Patent ID: 6986869

Claim:
A test strip, for detecting an analyte in a body fluid, comprising: a cover sheet having an elongated window cut through it; a lamellar membrane adjacent to the cover sheet, extending across the window and containing a reagent that reacts with the analyte to produce a color change; a relatively imcompressible center plate, adjacent to the membrane and having a central portion cut out of it to form an internal relief chamber, into which a portion of the membrane protrudes, the relief chamber being substantially aligned with the window; a porous sheet adjoining the center plate, in fluid communication with the membrane, and having a pillow portion that extends into the relief chamber; and a backing sheet adjoining the porous sheet and having a sample port cut through it; whereby fluid introduced into the sample port can flow through the porous sheet to the membrane, and analyte in the fluid can react with the reagent to produce a color change visible through the window.