Patent ID: 7255832
Filing Date: 2007-08-14
Classification: G01N,Y10T

Abstract:
1. A test device for analyzing a liquid sample for the presence of a selected analyte, said test device comprising: a light-transmitting, liquid-impermeable substrate sheet coated on one side with an analyte indicator lamina and on an opposing side with a pigment lamina, said analyte indicator lamina reactive with said analyte in a reaction producing a color change in said analyte indicator lamina, and said pigment lamina being of the same composition as that of said indicator lamina, so that said pigment lamina is of a color visually indistinguishable from that of said analyte indicator lamina when said analyte indicator lamina is in unreacted condition, said pigment lamina fully covering a selected test region on said substrate, and means for restricting said color change in said analyte indicator lamina to a restricted area within, and smaller than, said test region, thereby leaving adjacent areas within said test region unchanged.