A device for use in a medical diagnostic apparatus includes an area for containing a sample of biological fluid as it undergoes a reaction that causes a detectable change in the sample's optical properties. The reaction area is sandwiched between a transparent front layer and a Fresnel reflector layer. The area is illuminated through the front layer, and the light is reflected from the reflector layer to a detector. The detector monitors the light incident on it and calculates, from the change during the course of the reaction, an analyte concentration or property of the fluid sample. The reaction area is optionally heated.
An article and a method for monitoring the concentration of an analyte, e. g., glucose, in blood. In one aspect, the invention involves an article comprising a multiple-layer element. In one embodiment, the article comprises: a multiple-layer element comprising: (a) a base layer (b) a cover layer, the cover layer having a first opening for venting the multiple-layer element and a second opening for receiving a biological sample; and (c) a core layer having a first major surface and a second major surface, the core layer disposed between the base layer and the cover layer, the core layer comprising a sample introduction chamber and a optical reading chamber, the first major surface of the core layer in face-to-face contact with the base layer, the second major surface of the core layer in face-to-face contact with the cover layer. The multiple-layer element of this invention allows the use of samples of blood or other biological fluids, such as interstitial fluid, to provide extremely sensitive assay results. The device has been shown to provide accurate and reproducible results with samples having volumes ranging from about 5 .mu.L to about 20 .mu.L. In another aspect, the invention involves a method for using the aforementioned article.
A test strip platform for a testing apparatus of the type using test strips, wherein the platform has a shroud defining a strip track for positioning an inserted strip over an optical aperture for making analytical determinations. The platform has a hood permanently mounted to the shroud for overlying the optical window and protecting the testing apparatus optics. The strip track has stabilizing members for holding the strip in testing position. The hood provides camming members for guiding the leading edge of an inserted strip into cooperative engagement with the stabilizing members for ensuring proper insertion of the strip.
A test strip platform for a testing apparatus of the type using test strips, wherein the platform has a shroud defining a strip track for positioning an inserted strip over an optical aperture for making analytical determinations. The platform has a hood permanently mounted to the shroud for overlying the optical window and protecting the testing apparatus optics. The strip track has stabilizing members for holding the strip in testing position. The hood provides camming members for guiding the leading edge of an inserted strip into cooperative engagement with the stabilizing members for ensuring proper insertion of the strip.
A method and apparatus for automatically selecting test types for an analytical meter system based on the insertion into the meter of a test element. The test element can be an analytical element, formed by a test strip with a fluid such as blood applied thereto; a control element, formed by a test strip with control fluid applied thereto; or a standard element, or a standard strip exhibiting known optical properties. By inserting the test element into the analytical meter system, optical properties are measured and the existence of relationships between the measurements are ascertained. Based on the existence or nonexistence of certain relationships, the proper test can be automatically selected by the meter without the need for user interaction. Advantageously, the results of the test can be classified and stored according to test type.
The present invention provides a method of measuring an analyte, such as glucose in a fluid sample, such as whole blood, by a reflectance reading device. The method includes making periodic intermediate calculations of analyte level and dynamically ascertaining when an analytical reaction has reached an end point. Once stable, the process stops making periodic calculations and reports the final, actual glucose concentration. According to an exemplary embodiment, the method is performed by a reflectance photometer using an analytical test strip containing reagents that react with an analyte of interest in the test fluid. The end point is determined by calculating an intermediate analyte level of the testing element at predetermined intervals and calculating a ratio value corresponding to the (n).sup.th measurement to an (n-5).sup.th measurement. When two consecutive ratio values are less than or equal to a predetermined value, the end point is deemed reached and the final analyte level ascertained.
