Cholestech Corporation

Gary E Hewett

Steven T Mielke

Ronald M Jones

Judith A Blunt

Eric G Barr

The invention relates to an immunoassay cassette useful for carrying out multistage immunoassays in an automated manner. In operation, the cassette assumes different operational positions in which solutions are transferred sequentially across an absorbent pathway containing assay reagents.

Automated immunoassay cassette

An assay device and method for determining the concentration of an analyte in a fluid sample. The device includes a porous-matrix reservoir which receives the sample to be assayed, and at least two reaction zones into which sample fluid is drawn from the reservoir. In an embodiment containing two reaction zones, a single-point standard curve which corrects for reduced-signal effects related to loss of reagent activity and linear inhibition effects, is used to determine analyte concentration. In an embodiment containing three reaction zones, a two-point standard curve which corrects for reduced-signal effects related loss of reagent activity and non-linear inhibition effects, is used to determine analyte concentration. Also disclosed is an apparatus which uses the device for automated or semi-automated analyte assay.

Self-corrected assay device

An assay device and method for determining the concentration of an analyte. Analyte introduced by liquid absorption into the matrix is used to generate H2O2, via an analyte-specific oxidase, and the H.sub.2 O.sub.2 is utilized by peroxidase in the presence of peroxidase to convert a substrate reagent to a colored reaction product. A trapping compound in the matrix competes with the substrate reagent, in the presence of the peroxidase enzyme, to produce a silent reaction product, thus proportionately reducing the amount of signal reaction product generated by a given amount of analyte. Detection of a wider range of analyte concentrations is therefore possible.

Assay device and method using a signal-modulating compound

Method and apparatus for use in determining the concentration of a selected analyte in a body-fluid sample. As the fluid sample is applied to a wettable, absorbent reaction pad, the extent of sample wetting of the pad is monitored by surface reflectance. This surface monitoring is used to control the volume of sample applied to the pad, to prevent overfilling the pad and to allow determination of the final sample volume applied. From the known sample volume and amount of analyte, the concentration of analyte in the sample can be accurately calculated in reaction components, trapping agents, matrix configuration, and analyte tested can be made.

Controlled-volume assay apparatus

An assay device for assaying multiple analytes in a drop-size blood sample. The device includes a sample dispenser designed to distribute a small-volume blood sample to multiple transfer sites, by capillary flow of the blood sample through sieving and distributing matrices which separate blood cells from serum as the sample fluid migrates toward the transfer sites. A test plate in the device carries multiple absorbent test pads, each containing reagent components for use in detection of a selected analyte. The test plate is mounted on the dispenser for movement toward and away from a transfer position at which the exposed surface regions of the pads are in contact with associated sample-transfer sites, for simultaneous transfer of sample fluid from such sites to the pads in the support.

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Milpitas, CA, United States of America

Gary E Hewett