Patent ID: 8389296

Claim:
An assay device for identifying the presence of a hapten, comprising a permeable material such that when an aqueous liquid is contacted with a first part of the permeable material it permeates to a second part of the permeable material, said permeable material having a first zone and a second zone disposed so that when the aqueous liquid is contacted with the first part of the permeable material it passes first through the first zone and then into the second zone as it permeates to the second part of the permeable material; said first zone comprising a signal generating means labeled with an antibody against a hapten to be identified; said first zone further comprising a binding material for said antibody against the hapten to be identified, wherein the binding material is a hapten or a close structural analogue thereof bound to a large molecule that prevents binding to a locating means when the binding material is bound to the antibody against the hapten; said second zone comprising said locating means for said antibody against the hapten to be identified such that the locating means binds to the antibody present on the signal generating means labelled with an antibody which has bound the hapten to be identified but does not bind to an antibody present on the signal generating means which has bound the binding material for said antibody against the hapten to be identified; the signal generating means being such that a signal is generated on binding to said locating means; wherein the locating means is not a specific binder for the antibody against the hapten to be identified.