US4454094A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Test indicator for substances in liquids
Assignee: Alfa Laval AB
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Filing: 1982-03-01
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Granted: 1984-06-12
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Expires: 2002-03-01
Abstract
Abstract An indicator is disclosed, which is intended for detecting at least one test substance in a test medium, comprising a carrier and a reaction system consisting of at least a first reactant and a second reactant, applied separately on the carrier, said first reactant being intended to travel by diffusion to the second reactant through a parth in the carrier, soaked by the test medium, while reacting with the test substance. The indicator is characterized in that the first reactant is applied within at least one limited locality, while the second reactant is applied within at least one locality, on a varying distance from the locality of the first reactant.
Inventors
- 👤 Karl T. Bjorling
- 👤 Ann-Marie M. S. Gronberg
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 12:16
CPC Classifications
C; C12; C12Q; C12Q1/00; C12Q1/26; C12Q1/30; G; G01; G01N; G01N31/00; G01N31/22; G01N33/00; G01N33/48; G01N33/50; G01N33/52; G01N33/525; Y; Y10; Y10S; Y10S435/00; Y10S435/805
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
114 words
A device for indicating the presence of a defined substance in a liquid test medium comprising a substantially inert permeable substrate of substantially uniform thickness, a first reagent deposited in a first area of said substrate and being capable, upon contact with said test medium, of releasing a mobile substance capable of reacting with said defined substance, and a second reagent deposited in a second area of said substrate remote from said first area, and said second reagent being capable of changing color upon contact with said mobile substance, certain portions of said second area being more remote from the nearest portion of said first area than are other portions of said second area.
Claim 2
Independent Claim
114 words
A device for indicating the presence of a defined substance in a liquid test medium comprising a substantially inert permeable substrate of substantially uniform thickness, a first reagent deposited in a first area of said substrate and being capable, upon contact with said test medium, of releasing a mobile substance capable of reacting with said defined substance, and a second reagent deposited in a second area of said substrate remote from said first area, and said second reagent being capable of changing color upon contact with said mobile substance, certain portions of said second area being more remote from the nearest portion of said first area than are other portions of said second area.
Claim 3
Dependent Claim
19 words
The device claimed in claim 1 wherein one of said first and second areas is smaller than the other.
Claim 4
Dependent Claim
30 words
The device claimed in claim 1 wherein one of said areas comprises a series of concentric circular bands and the other is located at the center of said concentric bands.
Claim 5
Dependent Claim
32 words
The device claimed in claim 3 wherein one of said areas is located on one side of said substrate and the other area is located on an opposite side of said substrate.
Claim 6
Dependent Claim
17 words
The device claimed in claim 1 wherein the areas are bands on the surface of the substrate.
Claim 7
Dependent Claim
10 words
The device claimed in claim 5 wherein said bands diverge.
Claim 8
Dependent Claim
25 words
The device claimed in claim 5 wherein the bands are on opposite sides of the substrate and are perpendicularly positioned with respect to one another.
References Cited (Backward Citations)
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-06-12 | 1987-12-12 | 1988-06-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-06-12 | 1991-12-12 | 1992-06-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-06-12 | 1995-12-12 | 1996-06-12 | $7700.00 | Window Closed / Lapsed |