CA1137169A - Device for the transcutaneous electrochemical determination of the partial oxygen pressure in blood - Google Patents

Device for the transcutaneous electrochemical determination of the partial oxygen pressure in blood

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Publication number
CA1137169A
CA1137169A CA000321698A CA321698A CA1137169A CA 1137169 A CA1137169 A CA 1137169A CA 000321698 A CA000321698 A CA 000321698A CA 321698 A CA321698 A CA 321698A CA 1137169 A CA1137169 A CA 1137169A
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Canada
Prior art keywords
measuring
blood
oxygen pressure
heating elements
skin
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired
Application number
CA000321698A
Other languages
French (fr)
Inventor
Hans-Peter Kimmich
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Honeywell BV
Original Assignee
Honeywell BV
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Filing date
Publication date
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Publication of CA1137169A publication Critical patent/CA1137169A/en
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Classifications

    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/145Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/14542Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue for measuring blood gases
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/145Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/1468Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means
    • A61B5/1477Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue using chemical or electrochemical methods, e.g. by polarographic means non-invasive
    • AHUMAN NECESSITIES
    • A61MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61BDIAGNOSIS; SURGERY; IDENTIFICATION
    • A61B5/00Measuring for diagnostic purposes; Identification of persons
    • A61B5/145Measuring characteristics of blood in vivo, e.g. gas concentration, pH value; Measuring characteristics of body fluids or tissues, e.g. interstitial fluid, cerebral tissue
    • A61B5/1491Heated applicators

Abstract

18.12.78 1 PHN.9041 "ABSTRACT":
"Device for the transcutaneous electrochemical deter-mination of the partial oxygen pressure in blood".

A device for the transcutaneous electro-chemical determination of the partial oxygen pressure in blood, comprising a measuring head which includes at least three measuring cells of the Clark-type, comprising periodically actuated heating elements, the actuation of the heating elements being realized at a phase difference such that always at least one measuring cell provides a reliable measuring value.

Description

~1371~;9 "Device for the transcutaneous electrochemical deter-mination of the partial oxygen pressure in blood".
The invention relates to a device for the transcutaneous electro-chemical determination of the partial pressure of oxygen in the blood of humans or animals, comprising a measuring head which includes a measuring cell which is provided with electrodes and which comprises a surface which is to be arranged in contact with the skin and which can be heated by an electrical heating element.
A device of this kind is known from Netherlands Patent Specifica-tion 152,084, F. Hoffmann-Laroche ~ Co. A.G. published January 17, 1977.
The measuring cell comprises a measuring electrode which is made of, for example, platinum and a reference electrode which is made of, for example, silver/silver chloride. These electrodes are arranged in an electrolyte, for example, a KCl solution which is separated from the surroundings by an oxygen-permeable diaphragm. A measuring cell of this kind is known as a Clark cell. In the known device, the Clark cell furthermore comprises a heating element whereby the surface thereof which is to be arranged in con-tact with the skin can be heated. This heating element on the one hand serves to widen the peripheral blood vessels, so that the supply of blood is increased and the peripheral venous system is actually filled with arterial blood at this area, whilst on the other hand ., ~k ~- r~
. ~J~.

.,~, -~. ~ .
'' - . " ' ' , .

1~37169 ~ .7S 2 Pl-IN.901s1 it serves to accelerate the oxygen diffusion through tl~e sk:in. E~perill1ents have demonstrated tha-t a better correla-tiorl betweell the arterial parlial oxygen pressure and the transcutaneously meQsured oxygen pressure is thus obtained. A more thorough consideration of the various factors on which the transcutaneously measured oxygen pressure depends, however, shows that this correlation is good only if these factors cancel each other more or less by chance.
In arterial blood an equilibrium exists between the percentage of oxidized haemo~globine anc the partial oxygen pressure. When the blood is heated, this equi-librium is shifted so that the partial oxygen pressure increases. Therefore, when the described measurin~ method is used, the partial oxygen pressure in the peripheral blood vessels is higher thar. in the arteries. During the diffusion through the skin, tha skin cells consume oxygen, so that the oxygen pressure at the area of the epidermis is lower than in the peripheral blood vesse]s. Finally, the Measuring cell also consumes a ~-iven quantity of oxygen. If all these influences just cancel each other, the partial oxygen pressure measured e~uals the arterial - oxygen pressure.
It has been found that this correlation is still poor at a skin temperature o 43 C and often good at 44 C. ~ higher temperature causes pain and burning of the skin. Irritation can also occur at 44 C, if the cluration of the measurement is a few hours or more.
Therefore 9 it is customary to move the measuring head to another area of the skin after every two hours~ which implies additional work for the physician or the nurse and wh cll, mor~ver, increases the rislc of errors.
~ The inventiGn has for its object to provide a : deviceof the described Icind which can be used in one 3 positioll for a very long period of time without objection and whicll, moreover, enables the separate deterlrlination of the effect of at least a number of the factors which :

.

influeltce the correlatiGn bctween the measured oxygen pressure and the actual arterial oxygen yressure.
To this end, the device in accordance with the invention is charac-terized in that the measuring head comprises at least three measuring cells, each cell having its own heating element, the electrodes of each measuring cell forming part of a separate measuring circuit, the heating elements being ` connected to a power supply circuit which is adapted for the periodical actu-ation of the heating elements in a staggaTd fashion for Tl minutes, there being an interval of T2 minutes between two actuations, Tl and T2 being the same for all heating elements and the actuation of a heating element commenc-ing at an instant which lies Tl + T2 minutes after the beginning of the actu-n ation of the preceding heating element, n being the number of heating ele-ments.
A preferred embodiment of the device in accordance with the inven-tion is characterized in that the measuring cells are mounted in a body hav-ing a low heat conductivity, the surface of the measuring cells which can be heated being situated in substantially the same plane as a surface of the body, said surface being surrounded by a non-heated surface of an annular measuring cell which is situated in the same plane and which is to be arranged against the skin, said measuring cell being accommodated in a housing togeth-er with said body.
The invention will be described in detail hereinafter with refer-ence to the accompanying diagrammatic drawings.
Figure 1 is a diagrammatic sectional view of the skin on which a measuring head for measuring the partial oxygen pressure is arranged, Figure 2 diagrammatically illustrated the equilibrium between the : oxidation degree of haemoglobine and the partial oxygen pressure, Figure 3 shows a diagram to illustrate the variation of the partial oxygen pressure between an .

, .

~137169 4 P~ . 9 artery alld n nleasllrillg head, Fi~ is a cross-sectiollal -~iew of an embodime~t of a measuring head for a device in accordance with the in~ention, Fig. 5 is a bottoln view of the measuring head shown in ~ig. 4, Fig. 6 is a block diagram of an e~bodiment of a device in accordance with the invention, ~ig. 7 shows a diagram illustrating the 1n operation of the device shown in Fig. 6, and Fig. 8 shows a measuring curve.
In order to illustrate the problems occurring during the transcutaneous measllrement of the arterial oxygen pressure, ~ig. 1 diagrammatically shows the situation of a measuring head 1 which is arranged on the skin and which is connected to a measuring and power supply circui-t (not shown in Fig. 1), via a cable 3.
~ia an artery 5, oxygen-rich blood of which the partial ; oxygen prcssure is to be measured is applied to a bed of peripheral vessels 7 in which oxygen is given off to the surrounding tissue 9. The blood is subsequently discharged via a vein 11. The ox~gen given off to the tissue 9 diffuses via a layer of livin~ cells 13 to a layer of dead cells 15 and finally reaches the measuring head 1.
Because oxygen is given off to the tissue 9 in the peripheral vessels 7, the partial oxygen pressure in these vessels is generally lower than that in the artery 5. However, it can be ensured that the peripheral - 30 vessels 7 are also filled with artcrial blood by heating the tissue 7, with the result that the peripheral vessels widen to such an exterlt that the drop of the partial oxygen pressure in the klood becomes negligibly small thanks to 1he fast circula~ion. Howe~er5 another effect 35 OCCUI'S which will be explained with reference to Fig.2.
~ n 1he blood ail equilibriu~ e~.is-ts between the partial oxygen pressure P(O2)~ the concentratioIl of oxidized haemoglobine C (HbO) and t-he concentration .
, .

~137169 -7~ ~ P~ .9~

Or ~o~idi~.ed llaelnog]obiJle C (1lb~. The l~ercen.tag( of o~idi~ed hac1no~].obiIl~ is refel-red -to as -the saturation S(o2) S(O2) = --~lIbO) ~ C(Hb) x 100.
The relations1lip between S(O2) and P~O2) is shown in Fig.2 at temperatures of 37 C (uninterrupted curve) and 42 (stroke/dot curve). ~or normal venous blood, the equili.brium is s tuated approxi.mately at the point which is indicated by the reference V,aI~d for normal arterial blood approximate~y at tlle point indicated by t]--e reference A. The Figure clearly shows that, the saturation re~
maining the same 5 ' the partial oxygen pressure increases by an amount ~P1 wherl the blood is heated. As a result, the partial o~ygen press.re in the tissue 9 is higher than if the peripheral vessel~s 7 were fil~ed with arteria]
blood at a temperature of 37 C. ThePath -f`rom the artery 5 ~ to the measuring head 1 :is plot-ted hor.i~oIltally in ~ig.3 : 2~ ~not to scale) and the ox~gen pressure is verti.cally plotted. The arterial oxygen pressure Pa(O2) is increased in the described manner, due to the heating of the blood in the peripheral vessels, by an amo~nt ~Pl. In the dermis - 13 oxygen is consumed by the living cells, thus causing a reduction of the ox~-gen pressure by an amount ~P2.
The oxygen pressure at the area of thc epidermis ' a(2) ~ ~P.I - ~P2. This is the pressure P i(2) which would be measured by means of an ideal ;~ measuring head. An ideal measuring head is a measuring head which does not consume o~ygen itself and ~hich is arranged on the skin in a completely leak--free ma.nner, so that no oxygen can penetrace from the a.ir. It is also assum2d that no lateral leakage through thc skin occurs.
If oxygen en-ters from the air, the pressure Pm (2~ is 35 f`urther increased by an amount ~ Pml and, i~ thc measuring head consumes o~ygen, thi.s pressure is reduced again by an amount ~P c~ sot~lat tlle total oxygen pressure measllred equals.

1137~69 1S. 1 !. ~S 6 PIIN. ~o!l 1 ~ (0") = P,,~,(02) 1 ~pl -~ P2 ~Prn.L ~Pmc ( ) Tl~ se Or ]~llO~ l de~Ti ces rOr tlle 1;
n~eas~lremen1 o. Pa~O2) is based on:
' P 2 ~ ~' P 1 - ~ P n C = ( 2 ) Tllis assumptioll can be verifiec3 by rneasuring P~O2~ in a different ma~ er, for example, by taking a bloc-d sample.
It has been found in practice that the relation (2) is satisfied reasonably well in many cases at a skin temperature of 44 C. Ilowever, certainty never exists in 10 this respect and, moreoverS a temperature of 44 '` leads to skin irritation after some time.
In order to avoid tllese drawbacks, the device - in accordanc e with the invention comprises a measuring 15 head 1 as shown in the Figures 4 and 5. Thi s head com-pri ses a nletal housing 17 in which a body 19 of thermally insulal;ing material is accommodated, said body comprising three ;neasuring ceLls 21. l;he measuring ce]ls ^1 are kno~n Clark cells comprising a heating element s f or 20 example, as described in said Netherlands Patent Speci-fication 152, O~4 or in the article "Transcutalleous measurement of blood PO2" by Renate ~uch e. a. in J . Perinat. Med. 1 ( 1973), pages 183-191 .
The surface 23 of the housing 17 which is to 25 be arranged agai nst the sl~-in is preferably provided with an adllesi~Te layer, so that intimate contact ~ilith tl-~e skin is obtained and only little oxygen leakage occurs.
`~ In order to minimi ze the oxygell entering, for example, throug]l the skin9 an annular measuring cell 25 of the 30 Clark type is accommodated in the housing, the surface thereof ~hich is to be arranged against the housing being !'; situated i~ ' he sarne plane as a surface of the body 19 and the (heated) surface of the measuring cells 21 which is to be arrangcd agai nst the skin. The annular 35 measuring cell 25 is r ot pro~ided with a heating elemellt It col~sllmes substantial part o:t` the oxygen enteri ng by 1 e akat, e .

.' 1~ 1~.7~ 7 Pll~.90~1 . Tl1e n~e~sllr:ing cel].s and heating e]emcnts arc connected, ~:ia connection ~ires (not .shown) ~nd the cable 3, to a measLIri.ng alld powe. sllpI)ly circ-~it, the bloc~ di~ram ol w1~ich is shown in Fig. 6. Each of the measuring cells 21, 25 comprises a-n ~node 27 which is made, for e~ample, of Ag/AgCl, and a cathode 29 which is made of, for example, Pt. These electrodes are situated in a space fi.lled with an electrolyte, for example, a solution of KCl. Tllis space is separated fromthe surroundings by a diaphragm 31 which is permea~le to 2 and which i9 made of, for example, polytetra-fluoroethylene. The electrodes 27, 29 are included, together with a voltage source 33, i.n a circuit in which an electrical current flows which is dependentof the partial oxygen pressure at the area of the diaphragin 31.
In the measuring cells 21 which serve for the actual measurement this current is measured by means of a measuring resistor 35 across which a voltage arises which is proportional to this current and which is applied ; 20 to the inputs of an amplifier 37. The outputs of the three amplifiers 37 are conllected to the inputs of a recording measuring instrument 39.
. As h.as already been stated, each of the three measuring cells 21 is provided with a heating element 41, for example, a resistance winding. These heating elements are connected to a power supply circuit which is formed by a voltage source 43 and three switches 47, 49 and 51 which are con~rolled by a control member 45. When the switch 47 is closed, the first heating element 41 (the upper element in Fig. 6) is active; when the switch 49 is closed, the second heating element is active, and -:.
; when the switch 51 is closedf the third heating element is active. The switches 47, 49 and. 51 may be, for exampl.e~
relays or semicondu.ctor switches. The control member 45 may comprise a mechanical or electronic cloc~ which a]ternately opens and closes the three switches in accord.ance with.the predetermined diagram An example of such a diagram is shown in Fig. 7. Each of -the three .

.7~ ~ P11.~.9~

cur~es in this Figure represents the changing in ihe tin1e of the state of one of the s~itches, the reference nu111eral ~lereby the switc1l is denoted in ~ig.~ being stated bet~een brac1~ets adjacent the relevantcurve at the right. WheIl a curve has t11e level denoted by "O", the rele~ant switch is open and if the curve has the ~evel deno-ted by "1", the switch is closed.
-[t is assumed that the measuring head is arranged on the skin and the recording by means of the measuring instrument 39 commences at the instant t = O.
One of ~he three curves produced by this measuring instrument is shown in ~ig.8. This cur~e represents the measuring result of the firs-t measuring cell 21 (the upper cell in Fig.6) as a function of` the time.
; 15 Fig. ~ shows tha-t the measuring cell in~icates a partial oxygen pressure of 160 mm Hg a-t the instant t = O. This corresponds to the o~gen pressure in the ambient air, ~hich is explained by the fact that a f quantity of air is trapped between the measuring head ~A and the skin when the measuring head is Iit-ted.
.:-As a result of the oxygen consumption of the measuring cells, the oxygen pressure Pm(02) ~radually drops tc a constant value P 3(2) which is lower than the value normally found for venous blood. The latter value amo1lnts to approximately 40 mm lJg, as appears from Fig.2, ancl this approximately the value which could be expected if the skin were not heated. The difference is caused by the oxygen consump-tion in the dermis (~P2) and of the measuring cell (~ P c)' reduced by the oxygen pressure increase due to ingress of air (~P1), in as far as this increase is not cancelled by the allnular mc-asurii~
cell 25. Therefrom9 it follows that the follo-~ing - formula -s a good appro~imation:
P2 t ~Pmc --~P1 = 4 Pm3( 2) As appears from ~ig. 7, all switches 4-7f 49, 51 are closed after 20 mi~ -les. Subsequentlys the S'iiI~
is heated at tne area of the three mcasuring ce'~s 21 1~.1?.7~ 9 PIIN.~0l11 d~1ring 1j mlIlut;es. I)urin~ this poriod, the I)artial oxyge pressure Ineasured illcreases dlIe 1;o 1:he ~idening of the pcrip1leral vesse]s 7, wIIich are t;hus filled with arterial blood, as well as by lhe shi~ting of the saturation curve (see Fig.~)-At the instant t = 35 minutcs, all switches areopened again, after ~hich they are periodically opened and closed, so that eachleating element is each time actuated for T1 minutes, ~-Tith an interval of T2 minuies between t~o successive actuation periods. The actuation of each of the heating elements starts 1 + 2 minutes after the actuation of the preceding heating element, n being tlle number of heating elements. In the described example, ll = 3, T1 = 1 minute and T2 = 9 minutes.
The variation of the partial oxygen pressure measured per measuring cell during each heating and cooling period can be established on the basis of Fig.8.
After theopening of the switcn 47, P (2) gradually - decreases to a substantially constant value P 1(2)~
~n thanks to the fact that the peripheral vessels 7 are - comparatively quickly filled with fresh venous blood of normal ternpera-ture. Because the surrounding tissue 9 main-tains its high temperature for a prolonged period of time, the widening of the peripheral vessels continues to exist.
When the lleating is switched on again (t =
44 minute6) the blood in the periphera] vessels is also heated againS so that the saturation curve is shifted and a higher partial oxygen pressure P 2(02) is measured.
From this it follows that the follow ng is a good approximation:
Pm2(2) - Pm1(2) (Ll) - ~P1 thus forms an indication for the temperature increases at the area of the peripheral blood vessels.

The equation (1) was cLeri~ed for heated blood, so that the vallle for Pm(02) to be inserted therein eq1Ials P 2(2) The following equation is found by combination 1S.1~ 10 PlIN.90~l of tlle equa-t;iol]~ (1), (~) alld (I~) p (G2) ~ Pm1(0~) ~ 40 - PIn3( 2) Fig. S shows that the value Pm1(O2) is avail~ble i`or approximately Il minutes per nleasuring ce]l 21. As a result of the phase sh:~fted periodic actuation of the three heating eleIllellts 41, it is thus ensure(l that always at least one of the three measuringceUs indicates the value P 1(2~' so that tlle partial oxygen pressure of the blood is continuously measured. Because each heating 0 elelllellt i5 actuated for only one minute pcr 10 minutes, no skin irritation occurs Obviously, the number of measuring cells 21 ;; with hea-ting element 41 can be extended, if desired.
~- Alternatively, the heating can be realised in a different manner, for exaMple5 by high frequency heating or by direct heating of the annular catnode 29 w1lich is connected as an electrical resistor. If` dasired, the skin temperature can be measured and the curre-nt through the lleating ele-~ ments can be controlled. Alternatively~ 0Ile circuit shown - in Fig. 6 may also be adap-ted so that a small current flows through thc heating elements also when these elements ; are not actuated, in order to compensate for heat losses of the nleasuring head.

Claims (2)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A device for the transcutaneous electrochemical deter-mination of the partial pressure of oxygen in the blood of humans or animals, comprising a measuring head which includes a measuring cell which is provided with electrodes and which comprises a surface which is to be arranged in contact with the skin and which can be heated by means of an electrical heating element, characterized in that the measuring head comprises at least three measuring cells, each cell having its own heating element, the electrodes of each measuring cell forming part of a separate measuring circuit, the heating elements being con-nected to a power supply circuit which is adapted for the periodical actuation of the heating elements in a staggered fashion for T1 minutes, there being an interval of T2 minutes between two actuations, T1 and T2 being the same for all heating elements and the actuation of a heating element commencing at an instant which lies minutes after the beginning of the actuation of the preceding heating element, n being the number of heating elements.
2. A device as claimed in Claim 1, characterized in that the measuring cells are mounted in a body having a low heat con-ductivity, the surface of the measuring cells which can be heated being situated in substantially the same plane as a surface of the body, said surface being surrounded by a non-heated surface of an annular measuring cell which is situated in the same plane and which is to be arranged against the skin, said measuring cell being accommodated in a housing together with said body.
CA000321698A 1978-02-20 1979-02-15 Device for the transcutaneous electrochemical determination of the partial oxygen pressure in blood Expired CA1137169A (en)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
NL7801869 1978-02-20
NL7801869A NL7801869A (en) 1978-02-20 1978-02-20 DEVICE FOR TRANSCUTANEOUS ELECTROCHEMICAL DETERMINATION OF BLOOD PARTIAL OXYGEN PRESSURE.

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CA1137169A true CA1137169A (en) 1982-12-07

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US (1) US4252123A (en)
JP (1) JPS54123280A (en)
AU (1) AU521361B2 (en)
CA (1) CA1137169A (en)
DE (1) DE2906201C2 (en)
FR (1) FR2417773A1 (en)
GB (1) GB2014739B (en)
IT (1) IT1166640B (en)
NL (1) NL7801869A (en)
SE (1) SE7901377L (en)

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CA1131708A (en) * 1978-09-11 1982-09-14 Wolfgang Mindt Electrode for cutaneous po2 measurement
DE2911601C2 (en) * 1979-03-24 1982-05-13 Hellige Gmbh, 7800 Freiburg Measured value recorder for physiological measured variables with a device for electrical heating
JPS58501659A (en) * 1981-10-13 1983-10-06 ラジオメ−タ・アクチセルスカベット Electrochemical measurement electrode device for blood parameter transcutaneous measurement and blood parameter transcutaneous measurement device
GB2111215A (en) * 1981-10-31 1983-06-29 Alastair Sibbald Electrochemical sensor assembly
US4534356A (en) * 1982-07-30 1985-08-13 Diamond Shamrock Chemicals Company Solid state transcutaneous blood gas sensors
US4781798A (en) * 1985-04-19 1988-11-01 The Regents Of The University Of California Transparent multi-oxygen sensor array and method of using same
WO1986006484A1 (en) * 1985-04-19 1986-11-06 The Regents Of The University Of California Transparent multi-oxygen sensor array
US4890620A (en) * 1985-09-20 1990-01-02 The Regents Of The University Of California Two-dimensional diffusion glucose substrate sensing electrode
EP0248304A3 (en) * 1986-06-06 1989-08-23 Kontron Instruments Holding N.V. Electrodes arrangement
US4821733A (en) * 1987-08-18 1989-04-18 Dermal Systems International Transdermal detection system
DE3736678A1 (en) * 1987-10-29 1989-05-11 Draegerwerk Ag METHOD AND DEVICE FOR OPERATING AND CALIBRATING SEVERAL PROBE FOR BIOLOGICAL OR PHYSIOLOGICAL MEASURED VALUES
US6259937B1 (en) * 1997-09-12 2001-07-10 Alfred E. Mann Foundation Implantable substrate sensor
US6119028A (en) * 1997-10-20 2000-09-12 Alfred E. Mann Foundation Implantable enzyme-based monitoring systems having improved longevity due to improved exterior surfaces
CN106535761B (en) * 2014-07-15 2019-12-17 雷迪奥米特巴塞尔股份公司 interstitial measurement of partial pressure of analytes in skin tissue

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CH530006A (en) * 1970-10-01 1972-10-31 Hoffmann La Roche Electrode arrangement
US3985633A (en) * 1972-11-11 1976-10-12 Eschweiler & Co. Device for the polarographic measurement of oxygen pressure
DE2305049C2 (en) * 1973-02-02 1984-10-25 L. Eschweiler & Co, 2300 Kiel Device for measuring the pH value of blood
DE2530834C2 (en) * 1975-07-10 1985-06-13 Albert Prof. Dr. 3550 Marburg Huch Device for percutaneous measurement of perfusion efficiency

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AU521361B2 (en) 1982-04-01
GB2014739A (en) 1979-08-30
FR2417773A1 (en) 1979-09-14
AU4433079A (en) 1979-08-30
NL7801869A (en) 1979-08-22
DE2906201C2 (en) 1983-01-13
US4252123A (en) 1981-02-24
DE2906201A1 (en) 1979-08-23
GB2014739B (en) 1982-06-30
SE7901377L (en) 1979-08-21
JPS54123280A (en) 1979-09-25
IT1166640B (en) 1987-05-05
IT7920294A0 (en) 1979-02-16

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