GB2079474A - Electrocatalytic activation of electrodes - Google Patents
Electrocatalytic activation of electrodes Download PDFInfo
- Publication number
- GB2079474A GB2079474A GB8120829A GB8120829A GB2079474A GB 2079474 A GB2079474 A GB 2079474A GB 8120829 A GB8120829 A GB 8120829A GB 8120829 A GB8120829 A GB 8120829A GB 2079474 A GB2079474 A GB 2079474A
- Authority
- GB
- United Kingdom
- Prior art keywords
- electrode
- current
- working electrode
- activating
- compensating
- 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.)
- Granted
Links
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N27/00—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means
- G01N27/26—Investigating or analysing materials by the use of electric, electrochemical, or magnetic means by investigating electrochemical variables; by using electrolysis or electrophoresis
- G01N27/416—Systems
- G01N27/48—Systems using polarography, i.e. measuring changes in current under a slowly-varying voltage
Landscapes
- Chemical & Material Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Health & Medical Sciences (AREA)
- Physics & Mathematics (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Electrochemistry (AREA)
- Molecular Biology (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Electrolytic Production Of Non-Metals, Compounds, Apparatuses Therefor (AREA)
Abstract
In an electrochemical cell, such as a polarographic cell, an electrode at which an electrochemical reaction is to take place during operation of the cell is electrocatalytically activated by supplying to it a controlled activating current. The polarographic cell may operate in an amperostatic mode, (Figure 4) with an activating current of sine wave form applied simultaneously with the measurement of concentration of an active species, or the cell may operate in a potentiostatic mode (Figure 5) with the activating current applied alternately with the use of the cell to measure an active species. <IMAGE>
Description
SPECIFICATION
Electrocatalytic activation
In this specification the term "active species" means a species which is oxidisable or reducible under the conditions prevailing in an electrochemical cell, and the term "active site" means a location at which such a reaction can take place.
In electrochemistry it is sometimes found that, for a particular reaction to be possible, an electrode must be used which has a catalytic effect on the reaction. Often such electrodes need to be activated in some way before use and at frequent intervals in order to retain their activity. In an electrochemical measuring cell, the electrode may need to be activated before each meausrement. Other applications lie in preparative electrochemistry and in fuel cells.
Although electrocatalysis is not completely understood at present, it is believed that for an electrode to be active it must have on its surface many active sites of different types so that a molecule can be adsorbed onto the electrode surface and in some cases can react with another molecule on the surface; reaction products must then desorb to free the adsorption site for further unreacted molecules.
It has been the practice to activate a catalytic electrode by the application of a variety of procedures, largely arbitrary. The particular procedure varies according, more or less, to the personal preference of a worker in the field, but an activating voltage may be applied to swing the electrode first to an anodic value then a cathodic value, and so on. A large current may flow during this 'activation' procedure, and any electrochemical device incorporating the electrode may take a long time to "settle down" i.e. for the background current through a measuring device to return to a level which is low with respect to the value of current dependent on the concentration of the reducible or oxidisable substance to be measured, or for the rate of change of the background current to return to an acceptably low level.
Further, it may be that the application of relatively high voltages results in deactivation rather than activation.
According to the invention an electrochemical cell comprises a first electrode; a second electrode; a container for an electroyte which, when present, contacts both electrodes; means for maintaining the first electrode at a potential such that an electrochemical reaction takes place at the first electrode when an active species as hereinbefore defined is present; and means for supplying a controlled electrical activating current to the first electrode whereby the cell can be electro-catalytically activated. The activating current may be continuous or intermittent and may flow in one direction only or alternately in both directions.
The electrochemical cell may be a polarographic cell for measuring the concentration of an active species in a fluid. The electrolyte may contact the electrodes either directly or through a "salt bridge", i.e. a viscous liquid or a solid electrolyte. If the potential of the first electrode is to be measured or controlled accurately, a reference electrode must also be provided so that potential can be measured with respect to a reference electrode. Further, a compensating electrode can be provided which is either exposed to a reference fluid or is shielded from exposure to any atmosphere; such an electrode can be used in place of a reference electrode when the operating potential of the first electrode is not critical.
In a first, amperostatic, embodiment the polarographic cell comprises a first, working electrode; a second, auxiliary electrode; a third, compensating electrode; a container for an electrolyte which, when present, contacts the three electrodes; exposure means to expose the working electrode to a fluid under test; amperostatic control means for maintaining a constant d.c. current through the compensating electrode; means for maintaining the working electrode at the same potential as the compensating electrode; measuring means to measure any current through the working electrode due to an active species; and a current source to apply to the working electrode a current of known magnitude whereby the working electrode is activated.
The current source may comprise an oscillator and a resistor in series, when an activating current of sine wave form is applied to the working electrode.
In a preferred form, the compensating electrode is identical to the working electrode, the same current source is connected to the measuring means whereby the activating current is backed off, and the measurement of the concentration of the active species is made simultaneously with the application of the activating current.
In a second, potentiostatic, embodiment the polarographic cells comprises a first, working electrode; a second, auxiliary, electrode; a third, reference electrode; a container for an electrolyte which, when present, contacts the three electrodes; exposure means to expose the working electrode to a fluid under test; potentiostatic control means for automatically adjusting the current through the working electrode whereby that electrode is held at a required potential with respect to the reference electrode; a current source to apply to the working electrode an activating current of known magnitude; and switch means arranged to switch the cell between a first, activating, mode in which said activating current is supplied and the working electrode is allowed to differ in potential from said required potential, and a second, measuring, mode in which the working electrode is held at said required potential and the current through the working electrode is measured. In a preferred form, the current source comprises means to supply a direct current of known magnitude and direction.
The invention also extends to a method of activating an electrode in an electrochemical cell by supplying to the electrode an activating current of controlled magnitude, and to amperostatic and potentiostatic methods of measuring an active species in a fluid utilising such an activation method.
In the accompanying drawings, Figure 1 is an exploded view of an electrochemical measuring cell for measuring the concentration of a gas in a fluid, and Figures2 and 3 illustrate respectively a known amperostatic and a known potentiostatic circuit for use with such a cell.
The invention will be described by way of example with reference to Figures 4 and 5 which show modifications to the Figures 2 and 3 circuits for allowing catalytic activation and in which:
Figure 4 is an amperostatic system applying sine wave activation; and
Figure 5 is a potentiostatic system applying square wave activation.
In Figure 1 a polarographic cell comprises a cell body 10 having a hollow centre 12 which can contain an electrolyte. The outer wall of the cell has two circular recesses 14, 16 connected to the centre 12 through narrow channels 15; a dialysis membrane 18, 20 can lie in each circular recess. Two metallised membrane electrodes 22, 24 each comprise a nonporous but gas-permeable membrane of polymeric material onto which a thin layer of electrode metal has been evaporated or sputtered; in use the metallised sides are arranged in contact with the respective dialysis membranes and the electrodes are held in place by a sealing gasket 26 held in turn by a clamping plate 28 which is screwed to the cell body.An area of the gasket 26 is of porous material and an area of the clamping plate 28 is formed of a sintered material, these areas being aligned with the membrane electrode 22 and forming a porous gas diffusion feed to the electrode from outside the cell.
Two contact spots 21, 23 contact the metallised faces of the membrane electrodes 22,24 and allow connection to an electrical control circuit (not shown in Figure 1). The cell also contains an auxiliary electrode 30 in the form of a wire arranged in geometrical symmetry with respect to the two membrane electrodes and further contains a reference electrode 25 and a thermistor 32, which can both be connected to the electrical circuit.
In use, the cell is filled with a suitable electrolyte which contacts the auxiliary electrode and reference electrodes directly, and contacts the membrane electrodes through the channels 15 and dialysis membranes 18, 20. An atmosphere under test diffuses through the feed area to the membrane electrode 22, which is the working electrode. The atmosphere diffuses through the permeable membrane to the electrolyte in contact with the metallised face at which any active species is electrochemically oxidised or reduced, the conditions such as the potential at which the working electrode is held, and the electrolyte, being chosen to suit a gas which is to be detected or measured.No gas reaches the other membrane electrode 24, which is the compensating electrode, i.e. the compensenating electrode is identical in structure to the working electrode, but is shielded from the active species. (In a slight variation, not illustrated, the compensating electrode is exposed to a gas atmosphere from which the active species has been removed).
The cell illustrated is provided with both a reference electrode 25 and a compensating electrode 24.
In use only one of these electrodes will be operational giving with the working electrode and the auxiliary electrode a three-electrode cell. In amperostatic use
the compensating electrode will be operational and
in potentiostatic use the reference electrode in
required.
An amperostatic control and measuring circuit is
shown in Figure 2, the cell 10 being represented
schematically and the three electrodes referenced as
in Figure 1. The compensating electrode 24 is
connected to the inverting input of an operational
amplifier 32, the inverting input is also connected
through a resistor 34 to a potentiometer 36 and the
amplifier output is connected to the auxiliary elec
trode 30. The operational amplifier drives through
the compensating electrode 24, via the auxiliary
electrode 30, a current which is defined by the
voltage set on the potentiometer 36 and the series resistor 34; this will be referred to as the compensat
ing current.The compensating and working elec
trodes are both at "virtual common line" potential,
therefore in the absence of an active species the
current carried by the working electrode differs very
little from the current through the compensating
electrode; fluctuations in the background current
through the cell due to varying conditions are
minimised.
The system is not merely a differential system. The
range of potential of the working electrode is acti ly controlled by controlling the background current
through the compensating electrode 24. The range
of potential of the working electrode is such that the
required electrochemical reaction takes place on its
surface over this range of potential; typically a
compensating current of a few nanoamps is set by
applying a few millivolts to a resistor 34 of value
about 1 megohm.
This "amperostatic" system is described in the
specification of U.K. Patent No. 1,385,201. The compensating current is chosen to be suitable for
the gas to be detected and is usually a few
nanoamps. The current through the working elec
trode 22 due to the presence of an active species is
measured via a second operational amplifier 38 to
which the electrode 22 is connected, the amplifier
output supplying a voltmeter 40. The amplifier 38
acts as a current-voltage converter. The gain is set
with the thermistor 32 which has been trimmed to
have a temperature coefficient of resistance identical
to the temperature coefficient of the current output
of the working electrode per unit partial pressure of
the active species. The voltage output per unit partial
pressure of the active species is therefore indepen
dent of temperature.
Figure 3 illustrates an alternative basic current for
use with an electrochemical gas sensing cell, operat
ing on a constant potential or "potentiostatic"
principle. Identical items are referenced as before,
and the compensating electrode is replaced by the
reference electrode 25 which is connected to the
inverting input of an operational amplifier 46 and the
non-inverting input is connected to a potentiometer
48. The amplifier output is connected through an
ammeter 49 to the auxiliary electrode 30, and the
working electrode is earthed.
In this arrangement the amplifier 46 drives
through the auxiliary electrode 30 and the working
electrode 22 whatever current is necessary to keep the working electrode at a potential -V with respect to the reference electrode 25 which is determined by the potentiometer 48 (which supplies +V). The current through the working electrode changes when an active species is oxidised or reduced and the current through this electrode is a measure of the concentration. The auxiliary electrode 30 acts as a current sink, and this current is measured by ammeter 49 to give the measure of concentration.
In the following examples of the technique of electrocatalytic activation according to the invention, modifications of the known amperostatic and potentiostatic circuits are used, but the technique is not limited to such circuit arrangements.
In a first example, illustrated in Figure 4, an amperostatic circuit is modified to apply continuously an activating current in the form of a sine wave. In addition to the circuit components shown in Figure 2, an alternating current voltage generator 52 is connected through a resistor 54 to the compensating electrode 24 and through a variable resistor 58 to the inverting input of the current-to-voltage converting operational amplifier 38.
In this arrangement, in addition to the previously used d.c. compensating current being amplified to the inverting input of the current control amplifier 32, a current having a variation of sine wave form is applied to the compensating electrode, the effect of which is continually to swing the voltage of the working electrode so that the oxidation state of the surface of this electrode varies cyclically. This has been found to maintain the activity of the working electrode. It has an advantage that, because the circuit is amperostatic, the current generated at the working electrode, and therefore the concentration of the active species, can be measured simultaneously with the application of the catalytically activating current by use of a difference circuit.A current variation which is identical to the activating current is supplied via the resistor 58 to the measuring device so that the cyclic variations in the measured current are backed off and the effect only of changes in the concentration of active species is detected.
In Figure 5, a potentiostatic circuit similar to that in
Figure 3 is used. Additional components are a switch 60 which allows intermittent disconnection of the non-inverting input of amplifier 46 from the potentiometer 48 which supplies a voltage +V and connection instead to a further potentiometer 62 which supplies a voltage -V. Two further two-pole switches 64, 66 are arranged to provide two condi tions:- (a) the reference electrode 25 is connected to the inverting input of amplifier 46 and the working electrode is earthed, and
(b) the reference electrode is isolated and the inverting input of amplifier 46 is connected to the working electrode which is earthed through resistor 50.
The circuit operates in either a measuring mode (a) or an activating mode (b). With the switches 60, 64 and 66 in the positions shown by the full lines, the circuit measures the current due to conversion of an active species as in Figure 3. With switches 64 and 66 in the positions shown by the dotted lines, an activating current is applied to the working electrode 22; with switch 60 in the full-line position, the current is +V/R; with switch 60 in the dotted-line position, the current is -VR; the result is a square wave current pulse. Such a pulse is more effective in activating an electrode than a sine wave because the effective total voltage swing is greater. The disadvantage of a potentiostatic system is that a measurement cannot be made simultaneously with activation.
An example of an electrochemical cell in which electrocatalytic activation is required is a polarographic cell for measuring the concentration of carbon monoxide gas. CO gas is not easily oxidised.
In an amperostatic electrocatalytic activation circuit, such as that described with reference to Figures 1 and 4, to measure concentrations of CO between 100 and 1000 parts per million in the presence of hydrogen, the effective working electrode area will be a 10 millimetre circular area of gold sputtered onto 12 microns thick polytetrafluoroethylene and an activating current of 0.5 to 2.5 microamps will be required. A sine wave of frequency between 0.05 and 0.25 Hz may be used, with a peak-to-peak amplitude of about 5 nanoamps per square millimetre of electrode projected area. Since a gold electrode loses its catalytic activity quickly, the repeated activation is advantageous.
In a potentiostatic electrocatalytic activation circuit, such as that described with reference to Figures 1 and 5, to measure concentrations of CO between 100 and 1000 parts per million with a 10 millimetre diameter electrode of sputtered platinum, a d.c.
current of about -50 microamps per square millimetre of electrode projected area of duration 2 seconds followed by a d.c. current of about +50 microamps per square millimetre for the same period may be used; this is equivalent to a 4 second square wave pulse of 100 microamps peak-to-peak.
The activating double pulse may be applied at 1 minute intervals, leaving a 56 second period for measurement. The platinum electrode retains its activity for a longer time than a gold electrode, so the intermittent activation is acceptible. The platinum electrode can also be used to measure the concentration of hydrogen.
It is believed that this is the first time that current control has been applied to electrocatalytic activation. The technique may be used in conjunction with a measuring cell, as in the two examples described, or in a fuel cell or any other electrochemical cell in which oxidation or reduction at an electrode is required: the electrode need not be a metallised membrane but can have other forms. The activating current can be controlled precisely, consequently the background current through the cell quickly returns either to an acceptably low level in comparison with the response of the cell, or to an acceptably low rate of change.
Claims (10)
1. An electrochemical cell comprises a first electrode; a second electrode; a container for an electro lyte which, when present, contacts both electrodes; means for maintaining the first electrode at a potential such that an electrochemical reaction takes place at the first electrode when an active species as hereinbefore defined is present; and means for supplying a controlled electrical activating current whereby the first electrode can be electrocatalytically activated.
2. An electrochemical cell according to Claim 1 which is a polarographic cell comprising a first, working electrode; a second, auxiliary electrode; a third, compensating electrode; a container for an electrolyte which, when present, contacts the three electrodes; exposure means to expose the working electrode to a fluid under test; amperostatic control means for maintaning a constant d.c. current through the compensating electrode; means for maintaining the working electrode at the same potential as the compensating electrode; measuring means to measure any current through the working electrode due to an active species; and a current source to apply to the compensating electrode a current of known magnitude whereby the working electrode is activated.
3. An electrochemical cell according to Claim 2 in which the current source comprises an oscillator and a resistor in series, whereby an activating current of sine wave form is applied to the compensating electrode.
4. An electrochemical cell according to Claim 2 or Claim 3 in which the compensating electrode is identical to the working electrode and in which said current source is connected to the measuring means whereby the activating current is backed off and the measurement of the concentration of the active species is made simultaneously with the application of the activating current.
5. An electrochemical cell according to Claim 1 which is a polarographic cell comprising a first, working electrode; a second, auxiliary, electrode; a third, reference electrode; a container for an electrolyte which, when present, contacts the three electrodes; exposure means to expose the working electrode to a fluid under test; potentiostatic control means for automatically adjusting the current through the working electrode whereby that electrode is held at a required potential with respect to the reference electrode; a current source to apply to the working electrode an activating current of known magnitude; and switch means arranged to switch the cell between a first, activating, mode in which said activating current is supplied and the working electrode is allowed to differ in potential from said required potential, and a second, measuring, mode in which the working electrode is held at said required potential and the current through the working electrode is measured.
6. An electrochemical cell according to Claim 5 in which said current source comprises means to supply a direct current of known magnitude and direction.
7. A method of activating an electrode in an electrochemical cell comprising supplying to the electrode an activating current of controlled magnitude.
8. An amperostatic method of measuring in a fluid an active species as hereinbefore defined comprising exposing a working electrode to the fluid and to an electrolyte; exposing an auxiliarywelec- trode and a compensating electrode to the electrolyte and maintaining through the auxiliary and compensating electrodes a d.c. current; applying to the compensating electrode a current of sine wave form so that the working electrode is electrocatalytically activated; and simultaneously measuring any current through the working electrode due to the active species.
9. A potentiostatic method of measuring in a fluid an active species as hereinbefore defined comprising exposing a working electrode to the fluid and to an electrolyte; exposing an auxiliary electrode and a reference electrode to the electrolyte; and alternately automatically adjusting the current through the working electrode whereby that electrode is held at a required potential with respect to the reference electrode and measuring the current through the working electrode due to the active species, and applying to the working electrode an activating current of controlled magnitude and allowing the potential of the working electrode to differ from the required potential.
10. An electrochemical cell as hereinbefore de scribedwith reference either to Figures 1 and 4 or to
Figures 1 and 5 of the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8120829A GB2079474B (en) | 1980-07-10 | 1981-07-06 | Electrocatalytic activation of electrodes |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8022642 | 1980-07-10 | ||
| GB8120829A GB2079474B (en) | 1980-07-10 | 1981-07-06 | Electrocatalytic activation of electrodes |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2079474A true GB2079474A (en) | 1982-01-20 |
| GB2079474B GB2079474B (en) | 1984-05-10 |
Family
ID=26276176
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8120829A Expired GB2079474B (en) | 1980-07-10 | 1981-07-06 | Electrocatalytic activation of electrodes |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2079474B (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0107756A2 (en) * | 1982-10-28 | 1984-05-09 | International Business Machines Corporation | Electronic circuit for analyzing the operation of electrochemical cells |
| US4496454A (en) * | 1983-10-19 | 1985-01-29 | Hewlett-Packard Company | Self cleaning electrochemical detector and cell for flowing stream analysis |
| US4566949A (en) * | 1983-10-19 | 1986-01-28 | Hewlett-Packard Company | Method of operating a self cleaning electrochemical detector |
| US4705617A (en) * | 1983-05-06 | 1987-11-10 | Sensormedics Corporation | Apparatus for deplating cutaneous gas sensors |
| EP0395222A2 (en) * | 1989-04-27 | 1990-10-31 | AMERSHAM INTERNATIONAL plc | Improvements relating to biosensors |
| FR2675260A1 (en) * | 1991-04-12 | 1992-10-16 | Aix Marseille Univers Droit Ec | Process and apparatus for the electrochemical determination of a substance in a solution |
| EP0791821A1 (en) * | 1995-09-12 | 1997-08-27 | Eisai Co., Ltd. | Method and apparatus for detecting electrochemiluminescence |
| WO2002073182A3 (en) * | 2001-03-09 | 2003-05-30 | Bosch Gmbh Robert | Method for the operation of an analytical circuit for an electrochemical cell |
| EP0710835A3 (en) * | 1994-11-02 | 2003-07-30 | Toyota Jidosha Kabushiki Kaisha | Apparatus for detecting carbon monoxide, organic compound, and lower alcohol, and methods of the same |
-
1981
- 1981-07-06 GB GB8120829A patent/GB2079474B/en not_active Expired
Cited By (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0107756A2 (en) * | 1982-10-28 | 1984-05-09 | International Business Machines Corporation | Electronic circuit for analyzing the operation of electrochemical cells |
| EP0107756A3 (en) * | 1982-10-28 | 1985-04-24 | International Business Machines Corporation | Electronic circuit for analyzing the operation of electrochemical cells |
| US4705617A (en) * | 1983-05-06 | 1987-11-10 | Sensormedics Corporation | Apparatus for deplating cutaneous gas sensors |
| EP0140286A3 (en) * | 1983-10-19 | 1988-07-20 | Hewlett-Packard Company | Electrochemical detector |
| US4566949A (en) * | 1983-10-19 | 1986-01-28 | Hewlett-Packard Company | Method of operating a self cleaning electrochemical detector |
| EP0140286A2 (en) * | 1983-10-19 | 1985-05-08 | Hewlett-Packard Company | Electrochemical detector |
| US4496454A (en) * | 1983-10-19 | 1985-01-29 | Hewlett-Packard Company | Self cleaning electrochemical detector and cell for flowing stream analysis |
| EP0395222A2 (en) * | 1989-04-27 | 1990-10-31 | AMERSHAM INTERNATIONAL plc | Improvements relating to biosensors |
| EP0395222A3 (en) * | 1989-04-27 | 1993-04-07 | AMERSHAM INTERNATIONAL plc | Improvements relating to biosensors |
| FR2675260A1 (en) * | 1991-04-12 | 1992-10-16 | Aix Marseille Univers Droit Ec | Process and apparatus for the electrochemical determination of a substance in a solution |
| EP0710835A3 (en) * | 1994-11-02 | 2003-07-30 | Toyota Jidosha Kabushiki Kaisha | Apparatus for detecting carbon monoxide, organic compound, and lower alcohol, and methods of the same |
| EP0791821A1 (en) * | 1995-09-12 | 1997-08-27 | Eisai Co., Ltd. | Method and apparatus for detecting electrochemiluminescence |
| EP0791821A4 (en) * | 1995-09-12 | 1999-10-27 | Eisai Co Ltd | Method and apparatus for detecting electrochemiluminescence |
| WO2002073182A3 (en) * | 2001-03-09 | 2003-05-30 | Bosch Gmbh Robert | Method for the operation of an analytical circuit for an electrochemical cell |
| US7276912B2 (en) | 2001-03-09 | 2007-10-02 | Robert Bosch Gmbh | Method for the operation of an analytical circuit for an electromechanical cell |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2079474B (en) | 1984-05-10 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| US3260656A (en) | Method and apparatus for electrolytically determining a species in a fluid | |
| EP0415388B1 (en) | Method and apparatus for reviving an electrode of a biosensor | |
| FI68323B (en) | GLUKOSGIVARE | |
| EP0141282B1 (en) | Method of and system for real time differential pulse detection | |
| JPH057657B2 (en) | ||
| US3855096A (en) | Electrochemical cells | |
| NL8502371A (en) | ELECTROCHEMICAL CELL FOR QUANTITATIVE DETECTION OF A TOXIC GAS. | |
| GB2079474A (en) | Electrocatalytic activation of electrodes | |
| US20130091936A1 (en) | Electrochemical detection cell for liquid chromatography system | |
| WO1994004912A1 (en) | Chlorine sensor | |
| Cha et al. | Problems associated with the miniaturization of a voltammetric oxygen sensor: chemical crosstalk among electrodes | |
| Hahn et al. | The development of new microelectrode gas sensors: an odyssey. Part 1. O2 and CO2 reduction at unshielded gold microdisc electrodes | |
| Schmidt-Zhang et al. | A novel thick film sensor for simultaneous O2 and NO monitoring in exhaust gases | |
| Gründler et al. | The Technology of Hot‐Wire Electrochemistry | |
| US5368706A (en) | Amperometric detection cell | |
| US4013522A (en) | Method and apparatus for measuring the concentration of carbon monoxide | |
| Alberti et al. | Use of NiO, anodically doped with Ni (III), as reference electrode for gas sensors based on proton conductors | |
| Zhou et al. | Multi-sensor technique and solid-state electrochemical sensor system for real-time and dynamic monitoring of multi-component gases | |
| EP0572824B1 (en) | Galvanic cell type gas concentration sensor system capable of detecting more than one type of gas | |
| Zhou et al. | Non-invasive, real-time and dynamic monitoring of CO2 and O2 simultaneously using modulated potential pulse-amperometry/coulometry | |
| EP0447288B1 (en) | Amperometric detection cell | |
| Zhou et al. | Studies on the biomedical sensor techniques for real-time and dynamic monitoring of respiratory gases, CO2 and O2 | |
| JPS60178346A (en) | Electrode body for measuring concentration of gas and measuring apparatus using the same | |
| JPS5834355A (en) | Twin electrode type voltammetry detection system | |
| KR19990014660A (en) | Dissolved oxygen measuring device using solid electrolyte |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| 732 | Registration of transactions, instruments or events in the register (sect. 32/1977) | ||
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19920706 |