EP0759555A2
Expired / Lapsed
EP
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Direct-reading reagent test strip
Assignee: LifeScan Inc
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Filing: 1996-08-02
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Granted: —
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Expires: 2016-08-02
Abstract
Abstract A multilayer reagent test strip measures the concentration of analyte in a liquid sample that is applied to it. The sample is guided to a number of assay areas arrayed along the strip, where the analyte can react with a reagent to cause a color change. Each assay area also includes an inhibitor for the color-change reaction. The inhibitor concentration increases in successive assay areas; thus, the number of areas that change color is a measure of the analyte concentration. The test strip is particularly adapted for measuring glucose in a whole blood sample. In a preferred embodiment, the sample is guided to the assay areas along a path formed by crushing selected areas of a membrane, and the assay areas are uncrushed areas of the membrane.
Inventors
- 👤 Joel Douglas
- 👤 Michael F. Tomasco
- 👤 Ernest Kiser
- 👤 Remedios Dato
- 👤 Edward G. Rice
- 👤 Deborah P. Tuohy
- 👤 Mark Maxson
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-10-23 11:27
CPC Classifications
C; C12; C12Q; C12Q1/00; C12Q1/54; G; G01; G01N; G01N33/00; G01N33/48; G01N33/50; G01N33/52; G01N33/525; G01N33/526; G01N33/66
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
291 words
An elongated multilayer reagent test strip for measuring the concentration of an analyte, such as glucose, in a sample of biological fluid, such as blood, that is applied to the strip, comprising: a) a bottom layer with a through hole for accepting the sample; b) a membrane layer, having a sample side facing the bottom layer and a testing side opposite to it, and containing a reagent that can react with the analyte to produce a color change, the reagent comprising i) a first component (such as glucose oxidase) that interacts with the analyte to form hydrogen peroxide; ii) a second component (such as a peroxidase and an indicator dye or dye couple that changes color when it is oxidized) that interacts with the hydrogen peroxide to undergo a color change; and iii) a third component (such as ascorbic acid) that inhibits the change in color of the second component; c) an intermediate layer between the bottom and membrane layers; and d) metering means for distributing sample along the strip, the metering means comprising i) a non-bibulous region in the membrane layer; and ii) a fluid transport channel formed in the intermediate layer for guiding sample over the surface of the non-bibulous region to a plurality of discrete bibulous assay areas arrayed along the length of the membrane layer; the inhibitor concentration increasing in a predetermined way with distance from a first end of the strip, so that a correspondingly increasing analyte concentration must be contained in a sample if it is to effect a color change, whereby one or more assay areas may change color when a sample is applied to the strip, and the color-changing area most distant from the first end indicates the analyte concentration in the sample.
Claim 2
Dependent Claim
23 words
The strip of claim 1 in which the bottom layer further comprises a plurality of through holes in alignment with the assay areas.
Claim 3
Dependent Claim
33 words
The strip of claim 1 or claim 2 in which the membrane layer comprises an anisotropic porous membrane having pores that are larger near the sample side and smaller near the testing side.
Claim 4
Dependent Claim
28 words
The strip of claim 3 in which the pore sizes are selected so that the red blood cells of a whole blood sample are trapped in the membrane.
Claim 5
Dependent Claim
23 words
The strip of any one of claims 1 to 4 in which the intermediate layer and/or the bottom layer comprises a thermoplastic sheet.
Claim 6
Dependent Claim
27 words
The strip of any one of claims 1 to 5 in which the bibulous and non-bibulous regions comprise uncrushed and crushed regions of the membrane layer, respectively.
Claim 7
Dependent Claim
36 words
The strip of any one of claims 1 to 6 further comprising a top layer that is contiguous with the top surface of the membrane layer and has through holes that align with the assay areas.
Claim 8
Dependent Claim
21 words
The strip of any one of claims 1 to 7 further comprising absorbent layers that contact each end of the membrane.
Claim 9
Dependent Claim
49 words
The strip of any one of claims 1 to 8 further comprising a timer element, which comprises an assay area that includes, in addition to the reagent, an amount of glucose that causes the area to change color a predetermined time after the sample is applied to the strip.
Claim 10
Independent Claim
119 words
A method for measuring the concentration of an analyte in a sample of biological fluid, comprising the steps of: (a) applying the sample to a reagent test strip that comprises: (i) a plurality of bibulous assay areas that each change color when contacted with fluid containing at least a predetermined amount of analyte, greater than the amount of analyte that causes a change in color of the assay areas that are closer to a first end of the strip and (ii) metering means for distributing the sample along a predetermined non-bibulous path to each of the assay areas and (b) observing the assay area that changes color and that is most distant from the first end of the strip.
References Cited (Backward Citations)
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