive portion of the upper scalp. It is believed that
microchannels 32, shown in FIG. 3(b), through the nonconductive
scalp layer are established with sufficient gel penetration to get
excellent conduction, i.e. typically 5,000-7,000 ohms. The dabbing
action of the stiff bristles is generally not painful and, in
practice, the attendant may dab at the back of the hand to
determine what force can be used without causing discomfort to the
patient. Numerous tests have shown that a good, reliable contact is
made, viable over several hours.
The bottom side of tape 18 is provided with a pressure sensitive
adhesive enabling the body electrode 10 to be attached to the skin
and be tightly retained in position despite various changes in body
curvature that may serve to flex the tape 10 into conformity with
the skin surface. Suitable adhesives for this purpose are now
available and commonly employed in self retaining bandages.
The pad material is of the class of material which provides a thin
porous absorbent pad such as cotton, gauze, or the like. The
characteristic of the selected material is such as to absorb and
retain an electrically conductive paste or gel that is applied
thereto.
The advantage of the present invention is that it is inexpensive
and that its construction makes it adaptable for disposable use.
The package contemplated by the present invention includes the body
electrode assembhy 10 and the brush 24 since the brush is needed to
force the gel material into contact with the living tissue
underlying the surface layer of skin. The adhesive layer enables
body electrode 10, with the associated peel-off covers, to be
easily applied to the skin without sticking to other items during
its handling. Before application to the skin, these layers are
easily removed to expose the adhesive surface therebeneath. The
conductive gel may be added to the pad 20 prior to the sealing of
the body electrode 10 and its associated brush 20 within its
individual wrappers or, alternately, it can be applied to the pad
20 after the peel-off layers are removed.
While the invention has been described with reference to its
preferred embodiment, it will be understood by those skilled in the
art that various changes may be made and equivalents substituted
for elements thereof without departing from the true spirit and
scope of the invention. In addition, many modifications may be made
to adapt a particular situation or material to the teachings of the
invention without departing from its essential teachings.
* * * * *