U.S. patent number 3,795,239 [Application Number 05/177,231] was granted by the patent office on 1974-03-05 for electrochemical electrode with heating means.
This patent grant is currently assigned to Hoffmann-La Roche Inc.. Invention is credited to Patrick Eberhard, Konrad Hammacher, Wolfgang Mindt.
United States Patent |
3,795,239 |
Eberhard , et al. |
March 5, 1974 |
ELECTROCHEMICAL ELECTRODE WITH HEATING MEANS
Abstract
An electrode arrangement for application to a body surface for
bloodless measurement in connection with the concentration or the
partial pressure of a gas in the blood comprising a sensor unit
having a face member for body contact, and a heating unit coupled
to the sensor unit for transmitting to said face member a thermal
condition for thermal stimulation of the local blood circulation.
In a further embodiment, the sensor unit includes at the face
member a cover membrane permeable for a gas to be measured.
Inventors: |
Eberhard; Patrick (Basel,
CH), Hammacher; Konrad (Kaiseraugst, CH),
Mindt; Wolfgang (Therwill, CH) |
Assignee: |
Hoffmann-La Roche Inc. (Nutley,
NJ)
|
Family
ID: |
4401701 |
Appl.
No.: |
05/177,231 |
Filed: |
September 2, 1971 |
Foreign Application Priority Data
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Oct 1, 1970 [CH] |
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14544/70 |
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Current U.S.
Class: |
600/358; 204/408;
204/415; 204/403.06; 600/354 |
Current CPC
Class: |
G01N
27/404 (20130101); A61B 5/1477 (20130101); A61B
5/14542 (20130101) |
Current International
Class: |
A61B
5/00 (20060101); G01N 27/49 (20060101); A61b
005/00 () |
Field of
Search: |
;128/2E,2.1E,399,303.1
;324/3R ;204/195B,195P |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Howell; Kyle L.
Attorney, Agent or Firm: Welt; Samuel L. Leon; Bernard
S.
Claims
We claim:
1. An electrode arrangement for application to a body surface for
bloodless measurement in connection with the concentration or the
partial pressure of a gas in the blood including, sensor means for
deriving in vivo electrical signals indicative of the partial
pressure of gas in blood and having a face member adapted for body
contact, the improvement comprising:
heating means in direct thermal contact with said sensor means and
adapted to transmit to said face member a thermal condition for
thermal stimulation at the applied body surface of local blood
circulation.
2. An electrode arrangement according to claim 1 whereby said
heating means includes a current source and a resistance winding
connected from said current source.
3. An electrode arrangement according to claim 2 whereby said
heating means also includes:
thermally conductive block means positioned in thermal contact with
said sensor means and said winding being mounted on said block
means.
4. An electrode arrangement according to claim 3 whereby said face
member is of a material adapted for catalysing the electrochemical
reaction at the body surface to which applied.
5. An electrode arrangement according to claim 4 whereby the face
member of said sensor means is of platinum.
6. An electrode arrangement according to claim 3 whereby said
sensor means further includes at said face member a cover membrane,
permeable for the gas to be measured.
7. An electrode arrangement according to claim 1, whereby said
heating means includes: temperature regulating means having a
temperature-measuring element the measuring probe of which is
mounted in the vicinity of said sensor means.
8. An electrode arrangement for application to a body surface for
bloodless measurement in connection with the concentration or the
partial pressure of a gas in the blood comprising:
a substantially cylindrical electrically and heat conductive member
provided with an encircling recess about its outer surface and a
first axial boring on one end-face;
smoothly cylindrical electrode means lying on the member end-face
opposite said boring and electrically and heat-conductively coupled
with said member;
heating winding means mounted in said recess for generating a
thermal condition for application to said body surface;
temperature measuring means mounted in said axial boring;
annular reference electrode means mounted concentrically with the
electrode means;
a contact face of said reference electrode lying in a common plane
with the end-face of the electrode means distal to said member;
an electrolyte film covering the contact face and the end-face of
the electrode means;
membrane means covering said electrolyte film, adapted for body
contact; and
lead means electrically coupled with said electrode means for
deriving in vivo electrical signals indicative of the partial
pressure of gas in blood.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The invention is concerned with an electrode arrangement suitable
for bloodless measurements in connection with the concentration or
the partial pressure of a gas in the blood.
2. Description of the Prior Art
It is known to bloodlessly measure the partial pressure of a gas in
the blood (e.g. of oxygen or CO.sub.2) with electrodes. Generally,
an electrode is applied to a position of the body surface of the
patient, for example the scalp, a wrist, the inner canthus of an
eye, etc. With the presence of an initial potential at the
electrode, an electrochemical reaction takes place at its surface,
whereby gas is diffused through the tissue from the blood (e.g. in
the case of oxygen, its reduction to OH.sup.-ions). The resulting
current is measurable and under certain circumstances is
proportional to the concentration or the partial pressure of the
gas in the blood.
Bare electrodes or electrodes covered with a membrane are suitable,
depending on the particular measurement requirements, and platinum
is preferred for the elctrode material. Typical materials for the
membrane material would include polypropylene, polyethylene,
teflon, mylar, etc.
It has been found that the measured current values derived by the
electrodes are not only a function of the actual partial pressure
of a gas in the blood, but, in addition, depend on the local blood
circulation of the tissue in the electrode measuring region.
Because of the latter, for some measurements, it would be
advantageous to decrease the influence of the blood circulation on
the measuring results by hyperaemising the skin in the measuring
region to increase the blood volume. It has already been proposed
to use suitable vasodilating preparations (for example, histamine,
papaverine, nicotinic acid, etc.) for this purpose. However, the
application of such preparations is problematical in certain cases,
for example, in the case of measurement on the inner canthus of the
eye.
SUMMARY OF THE INVENTION
Accordingly, it is the purpose of the present invention to provide
an electrode arrangement in which the local blood circulation and
thus the blood volume in the measuring region of the electrode is
increased to enhance the transport of gas from the blood and also
the system response time,without additional application of
hyperaemising preparations. This is achieved by providing an
electrode arrangement with a heater for the thermal stimulation of
local blood circulation.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 shows a longitudinal section through one embodiment of an
electrode arrangement according to the invention, with a bare
electrode for detecting a substance (for example, a gas) dissolved
in the blood.
FIG. 2 shows a section through another embodiment of an electrode
arrangement according to the invention, for partial pressure
measurements.
FIG. 3 shows a schematic electrical circuit of the heating winding
connection to a current source.
DESCRIPTION OF THE PREFERRED EMBODEMENT
The electrode arrangement shown in FIG. 1 is particularly suitable
for detecting at the inner canthus of an eye, a gas (for example,
hydrogen) transported by the circulation. With it one may measure,
for example, the transport time of an inhaled gas in the blood
pathway from the lung to the inner canthus.
A platinum electrode 11 serves as the contact medium with the skin
of the inner canthus of an eye. Its configuration is generally
cylindrical with a approximately 3 mm diameter and a spherically
rounded-off contact or application surface at the tip which proves
to be quite advantageous for this purpose. The platinum electrode
11 is inserted firmly in a copper socket 12 to provide a good heat
conduction connection. The copper socket 12 likewise has a
substantially cylindrical shape of about double the diameter of
platinum electrode 11 with an axial boring to receive the platinum
electrode. On the face opposite the axial boring for receiving the
platinum electrodes is a second axial boring a smaller diameter
which leads to the vicinity of the platinum electrode 11. This
second axial boring serves to receive a temperature measuring
element 14, for example a thermistor, and its lead 17.
The outer surface of the copper socket 12 is interrupted by an
encircling, broad recess about which is wound a heating winding 13,
for example, a resistance wire. The lead 18 to the heating winding
is passed from end-face of the copper socket 12 through an
eccentric boring to a suitable current source 10 as is illustrated
in FIG. 3. A lead 16 for the electrode current is attached in a
further eccentric boring. The whole arrangement is enclosed by a
substantially cylindrical capsule 15 of a plastic (e.g. of PVC,
nylon) which only leaves free the tip of the platinum electrode 11
and, on the opposite face, the lead wires 16, 17, 18, which are
expediently incorporated into a single cable.
Another embodiment is illustrated in FIG. 2, which is especially
suitable for quantitative partial pressure measurements of O.sub.2,
H.sub.2 etc. on the skin. Here a disc-shaped platinum electrode 21
is in heat-conducting contact with a substantially cylindrical
copper block 22 of the same diameter as platinum electrode 21. The
outer surface of the copper block 22 is provided with an encircling
recess in which is located at heating winding 23. The lead 28 to
the heating winding passs through a boring which connects the
end-face of the copper block 22 opposite the platinum electrode 21
with the encircling recess. A further eccentrically disposed boring
in this end-face serves for the attachment of the lead 26 for the
electrode current. In addition, directed from the same face of the
copper block into the vicinity of the platinum electrode 21 is an
axial boring in which is located a temperature-measuring element 24
with the leads 27.
A silver ring 29, serving as a reference electrode, is chlorinated
on one of its flat faces and displays an internal diameter which is
greater than the diameter of the platinum electrode. It is so
arranged that its entire chlorinated face lies in a common plane
with the outer exposed face of the platinum electrode 21. A lead 31
is directed to the back face of the silver ring and is combined
with the leads 26, 27, 28 into a single cable. The whole
arrangement is enclosed with a smoothly cylindrical capsule 25 of a
suitable plastic (for example, PVC, nylon, etc.). As depicted, one
end-face of the capsule 25 lies in the plane defined by platinum
electrode 22 and silver ring 29, leaving exposed their surfaces.
The whole end-face, including the platinum and AgCl surface, is
coated with an electrolyte film 32 and thereover covered with a
suitable membrane 33 (e.g. teflon). This member 33, serving as the
application or skin contact surface of the electrode arrangement,
is secured by a substantially annular capsule 34. In order to
exclude the access of gas from outside, the gap between the two
capsules 25 and 34 is sealed off by an O-ring 35 which is fitted in
corresponding ring grooves.
It has been found that heating up of the skin, in the region of the
measuring electrode, to about 40.degree.-42.degree. C is
reasonable. A markedly higher temperature is, as a rule, not
admissible because of the skin lesions caused by it. In operation,
the heating spiral is provided with a current the strength of which
is regulated with the aid of the temperature-measuring element. Any
known temperature-regulation circuit 20 is suitable for this
purpose, as long as it is sufficiently sensitive.
The electrode in accordance with the invention is particularly
advantageous since it makes possible a hyperaemization in the
region of the tissue and the skin in which the measurement is
undertaken without additional preparations having to be applied.
This is particularly useful when it is desired to measure certain
positions of the body surface where the application of
hyperaemizing preparations is problematical. Such an electrode is
also expedient in the case of mass investigations.
An additional advantage of the electrode is the considerable
stabilization of the electrode reaction, to provide a measurement
in a standarized environment as the influence of fluctuations of
the ambient temperature, i.e. both of the surrounding air and of
the skin, is eliminated.
* * * * *