Chemistry: analytical and immunological testing – Involving diffusion or migration of antigen or antibody
Reexamination Certificate
1999-06-25
2001-09-04
Chin, Christopher L. (Department: 1641)
Chemistry: analytical and immunological testing
Involving diffusion or migration of antigen or antibody
C422S051000, C422S051000, C422S051000, C422S051000, C422S067000, C435S011000, C435S014000, C435S174000, C435S180000, C435S287100, C435S287200, C435S287700, C435S287800, C435S287900, C435S805000, C435S810000, C435S970000, C436S066000, C436S071000, C436S164000, C436S169000, C436S170000, C436S518000, C436S531000, C436S805000, C436S810000, C436S815000, C436S827000
Reexamination Certificate
active
06284550
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates generally to analytical test strip devices, and more particularly to an improved diagnostic sanitary test strip device for determining the presence, absence, and/or amount of a predetermined analyte, and having a fluid sample volume control, structure to facilitate proper orientation of the strip in a corresponding meter, and an improved agent treatment solution for facilitating end-point testing.
2. Description of the Background Art
Analytical test strips for testing analytes in heterogeneous fluid samples are well known in the art and comprise various structures and materials. These test strips typically include single or multi-layered fibrous membrane devices which receive a heterogeneous fluid, such as whole blood, and undergo a color change in response to interaction with agents/reactants imbibed into the membrane. Prior to reaching the reactants, the fluid sample is filtered to facilitate accurate testing of the analyte. For instance, a blood sample being treated for glucose levels requires the removal of red blood cells before testing the plasma. Some test strips include additional layers that provide the requisite filtering. Other test strips attempt to filter and test a sample for a suspected analyte in a single membrane. Terminiello et al., U.S. Pat. No. 4,774,192, teaches such a dry chemistry reagent system which comprises a porous anisotropic (asymmetrical) membrane having a porosity gradient from one planar surface to the other for filtering a fluid sample and includes an indicator, flow control agent, and reagent cocktail imbibed therein for initiating the chemical reaction with the fluid sample. Anisotropic membranes, however, provide inadequate filtering and can have a tendency to produce unreliable results.
Test strip devices operate by allowing the applied heterogeneous sample to migrate to a reaction site in the membrane, where the analyte of interest in the sample reacts with the imbibed agents. The results of the reaction are usually visible through a color change in the membrane. The color change may be viewed with the naked eye and measured by a visual comparison with a color chart or reading it with a reflectance meter.
Certain problems have been noted in existing analytical test strips. Some of these problems include spillage of the sample over the edges of the strip, excessive absorption, and incomplete filtering, all of which can adversely affect test integrity. Other strips, such as those disclosed in U.S. Pat. No. 3,298,789 issued to Mast and U.S. Pat. No. 3,630,957 issued to Rey et al., require the sample to remain in contact with the reagant pad for specified time and that the blood sample be either washed or wiped off the pad. In addition, conventional strips have been known to be difficult to use in terms of the proper amount of heterogeneous fluid to place on the strip. It is also difficult to properly place and/or orient strips in a corresponding meter.
U.S. Pat. No. 5,296,192 (the “'192 Patent”), issued to the inventors herein, addresses some of these shortcomings noted in the background art. The '192 Patent teaches a multi-layered diagnostic test strip for receiving whole blood on which a test for a suspected analyte is performed. The multi-layered test strip device comprises two outside supports, sandwiching therebetween a spreading screen, a separating layer, and a membrane. The top support has a port for receiving the sample. The spreading screen evenly distributes the sample so that it uniformly passes into the separating layer. The separating layer removes a majority of the red blood cells from the blood sample, and the membrane removes the remaining cells. The membrane is also pretreated with reagents and conditioning agents needed for the reaction and insuring a readable, reliable color generation. The '192 Patent provides a strip that may be visually read with a color comparator or a reflectance meter. The instant invention provides an improved diagnostic test strip which is built in part on some of the teachings of the '192 Patent, and which has additional features for further enhancing the use and reliability of diagnostic testing. These improvements are submitted as solving the above-noted problems.
SUMMARY OF THE INVENTION
The present invention is directed to an improved, multi-layered sanitary test strip for receiving a heterogenous fluid that is tested for a suspected analyte. In the preferred embodiment, the heterogeneous fluid comprises a whole blood which is analyzed to determine the presence of analytes, such as glucose or cholesterol, to determine the presence, absence, and/or level of the analyte in the fluid. Accordingly, discussion herein is tailored to the receipt and testing of glucose analytes in a whole blood sample. As such, the suggested chemical reagents herein are specific to testing glucose in blood. It is important to note, however, that the instant invention may be used to determine the presence, absence, and/or amount of a substance in other heterogeneous fluids by modifying the chemical reagent solutions and/or concentrations employed. The diagnostic sanitary test strip may be used for other enzymes and immunoassays, such as cholesterol (HDL or LDL), ketones, theophylline, osteoporosis, H1AC, fructosamine and others. The present invention confirms the presence, absence, and/or amount of these analytes.
The multi-layered diagnostic sanitary test strip generally comprises two outside layers, between which are, in descending order, a spreading screen, a separating layer, a membrane, and a pretreatment reagent solution imbibed into the membrane. The multi-layered test strip taught herein improves on the teachings of the test strip disclosed in U.S. Pat. No. 5,296,192, the disclosure of which is incorporated herein by reference. The instant invention is an improvement in that it provides a chemistry reagent solution and concentration that facilitates end-point testing, volume control dams to prevent spills or overflow and reduce the amount of sample needed to perform a test, and a light absorption medium which visually and functionally prevents the test strip from being tested upside down. The improved diagnostic test strip also allows for the application of a heterogeneous fluid sample, e.g., blood, to the strip, both inside and outside the meter.
It is an object of the present invention to provide an improved multi-layered diagnostic sanitary test strip.
It is another object of the present invention to provide an improved multi-layered diagnostic sanitary test strip that prevents a heterogenous fluid sample from overflowing from the strip.
It is an additional object of the present invention to provide an improved multi-layered diagnostic sanitary test strip that is easier to use, requires a smaller amount of the heterogenous fluid sample and facilitates application of the sample on the strip when the strip is either outside or inserted in a meter.
It is a further object of the present invention to provide an improved multi-layered diagnostic sanitary test strip that facilitates proper placement and orientation of the strip in a corresponding meter.
It is yet another object of the present invention to provide an improved multi-layered diagnostic sanitary test strip that may be used in a meter that performs end-point testing.
It is yet an additional object of the present invention to provide an improved multi-layered diagnostic sanitary test strip that may be imbibed with a dry chemistry reagent solution that facilitates end-point testing.
In accordance with these and other objects which will become apparent hereinafter, the instant invention will now be described with particular reference to the accompanying drawings.
REFERENCES:
patent: 3992158 (1976-11-01), Przybylowic
patent: 4774192 (1988-09-01), Terminiello
patent: 4790979 (1988-12-01), Terminiello
patent: 4877580 (1989-10-01), Aronowitz
patent: 4935346 (1990-06-01), Phillips et al.
patent: 4987085 (1991-01-01), Allen et al.
patent: 4994238 (1991-02-01), Da
Bell Douglas E.
Carroll Patrick
Schneider Jon
Chin Christopher L.
Finnegan Henderson Farabow Garrett & Dunner L.L.P.
Home Diagnostics, Inc.
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