Surface type microelectronic gas and vapor sensor
First Claim
1. A voltammetric microsensor structure, comprising:
- a substrate having an active area on a surface thereof;
a sensing electrode having a portion thereof on said active area;
a counter electrode having a portion thereof on said active area;
a reference electrode having a portion thereof on said active area;
said sensing electrode, said counter electrode and said reference electrode defining respectively therebetween a sensing-counter gap, a sensing-reference gap and a counter-reference gap;
a solid polymer electrolyte bridging said gaps;
a barrier covering said solid polymer electrolyte electrolyric medium, said barrier being permeable to an analyte gas; and
an aqueous reservoir internal of said substrate in flow contact with said electrolyte.
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Accused Products
Abstract
The present invention is concerned with electrode structures and microsensors having fast response times and high sensitivity and to methods using such structures and/or microsensors. This is accomplished in any one of several ways. In one, the sensing and counter electrodes are positioned close enough together on an active area so that ion migration therebetween is fast. The thickness of the electrolytic medium on the active area is restricted to be no more than about 10 microns so that diffusion therethrough between the electrodes is at least as fast as the ion migration. In another, the sensing electrode may have outwardly extending portions extending beyond the electrolytic medium and not being covered thereby. Or, conductive particles can be distributed in the electrolytic medium. Or the medium can be very thin. Or, the electrodes can be interdigited. Combinations of the above structural features are also set forth.
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Citations
88 Claims
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1. A voltammetric microsensor structure, comprising:
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a substrate having an active area on a surface thereof; a sensing electrode having a portion thereof on said active area; a counter electrode having a portion thereof on said active area; a reference electrode having a portion thereof on said active area; said sensing electrode, said counter electrode and said reference electrode defining respectively therebetween a sensing-counter gap, a sensing-reference gap and a counter-reference gap; a solid polymer electrolyte bridging said gaps; a barrier covering said solid polymer electrolyte electrolyric medium, said barrier being permeable to an analyte gas; and an aqueous reservoir internal of said substrate in flow contact with said electrolyte. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A method of voltammetrically determining the concentration of a gaseous species, comprising:
contacting a microsensor structure with the gaseous species in a gas phase and voltammetrically measuring the electrochemical effect of the species between sensing and counter electrode, the microsensor structure comprising a substrate having a sensing electrode, a counter electrode and a reference electrode, the electrodes defining respective sensing-counter, sensing-reference and counter-reference gaps between portions thereof mounted on an active area on the surface of the substrate, the gaps being bridged by a solid polymer electrolyte, a barrier covering said electrolyte, said barrier being permeable to an analyte gas and an aqueous reservoir internal of said substrate in flow contact with said electrolyte. - View Dependent Claims (10, 11)
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12. In a microsensor structure comprising a substrate having a surface having an active area, first and second adjacent electrodes having, respectively, sensing and counter portions on the active area;
- and an electrolytic medium covering the active area, the improvement comprising;
positioning the first and second electrodes sufficiently close together on said active area so that the time of migration of an ionic moiety from one to the other of the electrodes is no more than about 1 minute; restricting the thickness of the electrolytic medium to be no more than about 10 microns so that the time of diffusion of the gaseous species through the electrolytic medium to the first electrode is no more than about equal to the time of migration of the ionic moiety from one to the other of the electrodes; a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas; and an aqueous reservoir internal of said substrate in flow communication with said electrolytic medium.
- and an electrolytic medium covering the active area, the improvement comprising;
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13. In a microsensor structure comprising a substrate having a surface having an active area, first and second adjacent electrodes having, respectively, sensing and counter portions on the active area;
- and an electrolytic medium covering the active area, the improvement comprising;
positioning the first and second electrodes sufficiently close together on said active area so that the time of migration of an ionic moiety from one to the other of the electrodes is no more than about 1 minute; restricting the thickness of the electrolytic medium to be no more than about 10 microns so that the time of diffusion of the gaseous species through the electrolytic medium to the first electrode is no more than about equal to the time of migration of the ionic moiety from one to the other of the electrodes; a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas; a third electrode having a reference portion in contact with said electrolytic medium and free from contact with said first and second electrodes; and an aqueous reservoir internal of said substrate in flow contact with said electrolytic medium.
- and an electrolytic medium covering the active area, the improvement comprising;
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14. A microsensor structure for sensing an analyte in a gas phase, comprising:
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a substrate having a surface having an active area; a sensing electrode having a sensing portion on said active area, said sensing portion comprising a plurality of sensing fingers and having an outfacing surface facing away from said substrate; a counter electrode having a counter portion on said active area, said counter portion comprising a plurality of counter fingers, said counter fingers being positioned between and aligned generally along said sensing fingers to define sensing finger-counter finger gaps of no more than about 50 microns; a reference electrode having a reference portion on said active area and being free from contact with said sensing and counter electrodes; an electrolytic medium on said active area bridging said sensing finger-counter finger gaps and communicating said reference portion with said sensing portion, said electrolytic medium covering the active area by not covering the outfacing surface of said sensing electrode, the electrolytic medium, the sensing electrode and the gas phase forming a 3-phase sensing boundary; a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas; and an aqueous reservoir internal of said substrate in flow contact with said electrolytic medium.
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15. A microsensor structure for sensing an analyte in a gas phase, comprising:
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a substrate having a substrate surface having an active area; a sensing electrode on the substrate surface having a sensing portion upon the active area, the sensing portion having an outfacing surface facing away from the substrate; a solid electrolytic medium covering the active area but not covering the outfacing surface, the electrolytic medium, the first electrode and the gas phase forming a 3-phase sensing boundary; a counter electrode in contact with the electrolytic medium and free from contact with the sensing electrode; and a reference electrode in contact with the electrolytic medium and free from contact with the sensing and counter electrodes; a barrier covering said electrolytic medium, said barrier being permeable to an analyte gas; and an aqueous reservoir internal of said substrate in flow contact with said electrolytic medium. - View Dependent Claims (16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. An electrode structure, comprising:
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a first electrode having a sensing portion having an outfacing surface having uneven configuration including a plurality of outwardly extending portions; and an electrolytic medium covering said outfacing surface with said outwardly extending portions extending outwardly beyond said electrolytic medium and not being covered thereby. - View Dependent Claims (27, 28)
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29. A microsensor structure, comprising:
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a substrate having a substrate having an active area; a first electrode on with said substrate surface, said first electrode having a sensing portion on said active area, said sensing portion having an infacing surface facing said substrate surface and an outfacing surface facing away from said substrate surface, said outfacing surface having an uneven configuration including a plurality of outwardly extending portions; an electrolytic medium covering said outfacing surface with said outwardly extending portions extending outwardly beyond said electrolytic medium and not being covered thereby; and a second electrode on said electrolytic medium and free from contact with said first electrode. - View Dependent Claims (30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54)
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55. In a method of determining the concentration of a particular gaseous species which comprises contacting the species with a sensor having a substrate having a sensing electrode and a counter electrode on a surface thereof, the electrodes being covered by an electrolytic medium, and measuring the electrochemical effect of said species on said sensing electrode, the improvement comprising:
utilizing as said sensing electrode a first electrode having an outfacing surface having an uneven configuration including a plurality of outwardly extending portions which extend outwardly beyond said electrolytic medium and are not covered thereby. - View Dependent Claims (56, 57, 58, 59, 60, 61)
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62. A microsensor structure, comprising:
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a substrate having a substrate surface having an active area; a first electrode in contact with said substrate surface, said first electrode having a sensing portion on said active area, said sensing portion having infacing surface facing said substrate surface and an outfacing surface facing away from said substrate surface; a solid electrolytic medium covering said outfacing surface, said solid electrolytic medium having a plurality of conductive microparticles dispersed therein; and a second electrode in contact with said electrolytic medium and free from contact with said first electrode. - View Dependent Claims (63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83)
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84. In a method of determining the concentration of a particular gaseous species which comprises contacting the species with a sensor having a substrate having a sensing electrode and a counter electrode on a surface thereof, the electrode being covered by a solid electrolytic medium, and measuring the effect of said species on the sensing electrode, the improvement comprising:
including a plurality of conductive microparticles dispersed in said solid electrolytic medium. - View Dependent Claims (85, 86, 87, 88)
Specification