Chemistry: electrical and wave energy – Apparatus – Electrolytic
Patent
1997-10-10
1999-11-09
Tung, T.
Chemistry: electrical and wave energy
Apparatus
Electrolytic
427 211, 210348, 204286, 204403, G01N 2726, C25B 1100
Patent
active
059807091
DESCRIPTION:
BRIEF SUMMARY
TECHNICAL FIELD
The present invention relates to a method for defining an area of a coating or layer attached to or in contact with a porous substrate. More particularly, the present invention relates to a method wherein the coating or layer is an electrode. Although the invention will be described with reference to its application in the electrochemical area it is not intended that the invention be limited to that use. It may extend to any application where a defined area of a porous substrate is required.
BACKGROUND ART
In the past it has been found that whenever quantitative electrochemical measurements are performed it is necessary to have both a reproducible and accurately defined electrode area which is in contact with the sample being analysed. When performing a measurement in a bulk solution the usual practice has been either to have the electrode immersed to a certain level in the liquid or alternatively to have an insulation layer applied to the electrode to leave only a precisely defined area in contact with the solution. These practices have proved to be relatively expensive and unreliable. It has also been found that when these methods are used it is difficult to prevent leakage and contact with the electrode outside the defined area, especially when the substrate upon which the electrode is placed is porous.
The present invention seeks to overcome or at least ameliorate the problems of the prior art by providing a method which is inexpensive, simple to apply and reliable.
SUMMARY OF THE INVENTION
According to one aspect the present invention consists in a method for defining an area of a layer on a porous substrate comprising compressing a volume of the substrate to produce a compressed region which defines, or which in combination with an edge of the substrate or of the layer defines, a boundary of the area and which substantially prevents the transport of material through or across its surface.
According to a second aspect the invention consists in an electrochemical sensing device comprising: substrate is compressed to an extent which forms a barrier to migration of electrolyte within the substrate, the compressed region defining, or in combination with an edge of the substrate or the electrode defining, a zone on the electrode of predetermined area.
According to a third aspect the porous substrate of the second aspect is a membrane that is permeable to a fluid containing a first species to be analysed but substantially impermeable to a second species contained in the fluid, the second species being of a kind which would interfere with electrochemical sensing of the first species.
Preferably, the layer, which may be attached to or in contact with the porous substrate or may be a coating applied to the substrate, is an electrode and the area being defined is an electrode area. When the layer is an electrode it is usually sputter deposited on the surface of the substrate so as to form a continuous film on the surface. However, other methods such as electroless plating, electroplating, evaporation, anodization or the like can be used to form the electrode. Usually the film thickness on the substrate is 10-200 nm, more preferably 60-120 nm.
Materials which would be suitable as an electrode include gold, silver, platinum, palladium, iridium, lead, and alloys of those metals, carbon, carbon mixed with a binding material, and silver partially covered with a porous layer of an insoluble silver salt such as silver chloride, silver bromide, silver iodide, silver ferricyanide and silver ferrocyanide. In electrochemical sensing devices according to the invention there will typically be two or more electrodes and these may be disposed on one side of the substrate or on opposite sides of the substrate.
In a preferred form the resulting substrate produced from the method of the invention will have at least two discrete regions--one region being compressed and the other region being uncompressed. This resulting substrate has been found to be particularly useful when used as an electrochemical sensi
REFERENCES:
patent: 4224125 (1980-09-01), Nakamura et al.
patent: 4233029 (1980-11-01), Columbus
patent: 4254083 (1981-03-01), Columbus
patent: 4259165 (1981-03-01), Miyake
patent: 4301412 (1981-11-01), Hill et al.
patent: 4301414 (1981-11-01), Hill et al.
patent: 4303887 (1981-12-01), Hill et al.
patent: 4307188 (1981-12-01), White
patent: 4374013 (1983-02-01), Enfors
patent: 4404066 (1983-09-01), Johnson
patent: 4431004 (1984-02-01), Bessman et al.
patent: 4517287 (1985-05-01), Scheibe et al.
patent: 4517291 (1985-05-01), Seago
patent: 4533440 (1985-08-01), Kim
patent: 4545382 (1985-10-01), Higgins et al.
patent: 4552840 (1985-11-01), Riffer
patent: 4629563 (1986-12-01), Wrasidlo
patent: 4654197 (1987-03-01), Lilja et al.
patent: 4664119 (1987-05-01), Bessman et al.
patent: 4711245 (1987-12-01), Higgins et al.
patent: 4774039 (1988-09-01), Wrasidlo
patent: 4790925 (1988-12-01), Miller et al.
patent: 4900424 (1990-02-01), Birth et al.
patent: 4919770 (1990-04-01), Preidel et al.
patent: 4963815 (1990-10-01), Hafeman
patent: 5059908 (1991-10-01), Mina
patent: 5064516 (1991-11-01), Rupich
patent: 5120420 (1992-06-01), Nankai et al.
patent: 5122244 (1992-06-01), Hoenes et al.
patent: 5126034 (1992-06-01), Carter et al.
patent: 5128015 (1992-07-01), Szuminsky et al.
patent: 5141868 (1992-08-01), Shanks et al.
patent: 5151166 (1992-09-01), Harral et al.
patent: 5192415 (1993-03-01), Yoshioka et al.
patent: 5229282 (1993-07-01), Yoshioka et al.
patent: 5272087 (1993-12-01), El Murr et al.
patent: 5320732 (1994-06-01), Nankai et al.
patent: 5382346 (1995-01-01), Uenoyama et al.
patent: 5384028 (1995-01-01), Ito
patent: 5385846 (1995-01-01), Kuhn et al.
patent: 5393399 (1995-02-01), Van Den Berg et al.
patent: 5413690 (1995-05-01), Kost et al.
patent: 5437999 (1995-08-01), Diebold et al.
patent: 5508171 (1996-04-01), Walling et al.
patent: 5509410 (1996-04-01), Hill et al.
patent: 5527446 (1996-06-01), Kosek et al.
patent: 5567302 (1996-10-01), Song et al.
patent: 5611908 (1997-03-01), Mattiessen et al.
patent: 5620579 (1997-04-01), Genshaw et al.
patent: 5628890 (1997-05-01), Carter et al.
patent: 5645709 (1997-07-01), Birch et al.
Derwent Abstract Accession No. 92 119462/15, Class S03, JP,A, 04-62463.(Tokyo Yogyo K.K.) Feb. 27, 1992.
Beck Thomas William
Hodges Alastair McIndoe
Johansen Oddvar
Noguerola Alex
Tung T.
USF Filtration and Separations Group
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