EP1390734A1 - Systeme d'electrodes pour capteur electrochimique - Google Patents
Systeme d'electrodes pour capteur electrochimiqueInfo
- Publication number
- EP1390734A1 EP1390734A1 EP02771618A EP02771618A EP1390734A1 EP 1390734 A1 EP1390734 A1 EP 1390734A1 EP 02771618 A EP02771618 A EP 02771618A EP 02771618 A EP02771618 A EP 02771618A EP 1390734 A1 EP1390734 A1 EP 1390734A1
- Authority
- EP
- European Patent Office
- Prior art keywords
- substrate
- electrode
- micro
- deposited
- conductive layer
- 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.)
- Withdrawn
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
- G01N27/4166—Systems measuring a particular property of an electrolyte
- G01N27/4168—Oxidation-reduction potential, e.g. for chlorination of water
-
- 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
- G01N27/403—Cells and electrode assemblies
Definitions
- the present invention relates to electrochemical sensors intended to measure the concentration of a chemical substance in a liquid. Such devices find a particularly interesting, but not exclusive, application for the detection of chlorine levels in drinking water or swimming pool water.
- Electrochemical sensors of this type necessarily include a measurement electrode, a reference electrode and a counter electrode.
- Another type of such sensor is also known, which further comprises a so-called generator electrode and its counter electrode.
- the addition of these last two electrodes, the effect of which is to create changes in the concentration of species present in solution, makes it possible to locally control the environment of the measurement electrode.
- the pH of the solution can be changed locally by applying a current to the generator electrode.
- a cathodic current will cause the production of OH- ions (the pH then becoming more basic) and, conversely, an anodic current will cause the production of H + ions (the pH then becoming more acidic).
- a counter electrode associated with the generator electrode, a counter electrode associated with the measurement (or working) electrode and a reference electrode are necessary for the production of a complete sensor. These latter electrodes, the dimensions of which need not be microscopic, are well known in the field under consideration and can be mounted separately.
- the document US Pat. No. 5,597,463 describes, for example, a sensor of this second type, intended for carrying out a titration and with which the measurement carried out is of potentiostatic type.
- Document GB 2 290 617 proposes a structure with micro-electrodes in which the measurement electrode and the generator electrode are in the form of two combs the fingers of which are interdigitated. For at least one of the combs, the fingers have a width which is less than 25 ⁇ m while their length is 20 times, or more, greater than the width. Typically, these fingers have a length of a few millimeters and a width of 20 ⁇ m, the space between two adjacent fingers of the two combs possibly being 20 ⁇ m.
- the object of the present invention is to provide an electrode system in which the measurement electrode and the generator electrode also have micro-structures but which, compared to existing embodiments, the efficiency is improved and the production cost reduced.
- the invention relates to an electrode system for an electrochemical cell, of the type comprising a substrate and, placed on it and close to one another, a measurement electrode. and a generator electrode.
- This system is characterized in that:
- the measurement electrode is formed of a plurality of electrically conductive micro-disks regularly distributed over the substrate and electrically joined together;
- the generator electrode is formed of an electrically conductive plate pierced with circular openings of diameter greater than that of the micro-discs and arranged so that each opening is concentric with a micro-disc.
- the microdisks have a diameter of approximately 5 to 20 ⁇ m and are spaced from one another by approximately 100 to 400 ⁇ m, while the openings have a diameter which is approximately 10 to 100 ⁇ m greater than the diameter micro-discs.
- the substrate is electrically conductive
- an electrically insulating layer is deposited on the substrate and pierced with a plurality of circular openings;
- the micro-discs forming the measurement electrode are constituted by a conductive layer deposited in these openings in contact with the substrate;
- the generator electrode consists of a conductive layer deposited on the insulating layer.
- the substrate is advantageously made of silicon made conductive by doping and an electrically conductive layer is deposited under it.
- the measurement electrode consists of a conductive layer deposited on the substrate
- an electrically insulating layer is deposited on the conductive layer and pierced with a plurality of circular openings delimiting the micro-discs of the measurement electrode; and - the generator electrode consists of a conductive layer deposited on the insulating layer.
- the substrate can be either glass or quartz, or silicon covered with an insulating layer, or silicon made conductive by doping with, then, an electrically conductive layer deposited under it.
- Another object of the present invention is to provide a method for determining the pH of chlorinated water using the sensor having the above characteristics.
- FIG. 1 is a plan view of a micro-electrode system according to the invention.
- FIG. 2 is a partial sectional view on a large scale of a first embodiment of the system of Figure 1;
- - Figure 3 is a diagram showing the effect provided by such an electrode structure;
- FIG. 4 is a partial sectional view on a large scale of a second embodiment of the system of Figure 1; and FIG. 5 shows the variation of the chlorinated species in the water as a function of the value of its pH.
- FIGS. 1 and 2 in which an electrically conductive substrate has been shown at 10 which is in the form of a square plate, typically 2 to 10 mm in side and 0.5 mm thick.
- This plate is advantageously made of silicon made conductive by doping according to techniques well known to those skilled in the art.
- the underside of the substrate 10 is covered with a conductive layer 12 made, for example, of titanium or aluminum or formed of a stack of three sublayers of titanium, platinum and gold.
- the thickness of this layer, deposited according to any known metallization process, is approximately 0.2 to 0.3 ⁇ m.
- the substrate 10 can be a simple metal plate. In this case, the conductive layer 12 is removed.
- the upper face of the substrate 10 is covered with an insulating layer 14 formed, for example, by a stack of two sublayers of Si0 2 and Si 3 N 4 known to have excellent stability in an aqueous medium.
- the thickness of this layer is approximately 0.1 to 0.2 ⁇ m.
- the insulating layer 14 is pierced, for example by etching in a fluorinated plasma, a regular network of circular through openings 16 having, typically, a diameter of about 2 to 20 ⁇ m and spaced from each other by about 100 at 400 ⁇ m. In the example shown in Figure 1, the spacing is 300 ⁇ m.
- This layer 18 is formed, for example, of a stack of a adhesion layer, a diffusion barrier layer and a layer of the desired electrode material.
- This stack for example of titanium, platinum and gold, is deposited all at once, according to any known metallization process, and has a single thickness of approximately 0.2 to 0.3 ⁇ m.
- the layer 18 deposited on the insulating layer 14 is pierced, by chemical etching, by plasma etching or according to the so-called "lift-off" process, with a network of annular openings 24 each surrounding one of the micro-discs 22 and having an outside diameter of about 30 to 120 ⁇ m.
- the annular space thus cleared around the microdisks has a typical width of 5 to 50 ⁇ m. It will be noted that the etching of the layer 18 is done so that the microdisks 22 have a diameter slightly greater than that of the openings 16 and this, in order to avoid any contact of the solution to be measured with the substrate 10.
- microstructure for an electrochemical sensor in which:
- the conductive layer 20 constitutes the generator electrode which can be connected directly to an energy source by a link
- All of the conductive micro-disks 22 constitute the measurement electrode which can be connected to the energy source through the substrate 10 and the layer 12, both conductors, by a link 28 connected to the latter.
- the generator electrode 20 has the effect of creating, in its vicinity, H + or OH " ions according to the applied polarizations.
- FIG. 3 shows, diagrammatically, that this electrode establishes, in the liquid 30 where the structure according to the invention is immersed, a diffusion zone 32 having, typically, a thickness of 50 to 500 ⁇ m depending on the conditions hydrodynamics, and in which the ions created have a concentration gradient.
- the environment of the measurement electrode 22 can thus be modified (increase or decrease in pH) so as to be optimal for the analysis of the detected species.
- These ions then react with the desired substances in the liquid and the resulting changes in the ion concentration are detected thanks to the set of micro-discs 22 forming the measurement electrode.
- micro-disks having two dimensions (length and width) that are small compared to the thickness of the diffusion layer, are micro-electrodes in the strict sense of the term.
- the micro-lines described in the aforementioned document have only one micrometric dimension; they can, therefore, be considered as micro-electrodes only with respect to a single direction of the flow of the solution.
- the structure of the invention has, among others, the following advantages.
- the proposed structure is compatible with batch manufacturing techniques and allows, according to one of its variants, the electrical connection via the rear face of the measurement electrode.
- FIG. 4 represents an alternative embodiment of the structure previously described.
- the conductive substrate 10 of Figure 2 is replaced by an insulating substrate 34, for example, glass or quartz.
- the upper face of the substrate 34 is covered with a conductive layer 36 which, like the layer 18, is made, for example, of titanium or formed of a stack of three sublayers of titanium, platinum and gold. It is deposited according to any known metallization process and has a thickness of approximately 0.2 to 0.3 ⁇ m.
- the upper face of the conductive layer 36 is covered with an insulating layer 38 which, like layer 14, is formed, for example, of a layer of non-stoichiometric silicon nitride (SiNx) which can be deposited using a low temperature process (PECVD).
- the thickness of this layer is typically about 0.1 to 0.2 ⁇ m.
- a photosensitive organic polymer, of the epoxy or polyimide type with a typical thickness of 1 to 2 ⁇ m can also be used in place of silicon nitride.
- the insulating layer 38 is pierced, by chemical etching, with a regular network of circular through openings 40 having, typically, like the openings 16, a diameter of approximately 2 to 20 ⁇ m and spaced apart by approximately 300 ⁇ m.
- the upper face of the insulating layer 38 is covered with a conductive layer 42 of the same composition and the same thickness as the layer 36.
- This layer 42 is pierced, by chemical etching, with a network of circular openings 44 each surrounding l 'one of the openings 40 of the layer 38.
- the annular space thus released around the openings 40 is, typically, from 5 to 50 ⁇ m.
- a microstructure for an electrochemical sensor is produced, in which: the conductive layer 42 constitutes the generator electrode which can be connected directly to an energy source by a link not shown, and
- the conductive layer 36 constitutes the measurement electrode, active only by its portions 46 uncovered by the openings 40, which can be connected directly to the energy source by a link not shown.
- the variant embodiment of FIG. 4 can itself give rise to a first variant in which the substrate 34 is formed from a non-specially doped silicon wafer covered with an insulating layer and to a second variant in which the substrate is formed, as in Figure 2, a highly doped silicon wafer whose rear face is covered with a conductive layer for connection.
- FIG. 5 Reference will now be made to FIG. 5 to describe an advantageous application of a sensor provided with a generator electrode according to the present invention.
- chlorine is widely used for the disinfection of swimming pool water or drinking water distribution circuits.
- the chlorine added to the water is in the form of hypochlorous acid (HOCI) or in the form of hypochlorite (OCI " ), their respective concentrations depending on the pH value, as indicated by the curves of Figure 5.
- the generator electrode being inactive, the A concentration of hypochlorous acid is first measured. Then, the generator electrode is activated so as to modify, locally at the level of the microdisks, the solution by making it more acidic (pH ⁇ 5.5) and the concentration B of hypochlorous acid is measured. The pH of the solution is then determined by the value of the A / B ratio. In order to make this determination as accurate as possible, however, the following precautions should be taken.
- the material of the electrode measurement should be very sensitive to hypochlorous acid and very little sensitive to hypochlorite. A material such as carbon can, in this regard, be considered satisfactory.
- an anionic membrane for example of a material sold under the name of Nafion, which does not allow anions to pass (such as OCI anions " ) makes it possible to guarantee that only hypochlorous acid will be taken into account.
- OCI anions such as OCI anions "
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)
- Investigating Or Analyzing Materials By The Use Of Electric Means (AREA)
Abstract
Description
Claims
Applications Claiming Priority (3)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
CH950012001 | 2001-05-22 | ||
CH00950/01A CH697478B1 (fr) | 2001-05-22 | 2001-05-22 | Système d'électrodes pour capteur électrochimique et procédé de détermination du PH d'une eau chlorée. |
PCT/CH2002/000269 WO2002095387A1 (fr) | 2001-05-22 | 2002-05-16 | Systeme d'electrodes pour capteur electrochimique |
Publications (1)
Publication Number | Publication Date |
---|---|
EP1390734A1 true EP1390734A1 (fr) | 2004-02-25 |
Family
ID=4550016
Family Applications (2)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP01810525A Withdrawn EP1260813A1 (fr) | 2001-05-22 | 2001-05-31 | Système d'électrodes pour capteur électrochimique |
EP02771618A Withdrawn EP1390734A1 (fr) | 2001-05-22 | 2002-05-16 | Systeme d'electrodes pour capteur electrochimique |
Family Applications Before (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
EP01810525A Withdrawn EP1260813A1 (fr) | 2001-05-22 | 2001-05-31 | Système d'électrodes pour capteur électrochimique |
Country Status (5)
Country | Link |
---|---|
US (1) | US7270736B2 (fr) |
EP (2) | EP1260813A1 (fr) |
JP (1) | JP4125136B2 (fr) |
CH (1) | CH697478B1 (fr) |
WO (1) | WO2002095387A1 (fr) |
Families Citing this family (11)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US7201831B2 (en) * | 2002-02-22 | 2007-04-10 | Water Security And Technology, Inc. | Impurity detection device |
US20050164371A1 (en) * | 2003-03-28 | 2005-07-28 | Fujitsu Limited | Cavity electrode structure, and sensor and protein detection device using the same |
EP1557665A1 (fr) | 2004-01-21 | 2005-07-27 | CSEM Centre Suisse d'Electronique et de Microtechnique SA | Système d'electrodes pour capteur electrochimique |
EP1715334A1 (fr) | 2005-04-22 | 2006-10-25 | Adamant Technologies SA | Procédé utilisant un capteur électrochimique et électrodes formant ce capteur |
US20060272898A1 (en) * | 2005-06-03 | 2006-12-07 | Telemark Holdings, Llc | Climbing apparatus |
KR101184612B1 (ko) * | 2006-08-18 | 2012-09-21 | 삼성전자주식회사 | 관통전극 형성방법을 이용한 멤스 구조물 및 그 제조방법 |
FR2930900B1 (fr) * | 2008-05-06 | 2010-09-10 | Commissariat Energie Atomique | Dispositif de separation de biomolecules d'un fluide |
WO2012170774A1 (fr) | 2011-06-10 | 2012-12-13 | Lumetta Michael | Système et procédé pour générer un composé contenant du chlore |
FR2978550B1 (fr) * | 2011-07-25 | 2014-07-11 | Veolia Water Solutions & Tech | Dispositif pour la mesure de la teneur en chlore libre d'une eau |
JP6814990B2 (ja) * | 2016-01-28 | 2021-01-20 | 学校法人慶應義塾 | 残留塩素測定方法及び残留塩素測定装置 |
CN110753840A (zh) * | 2017-06-16 | 2020-02-04 | 学校法人庆应义塾 | 残留氯测定方法及残留氯测定装置 |
Family Cites Families (13)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US4062750A (en) * | 1974-12-18 | 1977-12-13 | James Francis Butler | Thin film electrochemical electrode and cell |
US4176031A (en) * | 1978-03-17 | 1979-11-27 | Fischer & Porter Co. | Digital hypochlorous acid analyzer |
AT403528B (de) * | 1989-04-04 | 1998-03-25 | Urban Gerald | Mikro-mehrelektrodenstruktur für elektrochemische anwendungen und verfahren zu ihrer herstellung |
GB8927377D0 (en) * | 1989-12-04 | 1990-01-31 | Univ Edinburgh | Improvements in and relating to amperometric assays |
FR2675260B1 (fr) * | 1991-04-12 | 1994-10-21 | Aix Marseille Univers Droit Ec | Procede et appareil pour le dosage electrochimique d'un corps dans une solution. |
DE4131731A1 (de) * | 1991-09-24 | 1993-05-19 | Raymond Glocker Gmbh Inst Fuer | Sensor zur bestimmung von chemischen verbindungen in fluessigkeiten und gasen |
US6051380A (en) * | 1993-11-01 | 2000-04-18 | Nanogen, Inc. | Methods and procedures for molecular biological analysis and diagnostics |
GB9412789D0 (en) * | 1994-06-24 | 1994-08-17 | Environmental Sensors Ltd | Improvements to electrodes |
GB9412820D0 (en) | 1994-06-25 | 1994-08-17 | Siemens Plessey Controls Ltd | Water quality measuring apparatus |
GB9413525D0 (en) | 1994-07-05 | 1994-08-24 | Unilever Plc | Improvements in or relating to electrochemical instruments |
GB9502740D0 (en) * | 1995-02-13 | 1995-03-29 | Squared Technology Limited M | Aqueous liquid analysis |
CA2173932A1 (fr) * | 1996-04-11 | 1997-10-12 | Gilles Y. Champagne | Procede de fabrication de matrices de microelectrodes |
GB9609301D0 (en) * | 1996-05-03 | 1996-07-10 | Wallace & Tiernan Ltd | Measuring chlorine concentration |
-
2001
- 2001-05-22 CH CH00950/01A patent/CH697478B1/fr not_active IP Right Cessation
- 2001-05-31 EP EP01810525A patent/EP1260813A1/fr not_active Withdrawn
-
2002
- 2002-05-16 US US10/478,749 patent/US7270736B2/en not_active Expired - Fee Related
- 2002-05-16 JP JP2002591811A patent/JP4125136B2/ja not_active Expired - Fee Related
- 2002-05-16 EP EP02771618A patent/EP1390734A1/fr not_active Withdrawn
- 2002-05-16 WO PCT/CH2002/000269 patent/WO2002095387A1/fr active Application Filing
Non-Patent Citations (1)
Title |
---|
See references of WO02095387A1 * |
Also Published As
Publication number | Publication date |
---|---|
US20040154934A1 (en) | 2004-08-12 |
JP2004525389A (ja) | 2004-08-19 |
JP4125136B2 (ja) | 2008-07-30 |
CH697478B1 (fr) | 2008-11-14 |
US7270736B2 (en) | 2007-09-18 |
EP1260813A1 (fr) | 2002-11-27 |
WO2002095387A1 (fr) | 2002-11-28 |
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