Abstract:
A test device and method for determining the presence or absence of one or more analytes in a fluid sample, the test device including a support (14) or member bearing a mark (46)thereon, and a matrix (18) or member containing a capture zone (40). In operation, an observation area (38) in the test device becomes transparent, thereby allowing the user to view a mark that is present on a support that is disposed beneath the observation area. Typically, the mark on the underlying support is configured as a minus (-) sign. In the absence of analyte in the sample, the test device presents a negative result as a minus (-) signal. In the presence of analyte in the sample, however, the mark operates in concert with a perpendicular test line on the observation area to present a positive result as a plus (+) signal that is visible to the user.
Abstract:
Laminated test devices comprising an indicator lamina (32) on one side of alight-transmissive substrate sheet (31) and a pigment lamina (35) on the other side.
Abstract:
Laminated test devices in which positive results are detected by the appearance of a symbol on the surface of the device due to a color change in an indicator in the device are improved by placing the indicator lamina on one side of a light-transmissive substrate sheet and a pigment lamina on the other side, the indicator lamina forming the icon and the pigment lamina forming the background, the pigment being the color of the indicator prior to the color change. This arrangement reduces false positive readings by obscuring the outlines of the symbol prior to the color change. False negative readings are reduced by further changes in the arrangement of the laminae.