U.S. patent number 3,662,757 [Application Number 05/028,311] was granted by the patent office on 1972-05-16 for diathermy plate electrode.
This patent grant is currently assigned to Matburn (Holdings) Limited. Invention is credited to John Harold Blackett.
United States Patent |
3,662,757 |
Blackett |
May 16, 1972 |
DIATHERMY PLATE ELECTRODE
Abstract
This invention relates to a plate electrode for use in surgical
diathermy or electrosurgical apparatus. The electrode is a thin
flexible sheet of metal foil backed by a flexible film of plastics
material.
Inventors: |
Blackett; John Harold (London,
EN) |
Assignee: |
Matburn (Holdings) Limited
(London, EN)
|
Family
ID: |
10158528 |
Appl.
No.: |
05/028,311 |
Filed: |
April 14, 1970 |
Foreign Application Priority Data
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Apr 25, 1969 [GB] |
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21,180/69 |
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Current U.S.
Class: |
607/152;
174/117FF; 336/232 |
Current CPC
Class: |
A61N
1/04 (20130101) |
Current International
Class: |
A61N
1/04 (20060101); A61n 001/06 () |
Field of
Search: |
;128/416,2.6E,DIG.4,303.13 ;174/117FF,117F,117PC
;336/200,206,232 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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394,385 |
|
Apr 1924 |
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DD |
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371,553 |
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Jan 1907 |
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FR |
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Other References
Med. & Biol. Engineering, Vol. 7, pp. 341-343, Dec. 28,
1968..
|
Primary Examiner: Howell; Kyle L.
Claims
What we claim is:
1. A plate electrode device for use in surgery comprising a thin
flexible metal foil sheet electrode, a thin flexible plastic
electrically non-conductive backing superimposed on a face of said
metal foil sheet, a pair of transversely spaced, parallel,
longitudinally extending flexible metal foil band conductor leads
integrally formed at their inner ends in one piece with said metal
foil sheet and extendable therefrom, said conductor leads being
spaced from one another throughout their entire length, a thin
flexible electrically non-conductive backing superimposed on one
face of and joining said pair of metal foil bands and an
electrically insulating layer covering the other face of said
bands.
2. The plate electrode device of claim 1 wherein said sheet
electrode and bands are substantially coplanar and said pair of
bands are spirally wound about said electrode.
3. The plate electrode device of claim 2 wherein the confronting
edges of successive convolutions of said band pair are separably
joined.
4. The plate electrode device of claim 1 including electrical
coupling elements connected to the outer ends of said bands.
5. A plate electrode as claimed in claim 1, wherein the electrode
is of aluminum foil and the backing is of a polyester.
6. A plate electrode as claimed in claim 1 wherein the electrode is
of copper and the backing is of polyester.
Description
BACKGROUND OF THE INVENTION
Diathermy is a process by which heat is developed in the human body
by the passage of a high frequency alternating electric current. A
typical surgical diathermy apparatus has two electrodes. One of
these electrodes is called the active electrode and is the
electrode used for cutting and coagulating the tissue. This
electrode has a very small surface area and the current passing
from this electrode to the tissues has an intense heating effect.
The other electrode is necessary to complete the electrical circuit
and is termed the indifferent ground or plate electrode. This
electrode is much larger in area than the active electrode in order
to reduce the current intensity and therefore its heating effect.
In order to prevent the occurrence of burns, it is important that a
high proportion of the area of the plate electrode is maintained in
good electrical contact with the skin.
Plate electrodes are usually of lead or stainless steel which can
be moulded to conform to the sites of application to the patients,
usually the thighs. To maintain good contact with the skin, the
plate electrode is placed in a gauze bag and dipped in saline
solution before use. Conductive creams or jellies may also be used
in the case of stainless steel plates. When a lead plate has been
bent a number of times, it tends to become corrugated, so that the
larger area of contact is reduced to a number of ridges, and this
can lead to burns at the site of the plate electrode. Such burns
may be very serious.
The conventional plate electrodes also suffer from other
disadvantages. Thus, the connecting lead to the diathermy apparatus
has to be fitted on to the plate with a connector or attachment of
some sort, and this always involves the possibility of bad
electrical contact or breakage, which may also result in the
patient being burnt. The high thermal mass of the conventional
plates in particular large, thick lead plates, combined with the
cooling effect of the saline, can produce a serious fall in body
temperature in the treatment of infants and young children.
Furthermore, lead plates are very heavy, and there is always the
danger that they will slip out of place if not bound firmly to the
patient.
An object of the present invention is to provide a plate electrode
which avoids the disadvantages of known plate electrodes.
SUMMARY OF THE INVENTION
A plate electrode according to the present invention comprises a
thin and flexible sheet of metal foil backed by a flexible film of
plastics material. The thickness of the metal foil and the plastics
material is not important provided the laminated structure which
forms the plate electrode is flexible and has adequate strength.
Preferably, the electrode has at least two integral conductor leads
which are also of flexible metal foil backed by a flexible plastics
film. The conductive metal foil of the leads is covered with a
flexible insulating film except for terminal portions which can be
inserted in a connector which may be in the form of an adaptor.
The electrode may be of any shape, e.g., square, rectangular, or
circular. Different shapes may be more convenient for certain sites
on the body, and for different methods of attachment.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a plan view of an electrode according to the invention,
and
FIG. 2 is a section to a greatly exaggerated scale.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
An electrode 1 is of circular shape with a diameter of about 15
centimeters. The electrode consists of a thin, flexible and
conductive metal foil with a backing 2 of thin flexible plastics
material. Such an electrode has the great advantage over
conventional plate electrodes that it is very flexible and always
provides excellent electrical contact with the skin of the patient
over the whole surface area of the electrode. The electrode plate
is used dry, eliminating the need of saline contact solution or
jelly. The electrode is also very light in weight and may be easily
and securely fitted to the patient by means of an adhesive plaster
or a bandage or the like.
The metal foil 1 can be of any convenient conductive material. It
may, for example, be of copper or aluminum or stainless alloy. The
backing 2 may be of any suitable flexible plastics film such as
polyvinyl chloride, polyethylene, or a polyester such as that known
under the registered trade mark of Mylar.
The electrode is preferably provided with two integral flexible
conductor leads 3 or 4. More than two leads can be provided if
desired. Where two leads are provided, both leads are made of
flexible metal foil backed by flexible plastics film and the
conductive metal foil may have a covering 5 of insulating material.
The insulating covering 5 to the conductor lead may conveniently be
of any flexible plastics film material such as polyvinyl chloride,
polyethylene or a polyester, or it may be of a plastics coating
applied in liquid form.
The purpose of a second conductor lead is to enable the electrical
continuity of the plate electrode to be monitored continuously, by
passing a small electrical current down one of the conductors to
the plate electrode and back via the other conductor through a
current sensing circuit, which may be arranged to provide a warning
signal if there is a discontinuity in the plate circuit. This
current is a secondary current which is not in any way connected
with the high frequency diathermy current.
The leads 3 and 4 have terminal portions 6 and 7.
The plate electrode may be made by first producing a laminate
consisting of a flexible metal foil backed by the flexible plastics
material after which the electrode and, if desired, its lead is
produced simply by cutting it out of the laminated sheet. However,
the electrode and its lead are advantageously manufactured by
printed circuit techniques. For example the metal foil of the
laminate can be etched to the desired shape, after first covering
the required metal area with an etch resistant coating.
An advantage of using an etching technique instead of the
mechanical cutting is that as shown in the drawing, a border 8 of
non-conducting plastics material is left surrounding the metal foil
of the electrode and the integral lead. This provides an insulated
edge to the lead conductor or conductors to prevent accidental
contact with other apparatus or with the body of the patient.
It has been found both convenient and economical to produce the
conductor leads 3 and 4 in the form of a coil or coils surrounding
the plate electrode. In such a case, a portion of the plastics film
of the backing may extend between adjacent coils and may be cut in
a continuous spiral which upon extension forms a longitudinally
extending lead of sufficient length (approximately 2 meters) to
reach from the diathermy generator to the patient. Preferably
however, thin radial portions or "bridges" of the plastics film may
be left between adjacent turns sufficient to hold the coils in
position for packing, but which will break if pulled, to allow the
lead to be extended.
After the electrode and its lead has been produced in this manner,
they may be backed by a suitable material to keep the lead in
position for packing and storage purposes until the electrode is
required for use when the backing material is removed to allow the
leads to be extended.
* * * * *