Assay device for liquid sample
View Patent ↗Disclosed is an assay device comprising liquid transport means adapted to take up a liquid sample and conduct the liquid to an analyte detection region operable to provide a test signal indicative of the presence and/or amount of an analyte in the liquid sample; the assay device further comprising a sample presence signal generation means, which is not generated by means of an immunoreaction. This sample presence signal generation means can comprise a colored portion, which is overlaid by a material (e.g. nitrocellulose) that is opaque, when dry, and translucent or transparent, when wet, to allow the colored portion to become visible to the user. In another embodiment the signal generation means comprises a color changing material which under-goes a change in its visible properties upon wetting (e.g. pH indication). A third embodiment uses a mobilizable detectable which, when wetted by the sample, is carried along resulting in a streaked line parallel with the flow direction.
1. An assay device for detecting an analyte in a liquid sample, the assay device comprising:
a casing, the casing comprising at least one window; a labeling region, the labeling region comprising a mobilizable labeled binding agent; and a nitrocellulose strip located within the casing, the nitrocellulose strip being substantially opaque in a dry state and being translucent when wet by the liquid sample, the nitrocellulose strip comprising:
(i) an analyte detection region comprising an immobilized binding agent which binds the analyte, the analyte detection region located downstream of the labeling region, wherein the analyte detection region is visible through the at least one window;
(ii) a control region located downstream of the analyte detection region; wherein the control region is visible through the at least one window; and the casing comprising a colored plastic protuberance on an inner surface which presses against the nitrocellulose strip on the side of the nitrocellulose strip that is not visible through the at least one window when the nitrocellulose strip is in a dry state; wherein in use, the liquid sample contacts and migrates along the nitrocellulose strip, and wherein the protuberance is visible to a user through the at least one window when the nitrocellulose strip is wet.
2. The assay device of claim 1 , wherein when analyte is present in the sample, analyte binds to the mobilizable labelled binding agent and the immobilized binding agent to form a test signal in the analyte detection region of the nitrocellulose strip.
3. The assay device of claim 1 wherein the color of the protuberance is selected so that it corresponds to the color of the analyte detection region.
4. The assay device of claim 2 , wherein the protuberance and the test signal form a symbol representative of a positive result in the presence of analyte.