| abstract |
The present invention concerns a multilayer element for the analysis of liquids such as biochemical and biological liquids. Elements according to the invention include (1) a reagent layer including a composition that is interactive in the presence of a predetermined substance to be analyzed (analyte) to provide a diffusible, detectable species, and (2) a registration layer that is permeable to the detectable species and within which such species, e.g., a dye, can be detected. Also within the element, preferably between the reagent layer and the registration layer, there can be a radiation-blocking layer, such as an opaque reflecting layer, to enhance detection of the diffusible species within the registration layer. The element can also include a spreading layer, preferably separated from the registration layer by a reagent layer. In operation, a sample of liquid under analysis is applied to the reagent layer of the element or, if present, to a spreading layer. If the sample contains analyte that the element is intended to detect, chemical reaction or other interaction within the reagent layer provides a detectable species that diffuses, via any intervening layers such as a radiation-blocking layer, into the registration layer for detection there, such as by radiometric techniques like reflection spectrophotometry. |